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| author | Stephen Hemminger <stephen.hemminger@vyatta.com> | 2010-10-11 14:49:26 -0700 |
|---|---|---|
| committer | Stephen Hemminger <stephen.hemminger@vyatta.com> | 2010-10-11 15:19:40 -0700 |
| commit | 011c1d1c0766c65517ebd495465c99e86edb63ec (patch) | |
| tree | 30d8f6a13235af90897c3223554871ef52225462 /doc/bash.0 | |
| parent | 40cfaccf7b178b6239b5cd0013ef80b7ff8e503e (diff) | |
| download | vyatta-bash-011c1d1c0766c65517ebd495465c99e86edb63ec.tar.gz vyatta-bash-011c1d1c0766c65517ebd495465c99e86edb63ec.zip | |
Update to bash-4.1
Diffstat (limited to 'doc/bash.0')
| -rw-r--r-- | doc/bash.0 | 5358 |
1 files changed, 5358 insertions, 0 deletions
diff --git a/doc/bash.0 b/doc/bash.0 new file mode 100644 index 0000000..675cd2f --- /dev/null +++ b/doc/bash.0 @@ -0,0 +1,5358 @@ +BASH(1) BASH(1) + + + +NNAAMMEE + bash - GNU Bourne-Again SHell + +SSYYNNOOPPSSIISS + bbaasshh [options] [file] + +CCOOPPYYRRIIGGHHTT + Bash is Copyright (C) 1989-2009 by the Free Software Foundation, Inc. + +DDEESSCCRRIIPPTTIIOONN + BBaasshh is an sshh-compatible command language interpreter that executes + commands read from the standard input or from a file. BBaasshh also incor- + porates useful features from the _K_o_r_n and _C shells (kksshh and ccsshh). + + BBaasshh is intended to be a conformant implementation of the Shell and + Utilities portion of the IEEE POSIX specification (IEEE Standard + 1003.1). BBaasshh can be configured to be POSIX-conformant by default. + +OOPPTTIIOONNSS + In addition to the single-character shell options documented in the + description of the sseett builtin command, bbaasshh interprets the following + options when it is invoked: + + --cc _s_t_r_i_n_g If the --cc option is present, then commands are read from + _s_t_r_i_n_g. If there are arguments after the _s_t_r_i_n_g, they are + assigned to the positional parameters, starting with $$00. + --ii If the --ii option is present, the shell is _i_n_t_e_r_a_c_t_i_v_e. + --ll Make bbaasshh act as if it had been invoked as a login shell (see + IINNVVOOCCAATTIIOONN below). + --rr If the --rr option is present, the shell becomes _r_e_s_t_r_i_c_t_e_d + (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). + --ss If the --ss option is present, or if no arguments remain after + option processing, then commands are read from the standard + input. This option allows the positional parameters to be + set when invoking an interactive shell. + --DD A list of all double-quoted strings preceded by $$ is printed + on the standard output. These are the strings that are sub- + ject to language translation when the current locale is not CC + or PPOOSSIIXX. This implies the --nn option; no commands will be + executed. + [[--++]]OO [[_s_h_o_p_t___o_p_t_i_o_n]] + _s_h_o_p_t___o_p_t_i_o_n is one of the shell options accepted by the + sshhoopptt builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). If + _s_h_o_p_t___o_p_t_i_o_n is present, --OO sets the value of that option; ++OO + unsets it. If _s_h_o_p_t___o_p_t_i_o_n is not supplied, the names and + values of the shell options accepted by sshhoopptt are printed on + the standard output. If the invocation option is ++OO, the + output is displayed in a format that may be reused as input. + ---- A ---- signals the end of options and disables further option + processing. Any arguments after the ---- are treated as file- + names and arguments. An argument of -- is equivalent to ----. + + BBaasshh also interprets a number of multi-character options. These + options must appear on the command line before the single-character + options to be recognized. + + ----ddeebbuuggggeerr + Arrange for the debugger profile to be executed before the shell + starts. Turns on extended debugging mode (see the description + of the eexxttddeebbuugg option to the sshhoopptt builtin below) and shell + function tracing (see the description of the --oo ffuunnccttrraaccee option + to the sseett builtin below). + ----dduummpp--ppoo--ssttrriinnggss + Equivalent to --DD, but the output is in the GNU _g_e_t_t_e_x_t ppoo (por- + table object) file format. + ----dduummpp--ssttrriinnggss + Equivalent to --DD. + ----hheellpp Display a usage message on standard output and exit success- + fully. + ----iinniitt--ffiillee _f_i_l_e + ----rrccffiillee _f_i_l_e + Execute commands from _f_i_l_e instead of the standard personal ini- + tialization file _~_/_._b_a_s_h_r_c if the shell is interactive (see + IINNVVOOCCAATTIIOONN below). + + ----llooggiinn + Equivalent to --ll. + + ----nnooeeddiittiinngg + Do not use the GNU rreeaaddlliinnee library to read command lines when + the shell is interactive. + + ----nnoopprrooffiillee + Do not read either the system-wide startup file _/_e_t_c_/_p_r_o_f_i_l_e or + any of the personal initialization files _~_/_._b_a_s_h___p_r_o_f_i_l_e, + _~_/_._b_a_s_h___l_o_g_i_n, or _~_/_._p_r_o_f_i_l_e. By default, bbaasshh reads these + files when it is invoked as a login shell (see IINNVVOOCCAATTIIOONN + below). + + ----nnoorrcc Do not read and execute the personal initialization file + _~_/_._b_a_s_h_r_c if the shell is interactive. This option is on by + default if the shell is invoked as sshh. + + ----ppoossiixx + Change the behavior of bbaasshh where the default operation differs + from the POSIX standard to match the standard (_p_o_s_i_x _m_o_d_e). + + ----rreessttrriicctteedd + The shell becomes restricted (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). + + ----vveerrbboossee + Equivalent to --vv. + + ----vveerrssiioonn + Show version information for this instance of bbaasshh on the stan- + dard output and exit successfully. + +AARRGGUUMMEENNTTSS + If arguments remain after option processing, and neither the --cc nor the + --ss option has been supplied, the first argument is assumed to be the + name of a file containing shell commands. If bbaasshh is invoked in this + fashion, $$00 is set to the name of the file, and the positional parame- + ters are set to the remaining arguments. BBaasshh reads and executes com- + mands from this file, then exits. BBaasshh's exit status is the exit sta- + tus of the last command executed in the script. If no commands are + executed, the exit status is 0. An attempt is first made to open the + file in the current directory, and, if no file is found, then the shell + searches the directories in PPAATTHH for the script. + +IINNVVOOCCAATTIIOONN + A _l_o_g_i_n _s_h_e_l_l is one whose first character of argument zero is a --, or + one started with the ----llooggiinn option. + + An _i_n_t_e_r_a_c_t_i_v_e shell is one started without non-option arguments and + without the --cc option whose standard input and error are both connected + to terminals (as determined by _i_s_a_t_t_y(3)), or one started with the --ii + option. PPSS11 is set and $$-- includes ii if bbaasshh is interactive, allowing + a shell script or a startup file to test this state. + + The following paragraphs describe how bbaasshh executes its startup files. + If any of the files exist but cannot be read, bbaasshh reports an error. + Tildes are expanded in file names as described below under TTiillddee EExxppaann-- + ssiioonn in the EEXXPPAANNSSIIOONN section. + + When bbaasshh is invoked as an interactive login shell, or as a non-inter- + active shell with the ----llooggiinn option, it first reads and executes com- + mands from the file _/_e_t_c_/_p_r_o_f_i_l_e, if that file exists. After reading + that file, it looks for _~_/_._b_a_s_h___p_r_o_f_i_l_e, _~_/_._b_a_s_h___l_o_g_i_n, and _~_/_._p_r_o_f_i_l_e, + in that order, and reads and executes commands from the first one that + exists and is readable. The ----nnoopprrooffiillee option may be used when the + shell is started to inhibit this behavior. + + When a login shell exits, bbaasshh reads and executes commands from the + file _~_/_._b_a_s_h___l_o_g_o_u_t, if it exists. + + When an interactive shell that is not a login shell is started, bbaasshh + reads and executes commands from _~_/_._b_a_s_h_r_c, if that file exists. This + may be inhibited by using the ----nnoorrcc option. The ----rrccffiillee _f_i_l_e option + will force bbaasshh to read and execute commands from _f_i_l_e instead of + _~_/_._b_a_s_h_r_c. + + When bbaasshh is started non-interactively, to run a shell script, for + example, it looks for the variable BBAASSHH__EENNVV in the environment, expands + its value if it appears there, and uses the expanded value as the name + of a file to read and execute. BBaasshh behaves as if the following com- + mand were executed: + if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi + but the value of the PPAATTHH variable is not used to search for the file + name. + + If bbaasshh is invoked with the name sshh, it tries to mimic the startup + behavior of historical versions of sshh as closely as possible, while + conforming to the POSIX standard as well. When invoked as an interac- + tive login shell, or a non-interactive shell with the ----llooggiinn option, + it first attempts to read and execute commands from _/_e_t_c_/_p_r_o_f_i_l_e and + _~_/_._p_r_o_f_i_l_e, in that order. The ----nnoopprrooffiillee option may be used to + inhibit this behavior. When invoked as an interactive shell with the + name sshh, bbaasshh looks for the variable EENNVV, expands its value if it is + defined, and uses the expanded value as the name of a file to read and + execute. Since a shell invoked as sshh does not attempt to read and exe- + cute commands from any other startup files, the ----rrccffiillee option has no + effect. A non-interactive shell invoked with the name sshh does not + attempt to read any other startup files. When invoked as sshh, bbaasshh + enters _p_o_s_i_x mode after the startup files are read. + + When bbaasshh is started in _p_o_s_i_x mode, as with the ----ppoossiixx command line + option, it follows the POSIX standard for startup files. In this mode, + interactive shells expand the EENNVV variable and commands are read and + executed from the file whose name is the expanded value. No other + startup files are read. + + BBaasshh attempts to determine when it is being run with its standard input + connected to a a network connection, as if by the remote shell daemon, + usually _r_s_h_d, or the secure shell daemon _s_s_h_d. If bbaasshh determines it + is being run in this fashion, it reads and executes commands from + _~_/_._b_a_s_h_r_c, if that file exists and is readable. It will not do this if + invoked as sshh. The ----nnoorrcc option may be used to inhibit this behavior, + and the ----rrccffiillee option may be used to force another file to be read, + but _r_s_h_d does not generally invoke the shell with those options or + allow them to be specified. + + If the shell is started with the effective user (group) id not equal to + the real user (group) id, and the --pp option is not supplied, no startup + files are read, shell functions are not inherited from the environment, + the SSHHEELLLLOOPPTTSS, BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE variables, if they + appear in the environment, are ignored, and the effective user id is + set to the real user id. If the --pp option is supplied at invocation, + the startup behavior is the same, but the effective user id is not + reset. + +DDEEFFIINNIITTIIOONNSS + The following definitions are used throughout the rest of this docu- + ment. + bbllaannkk A space or tab. + wwoorrdd A sequence of characters considered as a single unit by the + shell. Also known as a ttookkeenn. + nnaammee A _w_o_r_d consisting only of alphanumeric characters and under- + scores, and beginning with an alphabetic character or an under- + score. Also referred to as an iiddeennttiiffiieerr. + mmeettaacchhaarraacctteerr + A character that, when unquoted, separates words. One of the + following: + || && ;; (( )) << >> ssppaaccee ttaabb + ccoonnttrrooll ooppeerraattoorr + A _t_o_k_e_n that performs a control function. It is one of the fol- + lowing symbols: + |||| && &&&& ;; ;;;; (( )) || ||&& <<nneewwlliinnee>> + +RREESSEERRVVEEDD WWOORRDDSS + _R_e_s_e_r_v_e_d _w_o_r_d_s are words that have a special meaning to the shell. The + following words are recognized as reserved when unquoted and either the + first word of a simple command (see SSHHEELLLL GGRRAAMMMMAARR below) or the third + word of a ccaassee or ffoorr command: + + !! ccaassee ddoo ddoonnee eelliiff eellssee eessaacc ffii ffoorr ffuunnccttiioonn iiff iinn sseelleecctt tthheenn uunnttiill + wwhhiillee {{ }} ttiimmee [[[[ ]]]] + +SSHHEELLLL GGRRAAMMMMAARR + SSiimmppllee CCoommmmaannddss + A _s_i_m_p_l_e _c_o_m_m_a_n_d is a sequence of optional variable assignments fol- + lowed by bbllaannkk-separated words and redirections, and terminated by a + _c_o_n_t_r_o_l _o_p_e_r_a_t_o_r. The first word specifies the command to be executed, + and is passed as argument zero. The remaining words are passed as + arguments to the invoked command. + + The return value of a _s_i_m_p_l_e _c_o_m_m_a_n_d is its exit status, or 128+_n if + the command is terminated by signal _n. + + PPiippeelliinneess + A _p_i_p_e_l_i_n_e is a sequence of one or more commands separated by one of + the control operators || or ||&&. The format for a pipeline is: + + [ttiimmee [--pp]] [ ! ] _c_o_m_m_a_n_d [ [|||||&&] _c_o_m_m_a_n_d_2 ... ] + + The standard output of _c_o_m_m_a_n_d is connected via a pipe to the standard + input of _c_o_m_m_a_n_d_2. This connection is performed before any redirec- + tions specified by the command (see RREEDDIIRREECCTTIIOONN below). If ||&& is used, + the standard error of _c_o_m_m_a_n_d is connected to _c_o_m_m_a_n_d_2's standard input + through the pipe; it is shorthand for 22>>&&11 ||. This implicit redirect- + ion of the standard error is performed after any redirections specified + by the command. + + The return status of a pipeline is the exit status of the last command, + unless the ppiippeeffaaiill option is enabled. If ppiippeeffaaiill is enabled, the + pipeline's return status is the value of the last (rightmost) command + to exit with a non-zero status, or zero if all commands exit success- + fully. If the reserved word !! precedes a pipeline, the exit status of + that pipeline is the logical negation of the exit status as described + above. The shell waits for all commands in the pipeline to terminate + before returning a value. + + If the ttiimmee reserved word precedes a pipeline, the elapsed as well as + user and system time consumed by its execution are reported when the + pipeline terminates. The --pp option changes the output format to that + specified by POSIX. The TTIIMMEEFFOORRMMAATT variable may be set to a format + string that specifies how the timing information should be displayed; + see the description of TTIIMMEEFFOORRMMAATT under SShheellll VVaarriiaabblleess below. + + Each command in a pipeline is executed as a separate process (i.e., in + a subshell). + + LLiissttss + A _l_i_s_t is a sequence of one or more pipelines separated by one of the + operators ;;, &&, &&&&, or ||||, and optionally terminated by one of ;;, &&, or + <<nneewwlliinnee>>. + + Of these list operators, &&&& and |||| have equal precedence, followed by ;; + and &&, which have equal precedence. + + A sequence of one or more newlines may appear in a _l_i_s_t instead of a + semicolon to delimit commands. + + If a command is terminated by the control operator &&, the shell exe- + cutes the command in the _b_a_c_k_g_r_o_u_n_d in a subshell. The shell does not + wait for the command to finish, and the return status is 0. Commands + separated by a ;; are executed sequentially; the shell waits for each + command to terminate in turn. The return status is the exit status of + the last command executed. + + AND and OR lists are sequences of one of more pipelines separated by + the &&&& and |||| control operators, respectively. AND and OR lists are + executed with left associativity. An AND list has the form + + _c_o_m_m_a_n_d_1 &&&& _c_o_m_m_a_n_d_2 + + _c_o_m_m_a_n_d_2 is executed if, and only if, _c_o_m_m_a_n_d_1 returns an exit status + of zero. + + An OR list has the form + + _c_o_m_m_a_n_d_1 |||| _c_o_m_m_a_n_d_2 + + + _c_o_m_m_a_n_d_2 is executed if and only if _c_o_m_m_a_n_d_1 returns a non-zero exit + status. The return status of AND and OR lists is the exit status of + the last command executed in the list. + + CCoommppoouunndd CCoommmmaannddss + A _c_o_m_p_o_u_n_d _c_o_m_m_a_n_d is one of the following: + + (_l_i_s_t) _l_i_s_t is executed in a subshell environment (see CCOOMMMMAANNDD EEXXEECCUU-- + TTIIOONN EENNVVIIRROONNMMEENNTT below). Variable assignments and builtin com- + mands that affect the shell's environment do not remain in + effect after the command completes. The return status is the + exit status of _l_i_s_t. + + { _l_i_s_t; } + _l_i_s_t is simply executed in the current shell environment. _l_i_s_t + must be terminated with a newline or semicolon. This is known + as a _g_r_o_u_p _c_o_m_m_a_n_d. The return status is the exit status of + _l_i_s_t. Note that unlike the metacharacters (( and )), {{ and }} are + _r_e_s_e_r_v_e_d _w_o_r_d_s and must occur where a reserved word is permitted + to be recognized. Since they do not cause a word break, they + must be separated from _l_i_s_t by whitespace or another shell + metacharacter. + + ((_e_x_p_r_e_s_s_i_o_n)) + The _e_x_p_r_e_s_s_i_o_n is evaluated according to the rules described + below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. If the value of the expres- + sion is non-zero, the return status is 0; otherwise the return + status is 1. This is exactly equivalent to lleett ""_e_x_p_r_e_s_s_i_o_n"". + + [[[[ _e_x_p_r_e_s_s_i_o_n ]]]] + Return a status of 0 or 1 depending on the evaluation of the + conditional expression _e_x_p_r_e_s_s_i_o_n. Expressions are composed of + the primaries described below under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. + Word splitting and pathname expansion are not performed on the + words between the [[[[ and ]]]]; tilde expansion, parameter and + variable expansion, arithmetic expansion, command substitution, + process substitution, and quote removal are performed. Condi- + tional operators such as --ff must be unquoted to be recognized as + primaries. + + When used with [[[[, The << and >> operators sort lexicographically + using the current locale. + + When the ==== and !!== operators are used, the string to the right + of the operator is considered a pattern and matched according to + the rules described below under PPaatttteerrnn MMaattcchhiinngg. If the shell + option nnooccaasseemmaattcchh is enabled, the match is performed without + regard to the case of alphabetic characters. The return value + is 0 if the string matches (====) or does not match (!!==) the pat- + tern, and 1 otherwise. Any part of the pattern may be quoted to + force it to be matched as a string. + + An additional binary operator, ==~~, is available, with the same + precedence as ==== and !!==. When it is used, the string to the + right of the operator is considered an extended regular expres- + sion and matched accordingly (as in _r_e_g_e_x(3)). The return value + is 0 if the string matches the pattern, and 1 otherwise. If the + regular expression is syntactically incorrect, the conditional + expression's return value is 2. If the shell option nnooccaasseemmaattcchh + is enabled, the match is performed without regard to the case of + alphabetic characters. Any part of the pattern may be quoted to + force it to be matched as a string. Substrings matched by + parenthesized subexpressions within the regular expression are + saved in the array variable BBAASSHH__RREEMMAATTCCHH. The element of + BBAASSHH__RREEMMAATTCCHH with index 0 is the portion of the string matching + the entire regular expression. The element of BBAASSHH__RREEMMAATTCCHH with + index _n is the portion of the string matching the _nth parenthe- + sized subexpression. + + Expressions may be combined using the following operators, + listed in decreasing order of precedence: + + (( _e_x_p_r_e_s_s_i_o_n )) + Returns the value of _e_x_p_r_e_s_s_i_o_n. This may be used to + override the normal precedence of operators. + !! _e_x_p_r_e_s_s_i_o_n + True if _e_x_p_r_e_s_s_i_o_n is false. + _e_x_p_r_e_s_s_i_o_n_1 &&&& _e_x_p_r_e_s_s_i_o_n_2 + True if both _e_x_p_r_e_s_s_i_o_n_1 and _e_x_p_r_e_s_s_i_o_n_2 are true. + _e_x_p_r_e_s_s_i_o_n_1 |||| _e_x_p_r_e_s_s_i_o_n_2 + True if either _e_x_p_r_e_s_s_i_o_n_1 or _e_x_p_r_e_s_s_i_o_n_2 is true. + + The &&&& and |||| operators do not evaluate _e_x_p_r_e_s_s_i_o_n_2 if the value + of _e_x_p_r_e_s_s_i_o_n_1 is sufficient to determine the return value of + the entire conditional expression. + + ffoorr _n_a_m_e [ [ iinn [ _w_o_r_d _._._. ] ] ; ] ddoo _l_i_s_t ; ddoonnee + The list of words following iinn is expanded, generating a list of + items. The variable _n_a_m_e is set to each element of this list in + turn, and _l_i_s_t is executed each time. If the iinn _w_o_r_d is omit- + ted, the ffoorr command executes _l_i_s_t once for each positional + parameter that is set (see PPAARRAAMMEETTEERRSS below). The return status + is the exit status of the last command that executes. If the + expansion of the items following iinn results in an empty list, no + commands are executed, and the return status is 0. + + ffoorr (( _e_x_p_r_1 ; _e_x_p_r_2 ; _e_x_p_r_3 )) ; ddoo _l_i_s_t ; ddoonnee + First, the arithmetic expression _e_x_p_r_1 is evaluated according to + the rules described below under AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. The + arithmetic expression _e_x_p_r_2 is then evaluated repeatedly until + it evaluates to zero. Each time _e_x_p_r_2 evaluates to a non-zero + value, _l_i_s_t is executed and the arithmetic expression _e_x_p_r_3 is + evaluated. If any expression is omitted, it behaves as if it + evaluates to 1. The return value is the exit status of the last + command in _l_i_s_t that is executed, or false if any of the expres- + sions is invalid. + + sseelleecctt _n_a_m_e [ iinn _w_o_r_d ] ; ddoo _l_i_s_t ; ddoonnee + The list of words following iinn is expanded, generating a list of + items. The set of expanded words is printed on the standard + error, each preceded by a number. If the iinn _w_o_r_d is omitted, + the positional parameters are printed (see PPAARRAAMMEETTEERRSS below). + The PPSS33 prompt is then displayed and a line read from the stan- + dard input. If the line consists of a number corresponding to + one of the displayed words, then the value of _n_a_m_e is set to + that word. If the line is empty, the words and prompt are dis- + played again. If EOF is read, the command completes. Any other + value read causes _n_a_m_e to be set to null. The line read is + saved in the variable RREEPPLLYY. The _l_i_s_t is executed after each + selection until a bbrreeaakk command is executed. The exit status of + sseelleecctt is the exit status of the last command executed in _l_i_s_t, + or zero if no commands were executed. + + ccaassee _w_o_r_d iinn [ [(] _p_a_t_t_e_r_n [ || _p_a_t_t_e_r_n ] ... ) _l_i_s_t ;; ] ... eessaacc + A ccaassee command first expands _w_o_r_d, and tries to match it against + each _p_a_t_t_e_r_n in turn, using the same matching rules as for path- + name expansion (see PPaatthhnnaammee EExxppaannssiioonn below). The _w_o_r_d is + expanded using tilde expansion, parameter and variable expan- + sion, arithmetic substitution, command substitution, process + substitution and quote removal. Each _p_a_t_t_e_r_n examined is + expanded using tilde expansion, parameter and variable expan- + sion, arithmetic substitution, command substitution, and process + substitution. If the shell option nnooccaasseemmaattcchh is enabled, the + match is performed without regard to the case of alphabetic + characters. When a match is found, the corresponding _l_i_s_t is + executed. If the ;;;; operator is used, no subsequent matches are + attempted after the first pattern match. Using ;;&& in place of + ;;;; causes execution to continue with the _l_i_s_t associated with + the next set of patterns. Using ;;;;&& in place of ;;;; causes the + shell to test the next pattern list in the statement, if any, + and execute any associated _l_i_s_t on a successful match. The exit + status is zero if no pattern matches. Otherwise, it is the exit + status of the last command executed in _l_i_s_t. + + iiff _l_i_s_t; tthheenn _l_i_s_t_; [ eelliiff _l_i_s_t; tthheenn _l_i_s_t; ] ... [ eellssee _l_i_s_t; ] ffii + The iiff _l_i_s_t is executed. If its exit status is zero, the tthheenn + _l_i_s_t is executed. Otherwise, each eelliiff _l_i_s_t is executed in + turn, and if its exit status is zero, the corresponding tthheenn + _l_i_s_t is executed and the command completes. Otherwise, the eellssee + _l_i_s_t is executed, if present. The exit status is the exit sta- + tus of the last command executed, or zero if no condition tested + true. + + wwhhiillee _l_i_s_t; ddoo _l_i_s_t; ddoonnee + uunnttiill _l_i_s_t; ddoo _l_i_s_t; ddoonnee + The wwhhiillee command continuously executes the ddoo _l_i_s_t as long as + the last command in _l_i_s_t returns an exit status of zero. The + uunnttiill command is identical to the wwhhiillee command, except that the + test is negated; the ddoo _l_i_s_t is executed as long as the last + command in _l_i_s_t returns a non-zero exit status. The exit status + of the wwhhiillee and uunnttiill commands is the exit status of the last + ddoo _l_i_s_t command executed, or zero if none was executed. + + CCoopprroocceesssseess + A _c_o_p_r_o_c_e_s_s is a shell command preceded by the ccoopprroocc reserved word. A + coprocess is executed asynchronously in a subshell, as if the command + had been terminated with the && control operator, with a two-way pipe + established between the executing shell and the coprocess. + + The format for a coprocess is: + + ccoopprroocc [_N_A_M_E] _c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n_s] + + This creates a coprocess named _N_A_M_E. If _N_A_M_E is not supplied, the + default name is _C_O_P_R_O_C. _N_A_M_E must not be supplied if _c_o_m_m_a_n_d is a _s_i_m_- + _p_l_e _c_o_m_m_a_n_d (see above); otherwise, it is interpreted as the first word + of the simple command. When the coproc is executed, the shell creates + an array variable (see AArrrraayyss below) named _N_A_M_E in the context of the + executing shell. The standard output of _c_o_m_m_a_n_d is connected via a + pipe to a file descriptor in the executing shell, and that file + descriptor is assigned to _N_A_M_E[0]. The standard input of _c_o_m_m_a_n_d is + connected via a pipe to a file descriptor in the executing shell, and + that file descriptor is assigned to _N_A_M_E[1]. This pipe is established + before any redirections specified by the command (see RREEDDIIRREECCTTIIOONN + below). The file descriptors can be utilized as arguments to shell + commands and redirections using standard word expansions. The process + id of the shell spawned to execute the coprocess is available as the + value of the variable _N_A_M_E_PID. The wwaaiitt builtin command may be used + to wait for the coprocess to terminate. + + The return status of a coprocess is the exit status of _c_o_m_m_a_n_d. + + SShheellll FFuunnccttiioonn DDeeffiinniittiioonnss + A shell function is an object that is called like a simple command and + executes a compound command with a new set of positional parameters. + Shell functions are declared as follows: + + [ ffuunnccttiioonn ] _n_a_m_e () _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d [_r_e_d_i_r_e_c_t_i_o_n] + This defines a function named _n_a_m_e. The reserved word ffuunnccttiioonn + is optional. If the ffuunnccttiioonn reserved word is supplied, the + parentheses are optional. The _b_o_d_y of the function is the com- + pound command _c_o_m_p_o_u_n_d_-_c_o_m_m_a_n_d (see CCoommppoouunndd CCoommmmaannddss above). + That command is usually a _l_i_s_t of commands between { and }, but + may be any command listed under CCoommppoouunndd CCoommmmaannddss above. _c_o_m_- + _p_o_u_n_d_-_c_o_m_m_a_n_d is executed whenever _n_a_m_e is specified as the name + of a simple command. Any redirections (see RREEDDIIRREECCTTIIOONN below) + specified when a function is defined are performed when the + function is executed. The exit status of a function definition + is zero unless a syntax error occurs or a readonly function with + the same name already exists. When executed, the exit status of + a function is the exit status of the last command executed in + the body. (See FFUUNNCCTTIIOONNSS below.) + +CCOOMMMMEENNTTSS + In a non-interactive shell, or an interactive shell in which the iinntteerr-- + aaccttiivvee__ccoommmmeennttss option to the sshhoopptt builtin is enabled (see SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below), a word beginning with ## causes that word and + all remaining characters on that line to be ignored. An interactive + shell without the iinntteerraaccttiivvee__ccoommmmeennttss option enabled does not allow + comments. The iinntteerraaccttiivvee__ccoommmmeennttss option is on by default in interac- + tive shells. + +QQUUOOTTIINNGG + _Q_u_o_t_i_n_g is used to remove the special meaning of certain characters or + words to the shell. Quoting can be used to disable special treatment + for special characters, to prevent reserved words from being recognized + as such, and to prevent parameter expansion. + + Each of the _m_e_t_a_c_h_a_r_a_c_t_e_r_s listed above under DDEEFFIINNIITTIIOONNSS has special + meaning to the shell and must be quoted if it is to represent itself. + + When the command history expansion facilities are being used (see HHIISS-- + TTOORRYY EEXXPPAANNSSIIOONN below), the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, usually !!, must + be quoted to prevent history expansion. + + There are three quoting mechanisms: the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r, single + quotes, and double quotes. + + A non-quoted backslash (\\) is the _e_s_c_a_p_e _c_h_a_r_a_c_t_e_r. It preserves the + literal value of the next character that follows, with the exception of + <newline>. If a \\<newline> pair appears, and the backslash is not + itself quoted, the \\<newline> is treated as a line continuation (that + is, it is removed from the input stream and effectively ignored). + + Enclosing characters in single quotes preserves the literal value of + each character within the quotes. A single quote may not occur between + single quotes, even when preceded by a backslash. + + Enclosing characters in double quotes preserves the literal value of + all characters within the quotes, with the exception of $$, ``, \\, and, + when history expansion is enabled, !!. The characters $$ and `` retain + their special meaning within double quotes. The backslash retains its + special meaning only when followed by one of the following characters: + $$, ``, "", \\, or <<nneewwlliinnee>>. A double quote may be quoted within double + quotes by preceding it with a backslash. If enabled, history expansion + will be performed unless an !! appearing in double quotes is escaped + using a backslash. The backslash preceding the !! is not removed. + + The special parameters ** and @@ have special meaning when in double + quotes (see PPAARRAAMMEETTEERRSS below). + + Words of the form $$'_s_t_r_i_n_g' are treated specially. The word expands to + _s_t_r_i_n_g, with backslash-escaped characters replaced as specified by the + ANSI C standard. Backslash escape sequences, if present, are decoded + as follows: + \\aa alert (bell) + \\bb backspace + \\ee + \\EE an escape character + \\ff form feed + \\nn new line + \\rr carriage return + \\tt horizontal tab + \\vv vertical tab + \\\\ backslash + \\'' single quote + \\"" double quote + \\_n_n_n the eight-bit character whose value is the octal value + _n_n_n (one to three digits) + \\xx_H_H the eight-bit character whose value is the hexadecimal + value _H_H (one or two hex digits) + \\cc_x a control-_x character + + The expanded result is single-quoted, as if the dollar sign had not + been present. + + A double-quoted string preceded by a dollar sign ($$"_s_t_r_i_n_g") will cause + the string to be translated according to the current locale. If the + current locale is CC or PPOOSSIIXX, the dollar sign is ignored. If the + string is translated and replaced, the replacement is double-quoted. + +PPAARRAAMMEETTEERRSS + A _p_a_r_a_m_e_t_e_r is an entity that stores values. It can be a _n_a_m_e, a num- + ber, or one of the special characters listed below under SSppeecciiaall PPaarraamm-- + eetteerrss. A _v_a_r_i_a_b_l_e is a parameter denoted by a _n_a_m_e. A variable has a + _v_a_l_u_e and zero or more _a_t_t_r_i_b_u_t_e_s. Attributes are assigned using the + ddeeccllaarree builtin command (see ddeeccllaarree below in SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS). + + A parameter is set if it has been assigned a value. The null string is + a valid value. Once a variable is set, it may be unset only by using + the uunnsseett builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + A _v_a_r_i_a_b_l_e may be assigned to by a statement of the form + + _n_a_m_e=[_v_a_l_u_e] + + If _v_a_l_u_e is not given, the variable is assigned the null string. All + _v_a_l_u_e_s undergo tilde expansion, parameter and variable expansion, com- + mand substitution, arithmetic expansion, and quote removal (see EEXXPPAANN-- + SSIIOONN below). If the variable has its iinntteeggeerr attribute set, then _v_a_l_u_e + is evaluated as an arithmetic expression even if the $((...)) expansion + is not used (see AArriitthhmmeettiicc EExxppaannssiioonn below). Word splitting is not + performed, with the exception of ""$$@@"" as explained below under SSppeecciiaall + PPaarraammeetteerrss. Pathname expansion is not performed. Assignment state- + ments may also appear as arguments to the aalliiaass, ddeeccllaarree, ttyyppeesseett, + eexxppoorrtt, rreeaaddoonnllyy, and llooccaall builtin commands. + + In the context where an assignment statement is assigning a value to a + shell variable or array index, the += operator can be used to append to + or add to the variable's previous value. When += is applied to a vari- + able for which the integer attribute has been set, _v_a_l_u_e is evaluated + as an arithmetic expression and added to the variable's current value, + which is also evaluated. When += is applied to an array variable using + compound assignment (see AArrrraayyss below), the variable's value is not + unset (as it is when using =), and new values are appended to the array + beginning at one greater than the array's maximum index (for indexed + arrays) or added as additional key-value pairs in an associative array. + When applied to a string-valued variable, _v_a_l_u_e is expanded and + appended to the variable's value. + + PPoossiittiioonnaall PPaarraammeetteerrss + A _p_o_s_i_t_i_o_n_a_l _p_a_r_a_m_e_t_e_r is a parameter denoted by one or more digits, + other than the single digit 0. Positional parameters