1 This is a terse description of the new features added to bash-4.3 since
2 the release of bash-4.2. As always, the manual page (doc/bash.1) is
3 the place to look for complete descriptions.
5 1. New Features in Bash
7 a. The `helptopic' completion action now maps to all the help topics, not just
10 b. The `help' builtin no longer does prefix substring matching, so `help read'
11 does not match `readonly'.
13 c. The shell can be compiled to not display a message about processes that
14 terminate due to SIGTERM.
16 d. Non-interactive shells now react to the setting of checkwinsize and set
17 LINES and COLUMNS after a foreground job exits.
19 e. There is a new shell option, `globasciiranges', which, when set to on,
20 forces globbing range comparisons to use character ordering as if they
21 were run in the C locale.
23 f. There is a new shell option, `direxpand', which makes filename completion
24 expand variables in directory names in the way bash-4.1 did.
26 g. In Posix mode, the `command' builtin does not change whether or not a
27 builtin it shadows is treated as an assignment builtin.
29 h. The `return' and `exit' builtins accept negative exit status arguments.
31 i. The word completion code checks whether or not a filename containing a
32 shell variable expands to a directory name and appends `/' to the word
33 as appropriate. The same code expands shell variables in command names
34 when performing command completion.
36 j. In Posix mode, it is now an error to attempt to define a shell function
37 with the same name as a Posix special builtin.
39 k. When compiled for strict Posix conformance, history expansion is disabled
42 l. The history expansion character (!) does not cause history expansion when
43 followed by the closing quote in a double-quoted string.
45 m. `complete' and its siblings compgen/compopt now takes a new `-o noquote'
46 option to inhibit quoting of the completions.
48 n. Setting HISTSIZE to a value less than zero causes the history list to be
49 unlimited (setting it 0 zero disables the history list).
51 o. Setting HISTFILESIZE to a value less than zero causes the history file size
52 to be unlimited (setting it to 0 causes the history file to be truncated
55 p. The `read' builtin now skips NUL bytes in the input.
57 q. There is a new `bind -X' option to print all key sequences bound to Unix
60 r. When in Posix mode, `read' is interruptible by a trapped signal. After
61 running the trap handler, read returns 128+signal and throws away any
64 s. The command completion code skips whitespace and assignment statements
65 before looking for the command name word to be completed.
67 t. The build process has a new mechanism for constructing separate help files
68 that better reflects the current set of compilation options.
70 u. The -nt and -ot options to test now work with files with nanosecond
73 v. The shell saves the command history in any shell for which history is
74 enabled and HISTFILE is set, not just interactive shells.
76 w. The shell has `nameref' variables and new -n(/+n) options to declare and
77 unset to use them, and a `test -R' option to test for them.
79 x. The shell now allows assigning, referencing, and unsetting elements of
80 indexed arrays using negative subscripts (a[-1]=2, echo ${a[-1]}) which
81 count back from the last element of the array.
83 y. The {x}<word redirection feature now allows words like {array[ind]} and
84 can use variables with special meanings to the shell (e.g., BASH_XTRACEFD).
86 z. There is a new CHILD_MAX special shell variable; its value controls the
87 number of exited child statues the shell remembers.
89 aa. There is a new configuration option (--enable-direxpand-default) that
90 causes the `direxpand' shell option to be enabled by default.
92 bb. Bash does not do anything special to ensure that the file descriptor
93 assigned to X in {x}<foo remains open after the block containing it
96 cc. The `wait' builtin has a new `-n' option to wait for the next child to
99 dd. The `printf' %(...)T format specifier now uses the current time if no
100 argument is supplied.
102 ee. There is a new variable, BASH_COMPAT, that controls the current shell
105 ff. The `popd' builtin now treats additional arguments as errors.
107 gg. The brace expansion code now treats a failed sequence expansion as a
108 simple string and will continue to expand brace terms in the remainder
111 hh. Shells started to run process substitutions now run any trap set on EXIT.
113 2. New Features in Readline
115 a. Readline is now more responsive to SIGHUP and other fatal signals when
116 reading input from the terminal or performing word completion but no
117 longer attempts to run any not-allowable functions from a signal handler
120 b. There are new bindable commands to search the history for the string of
121 characters between the beginning of the line and the point
122 (history-substring-search-forward, history-substring-search-backward)
124 c. Readline allows quoted strings as the values of variables when setting
125 them with `set'. As a side effect, trailing spaces and tabs are ignored
126 when setting a string variable's value.
128 d. The history library creates a backup of the history file when writing it
129 and restores the backup on a write error.
131 e. New application-settable variable: rl_filename_stat_hook: a function called
132 with a filename before using it in a call to stat(2). Bash uses it to
133 expand shell variables so things like $HOME/Downloads have a slash
136 f. New bindable function `print-last-kbd-macro', prints the most-recently-
137 defined keyboard macro in a reusable format.
139 g. New user-settable variable `colored-stats', enables use of colored text
140 to denote file types when displaying possible completions (colored analog
143 h. New user-settable variable `keyseq-timout', acts as an inter-character
144 timeout when reading input or incremental search strings.
146 i. New application-callable function: rl_clear_history. Clears the history list
147 and frees all readline-associated private data.
149 j. New user-settable variable, show-mode-in-prompt, adds a characters to the
150 beginning of the prompt indicating the current editing mode.
152 k. New application-settable variable: rl_input_available_hook; function to be
153 called when readline detects there is data available on its input file
156 l. Readline calls an application-set event hook (rl_event_hook) after it gets
157 a signal while reading input (read returns -1/EINTR but readline does not
158 handle the signal immediately) to allow the application to handle or
161 m. If the user-settable variable `history-size' is set to a value less than
162 0, the history list size is unlimited.
164 n. New application-settable variable: rl_signal_event_hook; function that is
165 called when readline is reading terminal input and read(2) is interrupted
166 by a signal. Currently not called for SIGHUP or SIGTERM.
168 -------------------------------------------------------------------------------
169 This is a terse description of the new features added to bash-4.2 since
170 the release of bash-4.1. As always, the manual page (doc/bash.1) is
171 the place to look for complete descriptions.
173 1. New Features in Bash
175 a. `exec -a foo' now sets $0 to `foo' in an executable shell script without a
178 b. Subshells begun to execute command substitutions or run shell functions or
179 builtins in subshells do not reset trap strings until a new trap is
180 specified. This allows $(trap) to display the caller's traps and the
181 trap strings to persist until a new trap is set.
183 c. `trap -p' will now show signals ignored at shell startup, though their
184 disposition still cannot be modified.
186 d. $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences.
188 e. declare/typeset has a new `-g' option, which creates variables in the
189 global scope even when run in a shell function.
191 f. test/[/[[ have a new -v variable unary operator, which returns success if
192 `variable' has been set.
194 g. Posix parsing changes to allow `! time command' and multiple consecutive
195 instances of `!' (which toggle) and `time' (which have no cumulative
198 h. Posix change to allow `time' as a command by itself to print the elapsed
199 user, system, and real times for the shell and its children.
201 j. $((...)) is always parsed as an arithmetic expansion first, instead of as
202 a potential nested command substitution, as Posix requires.
204 k. A new FUNCNEST variable to allow the user to control the maximum shell
205 function nesting (recursive execution) level.
207 l. The mapfile builtin now supplies a third argument to the callback command:
208 the line about to be assigned to the supplied array index.
210 m. The printf builtin has a new %(fmt)T specifier, which allows time values
211 to use strftime-like formatting.
213 n. There is a new `compat41' shell option.
215 o. The cd builtin has a new Posix-mandated `-e' option.
217 p. Negative subscripts to indexed arrays, previously errors, now are treated
218 as offsets from the maximum assigned index + 1.
220 q. Negative length specifications in the ${var:offset:length} expansion,
221 previously errors, are now treated as offsets from the end of the variable.
223 r. Parsing change to allow `time -p --'.
225 s. Posix-mode parsing change to not recognize `time' as a keyword if the
226 following token begins with a `-'. This means no more Posix-mode
227 `time -p'. Posix interpretation 267.
229 t. There is a new `lastpipe' shell option that runs the last command of a
230 pipeline in the current shell context. The lastpipe option has no
231 effect if job control is enabled.
233 u. History expansion no longer expands the `$!' variable expansion.
235 v. Posix mode shells no longer exit if a variable assignment error occurs
236 with an assignment preceding a command that is not a special builtin.
