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[1166]1This is a terse description of the new features added to bash-5.1 since
2the release of bash-5.0. As always, the manual page (doc/bash.1) is
3the place to look for complete descriptions.
4
51. New Features in Bash
6
7a. `bind -x' now supports different bindings for different editing modes and
8 keymaps.
9
10b. Bash attempts to optimize the number of times it forks when executing
11 commands in subshells and from `bash -c'.
12
13c. Here documents and here strings now use pipes for the expanded document if
14 it's smaller than the pipe buffer size, reverting to temporary files if it's
15 larger.
16
17d. There are new loadable builtins: mktemp, accept, mkfifo, csv, cut/lcut
18
19e. In posix mode, `trap -p' now displays signals whose disposition is SIG_DFL
20 and those that were SIG_IGN when the shell starts.
21
22f. The shell now expands the history number (e.g., in PS1) even if it is not
23 currently saving commands to the history list.
24
25g. `read -e' may now be used with arbitrary file descriptors (`read -u N').
26
27h. The `select' builtin now runs traps if its internal call to the read builtin
28 is interrupted by a signal.
29
30i. SRANDOM: a new variable that expands to a 32-bit random number that is not
31 produced by an LCRNG, and uses getrandom/getentropy, falling back to
32 /dev/urandom or arc4random if available. There is a fallback generator if
33 none of these are available.
34
35j. shell-transpose-words: a new bindable readline command that uses the same
36 definition of word as shell-forward-word, etc.
37
38k. The shell now adds default bindings for shell-forward-word,
39 shell-backward-word, shell-transpose-words, and shell-kill-word.
40
41l. Bash now allows ARGV0 appearing in the initial shell environment to set $0.
42
43m. If `unset' is executed without option arguments, bash tries to unset a shell
44 function if a name argument cannot be a shell variable name because it's not
45 an identifier.
46
47n. The `test -N' operator uses nanosecond timestamp granularity if it's
48 available.
49
50o. Bash posix mode now treats assignment statements preceding shell function
51 definitions the same as in its default mode, since POSIX has changed and
52 no longer requires those assignments to persist after the function returns
53 (POSIX interp 654).
54
55p. BASH_REMATCH is no longer readonly.
56
57q. wait: has a new -p VARNAME option, which stores the PID returned by `wait -n'
58 or `wait' without arguments.
59
60r. Sorting the results of pathname expansion now uses byte-by-byte comparisons
61 if two strings collate equally to impose a total order; the result of a
62 POSIX interpretation.
63
64s. Bash now allows SIGINT trap handlers to execute recursively.
65
66t. Bash now saves and restores state around setting and unsetting posix mode,
67 instead of having unsetting posix mode set a known state.
68
69u. Process substitution is now available in posix mode.
70
71v. READLINE_MARK: a new variable available while executing commands bound with
72 `bind -x', contains the value of the mark.
73
74w. Bash removes SIGCHLD from the set of blocked signals if it's blocked at shell
75 startup.
76
77x. `test -v N' can now test whether or not positional parameter N is set.
78
79y. `local' now honors the `-p' option to display all local variables at the
80 current context.
81
82z. The `@a' variable transformation now prints attributes for unset array
83 variables.
84
85aa. The `@A' variable transformation now prints a declare command that sets a
86 variable's attributes if the variable has attributes but is unset.
87
88bb. `declare' and `local' now have a -I option that inherits attributes and
89 value from a variable with the same name at a previous scope.
90
91cc. When run from a -c command, `jobs' now reports the status of completed jobs.
92
93dd. New `U', `u', and `L' parameter transformations to convert to uppercase,
94 convert first character to uppercase, and convert to lowercase,
95 respectively.
96
97ee. PROMPT_COMMAND: can now be an array variable, each element of which can
98 contain a command to be executed like a string PROMPT_COMMAND variable.
99
100ff. `ulimit' has a -R option to report and set the RLIMIT_RTTIME resource.
101
102gg. Associative arrays may be assigned using a list of key-value pairs within
103 a compound assignment. Compound assignments where the words are not of
104 the form [key]=value are assumed to be key-value assignments. A missing or
105 empty key is an error; a missing value is treated as NULL. Assignments may
106 not mix the two forms.
107
108hh. New `K' parameter transformation to display associative arrays as key-
109 value pairs.
110
111ii. Writing history to syslog now handles messages longer than the syslog max
112 length by writing multiple messages with a sequence number.
113
114jj. SECONDS and RANDOM may now be assigned using arithmetic expressions, since
115 they are nominally integer variables. LINENO is not an integer variable.
116
117kk. Bash temporarily suppresses the verbose option when running the DEBUG trap
118 while running a command from the `fc' builtin.
119
120ll. `wait -n' now accepts a list of job specifications as arguments and will
121 wait for the first one in the list to change state.
122
123mm. The associative array implementation can now dynamically increase the
124 size of the hash table based on insertion patterns.
125
126nn. HISTFILE is now readonly in a restricted shell.
127
128oo. The bash malloc now returns memory that is 16-byte aligned on 64-bit
129 systems.
130
131pp. If the hash builtin is listing hashed filenames portably, don't print
132 anything if the table is empty.
133
134qq. GLOBIGNORE now ignores `.' and `..' as a terminal pathname component.
135
136rr. Bash attempts to optimize away forks in the last command in a function body
137 under appropriate circumstances.
138
139ss. The globbing code now uses fnmatch(3) to check collation elements (if
140 available) even in cases without multibyte characters.
141
142tt. The `fg' and `bg' builtins now return an error in a command substitution
143 when asked to restart a job inherited from the parent shell.
144
145uu. The shell now attempts to unlink all FIFOs on exit, whether a consuming
146 process has finished with them or not.
147
148vv. There is a new contributed loadable builtin: asort.
149
1502. New Features in Readline
151
152a. If a second consecutive completion attempt produces matches where the first
153 did not, treat it as a new completion attempt and insert a match as
154 appropriate.
155
156b. Bracketed paste mode works in more places: incremental search strings, vi
157 overstrike mode, character search, and reading numeric arguments.
158
159c. Readline automatically switches to horizontal scrolling if the terminal has
160 only one line.
161
162d. Unbinding all key sequences bound to a particular readline function now
163 descends into keymaps for multi-key sequences.
164
165e. rl-clear-display: new bindable command that clears the screen and, if
166 possible, the scrollback buffer (bound to emacs mode M-C-l by default).
167
168f. New active mark and face feature: when enabled, it will highlight the text
169 inserted by a bracketed paste (the `active region') and the text found by
170 incremental and non-incremental history searches. This is tied to bracketed
171 paste and can be disabled by turning off bracketed paste.
172
173g. Readline sets the mark in several additional commands.
174
175h. Bracketed paste mode is enabled by default.
176
177i. Readline tries to take advantage of the more regular structure of UTF-8
178 characters to identify the beginning and end of characters when moving
179 through the line buffer.
180
181j. The bindable operate-and-get-next command (and its default bindings) are
182 now part of readline instead of a bash-specific addition.
183
184k. The signal cleanup code now blocks SIGINT while processing after a SIGINT.
185
186-------------------------------------------------------------------------------
187This is a terse description of the new features added to bash-5.0 since
188the release of bash-4.4. As always, the manual page (doc/bash.1) is
189the place to look for complete descriptions.
