diff options
Diffstat (limited to 'COMPAT')
| -rw-r--r-- | COMPAT | 64 |
1 files changed, 49 insertions, 15 deletions
@@ -2,11 +2,13 @@ Compatibility with previous versions ==================================== This document details the incompatibilities between this version of bash, -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. +bash-4.3, and the previous widely-available versions, bash-3.x (which is +still the `standard' version for Mac OS X), 4.0/4.1 (which are still +standard on a few Linux distributions), and bash-4.2, the current +widely-available version. These were discovered by users of bash-2.x +through 4.x, so this list is not comprehensive. Some of these +incompatibilities occur between the current 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) @@ -334,30 +336,58 @@ version and versions 2.0 and above. behavior (ASCII collating and strcmp(3)) by setting one of the `compatNN' shopt options, where NN is less than 41. -45. Command substitutions now remove the caller's trap strings when trap is +45. Bash-4.1 conforms to the current Posix specification for `set -u': + expansions of $@ and $* when there are no positional parameters do not + cause the shell to exit. + +46. Bash-4.1 implements the current Posix specification for `set -e' and + exits when any command fails, not just a simple command or pipeline. + +47. Command substitutions now remove the caller's trap strings when trap is run to set a new trap in the subshell. Previous to bash-4.2, the old trap strings persisted even though the actual signal handlers were reset. -46. When in Posix mode, a single quote is not treated specially in a +48. When in Posix mode, a single quote is not treated specially in a double-quoted ${...} expansion, unless the expansion operator is # or % or the new `//', `^', or `,' expansions. In particular, it does not define a new quoting context. This is from Posix interpretation 221. -47. Posix mode shells no longer exit if a variable assignment error occurs +49. Posix mode shells no longer exit if a variable assignment error occurs with an assignment preceding a command that is not a special builtin. +50. Bash-4.2 attempts to preserve what the user typed when performing word + completion, instead of, for instance, expanding shell variable + references to their value. + +51. When in Posix mode, bash-4.2 exits if the filename supplied as an argument + to `.' is not found and the shell is not interactive. + +52. When compiled for strict Posix compatibility, bash-4.3 does not enable + history expansion by default in interactive shells, since it results in + a non-conforming environment. + +53. Bash-4.3 runs the replacement string in the pattern substitution word + expansion through quote removal. The code already treats quote + characters in the replacement string as special; if it treats them as + special, then quote removal should remove them. 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, and -compat41 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). +as a set of options to the shopt builtin (compat31, compat32, compat40, +compat41, and compat42 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). + +Bash-4.3 introduces a new shell variable: BASH_COMPAT. The value assigned +to this variable (a decimal version number like 4.2, or an integer +corresponding to the compatNN option, like 42) determines the compatibility +level. compat31 set - the < and > operators to the [[ command do not consider the current @@ -378,11 +408,15 @@ compat40 set compat41 set - interrupting a command list such as "a ; b ; c" causes the execution - of the entire list to be aborted (in versions before bash-4.0, + of the entire list to be aborted (in versions before bash-4.1, interrupting one command in a list caused the next to be executed) - when in posix mode, single quotes in the `word' portion of a double-quoted parameter expansion define a new quoting context and are treated specially + +compat42 set + - the replacement string in double-quoted pattern substitution is not + run through quote removal, as in previous versions ------------------------------------------------------------------------------- Copying and distribution of this file, with or without modification, |