238 w. Non-interactive mode shells exit if -u is enabled and an attempt is made
239 to use an unset variable with the % or # expansions, the `//', `^', or
240 `,' expansions, or the parameter length expansion.
242 x. Posix-mode shells use the argument passed to `.' as-is if a $PATH search
243 fails, effectively searching the current directory. Posix-2008 change.
245 2. New Features in Readline
247 a. The history library does not try to write the history filename in the
248 current directory if $HOME is unset. This closes a potential security
249 problem if the application does not specify a history filename.
251 b. New bindable variable `completion-display-width' to set the number of
252 columns used when displaying completions.
254 c. New bindable variable `completion-case-map' to cause case-insensitive
255 completion to treat `-' and `_' as identical.
257 d. There are new bindable vi-mode command names to avoid readline's case-
258 insensitive matching not allowing them to be bound separately.
260 e. New bindable variable `menu-complete-display-prefix' causes the menu
261 completion code to display the common prefix of the possible completions
262 before cycling through the list, instead of after.
264 -------------------------------------------------------------------------------
265 This is a terse description of the new features added to bash-4.1 since
266 the release of bash-4.0. As always, the manual page (doc/bash.1) is
267 the place to look for complete descriptions.
269 1. New Features in Bash
271 a. Here-documents within $(...) command substitutions may once more be
272 delimited by the closing right paren, instead of requiring a newline.
274 b. Bash's file status checks (executable, readable, etc.) now take file
275 system ACLs into account on file systems that support them.
277 c. Bash now passes environment variables with names that are not valid
278 shell variable names through into the environment passed to child
281 d. The `execute-unix-command' readline function now attempts to clear and
282 reuse the current line rather than move to a new one after the command
285 e. `printf -v' can now assign values to array indices.
287 f. New `complete -E' and `compopt -E' options that work on the "empty"
288 completion: completion attempted on an empty command line.
290 g. New complete/compgen/compopt -D option to define a `default' completion:
291 a completion to be invoked on command for which no completion has been
292 defined. If this function returns 124, programmable completion is
293 attempted again, allowing a user to dynamically build a set of completions
294 as completion is attempted by having the default completion function
295 install individual completion functions each time it is invoked.
297 h. When displaying associative arrays, subscripts are now quoted.
299 i. Changes to dabbrev-expand to make it more `emacs-like': no space appended
300 after matches, completions are not sorted, and most recent history entries
303 j. The [[ and (( commands are now subject to the setting of `set -e' and the
306 k. The source/. builtin now removes NUL bytes from the file before attempting
309 l. There is a new configuration option (in config-top.h) that forces bash to
310 forward all history entries to syslog.
312 m. A new variable $BASHOPTS to export shell options settable using `shopt' to
315 n. There is a new confgure option that forces the extglob option to be
318 o. New variable $BASH_XTRACEFD; when set to an integer bash will write xtrace
319 output to that file descriptor.
321 p. If the optional left-hand-side of a redirection is of the form {var}, the
322 shell assigns the file descriptor used to $var or uses $var as the file
323 descriptor to move or close, depending on the redirection operator.
325 q. The < and > operators to the [[ conditional command now do string
326 comparison according to the current locale if the compatibility level
329 r. Programmable completion now uses the completion for `b' instead of `a'
330 when completion is attempted on a line like: a $(b c.
332 s. Force extglob on temporarily when parsing the pattern argument to
333 the == and != operators to the [[ command, for compatibility.
335 t. Changed the behavior of interrupting the wait builtin when a SIGCHLD is
336 received and a trap on SIGCHLD is set to be Posix-mode only.
338 u. The read builtin has a new `-N nchars' option, which reads exactly NCHARS
339 characters, ignoring delimiters like newline.
341 v. The mapfile/readarray builtin no longer stores the commands it invokes via
342 callbacks in the history list.
344 w. There is a new `compat40' shopt option.
346 2. New Features in Readline
348 a. New bindable function: menu-complete-backward.
350 b. In the vi insertion keymap, C-n is now bound to menu-complete by default,
351 and C-p to menu-complete-backward.
353 c. When in vi command mode, repeatedly hitting ESC now does nothing, even
354 when ESC introduces a bound key sequence. This is closer to how
355 historical vi behaves.
357 d. New bindable function: skip-csi-sequence. Can be used as a default to
358 consume key sequences generated by keys like Home and End without having
361 e. New application-settable function: rl_filename_rewrite_hook. Can be used
362 to rewite or modify filenames read from the file system before they are
363 compared to the word to be completed.
365 f. New bindable variable: skip-completed-text, active when completing in the
366 middle of a word. If enabled, it means that characters in the completion
367 that match characters in the remainder of the word are "skipped" rather
368 than inserted into the line.
370 g. The pre-readline-6.0 version of menu completion is available as
371 "old-menu-complete" for users who do not like the readline-6.0 version.
373 h. New bindable variable: echo-control-characters. If enabled, and the
374 tty ECHOCTL bit is set, controls the echoing of characters corresponding
375 to keyboard-generated signals.
377 i. New bindable variable: enable-meta-key. Controls whether or not readline
378 sends the smm/rmm sequences if the terminal indicates it has a meta key
379 that enables eight-bit characters.
381 -------------------------------------------------------------------------------
382 This is a terse description of the new features added to bash-4.0 since
383 the release of bash-3.2. As always, the manual page (doc/bash.1) is
384 the place to look for complete descriptions.
386 1. New Features in Bash
388 a. When using substring expansion on the positional parameters, a starting
389 index of 0 now causes $0 to be prefixed to the list.
391 b. The `help' builtin now prints its columns with entries sorted vertically
392 rather than horizontally.
394 c. There is a new variable, $BASHPID, which always returns the process id of
397 d. There is a new `autocd' option that, when enabled, causes bash to attempt
398 to `cd' to a directory name that is supplied as the first word of a
401 e. There is a new `checkjobs' option that causes the shell to check for and
402 report any running or stopped jobs at exit.
404 f. The programmable completion code exports a new COMP_TYPE variable, set to
405 a character describing the type of completion being attempted.
407 g. The programmable completion code exports a new COMP_KEY variable, set to
408 the character that caused the completion to be invoked (e.g., TAB).
410 h. If creation of a child process fails due to insufficient resources, bash
411 will try again several times before reporting failure.
413 i. The programmable completion code now uses the same set of characters as
414 readline when breaking the command line into a list of words.
416 j. The block multiplier for the ulimit -c and -f options is now 512 when in
417 Posix mode, as Posix specifies.
419 k. Changed the behavior of the read builtin to save any partial input received
420 in the specified variable when the read builtin times out. This also
421 results in variables specified as arguments to read to be set to the empty
422 string when there is no input available. When the read builtin times out,
423 it returns an exit status greater than 128.
425 l. The shell now has the notion of a `compatibility level', controlled by
426 new variables settable by `shopt'. Setting this variable currently
427 restores the bash-3.1 behavior when processing quoted strings on the rhs
428 of the `=~' operator to the `[[' command.
430 m. The `ulimit' builtin now has new -b (socket buffer size) and -T (number
433 n. The -p option to `declare' now displays all variable values and attributes
434 (or function values and attributes if used with -f).
436 o. There is a new `compopt' builtin that allows completion functions to modify
437 completion options for existing completions or the completion currently
440 p. The `read' builtin has a new -i option which inserts text into the reply
441 buffer when using readline.
443 q. A new `-E' option to the complete builtin allows control of the default
444 behavior for completion on an empty line.
446 r. There is now limited support for completing command name words containing
449 s. Changed format of internal help documentation for all builtins to roughly
450 follow man page format.
452 t. The `help' builtin now has a new -d option, to display a short description,
453 and a -m option, to print help information in a man page-like format.
455 u. There is a new `mapfile' builtin to populate an array with lines from a
456 given file. The name `readarray' is a synonym.
458 v. If a command is not found, the shell attempts to execute a shell function
459 named `command_not_found_handle', supplying the command words as the
462 w. There is a new shell option: `globstar'. When enabled, the globbing code
463 treats `**' specially -- it matches all directories (and files within
464 them, when appropriate) recursively.
466 x. There is a new shell option: `dirspell'. When enabled, the filename
467 completion code performs spelling correction on directory names during
470 y. The `-t' option to the `read' builtin now supports fractional timeout
473 z. Brace expansion now allows zero-padding of expanded numeric values and
474 will add the proper number of zeroes to make sure all values contain the
475 same number of digits.