190
1911. New Features in Bash
192
193a. The `wait' builtin can now wait for the last process substitution created.
194
195b. There is an EPOCHSECONDS variable, which expands to the time in seconds
196 since the Unix epoch.
197
198c. There is an EPOCHREALTIME variable, which expands to the time in seconds
199 since the Unix epoch with microsecond granularity.
200
201d. New loadable builtins: rm, stat, fdflags.
202
203e. BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment.
204
205f. When supplied a numeric argument, the shell-expand-line bindable readline
206 command does not perform quote removal and suppresses command and process
207 substitution.
208
209g. `history -d' understands negative arguments: negative arguments offset from
210 the end of the history list.
211
212h. The `name' argument to the `coproc' reserved word now undergoes word
213 expansion, so unique coprocs can be created in loops.
214
215i. A nameref name resolution loop in a function now resolves to a variable by
216 that name in the global scope.
217
218j. The `wait' builtin now has a `-f' option, which signifies to wait until the
219 specified job or process terminates, instead of waiting until it changes
220 state.
221
222k. There is a define in config-top.h that allows the shell to use a static
223 value for $PATH, overriding whatever is in the environment at startup, for
224 use by the restricted shell.
225
226l. Process substitution does not inherit the `v' option, like command
227 substitution.
228
229m. If a non-interactive shell with job control enabled detects that a foreground
230 job died due to SIGINT, it acts as if it received the SIGINT.
231
232n. The SIGCHLD trap is run once for each exiting child process even if job
233 control is not enabled when the shell is in Posix mode.
234
235o. A new shopt option: localvar_inherit; if set, a local variable inherits the
236 value of a variable with the same name at the nearest preceding scope.
237
238p. `bind -r' now checks whether a key sequence is bound before binding it to
239 NULL, to avoid creating keymaps for a multi-key sequence.
240
241q. A numeric argument to the line editing `operate-and-get-next' command
242 specifies which history entry to use.
243
244r. The positional parameters are now assigned before running the shell startup
245 files, so startup files can use $@.
246
247s. There is a compile-time option that forces the shell to disable the check
248 for an inherited OLDPWD being a directory.
249
250t. The `history' builtin can now delete ranges of history entries using
251 `-d start-end'.
252
253u. The `vi-edit-and-execute-command' bindable readline command now puts readline
254 back in vi insertion mode after executing commands from the edited file.
255
256v. The command completion code now matches aliases and shell function names
257 case-insensitively if the readline completion-ignore-case variable is set.
258
259w. There is a new `assoc_expand_once' shell option that attempts to expand
260 associative array subscripts only once.
261
262x. The shell only sets up BASH_ARGV and BASH_ARGC at startup if extended
263 debugging mode is active. The old behavior of unconditionally setting them
264 is available as part of the shell compatibility options.
265
266y. The `umask' builtin now allows modes and masks greater than octal 777.
267
268z. The `times' builtin now honors the current locale when printing a decimal
269 point.
270
271aa. There is a new (disabled by default, undocumented) shell option to enable
272 and disable sending history to syslog at runtime.
273
274bb. Bash no longer allows variable assignments preceding a special builtin that
275 changes variable attributes to propagate back to the calling environment
276 unless the compatibility level is 44 or lower.
277
278cc. You can set the default value for $HISTSIZE at build time in config-top.h.
279
280dd. The `complete' builtin now accepts a -I option that applies the completion
281 to the initial word on the line.
282
283ee. The internal bash malloc now uses mmap (if available) to satisfy requests
284 greater than 128K bytes, so free can use mfree to return the pages to the
285 kernel.
286
287ff. The shell doesn't automatically set BASH_ARGC and BASH_ARGV at startup
288 unless it's in debugging mode, as the documentation has always said, but
289 will dynamically create them if a script references them at the top level
290 without having enabled debugging mode.
291
292gg. The localvar_inherit option will not attempt to inherit a value from a
293 variable of an incompatible type (indexed vs. associative arrays, for
294 example).
295
296hh. The `globasciiranges' option is now enabled by default; it can be set to
297 off by default at configuration time.
298
299ii. Associative and indexed arrays now allow subscripts consisting solely of
300 whitespace.
301
302jj. `checkwinsize' is now enabled by default.
303
304kk. The `localvar_unset' shopt option is now visible and documented.
305
306ll. The `progcomp_alias' shopt option is now visible and documented.
307
308mm. The signal name processing code now understands `SIGRTMIN+n' all the way
309 up to SIGRTMAX.
310
311nn. There is a new `seq' loadable builtin.
312
313oo. Trap execution now honors the (internal) max invocations of `eval', since
314 traps are supposed to be executed as if using `eval'.
315
316pp. The $_ variable doesn't change when the shell executes a command that forks.
317
318qq. The `kill' builtin now supports -sSIGNAME and -nSIGNUM, even though
319 conforming applications aren't supposed to use them.
320
321rr. POSIX mode now enables the `shift_verbose' option.
322
3232. New Features in Readline
324
325a. Non-incremental vi-mode search (`N', `n') can search for a shell pattern, as
326 Posix specifies (uses fnmatch(3) if available).
327
328b. There are new `next-screen-line' and `previous-screen-line' bindable
329 commands, which move the cursor to the same column in the next, or previous,
330 physical line, respectively.
331
332c. There are default key bindings for control-arrow-key key combinations.
333
334d. A negative argument (-N) to `quoted-insert' means to insert the next N
335 characters using quoted-insert.
336
337e. New public function: rl_check_signals(), which allows applications to
338 respond to signals that readline catches while waiting for input using
339 a custom read function.
340
341f. There is new support for conditionally testing the readline version in an
342 inputrc file, with a full set of arithmetic comparison operators available.
343
344g. There is a simple variable comparison facility available for use within an
345 inputrc file. Allowable operators are equality and inequality; string
346 variables may be compared to a value; boolean variables must be compared to
347 either `on' or `off'; variable names are separated from the operator by
348 whitespace.
349
350h. The history expansion library now understands command and process
351 substitution and extended globbing and allows them to appear anywhere in a
352 word.
353
354i. The history library has a new variable that allows applications to set the
355 initial quoting state, so quoting state can be inherited from a previous
356 line.
357
358j. Readline now allows application-defined keymap names; there is a new public
359 function, rl_set_keymap_name(), to do that.
360
361k. The "Insert" keypad key, if available, now puts readline into overwrite
362 mode.
363
364-------------------------------------------------------------------------------
365This is a terse description of the new features added to bash-4.4 since
366the release of bash-4.3. As always, the manual page (doc/bash.1) is
367the place to look for complete descriptions.
368
3691. New Features in Bash
370
371a. There is now a settable configuration #define that will cause the shell
372 to exit if the shell is running setuid without the -p option and setuid
373 to the real uid fails.
374
375b. Command and process substitutions now turn off the `-v' option when
376 executing, as other shells seem to do.
377
378c. The default value for the `checkhash' shell option may now be set at
379 compile time with a #define.
380
381d. The `mapfile' builtin now has a -d option to use an arbitrary character
382 as the record delimiter, and a -t option to strip the delimiter as
383 supplied with -d.
384
385e. The maximum number of nested recursive calls to `eval' is now settable in
386 config-top.h; the default is no limit.
387
388f. The `-p' option to declare and similar builtins will display attributes for
389 named variables even when those variables have not been assigned values
390 (which are technically unset).
