Introduction ============ The first public release of bash-4.2 is now available with the URLs
ftp://ftp.cwru.edu/pub/bash/bash-4.2.tar.gz ftp://ftp.gnu.org/pub/gnu/bash/bash-4.2.tar.gz and from the usual GNU mirror sites. This tar file includes the formatted documentation (postscript, dvi, html, and nroffed versions of the manual pages). Diffs from bash-4.1 are not available. Please use `bashbug' to report bugs with this version. It is built and installed at the same time as bash. Installation ============ Please read the README file first. Installation instructions are provided in the INSTALL file. New Features ============ This is the second revision to the fourth major release of bash. This release fixes several outstanding bugs in bash-4.1 and introduces several new features. The most notable new features are \u and \U unicode character escapes for the echo and printf builtins and $'...' quoting, a new mechanism to declare variables with attributes in the global scope from a shell function, and new word expansion features. There are also a number of changes to accommodate recent Posix shell interpretations, changing the bash posix-mode behavior to align with the newly-intepreted standard. Read the file NEWS in the bash-4.2 distribution for a complete description of the new features. A copy of the relevant portions is included below. Changes have been made to the Readline library being released at the same time as bash-4.2, readline-6.2, so that Bash can be linked against an already-installed Readline library rather than the private version in lib/readline. Only readline-6.0 and later versions are able to provide all of the symbols that bash-4.2 requires; earlier versions of the Readline library will not work correctly. A complete list of changes between bash-4.1 and bash-4.2 is available in the file CHANGES; the complete list is too large to include in this message. Readline ======== Also available is a new release of the standalone Readline library, version 6.2, with its own configuration scripts and Makefiles. It can be retrieved with the URLs ftp://ftp.cwru.edu/pub/bash/readline-6.2.tar.gz ftp://ftp.gnu.org/pub/gnu/readline/readline-6.2.tar.gz and from the usual GNU mirror sites. Diffs from readline-6.1 are not available. The formatted Readline documentation is included in the readline distribution tar file. A separate announcement listing the changes in Readline is being distributed. As always, thanks for your help. Chet +========== NEWS ==========+ This is a terse description of the new features added to bash-4.2 since the release of bash-4.1. As always, the manual page (doc/bash.1) is the place to look for complete descriptions. 1. New Features in Bash a. `exec -a foo' now sets $0 to `foo' in an executable shell script without a leading #!. b. Subshells begun to execute command substitutions or run shell functions or builtins in subshells do not reset trap strings until a new trap is specified. This allows $(trap) to display the caller's traps and the trap strings to persist until a new trap is set. c. `trap -p' will now show signals ignored at shell startup, though their disposition still cannot be modified. d. $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences. e. declare/typeset has a new `-g' option, which creates variables in the global scope even when run in a shell function. f. test/[/[[ have a new -v variable unary operator, which returns success if `variable' has been set. g. Posix parsing changes to allow `! time command' and multiple consecutive instances of `!' (which toggle) and `time' (which have no cumulative effect). h. Posix change to allow `time' as a command by itself to print the elapsed user, system, and real times for the shell and its children. j. $((...)) is always parsed as an arithmetic expansion first, instead of as a potential nested command substitution, as Posix requires. k. A new FUNCNEST variable to allow the user to control the maximum shell function nesting (recursive execution) level. l. The mapfile builtin now supplies a third argument to the callback command: the line about to be assigned to the supplied array index. m. The printf builtin has a new %(fmt)T specifier, which allows time values to use strftime-like formatting. n. There is a new `compat41' shell option. o. The cd builtin has a new Posix-mandated `-e' option. p. Negative subscripts to indexed arrays, previously errors, now are treated as offsets from the maximum assigned index + 1. q. Negative length specifications in the ${var:offset:length} expansion, previously errors, are now treated as offsets from the end of the variable. r. Parsing change to allow `time -p --'. s. Posix-mode parsing change to not recognize `time' as a keyword if the following token begins with a `-'. This means no more Posix-mode `time -p'. Posix interpretation 267. t. There is a new `lastpipe' shell option that runs the last command of a pipeline in the current shell context. The lastpipe option has no effect if job control is enabled. u. History expansion no longer expands the `$!' variable expansion. v. Posix mode shells no longer exit if a variable assignment error occurs with an assignment preceding a command that is not a special builtin. w. Non-interactive mode shells exit if -u is enabled and an attempt is made to use an unset variable with the % or # expansions, the `//', `^', or `,' expansions, or the parameter length expansion. x. Posix-mode shells use the argument passed to `.' as-is if a $PATH search fails, effectively searching the current directory. Posix-2008 change. 2. New Features in Readline a. The history library does not try to write the history filename in the current directory if $HOME is unset. This closes a potential security problem if the application does not specify a history filename. b. New bindable variable `completion-display-width' to set the number of columns used when displaying completions. c. New bindable variable `completion-case-map' to cause case-insensitive completion to treat `-' and `_' as identical. d. There are new bindable vi-mode command names to avoid readline's case- insensitive matching not allowing them to be bound separately. e. New bindable variable `menu-complete-display-prefix' causes the menu completion code to display the common prefix of the possible completions before cycling through the list, instead of after. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/