are assigned from + the shell's arguments when it is invoked, and may be reassigned using + the sseett builtin command. Positional parameters may not be assigned to + with assignment statements. The positional parameters are temporarily + replaced when a shell function is executed (see FFUUNNCCTTIIOONNSS below). + + When a positional parameter consisting of more than a single digit is + expanded, it must be enclosed in braces (see EEXXPPAANNSSIIOONN below). + + SSppeecciiaall PPaarraammeetteerrss + The shell treats several parameters specially. These parameters may + only be referenced; assignment to them is not allowed. + ** Expands to the positional parameters, starting from one. When + the expansion occurs within double quotes, it expands to a sin- + gle word with the value of each parameter separated by the first + character of the IIFFSS special variable. That is, "$$**" is equiva- + lent to "$$11_c$$22_c......", where _c is the first character of the value + of the IIFFSS variable. If IIFFSS is unset, the parameters are sepa- + rated by spaces. If IIFFSS is null, the parameters are joined + without intervening separators. + @@ Expands to the positional parameters, starting from one. When + the expansion occurs within double quotes, each parameter + expands to a separate word. That is, "$$@@" is equivalent to "$$11" + "$$22" ... If the double-quoted expansion occurs within a word, + the expansion of the first parameter is joined with the begin- + ning part of the original word, and the expansion of the last + parameter is joined with the last part of the original word. + When there are no positional parameters, "$$@@" and $$@@ expand to + nothing (i.e., they are removed). + ## Expands to the number of positional parameters in decimal. + ?? Expands to the exit status of the most recently executed fore- + ground pipeline. + -- Expands to the current option flags as specified upon invoca- + tion, by the sseett builtin command, or those set by the shell + itself (such as the --ii option). + $$ Expands to the process ID of the shell. In a () subshell, it + expands to the process ID of the current shell, not the sub- + shell. + !! Expands to the process ID of the most recently executed back- + ground (asynchronous) command. + 00 Expands to the name of the shell or shell script. This is set + at shell initialization. If bbaasshh is invoked with a file of com- + mands, $$00 is set to the name of that file. If bbaasshh is started + with the --cc option, then $$00 is set to the first argument after + the string to be executed, if one is present. Otherwise, it is + set to the file name used to invoke bbaasshh, as given by argument + zero. + __ At shell startup, set to the absolute pathname used to invoke + the shell or shell script being executed as passed in the envi- + ronment or argument list. Subsequently, expands to the last + argument to the previous command, after expansion. Also set to + the full pathname used to invoke each command executed and + placed in the environment exported to that command. When check- + ing mail, this parameter holds the name of the mail file cur- + rently being checked. + + SShheellll VVaarriiaabblleess + The following variables are set by the shell: + + BBAASSHH Expands to the full file name used to invoke this instance of + bbaasshh. + BBAASSHHOOPPTTSS + A colon-separated list of enabled shell options. Each word in + the list is a valid argument for the --ss option to the sshhoopptt + builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The options + appearing in BBAASSHHOOPPTTSS are those reported as _o_n by sshhoopptt. If + this variable is in the environment when bbaasshh starts up, each + shell option in the list will be enabled before reading any + startup files. This variable is read-only. + BBAASSHHPPIIDD + Expands to the process id of the current bbaasshh process. This + differs from $$$$ under certain circumstances, such as subshells + that do not require bbaasshh to be re-initialized. + BBAASSHH__AALLIIAASSEESS + An associative array variable whose members correspond to the + internal list of aliases as maintained by the aalliiaass builtin Ele- + ments added to this array appear in the alias list; unsetting + array elements cause aliases to be removed from the alias list. + BBAASSHH__AARRGGCC + An array variable whose values are the number of parameters in + each frame of the current bbaasshh execution call stack. The number + of parameters to the current subroutine (shell function or + script executed with .. or ssoouurrccee) is at the top of the stack. + When a subroutine is executed, the number of parameters passed + is pushed onto BBAASSHH__AARRGGCC. The shell sets BBAASSHH__AARRGGCC only when in + extended debugging mode (see the description of the eexxttddeebbuugg + option to the sshhoopptt builtin below) + BBAASSHH__AARRGGVV + An array variable containing all of the parameters in the cur- + rent bbaasshh execution call stack. The final parameter of the last + subroutine call is at the top of the stack; the first parameter + of the initial call is at the bottom. When a subroutine is exe- + cuted, the parameters supplied are pushed onto BBAASSHH__AARRGGVV. The + shell sets BBAASSHH__AARRGGVV only when in extended debugging mode (see + the description of the eexxttddeebbuugg option to the sshhoopptt builtin + below) + BBAASSHH__CCMMDDSS + An associative array variable whose members correspond to the + internal hash table of commands as maintained by the hhaasshh + builtin. Elements added to this array appear in the hash table; + unsetting array elements cause commands to be removed from the + hash table. + BBAASSHH__CCOOMMMMAANNDD + The command currently being executed or about to be executed, + unless the shell is executing a command as the result of a trap, + in which case it is the command executing at the time of the + trap. + BBAASSHH__EEXXEECCUUTTIIOONN__SSTTRRIINNGG + The command argument to the --cc invocation option. + BBAASSHH__LLIINNEENNOO + An array variable whose members are the line numbers in source + files corresponding to each member of FFUUNNCCNNAAMMEE. + $${{BBAASSHH__LLIINNEENNOO[[_$_i]]}} is the line number in the source file where + $${{FFUUNNCCNNAAMMEE[[_$_i]]}} was called (or $${{BBAASSHH__LLIINNEENNOO[[_$_i_-_1]]}} if refer- + enced within another shell function). The corresponding source + file name is $${{BBAASSHH__SSOOUURRCCEE[[_$_i]]}}. Use LLIINNEENNOO to obtain the cur- + rent line number. + BBAASSHH__RREEMMAATTCCHH + An array variable whose members are assigned by the ==~~ binary + operator to the [[[[ conditional command. The element with index + 0 is the portion of the string matching the entire regular + expression. The element with index _n is the portion of the + string matching the _nth parenthesized subexpression. This vari- + able is read-only. + BBAASSHH__SSOOUURRCCEE + An array variable whose members are the source filenames corre- + sponding to the elements in the FFUUNNCCNNAAMMEE array variable. + BBAASSHH__SSUUBBSSHHEELLLL + Incremented by one each time a subshell or subshell environment + is spawned. The initial value is 0. + BBAASSHH__VVEERRSSIINNFFOO + A readonly array variable whose members hold version information + for this instance of bbaasshh. The values assigned to the array + members are as follows: + BBAASSHH__VVEERRSSIINNFFOO[[0]] The major version number (the _r_e_l_e_a_s_e). + BBAASSHH__VVEERRSSIINNFFOO[[1]] The minor version number (the _v_e_r_s_i_o_n). + BBAASSHH__VVEERRSSIINNFFOO[[2]] The patch level. + BBAASSHH__VVEERRSSIINNFFOO[[3]] The build version. + BBAASSHH__VVEERRSSIINNFFOO[[4]] The release status (e.g., _b_e_t_a_1). + BBAASSHH__VVEERRSSIINNFFOO[[5]] The value of MMAACCHHTTYYPPEE. + + BBAASSHH__VVEERRSSIIOONN + Expands to a string describing the version of this instance of + bbaasshh. + + CCOOMMPP__CCWWOORRDD + An index into $${{CCOOMMPP__WWOORRDDSS}} of the word containing the current + cursor position. This variable is available only in shell func- + tions invoked by the programmable completion facilities (see + PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). + + CCOOMMPP__KKEEYY + The key (or final key of a key sequence) used to invoke the cur- + rent completion function. + + CCOOMMPP__LLIINNEE + The current command line. This variable is available only in + shell functions and external commands invoked by the pro- + grammable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn + below). + + CCOOMMPP__PPOOIINNTT + The index of the current cursor position relative to the begin- + ning of the current command. If the current cursor position is + at the end of the current command, the value of this variable is + equal to $${{##CCOOMMPP__LLIINNEE}}. This variable is available only in + shell functions and external commands invoked by the pro- + grammable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn + below). + + CCOOMMPP__TTYYPPEE + Set to an integer value corresponding to the type of completion + attempted that caused a completion function to be called: _T_A_B, + for normal completion, _?, for listing completions after succes- + sive tabs, _!, for listing alternatives on partial word comple- + tion, _@, to list completions if the word is not unmodified, or + _%, for menu completion. This variable is available only in + shell functions and external commands invoked by the pro- + grammable completion facilities (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn + below). + + CCOOMMPP__WWOORRDDBBRREEAAKKSS + The set of characters that the rreeaaddlliinnee library treats as word + separators when performing word completion. If CCOOMMPP__WWOORRDDBBRREEAAKKSS + is unset, it loses its special properties, even if it is subse- + quently reset. + + CCOOMMPP__WWOORRDDSS + An array variable (see AArrrraayyss below) consisting of the individ- + ual words in the current command line. The line is split into + words as rreeaaddlliinnee would split it, using CCOOMMPP__WWOORRDDBBRREEAAKKSS as + described above. This variable is available only in shell func- + tions invoked by the programmable completion facilities (see + PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). + + DDIIRRSSTTAACCKK + An array variable (see AArrrraayyss below) containing the current con- + tents of the directory stack. Directories appear in the stack + in the order they are displayed by the ddiirrss builtin. Assigning + to members of this array variable may be used to modify directo- + ries already in the stack, but the ppuusshhdd and ppooppdd builtins must + be used to add and remove directories. Assignment to this vari- + able will not change the current directory. If DDIIRRSSTTAACCKK is + unset, it loses its special properties, even if it is subse- + quently reset. + + EEUUIIDD Expands to the effective user ID of the current user, initial- + ized at shell startup. This variable is readonly. + + FFUUNNCCNNAAMMEE + An array variable containing the names of all shell functions + currently in the execution call stack. The element with index 0 + is the name of any currently-executing shell function. The bot- + tom-most element is "main". This variable exists only when a + shell function is executing. Assignments to FFUUNNCCNNAAMMEE have no + effect and return an error status. If FFUUNNCCNNAAMMEE is unset, it + loses its special properties, even if it is subsequently reset. + + GGRROOUUPPSS An array variable containing the list of groups of which the + current user is a member. Assignments to GGRROOUUPPSS have no effect + and return an error status. If GGRROOUUPPSS is unset, it loses its + special properties, even if it is subsequently reset. + + HHIISSTTCCMMDD + The history number, or index in the history list, of the current + command. If HHIISSTTCCMMDD is unset, it loses its special properties, + even if it is subsequently reset. + + HHOOSSTTNNAAMMEE + Automatically set to the name of the current host. + + HHOOSSTTTTYYPPEE + Automatically set to a string that uniquely describes the type + of machine on which bbaasshh is executing. The default is system- + dependent. + + LLIINNEENNOO Each time this parameter is referenced, the shell substitutes a + decimal number representing the current sequential line number + (starting with 1) within a script or function. When not in a + script or function, the value substituted is not guaranteed to + be meaningful. If LLIINNEENNOO is unset, it loses its special proper- + ties, even if it is subsequently reset. + + MMAACCHHTTYYPPEE + Automatically set to a string that fully describes the system + type on which bbaasshh is executing, in the standard GNU _c_p_u_-_c_o_m_- + _p_a_n_y_-_s_y_s_t_e_m format. The default is system-dependent. + + OOLLDDPPWWDD The previous working directory as set by the ccdd command. + + OOPPTTAARRGG The value of the last option argument processed by the ggeettooppttss + builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + OOPPTTIINNDD The index of the next argument to be processed by the ggeettooppttss + builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + OOSSTTYYPPEE Automatically set to a string that describes the operating sys- + tem on which bbaasshh is executing. The default is system-depen- + dent. + + PPIIPPEESSTTAATTUUSS + An array variable (see AArrrraayyss below) containing a list of exit + status values from the processes in the most-recently-executed + foreground pipeline (which may contain only a single command). + + PPPPIIDD The process ID of the shell's parent. This variable is read- + only. + + PPWWDD The current working directory as set by the ccdd command. + + RRAANNDDOOMM Each time this parameter is referenced, a random integer between + 0 and 32767 is generated. The sequence of random numbers may be + initialized by assigning a value to RRAANNDDOOMM. If RRAANNDDOOMM is unset, + it loses its special properties, even if it is subsequently + reset. + + RREEPPLLYY Set to the line of input read by the rreeaadd builtin command when + no arguments are supplied. + + SSEECCOONNDDSS + Each time this parameter is referenced, the number of seconds + since shell invocation is returned. If a value is assigned to + SSEECCOONNDDSS, the value returned upon subsequent references is the + number of seconds since the assignment plus the value assigned. + If SSEECCOONNDDSS is unset, it loses its special properties, even if it + is subsequently reset. + + SSHHEELLLLOOPPTTSS + A colon-separated list of enabled shell options. Each word in + the list is a valid argument for the --oo option to the sseett + builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The options + appearing in SSHHEELLLLOOPPTTSS are those reported as _o_n by sseett --oo. If + this variable is in the environment when bbaasshh starts up, each + shell option in the list will be enabled before reading any + startup files. This variable is read-only. + + SSHHLLVVLL Incremented by one each time an instance of bbaasshh is started. + + UUIIDD Expands to the user ID of the current user, initialized at shell + startup. This variable is readonly. + + The following variables are used by the shell. In some cases, bbaasshh + assigns a default value to a variable; these cases are noted below. + + BBAASSHH__EENNVV + If this parameter is set when bbaasshh is executing a shell script, + its value is interpreted as a filename containing commands to + initialize the shell, as in _~_/_._b_a_s_h_r_c. The value of BBAASSHH__EENNVV is + subjected to parameter expansion, command substitution, and + arithmetic expansion before being interpreted as a file name. + PPAATTHH is not used to search for the resultant file name. + CCDDPPAATTHH The search path for the ccdd command. This is a colon-separated + list of directories in which the shell looks for destination + directories specified by the ccdd command. A sample value is + ".:~:/usr". + BBAASSHH__XXTTRRAACCEEFFDD + If set to an integer corresponding to a valid file descriptor, + bbaasshh will write the trace output generated when _s_e_t _-_x is + enabled to that file descriptor. The file descriptor is closed + when BBAASSHH__XXTTRRAACCEEFFDD is unset or assigned a new value. Unsetting + BBAASSHH__XXTTRRAACCEEFFDD or assigning it the empty string causes the trace + output to be sent to the standard error. Note that setting + BBAASSHH__XXTTRRAACCEEFFDD to 2 (the standard error file descriptor) and then + unsetting it will result in the standard error being closed. + CCOOLLUUMMNNSS + Used by the sseelleecctt builtin command to determine the terminal + width when printing selection lists. Automatically set upon + receipt of a SIGWINCH. + CCOOMMPPRREEPPLLYY + An array variable from which bbaasshh reads the possible completions + generated by a shell function invoked by the programmable com- + pletion facility (see PPrrooggrraammmmaabbllee CCoommpplleettiioonn below). + EEMMAACCSS If bbaasshh finds this variable in the environment when the shell + starts with value "t", it assumes that the shell is running in + an emacs shell buffer and disables line editing. + FFCCEEDDIITT The default editor for the ffcc builtin command. + FFIIGGNNOORREE + A colon-separated list of suffixes to ignore when performing + filename completion (see RREEAADDLLIINNEE below). A filename whose suf- + fix matches one of the entries in FFIIGGNNOORREE is excluded from the + list of matched filenames. A sample value is ".o:~". + GGLLOOBBIIGGNNOORREE + A colon-separated list of patterns defining the set of filenames + to be ignored by pathname expansion. If a filename matched by a + pathname expansion pattern also matches one of the patterns in + GGLLOOBBIIGGNNOORREE, it is removed from the list of matches. + HHIISSTTCCOONNTTRROOLL + A colon-separated list of values controlling how commands are + saved on the history list. If the list of values includes + _i_g_n_o_r_e_s_p_a_c_e, lines which begin with a ssppaaccee character are not + saved in the history list. A value of _i_g_n_o_r_e_d_u_p_s causes lines + matching the previous history entry to not be saved. A value of + _i_g_n_o_r_e_b_o_t_h is shorthand for _i_g_n_o_r_e_s_p_a_c_e and _i_g_n_o_r_e_d_u_p_s. A value + of _e_r_a_s_e_d_u_p_s causes all previous lines matching the current line + to be removed from the history list before that line is saved. + Any value not in the above list is ignored. If HHIISSTTCCOONNTTRROOLL is + unset, or does not include a valid value, all lines read by the + shell parser are saved on the history list, subject to the value + of HHIISSTTIIGGNNOORREE. The second and subsequent lines of a multi-line + compound command are not tested, and are added to the history + regardless of the value of HHIISSTTCCOONNTTRROOLL. + HHIISSTTFFIILLEE + The name of the file in which command history is saved (see HHIISS-- + TTOORRYY below). The default value is _~_/_._b_a_s_h___h_i_s_t_o_r_y. If unset, + the command history is not saved when an interactive shell + exits. + HHIISSTTFFIILLEESSIIZZEE + The maximum number of lines contained in the history file. When + this variable is assigned a value, the history file is trun- + cated, if necessary, by removing the oldest entries, to contain + no more than that number of lines. The default value is 500. + The history file is also truncated to this size after writing it + when an interactive shell exits. + HHIISSTTIIGGNNOORREE + A colon-separated list of patterns used to decide which command + lines should be saved on the history list. Each pattern is + anchored at the beginning of the line and must match the com- + plete line (no implicit `**' is appended). Each pattern is + tested against the line after the checks specified by HHIISSTTCCOONN-- + TTRROOLL are applied. In addition to the normal shell pattern + matching characters, `&&' matches the previous history line. `&&' + may be escaped using a backslash; the backslash is removed + before attempting a match. The second and subsequent lines of a + multi-line compound command are not tested, and are added to the + history regardless of the value of HHIISSTTIIGGNNOORREE. + HHIISSTTSSIIZZEE + The number of commands to remember in the command history (see + HHIISSTTOORRYY below). The default value is 500. + HHIISSTTTTIIMMEEFFOORRMMAATT + If this variable is set and not null, its value is used as a + format string for _s_t_r_f_t_i_m_e(3) to print the time stamp associated + with each history entry displayed by the hhiissttoorryy builtin. If + this variable is set, time stamps are written to the history + file so they may be preserved across shell sessions. This uses + the history comment character to distinguish timestamps from + other history lines. + HHOOMMEE The home directory of the current user; the default argument for + the ccdd builtin command. The value of this variable is also used + when performing tilde expansion. + HHOOSSTTFFIILLEE + Contains the name of a file in the same format as _/_e_t_c_/_h_o_s_t_s + that should be read when the shell needs to complete a hostname. + The list of possible hostname completions may be changed while + the shell is running; the next time hostname completion is + attempted after the value is changed, bbaasshh adds the contents of + the new file to the existing list. If HHOOSSTTFFIILLEE is set, but has + no value, or does not name a readable file, bbaasshh attempts to + read _/_e_t_c_/_h_o_s_t_s to obtain the list of possible hostname comple- + tions. When HHOOSSTTFFIILLEE is unset, the hostname list is cleared. + IIFFSS The _I_n_t_e_r_n_a_l _F_i_e_l_d _S_e_p_a_r_a_t_o_r that is used for word splitting + after expansion and to split lines into words with the rreeaadd + builtin command. The default value is ``<space><tab><new- + line>''. + IIGGNNOORREEEEOOFF + Controls the action of an interactive shell on receipt of an EEOOFF + character as the sole input. If set, the value is the number of + consecutive EEOOFF characters which must be typed as the first + characters on an input line before bbaasshh exits. If the variable + exists but does not have a numeric value, or has no value, the + default value is 10. If it does not exist, EEOOFF signifies the + end of input to the shell. + IINNPPUUTTRRCC + The filename for the rreeaaddlliinnee startup file, overriding the + default of _~_/_._i_n_p_u_t_r_c (see RREEAADDLLIINNEE below). + LLAANNGG Used to determine the locale category for any category not + specifically selected with a variable starting with LLCC__. + LLCC__AALLLL This variable overrides the value of LLAANNGG and any other LLCC__ + variable specifying a locale category. + LLCC__CCOOLLLLAATTEE + This variable determines the collation order used when sorting + the results of pathname expansion, and determines the behavior + of range expressions, equivalence classes, and collating + sequences within pathname expansion and pattern matching. + LLCC__CCTTYYPPEE + This variable determines the interpretation of characters and + the behavior of character classes within pathname expansion and + pattern matching. + LLCC__MMEESSSSAAGGEESS + This variable determines the locale used to translate double- + quoted strings preceded by a $$. + LLCC__NNUUMMEERRIICC + This variable determines the locale category used for number + formatting. + LLIINNEESS Used by the sseelleecctt builtin command to determine the column + length for printing selection lists. Automatically set upon + receipt of a SSIIGGWWIINNCCHH. + MMAAIILL If this parameter is set to a file name and the MMAAIILLPPAATTHH vari- + able is not set, bbaasshh informs the user of the arrival of mail in + the specified file. + MMAAIILLCCHHEECCKK + Specifies how often (in seconds) bbaasshh checks for mail. The + default is 60 seconds. When it is time to check for mail, the + shell does so before displaying the primary prompt. If this + variable is unset, or set to a value that is not a number + greater than or equal to zero, the shell disables mail checking. + MMAAIILLPPAATTHH + A colon-separated list of file names to be checked for mail. + The message to be printed when mail arrives in a particular file + may be specified by separating the file name from the message + with a `?'. When used in the text of the message, $$__ expands to + the name of the current mailfile. Example: + MMAAIILLPPAATTHH='/var/mail/bfox?"You have mail":~/shell-mail?"$_ has + mail!"' + BBaasshh supplies a default value for this variable, but the loca- + tion of the user mail files that it uses is system dependent + (e.g., /var/mail/$$UUSSEERR). + OOPPTTEERRRR If set to the value 1, bbaasshh displays error messages generated by + the ggeettooppttss builtin command (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + OOPPTTEERRRR is initialized to 1 each time the shell is invoked or a + shell script is executed. + PPAATTHH The search path for commands. It is a colon-separated list of + directories in which the shell looks for commands (see CCOOMMMMAANNDD + EEXXEECCUUTTIIOONN below). A zero-length (null) directory name in the + value of PPAATTHH indicates the current directory. A null directory + name may appear as two adjacent colons, or as an initial or + trailing colon. The default path is system-dependent, and is + set by the administrator who installs bbaasshh. A common value is + ``/usr/gnu/bin:/usr/local/bin:/usr/ucb:/bin:/usr/bin''. + PPOOSSIIXXLLYY__CCOORRRREECCTT + If this variable is in the environment when bbaasshh starts, the + shell enters _p_o_s_i_x _m_o_d_e before reading the startup files, as if + the ----ppoossiixx invocation option had been supplied. If it is set + while the shell is running, bbaasshh enables _p_o_s_i_x _m_o_d_e, as if the + command _s_e_t _-_o _p_o_s_i_x had been executed. + PPRROOMMPPTT__CCOOMMMMAANNDD + If set, the value is executed as a command prior to issuing each + primary prompt. + PPRROOMMPPTT__DDIIRRTTRRIIMM + If set to a number greater than zero, the value is used as the + number of trailing directory components to retain when expanding + the \\ww and \\WW prompt string escapes (see PPRROOMMPPTTIINNGG below). + Characters removed are replaced with an ellipsis. + PPSS11 The value of this parameter is expanded (see PPRROOMMPPTTIINNGG below) + and used as the primary prompt string. The default value is + ``\\ss--\\vv\\$$ ''. + PPSS22 The value of this parameter is expanded as with PPSS11 and used as + the secondary prompt string. The default is ``>> ''. + PPSS33 The value of this parameter is used as the prompt for the sseelleecctt + command (see SSHHEELLLL GGRRAAMMMMAARR above). + PPSS44 The value of this parameter is expanded as with PPSS11 and the + value is printed before each command bbaasshh displays during an + execution trace. The first character of PPSS44 is replicated mul- + tiple times, as necessary, to indicate multiple levels of indi- + rection. The default is ``++ ''. + SSHHEELLLL The full pathname to the shell is kept in this environment vari- + able. If it is not set when the shell starts, bbaasshh assigns to + it the full pathname of the current user's login shell. + TTIIMMEEFFOORRMMAATT + The value of this parameter is used as a format string specify- + ing how the timing information for pipelines prefixed with the + ttiimmee reserved word should be displayed. The %% character intro- + duces an escape sequence that is expanded to a time value or + other information. The escape sequences and their meanings are + as follows; the braces denote optional portions. + %%%% A literal %%. + %%[[_p]][[ll]]RR The elapsed time in seconds. + %%[[_p]][[ll]]UU The number of CPU seconds spent in user mode. + %%[[_p]][[ll]]SS The number of CPU seconds spent in system mode. + %%PP The CPU percentage, computed as (%U + %S) / %R. + + The optional _p is a digit specifying the _p_r_e_c_i_s_i_o_n, the number + of fractional digits after a decimal point. A value of 0 causes + no decimal point or fraction to be output. At most three places + after the decimal point may be specified; values of _p greater + than 3 are changed to 3. If _p is not specified, the value 3 is + used. + + The optional ll specifies a longer format, including minutes, of + the form _M_Mm_S_S._F_Fs. The value of _p determines whether or not + the fraction is included. + + If this variable is not set, bbaasshh acts as if it had the value + $$''\\nnrreeaall\\tt%%33llRR\\nnuusseerr\\tt%%33llUU\\nnssyyss%%33llSS''. If the value is null, no + timing information is displayed. A trailing newline is added + when the format string is displayed. + + TTMMOOUUTT If set to a value greater than zero, TTMMOOUUTT is treated as the + default timeout for the rreeaadd builtin. The sseelleecctt command termi- + nates if input does not arrive after TTMMOOUUTT seconds when input is + coming from a terminal. In an interactive shell, the value is + interpreted as the number of seconds to wait for input after + issuing the primary prompt. BBaasshh terminates after waiting for + that number of seconds if input does not arrive. + + TTMMPPDDIIRR If set, BBaasshh uses its value as the name of a directory in which + BBaasshh creates temporary files for the shell's use. + + aauuttoo__rreessuummee + This variable controls how the shell interacts with the user and + job control. If this variable is set, single word simple com- + mands without redirections are treated as candidates for resump- + tion of an existing stopped job. There is no ambiguity allowed; + if there is more than one job beginning with the string typed, + the job most recently accessed is selected. The _n_a_m_e of a + stopped job, in this context, is the command line used to start + it. If set to the value _e_x_a_c_t, the string supplied must match + the name of a stopped job exactly; if set to _s_u_b_s_t_r_i_n_g, the + string supplied needs to match a substring of the name of a + stopped job. The _s_u_b_s_t_r_i_n_g value provides functionality analo- + gous to the %%?? job identifier (see JJOOBB CCOONNTTRROOLL below). If set + to any other value, the supplied string must be a prefix of a + stopped job's name; this provides functionality analogous to the + %%_s_t_r_i_n_g job identifier. + + hhiissttcchhaarrss + The two or three characters which control history expansion and + tokenization (see HHIISSTTOORRYY EEXXPPAANNSSIIOONN below). The first character + is the _h_i_s_t_o_r_y _e_x_p_a_n_s_i_o_n character, the character which signals + the start of a history expansion, normally `!!'