391
392g. The maximum number of nested recursive calls to `source' is now settable
393 in config-top.h; the default is no limit.
394
395h. All builtin commands recognize the `--help' option and print a usage
396 summary.
397
398i. Bash does not allow function names containing `/' and `=' to be exported.
399
400j. The `ulimit' builtin has new -k (kqueues) and -P (pseudoterminals) options.
401
402k. The shell now allows `time ; othercommand' to time null commands.
403
404l. There is a new `--enable-function-import' configuration option to allow
405 importing shell functions from the environment; import is enabled by
406 default.
407
408m. `printf -v var ""' will now set `var' to the empty string, as if `var=""'
409 had been executed.
410
411n. GLOBIGNORE, the pattern substitution word expansion, and programmable
412 completion match filtering now honor the value of the `nocasematch' option.
413
414o. There is a new ${parameter@spec} family of operators to transform the
415 value of `parameter'.
416
417p. Bash no longer attempts to perform compound assignment if a variable on the
418 rhs of an assignment statement argument to `declare' has the form of a
419 compound assignment (e.g., w='(word)' ; declare foo=$w); compound
420 assignments are accepted if the variable was already declared as an array,
421 but with a warning.
422
423q. The declare builtin no longer displays array variables using the compound
424 assignment syntax with quotes; that will generate warnings when re-used as
425 input, and isn't necessary.
426
427r. Executing the rhs of && and || will no longer cause the shell to fork if
428 it's not necessary.
429
430s. The `local' builtin takes a new argument: `-', which will cause it to save
431 and the single-letter shell options and restore their previous values at
432 function return.
433
434t. `complete' and `compgen' have a new `-o nosort' option, which forces
435 readline to not sort the completion matches.
436
437u. Bash now allows waiting for the most recent process substitution, since it
438 appears as $!.
439
440v. The `unset' builtin now unsets a scalar variable if it is subscripted with
441 a `0', analogous to the ${var[0]} expansion.
442
443w. `set -i' is no longer valid, as in other shells.
444
445x. BASH_SUBSHELL is now updated for process substitution and group commands
446 in pipelines, and is available with the same value when running any exit
447 trap.
448
449y. Bash now checks $INSIDE_EMACS as well as $EMACS when deciding whether or
450 not bash is being run in a GNU Emacs shell window.
451
452z. Bash now treats SIGINT received when running a non-builtin command in a
453 loop the way it has traditionally treated running a builtin command:
454 running any trap handler and breaking out of the loop.
455
456aa. New variable: EXECIGNORE; a colon-separate list of patterns that will
457 cause matching filenames to be ignored when searching for commands.
458
459bb. Aliases whose value ends in a shell metacharacter now expand in a way to
460 allow them to be `pasted' to the next token, which can potentially change
461 the meaning of a command (e.g., turning `&' into `&&').
462
463cc. `make install' now installs the example loadable builtins and a set of
464 bash headers to use when developing new loadable builtins.
465
466dd. `enable -f' now attempts to call functions named BUILTIN_builtin_load when
467 loading BUILTIN, and BUILTIN_builtin_unload when deleting it. This allows
468 loadable builtins to run initialization and cleanup code.
469
470ee. There is a new BASH_LOADABLES_PATH variable containing a list of directories
471 where the `enable -f' command looks for shared objects containing loadable
472 builtins.
473
474ff. The `complete_fullquote' option to `shopt' changes filename completion to
475 quote all shell metacharacters in filenames and directory names.
476
477gg. The `kill' builtin now has a `-L' option, equivalent to `-l', for
478 compatibility with Linux standalone versions of kill.
479
480hh. BASH_COMPAT and FUNCNEST can be inherited and set from the shell's initial
481 environment.
482
483ii. inherit_errexit: a new `shopt' option that, when set, causes command
484 substitutions to inherit the -e option. By default, those subshells disable
485 -e. It's enabled as part of turning on posix mode.
486
487jj. New prompt string: PS0. Expanded and displayed by interactive shells after
488 reading a complete command but before executing it.
489
490kk. Interactive shells now behave as if SIGTSTP/SIGTTIN/SIGTTOU are set to
491 SIG_DFL when the shell is started, so they are set to SIG_DFL in child
492 processes.
493
494ll. Posix-mode shells now allow double quotes to quote the history expansion
495 character.
496
497mm. OLDPWD can be inherited from the environment if it names a directory.
498
499nn. Shells running as root no longer inherit PS4 from the environment, closing
500 a security hole involving PS4 expansion performing command substitution.
501
502oo. If executing an implicit `cd' when the `autocd' option is set, bash will
503 now invoke a function named `cd' if one exists before executing the `cd'
504 builtin.
505
506pp. Value conversions (arithmetic expansions, case modification, etc.) now
507 happen when assigning elements of an array using compound assignment.
508
509qq. There is a new option settable in config-top.h that makes multiple
510 directory arguments to `cd' a fatal error.
511
512rr. Bash now uses mktemp() when creating internal temporary files; it produces
513 a warning at build time on many Linux systems.
514
5152. New Features in Readline
516
517a. The history truncation code now uses the same error recovery mechanism as
518 the history writing code, and restores the old version of the history file
519 on error. The error recovery mechanism handles symlinked history files.
520
521b. There is a new bindable variable, `enable-bracketed-paste', which enables
522 support for a terminal's bracketed paste mode.
523
524c. The editing mode indicators can now be strings and are user-settable
525 (new `emacs-mode-string', `vi-cmd-mode-string' and `vi-ins-mode-string'
526 variables). Mode strings can contain invisible character sequences.
527 Setting mode strings to null strings restores the defaults.
528
529d. Prompt expansion adds the mode string to the last line of a multi-line
530 prompt (one with embedded newlines).
531
532e. There is a new bindable variable, `colored-completion-prefix', which, if
533 set, causes the common prefix of a set of possible completions to be
534 displayed in color.
535
536f. There is a new bindable command `vi-yank-pop', a vi-mode version of emacs-
537 mode yank-pop.
538
539g. The redisplay code underwent several efficiency improvements for multibyte
540 locales.
541
542h. The insert-char function attempts to batch-insert all pending typeahead
543 that maps to self-insert, as long as it is coming from the terminal.
544
545i. rl_callback_sigcleanup: a new application function that can clean up and
546 unset any state set by readline's callback mode. Intended to be used
547 after a signal.
548
549j. If an incremental search string has its last character removed with DEL, the
550 resulting empty search string no longer matches the previous line.
551
552k. If readline reads a history file that begins with `#' (or the value of
553 the history comment character) and has enabled history timestamps, the
554 history entries are assumed to be delimited by timestamps. This allows
555 multi-line history entries.
556
557l. Readline now throws an error if it parses a key binding without a
558 terminating `:' or whitespace.
559
560m. The default binding for ^W in vi mode now uses word boundaries specified
561 by Posix (vi-unix-word-rubout is bindable command name).
562
563n. rl_clear_visible_line: new application-callable function; clears all
564 screen lines occupied by the current visible readline line.
565
566o. rl_tty_set_echoing: application-callable function that controls whether
567 or not readline thinks it is echoing terminal output.
568
569p. Handle >| and strings of digits preceding and following redirection
570 specifications as single tokens when tokenizing the line for history
571 expansion.