477 aa. There is a new bash-specific bindable readline function: `dabbrev-expand'.
478 It uses menu completion on a set of words taken from the history list.
480 bb. The command assigned to a key sequence with `bind -x' now sets two new
481 variables in the environment of the executed command: READLINE_LINE_BUFFER
482 and READLINE_POINT. The command can change the current readline line
483 and cursor position by modifying READLINE_LINE_BUFFER and READLINE_POINT,
486 cc. There is a new &>> redirection operator, which appends the standard output
487 and standard error to the named file.
489 dd. The parser now understands `|&' as a synonym for `2>&1 |', which redirects
490 the standard error for a command through a pipe.
492 ee. The new `;&' case statement action list terminator causes execution to
493 continue with the action associated with the next pattern in the
494 statement rather than terminating the command.
496 ff. The new `;;&' case statement action list terminator causes the shell to
497 test the next set of patterns after completing execution of the current
498 action, rather than terminating the command.
500 gg. The shell understands a new variable: PROMPT_DIRTRIM. When set to an
501 integer value greater than zero, prompt expansion of \w and \W will
502 retain only that number of trailing pathname components and replace
503 the intervening characters with `...'.
505 hh. There are new case-modifying word expansions: uppercase (^[^]) and
506 lowercase (,[,]). They can work on either the first character or
507 array element, or globally. They accept an optional shell pattern
508 that determines which characters to modify. There is an optionally-
509 configured feature to include capitalization operators.
511 ii. The shell provides associative array variables, with the appropriate
512 support to create, delete, assign values to, and expand them.
514 jj. The `declare' builtin now has new -l (convert value to lowercase upon
515 assignment) and -u (convert value to uppercase upon assignment) options.
516 There is an optionally-configurable -c option to capitalize a value at
519 kk. There is a new `coproc' reserved word that specifies a coprocess: an
520 asynchronous command run with two pipes connected to the creating shell.
521 Coprocs can be named. The input and output file descriptors and the
522 PID of the coprocess are available to the calling shell in variables
523 with coproc-specific names.
525 ll. A value of 0 for the -t option to `read' now returns success if there is
526 input available to be read from the specified file descriptor.
528 mm. CDPATH and GLOBIGNORE are ignored when the shell is running in privileged
531 nn. New bindable readline functions shell-forward-word and shell-backward-word,
532 which move forward and backward words delimited by shell metacharacters
533 and honor shell quoting.
535 oo. New bindable readline functions shell-backward-kill-word and shell-kill-word
536 which kill words backward and forward, but use the same word boundaries
537 as shell-forward-word and shell-backward-word.
539 2. New Features in Readline
541 a. A new variable, rl_sort_completion_matches; allows applications to inhibit
542 match list sorting (but beware: some things don't work right if
543 applications do this).
545 b. A new variable, rl_completion_invoking_key; allows applications to discover
546 the key that invoked rl_complete or rl_menu_complete.
548 c. The functions rl_block_sigint and rl_release_sigint are now public and
549 available to calling applications who want to protect critical sections
552 d. The functions rl_save_state and rl_restore_state are now public and
553 available to calling applications; documented rest of readline's state
556 e. A new user-settable variable, `history-size', allows setting the maximum
557 number of entries in the history list.
559 f. There is a new implementation of menu completion, with several improvements
560 over the old; the most notable improvement is a better `completions
563 g. The menu completion code now uses the rl_menu_completion_entry_function
564 variable, allowing applications to provide their own menu completion
567 h. There is support for replacing a prefix of a pathname with a `...' when
568 displaying possible completions. This is controllable by setting the
569 `completion-prefix-display-length' variable. Matches with a common prefix
570 longer than this value have the common prefix replaced with `...'.
572 i. There is a new `revert-all-at-newline' variable. If enabled, readline will
573 undo all outstanding changes to all history lines when `accept-line' is
576 j. If the kernel supports it, readline displays special characters
577 corresponding to a keyboard-generated signal when the signal is received.
579 -------------------------------------------------------------------------------
580 This is a terse description of the new features added to bash-3.2 since
581 the release of bash-3.1. As always, the manual page (doc/bash.1) is
582 the place to look for complete descriptions.
584 1. New Features in Bash
586 a. Changed the parameter pattern replacement functions to not anchor the
587 pattern at the beginning of the string if doing global replacement - that
588 combination doesn't make any sense.
590 b. When running in `word expansion only' mode (--wordexp option), inhibit
591 process substitution.
593 c. Loadable builtins now work on MacOS X 10.[34].
595 d. Shells running in posix mode no longer set $HOME, as POSIX requires.
597 e. The code that checks for binary files being executed as shell scripts now
598 checks only for NUL rather than any non-printing character.
600 f. Quoting the string argument to the [[ command's =~ operator now forces
601 string matching, as with the other pattern-matching operators.
603 2. New Features in Readline
605 a. Calling applications can now set the keyboard timeout to 0, allowing
608 b. The value of SYS_INPUTRC (configurable at compilation time) is now used as
609 the default last-ditch startup file.
611 c. The history file reading functions now allow windows-like \r\n line
614 -------------------------------------------------------------------------------
615 This is a terse description of the new features added to bash-3.1 since
616 the release of bash-3.0. As always, the manual page (doc/bash.1) is
617 the place to look for complete descriptions.
619 1. New Features in Bash
621 a. Bash now understands LC_TIME as a special variable so that time display
622 tracks the current locale.
624 b. BASH_ARGC, BASH_ARGV, BASH_SOURCE, and BASH_LINENO are no longer created
625 as `invisible' variables and may not be unset.
627 c. In POSIX mode, if `xpg_echo' option is enabled, the `echo' builtin doesn't
628 try to interpret any options at all, as POSIX requires.
630 d. The `bg' builtin now accepts multiple arguments, as POSIX seems to specify.
632 e. Fixed vi-mode word completion and glob expansion to perform tilde
635 f. The `**' mathematic exponentiation operator is now right-associative.
637 g. The `ulimit' builtin has new options: -i (max number of pending signals),
638 -q (max size of POSIX message queues), and -x (max number of file locks).
640 h. A bare `%' once again expands to the current job when used as a job
643 i. The `+=' assignment operator (append to the value of a string or array) is
644 now supported for assignment statements and arguments to builtin commands
645 that accept assignment statements.
647 j. BASH_COMMAND now preserves its value when a DEBUG trap is executed.
649 k. The `gnu_errfmt' option is enabled automatically if the shell is running
650 in an emacs terminal window.
652 l. New configuration option: --single-help-strings. Causes long help text
653 to be written as a single string; intended to ease translation.
655 m. The COMP_WORDBREAKS variable now causes the list of word break characters
656 to be emptied when the variable is unset.
658 n. An unquoted expansion of $* when $IFS is empty now causes the positional
659 parameters to be concatenated if the expansion doesn't undergo word
662 o. Bash now inherits $_ from the environment if it appears there at startup.
664 p. New shell option: nocasematch. If non-zero, shell pattern matching ignores
665 case when used by `case' and `[[' commands.
667 q. The `printf' builtin takes a new option: -v var. That causes the output
668 to be placed into var instead of on stdout.
670 r. By default, the shell no longer reports processes dying from SIGPIPE.
672 s. Bash now sets the extern variable `environ' to the export environment it
673 creates, so C library functions that call getenv() (and can't use the
674 shell-provided replacement) get current values of environment variables.
676 t. A new configuration option, `--enable-strict-posix-default', which will
677 build bash to be POSIX conforming by default.
679 u. If compiled for strict POSIX conformance, LINES and COLUMNS may now
680 override the true terminal size.
682 2. New Features in Readline
684 a. The key sequence sent by the keypad `delete' key is now automatically
685 bound to delete-char.
687 b. A negative argument to menu-complete now cycles backward through the
690 c. A new bindable readline variable: bind-tty-special-chars. If non-zero,
691 readline will bind the terminal special characters to their readline
692 equivalents when it's called (on by default).
694 d. New bindable command: vi-rubout. Saves deleted text for possible
695 reinsertion, as with any vi-mode `text modification' command; `X' is bound
696 to this in vi command mode.