. The second + character is the _q_u_i_c_k _s_u_b_s_t_i_t_u_t_i_o_n character, which is used as + shorthand for re-running the previous command entered, substi- + tuting one string for another in the command. The default is + `^^'. The optional third character is the character which indi- + cates that the remainder of the line is a comment when found as + the first character of a word, normally `##'. The history com- + ment character causes history substitution to be skipped for the + remaining words on the line. It does not necessarily cause the + shell parser to treat the rest of the line as a comment. + + AArrrraayyss + BBaasshh provides one-dimensional indexed and associative array variables. + Any variable may be used as an indexed array; the ddeeccllaarree builtin will + explicitly declare an array. There is no maximum limit on the size of + an array, nor any requirement that members be indexed or assigned con- + tiguously. Indexed arrays are referenced using integers (including + arithmetic expressions) and are zero-based; associative arrays are + referenced using arbitrary strings. + + An indexed array is created automatically if any variable is assigned + to using the syntax _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e. The _s_u_b_s_c_r_i_p_t is treated as + an arithmetic expression that must evaluate to a number greater than or + equal to zero. To explicitly declare an indexed array, use ddeeccllaarree --aa + _n_a_m_e (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). ddeeccllaarree --aa _n_a_m_e[[_s_u_b_s_c_r_i_p_t]] is + also accepted; the _s_u_b_s_c_r_i_p_t is ignored. + + Associative arrays are created using ddeeccllaarree --AA _n_a_m_e. + + Attributes may be specified for an array variable using the ddeeccllaarree and + rreeaaddoonnllyy builtins. Each attribute applies to all members of an array. + + Arrays are assigned to using compound assignments of the form + _n_a_m_e=((value_1 ... value_n)), where each _v_a_l_u_e is of the form [_s_u_b_- + _s_c_r_i_p_t]=_s_t_r_i_n_g. Indexed array assignments do not require the bracket + and subscript. When assigning to indexed arrays, if the optional + brackets and subscript are supplied, that index is assigned to; other- + wise the index of the element assigned is the last index assigned to by + the statement plus one. Indexing starts at zero. + + When assigning to an associative array, the subscript is required. + + This syntax is also accepted by the ddeeccllaarree builtin. Individual array + elements may be assigned to using the _n_a_m_e[_s_u_b_s_c_r_i_p_t]=_v_a_l_u_e syntax + introduced above. + + Any element of an array may be referenced using ${_n_a_m_e[_s_u_b_s_c_r_i_p_t]}. + The braces are required to avoid conflicts with pathname expansion. If + _s_u_b_s_c_r_i_p_t is @@ or **, the word expands to all members of _n_a_m_e. These + subscripts differ only when the word appears within double quotes. If + the word is double-quoted, ${_n_a_m_e[*]} expands to a single word with the + value of each array member separated by the first character of the IIFFSS + special variable, and ${_n_a_m_e[@]} expands each element of _n_a_m_e to a sep- + arate word. When there are no array members, ${_n_a_m_e[@]} expands to + nothing. If the double-quoted expansion occurs within a word, the + expansion of the first parameter is joined with the beginning part of + the original word, and the expansion of the last parameter is joined + with the last part of the original word. This is analogous to the + expansion of the special parameters ** and @@ (see SSppeecciiaall PPaarraammeetteerrss + above). ${#_n_a_m_e[_s_u_b_s_c_r_i_p_t]} expands to the length of ${_n_a_m_e[_s_u_b_- + _s_c_r_i_p_t]}. If _s_u_b_s_c_r_i_p_t is ** or @@, the expansion is the number of ele- + ments in the array. Referencing an array variable without a subscript + is equivalent to referencing the array with a subscript of 0. + + An array variable is considered set if a subscript has been assigned a + value. The null string is a valid value. + + The uunnsseett builtin is used to destroy arrays. uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t] + destroys the array element at index _s_u_b_s_c_r_i_p_t. Care must be taken to + avoid unwanted side effects caused by pathname expansion. uunnsseett _n_a_m_e, + where _n_a_m_e is an array, or uunnsseett _n_a_m_e[_s_u_b_s_c_r_i_p_t], where _s_u_b_s_c_r_i_p_t is ** + or @@, removes the entire array. + + The ddeeccllaarree, llooccaall, and rreeaaddoonnllyy builtins each accept a --aa option to + specify an indexed array and a --AA option to specify an associative + array. The rreeaadd builtin accepts a --aa option to assign a list of words + read from the standard input to an array. The sseett and ddeeccllaarree builtins + display array values in a way that allows them to be reused as assign- + ments. + +EEXXPPAANNSSIIOONN + Expansion is performed on the command line after it has been split into + words. There are seven kinds of expansion performed: _b_r_a_c_e _e_x_p_a_n_s_i_o_n, + _t_i_l_d_e _e_x_p_a_n_s_i_o_n, _p_a_r_a_m_e_t_e_r _a_n_d _v_a_r_i_a_b_l_e _e_x_p_a_n_s_i_o_n, _c_o_m_m_a_n_d _s_u_b_s_t_i_t_u_- + _t_i_o_n, _a_r_i_t_h_m_e_t_i_c _e_x_p_a_n_s_i_o_n, _w_o_r_d _s_p_l_i_t_t_i_n_g, and _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n. + + The order of expansions is: brace expansion, tilde expansion, parame- + ter, variable and arithmetic expansion and command substitution (done + in a left-to-right fashion), word splitting, and pathname expansion. + + On systems that can support it, there is an additional expansion avail- + able: _p_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n. + + Only brace expansion, word splitting, and pathname expansion can change + the number of words of the expansion; other expansions expand a single + word to a single word. The only exceptions to this are the expansions + of "$$@@" and "$${{_n_a_m_e[[@@]]}}" as explained above (see PPAARRAAMMEETTEERRSS). + + BBrraaccee EExxppaannssiioonn + _B_r_a_c_e _e_x_p_a_n_s_i_o_n is a mechanism by which arbitrary strings may be gener- + ated. This mechanism is similar to _p_a_t_h_n_a_m_e _e_x_p_a_n_s_i_o_n, but the file- + names generated need not exist. Patterns to be brace expanded take the + form of an optional _p_r_e_a_m_b_l_e, followed by either a series of comma-sep- + arated strings or a sequence expression between a pair of braces, fol- + lowed by an optional _p_o_s_t_s_c_r_i_p_t. The preamble is prefixed to each + string contained within the braces, and the postscript is then appended + to each resulting string, expanding left to right. + + Brace expansions may be nested. The results of each expanded string + are not sorted; left to right order is preserved. For example, + a{{d,c,b}}e expands into `ade ace abe'. + + A sequence expression takes the form {{_x...._y[[...._i_n_c_r]]}}, where _x and _y are + either integers or single characters, and _i_n_c_r, an optional increment, + is an integer. When integers are supplied, the expression expands to + each number between _x and _y, inclusive. Supplied integers may be pre- + fixed with _0 to force each term to have the same width. When either _x + or _y begins with a zero, the shell attempts to force all generated + terms to contain the same number of digits, zero-padding where neces- + sary. When characters are supplied, the expression expands to each + character lexicographically between _x and _y, inclusive. Note that both + _x and _y must be of the same type. When the increment is supplied, it + is used as the difference between each term. The default increment is + 1 or -1 as appropriate. + + Brace expansion is performed before any other expansions, and any char- + acters special to other expansions are preserved in the result. It is + strictly textual. BBaasshh does not apply any syntactic interpretation to + the context of the expansion or the text between the braces. + + A correctly-formed brace expansion must contain unquoted opening and + closing braces, and at least one unquoted comma or a valid sequence + expression. Any incorrectly formed brace expansion is left unchanged. + A {{ or ,, may be quoted with a backslash to prevent its being considered + part of a brace expression. To avoid conflicts with parameter expan- + sion, the string $${{ is not considered eligible for brace expansion. + + This construct is typically used as shorthand when the common prefix of + the strings to be generated is longer than in the above example: + + mkdir /usr/local/src/bash/{old,new,dist,bugs} + or + chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} + + Brace expansion introduces a slight incompatibility with historical + versions of sshh. sshh does not treat opening or closing braces specially + when they appear as part of a word, and preserves them in the output. + BBaasshh removes braces from words as a consequence of brace expansion. + For example, a word entered to sshh as _f_i_l_e_{_1_,_2_} appears identically in + the output. The same word is output as _f_i_l_e_1 _f_i_l_e_2 after expansion by + bbaasshh. If strict compatibility with sshh is desired, start bbaasshh with the + ++BB option or disable brace expansion with the ++BB option to the sseett com- + mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + TTiillddee EExxppaannssiioonn + If a word begins with an unquoted tilde character (`~~'), all of the + characters preceding the first unquoted slash (or all characters, if + there is no unquoted slash) are considered a _t_i_l_d_e_-_p_r_e_f_i_x. If none of + the characters in the tilde-prefix are quoted, the characters in the + tilde-prefix following the tilde are treated as a possible _l_o_g_i_n _n_a_m_e. + If this login name is the null string, the tilde is replaced with the + value of the shell parameter HHOOMMEE. If HHOOMMEE is unset, the home direc- + tory of the user executing the shell is substituted instead. Other- + wise, the tilde-prefix is replaced with the home directory associated + with the specified login name. + + If the tilde-prefix is a `~+', the value of the shell variable PPWWDD + replaces the tilde-prefix. If the tilde-prefix is a `~-', the value of + the shell variable OOLLDDPPWWDD, if it is set, is substituted. If the char- + acters following the tilde in the tilde-prefix consist of a number _N, + optionally prefixed by a `+' or a `-', the tilde-prefix is replaced + with the corresponding element from the directory stack, as it would be + displayed by the ddiirrss builtin invoked with the tilde-prefix as an argu- + ment. If the characters following the tilde in the tilde-prefix con- + sist of a number without a leading `+' or `-', `+' is assumed. + + If the login name is invalid, or the tilde expansion fails, the word is + unchanged. + + Each variable assignment is checked for unquoted tilde-prefixes immedi- + ately following a :: or the first ==. In these cases, tilde expansion is + also performed. Consequently, one may use file names with tildes in + assignments to PPAATTHH, MMAAIILLPPAATTHH, and CCDDPPAATTHH, and the shell assigns the + expanded value. + + PPaarraammeetteerr EExxppaannssiioonn + The `$$' character introduces parameter expansion, command substitution, + or arithmetic expansion. The parameter name or symbol to be expanded + may be enclosed in braces, which are optional but serve to protect the + variable to be expanded from characters immediately following it which + could be interpreted as part of the name. + + When braces are used, the matching ending brace is the first `}}' not + escaped by a backslash or within a quoted string, and not within an + embedded arithmetic expansion, command substitution, or parameter + expansion. + + ${_p_a_r_a_m_e_t_e_r} + The value of _p_a_r_a_m_e_t_e_r is substituted. The braces are required + when _p_a_r_a_m_e_t_e_r is a positional parameter with more than one + digit, or when _p_a_r_a_m_e_t_e_r is followed by a character which is not + to be interpreted as part of its name. + + If the first character of _p_a_r_a_m_e_t_e_r is an exclamation point (!!), a + level of variable indirection is introduced. BBaasshh uses the value of + the variable formed from the rest of _p_a_r_a_m_e_t_e_r as the name of the vari- + able; this variable is then expanded and that value is used in the rest + of the substitution, rather than the value of _p_a_r_a_m_e_t_e_r itself. This + is known as _i_n_d_i_r_e_c_t _e_x_p_a_n_s_i_o_n. The exceptions to this are the expan- + sions of ${!_p_r_e_f_i_x*} and ${!!_n_a_m_e[_@]} described below. The exclamation + point must immediately follow the left brace in order to introduce + indirection. + + In each of the cases below, _w_o_r_d is subject to tilde expansion, parame- + ter expansion, command substitution, and arithmetic expansion. + + When not performing substring expansion, using the forms documented + below, bbaasshh tests for a parameter that is unset or null. Omitting the + colon results in a test only for a parameter that is unset. + + ${_p_a_r_a_m_e_t_e_r::--_w_o_r_d} + UUssee DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the expan- + sion of _w_o_r_d is substituted. Otherwise, the value of _p_a_r_a_m_e_t_e_r + is substituted. + ${_p_a_r_a_m_e_t_e_r::==_w_o_r_d} + AAssssiiggnn DDeeffaauulltt VVaalluueess. If _p_a_r_a_m_e_t_e_r is unset or null, the + expansion of _w_o_r_d is assigned to _p_a_r_a_m_e_t_e_r. The value of _p_a_r_a_m_- + _e_t_e_r is then substituted. Positional parameters and special + parameters may not be assigned to in this way. + ${_p_a_r_a_m_e_t_e_r::??_w_o_r_d} + DDiissppllaayy EErrrroorr iiff NNuullll oorr UUnnsseett. If _p_a_r_a_m_e_t_e_r is null or unset, + the expansion of _w_o_r_d (or a message to that effect if _w_o_r_d is + not present) is written to the standard error and the shell, if + it is not interactive, exits. Otherwise, the value of _p_a_r_a_m_e_t_e_r + is substituted. + ${_p_a_r_a_m_e_t_e_r::++_w_o_r_d} + UUssee AAlltteerrnnaattee VVaalluuee. If _p_a_r_a_m_e_t_e_r is null or unset, nothing is + substituted, otherwise the expansion of _w_o_r_d is substituted. + ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t} + ${_p_a_r_a_m_e_t_e_r::_o_f_f_s_e_t::_l_e_n_g_t_h} + SSuubbssttrriinngg EExxppaannssiioonn.. Expands to up to _l_e_n_g_t_h characters of + _p_a_r_a_m_e_t_e_r starting at the character specified by _o_f_f_s_e_t. If + _l_e_n_g_t_h is omitted, expands to the substring of _p_a_r_a_m_e_t_e_r start- + ing at the character specified by _o_f_f_s_e_t. _l_e_n_g_t_h and _o_f_f_s_e_t are + arithmetic expressions (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN below). + _l_e_n_g_t_h must evaluate to a number greater than or equal to zero. + If _o_f_f_s_e_t evaluates to a number less than zero, the value is + used as an offset from the end of the value of _p_a_r_a_m_e_t_e_r. If + _p_a_r_a_m_e_t_e_r is @@, the result is _l_e_n_g_t_h positional parameters + beginning at _o_f_f_s_e_t. If _p_a_r_a_m_e_t_e_r is an indexed array name sub- + scripted by @ or *, the result is the _l_e_n_g_t_h members of the + array beginning with ${_p_a_r_a_m_e_t_e_r[_o_f_f_s_e_t]}. A negative _o_f_f_s_e_t is + taken relative to one greater than the maximum index of the + specified array. Substring expansion applied to an associative + array produces undefined results. Note that a negative offset + must be separated from the colon by at least one space to avoid + being confused with the :- expansion. Substring indexing is + zero-based unless the positional parameters are used, in which + case the indexing starts at 1 by default. If _o_f_f_s_e_t is 0, and + the positional parameters are used, $$00 is prefixed to the list. + + ${!!_p_r_e_f_i_x**} + ${!!_p_r_e_f_i_x@@} + NNaammeess mmaattcchhiinngg pprreeffiixx.. Expands to the names of variables whose + names begin with _p_r_e_f_i_x, separated by the first character of the + IIFFSS special variable. When _@ is used and the expansion appears + within double quotes, each variable name expands to a separate + word. + + ${!!_n_a_m_e[_@]} + ${!!_n_a_m_e[_*]} + LLiisstt ooff aarrrraayy kkeeyyss.. If _n_a_m_e is an array variable, expands to + the list of array indices (keys) assigned in _n_a_m_e. If _n_a_m_e is + not an array, expands to 0 if _n_a_m_e is set and null otherwise. + When _@ is used and the expansion appears within double quotes, + each key expands to a separate word. + + ${##_p_a_r_a_m_e_t_e_r} + PPaarraammeetteerr lleennggtthh.. The length in characters of the value of + _p_a_r_a_m_e_t_e_r is substituted. If _p_a_r_a_m_e_t_e_r is ** or @@, the value + substituted is the number of positional parameters. If _p_a_r_a_m_e_- + _t_e_r is an array name subscripted by ** or @@, the value substi- + tuted is the number of elements in the array. + + ${_p_a_r_a_m_e_t_e_r##_w_o_r_d} + ${_p_a_r_a_m_e_t_e_r####_w_o_r_d} + RReemmoovvee mmaattcchhiinngg pprreeffiixx ppaatttteerrnn.. The _w_o_r_d is expanded to produce + a pattern just as in pathname expansion. If the pattern matches + the beginning of the value of _p_a_r_a_m_e_t_e_r, then the result of the + expansion is the expanded value of _p_a_r_a_m_e_t_e_r with the shortest + matching pattern (the ``##'' case) or the longest matching pat- + tern (the ``####'' case) deleted. If _p_a_r_a_m_e_t_e_r is @@ or **, the + pattern removal operation is applied to each positional parame- + ter in turn, and the expansion is the resultant list. If _p_a_r_a_m_- + _e_t_e_r is an array variable subscripted with @@ or **, the pattern + removal operation is applied to each member of the array in + turn, and the expansion is the resultant list. + + ${_p_a_r_a_m_e_t_e_r%%_w_o_r_d} + ${_p_a_r_a_m_e_t_e_r%%%%_w_o_r_d} + RReemmoovvee mmaattcchhiinngg ssuuffffiixx ppaatttteerrnn.. The _w_o_r_d is expanded to produce + a pattern just as in pathname expansion. If the pattern matches + a trailing portion of the expanded value of _p_a_r_a_m_e_t_e_r, then the + result of the expansion is the expanded value of _p_a_r_a_m_e_t_e_r with + the shortest matching pattern (the ``%%'' case) or the longest + matching pattern (the ``%%%%'' case) deleted. If _p_a_r_a_m_e_t_e_r is @@ + or **, the pattern removal operation is applied to each posi- + tional parameter in turn, and the expansion is the resultant + list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted with @@ or + **, the pattern removal operation is applied to each member of + the array in turn, and the expansion is the resultant list. + + ${_p_a_r_a_m_e_t_e_r//_p_a_t_t_e_r_n//_s_t_r_i_n_g} + PPaatttteerrnn ssuubbssttiittuuttiioonn.. The _p_a_t_t_e_r_n is expanded to produce a pat- + tern just as in pathname expansion. _P_a_r_a_m_e_t_e_r is expanded and + the longest match of _p_a_t_t_e_r_n against its value is replaced with + _s_t_r_i_n_g. If _p_a_t_t_e_r_n begins with //, all matches of _p_a_t_t_e_r_n are + replaced with _s_t_r_i_n_g. Normally only the first match is + replaced. If _p_a_t_t_e_r_n begins with ##, it must match at the begin- + ning of the expanded value of _p_a_r_a_m_e_t_e_r. If _p_a_t_t_e_r_n begins with + %%, it must match at the end of the expanded value of _p_a_r_a_m_e_t_e_r. + If _s_t_r_i_n_g is null, matches of _p_a_t_t_e_r_n are deleted and the // fol- + lowing _p_a_t_t_e_r_n may be omitted. If _p_a_r_a_m_e_t_e_r is @@ or **, the sub- + stitution operation is applied to each positional parameter in + turn, and the expansion is the resultant list. If _p_a_r_a_m_e_t_e_r is + an array variable subscripted with @@ or **, the substitution + operation is applied to each member of the array in turn, and + the expansion is the resultant list. + + ${_p_a_r_a_m_e_t_e_r^^_p_a_t_t_e_r_n} + ${_p_a_r_a_m_e_t_e_r^^^^_p_a_t_t_e_r_n} + ${_p_a_r_a_m_e_t_e_r,,_p_a_t_t_e_r_n} + ${_p_a_r_a_m_e_t_e_r,,,,_p_a_t_t_e_r_n} + CCaassee mmooddiiffiiccaattiioonn.. This expansion modifies the case of alpha- + betic characters in _p_a_r_a_m_e_t_e_r. The _p_a_t_t_e_r_n is expanded to pro- + duce a pattern just as in pathname expansion. The ^^ operator + converts lowercase letters matching _p_a_t_t_e_r_n to uppercase; the ,, + operator converts matching uppercase letters to lowercase. The + ^^^^ and ,,,, expansions convert each matched character in the + expanded value; the ^^ and ,, expansions match and convert only + the first character in the expanded value.. If _p_a_t_t_e_r_n is omit- + ted, it is treated like a ??, which matches every character. If + _p_a_r_a_m_e_t_e_r is @@ or **, the case modification operation is applied + to each positional parameter in turn, and the expansion is the + resultant list. If _p_a_r_a_m_e_t_e_r is an array variable subscripted + with @@ or **, the case modification operation is applied to each + member of the array in turn, and the expansion is the resultant + list. + + CCoommmmaanndd SSuubbssttiittuuttiioonn + _C_o_m_m_a_n_d _s_u_b_s_t_i_t_u_t_i_o_n allows the output of a command to replace the com- + mand name. There are two forms: + + + $$((_c_o_m_m_a_n_d)) + or + ``_c_o_m_m_a_n_d`` + + BBaasshh performs the expansion by executing _c_o_m_m_a_n_d and replacing the com- + mand substitution with the standard output of the command, with any + trailing newlines deleted. Embedded newlines are not deleted, but they + may be removed during word splitting. The command substitution $$((ccaatt + _f_i_l_e)) can be replaced by the equivalent but faster $$((<< _f_i_l_e)). + + When the old-style backquote form of substitution is used, backslash + retains its literal meaning except when followed by $$, ``, or \\. The + first backquote not preceded by a backslash terminates the command sub- + stitution. When using the $(_c_o_m_m_a_n_d) form, all characters between the + parentheses make up the command; none are treated specially. + + Command substitutions may be nested. To nest when using the backquoted + form, escape the inner backquotes with backslashes. + + If the substitution appears within double quotes, word splitting and + pathname expansion are not performed on the results. + + AArriitthhmmeettiicc EExxppaannssiioonn + Arithmetic expansion allows the evaluation of an arithmetic expression + and the substitution of the result. The format for arithmetic expan- + sion is: + + $$((((_e_x_p_r_e_s_s_i_o_n)))) + + The _e_x_p_r_e_s_s_i_o_n is treated as if it were within double quotes, but a + double quote inside the parentheses is not treated specially. All + tokens in the expression undergo parameter expansion, string expansion, + command substitution, and quote removal. Arithmetic expansions may be + nested. + + The evaluation is performed according to the rules listed below under + AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN. If _e_x_p_r_e_s_s_i_o_n is invalid, bbaasshh prints a message + indicating failure and no substitution occurs. + + PPrroocceessss SSuubbssttiittuuttiioonn + _P_r_o_c_e_s_s _s_u_b_s_t_i_t_u_t_i_o_n is supported on systems that support named pipes + (_F_I_F_O_s) or the //ddeevv//ffdd method of naming open files. It takes the form + of <<((_l_i_s_t)) or >>((_l_i_s_t)). The process _l_i_s_t is run with its input or out- + put connected to a _F_I_F_O or some file in //ddeevv//ffdd. The name of this file + is passed as an argument to the current command as the result of the + expansion. If the >>((_l_i_s_t)) form is used, writing to the file will pro- + vide input for _l_i_s_t. If the <<((_l_i_s_t)) form is used, the file passed as + an argument should be read to obtain the output of _l_i_s_t. + + When available, process substitution is performed simultaneously with + parameter and variable expansion, command substitution, and arithmetic + expansion. + + WWoorrdd SSpplliittttiinngg + The shell scans the results of parameter expansion, command substitu- + tion, and arithmetic expansion that did not occur within double quotes + for _w_o_r_d _s_p_l_i_t_t_i_n_g. + + The shell treats each character of IIFFSS as a delimiter, and splits the + results of the other expansions into words on these characters. If IIFFSS + is unset, or its value is exactly <<ssppaaccee>><<ttaabb>><<nneewwlliinnee>>, the default, + then sequences of <<ssppaaccee>>, <<ttaabb>>, and <<nneewwlliinnee>> at the beginning and + end of the results of the previous expansions are ignored, and any + sequence of IIFFSS characters not at the beginning or end serves to + delimit words. If IIFFSS has a value other than the default, then + sequences of the whitespace characters ssppaaccee and ttaabb are ignored at the + beginning and end of the word, as long as the whitespace character is + in the value of IIFFSS (an IIFFSS whitespace character). Any character in + IIFFSS that is not IIFFSS whitespace, along with any adjacent IIFFSS whitespace + characters, delimits a field. A sequence of IIFFSS whitespace characters + is also treated as a delimiter. If the value of IIFFSS is null, no word + splitting occurs. + + Explicit null arguments ("""" or '''') are retained. Unquoted implicit + null arguments, resulting from the expansion of parameters that have no + values, are removed. If a parameter with no value is expanded within + double quotes, a null argument results and is retained. + + Note that if no expansion occurs, no splitting is performed. + + PPaatthhnnaammee EExxppaannssiioonn + After word splitting, unless the --ff option has been set, bbaasshh scans + each word for the characters **, ??, and [[. If one of these characters + appears, then the word is regarded as a _p_a_t_t_e_r_n, and replaced with an + alphabetically sorted list of file names matching the pattern. If no + matching file names are found, and the shell option nnuullllgglloobb is not + enabled, the word is left unchanged. If the nnuullllgglloobb option is set, + and no matches are found, the word is removed. If the ffaaiillgglloobb shell + option is set, and no matches are found, an error message is printed + and the command is not executed. If the shell option nnooccaasseegglloobb is + enabled, the match is performed without regard to the case of alpha- + betic characters. When a pattern is used for pathname expansion, the + character ````..'''' at the start of a name or immediately following a + slash must be matched explicitly, unless the shell option ddoottgglloobb is + set. When matching a pathname, the slash character must always be + matched explicitly. In other cases, the ````..'''' character is not + treated specially. See the description of sshhoopptt below under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS for a description of the nnooccaasseegglloobb, nnuullllgglloobb, ffaaiill-- + gglloobb, and ddoottgglloobb shell options. + + The GGLLOOBBIIGGNNOORREE shell variable may be used to restrict the set of file + names matching a _p_a_t_t_e_r_n. If GGLLOOBBIIGGNNOORREE is set, each matching file + name that also matches one of the patterns in GGLLOOBBIIGGNNOORREE is removed + from the list of matches. The file names ````..'''' and ````....'''' are always + ignored when GGLLOOBBIIGGNNOORREE is set and not null. However, setting GGLLOOBBIIGG-- + NNOORREE to a non-null value has the effect of enabling the ddoottgglloobb shell + option, so all other file names beginning with a ````..'''' will match. To + get the old behavior of ignoring file names beginning with a ````..'''', + make ````..**'''' one of the patterns in GGLLOOBBIIGGNNOORREE. The ddoottgglloobb option is + disabled when GGLLOOBBIIGGNNOORREE is unset. + + PPaatttteerrnn MMaattcchhiinngg + + Any character that appears in a pattern, other than the special pattern + characters described below, matches itself. The NUL character may not + occur in a pattern. A backslash escapes the following character; the + escaping backslash is discarded when matching. The special pattern + characters must be quoted if they are to be matched literally. + + The special pattern characters have the following meanings: + + ** Matches any string, including the null string. When the gglloobb-- + ssttaarr shell option is enabled, and ** is used in a pathname expan- + sion context, two adjacent **s used as a single pattern will + match all files and zero or more directories and subdirectories. + If followed by a //, two adjacent **s will match only directories + and subdirectories. + ?? Matches any single character. + [[......]] Matches any one of the enclosed characters. A pair of charac- + ters separated by a hyphen denotes a _r_a_n_g_e _e_x_p_r_e_s_s_i_o_n; any char- + acter that sorts between those two characters, inclusive, using + the current locale's collating sequence and character set, is + matched. If the first character following the [[ is a !! or a ^^ + then any character not enclosed is matched. The sorting order + of characters in range expressions is determined by the current + locale and the value of the LLCC__CCOOLLLLAATTEE shell variable, if set. + A -- may be matched by including it as the first or last charac- + ter in the set. A ]] may be matched by including it as the first + character in the set. + + Within [[ and ]], _c_h_a_r_a_c_t_e_r _c_l_a_s_s_e_s can be specified using the + syntax [[::_c_l_a_s_s::]], where _c_l_a_s_s is one of the following classes + defined in the POSIX standard: + aallnnuumm aallpphhaa aasscciiii bbllaannkk ccnnttrrll ddiiggiitt ggrraapphh lloowweerr pprriinntt ppuunncctt + ssppaaccee uuppppeerr wwoorrdd xxddiiggiitt + A character class matches any character belonging to that class. + The wwoorrdd character class matches letters, digits, and the char- + acter _. + + Within [[ and ]], an _e_q_u_i_v_a_l_e_n_c_e _c_l_a_s_s can be specified using the + syntax [[==_c==]], which matches all characters with the same colla- + tion weight (as defined by the current locale) as the character + _c. + + Within [[ and ]], the syntax [[.._s_y_m_b_o_l..]] matches the collating sym- + bol _s_y_m_b_o_l. + + If the eexxttgglloobb shell option is enabled using the sshhoopptt builtin, several + extended pattern matching operators are recognized. In the following + description, a _p_a_t_t_e_r_n_-_l_i_s_t is a list of one or more patterns separated + by a ||. Composite patterns may be formed using one or more of the fol- + lowing sub-patterns: + + ??((_p_a_t_t_e_r_n_-_l_i_s_t)) + Matches zero or one occurrence of the given patterns + **((_p_a_t_t_e_r_n_-_l_i_s_t)) + Matches zero or more occurrences of the given patterns + ++((_p_a_t_t_e_r_n_-_l_i_s_t)) + Matches one or more occurrences of the given patterns + @@((_p_a_t_t_e_r_n_-_l_i_s_t)) + Matches one of the given patterns + !!((_p_a_t_t_e_r_n_-_l_i_s_t)) + Matches anything except one of the given patterns + + QQuuoottee RReemmoovvaall + After the preceding expansions, all unquoted occurrences of the charac- + ters \\, '', and "" that did not result from one of the above expansions + are removed. + +RREEDDIIRREECCTTIIOONN + Before a command is executed, its input and output may be _r_e_d_i_r_e_c_t_e_d + using a special notation interpreted by the shell. Redirection may + also be used to open and close files for the current shell execution + environment. The following redirection operators may precede or appear + anywhere within a _s_i_m_p_l_e _c_o_m_m_a_n_d or may follow a _c_o_m_m_a_n_d. Redirections + are processed in the order they appear, from left to right. + + Each redirection that may be preceded by a file descriptor number may + instead be preceded by a word of the form {_v_a_r_n_a_m_e}. In this case, for + each redirection operator except >&- and <&-, the shell will allocate a + file descriptor greater than 10 and assign it to _v_a_r_n_a_m_e. If >&- or + <&- is preceded by {_v_a_r_n_a_m_e}, the value of _v_a_r_n_a_m_e defines the file + descriptor to close. + + In the following descriptions, if the file descriptor number is omit- + ted, and the first character of the redirection operator is <<, the re- + direction refers to the standard input (file descriptor 0). If the + first character of the redirection operator is >>, the redirection + refers to the standard output (file descriptor 1). + + The word following the redirection operator in the following descrip- + tions, unless otherwise noted, is subjected to brace expansion, tilde + expansion, parameter expansion, command substitution, arithmetic expan- + sion, quote removal, pathname expansion, and word splitting. If it + expands to more than one word, bbaasshh reports an error. + + Note that the order of redirections is significant. For example, the + command + + ls >> dirlist 2>>&&1 + + directs both standard output and standard error to the file _d_i_r_l_i_s_t, + while the command + + ls 2>>&&1 >> dirlist + + directs only the standard output to file _d_i_r_l_i_s_t, because the standard + error was duplicated from the standard output before the standard out- + put was redirected to _d_i_r_l_i_s_t. + + BBaasshh handles several filenames specially when they are used in redirec- + tions, as described in the following table: + + //ddeevv//ffdd//_f_d + If _f_d is a valid integer, file descriptor _f_d is dupli- + cated. + //ddeevv//ssttddiinn + File descriptor 0 is duplicated. + //ddeevv//ssttddoouutt + File descriptor 1 is duplicated. + //ddeevv//ssttddeerrrr + File descriptor 2 is duplicated. + //ddeevv//ttccpp//_h_o_s_t//_p_o_r_t + If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t + is an integer port number or service name, bbaasshh attempts + to open a TCP connection to the corresponding socket. + //ddeevv//uuddpp//_h_o_s_t//_p_o_r_t + If _h_o_s_t is a valid hostname or Internet address, and _p_o_r_t + is an integer port number or service name, bbaasshh attempts + to open a UDP connection to the corresponding socket. + + A failure to open or create a file causes the redirection to fail. + + Redirections using file descriptors greater than 9 should be used with + care, as they may conflict with file descriptors the shell uses inter- + nally. + + RReeddiirreeccttiinngg IInnppuutt + Redirection of input causes the file whose name results from the expan- + sion of _w_o_r_d to be opened for reading on file descriptor _n, or the + standard input (file descriptor 0) if _n is not specified. + + The general format for redirecting input is: + + [_n]<<_w_o_r_d + + RReeddiirreeccttiinngg OOuuttppuutt + Redirection of output causes the file whose name results from the + expansion of _w_o_r_d to be opened for writing on file descriptor _n, or the + standard output (file descriptor 1) if _n is not specified. If the file + does not exist it is created; if it does exist it is truncated to zero + size. + + The general format for redirecting output is: + + [_n]>>_w_o_r_d + + If the redirection operator is >>, and the nnoocclloobbbbeerr option to the sseett + builtin has been enabled, the redirection will fail if the file whose + name results from the expansion of _w_o_r_d exists and is a regular file. + If the redirection operator is >>||, or the redirection operator is >> and + the nnoocclloobbbbeerr option to the sseett builtin command is not enabled, the re- + direction is attempted even if the file named by _w_o_r_d exists. + + AAppppeennddiinngg RReeddiirreecctteedd OOuuttppuutt + Redirection of output in this fashion causes the file whose name + results from the expansion of _w_o_r_d to be opened for appending on file + descriptor _n, or the standard output (file descriptor 1) if _n is not + specified. If the file does not exist it is created. + + The general format for appending output is: + + [_n]>>>>_w_o_r_d + + + RReeddiirreeccttiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr + This construct allows both the standard output (file descriptor 1) and + the standard error output (file descriptor 2) to be redirected to the + file whose name is the expansion of _w_o_r_d. + + There are two formats for redirecting standard output and standard + error: + + &&>>_w_o_r_d + and + >>&&_w_o_r_d + + Of the two forms, the first is preferred. This is semantically equiva- + lent to + + >>_w_o_r_d 2>>&&1 + + + AAppppeennddiinngg SSttaannddaarrdd OOuuttppuutt aanndd SSttaannddaarrdd EErrrroorr + This construct allows both the standard output (file descriptor 1) and + the standard error output (file descriptor 2) to be appended to the + file whose name is the expansion of _w_o_r_d. + + The format for appending standard output and standard error is: + + &&>>>>_w_o_r_d + + This is semantically equivalent to + + >>>>_w_o_r_d 2>>&&1 + + HHeerree DDooccuummeennttss + This type of redirection instructs the shell to read input from the + current source until a line containing only _d_e_l_i_m_i_t_e_r (with no trailing + blanks) is seen. All of the lines read up to that point are then used + as the standard input for a command. + + The format of here-documents is: + + <<<<[--]_w_o_r_d + _h_e_r_e_-_d_o_c_u_m_e_n_t + _d_e_l_i_m_i_t_e_r + + No parameter expansion, command substitution, arithmetic expansion, or + pathname expansion is performed on _w_o_r_d. If any characters in _w_o_r_d are + quoted, the _d_e_l_i_m_i_t_e_r is the result of quote removal on _w_o_r_d, and the + lines in the here-document are not expanded. If _w_o_r_d is unquoted, all + lines of the here-document are subjected to parameter expansion, com- + mand substitution, and arithmetic expansion. In the latter case, the + character sequence \\<<nneewwlliinnee>> is ignored, and \\ must be used to quote + the characters \\, $$, and ``. + + If the redirection operator is <<<<--, then all leading tab characters are + stripped from input lines and the line containing _d_e_l_i_m_i_t_e_r. This + allows here-documents within shell scripts to be indented in a natural + fashion. + + HHeerree SSttrriinnggss + A variant of here documents, the format is: + + <<<<<<_w_o_r_d + + The _w_o_r_d is expanded and supplied to the command on its standard input. + + DDuupplliiccaattiinngg FFiillee DDeessccrriippttoorrss + The redirection operator + + [_n]<<&&_w_o_r_d + + is used to duplicate input file descriptors. If _w_o_r_d expands to one or + more digits, the file descriptor denoted by _n is made to be a copy of + that file descriptor. If the digits in _w_o_r_d do not specify a file + descriptor open for input, a redirection error occurs. If _w_o_r_d evalu- + ates to --, file descriptor _n is closed. If _n is not specified, the + standard input (file descriptor 0) is used. + + The operator + + [_n]>>&&_w_o_r_d + + is used similarly to duplicate output file descriptors. If _n is not + specified, the standard output (file descriptor 1) is used. If the + digits in _w_o_r_d do not specify a file descriptor open for output, a re- + direction error occurs. As a special case, if _n is omitted, and _w_o_r_d + does not expand to one or more digits, the standard output and standard + error are redirected as described previously. + + MMoovviinngg FFiillee DDeessccrriippttoorrss + The redirection operator + + [_n]<<&&_d_i_g_i_t-- + + moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard + input (file descriptor 0) if _n is not specified. _d_i_g_i_t is closed after + being duplicated to _n. + + Similarly, the redirection operator + + [_n]>>&&_d_i_g_i_t-- + + moves the file descriptor _d_i_g_i_t to file descriptor _n, or the standard + output (file descriptor 1) if _n is not specified. + + OOppeenniinngg FFiillee DDeessccrriippttoorrss ffoorr RReeaaddiinngg aanndd WWrriittiinngg + The redirection operator + + [_n]<<>>_w_o_r_d + + causes the file whose name is the expansion of _w_o_r_d to be opened for + both reading and writing on file descriptor _n, or on file descriptor 0 + if _n is not specified. If the file does not exist, it is created. + +AALLIIAASSEESS + _A_l_i_a_s_e_s allow a string to be substituted for a word when it is used as + the first word of a simple command. The shell maintains a list of + aliases that may be set and unset with the aalliiaass and uunnaalliiaass builtin + commands (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). The first word of each + simple command, if unquoted, is checked to see if it has an alias. If + so, that word is replaced by the text of the alias. The characters //, + $$, ``, and == and any of the shell _m_e_t_a_c_h_a_r_a_c_t_e_r_s or quoting characters + listed above may not appear in an alias name. The replacement text may + contain any valid shell input, including shell metacharacters. The + first word of the replacement text is tested for aliases, but a word + that is identical to an alias being expanded is not expanded a second + time. This means that one may alias llss to llss --FF, for instance, and + bbaasshh does not try to recursively expand the replacement text. If the + last character of the alias value is a _b_l_a_n_k, then the next command + word following the alias is also checked for alias expansion. + + Aliases are created and listed with the aalliiaass command, and removed with + the uunnaalliiaass command. + + There is no mechanism for using arguments in the replacement text. If + arguments are needed, a shell function should be used (see FFUUNNCCTTIIOONNSS + below). + + Aliases are not expanded when the shell is not interactive, unless the + eexxppaanndd__aalliiaasseess shell option is set using sshhoopptt (see the description of + sshhoopptt under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + The rules concerning the definition and use of aliases are somewhat + confusing. BBaasshh always reads at least one complete line of input + before executing any of the commands on that line. Aliases are + expanded when a command is read, not when it is executed. Therefore, + an alias definition appearing on the same line as another command does + not take effect until the next line of input is read. The commands + following the alias definition on that line are not affected by the new + alias. This behavior is also an issue when functions are executed. + Aliases are expanded when a function definition is read, not when the + function is executed, because a function definition is itself a com- + pound command. As a consequence, aliases defined in a function are not + available until after that function is executed. To be safe, always + put alias definitions on a separate line, and do not use aalliiaass in com- + pound commands. + + For almost every purpose, aliases are superseded by shell functions. + +FFUUNNCCTTIIOONNSS + A shell function, defined as described above under SSHHEELLLL GGRRAAMMMMAARR, + stores a series of commands for later execution. When the name of a + shell function is used as a simple command name, the list of commands + associated with that function name is executed. Functions are executed + in the context of the current shell; no new process is created to + interpret them (contrast this with the execution of a shell script). + When a function is executed, the arguments to the function become the + positional parameters during its execution. The special parameter ## is + updated to reflect the change. Special parameter 0 is unchanged. The + first element of the FFUUNNCCNNAAMMEE variable is set to the name of the func- + tion while the function is executing. + + All other aspects of the shell execution environment are identical + between a function and its caller with these exceptions: the DDEEBBUUGG and + RREETTUURRNN traps (see the description of the ttrraapp builtin under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below) are not inherited unless the function has been + given the ttrraaccee attribute (see the description of the ddeeccllaarree builtin + below) or the --oo ffuunnccttrraaccee shell option has been enabled with the sseett + builtin (in which case all functions inherit the DDEEBBUUGG and RREETTUURRNN + traps), and the EERRRR trap is not inherited unless the --oo eerrrrttrraaccee shell + option has been enabled. + + Variables local to the function may be declared with the llooccaall builtin + command. Ordinarily, variables and their values are shared between the + function and its caller. + + If the builtin command rreettuurrnn is executed in a function, the function + completes and execution resumes with the next command after the func- + tion call. Any command associated with the RREETTUURRNN trap is executed + before execution resumes. When a function completes, the values of the + positional parameters and the special parameter ## are restored to the + values they had prior to the function's execution. + + Function names and definitions may be listed with the --ff option to the + ddeeccllaarree or ttyyppeesseett builtin commands. The --FF option to ddeeccllaarree or ttyyppee-- + sseett will list the function names only (and optionally the source file + and line number, if the eexxttddeebbuugg shell option is enabled). Functions + may be exported so that subshells automatically have them defined with + the --ff option to the eexxppoorrtt builtin. A function definition may be + deleted using the --ff option to the uunnsseett builtin. Note that shell + functions and variables with the same name may result in multiple iden- + tically-named entries in the environment passed to the shell's chil- + dren. Care should be taken in cases where this may cause a problem. + + Functions may be recursive. No limit is imposed on the number of + recursive calls. + +AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN + The shell allows arithmetic expressions to be evaluated, under certain + circumstances (see the lleett and ddeeccllaarree builtin commands and AArriitthhmmeettiicc + EExxppaannssiioonn). Evaluation is done in fixed-width integers with no check + for overflow, though division by 0 is trapped and flagged as an error. + The operators and their precedence, associativity, and values are the + same as in the C language. The following list of operators is grouped + into levels of equal-precedence operators. The levels are listed in + order of decreasing precedence. + + _i_d++++ _i_d---- + variable post-increment and post-decrement + ++++_i_d ----_i_d + variable pre-increment and pre-decrement + -- ++ unary minus and plus + !! ~~ logical and bitwise negation + **** exponentiation + ** // %% multiplication, division, remainder + ++ -- addition, subtraction + <<<< >>>> left and right bitwise shifts + <<== >>== << >> + comparison + ==== !!== equality and inequality + && bitwise AND + ^^ bitwise exclusive OR + || bitwise OR + &&&& logical AND + |||| logical OR + _e_x_p_r??_e_x_p_r::_e_x_p_r + conditional operator + == **== //== %%== ++== --== <<<<== >>>>== &&== ^^== ||== + assignment + _e_x_p_r_1 ,, _e_x_p_r_2 + comma + + Shell variables are allowed as operands; parameter expansion is per- + formed before the expression is evaluated. Within an expression, shell + variables may also be referenced by name without using the parameter + expansion syntax. A shell variable that is null or unset evaluates to + 0 when referenced by name without using the parameter expansion syntax. + The value of a variable is evaluated as an arithmetic expression when + it is referenced, or when a variable which has been given the _i_n_t_e_g_e_r + attribute using ddeeccllaarree --ii is assigned a value. A null value evaluates + to 0. A shell variable need not have its integer attribute turned on + to be used in an expression. + + Constants with a leading 0 are interpreted as octal numbers. A leading + 0x or 0X denotes hexadecimal. Otherwise, numbers take the form + [_b_a_s_e_#]n, where _b_a_s_e is a decimal number between 2 and 64 representing + the arithmetic base, and _n is a number in that base. If _b_a_s_e_# is omit- + ted, then base 10 is used. The digits greater than 9 are represented + by the lowercase letters, the uppercase letters, @, and _, in that + order. If _b_a_s_e is less than or equal to 36, lowercase and uppercase + letters may be used interchangeably to represent numbers between 10 and + 35. + + Operators are evaluated in order of precedence. Sub-expressions in + parentheses are evaluated first and may override the precedence rules + above. + +CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS + Conditional expressions are used by the [[[[ compound command and the + tteesstt and [[ builtin commands to test file attributes and perform string + and arithmetic comparisons. Expressions are formed from the following + unary or binary primaries. If any _f_i_l_e argument to one of the pri- + maries is of the form _/_d_e_v_/_f_d_/_n, then file descriptor _n is checked. If + the _f_i_l_e argument to one of the primaries is one of _/_d_e_v_/_s_t_d_i_n, + _/_d_e_v_/_s_t_d_o_u_t, or _/_d_e_v_/_s_t_d_e_r_r, file descriptor 0, 1, or 2, respectively, + is checked. + + Unless otherwise specified, primaries that operate on files follow sym- + bolic links and operate on the target of the link, rather than the link + itself. + + When used with [[[[, The << and >> operators sort lexicographically using + the current locale. + + --aa _f_i_l_e + True if _f_i_l_e exists. + --bb _f_i_l_e + True if _f_i_l_e exists and is a block special file. + --cc _f_i_l_e + True if _f_i_l_e exists and is a character special file. + --dd _f_i_l_e + True if _f_i_l_e exists and is a directory. + --ee _f_i_l_e + True if _f_i_l_e exists. + --ff _f_i_l_e + True if _f_i_l_e exists and is a regular file. + --gg _f_i_l_e + True if _f_i_l_e exists and is set-group-id. + --hh _f_i_l_e + True if _f_i_l_e exists and is a symbolic link. + --kk _f_i_l_e + True if _f_i_l_e exists and its ``sticky'' bit is set. + --pp _f_i_l_e + True if _f_i_l_e exists and is a named pipe (FIFO). + --rr _f_i_l_e + True if _f_i_l_e exists and is readable. + --ss _f_i_l_e + True if _f_i_l_e exists and has a size greater than zero. + --tt _f_d True if file descriptor _f_d is open and refers to a terminal. + --uu _f_i_l_e + True if _f_i_l_e exists and its set-user-id bit is set. + --ww _f_i_l_e + True if _f_i_l_e exists and is writable. + --xx _f_i_l_e + True if _f_i_l_e exists and is executable. + --OO _f_i_l_e + True if _f_i_l_e exists and is owned by the effective user id. + --GG _f_i_l_e + True if _f_i_l_e exists and is owned by the effective group id. + --LL _f_i_l_e + True if _f_i_l_e exists and is a symbolic link. + --SS _f_i_l_e + True if _f_i_l_e exists and is a socket. + --NN _f_i_l_e + True if _f_i_l_e exists and has been modified since it was last + read. + _f_i_l_e_1 -nntt _f_i_l_e_2 + True if _f_i_l_e_1 is newer (according to modification date) than + _f_i_l_e_2, or if _f_i_l_e_1 exists and _f_i_l_e_2 does not. + _f_i_l_e_1 -oott _f_i_l_e_2 + True if _f_i_l_e_1 is older than _f_i_l_e_2, or if _f_i_l_e_2 exists and _f_i_l_e_1 + does not. + _f_i_l_e_1 --eeff _f_i_l_e_2 + True if _f_i_l_e_1 and _f_i_l_e_2 refer to the same device and inode num- + bers. + --oo _o_p_t_n_a_m_e + True if shell option _o_p_t_n_a_m_e is enabled. See the list of + options under the description of the --oo option to the sseett + builtin below. + --zz _s_t_r_i_n_g + True if the length of _s_t_r_i_n_g is zero. + _s_t_r_i_n_g + --nn _s_t_r_i_n_g + True if the length of _s_t_r_i_n_g is non-zero. + + _s_t_r_i_n_g_1 ==== _s_t_r_i_n_g_2 + _s_t_r_i_n_g_1 == _s_t_r_i_n_g_2 + True if the strings are equal. == should be used with the tteesstt + command for POSIX conformance. + + _s_t_r_i_n_g_1 !!== _s_t_r_i_n_g_2 + True if the strings are not equal. + + _s_t_r_i_n_g_1 << _s_t_r_i_n_g_2 + True if _s_t_r_i_n_g_1 sorts before _s_t_r_i_n_g_2 lexicographically. + + _s_t_r_i_n_g_1 >> _s_t_r_i_n_g_2 + True if _s_t_r_i_n_g_1 sorts after _s_t_r_i_n_g_2 lexicographically. + + _a_r_g_1 OOPP _a_r_g_2 + OOPP is one of --eeqq, --nnee, --lltt, --llee, --ggtt, or --ggee. These arithmetic + binary operators return true if _a_r_g_1 is equal to, not equal to, + less than, less than or equal to, greater than, or greater than + or equal to _a_r_g_2, respectively. _A_r_g_1 and _a_r_g_2 may be positive + or negative integers. + +SSIIMMPPLLEE CCOOMMMMAANNDD EEXXPPAANNSSIIOONN + When a simple command is executed, the shell performs the following + expansions, assignments, and redirections, from left to right. + + 1. The words that the parser has marked as variable assignments + (those preceding the command name) and redirections are saved + for later processing. + + 2. The words that are not variable assignments or redirections are + expanded. If any words remain after expansion, the first word + is taken to be the name of the command and the remaining words + are the arguments. + + 3. Redirections are performed as described above under RREEDDIIRREECCTTIIOONN. + + 4. The text after the == in each variable assignment undergoes tilde + expansion, parameter expansion, command substitution, arithmetic + expansion, and quote removal before being assigned to the vari- + able. + + If no command name results, the variable assignments affect the current + shell environment. Otherwise, the variables are added to the environ- + ment of the executed command and do not affect the current shell envi- + ronment. If any of the assignments attempts to assign a value to a + readonly variable, an error occurs, and the command exits with a non- + zero status. + + If no command name results, redirections are performed, but do not + affect the current shell environment. A redirection error causes the + command to exit with a non-zero status. + + If there is a command name left after expansion, execution proceeds as + described below. Otherwise, the command exits. If one of the expan- + sions contained a command substitution, the exit status of the command + is the exit status of the last command substitution performed. If + there were no command substitutions, the command exits with a status of + zero. + +CCOOMMMMAANNDD EEXXEECCUUTTIIOONN + After a command has been split into words, if it results in a simple + command and an optional list of arguments, the following actions are + taken. + + If the command name contains no slashes, the shell attempts to locate + it. If there exists a shell function by that name, that function is + invoked as described above in FFUUNNCCTTIIOONNSS. If the name does not match a + function, the shell searches for it in the list of shell builtins. If + a match is found, that builtin is invoked. + + If the name is neither a shell function nor a builtin, and contains no + slashes, bbaasshh searches each element of the PPAATTHH for a directory con- + taining an executable file by that name. BBaasshh uses a hash table to + remember the full pathnames of executable files (see hhaasshh under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS below). A full search of the directories in PPAATTHH is + performed only if the command is not found in the hash table. If the + search is unsuccessful, the shell searches for a defined shell function + named ccoommmmaanndd__nnoott__ffoouunndd__hhaannddllee. If that function exists, it is invoked + with the original command and the original command's arguments as its + arguments, and the function's exit status becomes the exit status of + the shell. If that function is not defined, the shell prints an error + message and returns an exit status of 127. + + If the search is successful, or if the command name contains one or + more slashes, the shell executes the named program in a separate execu- + tion environment. Argument 0 is set to the name given, and the remain- + ing arguments to the command are set to the arguments given, if any. + + If this execution fails because the file is not in executable format, + and the file is not a directory, it is assumed to be a _s_h_e_l_l _s_c_r_i_p_t, a + file containing shell commands. A subshell is spawned to execute it. + This subshell reinitializes itself, so that the effect is as if a new + shell had been invoked to handle the script, with the exception that + the locations of commands remembered by the parent (see hhaasshh below + under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS) are retained by the child. + + If the program is a file beginning with ##!!, the remainder of the first + line specifies an interpreter for the program. The shell executes the + specified interpreter on operating systems that do not handle this exe- + cutable format themselves. The arguments to the interpreter consist of + a single optional argument following the interpreter name on the first + line of the program, followed by the name of the program, followed by + the command arguments, if any. + +CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT + The shell has an _e_x_e_c_u_t_i_o_n _e_n_v_i_r_o_n_m_e_n_t, which consists of the follow- + ing: + + + +o open files inherited by the shell at invocation, as modified by + redirections supplied to the eexxeecc builtin + + +o the current working directory as set by ccdd, ppuusshhdd, or ppooppdd, or + inherited by the shell at invocation + + +o the file creation mode mask as set by uummaasskk or inherited from + the shell's parent + + +o current traps set by ttrraapp + + +o shell parameters that are set by variable assignment or with sseett + or inherited from the shell's parent in the environment + + +o shell functions defined during execution or inherited from the + shell's parent in the environment + + +o options enabled at invocation (either by default or with com- + mand-line arguments) or by sseett + + +o options enabled by sshhoopptt + + +o shell aliases defined with aalliiaass + + +o various process IDs, including those of background jobs, the + value of $$$$, and the value of PPPPIIDD + + When a simple command other than a builtin or shell function is to be + executed, it is invoked in a separate execution environment that con- + sists of the following. Unless otherwise noted, the values are inher- + ited from the shell. + + + +o the shell's open files, plus any modifications and additions + specified by redirections to the command + + +o the current working directory + + +o the file creation mode mask + + +o shell variables and functions marked for export, along with + variables exported for the command, passed in the environment + + +o traps caught by the shell are reset to the values inherited from + the shell's parent, and traps ignored by the shell are ignored + + A command invoked in this separate environment cannot affect the + shell's execution environment. + + Command substitution, commands grouped with parentheses, and asynchro- + nous commands are invoked in a subshell environment that is a duplicate + of the shell environment, except that traps caught by the shell are + reset to the values that the shell inherited from its parent at invoca- + tion. Builtin commands that are invoked as part of a pipeline are also + executed in a subshell environment. Changes made to the subshell envi- + ronment cannot affect the shell's execution environment. + + Subshells spawned to execute command substitutions inherit the value of + the --ee option from the parent shell. When not in posix mode, Bash + clears the --ee option in such subshells. + + If a command is followed by a && and job control is not active, the + default standard input for the command is the empty file _/_d_e_v_/_n_u_l_l. + Otherwise, the invoked command inherits the file descriptors of the + calling shell as modified by redirections. + +EENNVVIIRROONNMMEENNTT + When a program is invoked it is given an array of strings called the + _e_n_v_i_r_o_n_m_e_n_t. This is a list of _n_a_m_e-_v_a_l_u_e pairs, of the form + _n_a_m_e=_v_a_l_u_e. + + The shell provides several ways to manipulate the environment. On + invocation, the shell scans its own environment and creates a parameter + for each name found, automatically marking it for _e_x_p_o_r_t to child pro- + cesses. Executed commands inherit the environment. The eexxppoorrtt and + ddeeccllaarree --xx commands allow parameters and functions to be added to and + deleted from the environment. If the value of a parameter in the envi- + ronment is modified, the new value becomes part of the environment, + replacing the old. The environment inherited by any executed command + consists of the shell's initial environment, whose values may be modi- + fied in the shell, less any pairs removed by the uunnsseett command, plus + any additions via the eexxppoorrtt and ddeeccllaarree --xx commands. + + The environment for any _s_i_m_p_l_e _c_o_m_m_a_n_d or function may be augmented + temporarily by prefixing it with parameter assignments, as described + above in PPAARRAAMMEETTEERRSS. These assignment statements affect only the envi- + ronment seen by that command. + + If the --kk option is set (see the sseett builtin command below), then _a_l_l + parameter assignments are placed in the environment for a command, not + just those that precede the command name. + + When bbaasshh invokes an external command, the variable __ is set to the + full file name of the command and passed to that command in its envi- + ronment. + +EEXXIITT SSTTAATTUUSS + The exit status of an executed command is the value returned by the + _w_a_i_t_p_i_d system call or equivalent function. Exit statuses fall between + 0 and 255, though, as explained below, the shell may use values above + 125 specially. Exit statuses from shell builtins and compound commands + are also limited to this range. Under certain circumstances, the shell + will use special values to indicate specific failure modes. + + For the shell's purposes, a command which exits with a zero exit status + has succeeded. An exit status of zero indicates success. A non-zero + exit status indicates failure. When a command terminates on a fatal + signal _N, bbaasshh uses the value of 128+_N as the exit status. + + If a command is not found, the child process created to execute it + returns a status of 127. If a command is found but is not executable, + the return status is 126. + + If a command fails because of an error during expansion or redirection, + the exit status is greater than zero. + + Shell builtin commands return a status of 0 (_t_r_u_e) if successful, and + non-zero (_f_a_l_s_e) if an error occurs while they execute. All builtins + return an exit status of 2 to indicate incorrect usage. + + BBaasshh itself returns the exit status of the last command executed, + unless a syntax error occurs, in which case it exits with a non-zero + value. See also the eexxiitt builtin command below. + +SSIIGGNNAALLSS + When bbaasshh is interactive, in the absence of any traps, it ignores + SSIIGGTTEERRMM (so that kkiillll 00 does not kill an interactive shell), and SSIIGGIINNTT + is caught and handled (so that the wwaaiitt builtin is interruptible). In + all cases, bbaasshh ignores SSIIGGQQUUIITT. If job control is in effect, bbaasshh + ignores SSIIGGTTTTIINN, SSIIGGTTTTOOUU, and SSIIGGTTSSTTPP. + + Non-builtin commands run by bbaasshh have signal handlers set to the values + inherited by the shell from its parent. When job control is not in + effect, asynchronous commands ignore SSIIGGIINNTT and SSIIGGQQUUIITT in addition to + these inherited handlers. Commands run as a result of command substi- + tution ignore the keyboard-generated job control signals SSIIGGTTTTIINN, SSIIGGTT-- + TTOOUU, and SSIIGGTTSSTTPP. + + The shell exits by default upon receipt of a SSIIGGHHUUPP. Before exiting, + an interactive shell resends the SSIIGGHHUUPP to all jobs, running or + stopped. Stopped jobs are sent SSIIGGCCOONNTT to ensure that they receive the + SSIIGGHHUUPP. To prevent the shell from sending the signal to a particular + job, it should be removed from the jobs table with the ddiissoowwnn builtin + (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) or marked to not receive SSIIGGHHUUPP + using ddiissoowwnn --hh. + + If the hhuuppoonneexxiitt shell option has been set with sshhoopptt, bbaasshh sends a + SSIIGGHHUUPP to all jobs when an interactive login shell exits. + + If bbaasshh is waiting for a command to complete and receives a signal for + which a trap has been set, the trap will not be executed until the com- + mand completes. When bbaasshh is waiting for an asynchronous command via + the wwaaiitt builtin, the reception of a signal for which a trap has been + set will cause the wwaaiitt builtin to return immediately with an exit sta- + tus greater than 128, immediately after which the trap is executed. + +JJOOBB CCOONNTTRROOLL + _J_o_b _c_o_n_t_r_o_l refers to the ability to selectively stop (_s_u_s_p_e_n_d) the + execution of processes and continue (_r_e_s_u_m_e) their execution at a later + point. A user typically employs this facility via an interactive + interface supplied jointly by the operating system kernel's terminal + driver and bbaasshh. + + The shell associates a _j_o_b with each pipeline. It keeps a table of + currently executing jobs, which may be listed with the jjoobbss command. + When bbaasshh starts a job asynchronously (in the _b_a_c_k_g_r_o_u_n_d), it prints a + line that looks like: + + [1] 25647 + + indicating that this job is job number 1 and that the process ID of the + last process in the pipeline associated with this job is 25647. All of + the processes in a single pipeline are members of the same job. BBaasshh + uses the _j_o_b abstraction as the basis for job control. + + To facilitate the implementation of the user interface to job control, + the operating system maintains the notion of a _c_u_r_r_e_n_t _t_e_r_m_i_n_a_l _p_r_o_c_e_s_s + _g_r_o_u_p _I_D. Members of this process group (processes whose process group + ID is equal to the current terminal process group ID) receive keyboard- + generated signals such as SSIIGGIINNTT. These processes are said to be in + the _f_o_r_e_g_r_o_u_n_d. _B_a_c_k_g_r_o_u_n_d processes are those whose process group ID + differs from the terminal's; such processes are immune to keyboard-gen- + erated signals. Only foreground processes are allowed to read from or, + if the user so specifies with stty tostop, write to the terminal. + Background processes which attempt to read from (write to when stty + tostop is in effect) the terminal are sent a SSIIGGTTTTIINN ((SSIIGGTTTTOOUU)) signal + by the kernel's terminal driver, which, unless caught, suspends the + process. + + If the operating system on which bbaasshh is running supports job control, + bbaasshh contains facilities to use it. Typing the _s_u_s_p_e_n_d character (typ- + ically ^^ZZ, Control-Z) while a process is running causes that process to + be stopped and returns control to bbaasshh. Typing the _d_e_l_a_y_e_d _s_u_s_p_e_n_d + character (typically ^^YY, Control-Y) causes the process to be stopped + when it attempts to read input from the terminal, and control to be + returned to bbaasshh. The user may then manipulate the state of this job, + using the bbgg command to continue it in the background, the ffgg command + to continue it in the foreground, or the kkiillll command to kill it. A ^^ZZ + takes effect immediately, and has the additional side effect of causing + pending output and typeahead to be discarded. + + There are a number of ways to refer to a job in the shell. The charac- + ter %% introduces a job specification (_j_o_b_s_p_e_c). Job number _n may be + referred to as %%nn. A job may also be referred to using a prefix of the + name used to start it, or using a substring that appears in its command + line. For example, %%ccee refers to a stopped ccee job. If a prefix + matches more than one job, bbaasshh reports an error. Using %%??ccee, on the + other hand, refers to any job containing the string ccee in its command + line. If the substring matches more than one job, bbaasshh reports an + error. The symbols %%%% and %%++ refer to the shell's notion of the _c_u_r_- + _r_e_n_t _j_o_b, which is the last job stopped while it was in the foreground + or started in the background. The _p_r_e_v_i_o_u_s _j_o_b may be referenced using + %%--. If there is only a single job, %%++ and %%-- can both be used to refer + to that job. In output pertaining to jobs (e.g., the output of the + jjoobbss command), the current job is always flagged with a ++, and the pre- + vious job with a --. A single % (with no accompanying job specifica- + tion) also refers to the current job. + + Simply naming a job can be used to bring it into the foreground: %%11 is + a synonym for ````ffgg %%11'''', bringing job 1 from the background into the + foreground. Similarly, ````%%11 &&'''' resumes job 1 in the background, + equivalent to ````bbgg %%11''''. + + The shell learns immediately whenever a job changes state. Normally, + bbaasshh waits until it is about to print a prompt before reporting changes + in a job's status so as to not interrupt any other output. If the --bb + option to the sseett builtin command is enabled, bbaasshh reports such changes + immediately. Any trap on SSIIGGCCHHLLDD is executed for each child that + exits. + + If an attempt to exit bbaasshh is made while jobs are stopped (or, if the + cchheecckkjjoobbss shell option has been enabled using the sshhoopptt builtin, run- + ning), the shell prints a warning message, and, if the cchheecckkjjoobbss option + is enabled, lists the jobs and their statuses. The jjoobbss command may + then be used to inspect their status. If a second attempt to exit is + made without an intervening command, the shell does not print another + warning, and any stopped jobs are terminated. + +PPRROOMMPPTTIINNGG + When executing interactively, bbaasshh displays the primary prompt PPSS11 when + it is ready to read a command, and the secondary prompt PPSS22 when it + needs more input to complete a command. BBaasshh allows these prompt + strings to be customized by inserting a number of backslash-escaped + special characters that are decoded as follows: + \\aa an ASCII bell character (07) + \\dd the date in "Weekday Month Date" format (e.g., "Tue May + 26") + \\DD{{_f_o_r_m_a_t}} + the _f_o_r_m_a_t is passed to _s_t_r_f_t_i_m_e(3) and the result is + inserted into the prompt string; an empty _f_o_r_m_a_t results + in a locale-specific time representation. The braces are + required + \\ee an ASCII escape character (033) + \\hh the hostname up to the first `.' + \\HH the hostname + \\jj the number of jobs currently managed by the shell + \\ll the basename of the shell's terminal device name + \\nn newline + \\rr carriage return + \\ss the name of the shell, the basename of $$00 (the portion + following the final slash) + \\tt the current time in 24-hour HH:MM:SS format + \\TT the current time in 12-hour HH:MM:SS format + \\@@ the current time in 12-hour am/pm format + \\AA the current time in 24-hour HH:MM format + \\uu the username of the current user + \\vv the version of bbaasshh (e.g., 2.00) + \\VV the release of bbaasshh, version + patch level (e.g., 2.00.0) + \\ww the current working directory, with $$HHOOMMEE abbreviated + with a tilde (uses the value of the PPRROOMMPPTT__DDIIRRTTRRIIMM vari- + able) + \\WW the basename of the current working directory, with $$HHOOMMEE + abbreviated with a tilde + \\!! the history number of this command + \\## the command number of this command + \\$$ if the effective UID is 0, a ##, otherwise a $$ + \\_n_n_n the character corresponding to the octal number _n_n_n + \\\\ a backslash + \\[[ begin a sequence of non-printing characters, which could + be used to embed a terminal control sequence into the + prompt + \\]] end a sequence of non-printing characters + + The command number and the history number are usually different: the + history number of a command is its position in the history list, which + may include commands restored from the history file (see HHIISSTTOORRYY + below), while the command number is the position in the sequence of + commands executed during the current shell session. After the string + is decoded, it is expanded via parameter expansion, command substitu- + tion, arithmetic expansion, and quote removal, subject to the value of + the pprroommppttvvaarrss shell option (see the description of the sshhoopptt command + under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + +RREEAADDLLIINNEE + This is the library that handles reading input when using an interac- + tive shell, unless the ----nnooeeddiittiinngg option is given at shell invocation. + Line editing is also used when using the --ee option to the rreeaadd builtin. + By default, the line editing commands are similar to those of emacs. A + vi-style line editing interface is also available. Line editing can be + enabled at any time using the --oo eemmaaccss or --oo vvii options to the sseett + builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). To turn off line editing + after the shell is running, use the ++oo eemmaaccss or ++oo vvii options to the + sseett builtin. + + RReeaaddlliinnee NNoottaattiioonn + In this section, the emacs-style notation is used to denote keystrokes. + Control keys are denoted by C-_k_e_y, e.g., C-n means Control-N. Simi- + larly, _m_e_t_a keys are denoted by M-_k_e_y, so M-x means Meta-X. (On key- + boards without a _m_e_t_a key, M-_x means ESC _x, i.e., press the Escape key + then the _x key. This makes ESC the _m_e_t_a _p_r_e_f_i_x. The combination M-C-_x + means ESC-Control-_x, or press the Escape key then hold the Control key + while pressing the _x key.) + + Readline commands may be given numeric _a_r_g_u_m_e_n_t_s, which normally act as + a repeat count. Sometimes, however, it is the sign of the argument + that is significant. Passing a negative argument to a command that + acts in the forward direction (e.g., kkiillll--lliinnee) causes that command to + act in a backward direction. Commands whose behavior with arguments + deviates from this are noted below. + + When a command is described as _k_i_l_l_i_n_g text, the text deleted is saved + for possible future retrieval (_y_a_n_k_i_n_g). The killed text is saved in a + _k_i_l_l _r_i_n_g. Consecutive kills cause the text to be accumulated into one + unit, which can be yanked all at once. Commands which do not kill text + separate the chunks of text on the kill ring. + + RReeaaddlliinnee IInniittiiaalliizzaattiioonn + Readline is customized by putting commands in an initialization file + (the _i_n_p_u_t_r_c file). The name of this file is taken from the value of + the IINNPPUUTTRRCC variable. If that variable is unset, the default is + _~_/_._i_n_p_u_t_r_c. When a program which uses the readline library starts up, + the initialization file is read, and the key bindings and variables are + set. There are only a few basic constructs allowed in the readline + initialization file. Blank lines are ignored. Lines beginning with a + ## are comments. Lines beginning with a $$ indicate conditional con- + structs. Other lines denote key bindings and variable settings. + + The default key-bindings may be changed with an _i_n_p_u_t_r_c file. Other + programs that use this library may add their own commands and bindings. + + For example, placing + + M-Control-u: universal-argument + or + C-Meta-u: universal-argument + into the _i_n_p_u_t_r_c would make M-C-u execute the readline command _u_n_i_v_e_r_- + _s_a_l_-_a_r_g_u_m_e_n_t. + + The following symbolic character names are recognized: _R_U_B_O_U_T, _D_E_L, + _E_S_C, _L_F_D, _N_E_W_L_I_N_E, _R_E_T, _R_E_T_U_R_N, _S_P_C, _S_P_A_C_E, and _T_A_B. + + In addition to command names, readline allows keys to be bound to a + string that is inserted when the key is pressed (a _m_a_c_r_o). + + RReeaaddlliinnee KKeeyy BBiinnddiinnggss + The syntax for controlling key bindings in the _i_n_p_u_t_r_c file is simple. + All that is required is the name of the command or the text of a macro + and a key sequence to which it should be bound. The name may be speci- + fied in one of two ways: as a symbolic key name, possibly with _M_e_t_a_- or + _C_o_n_t_r_o_l_- prefixes, or as a key sequence. + + When using the form kkeeyynnaammee:_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, _k_e_y_n_a_m_e is the name + of a key spelled out in English. For example: + + Control-u: universal-argument + Meta-Rubout: backward-kill-word + Control-o: "> output" + + In the above example, _C_-_u is bound to the function uunniivveerrssaall--aarrgguummeenntt, + _M_-_D_E_L is bound to the function bbaacckkwwaarrdd--kkiillll--wwoorrdd, and _C_-_o is bound to + run the macro expressed on the right hand side (that is, to insert the + text ``> output'' into the line). + + In the second form, ""kkeeyysseeqq"":_f_u_n_c_t_i_o_n_-_n_a_m_e or _m_a_c_r_o, kkeeyysseeqq differs + from kkeeyynnaammee above in that strings denoting an entire key sequence may + be specified by placing the sequence within double quotes. Some GNU + Emacs style key escapes can be used, as in the following example, but + the symbolic character names are not recognized. + + "\C-u": universal-argument + "\C-x\C-r": re-read-init-file + "\e[11~": "Function Key 1" + + In this example, _C_-_u is again bound to the function uunniivveerrssaall--aarrgguummeenntt. + _C_-_x _C_-_r is bound to the function rree--rreeaadd--iinniitt--ffiillee, and _E_S_C _[ _1 _1 _~ is + bound to insert the text ``Function Key 1''. + + The full set of GNU Emacs style escape sequences is + \\CC-- control prefix + \\MM-- meta prefix + \\ee an escape character + \\\\ backslash + \\"" literal " + \\'' literal ' + + In addition to the GNU Emacs style escape sequences, a second set of + backslash escapes is available: + \\aa alert (bell) + \\bb backspace + \\dd delete + \\ff form feed + \\nn newline + \\rr carriage return + \\tt horizontal tab + \\vv vertical tab + \\_n_n_n the eight-bit character whose value is the octal value + _n_n_n (one to three digits) + \\xx_H_H the eight-bit character whose value is the hexadecimal + value _H_H (one or two hex digits) + + When entering the text of a macro, single or double quotes must be used + to indicate a macro definition. Unquoted text is assumed to be a func- + tion name. In the macro body, the backslash escapes described above + are expanded. Backslash will quote any other character in the macro + text, including " and '. + + BBaasshh allows the current readline key bindings to be displayed or modi- + fied with the bbiinndd builtin command. The editing mode may be switched + during interactive use by using the --oo option to the sseett builtin com- + mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). + + RReeaaddlliinnee VVaarriiaabblleess + Readline has variables that can be used to further customize its behav- + ior. A variable may be set in the _i_n_p_u_t_r_c file with a statement of the + form + + sseett _v_a_r_i_a_b_l_e_-_n_a_m_e _v_a_l_u_e + + Except where noted, readline variables can take the values OOnn or OOffff + (without regard to case). Unrecognized variable names are ignored. + When a variable value is read, empty or null values, "on" (case-insen- + sitive), and "1" are equivalent to OOnn. All other values are equivalent + to OOffff. The variables and their default values are: + + bbeellll--ssttyyllee ((aauuddiibbllee)) + Controls what happens when readline wants to ring the terminal + bell. If set to nnoonnee, readline never rings the bell. If set to + vviissiibbllee, readline uses a visible bell if one is available. If + set to aauuddiibbllee, readline attempts to ring the terminal's bell. + bbiinndd--ttttyy--ssppeecciiaall--cchhaarrss ((OOnn)) + If set to OOnn, readline attempts to bind the control characters + treated specially by the kernel's terminal driver to their read- + line equivalents. + ccoommmmeenntt--bbeeggiinn ((````##'''')) + The string that is inserted when the readline iinnsseerrtt--ccoommmmeenntt + command is executed. This command is bound to MM--## in emacs mode + and to ## in vi command mode. + ccoommpplleettiioonn--iiggnnoorree--ccaassee ((OOffff)) + If set to OOnn, readline performs filename matching and completion + in a case-insensitive fashion. + ccoommpplleettiioonn--pprreeffiixx--ddiissppllaayy--lleennggtthh ((00)) + The length in characters of the common prefix of a list of pos- + sible completions that is displayed without modification. When + set to a value greater than zero, common prefixes longer than + this value are replaced with an ellipsis when displaying possi- + ble completions. + ccoommpplleettiioonn--qquueerryy--iitteemmss ((110000)) + This determines when the user is queried about viewing the num- + ber of possible completions generated by the ppoossssiibbllee--ccoommppllee-- + ttiioonnss command. It may be set to any integer value greater than + or equal to zero. If the number of possible completions is + greater than or equal to the value of this variable, the user is + asked whether or not he wishes to view them; otherwise they are + simply listed on the terminal. + ccoonnvveerrtt--mmeettaa ((OOnn)) + If set to OOnn, readline will convert characters with the eighth + bit set to an ASCII key sequence by stripping the eighth bit and + prefixing an escape character (in effect, using escape as the + _m_e_t_a _p_r_e_f_i_x). + ddiissaabbllee--ccoommpplleettiioonn ((OOffff)) + If set to OOnn, readline will inhibit word completion. Completion + characters will be inserted into the line as if they had been + mapped to sseellff--iinnsseerrtt. + eeddiittiinngg--mmooddee ((eemmaaccss)) + Controls whether readline begins with a set of key bindings sim- + ilar to _e_m_a_c_s or _v_i. eeddiittiinngg--mmooddee can be set to either eemmaaccss or + vvii. + eecchhoo--ccoonnttrrooll--cchhaarraacctteerrss ((OOnn)) + When set to OOnn, on operating systems that indicate they support + it, readline echoes a character corresponding to a signal gener- + ated from the keyboard. + eennaabbllee--kkeeyyppaadd ((OOffff)) + When set to OOnn, readline will try to enable the application key- + pad when it is called. Some systems need this to enable the + arrow keys. + eennaabbllee--mmeettaa--kkeeyy ((OOnn)) + When set to OOnn, readline will try to enable any meta modifier + key the terminal claims to support when it is called. On many + terminals, the meta key is used to send eight-bit characters. + eexxppaanndd--ttiillddee ((OOffff)) + If set to oonn, tilde expansion is performed when readline + attempts word completion. + hhiissttoorryy--pprreesseerrvvee--ppooiinntt ((OOffff)) + If set to oonn, the history code attempts to place point at the + same location on each history line retrieved with pprreevviioouuss--hhiiss-- + ttoorryy or nneexxtt--hhiissttoorryy. + hhiissttoorryy--ssiizzee ((00)) + Set the maximum number of history entries saved in the history + list. If set to zero, the number of entries in the history list + is not limited. + hhoorriizzoonnttaall--ssccrroollll--mmooddee ((OOffff)) + When set to OOnn, makes readline use a single line for display, + scrolling the input horizontally on a single screen line when it + becomes longer than the screen width rather than wrapping to a + new line. + iinnppuutt--mmeettaa ((OOffff)) + If set to OOnn, readline will enable eight-bit input (that is, it + will not strip the high bit from the characters it reads), + regardless of what the terminal claims it can support. The name + mmeettaa--ffllaagg is a synonym for this variable. + iisseeaarrcchh--tteerrmmiinnaattoorrss ((````CC--[[CC--JJ'''')) + The string of characters that should terminate an incremental + search without subsequently executing the character as a com- + mand. If this variable has not been given a value, the charac- + ters _E_S_C and _C_-_J will terminate an incremental search. + kkeeyymmaapp ((eemmaaccss)) + Set the current readline keymap. The set of valid keymap names + is _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_c_o_m_- + _m_a_n_d, and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is + equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d. The default value is _e_m_a_c_s; the + value of eeddiittiinngg--mmooddee also affects the default keymap. + mmaarrkk--ddiirreeccttoorriieess ((OOnn)) + If set to OOnn, completed directory names have a slash appended. + mmaarrkk--mmooddiiffiieedd--lliinneess ((OOffff)) + If set to OOnn, history lines that have been modified are dis- + played with a preceding asterisk (**). + mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess ((OOffff)) + If set to OOnn, completed names which are symbolic links to direc- + tories have a slash appended (subject to the value of + mmaarrkk--ddiirreeccttoorriieess). + mmaattcchh--hhiiddddeenn--ffiilleess ((OOnn)) + This variable, when set to OOnn, causes readline to match files + whose names begin with a `.' (hidden files) when performing + filename completion, unless the leading `.' is supplied by the + user in the filename to be completed. + oouuttppuutt--mmeettaa ((OOffff)) + If set to OOnn, readline will display characters with the eighth + bit set directly rather than as a meta-prefixed escape sequence. + ppaaggee--ccoommpplleettiioonnss ((OOnn)) + If set to OOnn, readline uses an internal _m_o_r_e-like pager to dis- + play a screenful of possible completions at a time. + pprriinntt--ccoommpplleettiioonnss--hhoorriizzoonnttaallllyy ((OOffff)) + If set to OOnn, readline will display completions with matches + sorted horizontally in alphabetical order, rather than down the + screen. + rreevveerrtt--aallll--aatt--nneewwlliinnee ((OOffff)) + If set to oonn, readline will undo all changes to history lines + before returning when aacccceepptt--lliinnee is executed. By default, his- + tory lines may be modified and retain individual undo lists + across calls to rreeaaddlliinnee. + sshhooww--aallll--iiff--aammbbiigguuoouuss ((OOffff)) + This alters the default behavior of the completion functions. + If set to oonn, words which have more than one possible completion + cause the matches to be listed immediately instead of ringing + the bell. + sshhooww--aallll--iiff--uunnmmooddiiffiieedd ((OOffff)) + This alters the default behavior of the completion functions in + a fashion similar to sshhooww--aallll--iiff--aammbbiigguuoouuss. If set to oonn, words + which have more than one possible completion without any possi- + ble partial completion (the possible completions don't share a + common prefix) cause the matches to be listed immediately + instead of ringing the bell. + sskkiipp--ccoommpplleetteedd--tteexxtt ((OOffff)) + If set to OOnn, this alters the default completion behavior when + inserting a single match into the line. It's only active when + performing completion in the middle of a word. If enabled, + readline does not insert characters from the completion that + match characters after point in the word being completed, so + portions of the word following the cursor are not duplicated. + vviissiibbllee--ssttaattss ((OOffff)) + If set to OOnn, a character denoting a file's type as reported by + _s_t_a_t(2) is appended to the filename when listing possible com- + pletions. + + RReeaaddlliinnee CCoonnddiittiioonnaall CCoonnssttrruuccttss + Readline implements a facility similar in spirit to the conditional + compilation features of the C preprocessor which allows key bindings + and variable settings to be performed as the result of tests. There + are four parser directives used. + + $$iiff The $$iiff construct allows bindings to be made based on the edit- + ing mode, the terminal being used, or the application using + readline. The text of the test extends to the end of the line; + no characters are required to isolate it. + + mmooddee The mmooddee== form of the $$iiff directive is used to test + whether readline is in emacs or vi mode. This may be + used in conjunction with the sseett kkeeyymmaapp command, for + instance, to set bindings in the _e_m_a_c_s_-_s_t_a_n_d_a_r_d and + _e_m_a_c_s_-_c_t_l_x keymaps only if readline is starting out in + emacs mode. + + tteerrmm The tteerrmm== form may be used to include terminal-specific + key bindings, perhaps to bind the key sequences output by + the terminal's function keys. The word on the right side + of the == is tested against the both full name of the ter- + minal and the portion of the terminal name before the + first --. This allows _s_u_n to match both _s_u_n and _s_u_n_-_c_m_d, + for instance. + + aapppplliiccaattiioonn + The aapppplliiccaattiioonn construct is used to include application- + specific settings. Each program using the readline + library sets the _a_p_p_l_i_c_a_t_i_o_n _n_a_m_e, and an initialization + file can test for a particular value. This could be used + to bind key sequences to functions useful for a specific + program. For instance, the following command adds a key + sequence that quotes the current or previous word in + Bash: + + $$iiff Bash + # Quote the current or previous word + "\C-xq": "\eb\"\ef\"" + $$eennddiiff + + $$eennddiiff This command, as seen in the previous example, terminates an $$iiff + command. + + $$eellssee Commands in this branch of the $$iiff directive are executed if the + test fails. + + $$iinncclluuddee + This directive takes a single filename as an argument and reads + commands and bindings from that file. For example, the follow- + ing directive would read _/_e_t_c_/_i_n_p_u_t_r_c: + + $$iinncclluuddee _/_e_t_c_/_i_n_p_u_t_r_c + + SSeeaarrcchhiinngg + Readline provides commands for searching through the command history + (see HHIISSTTOORRYY below) for lines containing a specified string. There are + two search modes: _i_n_c_r_e_m_e_n_t_a_l and _n_o_n_-_i_n_c_r_e_m_e_n_t_a_l. + + Incremental searches begin before the user has finished typing the + search string. As each character of the search string is typed, read- + line displays the next entry from the history matching the string typed + so far. An incremental search requires only as many characters as + needed to find the desired history entry. The characters present in + the value of the iisseeaarrcchh--tteerrmmiinnaattoorrss variable are used to terminate an + incremental search. If that variable has not been assigned a value the + Escape and Control-J characters will terminate an incremental search. + Control-G will abort an incremental search and restore the original + line. When the search is terminated, the history entry containing the + search string becomes the current line. + + To find other matching entries in the history list, type Control-S or + Control-R as appropriate. This will search backward or forward in the + history for the next entry matching the search string typed so far. + Any other key sequence bound to a readline command will terminate the + search and execute that command. For instance, a _n_e_w_l_i_n_e will termi- + nate the search and accept the line, thereby executing the command from + the history list. + + Readline remembers the last incremental search string. If two Control- + Rs are typed without any intervening characters defining a new search + string, any remembered search string is used. + + Non-incremental searches read the entire search string before starting + to search for matching history lines. The search string may be typed + by the user or be part of the contents of the current line. + + RReeaaddlliinnee CCoommmmaanndd NNaammeess + The following is a list of the names of the commands and the default + key sequences to which they are bound. Command names without an accom- + panying key sequence are unbound by default. In the following descrip- + tions, _p_o_i_n_t refers to the current cursor position, and _m_a_r_k refers to + a cursor position saved by the sseett--mmaarrkk command. The text between the + point and mark is referred to as the _r_e_g_i_o_n. + + CCoommmmaannddss ffoorr MMoovviinngg + bbeeggiinnnniinngg--ooff--lliinnee ((CC--aa)) + Move to the start of the current line. + eenndd--ooff--lliinnee ((CC--ee)) + Move to the end of the line. + ffoorrwwaarrdd--cchhaarr ((CC--ff)) + Move forward a character. + bbaacckkwwaarrdd--cchhaarr ((CC--bb)) + Move back a character. + ffoorrwwaarrdd--wwoorrdd ((MM--ff)) + Move forward to the end of the next word. Words are composed of + alphanumeric characters (letters and digits). + bbaacckkwwaarrdd--wwoorrdd ((MM--bb)) + Move back to the start of the current or previous word. Words + are composed of alphanumeric characters (letters and digits). + sshheellll--ffoorrwwaarrdd--wwoorrdd + Move forward to the end of the next word. Words are delimited + by non-quoted shell metacharacters. + sshheellll--bbaacckkwwaarrdd--wwoorrdd + Move back to the start of the current or previous word. Words + are delimited by non-quoted shell metacharacters. + cclleeaarr--ssccrreeeenn ((CC--ll)) + Clear the screen leaving the current line at the top of the + screen. With an argument, refresh the current line without + clearing the screen. + rreeddrraaww--ccuurrrreenntt--lliinnee + Refresh the current line. + + CCoommmmaannddss ffoorr MMaanniippuullaattiinngg tthhee HHiissttoorryy + aacccceepptt--lliinnee ((NNeewwlliinnee,, RReettuurrnn)) + Accept the line regardless of where the cursor is. If this line + is non-empty, add it to the history list according to the state + of the HHIISSTTCCOONNTTRROOLL variable. If the line is a modified history + line, then restore the history line to its original state. + pprreevviioouuss--hhiissttoorryy ((CC--pp)) + Fetch the previous command from the history list, moving back in + the list. + nneexxtt--hhiissttoorryy ((CC--nn)) + Fetch the next command from the history list, moving forward in + the list. + bbeeggiinnnniinngg--ooff--hhiissttoorryy ((MM--<<)) + Move to the first line in the history. + eenndd--ooff--hhiissttoorryy ((MM-->>)) + Move to the end of the input history, i.e., the line currently + being entered. + rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((CC--rr)) + Search backward starting at the current line and moving `up' + through the history as necessary. This is an incremental + search. + ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((CC--ss)) + Search forward starting at the current line and moving `down' + through the history as necessary. This is an incremental + search. + nnoonn--iinnccrreemmeennttaall--rreevveerrssee--sseeaarrcchh--hhiissttoorryy ((MM--pp)) + Search backward through the history starting at the current line + using a non-incremental search for a string supplied by the + user. + nnoonn--iinnccrreemmeennttaall--ffoorrwwaarrdd--sseeaarrcchh--hhiissttoorryy ((MM--nn)) + Search forward through the history using a non-incremental + search for a string supplied by the user. + hhiissttoorryy--sseeaarrcchh--ffoorrwwaarrdd + Search forward through the history for the string of characters + between the start of the current line and the point. This is a + non-incremental search. + hhiissttoorryy--sseeaarrcchh--bbaacckkwwaarrdd + Search backward through the history for the string of characters + between the start of the current line and the point. This is a + non-incremental search. + yyaannkk--nntthh--aarrgg ((MM--CC--yy)) + Insert the first argument to the previous command (usually the + second word on the previous line) at point. With an argument _n, + insert the _nth word from the previous command (the words in the + previous command begin with word 0). A negative argument + inserts the _nth word from the end of the previous command. Once + the argument _n is computed, the argument is extracted as if the + "!_n" history expansion had been specified. + yyaannkk--llaasstt--aarrgg ((MM--..,, MM--__)) + Insert the last argument to the previous command (the last word + of the previous history entry). With an argument, behave + exactly like yyaannkk--nntthh--aarrgg. Successive calls to yyaannkk--llaasstt--aarrgg + move back through the history list, inserting the last argument + of each line in turn. The history expansion facilities are used + to extract the last argument, as if the "!$" history expansion + had been specified. + sshheellll--eexxppaanndd--lliinnee ((MM--CC--ee)) + Expand the line as the shell does. This performs alias and his- + tory expansion as well as all of the shell word expansions. See + HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history expansion. + hhiissttoorryy--eexxppaanndd--lliinnee ((MM--^^)) + Perform history expansion on the current line. See HHIISSTTOORRYY + EEXXPPAANNSSIIOONN below for a description of history expansion. + mmaaggiicc--ssppaaccee + Perform history expansion on the current line and insert a + space. See HHIISSTTOORRYY EEXXPPAANNSSIIOONN below for a description of history + expansion. + aalliiaass--eexxppaanndd--lliinnee + Perform alias expansion on the current line. See AALLIIAASSEESS above + for a description of alias expansion. + hhiissttoorryy--aanndd--aalliiaass--eexxppaanndd--lliinnee + Perform history and alias expansion on the current line. + iinnsseerrtt--llaasstt--aarrgguummeenntt ((MM--..,, MM--__)) + A synonym for yyaannkk--llaasstt--aarrgg. + ooppeerraattee--aanndd--ggeett--nneexxtt ((CC--oo)) + Accept the current line for execution and fetch the next line + relative to the current line from the history for editing. Any + argument is ignored. + eeddiitt--aanndd--eexxeeccuuttee--ccoommmmaanndd ((CC--xxCC--ee)) + Invoke an editor on the current command line, and execute the + result as shell commands. BBaasshh attempts to invoke $$VVIISSUUAALL, + $$EEDDIITTOORR, and _e_m_a_c_s as the editor, in that order. + + CCoommmmaannddss ffoorr CChhaannggiinngg TTeexxtt + ddeelleettee--cchhaarr ((CC--dd)) + Delete the character at point. If point is at the beginning of + the line, there are no characters in the line, and the last + character typed was not bound to ddeelleettee--cchhaarr, then return EEOOFF. + bbaacckkwwaarrdd--ddeelleettee--cchhaarr ((RRuubboouutt)) + Delete the character behind the cursor. When given a numeric + argument, save the deleted text on the kill ring. + ffoorrwwaarrdd--bbaacckkwwaarrdd--ddeelleettee--cchhaarr + Delete the character under the cursor, unless the cursor is at + the end of the line, in which case the character behind the cur- + sor is deleted. + qquuootteedd--iinnsseerrtt ((CC--qq,, CC--vv)) + Add the next character typed to the line verbatim. This is how + to insert characters like CC--qq, for example. + ttaabb--iinnsseerrtt ((CC--vv TTAABB)) + Insert a tab character. + sseellff--iinnsseerrtt ((aa,, bb,, AA,, 11,, !!,, ......)) + Insert the character typed. + ttrraannssppoossee--cchhaarrss ((CC--tt)) + Drag the character before point forward over the character at + point, moving point forward as well. If point is at the end of + the line, then this transposes the two characters before point. + Negative arguments have no effect. + ttrraannssppoossee--wwoorrddss ((MM--tt)) + Drag the word before point past the word after point, moving + point over that word as well. If point is at the end of the + line, this transposes the last two words on the line. + uuppccaassee--wwoorrdd ((MM--uu)) + Uppercase the current (or following) word. With a negative + argument, uppercase the previous word, but do not move point. + ddoowwnnccaassee--wwoorrdd ((MM--ll)) + Lowercase the current (or following) word. With a negative + argument, lowercase the previous word, but do not move point. + ccaappiittaalliizzee--wwoorrdd ((MM--cc)) + Capitalize the current (or following) word. With a negative + argument, capitalize the previous word, but do not move point. + oovveerrwwrriittee--mmooddee + Toggle overwrite mode. With an explicit positive numeric argu- + ment, switches to overwrite mode. With an explicit non-positive + numeric argument, switches to insert mode. This command affects + only eemmaaccss mode; vvii mode does overwrite differently. Each call + to _r_e_a_d_l_i_n_e_(_) starts in insert mode. In overwrite mode, charac- + ters bound to sseellff--iinnsseerrtt replace the text at point rather than + pushing the text to the right. Characters bound to bbaacckk-- + wwaarrdd--ddeelleettee--cchhaarr replace the character before point with a + space. By default, this command is unbound. + + KKiilllliinngg aanndd YYaannkkiinngg + kkiillll--lliinnee ((CC--kk)) + Kill the text from point to the end of the line. + bbaacckkwwaarrdd--kkiillll--lliinnee ((CC--xx RRuubboouutt)) + Kill backward to the beginning of the line. + uunniixx--lliinnee--ddiissccaarrdd ((CC--uu)) + Kill backward from point to the beginning of the line. The + killed text is saved on the kill-ring. + kkiillll--wwhhoollee--lliinnee + Kill all characters on the current line, no matter where point + is. + kkiillll--wwoorrdd ((MM--dd)) + Kill from point to the end of the current word, or if between + words, to the end of the next word. Word boundaries are the + same as those used by ffoorrwwaarrdd--wwoorrdd. + bbaacckkwwaarrdd--kkiillll--wwoorrdd ((MM--RRuubboouutt)) + Kill the word behind point. Word boundaries are the same as + those used by bbaacckkwwaarrdd--wwoorrdd. + sshheellll--kkiillll--wwoorrdd ((MM--dd)) + Kill from point to the end of the current word, or if between + words, to the end of the next word. Word boundaries are the + same as those used by sshheellll--ffoorrwwaarrdd--wwoorrdd. + sshheellll--bbaacckkwwaarrdd--kkiillll--wwoorrdd ((MM--RRuubboouutt)) + Kill the word behind point. Word boundaries are the same as + those used by sshheellll--bbaacckkwwaarrdd--wwoorrdd. + uunniixx--wwoorrdd--rruubboouutt ((CC--ww)) + Kill the word behind point, using white space as a word bound- + ary. The killed text is saved on the kill-ring. + uunniixx--ffiilleennaammee--rruubboouutt + Kill the word behind point, using white space and the slash + character as the word boundaries. The killed text is saved on + the kill-ring. + ddeelleettee--hhoorriizzoonnttaall--ssppaaccee ((MM--\\)) + Delete all spaces and tabs around point. + kkiillll--rreeggiioonn + Kill the text in the current region. + ccooppyy--rreeggiioonn--aass--kkiillll + Copy the text in the region to the kill buffer. + ccooppyy--bbaacckkwwaarrdd--wwoorrdd + Copy the word before point to the kill buffer. The word bound- + aries are the same as bbaacckkwwaarrdd--wwoorrdd. + ccooppyy--ffoorrwwaarrdd--wwoorrdd + Copy the word following point to the kill buffer. The word + boundaries are the same as ffoorrwwaarrdd--wwoorrdd. + yyaannkk ((CC--yy)) + Yank the top of the kill ring into the buffer at point. + yyaannkk--ppoopp ((MM--yy)) + Rotate the kill ring, and yank the new top. Only works follow- + ing yyaannkk or yyaannkk--ppoopp. + + NNuummeerriicc AArrgguummeennttss + ddiiggiitt--aarrgguummeenntt ((MM--00,, MM--11,, ......,, MM----)) + Add this digit to the argument already accumulating, or start a + new argument. M-- starts a negative argument. + uunniivveerrssaall--aarrgguummeenntt + This is another way to specify an argument. If this command is + followed by one or more digits, optionally with a leading minus + sign, those digits define the argument. If the command is fol- + lowed by digits, executing uunniivveerrssaall--aarrgguummeenntt again ends the + numeric argument, but is otherwise ignored. As a special case, + if this command is immediately followed by a character that is + neither a digit or minus sign, the argument count for the next + command is multiplied by four. The argument count is initially + one, so executing this function the first time makes the argu- + ment count four, a second time makes the argument count sixteen, + and so on. + + CCoommpplleettiinngg + ccoommpplleettee ((TTAABB)) + Attempt to perform completion on the text before point. BBaasshh + attempts completion treating the text as a variable (if the text + begins with $$), username (if the text begins with ~~), hostname + (if the text begins with @@), or command (including aliases and + functions) in turn. If none of these produces a match, filename + completion is attempted. + ppoossssiibbllee--ccoommpplleettiioonnss ((MM--??)) + List the possible completions of the text before point. + iinnsseerrtt--ccoommpplleettiioonnss ((MM--**)) + Insert all completions of the text before point that would have + been generated by ppoossssiibbllee--ccoommpplleettiioonnss. + mmeennuu--ccoommpplleettee + Similar to ccoommpplleettee, but replaces the word to be completed with + a single match from the list of possible completions. Repeated + execution of mmeennuu--ccoommpplleettee steps through the list of possible + completions, inserting each match in turn. At the end of the + list of completions, the bell is rung (subject to the setting of + bbeellll--ssttyyllee) and the original text is restored. An argument of _n + moves _n positions forward in the list of matches; a negative + argument may be used to move backward through the list. This + command is intended to be bound to TTAABB, but is unbound by + default.cc + mmeennuu--ccoommpplleettee--kkrrdd + Identicwwal to mmeennuu--ccoommpplleettee, but moves backward through the list + of possible completions, as if mmeennuu--ccoommpplleettee had been given a + negative argument. This command is unbound by default. + ddeelleettee--cchhaarr--oorr--lliisstt + Deletes the character under the cursor if not at the beginning + or end of the line (like ddeelleettee--cchhaarr). If at the end of the + line, behaves identically to ppoossssiibbllee--ccoommpplleettiioonnss. This command + is unbound by default. + ccoommpplleettee--ffiilleennaammee ((MM--//)) + Attempt filename completion on the text before point. + ppoossssiibbllee--ffiilleennaammee--ccoommpplleettiioonnss ((CC--xx //)) + List the possible completions of the text before point, treating + it as a filename. + ccoommpplleettee--uusseerrnnaammee ((MM--~~)) + Attempt completion on the text before point, treating it as a + username. + ppoossssiibbllee--uusseerrnnaammee--ccoommpplleettiioonnss ((CC--xx ~~)) + List the possible completions of the text before point, treating + it as a username. + ccoommpplleettee--vvaarriiaabbllee ((MM--$$)) + Attempt completion on the text before point, treating it as a + shell variable. + ppoossssiibbllee--vvaarriiaabbllee--ccoommpplleettiioonnss ((CC--xx $$)) + List the possible completions of the text before point, treating + it as a shell variable. + ccoommpplleettee--hhoossttnnaammee ((MM--@@)) + Attempt completion on the text before point, treating it as a + hostname. + ppoossssiibbllee--hhoossttnnaammee--ccoommpplleettiioonnss ((CC--xx @@)) + List the possible completions of the text before point, treating + it as a hostname. + ccoommpplleettee--ccoommmmaanndd ((MM--!!)) + Attempt completion on the text before point, treating it as a + command name. Command completion attempts to match the text + against aliases, reserved words, shell functions, shell + builtins, and finally executable filenames, in that order. + ppoossssiibbllee--ccoommmmaanndd--ccoommpplleettiioonnss ((CC--xx !!)) + List the possible completions of the text before point, treating + it as a command name. + ddyynnaammiicc--ccoommpplleettee--hhiissttoorryy ((MM--TTAABB)) + Attempt completion on the text before point, comparing the text + against lines from the history list for possible completion + matches. + ddaabbbbrreevv--eexxppaanndd + Attempt menu completion on the text before point, comparing the + text against lines from the history list for possible completion + matches. + ccoommpplleettee--iinnttoo--bbrraacceess ((MM--{{)) + Perform filename completion and insert the list of possible com- + pletions enclosed within braces so the list is available to the + shell (see BBrraaccee EExxppaannssiioonn above). + + KKeeyybbooaarrdd MMaaccrrooss + ssttaarrtt--kkbbdd--mmaaccrroo ((CC--xx (()) + Begin saving the characters typed into the current keyboard + macro. + eenndd--kkbbdd--mmaaccrroo ((CC--xx )))) + Stop saving the characters typed into the current keyboard macro + and store the definition. + ccaallll--llaasstt--kkbbdd--mmaaccrroo ((CC--xx ee)) + Re-execute the last keyboard macro defined, by making the char- + acters in the macro appear as if typed at the keyboard. + + MMiisscceellllaanneeoouuss + rree--rreeaadd--iinniitt--ffiillee ((CC--xx CC--rr)) + Read in the contents of the _i_n_p_u_t_r_c file, and incorporate any + bindings or variable assignments found there. + aabboorrtt ((CC--gg)) + Abort the current editing command and ring the terminal's bell + (subject to the setting of bbeellll--ssttyyllee). + ddoo--uuppppeerrccaassee--vveerrssiioonn ((MM--aa,, MM--bb,, MM--_x,, ......)) + If the metafied character _x is lowercase, run the command that + is bound to the corresponding uppercase character. + pprreeffiixx--mmeettaa ((EESSCC)) + Metafy the next character typed. EESSCC ff is equivalent to MMeettaa--ff. + uunnddoo ((CC--__,, CC--xx CC--uu)) + Incremental undo, separately remembered for each line. + rreevveerrtt--lliinnee ((MM--rr)) + Undo all changes made to this line. This is like executing the + uunnddoo command enough times to return the line to its initial + state. + ttiillddee--eexxppaanndd ((MM--&&)) + Perform tilde expansion on the current word. + sseett--mmaarrkk ((CC--@@,, MM--<<ssppaaccee>>)) + Set the mark to the point. If a numeric argument is supplied, + the mark is set to that position. + eexxcchhaannggee--ppooiinntt--aanndd--mmaarrkk ((CC--xx CC--xx)) + Swap the point with the mark. The current cursor position is + set to the saved position, and the old cursor position is saved + as the mark. + cchhaarraacctteerr--sseeaarrcchh ((CC--]])) + A character is read and point is moved to the next occurrence of + that character. A negative count searches for previous occur- + rences. + cchhaarraacctteerr--sseeaarrcchh--bbaacckkwwaarrdd ((MM--CC--]])) + A character is read and point is moved to the previous occur- + rence of that character. A negative count searches for subse- + quent occurrences. + sskkiipp--ccssii--sseeqquueennccee (()) + Read enough characters to consume a multi-key sequence such as + those defined for keys like Home and End. Such sequences begin + with a Control Sequence Indicator (CSI), usually ESC-[. If this + sequence is bound to "\[", keys producing such sequences will + have no effect unless explicitly bound to a readline command, + instead of inserting stray characters into the editing buffer. + This is unbound by default, but usually bound to ESC-[. + iinnsseerrtt--ccoommmmeenntt ((MM--##)) + Without a numeric argument, the value of the readline ccoomm-- + mmeenntt--bbeeggiinn variable is inserted at the beginning of the current + line. If a numeric argument