+This is a terse description of the new features added to bash-4.3 since
+the release of bash-4.2. As always, the manual page (doc/bash.1) is
+the place to look for complete descriptions.
+
+1. New Features in Bash
+
+a. The `helptopic' completion action now maps to all the help topics, not just
+ the shell builtins.
+
+b. The `help' builtin no longer does prefix substring matching first, so
+ `help read' does not match `readonly', but will do it if exact string
+ matching fails.
+
+c. The shell can be compiled to not display a message about processes that
+ terminate due to SIGTERM.
+
+d. Non-interactive shells now react to the setting of checkwinsize and set
+ LINES and COLUMNS after a foreground job exits.
+
+e. There is a new shell option, `globasciiranges', which, when set to on,
+ forces globbing range comparisons to use character ordering as if they
+ were run in the C locale.
+
+f. There is a new shell option, `direxpand', which makes filename completion
+ expand variables in directory names in the way bash-4.1 did.
+
+g. In Posix mode, the `command' builtin does not change whether or not a
+ builtin it shadows is treated as an assignment builtin.
+
+h. The `return' and `exit' builtins accept negative exit status arguments.
+
+i. The word completion code checks whether or not a filename containing a
+ shell variable expands to a directory name and appends `/' to the word
+ as appropriate. The same code expands shell variables in command names
+ when performing command completion.
+
+j. In Posix mode, it is now an error to attempt to define a shell function
+ with the same name as a Posix special builtin.
+
+k. When compiled for strict Posix conformance, history expansion is disabled
+ by default.
+
+l. The history expansion character (!) does not cause history expansion when
+ followed by the closing quote in a double-quoted string.
+
+m. `complete' and its siblings compgen/compopt now takes a new `-o noquote'
+ option to inhibit quoting of the completions.
+
+n. Setting HISTSIZE to a value less than zero causes the history list to be
+ unlimited (setting it 0 zero disables the history list).
+
+o. Setting HISTFILESIZE to a value less than zero causes the history file size
+ to be unlimited (setting it to 0 causes the history file to be truncated
+ to zero size).
+
+p. The `read' builtin now skips NUL bytes in the input.
+
+q. There is a new `bind -X' option to print all key sequences bound to Unix
+ commands.
+
+r. When in Posix mode, `read' is interruptible by a trapped signal. After
+ running the trap handler, read returns 128+signal and throws away any
+ partially-read input.
+
+s. The command completion code skips whitespace and assignment statements
+ before looking for the command name word to be completed.
+
+t. The build process has a new mechanism for constructing separate help files
+ that better reflects the current set of compilation options.
+
+u. The -nt and -ot options to test now work with files with nanosecond
+ timestamp resolution.
+
+v. The shell saves the command history in any shell for which history is
+ enabled and HISTFILE is set, not just interactive shells.
+
+w. The shell has `nameref' variables and new -n(/+n) options to declare and
+ unset to use them, and a `test -R' option to test for them.
+
+x. The shell now allows assigning, referencing, and unsetting elements of
+ indexed arrays using negative subscripts (a[-1]=2, echo ${a[-1]}) which
+ count back from the last element of the array.
+
+y. The {x}<word redirection feature now allows words like {array[ind]} and
+ can use variables with special meanings to the shell (e.g., BASH_XTRACEFD).
+
+z. There is a new CHILD_MAX special shell variable; its value controls the
+ number of exited child statues the shell remembers.
+
+aa. There is a new configuration option (--enable-direxpand-default) that
+ causes the `direxpand' shell option to be enabled by default.
+
+bb. Bash does not do anything special to ensure that the file descriptor
+ assigned to X in {x}<foo remains open after the block containing it
+ completes.
+
+cc. The `wait' builtin has a new `-n' option to wait for the next child to
+ change status.
+
+dd. The `printf' %(...)T format specifier now uses the current time if no
+ argument is supplied.
+
+ee. There is a new variable, BASH_COMPAT, that controls the current shell
+ compatibility level.
+
+ff. The `popd' builtin now treats additional arguments as errors.
+
+gg. The brace expansion code now treats a failed sequence expansion as a
+ simple string and will continue to expand brace terms in the remainder
+ of the word.
+
+hh. Shells started to run process substitutions now run any trap set on EXIT.
+
+ii. The fc builtin now interprets -0 as the current command line.
+
+jj. Completing directory names containing shell variables now adds a trailing
+ slash if the expanded result is a directory.
+
+kk. `cd' has a new `-@' option to browse a file's extended attributes on
+ systems that support O_XATTR.
+
+ll. The test/[/[[ `-v variable' binary operator now understands array
+ references.
+
+2. New Features in Readline
+
+a. Readline is now more responsive to SIGHUP and other fatal signals when
+ reading input from the terminal or performing word completion but no
+ longer attempts to run any not-allowable functions from a signal handler
+ context.
+
+b. There are new bindable commands to search the history for the string of
+ characters between the beginning of the line and the point
+ (history-substring-search-forward, history-substring-search-backward)
+
+c. Readline allows quoted strings as the values of variables when setting
+ them with `set'. As a side effect, trailing spaces and tabs are ignored
+ when setting a string variable's value.
+
+d. The history library creates a backup of the history file when writing it
+ and restores the backup on a write error.
+
+e. New application-settable variable: rl_filename_stat_hook: a function called
+ with a filename before using it in a call to stat(2). Bash uses it to
+ expand shell variables so things like $HOME/Downloads have a slash
+ appended.
+
+f. New bindable function `print-last-kbd-macro', prints the most-recently-
+ defined keyboard macro in a reusable format.
+
+g. New user-settable variable `colored-stats', enables use of colored text
+ to denote file types when displaying possible completions (colored analog
+ of visible-stats).
+
+h. New user-settable variable `keyseq-timout', acts as an inter-character
+ timeout when reading input or incremental search strings.
+
+i. New application-callable function: rl_clear_history. Clears the history list
+ and frees all readline-associated private data.
+
+j. New user-settable variable, show-mode-in-prompt, adds a characters to the
+ beginning of the prompt indicating the current editing mode.
+
+k. New application-settable variable: rl_input_available_hook; function to be
+ called when readline detects there is data available on its input file
+ descriptor.
+
+l. Readline calls an application-set event hook (rl_event_hook) after it gets
+ a signal while reading input (read returns -1/EINTR but readline does not
+ handle the signal immediately) to allow the application to handle or
+ otherwise note it.
+
+m. If the user-settable variable `history-size' is set to a value less than
+ 0, the history list size is unlimited.
+
+n. New application-settable variable: rl_signal_event_hook; function that is
+ called when readline is reading terminal input and read(2) is interrupted
+ by a signal. Currently not called for SIGHUP or SIGTERM.
+
+o. rl_change_environment: new application-settable variable that controls
+ whether or not Readline modifies the environment (currently readline
+ modifies only LINES and COLUMNS).
+
+-------------------------------------------------------------------------------
+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.
projects / platform / upstream / bash.git / blobdiff