698 e. A new external application-controllable variable that allows the LINES
699 and COLUMNS environment variables to set the window size regardless of
700 what the kernel returns: rl_prefer_env_winsize
702 -------------------------------------------------------------------------------
703 This is a terse description of the new features added to bash-3.0 since
704 the release of bash-2.05b. As always, the manual page (doc/bash.1) is
705 the place to look for complete descriptions.
707 1. New Features in Bash
709 a. ANSI string expansion now implements the \x{hexdigits} escape.
711 b. There is a new loadable `strftime' builtin.
713 c. New variable, COMP_WORDBREAKS, which controls the readline completer's
714 idea of word break characters.
716 d. The `type' builtin no longer reports on aliases unless alias expansion
717 will actually be performed.
719 e. HISTCONTROL is now a colon-separated list of values, which permits
720 more extensibility and backwards compatibility.
722 f. HISTCONTROL may now include the `erasedups' option, which causes all lines
723 matching a line being added to be removed from the history list.
725 g. `configure' has a new `--enable-multibyte' argument that permits multibyte
726 character support to be disabled even on systems that support it.
728 h. New variables to support the bash debugger: BASH_ARGC, BASH_ARGV,
729 BASH_SOURCE, BASH_LINENO, BASH_SUBSHELL, BASH_EXECUTION_STRING,
732 i. FUNCNAME has been changed to support the debugger: it's now an array
735 j. for, case, select, arithmetic commands now keep line number information
738 k. There is a new `RETURN' trap executed when a function or sourced script
739 returns (not inherited child processes; inherited by command substitution
740 if function tracing is enabled and the debugger is active).
742 l. New invocation option: --debugger. Enables debugging and turns on new
743 `extdebug' shell option.
745 m. New `functrace' and `errtrace' options to `set -o' cause DEBUG and ERR
746 traps, respectively, to be inherited by shell functions. Equivalent to
747 `set -T' and `set -E' respectively. The `functrace' option also controls
748 whether or not the DEBUG trap is inherited by sourced scripts.
750 n. The DEBUG trap is run before binding the variable and running the action
751 list in a `for' command, binding the selection variable and running the
752 query in a `select' command, and before attempting a match in a `case'
755 o. New `--enable-debugger' option to `configure' to compile in the debugger
758 p. `declare -F' now prints out extra line number and source file information
759 if the `extdebug' option is set.
761 q. If `extdebug' is enabled, a non-zero return value from a DEBUG trap causes
762 the next command to be skipped, and a return value of 2 while in a
763 function or sourced script forces a `return'.
765 r. New `caller' builtin to provide a call stack for the bash debugger.
767 s. The DEBUG trap is run just before the first command in a function body is
768 executed, for the debugger.
770 t. `for', `select', and `case' command heads are printed when `set -x' is
773 u. There is a new {x..y} brace expansion, which is shorthand for {x.x+1,
774 x+2,...,y}. x and y can be integers or single characters; the sequence
775 may ascend or descend; the increment is always 1.
777 v. New ksh93-like ${!array[@]} expansion, expands to all the keys (indices)
780 w. New `force_fignore' shopt option; if enabled, suffixes specified by
781 FIGNORE cause words to be ignored when performing word completion even
782 if they're the only possibilities.
784 x. New `gnu_errfmt' shopt option; if enabled, error messages follow the `gnu
785 style' (filename:lineno:message) format.
787 y. New `-o bashdefault' option to complete and compgen; if set, causes the
788 whole set of bash completions to be performed if the compspec doesn't
791 z. New `-o plusdirs' option to complete and compgen; if set, causes directory
792 name completion to be performed and the results added to the rest of the
793 possible completions.
795 aa. `kill' is available as a builtin even when the shell is built without
798 bb. New HISTTIMEFORMAT variable; value is a format string to pass to
799 strftime(3). If set and not null, the `history' builtin prints out
800 timestamp information according to the specified format when displaying
801 history entries. If set, bash tells the history library to write out
802 timestamp information when the history file is written.
804 cc. The [[ ... ]] command has a new binary `=~' operator that performs
805 extended regular expression (egrep-like) matching.
807 dd. `configure' has a new `--enable-cond-regexp' option (enabled by default)
808 to enable the =~ operator and regexp matching in [[ ... ]].
810 ee. Subexpressions matched by the =~ operator are placed in the new
811 BASH_REMATCH array variable.
813 ff. New `failglob' option that causes an expansion error when pathname
814 expansion fails to produce a match.
816 gg. New `set -o pipefail' option that causes a pipeline to return a failure
817 status if any of the processes in the pipeline fail, not just the last
820 hh. printf builtin understands two new escape sequences: \" and \?.
822 ii. `echo -e' understands two new escape sequences: \" and \?.
824 jj. The GNU `gettext' package and libintl have been integrated; the shell's
825 messages can be translated into different languages.
827 kk. The `\W' prompt expansion now abbreviates $HOME as `~', like `\w'.
829 ll. The error message printed when bash cannot open a shell script supplied
830 as argument 1 now includes the name of the shell, to better identify
831 the error as coming from bash.
833 mm. The parameter pattern removal and substitution expansions are now much
834 faster and more efficient when using multibyte characters.
836 nn. The `jobs', `kill', and `wait' builtins now accept job control notation
837 even if job control is not enabled.
839 oo. The historical behavior of `trap' that allows a missing `action' argument
840 to cause each specified signal's handling to be reset to its default is
841 now only supported when `trap' is given a single non-option argument.
843 2. New Features in Readline
845 a. History expansion has a new `a' modifier equivalent to the `g' modifier
846 for compatibility with the BSD csh.
848 b. History expansion has a new `G' modifier equivalent to the BSD csh `g'
849 modifier, which performs a substitution once per word.
851 c. All non-incremental search operations may now undo the operation of
852 replacing the current line with the history line.
854 d. The text inserted by an `a' command in vi mode can be reinserted with
857 e. New bindable variable, `show-all-if-unmodified'. If set, the readline
858 completer will list possible completions immediately if there is more
859 than one completion and partial completion cannot be performed.
861 f. There is a new application-callable `free_history_entry()' function.
863 g. History list entries now contain timestamp information; the history file
864 functions know how to read and write timestamp information associated
867 h. Four new key binding functions have been added:
869 rl_bind_key_if_unbound()
870 rl_bind_key_if_unbound_in_map()
871 rl_bind_keyseq_if_unbound()
872 rl_bind_keyseq_if_unbound_in_map()
874 i. New application variable, rl_completion_quote_character, set to any
875 quote character readline finds before it calls the application completion
878 j. New application variable, rl_completion_suppress_quote, settable by an
879 application completion function. If set to non-zero, readline does not
880 attempt to append a closing quote to a completed word.
882 k. New application variable, rl_completion_found_quote, set to a non-zero
883 value if readline determines that the word to be completed is quoted.
884 Set before readline calls any application completion function.
886 l. New function hook, rl_completion_word_break_hook, called when readline
887 needs to break a line into words when completion is attempted. Allows
888 the word break characters to vary based on position in the line.
890 m. New bindable command: unix-filename-rubout. Does the same thing as
891 unix-word-rubout, but adds `/' to the set of word delimiters.
893 n. When listing completions, directories have a `/' appended if the
894 `mark-directories' option has been enabled.
896 -------------------------------------------------------------------------------
897 This is a terse description of the new features added to bash-2.05b since
898 the release of bash-2.05a. As always, the manual page (doc/bash.1) is
899 the place to look for complete descriptions.
901 1. New Features in Bash
903 a. If set, TMOUT is the default timeout for the `read' builtin.
905 b. `type' has two new options: `-f' suppresses shell function lookup, and
906 `-P' forces a $PATH search.
908 c. New code to handle multibyte characters.
910 d. `select' was changed to be more ksh-compatible, in that the menu is
911 reprinted each time through the loop only if REPLY is set to NULL.
912 The previous behavior is available as a compile-time option.
914 e. `complete -d' and `complete -o dirnames' now force a slash to be
915 appended to names which are symlinks to directories.
917 f. There is now a bindable edit-and-execute-command readline command,
918 like the vi-mode `v' command, bound to C-xC-e in emacs mode.
920 g. Added support for ksh93-like [:word:] character class in pattern matching.
922 h. The $'...' quoting construct now expands \cX to Control-X.
924 i. A new \D{...} prompt expansion; passes the `...' to strftime and inserts
925 the result into the expanded prompt.
927 j. The shell now performs arithmetic in the largest integer size the
928 machine supports (intmax_t), instead of long.