is supplied, this command acts as a + toggle: if the characters at the beginning of the line do not + match the value of ccoommmmeenntt--bbeeggiinn, the value is inserted, other- + wise the characters in ccoommmmeenntt--bbeeggiinn are deleted from the begin- + ning of the line. In either case, the line is accepted as if a + newline had been typed. The default value of ccoommmmeenntt--bbeeggiinn + causes this command to make the current line a shell comment. + If a numeric argument causes the comment character to be + removed, the line will be executed by the shell. + gglloobb--ccoommpplleettee--wwoorrdd ((MM--gg)) + The word before point is treated as a pattern for pathname + expansion, with an asterisk implicitly appended. This pattern + is used to generate a list of matching file names for possible + completions. + gglloobb--eexxppaanndd--wwoorrdd ((CC--xx **)) + The word before point is treated as a pattern for pathname + expansion, and the list of matching file names is inserted, + replacing the word. If a numeric argument is supplied, an + asterisk is appended before pathname expansion. + gglloobb--lliisstt--eexxppaannssiioonnss ((CC--xx gg)) + The list of expansions that would have been generated by + gglloobb--eexxppaanndd--wwoorrdd is displayed, and the line is redrawn. If a + numeric argument is supplied, an asterisk is appended before + pathname expansion. + dduummpp--ffuunnccttiioonnss + Print all of the functions and their key bindings to the read- + line output stream. If a numeric argument is supplied, the out- + put is formatted in such a way that it can be made part of an + _i_n_p_u_t_r_c file. + dduummpp--vvaarriiaabblleess + Print all of the settable readline variables and their values to + the readline output stream. If a numeric argument is supplied, + the output is formatted in such a way that it can be made part + of an _i_n_p_u_t_r_c file. + dduummpp--mmaaccrrooss + Print all of the readline key sequences bound to macros and the + strings they output. If a numeric argument is supplied, the + output is formatted in such a way that it can be made part of an + _i_n_p_u_t_r_c file. + ddiissppllaayy--sshheellll--vveerrssiioonn ((CC--xx CC--vv)) + Display version information about the current instance of bbaasshh. + + PPrrooggrraammmmaabbllee CCoommpplleettiioonn + When word completion is attempted for an argument to a command for + which a completion specification (a _c_o_m_p_s_p_e_c) has been defined using + the ccoommpplleettee builtin (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below), the pro- + grammable completion facilities are invoked. + + First, the command name is identified. If the command word is the + empty string (completion attempted at the beginning of an empty line), + any compspec defined with the --EE option to ccoommpplleettee is used. If a + compspec has been defined for that command, the compspec is used to + generate the list of possible completions for the word. If the command + word is a full pathname, a compspec for the full pathname is searched + for first. If no compspec is found for the full pathname, an attempt + is made to find a compspec for the portion following the final slash. + If those searches to not result in a compspec, any compspec defined + with the --DD option to ccoommpplleettee is used as the default. + + Once a compspec has been found, it is used to generate the list of + matching words. If a compspec is not found, the default bbaasshh comple- + tion as described above under CCoommpplleettiinngg is performed. + + First, the actions specified by the compspec are used. Only matches + which are prefixed by the word being completed are returned. When the + --ff or --dd option is used for filename or directory name completion, the + shell variable FFIIGGNNOORREE is used to filter the matches. + + Any completions specified by a pathname expansion pattern to the --GG + option are generated next. The words generated by the pattern need not + match the word being completed. The GGLLOOBBIIGGNNOORREE shell variable is not + used to filter the matches, but the FFIIGGNNOORREE variable is used. + + Next, the string specified as the argument to the --WW option is consid- + ered. The string is first split using the characters in the IIFFSS spe- + cial variable as delimiters. Shell quoting is honored. Each word is + then expanded using brace expansion, tilde expansion, parameter and + variable expansion, command substitution, and arithmetic expansion, as + described above under EEXXPPAANNSSIIOONN. The results are split using the rules + described above under WWoorrdd SSpplliittttiinngg. The results of the expansion are + prefix-matched against the word being completed, and the matching words + become the possible completions. + + After these matches have been generated, any shell function or command + specified with the --FF and --CC options is invoked. When the command or + function is invoked, the CCOOMMPP__LLIINNEE, CCOOMMPP__PPOOIINNTT, CCOOMMPP__KKEEYY, and CCOOMMPP__TTYYPPEE + variables are assigned values as described above under SShheellll VVaarriiaabblleess. + If a shell function is being invoked, the CCOOMMPP__WWOORRDDSS and CCOOMMPP__CCWWOORRDD + variables are also set. When the function or command is invoked, the + first argument is the name of the command whose arguments are being + completed, the second argument is the word being completed, and the + third argument is the word preceding the word being completed on the + current command line. No filtering of the generated completions + against the word being completed is performed; the function or command + has complete freedom in generating the matches. + + Any function specified with --FF is invoked first. The function may use + any of the shell facilities, including the ccoommppggeenn builtin described + below, to generate the matches. It must put the possible completions + in the CCOOMMPPRREEPPLLYY array variable. + + Next, any command specified with the --CC option is invoked in an envi- + ronment equivalent to command substitution. It should print a list of + completions, one per line, to the standard output. Backslash may be + used to escape a newline, if necessary. + + After all of the possible completions are generated, any filter speci- + fied with the --XX option is applied to the list. The filter is a pat- + tern as used for pathname expansion; a && in the pattern is replaced + with the text of the word being completed. A literal && may be escaped + with a backslash; the backslash is removed before attempting a match. + Any completion that matches the pattern will be removed from the list. + A leading !! negates the pattern; in this case any completion not match- + ing the pattern will be removed. + + Finally, any prefix and suffix specified with the --PP and --SS options are + added to each member of the completion list, and the result is returned + to the readline completion code as the list of possible completions. + + If the previously-applied actions do not generate any matches, and the + --oo ddiirrnnaammeess option was supplied to ccoommpplleettee when the compspec was + defined, directory name completion is attempted. + + If the --oo pplluussddiirrss option was supplied to ccoommpplleettee when the compspec + was defined, directory name completion is attempted and any matches are + added to the results of the other actions. + + By default, if a compspec is found, whatever it generates is returned + to the completion code as the full set of possible completions. The + default bbaasshh completions are not attempted, and the readline default of + filename completion is disabled. If the --oo bbaasshhddeeffaauulltt option was sup- + plied to ccoommpplleettee when the compspec was defined, the bbaasshh default com- + pletions are attempted if the compspec generates no matches. If the --oo + ddeeffaauulltt option was supplied to ccoommpplleettee when the compspec was defined, + readline's default completion will be performed if the compspec (and, + if attempted, the default bbaasshh completions) generate no matches. + + When a compspec indicates that directory name completion is desired, + the programmable completion functions force readline to append a slash + to completed names which are symbolic links to directories, subject to + the value of the mmaarrkk--ddiirreeccttoorriieess readline variable, regardless of the + setting of the mmaarrkk--ssyymmlliinnkkeedd--ddiirreeccttoorriieess readline variable. + + There is some support for dynamically modifying completions. This is + most useful when used in combination with a default completion speci- + fied with ccoommpplleettee --DD. It's possible for shell functions executed as + completion handlers to indicate that completion should be retried by + returning an exit status of 124. If a shell function returns 124, and + changes the compspec associated with the command on which completion is + being attempted (supplied as the first argument when the function is + executed), programmable completion restarts from the beginning, with an + attempt to find a compspec for that command. This allows a set of com- + pletions to be built dynamically as completion is attempted, rather + than being loaded all at once. + + For instance, assuming that there is a library of compspecs, each kept + in a file corresponding to the name of the command, the following + default completion function would load completions dynamically: + + _completion_loader() + { + . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124 + } + complete -D -F _completion_loader + + +HHIISSTTOORRYY + When the --oo hhiissttoorryy option to the sseett builtin is enabled, the shell + provides access to the _c_o_m_m_a_n_d _h_i_s_t_o_r_y, the list of commands previously + typed. The value of the HHIISSTTSSIIZZEE variable is used as the number of + commands to save in a history list. The text of the last HHIISSTTSSIIZZEE com- + mands (default 500) is saved. The shell stores each command in the + history list prior to parameter and variable expansion (see EEXXPPAANNSSIIOONN + above) but after history expansion is performed, subject to the values + of the shell variables HHIISSTTIIGGNNOORREE and HHIISSTTCCOONNTTRROOLL. + + On startup, the history is initialized from the file named by the vari- + able HHIISSTTFFIILLEE (default _~_/_._b_a_s_h___h_i_s_t_o_r_y). The file named by the value + of HHIISSTTFFIILLEE is truncated, if necessary, to contain no more than the + number of lines specified by the value of HHIISSTTFFIILLEESSIIZZEE. When the his- + tory file is read, lines beginning with the history comment character + followed immediately by a digit are interpreted as timestamps for the + preceding history line. These timestamps are optionally displayed + depending on the value of the HHIISSTTTTIIMMEEFFOORRMMAATT variable. When an inter- + active shell exits, the last $$HHIISSTTSSIIZZEE lines are copied from the his- + tory list to $$HHIISSTTFFIILLEE. If the hhiissttaappppeenndd shell option is enabled (see + the description of sshhoopptt under SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below), the lines + are appended to the history file, otherwise the history file is over- + written. If HHIISSTTFFIILLEE is unset, or if the history file is unwritable, + the history is not saved. If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, time + stamps are written to the history file, marked with the history comment + character, so they may be preserved across shell sessions. This uses + the history comment character to distinguish timestamps from other his- + tory lines. After saving the history, the history file is truncated to + contain no more than HHIISSTTFFIILLEESSIIZZEE lines. If HHIISSTTFFIILLEESSIIZZEE is not set, + no truncation is performed. + + The builtin command ffcc (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below) may be used + to list or edit and re-execute a portion of the history list. The hhiiss-- + ttoorryy builtin may be used to display or modify the history list and + manipulate the history file. When using command-line editing, search + commands are available in each editing mode that provide access to the + history list. + + The shell allows control over which commands are saved on the history + list. The HHIISSTTCCOONNTTRROOLL and HHIISSTTIIGGNNOORREE variables may be set to cause the + shell to save only a subset of the commands entered. The ccmmddhhiisstt shell + option, if enabled, causes the shell to attempt to save each line of a + multi-line command in the same history entry, adding semicolons where + necessary to preserve syntactic correctness. The lliitthhiisstt shell option + causes the shell to save the command with embedded newlines instead of + semicolons. See the description of the sshhoopptt builtin below under SSHHEELLLL + BBUUIILLTTIINN CCOOMMMMAANNDDSS for information on setting and unsetting shell + options. + +HHIISSTTOORRYY EEXXPPAANNSSIIOONN + The shell supports a history expansion feature that is similar to the + history expansion in ccsshh.. This section describes what syntax features + are available. This feature is enabled by default for interactive + shells, and can be disabled using the ++HH option to the sseett builtin com- + mand (see SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS below). Non-interactive shells do not + perform history expansion by default. + + History expansions introduce words from the history list into the input + stream, making it easy to repeat commands, insert the arguments to a + previous command into the current input line, or fix errors in previous + commands quickly. + + History expansion is performed immediately after a complete line is + read, before the shell breaks it into words. It takes place in two + parts. The first is to determine which line from the history list to + use during substitution. The second is to select portions of that line + for inclusion into the current one. The line selected from the history + is the _e_v_e_n_t, and the portions of that line that are acted upon are + _w_o_r_d_s. Various _m_o_d_i_f_i_e_r_s are available to manipulate the selected + words. The line is broken into words in the same fashion as when read- + ing input, so that several _m_e_t_a_c_h_a_r_a_c_t_e_r-separated words surrounded by + quotes are considered one word. History expansions are introduced by + the appearance of the history expansion character, which is !! by + default. Only backslash (\\) and single quotes can quote the history + expansion character. + + Several characters inhibit history expansion if found immediately fol- + lowing the history expansion character, even if it is unquoted: space, + tab, newline, carriage return, and ==. If the eexxttgglloobb shell option is + enabled, (( will also inhibit expansion. + + Several shell options settable with the sshhoopptt builtin may be used to + tailor the behavior of history expansion. If the hhiissttvveerriiffyy shell + option is enabled (see the description of the sshhoopptt builtin below), and + rreeaaddlliinnee is being used, history substitutions are not immediately + passed to the shell parser. Instead, the expanded line is reloaded + into the rreeaaddlliinnee editing buffer for further modification. If rreeaaddlliinnee + is being used, and the hhiissttrreeeeddiitt shell option is enabled, a failed + history substitution will be reloaded into the rreeaaddlliinnee editing buffer + for correction. The --pp option to the hhiissttoorryy builtin command may be + used to see what a history expansion will do before using it. The --ss + option to the hhiissttoorryy builtin may be used to add commands to the end of + the history list without actually executing them, so that they are + available for subsequent recall. + + The shell allows control of the various characters used by the history + expansion mechanism (see the description of hhiissttcchhaarrss above under SShheellll + VVaarriiaabblleess). The shell uses the history comment character to mark his- + tory timestamps when writing the history file. + + EEvveenntt DDeessiiggnnaattoorrss + An event designator is a reference to a command line entry in the his- + tory list. + + !! Start a history substitution, except when followed by a bbllaannkk, + newline, carriage return, = or ( (when the eexxttgglloobb shell option + is enabled using the sshhoopptt builtin). + !!_n Refer to command line _n. + !!--_n Refer to the current command line minus _n. + !!!! Refer to the previous command. This is a synonym for `!-1'. + !!_s_t_r_i_n_g + Refer to the most recent command starting with _s_t_r_i_n_g. + !!??_s_t_r_i_n_g[[??]] + Refer to the most recent command containing _s_t_r_i_n_g. The trail- + ing ?? may be omitted if _s_t_r_i_n_g is followed immediately by a new- + line. + ^^_s_t_r_i_n_g_1^^_s_t_r_i_n_g_2^^ + Quick substitution. Repeat the last command, replacing _s_t_r_i_n_g_1 + with _s_t_r_i_n_g_2. Equivalent to ``!!:s/_s_t_r_i_n_g_1/_s_t_r_i_n_g_2/'' (see MMoodd-- + iiffiieerrss below). + !!## The entire command line typed so far. + + WWoorrdd DDeessiiggnnaattoorrss + Word designators are used to select desired words from the event. A :: + separates the event specification from the word designator. It may be + omitted if the word designator begins with a ^^, $$, **, --, or %%. Words + are numbered from the beginning of the line, with the first word being + denoted by 0 (zero). Words are inserted into the current line sepa- + rated by single spaces. + + 00 ((zzeerroo)) + The zeroth word. For the shell, this is the command word. + _n The _nth word. + ^^ The first argument. That is, word 1. + $$ The last argument. + %% The word matched by the most recent `?_s_t_r_i_n_g?' search. + _x--_y A range of words; `-_y' abbreviates `0-_y'. + ** All of the words but the zeroth. This is a synonym for `_1_-_$'. + It is not an error to use ** if there is just one word in the + event; the empty string is returned in that case. + xx** Abbreviates _x_-_$. + xx-- Abbreviates _x_-_$ like xx**, but omits the last word. + + If a word designator is supplied without an event specification, the + previous command is used as the event. + + MMooddiiffiieerrss + After the optional word designator, there may appear a sequence of one + or more of the following modifiers, each preceded by a `:'. + + hh Remove a trailing file name component, leaving only the head. + tt Remove all leading file name components, leaving the tail. + rr Remove a trailing suffix of the form _._x_x_x, leaving the basename. + ee Remove all but the trailing suffix. + pp Print the new command but do not execute it. + qq Quote the substituted words, escaping further substitutions. + xx Quote the substituted words as with qq, but break into words at + bbllaannkkss and newlines. + ss//_o_l_d//_n_e_w// + Substitute _n_e_w for the first occurrence of _o_l_d in the event + line. Any delimiter can be used in place of /. The final + delimiter is optional if it is the last character of the event + line. The delimiter may be quoted in _o_l_d and _n_e_w with a single + backslash. If & appears in _n_e_w, it is replaced by _o_l_d. A sin- + gle backslash will quote the &. If _o_l_d is null, it is set to + the last _o_l_d substituted, or, if no previous history substitu- + tions took place, the last _s_t_r_i_n_g in a !!??_s_t_r_i_n_g[[??]] search. + && Repeat the previous substitution. + gg Cause changes to be applied over the entire event line. This is + used in conjunction with `::ss' (e.g., `::ggss//_o_l_d//_n_e_w//') or `::&&'. + If used with `::ss', any delimiter can be used in place of /, and + the final delimiter is optional if it is the last character of + the event line. An aa may be used as a synonym for gg. + GG Apply the following `ss' modifier once to each word in the event + line. + +SSHHEELLLL BBUUIILLTTIINN CCOOMMMMAANNDDSS + Unless otherwise noted, each builtin command documented in this section + as accepting options preceded by -- accepts ---- to signify the end of the + options. The ::, ttrruuee, ffaallssee, and tteesstt builtins do not accept options + and do not treat ---- specially. The eexxiitt, llooggoouutt, bbrreeaakk, ccoonnttiinnuuee, lleett, + and sshhiifftt builtins accept and process arguments beginning with -- with- + out requiring ----. Other builtins that accept arguments but are not + specified as accepting options interpret arguments beginning with -- as + invalid options and require ---- to prevent this interpretation. + :: [_a_r_g_u_m_e_n_t_s] + No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s + and performing any specified redirections. A zero exit code is + returned. + + .. _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] + ssoouurrccee _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] + Read and execute commands from _f_i_l_e_n_a_m_e in the current shell + environment and return the exit status of the last command exe- + cuted from _f_i_l_e_n_a_m_e. If _f_i_l_e_n_a_m_e does not contain a slash, file + names in PPAATTHH are used to find the directory containing _f_i_l_e_- + _n_a_m_e. The file searched for in PPAATTHH need not be executable. + When bbaasshh is not in _p_o_s_i_x _m_o_d_e, the current directory is + searched if no file is found in PPAATTHH. If the ssoouurrcceeppaatthh option + to the sshhoopptt builtin command is turned off, the PPAATTHH is not + searched. If any _a_r_g_u_m_e_n_t_s are supplied, they become the posi- + tional parameters when _f_i_l_e_n_a_m_e is executed. Otherwise the + positional parameters are unchanged. The return status is the + status of the last command exited within the script (0 if no + commands are executed), and false if _f_i_l_e_n_a_m_e is not found or + cannot be read. + + aalliiaass [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] + AAlliiaass with no arguments or with the --pp option prints the list of + aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. When + arguments are supplied, an alias is defined for each _n_a_m_e whose + _v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word + to be checked for alias substitution when the alias is expanded. + For each _n_a_m_e in the argument list for which no _v_a_l_u_e is sup- + plied, the name and value of the alias is printed. AAlliiaass + returns true unless a _n_a_m_e is given for which no alias has been + defined. + + bbgg [_j_o_b_s_p_e_c ...] + Resume each suspended job _j_o_b_s_p_e_c in the background, as if it + had been started with &&. If _j_o_b_s_p_e_c is not present, the shell's + notion of the _c_u_r_r_e_n_t _j_o_b is used. bbgg _j_o_b_s_p_e_c returns 0 unless + run when job control is disabled or, when run with job control + enabled, any specified _j_o_b_s_p_e_c was not found or was started + without job control. + + bbiinndd [--mm _k_e_y_m_a_p] [--llppssvvPPSSVV] + bbiinndd [--mm _k_e_y_m_a_p] [--qq _f_u_n_c_t_i_o_n] [--uu _f_u_n_c_t_i_o_n] [--rr _k_e_y_s_e_q] + bbiinndd [--mm _k_e_y_m_a_p] --ff _f_i_l_e_n_a_m_e + bbiinndd [--mm _k_e_y_m_a_p] --xx _k_e_y_s_e_q:_s_h_e_l_l_-_c_o_m_m_a_n_d + bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_f_u_n_c_t_i_o_n_-_n_a_m_e + bbiinndd _r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d + Display current rreeaaddlliinnee key and function bindings, bind a key + sequence to a rreeaaddlliinnee function or macro, or set a rreeaaddlliinnee + variable. Each non-option argument is a command as it would + appear in _._i_n_p_u_t_r_c, but each binding or command must be passed + as a separate argument; e.g., '"\C-x\C-r": re-read-init-file'. + Options, if supplied, have the following meanings: + --mm _k_e_y_m_a_p + Use _k_e_y_m_a_p as the keymap to be affected by the subsequent + bindings. Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_- + _d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d, + and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is + equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d. + --ll List the names of all rreeaaddlliinnee functions. + --pp Display rreeaaddlliinnee function names and bindings in such a + way that they can be re-read. + --PP List current rreeaaddlliinnee function names and bindings. + --ss Display rreeaaddlliinnee key sequences bound to macros and the + strings they output in such a way that they can be re- + read. + --SS Display rreeaaddlliinnee key sequences bound to macros and the + strings they output. + --vv Display rreeaaddlliinnee variable names and values in such a way + that they can be re-read. + --VV List current rreeaaddlliinnee variable names and values. + --ff _f_i_l_e_n_a_m_e + Read key bindings from _f_i_l_e_n_a_m_e. + --qq _f_u_n_c_t_i_o_n + Query about which keys invoke the named _f_u_n_c_t_i_o_n. + --uu _f_u_n_c_t_i_o_n + Unbind all keys bound to the named _f_u_n_c_t_i_o_n. + --rr _k_e_y_s_e_q + Remove any current binding for _k_e_y_s_e_q. + --xx _k_e_y_s_e_q::_s_h_e_l_l_-_c_o_m_m_a_n_d + Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be executed whenever _k_e_y_s_e_q is + entered. When _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets + the RREEAADDLLIINNEE__LLIINNEE variable to the contents of the rreeaadd-- + lliinnee line buffer and the RREEAADDLLIINNEE__PPOOIINNTT variable to the + current location of the insertion point. If the executed + command changes the value of RREEAADDLLIINNEE__LLIINNEE or RREEAADD-- + LLIINNEE__PPOOIINNTT, those new values will be reflected in the + editing state. + + The return value is 0 unless an unrecognized option is given or + an error occurred. + + bbrreeaakk [_n] + Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is + specified, break _n levels. _n must be >= 1. If _n is greater + than the number of enclosing loops, all enclosing loops are + exited. The return value is 0 unless _n is not greater than or + equal to 1. + + bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s] + Execute the specified shell builtin, passing it _a_r_g_u_m_e_n_t_s, and + return its exit status. This is useful when defining a function + whose name is the same as a shell builtin, retaining the func- + tionality of the builtin within the function. The ccdd builtin is + commonly redefined this way. The return status is false if + _s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command. + + ccaalllleerr [_e_x_p_r] + Returns the context of any active subroutine call (a shell func- + tion or a script executed with the .. or ssoouurrccee builtins. With- + out _e_x_p_r, ccaalllleerr displays the line number and source filename of + the current subroutine call. If a non-negative integer is sup- + plied as _e_x_p_r, ccaalllleerr displays the line number, subroutine name, + and source file corresponding to that position in the current + execution call stack. This extra information may be used, for + example, to print a stack trace. The current frame is frame 0. + The return value is 0 unless the shell is not executing a sub- + routine call or _e_x_p_r does not correspond to a valid position in + the call stack. + + ccdd [--LL||--PP] [_d_i_r] + Change the current directory to _d_i_r. The variable HHOOMMEE is the + default _d_i_r. The variable CCDDPPAATTHH defines the search path for + the directory containing _d_i_r. Alternative directory names in + CCDDPPAATTHH are separated by a colon (:). A null directory name in + CCDDPPAATTHH is the same as the current directory, i.e., ``..''. If + _d_i_r begins with a slash (/), then CCDDPPAATTHH is not used. The --PP + option says to use the physical directory structure instead of + following symbolic links (see also the --PP option to the sseett + builtin command); the --LL option forces symbolic links to be fol- + lowed. An argument of -- is equivalent to $$OOLLDDPPWWDD. If a non- + empty directory name from CCDDPPAATTHH is used, or if -- is the first + argument, and the directory change is successful, the absolute + pathname of the new working directory is written to the standard + output. The return value is true if the directory was success- + fully changed; false otherwise. + + ccoommmmaanndd [--ppVVvv] _c_o_m_m_a_n_d [_a_r_g ...] + Run _c_o_m_m_a_n_d with _a_r_g_s suppressing the normal shell function + lookup. Only builtin commands or commands found in the PPAATTHH are + executed. If the --pp option is given, the search for _c_o_m_m_a_n_d is + performed using a default value for PPAATTHH that is guaranteed to + find all of the standard utilities. If either the --VV or --vv + option is supplied, a description of _c_o_m_m_a_n_d is printed. The --vv + option causes a single word indicating the command or file name + used to invoke _c_o_m_m_a_n_d to be displayed; the --VV option produces a + more verbose description. If the --VV or --vv option is supplied, + the exit status is 0 if _c_o_m_m_a_n_d was found, and 1 if not. If + neither option is supplied and an error occurred or _c_o_m_m_a_n_d can- + not be found, the exit status is 127. Otherwise, the exit sta- + tus of the ccoommmmaanndd builtin is the exit status of _c_o_m_m_a_n_d. + + ccoommppggeenn [_o_p_t_i_o_n] [_w_o_r_d] + Generate possible completion matches for _w_o_r_d according to the + _o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee + builtin with the exception of --pp and --rr, and write the matches + to the standard output. When using the --FF or --CC options, the + various shell variables set by the programmable completion + facilities, while available, will not have useful values. + + The matches will be generated in the same way as if the pro- + grammable completion code had generated them directly from a + completion specification with the same flags. If _w_o_r_d is speci- + fied, only those completions matching _w_o_r_d will be displayed. + + The return value is true unless an invalid option is supplied, + or no matches were generated. + + ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--DDEE] [--AA _a_c_t_i_o_n] [--GG _g_l_o_b_- + _p_a_t] [--WW _w_o_r_d_l_i_s_t] [--FF _f_u_n_c_t_i_o_n] [--CC _c_o_m_m_a_n_d] + [--XX _f_i_l_t_e_r_p_a_t] [--PP _p_r_e_f_i_x] [--SS _s_u_f_f_i_x] _n_a_m_e [_n_a_m_e _._._.] + ccoommpplleettee --pprr [--DDEE] [_n_a_m_e ...] + Specify how arguments to each _n_a_m_e should be completed. If the + --pp option is supplied, or if no options are supplied, existing + completion specifications are printed in a way that allows them + to be reused as input. The --rr option removes a completion spec- + ification for each _n_a_m_e, or, if no _n_a_m_es are supplied, all com- + pletion specifications. The --DD option indicates that the + remaining options and actions should apply to the ``default'' + command completion; that is, completion attempted on a command + for which no completion has previously been defined. The --EE + option indicates that the remaining options and actions should + apply to ``empty'' command completion; that is, completion + attempted on a blank line. + + The process of applying these completion specifications when + word completion is attempted is described above under PPrroo-- + ggrraammmmaabbllee CCoommpplleettiioonn. + + Other options, if specified, have the following meanings. The + arguments to the --GG, --WW, and --XX options (and, if necessary, the + --PP and --SS options) should be quoted to protect them from expan- + sion before the ccoommpplleettee builtin is invoked. + --oo _c_o_m_p_-_o_p_t_i_o_n + The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp- + spec's behavior beyond the simple generation of comple- + tions. _c_o_m_p_-_o_p_t_i_o_n may be one of: + bbaasshhddeeffaauulltt + Perform the rest of the default bbaasshh completions + if the compspec generates no matches. + ddeeffaauulltt Use readline's default filename completion if + the compspec generates no matches. + ddiirrnnaammeess + Perform directory name completion if the comp- + spec generates no matches. + ffiilleennaammeess + Tell readline that the compspec generates file- + names, so it can perform any filename-specific + processing (like adding a slash to directory + names, quoting special characters, or suppress- + ing trailing spaces). Intended to be used with + shell functions. + nnoossppaaccee Tell readline not to append a space (the + default) to words completed at the end of the + line. + pplluussddiirrss + After any matches defined by the compspec are + generated, directory name completion is + attempted and any matches are added to the + results of the other actions. + --AA _a_c_t_i_o_n + The _a_c_t_i_o_n may be one of the following to generate a + list of possible completions: + aalliiaass Alias names. May also be specified as --aa. + aarrrraayyvvaarr + Array variable names. + bbiinnddiinngg RReeaaddlliinnee key binding names. + bbuuiillttiinn Names of shell builtin commands. May also be + specified as --bb. + ccoommmmaanndd Command names. May also be specified as --cc. + ddiirreeccttoorryy + Directory names. May also be specified as --dd. + ddiissaabblleedd + Names of disabled shell builtins. + eennaabblleedd Names of enabled shell builtins. + eexxppoorrtt Names of exported shell variables. May also be + specified as --ee. + ffiillee File names. May also be specified as --ff. + ffuunnccttiioonn + Names of shell functions. + ggrroouupp Group names. May also be specified as --gg. + hheellppttooppiicc + Help topics as accepted by the hheellpp builtin. + hhoossttnnaammee + Hostnames, as taken from the file specified by + the HHOOSSTTFFIILLEE shell variable. + jjoobb Job names, if job control is active. May also + be specified as --jj. + kkeeyywwoorrdd Shell reserved words. May also be specified as + --kk. + rruunnnniinngg Names of running jobs, if job control is active. + sseerrvviiccee Service names. May also be specified as --ss. + sseettoopptt Valid arguments for the --oo option to the sseett + builtin. + sshhoopptt Shell option names as accepted by the sshhoopptt + builtin. + ssiiggnnaall Signal names. + ssttooppppeedd Names of stopped jobs, if job control is active. + uusseerr User names. May also be specified as --uu. + vvaarriiaabbllee + Names of all shell variables. May also be spec- + ified as --vv. + --GG _g_l_o_b_p_a_t + The pathname expansion pattern _g_l_o_b_p_a_t is expanded to + generate the possible completions. + --WW _w_o_r_d_l_i_s_t + The _w_o_r_d_l_i_s_t is split using the characters in the IIFFSS + special variable as delimiters, and each resultant word + is expanded. The possible completions are the members + of the resultant list which match the word being com- + pleted. + --CC _c_o_m_m_a_n_d + _c_o_m_m_a_n_d is executed in a subshell environment, and its + output is used as the possible completions. + --FF _f_u_n_c_t_i_o_n + The shell function _f_u_n_c_t_i_o_n is executed in the current + shell environment. When it finishes, the possible com- + pletions are retrieved from the value of the CCOOMMPPRREEPPLLYY + array variable. + --XX _f_i_l_t_e_r_p_a_t + _f_i_l_t_e_r_p_a_t is a pattern as used for pathname expansion. + It is applied to the list of possible completions gener- + ated by the preceding options and arguments, and each + completion matching _f_i_l_t_e_r_p_a_t