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Diffstat (limited to 'COMPAT')
| -rw-r--r-- | COMPAT | 120 |
1 files changed, 85 insertions, 35 deletions
@@ -1,10 +1,10 @@ -This document details the incompatibilites between this version of bash, -bash-3.1, and a previous widely-available version, bash-1.14 (which -is still the `standard' version for a few Linux distributions). These -were discovered by users of bash-2.x and 3.x, so this list is not -comprehensive. Some of these incompatibilities occur between the current -version and versions 2.0 and above. (The differences between bash-1.14 -and bash-2.0 were significant.) +This document details the incompatibilities between this version of bash, +bash-3.2, and the previous widely-available versions, bash-1.14 (which is +still the `standard' version for a few Linux distributions) and bash-2.x. +These were discovered by users of bash-2.x and 3.x, so this list is not +comprehensive. Some of these incompatibilities occur between the current +version and versions 2.0 and above. (The differences between bash-1.14 and +bash-2.0 were significant.) 1. Bash uses a new quoting syntax, $"...", to do locale-specific string translation. Users who have relied on the (undocumented) @@ -184,42 +184,92 @@ and bash-2.0 were significant.) with `z' and still allow individual users to change the collation order. Users may put the above command into their own profiles as well, of course. -14. Bash versions up to 1.14.7 included an undocumented `-l' operator to - the `test/[' builtin. It was a unary operator that expanded to the - length of its string argument. This let you do things like +14. Bash versions up to 1.14.7 included an undocumented `-l' operator to + the `test/[' builtin. It was a unary operator that expanded to the + length of its string argument. This let you do things like test -l $variable -lt 20 - for example. + for example. - This was included for backwards compatibility with old versions of the - Bourne shell, which did not provide an easy way to obtain the length of - the value of a shell variable. + This was included for backwards compatibility with old versions of the + Bourne shell, which did not provide an easy way to obtain the length of + the value of a shell variable. - This operator is not part of the POSIX standard, because one can (and - should) use ${#variable} to get the length of a variable's value. - Bash-2.x does not support it. + This operator is not part of the POSIX standard, because one can (and + should) use ${#variable} to get the length of a variable's value. + Bash-2.x does not support it. -15. Bash no longer auto-exports the HOME, PATH, SHELL, TERM, HOSTNAME, - HOSTTYPE, MACHTYPE, or OSTYPE variables. +15. Bash no longer auto-exports the HOME, PATH, SHELL, TERM, HOSTNAME, + HOSTTYPE, MACHTYPE, or OSTYPE variables. If they appear in the initial + environment, the export attribute will be set, but if bash provides a + default value, they will remain local to the current shell. -16. Bash no longer initializes the FUNCNAME, GROUPS, or DIRSTACK variables - to have special behavior if they appear in the initial environment. +16. Bash no longer initializes the FUNCNAME, GROUPS, or DIRSTACK variables + to have special behavior if they appear in the initial environment. -17. Bash no longer removes the export attribute from the SSH_CLIENT or - SSH2_CLIENT variables, and no longer attempts to discover whether or - not it has been invoked by sshd in order to run the startup files. +17. Bash no longer removes the export attribute from the SSH_CLIENT or + SSH2_CLIENT variables, and no longer attempts to discover whether or + not it has been invoked by sshd in order to run the startup files. -18. Bash no longer requires that the body of a function be a group command; - any compound command is accepted. +18. Bash no longer requires that the body of a function be a group command; + any compound command is accepted. -19. As of bash-3.0, the pattern substitution operators no longer perform - quote removal on the pattern before attempting the match. This is the - way the pattern removal functions behave, and is more consistent. +19. As of bash-3.0, the pattern substitution operators no longer perform + quote removal on the pattern before attempting the match. This is the + way the pattern removal functions behave, and is more consistent. -20. After bash-3.0 was released, I reimplemented tilde expansion, incorporating - it into the mainline word expansion code. This fixes the bug that caused - the results of tilde expansion to be re-expanded. There is one - incompatibility: a ${paramOPword} expansion within double quotes will not - perform tilde expansion on WORD. This is consistent with the other - expansions, and what POSIX specifies. +20. After bash-3.0 was released, I reimplemented tilde expansion, incorporating + it into the mainline word expansion code. This fixes the bug that caused + the results of tilde expansion to be re-expanded. There is one + incompatibility: a ${paramOPword} expansion within double quotes will not + perform tilde expansion on WORD. This is consistent with the other + expansions, and what POSIX specifies. + +21. A number of variables have the integer attribute by default, so the += + assignment operator returns expected results: RANDOM, LINENO, MAILCHECK, + HISTCMD, OPTIND. + +22. Bash-3.x is much stricter about $LINENO correctly reflecting the line + number in a script; assignments to LINENO have little effect. + +23. By default, readline binds the terminal special characters to their + readline equivalents. As of bash-3.1/readline-5.1, this is optional and + controlled by the bind-tty-special-chars readline variable. + +24. The \W prompt string expansion abbreviates $HOME as `~'. The previous + behavior is available with ${PWD##/*/}. + +25. The arithmetic exponentiation operator is right-associative as of bash-3.1. + +26. The rules concerning valid alias names are stricter, as per POSIX.2. + +27. The Readline key binding functions now obey the convert-meta setting active + when the binding takes place, as the dispatch code does when characters + are read and processed. + +28. The historical behavior of `trap' reverting signal disposition to the + original handling in the absence of a valid first argument is implemented + only if the first argument is a valid signal number. + +29. In versions of bash after 3.1, the ${parameter//pattern/replacement} + expansion does not interpret `%' or `#' specially. Those anchors don't + have any real meaning when replacing every match. + +30. Beginning with bash-3.1, the combination of posix mode and enabling the + `xpg_echo' option causes echo to ignore all options, not looking for `-n' + +31. Beginning with bash-3.2, bash follows the Bourne-shell-style (and POSIX- + style) rules for parsing the contents of old-style backquoted command + substitutions. Previous versions of bash attempted to recursively parse + embedded quoted strings and shell constructs; bash-3.2 uses strict POSIX + rules to find the closing backquote and simply passes the contents of the + command substitution to a subshell for parsing and execution. + +32. Beginning with bash-3.2, bash uses access(2) when executing primaries for + the test builtin and the [[ compound command, rather than looking at the + file permission bits obtained with stat(2). This obeys restrictions of + the file system (e.g., read-only or noexec mounts) not available via stat. + +33. Beginning with bash-3.1/readline-5.1, the readline key binding code obeys + the current setting of the `convert-meta' variable. |