930 k. If a numeric argument is supplied to one of the bash globbing completion
931 functions, a `*' is appended to the word before expansion is attempted.
933 l. The bash globbing completion functions now allow completions to be listed
934 with double tabs or if `show-all-if-ambiguous' is set.
936 m. New `-o nospace' option for `complete' and `compgen' builtins; suppresses
937 readline's appending a space to the completed word.
939 n. New `here-string' redirection operator: <<< word.
941 o. When displaying variables, function attributes and definitions are shown
942 separately, allowing them to be re-used as input (attempting to re-use
943 the old output would result in syntax errors).
945 p. There is a new configuration option `--enable-mem-scramble', controls
946 bash malloc behavior of writing garbage characters into memory at
947 allocation and free time.
949 q. The `complete' and `compgen' builtins now have a new `-s/-A service'
950 option to complete on names from /etc/services.
952 r. `read' has a new `-u fd' option to read from a specified file descriptor.
954 s. Fix the completion code so that expansion errors in a directory name
955 don't cause a longjmp back to the command loop.
957 t. Fixed word completion inside command substitution to work a little more
960 u. The `printf' %q format specifier now uses $'...' quoting to print the
961 argument if it contains non-printing characters.
963 v. The `declare' and `typeset' builtins have a new `-t' option. When applied
964 to functions, it causes the DEBUG trap to be inherited by the named
965 function. Currently has no effect on variables.
967 w. The DEBUG trap is now run *before* simple commands, ((...)) commands,
968 [[...]] conditional commands, and for ((...)) loops.
970 x. The expansion of $LINENO inside a shell function is only relative to the
971 function start if the shell is interactive -- if the shell is running a
972 script, $LINENO expands to the line number in the script. This is as
975 y. The bash debugger in examples/bashdb has been modified to work with the
976 new DEBUG trap semantics, the command set has been made more gdb-like,
977 and the changes to $LINENO make debugging functions work better. Code
980 z. New [n]<&word- and [n]>&word- redirections from ksh93 -- move fds (dup
983 aa. There is a new `-l' invocation option, equivalent to `--login'.
985 bb. The `hash' builtin has a new `-l' option to list contents in a reusable
986 format, and a `-d' option to remove a name from the hash table.
988 cc. There is now support for placing the long help text into separate files
989 installed into ${datadir}/bash. Not enabled by default; can be turned
990 on with `--enable-separate-helpfiles' option to configure.
992 dd. All builtins that take operands accept a `--' pseudo-option, except
995 ee. The `echo' builtin now accepts \0xxx (zero to three octal digits following
996 the `0') in addition to \xxx (one to three octal digits) for SUSv3/XPG6/
997 POSIX.1-2001 compliance.
1000 2. New Features in Readline
1002 a. Support for key `subsequences': allows, e.g., ESC and ESC-a to both
1003 be bound to readline functions. Now the arrow keys may be used in vi
1006 b. When listing completions, and the number of lines displayed is more than
1007 the screen length, readline uses an internal pager to display the results.
1008 This is controlled by the `page-completions' variable (default on).
1010 c. New code to handle editing and displaying multibyte characters.
1012 d. The behavior introduced in bash-2.05a of deciding whether or not to
1013 append a slash to a completed name that is a symlink to a directory has
1014 been made optional, controlled by the `mark-symlinked-directories'
1015 variable (default is the 2.05a behavior).
1017 e. The `insert-comment' command now acts as a toggle if given a numeric
1018 argument: if the first characters on the line don't specify a
1019 comment, insert one; if they do, delete the comment text
1021 f. New application-settable completion variable:
1022 rl_completion_mark_symlink_dirs, allows an application's completion
1023 function to temporarily override the user's preference for appending
1024 slashes to names which are symlinks to directories.
1026 g. New function available to application completion functions:
1027 rl_completion_mode, to tell how the completion function was invoked
1028 and decide which argument to supply to rl_complete_internal (to list
1031 h. Readline now has an overwrite mode, toggled by the `overwrite-mode'
1032 bindable command, which could be bound to `Insert'.
1034 i. New application-settable completion variable:
1035 rl_completion_suppress_append, inhibits appending of
1036 rl_completion_append_character to completed words.
1038 j. New key bindings when reading an incremental search string: ^W yanks
1039 the currently-matched word out of the current line into the search
1040 string; ^Y yanks the rest of the current line into the search string,
1041 DEL or ^H deletes characters from the search string.
1043 -------------------------------------------------------------------------------
1044 This is a terse description of the new features added to bash-2.05a since
1045 the release of bash-2.05. As always, the manual page (doc/bash.1) is
1046 the place to look for complete descriptions.
1048 1. New Features in Bash
1050 a. Added support for DESTDIR installation root prefix, so you can do a
1051 `make install DESTDIR=bash-root' and do easier binary packaging.
1053 b. Added support for builtin printf "'" flag character as per latest POSIX
1056 c. Support for POSIX.2 printf(1) length specifiers `j', `t', and `z' (from
1059 d. New autoconf macro, RL_LIB_READLINE_VERSION, for use by other applications
1060 (bash doesn't use very much of what it returns).
1062 e. `set [-+]o nolog' is recognized as required by the latest POSIX drafts,
1065 f. New read-only `shopt' option: login_shell. Set to non-zero value if the
1066 shell is a login shell.
1068 g. New `\A' prompt string escape sequence; expands to time in 24 HH:MM format.
1070 h. New `-A group/-g' option to complete and compgen; does group name
1073 i. New `-t' option to `hash' to list hash values for each filename argument.
1075 j. New [-+]O invocation option to set and unset `shopt' options at startup.
1077 k. configure's `--with-installed-readline' option now takes an optional
1078 `=PATH' suffix to set the root of the tree where readline is installed
1081 l. The ksh-like `ERR' trap has been added. The `ERR' trap will be run
1082 whenever the shell would have exited if the -e option were enabled.
1083 It is not inherited by shell functions.
1085 m. `readonly', `export', and `declare' now print variables which have been
1086 given attributes but not set by assigning a value as just a command and
1087 a variable name (like `export foo') when listing, as the latest POSIX
1090 n. `bashbug' now requires that the subject be changed from the default.
1092 o. configure has a new `--enable-largefile' option, like other GNU utilities.
1094 p. `for' loops now allow empty word lists after `in', like the latest POSIX
1097 q. The builtin `ulimit' now takes two new non-numeric arguments: `hard',
1098 meaning the current hard limit, and `soft', meaning the current soft
1099 limit, in addition to `unlimited'
1101 r. `ulimit' now prints the option letter associated with a particular
1102 resource when printing more than one limit.
1104 s. `ulimit' prints `hard' or `soft' when a value is not `unlimited' but is
1105 one of RLIM_SAVED_MAX or RLIM_SAVED_CUR, respectively.
1107 t. The `printf' builtin now handles the %a and %A conversions if they're
1108 implemented by printf(3).
1110 u. The `printf' builtin now handles the %F conversion (just about like %f).
1112 v. The `printf' builtin now handles the %n conversion like printf(3). The
1113 corresponding argument is the name of a shell variable to which the
1116 2. New Features in Readline
1118 a. Added extern declaration for rl_get_termcap to readline.h, making it a
1119 public function (it was always there, just not in readline.h).
1121 b. New #defines in readline.h: RL_READLINE_VERSION, currently 0x0402,
1122 RL_VERSION_MAJOR, currently 4, and RL_VERSION_MINOR, currently 2.
1124 c. New readline variable: rl_readline_version, mirrors RL_READLINE_VERSION.
1126 d. New bindable boolean readline variable: match-hidden-files. Controls
1127 completion of files beginning with a `.' (on Unix). Enabled by default.
1129 e. The history expansion code now allows any character to terminate a
1130 `:first-' modifier, like csh.
1132 f. New bindable variable `history-preserve-point'. If set, the history
1133 code attempts to place the user at the same location on each history
1134 line retrived with previous-history or next-history.
1136 -------------------------------------------------------------------------------
1137 This is a terse description of the new features added to bash-2.05 since
1138 the release of bash-2.04. As always, the manual page (doc/bash.1) is
1139 the place to look for complete descriptions.
1141 1. New Features in Bash
1143 a. Added a new `--init-file' invocation argument as a synonym for `--rcfile',
1144 per the new GNU coding standards.