572
573q. Fixed a bug with displaying completions when the prefix display length
574 is greater than the length of the completions to be displayed.
575
576r. The :p history modifier now applies to the entire line, so any expansion
577 specifying :p causes the line to be printed instead of expanded.
578
579s. New application-callable function: rl_pending_signal(): returns the signal
580 number of any signal readline has caught but not yet handled.
581
582t. New application-settable variable: rl_persistent_signal_handlers: if set
583 to a non-zero value, readline will enable the readline-6.2 signal handler
584 behavior in callback mode: handlers are installed when
585 rl_callback_handler_install is called and removed removed when a complete
586 line has been read.
587
588-------------------------------------------------------------------------------
589This is a terse description of the new features added to bash-4.3 since
590the release of bash-4.2. As always, the manual page (doc/bash.1) is
591the place to look for complete descriptions.
592
5931. New Features in Bash
594
595a. The `helptopic' completion action now maps to all the help topics, not just
596 the shell builtins.
597
598b. The `help' builtin no longer does prefix substring matching first, so
599 `help read' does not match `readonly', but will do it if exact string
600 matching fails.
601
602c. The shell can be compiled to not display a message about processes that
603 terminate due to SIGTERM.
604
605d. Non-interactive shells now react to the setting of checkwinsize and set
606 LINES and COLUMNS after a foreground job exits.
607
608e. There is a new shell option, `globasciiranges', which, when set to on,
609 forces globbing range comparisons to use character ordering as if they
610 were run in the C locale.
611
612f. There is a new shell option, `direxpand', which makes filename completion
613 expand variables in directory names in the way bash-4.1 did.
614
615g. In Posix mode, the `command' builtin does not change whether or not a
616 builtin it shadows is treated as an assignment builtin.
617
618h. The `return' and `exit' builtins accept negative exit status arguments.
619
620i. The word completion code checks whether or not a filename containing a
621 shell variable expands to a directory name and appends `/' to the word
622 as appropriate. The same code expands shell variables in command names
623 when performing command completion.
624
625j. In Posix mode, it is now an error to attempt to define a shell function
626 with the same name as a Posix special builtin.
627
628k. When compiled for strict Posix conformance, history expansion is disabled
629 by default.
630
631l. The history expansion character (!) does not cause history expansion when
632 followed by the closing quote in a double-quoted string.
633
634m. `complete' and its siblings compgen/compopt now takes a new `-o noquote'
635 option to inhibit quoting of the completions.
636
637n. Setting HISTSIZE to a value less than zero causes the history list to be
638 unlimited (setting it 0 zero disables the history list).
639
640o. Setting HISTFILESIZE to a value less than zero causes the history file size
641 to be unlimited (setting it to 0 causes the history file to be truncated
642 to zero size).
643
644p. The `read' builtin now skips NUL bytes in the input.
645
646q. There is a new `bind -X' option to print all key sequences bound to Unix
647 commands.
648
649r. When in Posix mode, `read' is interruptible by a trapped signal. After
650 running the trap handler, read returns 128+signal and throws away any
651 partially-read input.
652
653s. The command completion code skips whitespace and assignment statements
654 before looking for the command name word to be completed.
655
656t. The build process has a new mechanism for constructing separate help files
657 that better reflects the current set of compilation options.
658
659u. The -nt and -ot options to test now work with files with nanosecond
660 timestamp resolution.
661
662v. The shell saves the command history in any shell for which history is
663 enabled and HISTFILE is set, not just interactive shells.
664
665w. The shell has `nameref' variables and new -n(/+n) options to declare and
666 unset to use them, and a `test -R' option to test for them.
667
668x. The shell now allows assigning, referencing, and unsetting elements of
669 indexed arrays using negative subscripts (a[-1]=2, echo ${a[-1]}) which
670 count back from the last element of the array.
671
672y. The {x}<word redirection feature now allows words like {array[ind]} and
673 can use variables with special meanings to the shell (e.g., BASH_XTRACEFD).
674
675z. There is a new CHILD_MAX special shell variable; its value controls the
676 number of exited child statues the shell remembers.
677
678aa. There is a new configuration option (--enable-direxpand-default) that
679 causes the `direxpand' shell option to be enabled by default.
680
681bb. Bash does not do anything special to ensure that the file descriptor
682 assigned to X in {x}<foo remains open after the block containing it
683 completes.
684
685cc. The `wait' builtin has a new `-n' option to wait for the next child to
686 change status.
687
688dd. The `printf' %(...)T format specifier now uses the current time if no
689 argument is supplied.
690
691ee. There is a new variable, BASH_COMPAT, that controls the current shell
692 compatibility level.
693
694ff. The `popd' builtin now treats additional arguments as errors.
695
696gg. The brace expansion code now treats a failed sequence expansion as a
697 simple string and will continue to expand brace terms in the remainder
698 of the word.
699
700hh. Shells started to run process substitutions now run any trap set on EXIT.
701
702ii. The fc builtin now interprets -0 as the current command line.
703
704jj. Completing directory names containing shell variables now adds a trailing
705 slash if the expanded result is a directory.
706
707kk. `cd' has a new `-@' option to browse a file's extended attributes on
708 systems that support O_XATTR.
709
710ll. The test/[/[[ `-v variable' binary operator now understands array
711 references.
712
7132. New Features in Readline
714
715a. Readline is now more responsive to SIGHUP and other fatal signals when
716 reading input from the terminal or performing word completion but no
717 longer attempts to run any not-allowable functions from a signal handler
718 context.
719
720b. There are new bindable commands to search the history for the string of
721 characters between the beginning of the line and the point
722 (history-substring-search-forward, history-substring-search-backward)
723
724c. Readline allows quoted strings as the values of variables when setting
725 them with `set'. As a side effect, trailing spaces and tabs are ignored
726 when setting a string variable's value.
727
728d. The history library creates a backup of the history file when writing it
729 and restores the backup on a write error.
730
731e. New application-settable variable: rl_filename_stat_hook: a function called
732 with a filename before using it in a call to stat(2). Bash uses it to
733 expand shell variables so things like $HOME/Downloads have a slash
734 appended.
735
736f. New bindable function `print-last-kbd-macro', prints the most-recently-
737 defined keyboard macro in a reusable format.
738
739g. New user-settable variable `colored-stats', enables use of colored text
740 to denote file types when displaying possible completions (colored analog
741 of visible-stats).
742
743h. New user-settable variable `keyseq-timout', acts as an inter-character
744 timeout when reading input or incremental search strings.
745
746i. New application-callable function: rl_clear_history. Clears the history list
747 and frees all readline-associated private data.
748
749j. New user-settable variable, show-mode-in-prompt, adds a characters to the
750 beginning of the prompt indicating the current editing mode.
751
752k. New application-settable variable: rl_input_available_hook; function to be
753 called when readline detects there is data available on its input file
754 descriptor.
755
756l. Readline calls an application-set event hook (rl_event_hook) after it gets
757 a signal while reading input (read returns -1/EINTR but readline does not
758 handle the signal immediately) to allow the application to handle or
759 otherwise note it.
760
761m. If the user-settable variable `history-size' is set to a value less than
762 0, the history list size is unlimited.
763
764n. New application-settable variable: rl_signal_event_hook; function that is
765 called when readline is reading terminal input and read(2) is interrupted
766 by a signal. Currently not called for SIGHUP or SIGTERM.