is removed from the list. + A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this + case, any completion not matching _f_i_l_t_e_r_p_a_t is removed. + --PP _p_r_e_f_i_x + _p_r_e_f_i_x is added at the beginning of each possible com- + pletion after all other options have been applied. + --SS _s_u_f_f_i_x + _s_u_f_f_i_x is appended to each possible completion after all + other options have been applied. + + The return value is true unless an invalid option is supplied, + an option other than --pp or --rr is supplied without a _n_a_m_e argu- + ment, an attempt is made to remove a completion specification + for a _n_a_m_e for which no specification exists, or an error occurs + adding a completion specification. + + ccoommppoopptt [--oo _o_p_t_i_o_n] [--DDEE] [++oo _o_p_t_i_o_n] [_n_a_m_e] + Modify completion options for each _n_a_m_e according to the + _o_p_t_i_o_ns, or for the currently-execution completion if no _n_a_m_es + are supplied. If no _o_p_t_i_o_ns are given, display the completion + options for each _n_a_m_e or the current completion. The possible + values of _o_p_t_i_o_n are those valid for the ccoommpplleettee builtin + described above. The --DD option indicates that the remaining + options should apply to the ``default'' command completion; that + is, completion attempted on a command for which no completion + has previously been defined. The --EE option indicates that the + remaining options should apply to ``empty'' command completion; + that is, completion attempted on a blank line. + + The return value is true unless an invalid option is supplied, an + attempt is made to modify the options for a _n_a_m_e for which no comple- + tion specification exists, or an output error occurs. + + ccoonnttiinnuuee [_n] + Resume the next iteration of the enclosing ffoorr, wwhhiillee, uunnttiill, or + sseelleecctt loop. If _n is specified, resume at the _nth enclosing + loop. _n must be >= 1. If _n is greater than the number of + enclosing loops, the last enclosing loop (the ``top-level'' + loop) is resumed. The return value is 0 unless _n is not greater + than or equal to 1. + + ddeeccllaarree [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] + ttyyppeesseett [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] + Declare variables and/or give them attributes. If no _n_a_m_es are + given then display the values of variables. The --pp option will + display the attributes and values of each _n_a_m_e. When --pp is used + with _n_a_m_e arguments, additional options are ignored. When --pp is + supplied without _n_a_m_e arguments, it will display the attributes + and values of all variables having the attributes specified by + the additional options. If no other options are supplied with + --pp, ddeeccllaarree will display the attributes and values of all shell + variables. The --ff option will restrict the display to shell + functions. The --FF option inhibits the display of function defi- + nitions; only the function name and attributes are printed. If + the eexxttddeebbuugg shell option is enabled using sshhoopptt, the source + file name and line number where the function is defined are dis- + played as well. The --FF option implies --ff. The following + options can be used to restrict output to variables with the + specified attribute or to give variables attributes: + --aa Each _n_a_m_e is an indexed array variable (see AArrrraayyss + above). + --AA Each _n_a_m_e is an associative array variable (see AArrrraayyss + above). + --ff Use function names only. + --ii The variable is treated as an integer; arithmetic evalua- + tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed when + the variable is assigned a value. + --ll When the variable is assigned a value, all upper-case + characters are converted to lower-case. The upper-case + attribute is disabled. + --rr Make _n_a_m_es readonly. These names cannot then be assigned + values by subsequent assignment statements or unset. + --tt Give each _n_a_m_e the _t_r_a_c_e attribute. Traced functions + inherit the DDEEBBUUGG and RREETTUURRNN traps from the calling + shell. The trace attribute has no special meaning for + variables. + --uu When the variable is assigned a value, all lower-case + characters are converted to upper-case. The lower-case + attribute is disabled. + --xx Mark _n_a_m_es for export to subsequent commands via the + environment. + + Using `+' instead of `-' turns off the attribute instead, with + the exceptions that ++aa may not be used to destroy an array vari- + able and ++rr will not remove the readonly attribute. When used + in a function, makes each _n_a_m_e local, as with the llooccaall command. + If a variable name is followed by =_v_a_l_u_e, the value of the vari- + able is set to _v_a_l_u_e. The return value is 0 unless an invalid + option is encountered, an attempt is made to define a function + using ``-f foo=bar'', an attempt is made to assign a value to a + readonly variable, an attempt is made to assign a value to an + array variable without using the compound assignment syntax (see + AArrrraayyss above), one of the _n_a_m_e_s is not a valid shell variable + name, an attempt is made to turn off readonly status for a read- + only variable, an attempt is made to turn off array status for + an array variable, or an attempt is made to display a non-exis- + tent function with --ff. + + ddiirrss [[++_n]] [[--_n]] [[--ccppllvv]] + Without options, displays the list of currently remembered + directories. The default display is on a single line with + directory names separated by spaces. Directories are added to + the list with the ppuusshhdd command; the ppooppdd command removes + entries from the list. + ++_n Displays the _nth entry counting from the left of the list + shown by ddiirrss when invoked without options, starting with + zero. + --_n Displays the _nth entry counting from the right of the + list shown by ddiirrss when invoked without options, starting + with zero. + --cc Clears the directory stack by deleting all of the + entries. + --ll Produces a longer listing; the default listing format + uses a tilde to denote the home directory. + --pp Print the directory stack with one entry per line. + --vv Print the directory stack with one entry per line, pre- + fixing each entry with its index in the stack. + + The return value is 0 unless an invalid option is supplied or _n + indexes beyond the end of the directory stack. + + ddiissoowwnn [--aarr] [--hh] [_j_o_b_s_p_e_c ...] + Without options, each _j_o_b_s_p_e_c is removed from the table of + active jobs. If _j_o_b_s_p_e_c is not present, and neither --aa nor --rr + is supplied, the shell's notion of the _c_u_r_r_e_n_t _j_o_b is used. If + the --hh option is given, each _j_o_b_s_p_e_c is not removed from the ta- + ble, but is marked so that SSIIGGHHUUPP is not sent to the job if the + shell receives a SSIIGGHHUUPP. If no _j_o_b_s_p_e_c is present, and neither + the --aa nor the --rr option is supplied, the _c_u_r_r_e_n_t _j_o_b is used. + If no _j_o_b_s_p_e_c is supplied, the --aa option means to remove or mark + all jobs; the --rr option without a _j_o_b_s_p_e_c argument restricts + operation to running jobs. The return value is 0 unless a _j_o_b_- + _s_p_e_c does not specify a valid job. + + eecchhoo [--nneeEE] [_a_r_g ...] + Output the _a_r_gs, separated by spaces, followed by a newline. + The return status is always 0. If --nn is specified, the trailing + newline is suppressed. If the --ee option is given, interpreta- + tion of the following backslash-escaped characters is enabled. + The --EE option disables the interpretation of these escape char- + acters, even on systems where they are interpreted by default. + The xxppgg__eecchhoo shell option may be used to dynamically determine + whether or not eecchhoo expands these escape characters by default. + eecchhoo does not interpret ---- to mean the end of options. eecchhoo + interprets the following escape sequences: + \\aa alert (bell) + \\bb backspace + \\cc suppress further output + \\ee an escape character + \\ff form feed + \\nn new line + \\rr carriage return + \\tt horizontal tab + \\vv vertical tab + \\\\ backslash + \\00_n_n_n the eight-bit character whose value is the octal value + _n_n_n (zero to three octal digits) + \\xx_H_H the eight-bit character whose value is the hexadecimal + value _H_H (one or two hex digits) + + eennaabbllee [--aa] [--ddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...] + Enable and disable builtin shell commands. Disabling a builtin + allows a disk command which has the same name as a shell builtin + to be executed without specifying a full pathname, even though + the shell normally searches for builtins before disk commands. + If --nn is used, each _n_a_m_e is disabled; otherwise, _n_a_m_e_s are + enabled. For example, to use the tteesstt binary found via the PPAATTHH + instead of the shell builtin version, run ``enable -n test''. + The --ff option means to load the new builtin command _n_a_m_e from + shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading. + The --dd option will delete a builtin previously loaded with --ff. + If no _n_a_m_e arguments are given, or if the --pp option is supplied, + a list of shell builtins is printed. With no other option argu- + ments, the list consists of all enabled shell builtins. If --nn + is supplied, only disabled builtins are printed. If --aa is sup- + plied, the list printed includes all builtins, with an indica- + tion of whether or not each is enabled. If --ss is supplied, the + output is restricted to the POSIX _s_p_e_c_i_a_l builtins. The return + value is 0 unless a _n_a_m_e is not a shell builtin or there is an + error loading a new builtin from a shared object. + + eevvaall [_a_r_g ...] + The _a_r_gs are read and concatenated together into a single com- + mand. This command is then read and executed by the shell, and + its exit status is returned as the value of eevvaall. If there are + no _a_r_g_s, or only null arguments, eevvaall returns 0. + + eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]] + If _c_o_m_m_a_n_d is specified, it replaces the shell. No new process + is created. The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d. If + the --ll option is supplied, the shell places a dash at the begin- + ning of the zeroth argument passed to _c_o_m_m_a_n_d. This is what + _l_o_g_i_n(1) does. The --cc option causes _c_o_m_m_a_n_d to be executed with + an empty environment. If --aa is supplied, the shell passes _n_a_m_e + as the zeroth argument to the executed command. If _c_o_m_m_a_n_d can- + not be executed for some reason, a non-interactive shell exits, + unless the shell option eexxeeccffaaiill is enabled, in which case it + returns failure. An interactive shell returns failure if the + file cannot be executed. If _c_o_m_m_a_n_d is not specified, any redi- + rections take effect in the current shell, and the return status + is 0. If there is a redirection error, the return status is 1. + + eexxiitt [_n] + Cause the shell to exit with a status of _n. If _n is omitted, + the exit status is that of the last command executed. A trap on + EEXXIITT is executed before the shell terminates. + + eexxppoorrtt [--ffnn] [_n_a_m_e[=_w_o_r_d]] ... + eexxppoorrtt --pp + The supplied _n_a_m_e_s are marked for automatic export to the envi- + ronment of subsequently executed commands. If the --ff option is + given, the _n_a_m_e_s refer to functions. If no _n_a_m_e_s are given, or + if the --pp option is supplied, a list of all names that are + exported in this shell is printed. The --nn option causes the + export property to be removed from each _n_a_m_e. If a variable + name is followed by =_w_o_r_d, the value of the variable is set to + _w_o_r_d. eexxppoorrtt returns an exit status of 0 unless an invalid + option is encountered, one of the _n_a_m_e_s is not a valid shell + variable name, or --ff is supplied with a _n_a_m_e that is not a func- + tion. + + ffcc [--ee _e_n_a_m_e] [--llnnrr] [_f_i_r_s_t] [_l_a_s_t] + ffcc --ss [_p_a_t=_r_e_p] [_c_m_d] + Fix Command. In the first form, a range of commands from _f_i_r_s_t + to _l_a_s_t is selected from the history list. _F_i_r_s_t and _l_a_s_t may + be specified as a string (to locate the last command beginning + with that string) or as a number (an index into the history + list, where a negative number is used as an offset from the cur- + rent command number). If _l_a_s_t is not specified it is set to the + current command for listing (so that ``fc -l -10'' prints the + last 10 commands) and to _f_i_r_s_t otherwise. If _f_i_r_s_t is not spec- + ified it is set to the previous command for editing and -16 for + listing. + + The --nn option suppresses the command numbers when listing. The + --rr option reverses the order of the commands. If the --ll option + is given, the commands are listed on standard output. Other- + wise, the editor given by _e_n_a_m_e is invoked on a file containing + those commands. If _e_n_a_m_e is not given, the value of the FFCCEEDDIITT + variable is used, and the value of EEDDIITTOORR if FFCCEEDDIITT is not set. + If neither variable is set, _v_i is used. When editing is com- + plete, the edited commands are echoed and executed. + + In the second form, _c_o_m_m_a_n_d is re-executed after each instance + of _p_a_t is replaced by _r_e_p. A useful alias to use with this is + ``r="fc -s"'', so that typing ``r cc'' runs the last command + beginning with ``cc'' and typing ``r'' re-executes the last com- + mand. + + If the first form is used, the return value is 0 unless an + invalid option is encountered or _f_i_r_s_t or _l_a_s_t specify history + lines out of range. If the --ee option is supplied, the return + value is the value of the last command executed or failure if an + error occurs with the temporary file of commands. If the second + form is used, the return status is that of the command re-exe- + cuted, unless _c_m_d does not specify a valid history line, in + which case ffcc returns failure. + + ffgg [_j_o_b_s_p_e_c] + Resume _j_o_b_s_p_e_c in the foreground, and make it the current job. + If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b + is used. The return value is that of the command placed into + the foreground, or failure if run when job control is disabled + or, when run with job control enabled, if _j_o_b_s_p_e_c does not spec- + ify a valid job or _j_o_b_s_p_e_c specifies a job that was started + without job control. + + ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g_s] + ggeettooppttss is used by shell procedures to parse positional parame- + ters. _o_p_t_s_t_r_i_n_g contains the option characters to be recog- + nized; if a character is followed by a colon, the option is + expected to have an argument, which should be separated from it + by white space. The colon and question mark characters may not + be used as option characters. Each time it is invoked, ggeettooppttss + places the next option in the shell variable _n_a_m_e, initializing + _n_a_m_e if it does not exist, and the index of the next argument to + be processed into the variable OOPPTTIINNDD. OOPPTTIINNDD is initialized to + 1 each time the shell or a shell script is invoked. When an + option requires an argument, ggeettooppttss places that argument into + the variable OOPPTTAARRGG. The shell does not reset OOPPTTIINNDD automati- + cally; it must be manually reset between multiple calls to + ggeettooppttss within the same shell invocation if a new set of parame- + ters is to be used. + + When the end of options is encountered, ggeettooppttss exits with a + return value greater than zero. OOPPTTIINNDD is set to the index of + the first non-option argument, and nnaammee is set to ?. + + ggeettooppttss normally parses the positional parameters, but if more + arguments are given in _a_r_g_s, ggeettooppttss parses those instead. + + ggeettooppttss can report errors in two ways. If the first character + of _o_p_t_s_t_r_i_n_g is a colon, _s_i_l_e_n_t error reporting is used. In + normal operation diagnostic messages are printed when invalid + options or missing option arguments are encountered. If the + variable OOPPTTEERRRR is set to 0, no error messages will be dis- + played, even if the first character of _o_p_t_s_t_r_i_n_g is not a colon. + + If an invalid option is seen, ggeettooppttss places ? into _n_a_m_e and, if + not silent, prints an error message and unsets OOPPTTAARRGG. If + ggeettooppttss is silent, the option character found is placed in + OOPPTTAARRGG and no diagnostic message is printed. + + If a required argument is not found, and ggeettooppttss is not silent, + a question mark (??) is placed in _n_a_m_e, OOPPTTAARRGG is unset, and a + diagnostic message is printed. If ggeettooppttss is silent, then a + colon (::) is placed in _n_a_m_e and OOPPTTAARRGG is set to the option + character found. + + ggeettooppttss returns true if an option, specified or unspecified, is + found. It returns false if the end of options is encountered or + an error occurs. + + hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e] + For each _n_a_m_e, the full file name of the command is determined + by searching the directories in $$PPAATTHH and remembered. If the --pp + option is supplied, no path search is performed, and _f_i_l_e_n_a_m_e is + used as the full file name of the command. The --rr option causes + the shell to forget all remembered locations. The --dd option + causes the shell to forget the remembered location of each _n_a_m_e. + If the --tt option is supplied, the full pathname to which each + _n_a_m_e corresponds is printed. If multiple _n_a_m_e arguments are + supplied with --tt, the _n_a_m_e is printed before the hashed full + pathname. The --ll option causes output to be displayed in a for- + mat that may be reused as input. If no arguments are given, or + if only --ll is supplied, information about remembered commands is + printed. The return status is true unless a _n_a_m_e is not found + or an invalid option is supplied. + + hheellpp [--ddmmss] [_p_a_t_t_e_r_n] + Display helpful information about builtin commands. If _p_a_t_t_e_r_n + is specified, hheellpp gives detailed help on all commands matching + _p_a_t_t_e_r_n; otherwise help for all the builtins and shell control + structures is printed. + --dd Display a short description of each _p_a_t_t_e_r_n + --mm Display the description of each _p_a_t_t_e_r_n in a manpage-like + format + --ss Display only a short usage synopsis for each _p_a_t_t_e_r_n + The return status is 0 unless no command matches _p_a_t_t_e_r_n. + + hhiissttoorryy [[_n]] + hhiissttoorryy --cc + hhiissttoorryy --dd _o_f_f_s_e_t + hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e] + hhiissttoorryy --pp _a_r_g [_a_r_g _._._.] + hhiissttoorryy --ss _a_r_g [_a_r_g _._._.] + With no options, display the command history list with line num- + bers. Lines listed with a ** have been modified. An argument of + _n lists only the last _n lines. If the shell variable HHIISSTTTTIIMMEE-- + FFOORRMMAATT is set and not null, it is used as a format string for + _s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis- + played history entry. No intervening blank is printed between + the formatted time stamp and the history line. If _f_i_l_e_n_a_m_e is + supplied, it is used as the name of the history file; if not, + the value of HHIISSTTFFIILLEE is used. Options, if supplied, have the + following meanings: + --cc Clear the history list by deleting all the entries. + --dd _o_f_f_s_e_t + Delete the history entry at position _o_f_f_s_e_t. + --aa Append the ``new'' history lines (history lines entered + since the beginning of the current bbaasshh session) to the + history file. + --nn Read the history lines not already read from the history + file into the current history list. These are lines + appended to the history file since the beginning of the + current bbaasshh session. + --rr Read the contents of the history file and use them as the + current history. + --ww Write the current history to the history file, overwrit- + ing the history file's contents. + --pp Perform history substitution on the following _a_r_g_s and + display the result on the standard output. Does not + store the results in the history list. Each _a_r_g must be + quoted to disable normal history expansion. + --ss Store the _a_r_g_s in the history list as a single entry. + The last command in the history list is removed before + the _a_r_g_s are added. + + If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, the time stamp informa- + tion associated with each history entry is written to the his- + tory file, marked with the history comment character. When the + history file is read, lines beginning with the history comment + character followed immediately by a digit are interpreted as + timestamps for the previous history line. The return value is 0 + unless an invalid option is encountered, an error occurs while + reading or writing the history file, an invalid _o_f_f_s_e_t is sup- + plied as an argument to --dd, or the history expansion supplied as + an argument to --pp fails. + + jjoobbss [--llnnpprrss] [ _j_o_b_s_p_e_c ... ] + jjoobbss --xx _c_o_m_m_a_n_d [ _a_r_g_s ... ] + The first form lists the active jobs. The options have the fol- + lowing meanings: + --ll List process IDs in addition to the normal information. + --pp List only the process ID of the job's process group + leader. + --nn Display information only about jobs that have changed + status since the user was last notified of their status. + --rr Restrict output to running jobs. + --ss Restrict output to stopped jobs. + + If _j_o_b_s_p_e_c is given, output is restricted to information about + that job. The return status is 0 unless an invalid option is + encountered or an invalid _j_o_b_s_p_e_c is supplied. + + If the --xx option is supplied, jjoobbss replaces any _j_o_b_s_p_e_c found in + _c_o_m_m_a_n_d or _a_r_g_s with the corresponding process group ID, and + executes _c_o_m_m_a_n_d passing it _a_r_g_s, returning its exit status. + + kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] [_p_i_d | _j_o_b_s_p_e_c] ... + kkiillll --ll [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s] + Send the signal named by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes + named by _p_i_d or _j_o_b_s_p_e_c. _s_i_g_s_p_e_c is either a case-insensitive + signal name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or + a signal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not + present, then SSIIGGTTEERRMM is assumed. An argument of --ll lists the + signal names. If any arguments are supplied when --ll is given, + the names of the signals corresponding to the arguments are + listed, and the return status is 0. The _e_x_i_t___s_t_a_t_u_s argument to + --ll is a number specifying either a signal number or the exit + status of a process terminated by a signal. kkiillll returns true + if at least one signal was successfully sent, or false if an + error occurs or an invalid option is encountered. + + lleett _a_r_g [_a_r_g ...] + Each _a_r_g is an arithmetic expression to be evaluated (see AARRIITTHH-- + MMEETTIICC EEVVAALLUUAATTIIOONN above). If the last _a_r_g evaluates to 0, lleett + returns 1; 0 is returned otherwise. + + llooccaall [_o_p_t_i_o_n] [_n_a_m_e[=_v_a_l_u_e] ...] + For each argument, a local variable named _n_a_m_e is created, and + assigned _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted + by ddeeccllaarree. When llooccaall is used within a function, it causes the + variable _n_a_m_e to have a visible scope restricted to that func- + tion and its children. With no operands, llooccaall writes a list of + local variables to the standard output. It is an error to use + llooccaall when not within a function. The return status is 0 unless + llooccaall is used outside a function, an invalid _n_a_m_e is supplied, + or _n_a_m_e is a readonly variable. + + llooggoouutt Exit a login shell. + + mmaappffiillee [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] + [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] + rreeaaddaarrrraayy [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] + [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] + Read lines from the standard input into the indexed array vari- + able _a_r_r_a_y, or from file descriptor _f_d if the --uu option is sup- + plied. The variable MMAAPPFFIILLEE is the default _a_r_r_a_y. Options, if + supplied, have the following meanings: + --nn Copy at most _c_o_u_n_t lines. If _c_o_u_n_t is 0, all lines are + copied. + --OO Begin assigning to _a_r_r_a_y at index _o_r_i_g_i_n. The default + index is 0. + --ss Discard the first _c_o_u_n_t lines read. + --tt Remove a trailing newline from each line read. + --uu Read lines from file descriptor _f_d instead of the stan- + dard input. + --CC Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read. The + --cc option specifies _q_u_a_n_t_u_m. + --cc Specify the number of lines read between each call to + _c_a_l_l_b_a_c_k. + + If --CC is specified without --cc, the default quantum is 5000. + When _c_a_l_l_b_a_c_k is evaluated, it is supplied the index of the next + array element to be assigned as an additional argument. _c_a_l_l_- + _b_a_c_k is evaluated after the line is read but before the array + element is assigned. + + If not supplied with an explicit origin, mmaappffiillee will clear + _a_r_r_a_y before assigning to it. + + mmaappffiillee returns successfully unless an invalid option or option + argument is supplied, _a_r_r_a_y is invalid or unassignable, or if + _a_r_r_a_y is not an indexed array. + + ppooppdd [-nn] [+_n] [-_n] + Removes entries from the directory stack. With no arguments, + removes the top directory from the stack, and performs a ccdd to + the new top directory. Arguments, if supplied, have the follow- + ing meanings: + --nn Suppresses the normal change of directory when removing + directories from the stack, so that only the stack is + manipulated. + ++_n Removes the _nth entry counting from the left of the list + shown by ddiirrss, starting with zero. For example: ``popd + +0'' removes the first directory, ``popd +1'' the second. + --_n Removes the _nth entry counting from the right of the list + shown by ddiirrss, starting with zero. For example: ``popd + -0'' removes the last directory, ``popd -1'' the next to + last. + + If the ppooppdd command is successful, a ddiirrss is performed as well, + and the return status is 0. ppooppdd returns false if an invalid + option is encountered, the directory stack is empty, a non-exis- + tent directory stack entry is specified, or the directory change + fails. + + pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s] + Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the + control of the _f_o_r_m_a_t. The _f_o_r_m_a_t is a character string which + contains three types of objects: plain characters, which are + simply copied to standard output, character escape sequences, + which are converted and copied to the standard output, and for- + mat specifications, each of which causes printing of the next + successive _a_r_g_u_m_e_n_t. In addition to the standard _p_r_i_n_t_f(1) for- + mats, %%bb causes pprriinnttff to expand backslash escape sequences in + the corresponding _a_r_g_u_m_e_n_t (except that \\cc terminates output, + backslashes in \\'', \\"", and \\?? are not removed, and octal escapes + beginning with \\00 may contain up to four digits), and %%qq causes + pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a format that can + be reused as shell input. + + The --vv option causes the output to be assigned to the variable + _v_a_r rather than being printed to the standard output. + + The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_- + _m_e_n_t_s. If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s than are supplied, + the extra format specifications behave as if a zero value or + null string, as appropriate, had been supplied. The return + value is zero on success, non-zero on failure. + + ppuusshhdd [--nn] [+_n] [-_n] + ppuusshhdd [--nn] [_d_i_r] + Adds a directory to the top of the directory stack, or rotates + the stack, making the new top of the stack the current working + directory. With no arguments, exchanges the top two directories + and returns 0, unless the directory stack is empty. Arguments, + if supplied, have the following meanings: + --nn Suppresses the normal change of directory when adding + directories to the stack, so that only the stack is + manipulated. + ++_n Rotates the stack so that the _nth directory (counting + from the left of the list shown by ddiirrss, starting with + zero) is at the top. + --_n Rotates the stack so that the _nth directory (counting + from the right of the list shown by ddiirrss, starting with + zero) is at the top. + _d_i_r Adds _d_i_r to the directory stack at the top, making it the + new current working directory. + + If the ppuusshhdd command is successful, a ddiirrss is performed as well. + If the first form is used, ppuusshhdd returns 0 unless the cd to _d_i_r + fails. With the second form, ppuusshhdd returns 0 unless the direc- + tory stack is empty, a non-existent directory stack element is + specified, or the directory change to the specified new current + directory fails. + + ppwwdd [--LLPP] + Print the absolute pathname of the current working directory. + The pathname printed contains no symbolic links if the --PP option + is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command + is enabled. If the --LL option is used, the pathname printed may + contain symbolic links. The return status is 0 unless an error + occurs while reading the name of the current directory or an + invalid option is supplied. + + rreeaadd [--eerrss] [--aa _a_n_a_m_e] [--dd _d_e_l_i_m] [--ii _t_e_x_t] [--nn _n_c_h_a_r_s] [--NN _n_c_h_a_r_s] [--pp + _p_r_o_m_p_t] [--tt _t_i_m_e_o_u_t] [--uu _f_d] [_n_a_m_e ...] + One line is read from the standard input, or from the file + descriptor _f_d supplied as an argument to the --uu option, and the + first word is assigned to the first _n_a_m_e, the second word to the + second _n_a_m_e, and so on, with leftover words and their interven- + ing separators assigned to the last _n_a_m_e. If there are fewer + words read from the input stream than names, the remaining names + are assigned empty values. The characters in IIFFSS are used to + split the line into words. The backslash character (\\) may be + used to remove any special meaning for the next character read + and for line continuation. Options, if supplied, have the fol- + lowing meanings: + --aa _a_n_a_m_e + The words are assigned to sequential indices of the array + variable _a_n_a_m_e, starting at 0. _a_n_a_m_e is unset before any + new values are assigned. Other _n_a_m_e arguments are + ignored. + --dd _d_e_l_i_m + The first character of _d_e_l_i_m is used to terminate the + input line, rather than newline. + --ee If the standard input is coming from a terminal, rreeaaddlliinnee + (see RREEAADDLLIINNEE above) is used to obtain the line. Read- + line uses the current (or default, if line editing was + not previously active) editing settings. + --ii _t_e_x_t + If rreeaaddlliinnee is being used to read the line, _t_e_x_t is + placed into the editing buffer before editing begins. + --nn _n_c_h_a_r_s + rreeaadd returns after reading _n_c_h_a_r_s characters rather than + waiting for a complete line of input, but honor a delim- + iter if fewer than _n_c_h_a_r_s characters are read before the + delimiter. + --NN _n_c_h_a_r_s + rreeaadd returns after reading exactly _n_c_h_a_r_s characters + rather than waiting for a complete line of input, unless + EOF is encountered or rreeaadd times out. Delimiter charac- + ters encountered in the input are not treated specially + and do not cause rreeaadd to return until _n_c_h_a_r_s characters + are read. + --pp _p_r_o_m_p_t + Display _p_r_o_m_p_t on standard error, without a trailing new- + line, before attempting to read any input. The prompt is + displayed only if input is coming from a terminal. + --rr Backslash does not act as an escape character. The back- + slash is considered to be part of the line. In particu- + lar, a backslash-newline pair may not be used as a line + continuation. + --ss Silent mode. If input is coming from a terminal, charac- + ters are not echoed. + --tt _t_i_m_e_o_u_t + Cause rreeaadd to time out and return failure if a complete + line of input is not read within _t_i_m_e_o_u_t seconds. _t_i_m_e_- + _o_u_t may be a decimal number with a fractional portion + following the decimal point. This option is only effec- + tive if rreeaadd is reading input from a terminal, pipe, or + other special file; it has no effect when reading from + regular files. If _t_i_m_e_o_u_t is 0, rreeaadd returns success if + input is available on the specified file descriptor, + failure otherwise. The exit status is greater than 128 + if the timeout is exceeded. + --uu _f_d Read input from file descriptor _f_d. + + If no _n_a_m_e_s are supplied, the line read is assigned to the vari- + able RREEPPLLYY. The return code is zero, unless end-of-file is + encountered, rreeaadd times out (in which case the return code is + greater than 128), or an invalid file descriptor is supplied as + the argument to --uu. + + rreeaaddoonnllyy [--aaAAppff] [_n_a_m_e[=_w_o_r_d] ...] + The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s + may not be changed by subsequent assignment. If the --ff option + is supplied, the functions corresponding to the _n_a_m_e_s are so + marked. The --aa option restricts the variables to indexed + arrays; the --AA option restricts the variables to associative + arrays. If no _n_a_m_e arguments are given, or if the --pp option is + supplied, a list of all readonly names is printed. The --pp + option causes output to be displayed in a format that may be + reused as input. If a variable name is followed by =_w_o_r_d, the + value of the variable is set to _w_o_r_d. The return status is 0 + unless an invalid option is encountered, one of the _n_a_m_e_s is not + a valid shell variable name, or --ff is supplied with a _n_a_m_e that + is not a function. + + rreettuurrnn [_n] + Causes a function to exit with the return value specified by _n. + If _n is omitted, the return status is that of the last command + executed in the function body. If used outside a function, but + during execution of a script by the .. (ssoouurrccee) command, it + causes the shell to stop executing that script and return either + _n or the exit status of the last command executed within the + script as the exit status of the script. If used outside a + function and not during execution of a script by .., the return + status is false. Any command associated with the RREETTUURRNN trap is + executed before execution resumes after the function or script. + + sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n] [_a_r_g ...] + sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n] [_a_r_g ...] + Without options, the name and value of each shell