1146 b. The /dev/tcp and /dev/udp redirections now accept service names as well as
1149 c. `complete' and `compgen' now take a `-o value' option, which controls some
1150 of the aspects of that compspec. Valid values are:
1152 default - perform bash default completion if programmable
1153 completion produces no matches
1154 dirnames - perform directory name completion if programmable
1155 completion produces no matches
1156 filenames - tell readline that the compspec produces filenames,
1157 so it can do things like append slashes to
1158 directory names and suppress trailing spaces
1160 d. A new loadable builtin, realpath, which canonicalizes and expands symlinks
1161 in pathname arguments.
1163 e. When `set' is called without options, it prints function defintions in a
1164 way that allows them to be reused as input. This affects `declare' and
1165 `declare -p' as well. This only happens when the shell is not in POSIX
1166 mode, since POSIX.2 forbids this behavior.
1168 f. Bash-2.05 once again honors the current locale setting when processing
1169 ranges within pattern matching bracket expressions (e.g., [A-Z]).
1171 2. New Features in Readline
1173 a. The blink timeout for paren matching is now settable by applications,
1174 via the rl_set_paren_blink_timeout() function.
1176 b. _rl_executing_macro has been renamed to rl_executing_macro, which means
1177 it's now part of the public interface.
1179 c. Readline has a new variable, rl_readline_state, which is a bitmap that
1180 encapsulates the current state of the library; intended for use by
1181 callbacks and hook functions.
1183 d. New application-callable function rl_set_prompt(const char *prompt):
1184 expands its prompt string argument and sets rl_prompt to the result.
1186 e. New application-callable function rl_set_screen_size(int rows, int cols):
1187 public method for applications to set readline's idea of the screen
1190 f. New function, rl_get_screen_size (int *rows, int *columns), returns
1191 readline's idea of the screen dimensions.
1193 g. The timeout in rl_gather_tyi (readline keyboard input polling function)
1194 is now settable via a function (rl_set_keyboard_input_timeout()).
1196 h. Renamed the max_input_history variable to history_max_entries; the old
1197 variable is maintained for backwards compatibility.
1199 i. The list of characters that separate words for the history tokenizer is
1200 now settable with a variable: history_word_delimiters. The default
1203 -------------------------------------------------------------------------------
1204 This is a terse description of the new features added to bash-2.04 since
1205 the release of bash-2.03. As always, the manual page (doc/bash.1) is
1206 the place to look for complete descriptions.
1208 1. New Features in Bash
1210 a. The history builtin has a `-d offset' option to delete the history entry
1211 at position `offset'.
1213 b. The prompt expansion code has two new escape sequences: \j, the number of
1214 active jobs; and \l, the basename of the shell's tty device name.
1216 c. The `bind' builtin has a new `-x' option to bind key sequences to shell
1219 d. There is a new shell option, no_empty_command_completion, which, when
1220 enabled, disables command completion when TAB is typed on an empty line.
1222 e. The `help' builtin has a `-s' option to just print a builtin's usage
1225 f. There are several new arithmetic operators: id++, id-- (variable
1226 post-increment/decrement), ++id, --id (variable pre-increment/decrement),
1227 expr1 , expr2 (comma operator).
1229 g. There is a new ksh-93 style arithmetic for command:
1230 for ((expr1 ; expr2; expr3 )); do list; done
1232 h. The `read' builtin has a number of new options:
1233 -t timeout only wait timeout seconds for input
1234 -n nchars only read nchars from input instead of a full line
1235 -d delim read until delim rather than newline
1236 -s don't echo input chars as they are read
1238 i. The redirection code now handles several filenames specially:
1239 /dev/fd/N, /dev/stdin, /dev/stdout, and /dev/stderr, whether or
1240 not they are present in the file system.
1242 j. The redirection code now recognizes pathnames of the form
1243 /dev/tcp/host/port and /dev/udp/host/port, and tries to open a socket
1244 of the appropriate type to the specified port on the specified host.
1246 k. The ksh-93 ${!prefix*} expansion, which expands to the names of all
1247 shell variables with prefix PREFIX, has been implemented.
1249 l. There is a new dynamic variable, FUNCNAME, which expands to the name of
1250 a currently-executing function. Assignments to FUNCNAME have no effect.
1252 m. The GROUPS variable is no longer readonly; assignments to it are silently
1253 discarded. This means it can be unset.
1255 n. A new programmable completion facility, with two new builtin commands:
1256 complete and compgen.
1258 o. configure has a new option, `--enable-progcomp', to compile in the
1259 programmable completion features (enabled by default).
1261 p. `shopt' has a new option, `progcomp', to enable and disable programmable
1262 completion at runtime.
1264 q. Unsetting HOSTFILE now clears the list of hostnames used for completion.
1266 r. configure has a new option, `--enable-bash-malloc', replacing the old
1267 `--with-gnu-malloc' (which is still present for backwards compatibility).
1269 s. There is a new manual page describing rbash, the restricted shell.
1271 t. `bashbug' has new `--help' and `--version' options.
1273 u. `shopt' has a new `xpg_echo' option, which controls the behavior of
1274 `echo' with respect to backslash-escaped characters at runtime.
1276 v. If NON_INTERACTIVE_LOGIN_SHELLS is defined, all login shells read the
1277 startup files, even if they are not interactive.
1279 w. The LC_NUMERIC variable is now treated specially, and used to set the
1280 LC_NUMERIC locale category for number formatting, e.g., when `printf'
1281 displays floating-point numbers.
1283 2. New features in Readline
1285 a. Parentheses matching is now always compiled into readline, and enabled
1286 or disabled when the value of the `blink-matching-paren' variable is
1289 b. MS-DOS systems now use ~/_inputrc as the last-ditch inputrc filename.
1291 c. MS-DOS systems now use ~/_history as the default history file.
1293 d. history-search-{forward,backward} now leave the point at the end of the
1294 line when the string to search for is empty, like
1295 {reverse,forward}-search-history.
1297 e. history-search-{forward,backward} now leave the last history line found
1298 in the readline buffer if the second or subsequent search fails.
1300 f. New function for use by applications: rl_on_new_line_with_prompt, used
1301 when an application displays the prompt itself before calling readline().
1303 g. New variable for use by applications: rl_already_prompted. An application
1304 that displays the prompt itself before calling readline() must set this to
1307 h. A new variable, rl_gnu_readline_p, always 1. The intent is that an
1308 application can verify whether or not it is linked with the `real'
1309 readline library or some substitute.
1311 -------------------------------------------------------------------------------
1312 This is a terse description of the new features added to bash-2.03 since
1313 the release of bash-2.02. As always, the manual page (doc/bash.1) is
1314 the place to look for complete descriptions.
1316 1. New Features in Bash
1318 a. New `shopt' option, `restricted_shell', indicating whether or not the
1319 shell was started in restricted mode, for use in startup files.
1321 b. Filename generation is now performed on the words between ( and ) in
1322 array assignments (which it probably should have done all along).
1324 c. OLDPWD is now auto-exported, as POSIX.2 seems to require.
1326 d. ENV and BASH_ENV are read-only variables in a restricted shell.
1328 e. A change was made to the startup file code so that any shell begun with
1329 the `--login' option, even non-interactive shells, will source the login
1330 shell startup files.
1332 2. New Features in Readline
1334 a. Many changes to the signal handling:
1335 o Readline now catches SIGQUIT and cleans up the tty before returning;
1336 o A new variable, rl_catch_signals, is available to application writers
1337 to indicate to readline whether or not it should install its own
1338 signal handlers for SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP,
1339 SIGTTIN, and SIGTTOU;
1340 o A new variable, rl_catch_sigwinch, is available to application
1341 writers to indicate to readline whether or not it should install its
1342 own signal handler for SIGWINCH, which will chain to the calling
1343 applications's SIGWINCH handler, if one is installed;
1344 o There is a new function, rl_free_line_state, for application signal
1345 handlers to call to free up the state associated with the current
1346 line after receiving a signal;
1347 o There is a new function, rl_cleanup_after_signal, to clean up the
1348 display and terminal state after receiving a signal;
1349 o There is a new function, rl_reset_after_signal, to reinitialize the
1350 terminal and display state after an application signal handler
1351 returns and readline continues
1353 b. There is a new function, rl_resize_terminal, to reset readline's idea of
1354 the screen size after a SIGWINCH.
1356 c. New public functions: rl_save_prompt and rl_restore_prompt. These were
1357 previously private functions with a `_' prefix.
