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Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 96 |
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@@ -1,3 +1,99 @@ +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. + +------------------------------------------------------------------------------- This is a terse description of the new features added to bash-4.1 since the release of bash-4.0. As always, the manual page (doc/bash.1) is the place to look for complete descriptions. |