767
768o. rl_change_environment: new application-settable variable that controls
769 whether or not Readline modifies the environment (currently readline
770 modifies only LINES and COLUMNS).
771
772-------------------------------------------------------------------------------
773This is a terse description of the new features added to bash-4.2 since
774the release of bash-4.1. As always, the manual page (doc/bash.1) is
775the place to look for complete descriptions.
776
7771. New Features in Bash
778
779a. `exec -a foo' now sets $0 to `foo' in an executable shell script without a
780 leading #!.
781
782b. Subshells begun to execute command substitutions or run shell functions or
783 builtins in subshells do not reset trap strings until a new trap is
784 specified. This allows $(trap) to display the caller's traps and the
785 trap strings to persist until a new trap is set.
786
787c. `trap -p' will now show signals ignored at shell startup, though their
788 disposition still cannot be modified.
789
790d. $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences.
791
792e. declare/typeset has a new `-g' option, which creates variables in the
793 global scope even when run in a shell function.
794
795f. test/[/[[ have a new -v variable unary operator, which returns success if
796 `variable' has been set.
797
798g. Posix parsing changes to allow `! time command' and multiple consecutive
799 instances of `!' (which toggle) and `time' (which have no cumulative
800 effect).
801
802h. Posix change to allow `time' as a command by itself to print the elapsed
803 user, system, and real times for the shell and its children.
804
805j. $((...)) is always parsed as an arithmetic expansion first, instead of as
806 a potential nested command substitution, as Posix requires.
807
808k. A new FUNCNEST variable to allow the user to control the maximum shell
809 function nesting (recursive execution) level.
810
811l. The mapfile builtin now supplies a third argument to the callback command:
812 the line about to be assigned to the supplied array index.
813
814m. The printf builtin has a new %(fmt)T specifier, which allows time values
815 to use strftime-like formatting.
816
817n. There is a new `compat41' shell option.
818
819o. The cd builtin has a new Posix-mandated `-e' option.
820
821p. Negative subscripts to indexed arrays, previously errors, now are treated
822 as offsets from the maximum assigned index + 1.
823
824q. Negative length specifications in the ${var:offset:length} expansion,
825 previously errors, are now treated as offsets from the end of the variable.
826
827r. Parsing change to allow `time -p --'.
828
829s. Posix-mode parsing change to not recognize `time' as a keyword if the
830 following token begins with a `-'. This means no more Posix-mode
831 `time -p'. Posix interpretation 267.
832
833t. There is a new `lastpipe' shell option that runs the last command of a
834 pipeline in the current shell context. The lastpipe option has no
835 effect if job control is enabled.
836
837u. History expansion no longer expands the `$!' variable expansion.
838
839v. Posix mode shells no longer exit if a variable assignment error occurs
840 with an assignment preceding a command that is not a special builtin.
841
842w. Non-interactive mode shells exit if -u is enabled and an attempt is made
843 to use an unset variable with the % or # expansions, the `//', `^', or
844 `,' expansions, or the parameter length expansion.
845
846x. Posix-mode shells use the argument passed to `.' as-is if a $PATH search
847 fails, effectively searching the current directory. Posix-2008 change.
848
8492. New Features in Readline
850
851a. The history library does not try to write the history filename in the
852 current directory if $HOME is unset. This closes a potential security
853 problem if the application does not specify a history filename.
854
855b. New bindable variable `completion-display-width' to set the number of
856 columns used when displaying completions.
857
858c. New bindable variable `completion-case-map' to cause case-insensitive
859 completion to treat `-' and `_' as identical.
860
861d. There are new bindable vi-mode command names to avoid readline's case-
862 insensitive matching not allowing them to be bound separately.
863
864e. New bindable variable `menu-complete-display-prefix' causes the menu
865 completion code to display the common prefix of the possible completions
866 before cycling through the list, instead of after.
867
868-------------------------------------------------------------------------------
869This is a terse description of the new features added to bash-4.1 since
870the release of bash-4.0. As always, the manual page (doc/bash.1) is
871the place to look for complete descriptions.
872
8731. New Features in Bash
874
875a. Here-documents within $(...) command substitutions may once more be
876 delimited by the closing right paren, instead of requiring a newline.
877
878b. Bash's file status checks (executable, readable, etc.) now take file
879 system ACLs into account on file systems that support them.
880
881c. Bash now passes environment variables with names that are not valid
882 shell variable names through into the environment passed to child
883 processes.
884
885d. The `execute-unix-command' readline function now attempts to clear and
886 reuse the current line rather than move to a new one after the command
887 executes.
888
889e. `printf -v' can now assign values to array indices.
890
891f. New `complete -E' and `compopt -E' options that work on the "empty"
892 completion: completion attempted on an empty command line.
893
894g. New complete/compgen/compopt -D option to define a `default' completion:
895 a completion to be invoked on command for which no completion has been
896 defined. If this function returns 124, programmable completion is
897 attempted again, allowing a user to dynamically build a set of completions
898 as completion is attempted by having the default completion function
899 install individual completion functions each time it is invoked.
900
901h. When displaying associative arrays, subscripts are now quoted.
902
903i. Changes to dabbrev-expand to make it more `emacs-like': no space appended
904 after matches, completions are not sorted, and most recent history entries
905 are presented first.
906
907j. The [[ and (( commands are now subject to the setting of `set -e' and the
908 ERR trap.
909
910k. The source/. builtin now removes NUL bytes from the file before attempting
911 to parse commands.
912
913l. There is a new configuration option (in config-top.h) that forces bash to
914 forward all history entries to syslog.
915
916m. A new variable $BASHOPTS to export shell options settable using `shopt' to
917 child processes.
918
919n. There is a new confgure option that forces the extglob option to be
920 enabled by default.
921
922o. New variable $BASH_XTRACEFD; when set to an integer bash will write xtrace
923 output to that file descriptor.
924
925p. If the optional left-hand-side of a redirection is of the form {var}, the
926 shell assigns the file descriptor used to $var or uses $var as the file
927 descriptor to move or close, depending on the redirection operator.
928
929q. The < and > operators to the [[ conditional command now do string
930 comparison according to the current locale if the compatibility level
931 is greater than 40.
932
933r. Programmable completion now uses the completion for `b' instead of `a'
934 when completion is attempted on a line like: a $(b c.
935
936s. Force extglob on temporarily when parsing the pattern argument to
937 the == and != operators to the [[ command, for compatibility.
938
939t. Changed the behavior of interrupting the wait builtin when a SIGCHLD is
940 received and a trap on SIGCHLD is set to be Posix-mode only.
941
942u. The read builtin has a new `-N nchars' option, which reads exactly NCHARS
943 characters, ignoring delimiters like newline.
944
945v. The mapfile/readarray builtin no longer stores the commands it invokes via
946 callbacks in the history list.
947
948w. There is a new `compat40' shopt option.
949
9502. New Features in Readline
951
952a. New bindable function: menu-complete-backward.
953
954b. In the vi insertion keymap, C-n is now bound to menu-complete by default,
955 and C-p to menu-complete-backward.
956
957c. When in vi command mode, repeatedly hitting ESC now does nothing, even
958 when ESC introduces a bound key sequence. This is closer to how
959 historical vi behaves.
