diff options
Diffstat (limited to 'COMPAT')
| -rw-r--r-- | COMPAT | 104 |
1 files changed, 98 insertions, 6 deletions
@@ -1,10 +1,12 @@ +Compatibility with previous versions +==================================== + 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. +bash-4.1, and the previous widely-available versions, bash-2.x (which is +still the `standard' version for a few Linux distributions) and bash-3.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.) +version and versions 2.0 and above. 1. Bash uses a new quoting syntax, $"...", to do locale-specific string translation. Users who have relied on the (undocumented) @@ -271,5 +273,95 @@ bash-2.0 were significant.) 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. +33. Bash-3.2 adopts the convention used by other string and pattern matching + operators for the `[[' compound command, and matches any quoted portion + of the right-hand-side argument to the =~ operator as a string rather + than a regular expression. + +34. Bash-4.0 allows the behavior in the previous item to be modified using + the notion of a shell `compatibility level'. If the compat31 shopt + option is set, quoting the pattern has no special effect. + +35. Bash-3.2 (patched) and Bash-4.0 fix a bug that leaves the shell in an + inconsistent internal state following an assignment error. One of the + changes means that compound commands or { ... } grouping commands are + aborted under some circumstances in which they previously were not. + This is what Posix specifies. + +36. Bash-4.0 now allows process substitution constructs to pass unchanged + through brace expansion, so any expansion of the contents will have to be + separately specified, and each process subsitution will have to be + separately entered. + +37. Bash-4.0 now allows SIGCHLD to interrupt the wait builtin, as Posix + specifies, so the SIGCHLD trap is no longer always invoked once per + exiting child if you are using `wait' to wait for all children. + +38. Since bash-4.0 now follows Posix rules for finding the closing delimiter + of a $() command substitution, it will not behave as previous versions + did, but will catch more syntax and parsing errors before spawning a + subshell to evaluate the command substitution. + +39. The programmable completion code uses the same set of delimiting characters + as readline when breaking the command line into words, rather than the + set of shell metacharacters, so programmable completion and readline + should be more consistent. + +40. When the read builtin times out, it attempts to assign any input read to + specified variables, which also causes variables to be set to the empty + string if there is not enough input. Previous versions discarded the + characters read. + +41. Beginning with bash-4.0, when one of the commands in a pipeline is killed + by a SIGINT while executing a command list, the shell acts as if it + received the interrupt. This can be disabled by setting the compat31 or + compat32 shell options. + +42. Bash-4.0 changes the handling of the set -e option so that the shell exits + if a pipeline fails (and not just if the last command in the failing + pipeline is a simple command). This is not as Posix specifies. There is + work underway to update this portion of the standard; the bash-4.0 + behavior attempts to capture the consensus at the time of release. + +43. Bash-4.0 fixes a Posix mode bug that caused the . (source) builtin to + search the current directory for its filename argument, even if "." is + not in $PATH. Posix says that the shell shouldn't look in $PWD in this + case. + +44. Bash-4.1 uses the current locale when comparing strings using the < and + > operators to the `[[' command. This can be reverted to the previous + behavior by setting one of the `compatNN' shopt options. + +Shell Compatibility Level +========================= + +Bash-4.0 introduced the concept of a `shell compatibility level', specified +as a set of options to the shopt builtin (compat31, compat32, compat40 at +this writing). There is only one current compatibility level -- each +option is mutually exclusive. This list does not mention behavior that is +standard for a particular version (e.g., setting compat32 means that quoting +the rhs of the regexp matching operator quotes special regexp characters in +the word, which is default behavior in bash-3.2 and above). + +compat31 set + - the < and > operators to the [[ command do not consider the current + locale when comparing strings + - quoting the rhs of the regexp matching operator (=~) has no + special effect + +compat32 set + - the < and > operators to the [[ command do not consider the current + locale when comparing strings + +compat40 set + - the < and > operators to the [[ command do not consider the current + locale when comparing strings + - interrupting a command list such as "a ; b ; c" causes the execution + of the entire list to be aborted + +------------------------------------------------------------------------------- + +Copying and distribution of this file, with or without modification, +are permitted in any medium without royalty provided the copyright +notice and this notice are preserved. This file is offered as-is, +without any warranty. |