1359 d. New function hook: rl_pre_input_hook, called just before readline starts
1360 reading input, after initialization.
1362 e. New function hook: rl_display_matches_hook, called when readline would
1363 display the list of completion matches. The new function
1364 rl_display_match_list is what readline uses internally, and is available
1365 for use by application functions called via this hook.
1367 f. New bindable function, delete-char-or-list, like tcsh.
1369 g. A new variable, rl_erase_empty_line, which, if set by an application using
1370 readline, will cause readline to erase, prompt and all, lines on which the
1371 only thing typed was a newline.
1373 h. New bindable variable: `isearch-terminators'.
1375 i. New bindable function: `forward-backward-delete-char' (unbound by default).
1377 -------------------------------------------------------------------------------
1378 This is a terse description of the new features added to bash-2.02 since
1379 the release of bash-2.01.1. As always, the manual page (doc/bash.1) is
1380 the place to look for complete descriptions.
1382 1. New Features in Bash
1384 a. A new version of malloc, based on the older GNU malloc, that has many
1385 changes, is more page-based, is more conservative with memory usage,
1386 and does not `orphan' large blocks when they are freed.
1388 b. A new version of gmalloc, based on the old GLIBC malloc, with many
1389 changes and range checking included by default.
1391 c. A new implementation of fnmatch(3) that includes full POSIX.2 Basic
1392 Regular Expression matching, including character classes, collating
1393 symbols, equivalence classes, and support for case-insensitive pattern
1396 d. ksh-88 egrep-style extended pattern matching ([@+*?!](patlist)) has been
1397 implemented, controlled by a new `shopt' option, `extglob'.
1399 e. There is a new ksh-like `[[' compound command, which implements
1400 extended `test' functionality.
1402 f. There is a new `printf' builtin, implemented according to the POSIX.2
1405 g. There is a new feature for command substitution: $(< filename) now expands
1406 to the contents of `filename', with any trailing newlines removed
1407 (equivalent to $(cat filename)).
1409 h. There are new tilde prefixes which expand to directories from the
1412 i. There is a new `**' arithmetic operator to do exponentiation.
1414 j. There are new configuration options to control how bash is linked:
1415 `--enable-profiling', to allow bash to be profiled with gprof, and
1416 `--enable-static-link', to allow bash to be linked statically.
1418 k. There is a new configuration option, `--enable-cond-command', which
1419 controls whether or not the `[[' command is included. It is on by
1422 l. There is a new configuration option, `--enable-extended-glob', which
1423 controls whether or not the ksh extended globbing feature is included.
1424 It is enabled by default.
1426 m. There is a new configuration #define in config.h.top that, when enabled,
1427 will cause all login shells to source /etc/profile and one of the user-
1428 specific login shell startup files, whether or not the shell is
1431 n. There is a new invocation option, `--dump-po-strings', to dump
1432 a shell script's translatable strings ($"...") in GNU `po' format.
1434 o. There is a new `shopt' option, `nocaseglob', to enable case-insensitive
1435 pattern matching when globbing filenames and using the `case' construct.
1437 p. There is a new `shopt' option, `huponexit', which, when enabled, causes
1438 the shell to send SIGHUP to all jobs when an interactive login shell
1441 q. `bind' has a new `-u' option, which takes a readline function name as an
1442 argument and unbinds all key sequences bound to that function in a
1445 r. `disown' now has `-a' and `-r' options, to limit operation to all jobs
1446 and running jobs, respectively.
1448 s. The `shopt' `-p' option now causes output to be displayed in a reusable
1451 t. `test' has a new `-N' option, which returns true if the filename argument
1452 has been modified since it was last accessed.
1454 u. `umask' now has a `-p' option to print output in a reusable format.
1456 v. A new escape sequence, `\xNNN', has been added to the `echo -e' and $'...'
1457 translation code. It expands to the character whose ascii code is NNN
1460 w. The prompt string expansion code has a new `\r' escape sequence.
1462 x. The shell may now be cross-compiled for the CYGWIN32 environment on
1465 2. New Features in Readline
1467 a. There is now an option for `iterative' yank-last-arg handline, so a user
1468 can keep entering `M-.', yanking the last argument of successive history
1471 b. New variable, `print-completions-horizontally', which causes completion
1472 matches to be displayed across the screen (like `ls -x') rather than up
1473 and down the screen (like `ls').
1475 c. New variable, `completion-ignore-case', which causes filename completion
1476 and matching to be performed case-insensitively.
1478 d. There is a new bindable command, `magic-space', which causes history
1479 expansion to be performed on the current readline buffer and a space to
1480 be inserted into the result.
1482 e. There is a new bindable command, `menu-complete', which enables tcsh-like
1483 menu completion (successive executions of menu-complete insert a single
1484 completion match, cycling through the list of possible completions).
1486 f. There is a new bindable command, `paste-from-clipboard', for use on Win32
1487 systems, to insert the text from the Win32 clipboard into the editing
1490 g. The key sequence translation code now understands printf-style backslash
1491 escape sequences, including \NNN octal escapes. These escape sequences
1492 may be used in key sequence definitions or macro values.
1494 h. An `$include' inputrc file parser directive has been added.
1496 -------------------------------------------------------------------------------
1497 This is a terse description of the new features added to bash-2.01 since
1498 the release of bash-2.0. As always, the manual page (doc/bash.1) is the
1499 place to look for complete descriptions.
1501 1. New Features in Bash
1503 a. There is a new builtin array variable: GROUPS, the set of groups to which
1504 the user belongs. This is used by the test suite.
1506 2. New Features in Readline
1508 a. If a key sequence bound to `universal-argument' is read while reading a
1509 numeric argument started with `universal-argument', it terminates the
1510 argument but is otherwise ignored. This provides a way to insert multiple
1511 instances of a digit string, and is how GNU emacs does it.
1513 -------------------------------------------------------------------------------
1514 This is a terse description of the new features added to bash-2.0 since
1515 the release of bash-1.14.7. As always, the manual page (doc/bash.1) is
1516 the place to look for complete descriptions.
1518 1. New Features in Bash
1520 a. There is a new invocation option, -D, that dumps translatable strings
1523 b. The `long' invocation options must now be prefixed with `--'.
1525 c. New long invocation options: --dump-strings, --help, --verbose
1527 d. The `nolineediting' invocation option was renamed to `noediting'.
1529 e. The `nobraceexpansion' and `quiet' long invocation options were removed.
1531 f. The `--help' and `--version' long options now work as the GNU coding
1534 g. If invoked as `sh', bash now enters posix mode after reading the
1535 startup files, and reads and executes commands from the file named
1536 by $ENV if interactive (as POSIX.2 specifies). A login shell invoked
1537 as `sh' reads $ENV after /etc/profile and ~/.profile.
1539 h. There is a new reserved word, `time', for timing pipelines, builtin
1540 commands, and shell functions. It uses the value of the TIMEFORMAT
1541 variable as a format string describing how to print the timing
1544 i. The $'...' quoting syntax expands ANSI-C escapes in ... and leaves the
1545 result single-quoted.
1547 j. The $"..." quoting syntax performs locale-specific translation of ...
1548 and leaves the result double-quoted.
1550 k. LINENO now works correctly in functions.
1552 l. New variables: DIRSTACK, PIPESTATUS, BASH_VERSINFO, HOSTNAME, SHELLOPTS,
1553 MACHTYPE. The first three are array variables.
1555 m. The BASH_VERSION and BASH_VERSINFO variables now include the shell's
1556 `release status' (alpha[N], beta[N], release).
1558 n. Some variables have been removed: MAIL_WARNING, notify, history_control,
1559 command_oriented_history, glob_dot_filenames, allow_null_glob_expansion,
1560 nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and
1561 cdable_vars. Most of them are now implemented with the new `shopt'
1562 builtin; others were already implemented by `set'.
1564 o. Bash now uses some new variables: LC_ALL, LC_MESSAGES, LC_CTYPE,
1565 LC_COLLATE, LANG, GLOBIGNORE, HISTIGNORE.
1567 p. The shell now supports integer-indexed arrays of unlimited length,
1568 with a new compound assignment syntax and changes to the appropriate
1569 builtin commands (declare/typeset, read, readonly, etc.). The array
1570 index may be an arithmetic expression.
1572 q. ${!var}: indirect variable expansion, equivalent to eval \${$var}.