960
961d. New bindable function: skip-csi-sequence. Can be used as a default to
962 consume key sequences generated by keys like Home and End without having
963 to bind all keys.
964
965e. New application-settable function: rl_filename_rewrite_hook. Can be used
966 to rewite or modify filenames read from the file system before they are
967 compared to the word to be completed.
968
969f. New bindable variable: skip-completed-text, active when completing in the
970 middle of a word. If enabled, it means that characters in the completion
971 that match characters in the remainder of the word are "skipped" rather
972 than inserted into the line.
973
974g. The pre-readline-6.0 version of menu completion is available as
975 "old-menu-complete" for users who do not like the readline-6.0 version.
976
977h. New bindable variable: echo-control-characters. If enabled, and the
978 tty ECHOCTL bit is set, controls the echoing of characters corresponding
979 to keyboard-generated signals.
980
981i. New bindable variable: enable-meta-key. Controls whether or not readline
982 sends the smm/rmm sequences if the terminal indicates it has a meta key
983 that enables eight-bit characters.
984
985-------------------------------------------------------------------------------
986This is a terse description of the new features added to bash-4.0 since
987the release of bash-3.2. As always, the manual page (doc/bash.1) is
988the place to look for complete descriptions.
989
9901. New Features in Bash
991
992a. When using substring expansion on the positional parameters, a starting
993 index of 0 now causes $0 to be prefixed to the list.
994
995b. The `help' builtin now prints its columns with entries sorted vertically
996 rather than horizontally.
997
998c. There is a new variable, $BASHPID, which always returns the process id of
999 the current shell.
1000
1001d. There is a new `autocd' option that, when enabled, causes bash to attempt
1002 to `cd' to a directory name that is supplied as the first word of a
1003 simple command.
1004
1005e. There is a new `checkjobs' option that causes the shell to check for and
1006 report any running or stopped jobs at exit.
1007
1008f. The programmable completion code exports a new COMP_TYPE variable, set to
1009 a character describing the type of completion being attempted.
1010
1011g. The programmable completion code exports a new COMP_KEY variable, set to
1012 the character that caused the completion to be invoked (e.g., TAB).
1013
1014h. If creation of a child process fails due to insufficient resources, bash
1015 will try again several times before reporting failure.
1016
1017i. The programmable completion code now uses the same set of characters as
1018 readline when breaking the command line into a list of words.
1019
1020j. The block multiplier for the ulimit -c and -f options is now 512 when in
1021 Posix mode, as Posix specifies.
1022
1023k. Changed the behavior of the read builtin to save any partial input received
1024 in the specified variable when the read builtin times out. This also
1025 results in variables specified as arguments to read to be set to the empty
1026 string when there is no input available. When the read builtin times out,
1027 it returns an exit status greater than 128.
1028
1029l. The shell now has the notion of a `compatibility level', controlled by
1030 new variables settable by `shopt'. Setting this variable currently
1031 restores the bash-3.1 behavior when processing quoted strings on the rhs
1032 of the `=~' operator to the `[[' command.
1033
1034m. The `ulimit' builtin now has new -b (socket buffer size) and -T (number
1035 of threads) options.
1036
1037n. The -p option to `declare' now displays all variable values and attributes
1038 (or function values and attributes if used with -f).
1039
1040o. There is a new `compopt' builtin that allows completion functions to modify
1041 completion options for existing completions or the completion currently
1042 being executed.
1043
1044p. The `read' builtin has a new -i option which inserts text into the reply
1045 buffer when using readline.
1046
1047q. A new `-E' option to the complete builtin allows control of the default
1048 behavior for completion on an empty line.
1049
1050r. There is now limited support for completing command name words containing
1051 globbing characters.
1052
1053s. Changed format of internal help documentation for all builtins to roughly
1054 follow man page format.
1055
1056t. The `help' builtin now has a new -d option, to display a short description,
1057 and a -m option, to print help information in a man page-like format.
1058
1059u. There is a new `mapfile' builtin to populate an array with lines from a
1060 given file. The name `readarray' is a synonym.
1061
1062v. If a command is not found, the shell attempts to execute a shell function
1063 named `command_not_found_handle', supplying the command words as the
1064 function arguments.
1065
1066w. There is a new shell option: `globstar'. When enabled, the globbing code
1067 treats `**' specially -- it matches all directories (and files within
1068 them, when appropriate) recursively.
1069
1070x. There is a new shell option: `dirspell'. When enabled, the filename
1071 completion code performs spelling correction on directory names during
1072 completion.
1073
1074y. The `-t' option to the `read' builtin now supports fractional timeout
1075 values.
1076
1077z. Brace expansion now allows zero-padding of expanded numeric values and
1078 will add the proper number of zeroes to make sure all values contain the
1079 same number of digits.
1080
1081aa. There is a new bash-specific bindable readline function: `dabbrev-expand'.
1082 It uses menu completion on a set of words taken from the history list.
1083
1084bb. The command assigned to a key sequence with `bind -x' now sets two new
1085 variables in the environment of the executed command: READLINE_LINE_BUFFER
1086 and READLINE_POINT. The command can change the current readline line
1087 and cursor position by modifying READLINE_LINE_BUFFER and READLINE_POINT,
1088 respectively.
1089
1090cc. There is a new &>> redirection operator, which appends the standard output
1091 and standard error to the named file.
1092
1093dd. The parser now understands `|&' as a synonym for `2>&1 |', which redirects
1094 the standard error for a command through a pipe.
1095
1096ee. The new `;&' case statement action list terminator causes execution to
1097 continue with the action associated with the next pattern in the
1098 statement rather than terminating the command.
1099
1100ff. The new `;;&' case statement action list terminator causes the shell to
1101 test the next set of patterns after completing execution of the current
1102 action, rather than terminating the command.
1103
1104gg. The shell understands a new variable: PROMPT_DIRTRIM. When set to an
1105 integer value greater than zero, prompt expansion of \w and \W will
1106 retain only that number of trailing pathname components and replace
1107 the intervening characters with `...'.
1108
1109hh. There are new case-modifying word expansions: uppercase (^[^]) and
1110 lowercase (,[,]). They can work on either the first character or
1111 array element, or globally. They accept an optional shell pattern
1112 that determines which characters to modify. There is an optionally-
1113 configured feature to include capitalization operators.
1114
1115ii. The shell provides associative array variables, with the appropriate
1116 support to create, delete, assign values to, and expand them.
1117
1118jj. The `declare' builtin now has new -l (convert value to lowercase upon
1119 assignment) and -u (convert value to uppercase upon assignment) options.
1120 There is an optionally-configurable -c option to capitalize a value at
1121 assignment.
1122
1123kk. There is a new `coproc' reserved word that specifies a coprocess: an
1124 asynchronous command run with two pipes connected to the creating shell.
1125 Coprocs can be named. The input and output file descriptors and the
1126 PID of the coprocess are available to the calling shell in variables
1127 with coproc-specific names.
1128
1129ll. A value of 0 for the -t option to `read' now returns success if there is
1130 input available to be read from the specified file descriptor.
1131
1132mm. CDPATH and GLOBIGNORE are ignored when the shell is running in privileged
1133 mode.
1134
1135nn. New bindable readline functions shell-forward-word and shell-backward-word,
1136 which move forward and backward words delimited by shell metacharacters
1137 and honor shell quoting.