variable are + displayed in a format that can be reused as input for setting or + resetting the currently-set variables. Read-only variables can- + not be reset. In _p_o_s_i_x _m_o_d_e, only shell variables are listed. + The output is sorted according to the current locale. When + options are specified, they set or unset shell attributes. Any + arguments remaining after option processing are treated as val- + ues for the positional parameters and are assigned, in order, to + $$11, $$22, ...... $$_n. Options, if specified, have the following + meanings: + --aa Automatically mark variables and functions which are + modified or created for export to the environment of + subsequent commands. + --bb Report the status of terminated background jobs immedi- + ately, rather than before the next primary prompt. This + is effective only when job control is enabled. + --ee Exit immediately if a _p_i_p_e_l_i_n_e (which may consist of a + single _s_i_m_p_l_e _c_o_m_m_a_n_d), a _s_u_b_s_h_e_l_l command enclosed in + parentheses, or one of the commands executed as part of + a command list enclosed by braces (see SSHHEELLLL GGRRAAMMMMAARR + above) exits with a non-zero status. The shell does not + exit if the command that fails is part of the command + list immediately following a wwhhiillee or uunnttiill keyword, + part of the test following the iiff or eelliiff reserved + words, part of any command executed in a &&&& or |||| list + except the command following the final &&&& or ||||, any + command in a pipeline but the last, or if the command's + return value is being inverted with !!. A trap on EERRRR, + if set, is executed before the shell exits. This option + applies to the shell environment and each subshell envi- + ronment separately (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT + above), and may cause subshells to exit before executing + all the commands in the subshell. + --ff Disable pathname expansion. + --hh Remember the location of commands as they are looked up + for execution. This is enabled by default. + --kk All arguments in the form of assignment statements are + placed in the environment for a command, not just those + that precede the command name. + --mm Monitor mode. Job control is enabled. This option is + on by default for interactive shells on systems that + support it (see JJOOBB CCOONNTTRROOLL above). Background pro- + cesses run in a separate process group and a line con- + taining their exit status is printed upon their comple- + tion. + --nn Read commands but do not execute them. This may be used + to check a shell script for syntax errors. This is + ignored by interactive shells. + --oo _o_p_t_i_o_n_-_n_a_m_e + The _o_p_t_i_o_n_-_n_a_m_e can be one of the following: + aalllleexxppoorrtt + Same as --aa. + bbrraacceeeexxppaanndd + Same as --BB. + eemmaaccss Use an emacs-style command line editing inter- + face. This is enabled by default when the shell + is interactive, unless the shell is started with + the ----nnooeeddiittiinngg option. This also affects the + editing interface used for rreeaadd --ee. + eerrrreexxiitt Same as --ee. + eerrrrttrraaccee + Same as --EE. + ffuunnccttrraaccee + Same as --TT. + hhaasshhaallll Same as --hh. + hhiisstteexxppaanndd + Same as --HH. + hhiissttoorryy Enable command history, as described above under + HHIISSTTOORRYY. This option is on by default in inter- + active shells. + iiggnnoorreeeeooff + The effect is as if the shell command + ``IGNOREEOF=10'' had been executed (see SShheellll + VVaarriiaabblleess above). + kkeeyywwoorrdd Same as --kk. + mmoonniittoorr Same as --mm. + nnoocclloobbbbeerr + Same as --CC. + nnooeexxeecc Same as --nn. + nnoogglloobb Same as --ff. + nnoolloogg Currently ignored. + nnoottiiffyy Same as --bb. + nnoouunnsseett Same as --uu. + oonneeccmmdd Same as --tt. + pphhyyssiiccaall + Same as --PP. + ppiippeeffaaiill + If set, the return value of a pipeline is the + value of the last (rightmost) command to exit + with a non-zero status, or zero if all commands + in the pipeline exit successfully. This option + is disabled by default. + ppoossiixx Change the behavior of bbaasshh where the default + operation differs from the POSIX standard to + match the standard (_p_o_s_i_x _m_o_d_e). + pprriivviilleeggeedd + Same as --pp. + vveerrbboossee Same as --vv. + vvii Use a vi-style command line editing interface. + This also affects the editing interface used for + rreeaadd --ee. + xxttrraaccee Same as --xx. + If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, the values of the + current options are printed. If ++oo is supplied with no + _o_p_t_i_o_n_-_n_a_m_e, a series of sseett commands to recreate the + current option settings is displayed on the standard + output. + --pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the $$EENNVV and + $$BBAASSHH__EENNVV files are not processed, shell functions are + not inherited from the environment, and the SSHHEELLLLOOPPTTSS, + BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE variables, if they + appear in the environment, are ignored. If the shell is + started with the effective user (group) id not equal to + the real user (group) id, and the --pp option is not sup- + plied, these actions are taken and the effective user id + is set to the real user id. If the --pp option is sup- + plied at startup, the effective user id is not reset. + Turning this option off causes the effective user and + group ids to be set to the real user and group ids. + --tt Exit after reading and executing one command. + --uu Treat unset variables and parameters other than the spe- + cial parameters "@" and "*" as an error when performing + parameter expansion. If expansion is attempted on an + unset variable or parameter, the shell prints an error + message, and, if not interactive, exits with a non-zero + status. + --vv Print shell input lines as they are read. + --xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee + command, sseelleecctt command, or arithmetic ffoorr command, dis- + play the expanded value of PPSS44, followed by the command + and its expanded arguments or associated word list. + --BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn + above). This is on by default. + --CC If set, bbaasshh does not overwrite an existing file with + the >>, >>&&, and <<>> redirection operators. This may be + overridden when creating output files by using the redi- + rection operator >>|| instead of >>. + --EE If set, any trap on EERRRR is inherited by shell functions, + command substitutions, and commands executed in a sub- + shell environment. The EERRRR trap is normally not inher- + ited in such cases. + --HH Enable !! style history substitution. This option is on + by default when the shell is interactive. + --PP If set, the shell does not follow symbolic links when + executing commands such as ccdd that change the current + working directory. It uses the physical directory + structure instead. By default, bbaasshh follows the logical + chain of directories when performing commands which + change the current directory. + --TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by + shell functions, command substitutions, and commands + executed in a subshell environment. The DDEEBBUUGG and + RREETTUURRNN traps are normally not inherited in such cases. + ---- If no arguments follow this option, then the positional + parameters are unset. Otherwise, the positional parame- + ters are set to the _a_r_gs, even if some of them begin + with a --. + -- Signal the end of options, cause all remaining _a_r_gs to + be assigned to the positional parameters. The --xx and --vv + options are turned off. If there are no _a_r_gs, the posi- + tional parameters remain unchanged. + + The options are off by default unless otherwise noted. Using + + rather than - causes these options to be turned off. The + options can also be specified as arguments to an invocation of + the shell. The current set of options may be found in $$--. The + return status is always true unless an invalid option is encoun- + tered. + + sshhiifftt [_n] + The positional parameters from _n+1 ... are renamed to $$11 ........ + Parameters represented by the numbers $$## down to $$##-_n+1 are + unset. _n must be a non-negative number less than or equal to + $$##. If _n is 0, no parameters are changed. If _n is not given, + it is assumed to be 1. If _n is greater than $$##, the positional + parameters are not changed. The return status is greater than + zero if _n is greater than $$## or less than zero; otherwise 0. + + sshhoopptt [--ppqqssuu] [--oo] [_o_p_t_n_a_m_e ...] + Toggle the values of variables controlling optional shell behav- + ior. With no options, or with the --pp option, a list of all set- + table options is displayed, with an indication of whether or not + each is set. The --pp option causes output to be displayed in a + form that may be reused as input. Other options have the fol- + lowing meanings: + --ss Enable (set) each _o_p_t_n_a_m_e. + --uu Disable (unset) each _o_p_t_n_a_m_e. + --qq Suppresses normal output (quiet mode); the return status + indicates whether the _o_p_t_n_a_m_e is set or unset. If multi- + ple _o_p_t_n_a_m_e arguments are given with --qq, the return sta- + tus is zero if all _o_p_t_n_a_m_e_s are enabled; non-zero other- + wise. + --oo Restricts the values of _o_p_t_n_a_m_e to be those defined for + the --oo option to the sseett builtin. + + If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, the dis- + play is limited to those options which are set or unset, respec- + tively. Unless otherwise noted, the sshhoopptt options are disabled + (unset) by default. + + The return status when listing options is zero if all _o_p_t_n_a_m_e_s + are enabled, non-zero otherwise. When setting or unsetting + options, the return status is zero unless an _o_p_t_n_a_m_e is not a + valid shell option. + + The list of sshhoopptt options is: + + aauuttooccdd If set, a command name that is the name of a directory + is executed as if it were the argument to the ccdd com- + mand. This option is only used by interactive shells. + ccddaabbllee__vvaarrss + If set, an argument to the ccdd builtin command that is + not a directory is assumed to be the name of a variable + whose value is the directory to change to. + ccddssppeellll If set, minor errors in the spelling of a directory com- + ponent in a ccdd command will be corrected. The errors + checked for are transposed characters, a missing charac- + ter, and one character too many. If a correction is + found, the corrected file name is printed, and the com- + mand proceeds. This option is only used by interactive + shells. + cchheecckkhhaasshh + If set, bbaasshh checks that a command found in the hash ta- + ble exists before trying to execute it. If a hashed + command no longer exists, a normal path search is per- + formed. + cchheecckkjjoobbss + If set, bbaasshh lists the status of any stopped and running + jobs before exiting an interactive shell. If any jobs + are running, this causes the exit to be deferred until a + second exit is attempted without an intervening command + (see JJOOBB CCOONNTTRROOLL above). The shell always postpones + exiting if any jobs are stopped. + cchheecckkwwiinnssiizzee + If set, bbaasshh checks the window size after each command + and, if necessary, updates the values of LLIINNEESS and CCOOLL-- + UUMMNNSS. + ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple- + line command in the same history entry. This allows + easy re-editing of multi-line commands. + ccoommppaatt3311 + If set, bbaasshh changes its behavior to that of version 3.1 + with respect to quoted arguments to the conditional com- + mand's =~ operator. + ccoommppaatt3322 + If set, bbaasshh changes its behavior to that of version 3.2 + with respect to locale-specific string comparison when + using the conditional command's < and > operators. + ccoommppaatt4400 + If set, bbaasshh changes its behavior to that of version 4.0 + with respect to locale-specific string comparison when + using the conditional command's < and > operators and + the effect of interrupting a command list. + ddiirrssppeellll + If set, bbaasshh attempts spelling correction on directory + names during word completion if the directory name ini- + tially supplied does not exist. + ddoottgglloobb If set, bbaasshh includes filenames beginning with a `.' in + the results of pathname expansion. + eexxeeccffaaiill + If set, a non-interactive shell will not exit if it can- + not execute the file specified as an argument to the + eexxeecc builtin command. An interactive shell does not + exit if eexxeecc fails. + eexxppaanndd__aalliiaasseess + If set, aliases are expanded as described above under + AALLIIAASSEESS. This option is enabled by default for interac- + tive shells. + eexxttddeebbuugg + If set, behavior intended for use by debuggers is + enabled: + 11.. The --FF option to the ddeeccllaarree builtin displays the + source file name and line number corresponding to + each function name supplied as an argument. + 22.. If the command run by the DDEEBBUUGG trap returns a + non-zero value, the next command is skipped and + not executed. + 33.. If the command run by the DDEEBBUUGG trap returns a + value of 2, and the shell is executing in a sub- + routine (a shell function or a shell script exe- + cuted by the .. or ssoouurrccee builtins), a call to + rreettuurrnn is simulated. + 44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described + in their descriptions above. + 55.. Function tracing is enabled: command substitu- + tion, shell functions, and subshells invoked with + (( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps. + 66.. Error tracing is enabled: command substitution, + shell functions, and subshells invoked with (( + _c_o_m_m_a_n_d )) inherit the EERRRROORR trap. + eexxttgglloobb If set, the extended pattern matching features described + above under PPaatthhnnaammee EExxppaannssiioonn are enabled. + eexxttqquuoottee + If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed + within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double + quotes. This option is enabled by default. + ffaaiillgglloobb + If set, patterns which fail to match filenames during + pathname expansion result in an expansion error. + ffoorrccee__ffiiggnnoorree + If set, the suffixes specified by the FFIIGGNNOORREE shell + variable cause words to be ignored when performing word + completion even if the ignored words are the only possi- + ble completions. See SSHHEELLLL VVAARRIIAABBLLEESS above for a + description of FFIIGGNNOORREE. This option is enabled by + default. + gglloobbssttaarr + If set, the pattern **** used in a pathname expansion con- + text will match a files and zero or more directories and + subdirectories. If the pattern is followed by a //, only + directories and subdirectories match. + ggnnuu__eerrrrffmmtt + If set, shell error messages are written in the standard + GNU error message format. + hhiissttaappppeenndd + If set, the history list is appended to the file named + by the value of the HHIISSTTFFIILLEE variable when the shell + exits, rather than overwriting the file. + hhiissttrreeeeddiitt + If set, and rreeaaddlliinnee is being used, a user is given the + opportunity to re-edit a failed history substitution. + hhiissttvveerriiffyy + If set, and rreeaaddlliinnee is being used, the results of his- + tory substitution are not immediately passed to the + shell parser. Instead, the resulting line is loaded + into the rreeaaddlliinnee editing buffer, allowing further modi- + fication. + hhoossttccoommpplleettee + If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to + perform hostname completion when a word containing a @@ + is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE + above). This is enabled by default. + hhuuppoonneexxiitt + If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter- + active login shell exits. + iinntteerraaccttiivvee__ccoommmmeennttss + If set, allow a word beginning with ## to cause that word + and all remaining characters on that line to be ignored + in an interactive shell (see CCOOMMMMEENNTTSS above). This + option is enabled by default. + lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line + commands are saved to the history with embedded newlines + rather than using semicolon separators where possible. + llooggiinn__sshheellll + The shell sets this option if it is started as a login + shell (see IINNVVOOCCAATTIIOONN above). The value may not be + changed. + mmaaiillwwaarrnn + If set, and a file that bbaasshh is checking for mail has + been accessed since the last time it was checked, the + message ``The mail in _m_a_i_l_f_i_l_e has been read'' is dis- + played. + nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn + If set, and rreeaaddlliinnee is being used, bbaasshh will not + attempt to search the PPAATTHH for possible completions when + completion is attempted on an empty line. + nnooccaasseegglloobb + If set, bbaasshh matches filenames in a case-insensitive + fashion when performing pathname expansion (see PPaatthhnnaammee + EExxppaannssiioonn above). + nnooccaasseemmaattcchh + If set, bbaasshh matches patterns in a case-insensitive + fashion when performing matching while executing ccaassee or + [[[[ conditional commands. + nnuullllgglloobb + If set, bbaasshh allows patterns which match no files (see + PPaatthhnnaammee EExxppaannssiioonn above) to expand to a null string, + rather than themselves. + pprrooggccoommpp + If set, the programmable completion facilities (see PPrroo-- + ggrraammmmaabbllee CCoommpplleettiioonn above) are enabled. This option is + enabled by default. + pprroommppttvvaarrss + If set, prompt strings undergo parameter expansion, com- + mand substitution, arithmetic expansion, and quote + removal after being expanded as described in PPRROOMMPPTTIINNGG + above. This option is enabled by default. + rreessttrriicctteedd__sshheellll + The shell sets this option if it is started in + restricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value + may not be changed. This is not reset when the startup + files are executed, allowing the startup files to dis- + cover whether or not a shell is restricted. + sshhiifftt__vveerrbboossee + If set, the sshhiifftt builtin prints an error message when + the shift count exceeds the number of positional parame- + ters. + ssoouurrcceeppaatthh + If set, the ssoouurrccee (..) builtin uses the value of PPAATTHH to + find the directory containing the file supplied as an + argument. This option is enabled by default. + xxppgg__eecchhoo + If set, the eecchhoo builtin expands backslash-escape + sequences by default. + ssuussppeenndd [--ff] + Suspend the execution of this shell until it receives a SSIIGGCCOONNTT + signal. A login shell cannot be suspended; the --ff option can be + used to override this and force the suspension. The return sta- + tus is 0 unless the shell is a login shell and --ff is not sup- + plied, or if job control is not enabled. + tteesstt _e_x_p_r + [[ _e_x_p_r ]] + Return a status of 0 or 1 depending on the evaluation of the + conditional expression _e_x_p_r. Each operator and operand must be + a separate argument. Expressions are composed of the primaries + described above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. tteesstt does not + accept any options, nor does it accept and ignore an argument of + ---- as signifying the end of options. + + Expressions may be combined using the following operators, + listed in decreasing order of precedence. The evaluation + depends on the number of arguments; see below. + !! _e_x_p_r True if _e_x_p_r is false. + (( _e_x_p_r )) + Returns the value of _e_x_p_r. This may be used to override + the normal precedence of operators. + _e_x_p_r_1 -aa _e_x_p_r_2 + True if both _e_x_p_r_1 and _e_x_p_r_2 are true. + _e_x_p_r_1 -oo _e_x_p_r_2 + True if either _e_x_p_r_1 or _e_x_p_r_2 is true. + + tteesstt and [[ evaluate conditional expressions using a set of rules + based on the number of arguments. + + 0 arguments + The expression is false. + 1 argument + The expression is true if and only if the argument is not + null. + 2 arguments + If the first argument is !!, the expression is true if and + only if the second argument is null. If the first argu- + ment is one of the unary conditional operators listed + above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the expression is + true if the unary test is true. If the first argument is + not a valid unary conditional operator, the expression is + false. + 3 arguments + If the second argument is one of the binary conditional + operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the + result of the expression is the result of the binary test + using the first and third arguments as operands. The --aa + and --oo operators are considered binary operators when + there are three arguments. If the first argument is !!, + the value is the negation of the two-argument test using + the second and third arguments. If the first argument is + exactly (( and the third argument is exactly )), the result + is the one-argument test of the second argument. Other- + wise, the expression is false. + 4 arguments + If the first argument is !!, the result is the negation of + the three-argument expression composed of the remaining + arguments. Otherwise, the expression is parsed and eval- + uated according to precedence using the rules listed + above. + 5 or more arguments + The expression is parsed and evaluated according to + precedence using the rules listed above. + + ttiimmeess Print the accumulated user and system times for the shell and + for processes run from the shell. The return status is 0. + + ttrraapp [--llpp] [[_a_r_g] _s_i_g_s_p_e_c ...] + The command _a_r_g is to be read and executed when the shell + receives signal(s) _s_i_g_s_p_e_c. If _a_r_g is absent (and there is a + single _s_i_g_s_p_e_c) or --, each specified signal is reset to its + original disposition (the value it had upon entrance to the + shell). If _a_r_g is the null string the signal specified by each + _s_i_g_s_p_e_c is ignored by the shell and by the commands it invokes. + If _a_r_g is not present and --pp has been supplied, then the trap + commands associated with each _s_i_g_s_p_e_c are displayed. If no + arguments are supplied or if only --pp is given, ttrraapp prints the + list of commands associated with each signal. The --ll option + causes the shell to print a list of signal names and their cor- + responding numbers. Each _s_i_g_s_p_e_c is either a signal name + defined in <_s_i_g_n_a_l_._h>, or a signal number. Signal names are + case insensitive and the SIG prefix is optional. + + If a _s_i_g_s_p_e_c is EEXXIITT (0) the command _a_r_g is executed on exit + from the shell. If a _s_i_g_s_p_e_c is DDEEBBUUGG, the command _a_r_g is exe- + cuted before every _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command, + _s_e_l_e_c_t command, every arithmetic _f_o_r command, and before the + first command executes in a shell function (see SSHHEELLLL GGRRAAMMMMAARR + above). Refer to the description of the eexxttddeebbuugg option to the + sshhoopptt builtin for details of its effect on the DDEEBBUUGG trap. If a + _s_i_g_s_p_e_c is RREETTUURRNN, the command _a_r_g is executed each time a shell + function or a script executed with the .. or ssoouurrccee builtins fin- + ishes executing. + + If a _s_i_g_s_p_e_c is EERRRR, the command _a_r_g is executed whenever a sim- + ple command has a non-zero exit status, subject to the following + conditions. The EERRRR trap is not executed if the failed command + is part of the command list immediately following a wwhhiillee or + uunnttiill keyword, part of the test in an _i_f statement, part of a + command executed in a &&&& or |||| list, or if the command's return + value is being inverted via !!. These are the same conditions + obeyed by the eerrrreexxiitt option. + + Signals ignored upon entry to the shell cannot be trapped or + reset. Trapped signals that are not being ignored are reset to + their original values in a subshell or subshell environment when + one is created. The return status is false if any _s_i_g_s_p_e_c is + invalid; otherwise ttrraapp returns true. + + ttyyppee [--aaffttppPP] _n_a_m_e [_n_a_m_e ...] + With no options, indicate how each _n_a_m_e would be interpreted if + used as a command name. If the --tt option is used, ttyyppee prints a + string which is one of _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or + _f_i_l_e if _n_a_m_e is an alias, shell reserved word, function, + builtin, or disk file, respectively. If the _n_a_m_e is not found, + then nothing is printed, and an exit status of false is + returned. If the --pp option is used, ttyyppee either returns the + name of the disk file that would be executed if _n_a_m_e were speci- + fied as a command name, or nothing if ``type -t name'' would not + return _f_i_l_e. The --PP option forces a PPAATTHH search for each _n_a_m_e, + even if ``type -t name'' would not return _f_i_l_e. If a command is + hashed, --pp and --PP print the hashed value, not necessarily the + file that appears first in PPAATTHH. If the --aa option is used, ttyyppee + prints all of the places that contain an executable named _n_a_m_e. + This includes aliases and functions, if and only if the --pp + option is not also used. The table of hashed commands is not + consulted when using --aa. The --ff option suppresses shell func- + tion lookup, as with the ccoommmmaanndd builtin. ttyyppee returns true if + all of the arguments are found, false if any are not found. + + uulliimmiitt [--HHSSTTaabbccddeeffiillmmnnppqqrrssttuuvvxx [_l_i_m_i_t]] + Provides control over the resources available to the shell and + to processes started by it, on systems that allow such control. + The --HH and --SS options specify that the hard or soft limit is set + for the given resource. A hard limit cannot be increased by a + non-root user once it is set; a soft limit may be increased up + to the value of the hard limit. If neither --HH nor --SS is speci- + fied, both the soft and hard limits are set. The value of _l_i_m_i_t + can be a number in the unit specified for the resource or one of + the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, which stand for the + current hard limit, the current soft limit, and no limit, + respectively. If _l_i_m_i_t is omitted, the current value of the + soft limit of the resource is printed, unless the --HH option is + given. When more than one resource is specified, the limit name + and unit are printed before the value. Other options are inter- + preted as follows: + --aa All current limits are reported + --bb The maximum socket buffer size + --cc The maximum size of core files created + --dd The maximum size of a process's data segment + --ee The maximum scheduling priority ("nice") + --ff The maximum size of files written by the shell and its + children + --ii The maximum number of pending signals + --ll The maximum size that may be locked into memory + --mm The maximum resident set size (many systems do not honor + this limit) + --nn The maximum number of open file descriptors (most systems + do not allow this value to be set) + --pp The pipe size in 512-byte blocks (this may not be set) + --qq The maximum number of bytes in POSIX message queues + --rr The maximum real-time scheduling priority + --ss The maximum stack size + --tt The maximum amount of cpu time in seconds + --uu The maximum number of processes available to a single + user + --vv The maximum amount of virtual memory available to the + shell + --xx The maximum number of file locks + --TT The maximum number of threads + + If _l_i_m_i_t is given, it is the new value of the specified resource + (the --aa option is display only). If no option is given, then --ff + is assumed. Values are in 1024-byte increments, except for --tt, + which is in seconds, --pp, which is in units of 512-byte blocks, + and --TT, --bb, --nn, and --uu, which are unscaled values. The return + status is 0 unless an invalid option or argument is supplied, or + an error occurs while setting a new limit. + + uummaasskk [--pp] [--SS] [_m_o_d_e] + The user file-creation mask is set to _m_o_d_e. If _m_o_d_e begins with + a digit, it is interpreted as an octal number; otherwise it is + interpreted as a symbolic mode mask similar to that accepted by + _c_h_m_o_d(1). If _m_o_d_e is omitted, the current value of the mask is + printed. The --SS option causes the mask to be printed in sym- + bolic form; the default output is an octal number. If the --pp + option is supplied, and _m_o_d_e is omitted, the output is in a form + that may be reused as input. The return status is 0 if the mode + was successfully changed or if no _m_o_d_e argument was supplied, + and false otherwise. + + uunnaalliiaass [-aa] [_n_a_m_e ...] + Remove each _n_a_m_e from the list of defined aliases. If --aa is + supplied, all alias definitions are removed. The return value + is true unless a supplied _n_a_m_e is not a defined alias. + + uunnsseett [-ffvv] [_n_a_m_e ...] + For each _n_a_m_e, remove the corresponding variable or function. + If no options are supplied, or the --vv option is given, each _n_a_m_e + refers to a shell variable. Read-only variables may not be + unset. If --ff is specified, each _n_a_m_e refers to a shell func- + tion, and the function definition is removed. Each unset vari- + able or function is removed from the environment passed to sub- + sequent commands. If any of CCOOMMPP__WWOORRDDBBRREEAAKKSS, RRAANNDDOOMM, SSEECCOONNDDSS, + LLIINNEENNOO, HHIISSTTCCMMDD, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, or DDIIRRSSTTAACCKK are unset, they + lose their special properties, even if they are subsequently + reset. The exit status is true unless a _n_a_m_e is readonly. + + wwaaiitt [_n _._._.] + Wait for each specified process and return its termination sta- + tus. Each _n may be a process ID or a job specification; if a + job spec is given, all processes in that job's pipeline are + waited for. If _n is not given, all currently active child pro- + cesses are waited for, and the return status is zero. If _n + specifies a non-existent process or job, the return status is + 127. Otherwise, the return status is the exit status of the + last process or job waited for. + +RREESSTTRRIICCTTEEDD SSHHEELLLL + If bbaasshh is started with the name rrbbaasshh, or the --rr option is supplied at + invocation, the shell becomes restricted. A restricted shell is used + to set up an environment more controlled than the standard shell. It + behaves identically to bbaasshh with the exception that the following are + disallowed or not performed: + + +o changing directories with ccdd + + +o setting or unsetting the values of SSHHEELLLL, PPAATTHH, EENNVV, or BBAASSHH__EENNVV + + +o specifying command names containing // + + +o specifying a file name containing a // as an argument to the .. + builtin command + + +o Specifying a filename containing a slash as an argument to the + --pp option to the hhaasshh builtin command + + +o importing function definitions from the shell environment at + startup + + +o parsing the value of SSHHEELLLLOOPPTTSS from the shell environment at + startup + + +o redirecting output using the >, >|, <>, >&, &>, and >> redirect- + ion operators + + +o using the eexxeecc builtin command to replace the shell with another + command + + +o adding or deleting builtin commands with the --ff and --dd options + to the eennaabbllee builtin command + + +o Using the eennaabbllee builtin command to enable disabled shell + builtins + + +o specifying the --pp option to the ccoommmmaanndd builtin command + + +o turning off restricted mode with sseett ++rr or sseett ++oo rreessttrriicctteedd. + + These restrictions are enforced after any startup files are read. + + When a command that is found to be a shell script is executed (see CCOOMM-- + MMAANNDD EEXXEECCUUTTIIOONN above), rrbbaasshh turns off any restrictions in the shell + spawned to execute the script. + +SSEEEE AALLSSOO + _B_a_s_h _R_e_f_e_r_e_n_c_e _M_a_n_u_a_l, Brian Fox and Chet Ramey + _T_h_e _G_n_u _R_e_a_d_l_i_n_e _L_i_b_r_a_r_y, Brian Fox and Chet Ramey + _T_h_e _G_n_u _H_i_s_t_o_r_y _L_i_b_r_a_r_y, Brian Fox and Chet Ramey + _P_o_r_t_a_b_l_e _O_p_e_r_a_t_i_n_g _S_y_s_t_e_m _I_n_t_e_r_f_a_c_e _(_P_O_S_I_X_) _P_a_r_t _2_: _S_h_e_l_l _a_n_d _U_t_i_l_i_- + _t_i_e_s, IEEE + _s_h(1), _k_s_h(1), _c_s_h(1) + _e_m_a_c_s(1), _v_i(1) + _r_e_a_d_l_i_n_e(3) + +FFIILLEESS + _/_b_i_n_/_b_a_s_h + The bbaasshh executable + _/_e_t_c_/_p_r_o_f_i_l_e + The systemwide initialization file, executed for login shells + _~_/_._b_a_s_h___p_r_o_f_i_l_e + The personal initialization file, executed for login shells + _~_/_._b_a_s_h_r_c + The individual per-interactive-shell startup file + _~_/_._b_a_s_h___l_o_g_o_u_t + The individual login shell cleanup file, executed when a login + shell exits + _~_/_._i_n_p_u_t_r_c + Individual _r_e_a_d_l_i_n_e initialization file + +AAUUTTHHOORRSS + Brian Fox, Free Software Foundation + bfox@gnu.org + + Chet Ramey, Case Western Reserve University + chet.ramey@case.edu + +BBUUGG RREEPPOORRTTSS + If you find a bug in bbaasshh,, you should report it. But first, you should + make sure that it really is a bug, and that it appears in the latest + version of bbaasshh. The latest version is always available from + _f_t_p_:_/_/_f_t_p_._g_n_u_._o_r_g_/_p_u_b_/_b_a_s_h_/. + + Once you have determined that a bug actually exists, use the _b_a_s_h_b_u_g + command to submit a bug report. If you have a fix, you are encouraged + to mail that as well! Suggestions and `philosophical' bug reports may + be mailed to _b_u_g_-_b_a_s_h_@_g_n_u_._o_r_g or posted to the Usenet newsgroup + ggnnuu..bbaasshh..bbuugg. + + ALL bug reports should include: + + The version number of bbaasshh + The hardware and operating system + The compiler used to compile + A description of the bug behaviour + A short script or `recipe' which exercises the bug + + _b_a_s_h_b_u_g inserts the first three items automatically into the template + it provides for filing a bug report. + + Comments and bug reports concerning this manual page should be directed + to _c_h_e_t_@_p_o_._c_w_r_u_._e_d_u. + +BBUUGGSS + It's too big and too slow. + + There are some subtle differences between bbaasshh and traditional versions + of sshh, mostly because of the PPOOSSIIXX specification. + + Aliases are confusing in some uses. + + Shell builtin commands and functions are not stoppable/restartable. + + Compound commands and command sequences of the form `a ; b ; c' are not + handled gracefully when process suspension is attempted. When a + process is stopped, the shell immediately executes the next command in + the sequence. It suffices to place the sequence of commands between + parentheses to force it into a subshell, which may be stopped as a + unit. + + Array variables may not (yet) be exported. + + There may be only one active coprocess at a time. + + + +GNU Bash-4.1 2009 December 29 BASH(1) |