1574 r. ${paramter:offset[:length]}: variable substring extraction.
1576 s. ${parameter/pattern[/[/]string]}: variable pattern substitution.
1578 t. The $[...] arithmetic expansion syntax is no longer supported, in
1581 u. Aliases can now be expanded in shell scripts with a shell option
1582 (shopt expand_aliases).
1584 v. History and history expansion can now be used in scripts with
1585 set -o history and set -H.
1587 w. All builtins now return an exit status of 2 for incorrect usage.
1589 x. Interactive shells resend SIGHUP to all running or stopped children
1590 if (and only if) they exit due to a SIGHUP.
1592 y. New prompting expansions: \a, \e, \H, \T, \@, \v, \V.
1594 z. Variable expansion in prompt strings is now controllable via a shell
1595 option (shopt promptvars).
1597 aa. Bash now defaults to using command-oriented history.
1599 bb. The history file ($HISTFILE) is now truncated to $HISTFILESIZE after
1602 cc. The POSIX.2 conditional arithmetic evaluation syntax (expr ? expr : expr)
1603 has been implemented.
1605 dd. Each builtin now accepts `--' to signify the end of the options, except
1606 as documented (echo, etc.).
1608 ee. All builtins use -p to display values in a re-readable format where
1609 appropriate, except as documented (echo, type, etc.).
1611 ff. The `alias' builtin has a new -p option.
1613 gg. Changes to the `bind' builtin:
1614 o has new options: -psPSVr.
1615 o the `-d' option was renamed to `-p'
1616 o the `-v' option now dumps variables; the old `-v' is now `-P'
1618 hh. The `bye' synonym for `exit' was removed.
1620 ii. The -L and -P options to `cd' and `pwd' have been documented.
1622 jj. The `cd' builtin now does spelling correction on the directory name
1623 by default. This is settable with a shell option (shopt cdspell).
1625 kk. The `declare' builtin has new options: -a, -F, -p.
1627 ll. The `dirs' builtin has new options: -c, -p, -v.
1629 mm. The new `disown' builtin removes jobs from the shell's jobs table
1630 or inhibits the resending of SIGHUP when the shell receives a
1633 nn. The `echo' builtin has a new escape character: \e.
1635 oo. The `enable' builtin can now load new builtins dynamically from shared
1636 objects on systems with the dlopen/dlsym interface. There are a number
1637 of examples in the examples/loadables directory. There are also
1638 new options: -d, -f, -s, -p.
1640 pp. The `-all' option to `enable' was removed in favor of `-a'.
1642 qq. The `exec' builtin has new options: -l, -c, -a.
1644 rr. The `hash' builtin has a new option: -p.
1646 ss. The `history' builtin has new options: -c, -p, -s.
1648 tt. The `jobs' builtin has new options: -r, -s.
1650 uu. The `kill' builtin has new options: -n signum, -l signame.
1652 vv. The `pushd' and `popd' builtins have a new option: -n.
1654 ww. The `read' builtin has new options: -p prompt, -e, -a.
1656 xx. The `readonly' builtin has a new -a option, and the -n option was removed.
1658 yy. Changes to the `set' builtin:
1659 o new options: -B, -o keyword, -o onecmd, -o history
1660 o options removed: -l, -d, -o nohash
1661 o options changed: +o, -h, -o hashall
1662 o now displays variables in a format that can be re-read as input
1664 zz. The new `shopt' builtin controls shell optional behavior previously
1665 done by setting and unsetting certain shell variables.
1667 aaa. The `test' builtin has new operators: -o option, s1 == s2, s1 < s2,
1668 and s1 > s2, where s1 and s2 are strings.
1670 bbb. There is a new trap, DEBUG, executed after every simple command.
1672 ccc. The `trap' builtin has a new -p option.
1674 ddd. The `ulimit' builtin has a new -l option on 4.4BSD-based systems.
1676 eee. The PS1, PS2, PATH, and IFS variables may now be unset.
1678 fff. The restricted shell mode has been expanded and is now documented.
1680 ggg. Security improvements:
1681 o functions are not imported from the environment if running setuid
1683 o no startup files are sourced if running setuid or with -p
1685 hhh. The documentation has been overhauled: the texinfo manual was
1686 expanded, and HTML versions of the man page and texinfo manual
1689 iii. Changes to Posix mode:
1690 o Command lookup now finds special builtins before shell functions.
1691 o Failure of a special builtin causes a non-interactive shell to
1692 exit. Failures are defined in the POSIX.2 specification.
1693 o If the `cd' builtin finds a directory to change to using $CDPATH,
1694 the value assigned to PWD when `cd' completes does not contain
1696 o A non-interactive shell exits if a variable assignment error
1697 occurs when no command name follows the assignment statements.
1698 o A non-interactive shell exits if the interation variable in a
1699 `for' statement or the selection variable in a `select' statement
1700 is read-only or another variable assignment error occurs.
1701 o The `<>' redirection operator now opens a file for both stdin and
1702 stdout by default, not just when in posix mode.
1703 o Assignment statements preceding special builtins now persist in
1704 the shell's environment when the builtin completes.
1706 Posix mode is now completely POSIX.2-compliant (modulo bugs). When
1707 invoked as sh, bash should be completely POSIX.2-compliant.
1709 jjj. The default value of PS1 is now "\s-\v\$ ".
1711 kkk. The ksh-like ((...)) arithmetic command syntax has been implemented.
1712 This is exactly equivalent to `let "..."'.
1714 lll. Integer constants have been extended to base 64.
1716 mmm. The `ulimit' builtin now sets both hard and soft limits and reports the
1717 soft limit by default.
1719 2. New Features in Readline
1721 a. New variables: enable-keypad, input-meta (new name for meta-flag),
1722 mark-directories, visible-stats (now documented), disable-completion,
1725 b. New bindable commands: kill-region, copy-region-as-kill,
1726 copy-backward-word, copy-forward-word, set-mark, exchange-point-and-mark,
1727 character-search, character-search-backward, insert-comment,
1728 glob-expand-word, glob-list-expansions, dump-variables, dump-macros.
1730 c. New emacs keybindings: delete-horizontal-space (M-\),
1731 insert-completions (M-*), possible-completions (M-=).
1733 d. The history-search-backward and history-search-forward commands were
1734 modified to be the same as previous-line and next-line if point is at
1735 the start of the line.
1737 e. More file types are available for the visible-stats mode.
1739 3. Changes of interest in the Bash implementation
1741 a. There is a new autoconf-based configuration mechanism.
1743 b. More things have been moved from Posix mode to standard shell behavior.
1745 c. The trace output (set -x) now inserts quotes where necessary so it can
1748 d. There is a compile-time option for a system-wide interactive shell
1749 startup file (disabled by default).
1751 e. The YACC grammar is smaller and tighter, and all 66 shift-reduce
1752 conflicts are gone. Several parsing bugs have been fixed.
1754 f. Builtin option parsing has been regularized (using internal_getopt()),
1755 with the exception of `echo', `type', and `set'.
1757 g. Builtins now return standard usage messages constructed from the
1758 `short doc' used by the help builtin.
1760 h. Completion now quotes using backslashes by default, but honors
1761 user-supplied quotes.
1763 i. The GNU libc malloc is available as a configure-time option.
1765 j. There are more internationalization features; bash uses gettext if
1766 it is available. The $"..." translation syntax uses the current
1769 k. There is better reporting of job termination when the shell is not
1772 l. The shell is somewhat more efficient: it uses a little less memory and
1773 makes fewer system calls.
1775 4. Changes of interest in the Readline implementation
1777 a. There is now support for readline `callback' functions.
1779 b. There is now support for user-supplied input, redisplay, and terminal
1780 preparation functions.
1782 c. Most of the shell-specific code in readline has been generalized or
1785 d. Most of the annoying redisplay bugs have been fixed, notably the problems
1786 with incremental search and excessive redrawing when special characters
1787 appear in the prompt string.
1789 e. There are new library functions and variables available to application
1790 writers, most having to do with completion and quoting.
1792 f. The NEWLINE character (^J) is now treated as a search terminator by the
1793 incremental search functions.
1794 -------------------------------------------------------------------------------
1796 Copying and distribution of this file, with or without modification,
1797 are permitted in any medium without royalty provided the copyright
1798 notice and this notice are preserved. This file is offered as-is,
1799 without any warranty.