1138
1139oo. New bindable readline functions shell-backward-kill-word and shell-kill-word
1140 which kill words backward and forward, but use the same word boundaries
1141 as shell-forward-word and shell-backward-word.
1142
11432. New Features in Readline
1144
1145a. A new variable, rl_sort_completion_matches; allows applications to inhibit
1146 match list sorting (but beware: some things don't work right if
1147 applications do this).
1148
1149b. A new variable, rl_completion_invoking_key; allows applications to discover
1150 the key that invoked rl_complete or rl_menu_complete.
1151
1152c. The functions rl_block_sigint and rl_release_sigint are now public and
1153 available to calling applications who want to protect critical sections
1154 (like redisplay).
1155
1156d. The functions rl_save_state and rl_restore_state are now public and
1157 available to calling applications; documented rest of readline's state
1158 flag values.
1159
1160e. A new user-settable variable, `history-size', allows setting the maximum
1161 number of entries in the history list.
1162
1163f. There is a new implementation of menu completion, with several improvements
1164 over the old; the most notable improvement is a better `completions
1165 browsing' mode.
1166
1167g. The menu completion code now uses the rl_menu_completion_entry_function
1168 variable, allowing applications to provide their own menu completion
1169 generators.
1170
1171h. There is support for replacing a prefix of a pathname with a `...' when
1172 displaying possible completions. This is controllable by setting the
1173 `completion-prefix-display-length' variable. Matches with a common prefix
1174 longer than this value have the common prefix replaced with `...'.
1175
1176i. There is a new `revert-all-at-newline' variable. If enabled, readline will
1177 undo all outstanding changes to all history lines when `accept-line' is
1178 executed.
1179
1180j. If the kernel supports it, readline displays special characters
1181 corresponding to a keyboard-generated signal when the signal is received.
1182
1183-------------------------------------------------------------------------------
1184This is a terse description of the new features added to bash-3.2 since
1185the release of bash-3.1. As always, the manual page (doc/bash.1) is
1186the place to look for complete descriptions.
1187
11881. New Features in Bash
1189
1190a. Changed the parameter pattern replacement functions to not anchor the
1191 pattern at the beginning of the string if doing global replacement - that
1192 combination doesn't make any sense.
1193
1194b. When running in `word expansion only' mode (--wordexp option), inhibit
1195 process substitution.
1196
1197c. Loadable builtins now work on MacOS X 10.[34].
1198
1199d. Shells running in posix mode no longer set $HOME, as POSIX requires.
1200
1201e. The code that checks for binary files being executed as shell scripts now
1202 checks only for NUL rather than any non-printing character.
1203
1204f. Quoting the string argument to the [[ command's =~ operator now forces
1205 string matching, as with the other pattern-matching operators.
1206
12072. New Features in Readline
1208
1209a. Calling applications can now set the keyboard timeout to 0, allowing
1210 poll-like behavior.
1211
1212b. The value of SYS_INPUTRC (configurable at compilation time) is now used as
1213 the default last-ditch startup file.
1214
1215c. The history file reading functions now allow windows-like \r\n line
1216 terminators.
1217
1218-------------------------------------------------------------------------------
1219This is a terse description of the new features added to bash-3.1 since
1220the release of bash-3.0. As always, the manual page (doc/bash.1) is
1221the place to look for complete descriptions.
1222
12231. New Features in Bash
1224
1225a. Bash now understands LC_TIME as a special variable so that time display
1226 tracks the current locale.
1227
1228b. BASH_ARGC, BASH_ARGV, BASH_SOURCE, and BASH_LINENO are no longer created
1229 as `invisible' variables and may not be unset.
1230
1231c. In POSIX mode, if `xpg_echo' option is enabled, the `echo' builtin doesn't
1232 try to interpret any options at all, as POSIX requires.
1233
1234d. The `bg' builtin now accepts multiple arguments, as POSIX seems to specify.
1235
1236e. Fixed vi-mode word completion and glob expansion to perform tilde
1237 expansion.
1238
1239f. The `**' mathematic exponentiation operator is now right-associative.
1240
1241g. The `ulimit' builtin has new options: -i (max number of pending signals),
1242 -q (max size of POSIX message queues), and -x (max number of file locks).
1243
1244h. A bare `%' once again expands to the current job when used as a job
1245 specifier.
1246
1247i. The `+=' assignment operator (append to the value of a string or array) is
1248 now supported for assignment statements and arguments to builtin commands
1249 that accept assignment statements.
1250
1251j. BASH_COMMAND now preserves its value when a DEBUG trap is executed.
1252
1253k. The `gnu_errfmt' option is enabled automatically if the shell is running
1254 in an emacs terminal window.
1255
1256l. New configuration option: --single-help-strings. Causes long help text
1257 to be written as a single string; intended to ease translation.
1258
1259m. The COMP_WORDBREAKS variable now causes the list of word break characters
1260 to be emptied when the variable is unset.
1261
1262n. An unquoted expansion of $* when $IFS is empty now causes the positional
1263 parameters to be concatenated if the expansion doesn't undergo word
1264 splitting.
1265
1266o. Bash now inherits $_ from the environment if it appears there at startup.
1267
1268p. New shell option: nocasematch. If non-zero, shell pattern matching ignores
1269 case when used by `case' and `[[' commands.
1270
1271q. The `printf' builtin takes a new option: -v var. That causes the output
1272 to be placed into var instead of on stdout.
1273
1274r. By default, the shell no longer reports processes dying from SIGPIPE.
1275
1276s. Bash now sets the extern variable `environ' to the export environment it
1277 creates, so C library functions that call getenv() (and can't use the
1278 shell-provided replacement) get current values of environment variables.
1279
1280t. A new configuration option, `--enable-strict-posix-default', which will
1281 build bash to be POSIX conforming by default.
1282
1283u. If compiled for strict POSIX conformance, LINES and COLUMNS may now
1284 override the true terminal size.
1285
12862. New Features in Readline
1287
1288a. The key sequence sent by the keypad `delete' key is now automatically
1289 bound to delete-char.
1290
1291b. A negative argument to menu-complete now cycles backward through the
1292 completion list.
1293
1294c. A new bindable readline variable: bind-tty-special-chars. If non-zero,
1295 readline will bind the terminal special characters to their readline
1296 equivalents when it's called (on by default).
1297
1298d. New bindable command: vi-rubout. Saves deleted text for possible
1299 reinsertion, as with any vi-mode `text modification' command; `X' is bound
1300 to this in vi command mode.
1301
1302e. A new external application-controllable variable that allows the LINES
1303 and COLUMNS environment variables to set the window size regardless of
1304 what the kernel returns: rl_prefer_env_winsize
1305
1306-------------------------------------------------------------------------------
1307This is a terse description of the new features added to bash-3.0 since
1308the release of bash-2.05b. As always, the manual page (doc/bash.1) is
1309the place to look for complete descriptions.
1310
13111. New Features in Bash
1312
1313a. ANSI string expansion now implements the \x{hexdigits} escape.
1314
1315b. There is a new loadable `strftime' builtin.
1316
1317c. New variable, COMP_WORDBREAKS, which controls the readline completer's
1318 idea of word break characters.
1319
1320d. The `type' builtin no longer reports on aliases unless alias expansion
1321 will actually be performed.
1322
1323e. HISTCONTROL is now a colon-separated list of values, which permits
1324 more extensibility and backwards compatibility.
1325
1326f. HISTCONTROL may now include the `erasedups' option, which causes all lines
1327 matching a line being added to be removed from the history list.
1328
1329g. `configure' has a new `--enable-multibyte' argument that permits multibyte
1330 character support to be disabled even on systems that support it.
1331
1332h. New variables to support the bash debugger: BASH_ARGC, BASH_ARGV,
1333 BASH_SOURCE, BASH_LINENO, BASH_SUBSHELL, BASH_EXECUTION_STRING,
1334 BASH_COMMAND
1335
1336i. FUNCNAME has been changed to support the debugger: it's now an array
1337 variable.
1338
1339j. for, case, select, arithmetic commands now keep line number information
1340 for the debugger.
1341
1342k. There is a new `RETURN' trap executed when a function or sourced script
1343 returns (not inherited child processes; inherited by command substitution
1344 if function tracing is enabled and the debugger is active).
1345
1346l. New invocation option: --debugger. Enables debugging and turns on new
1347 `extdebug' shell option.
1348
1349m. New `functrace' and `errtrace' options to `set -o' cause DEBUG and ERR
1350 traps, respectively, to be inherited by shell functions. Equivalent to
1351 `set -T' and `set -E' respectively. The `functrace' option also controls
1352 whether or not the DEBUG trap is inherited by sourced scripts.
1353
1354n. The DEBUG trap is run before binding the variable and running the action
1355 list in a `for' command, binding the selection variable and running the
1356 query in a `select' command, and before attempting a match in a `case'
1357 command.
1358
1359o. New `--enable-debugger' option to `configure' to compile in the debugger
1360 support code.
1361
1362p. `declare -F' now prints out extra line number and source file information
1363 if the `extdebug' option is set.
1364
1365q. If `extdebug' is enabled, a non-zero return value from a DEBUG trap causes
1366 the next command to be skipped, and a return value of 2 while in a
1367 function or sourced script forces a `return'.
1368
1369r. New `caller' builtin to provide a call stack for the bash debugger.
1370
1371s. The DEBUG trap is run just before the first command in a function body is
1372 executed, for the debugger.
1373
1374t. `for', `select', and `case' command heads are printed when `set -x' is
1375 enabled.
1376
1377u. There is a new {x..y} brace expansion, which is shorthand for {x.x+1,
1378 x+2,...,y}. x and y can be integers or single characters; the sequence
1379 may ascend or descend; the increment is always 1.
1380
1381v. New ksh93-like ${!array[@]} expansion, expands to all the keys (indices)
1382 of array.
1383
1384w. New `force_fignore' shopt option; if enabled, suffixes specified by
1385 FIGNORE cause words to be ignored when performing word completion even
1386 if they're the only possibilities.
1387
1388x. New `gnu_errfmt' shopt option; if enabled, error messages follow the `gnu
1389 style' (filename:lineno:message) format.
1390
1391y. New `-o bashdefault' option to complete and compgen; if set, causes the
1392 whole set of bash completions to be performed if the compspec doesn't
1393 result in a match.
1394
1395z. New `-o plusdirs' option to complete and compgen; if set, causes directory
1396 name completion to be performed and the results added to the rest of the
1397 possible completions.
1398
1399aa. `kill' is available as a builtin even when the shell is built without
1400 job control.
1401
1402bb. New HISTTIMEFORMAT variable; value is a format string to pass to
1403 strftime(3). If set and not null, the `history' builtin prints out
1404 timestamp information according to the specified format when displaying
1405 history entries. If set, bash tells the history library to write out
1406 timestamp information when the history file is written.
1407
1408cc. The [[ ... ]] command has a new binary `=~' operator that performs
1409 extended regular expression (egrep-like) matching.
1410
1411dd. `configure' has a new `--enable-cond-regexp' option (enabled by default)
1412 to enable the =~ operator and regexp matching in [[ ... ]].
1413
1414ee. Subexpressions matched by the =~ operator are placed in the new
1415 BASH_REMATCH array variable.
1416
1417ff. New `failglob' option that causes an expansion error when pathname
1418 expansion fails to produce a match.
1419
1420gg. New `set -o pipefail' option that causes a pipeline to return a failure
1421 status if any of the processes in the pipeline fail, not just the last
1422 one.
1423
1424hh. printf builtin understands two new escape sequences: \" and \?.
1425
1426ii. `echo -e' understands two new escape sequences: \" and \?.
1427
1428jj. The GNU `gettext' package and libintl have been integrated; the shell's
1429 messages can be translated into different languages.
1430
1431kk. The `\W' prompt expansion now abbreviates $HOME as `~', like `\w'.
1432
1433ll. The error message printed when bash cannot open a shell script supplied
1434 as argument 1 now includes the name of the shell, to better identify
1435 the error as coming from bash.
1436
1437mm. The parameter pattern removal and substitution expansions are now much
1438 faster and more efficient when using multibyte characters.
1439
1440nn. The `jobs', `kill', and `wait' builtins now accept job control notation
1441 even if job control is not enabled.
1442
1443oo. The historical behavior of `trap' that allows a missing `action' argument
1444 to cause each specified signal's handling to be reset to its default is
1445 now only supported when `trap' is given a single non-option argument.
1446
14472. New Features in Readline
1448
1449a. History expansion has a new `a' modifier equivalent to the `g' modifier
1450 for compatibility with the BSD csh.
1451
1452b. History expansion has a new `G' modifier equivalent to the BSD csh `g'
1453 modifier, which performs a substitution once per word.
1454
1455c. All non-incremental search operations may now undo the operation of
1456 replacing the current line with the history line.
1457
1458d. The text inserted by an `a' command in vi mode can be reinserted with
1459 `.'.
1460
1461e. New bindable variable, `show-all-if-unmodified'. If set, the readline
1462 completer will list possible completions immediately if there is more
1463 than one completion and partial completion cannot be performed.
1464
1465f. There is a new application-callable `free_history_entry()' function.
1466
1467g. History list entries now contain timestamp information; the history file
1468 functions know how to read and write timestamp information associated
1469 with each entry.
1470
1471h. Four new key binding functions have been added:
1472
1473 rl_bind_key_if_unbound()
1474 rl_bind_key_if_unbound_in_map()
1475 rl_bind_keyseq_if_unbound()
1476 rl_bind_keyseq_if_unbound_in_map()
1477
1478i. New application variable, rl_completion_quote_character, set to any
1479 quote character readline finds before it calls the application completion
1480 function.
1481
1482j. New application variable, rl_completion_suppress_quote, settable by an
1483 application completion function. If set to non-zero, readline does not
1484 attempt to append a closing quote to a completed word.
1485
1486k. New application variable, rl_completion_found_quote, set to a non-zero
1487 value if readline determines that the word to be completed is quoted.
1488 Set before readline calls any application completion function.
1489
1490l. New function hook, rl_completion_word_break_hook, called when readline
1491 needs to break a line into words when completion is attempted. Allows
1492 the word break characters to vary based on position in the line.
1493
1494m. New bindable command: unix-filename-rubout. Does the same thing as
1495 unix-word-rubout, but adds `/' to the set of word delimiters.
1496
1497n. When listing completions, directories have a `/' appended if the
1498 `mark-directories' option has been enabled.
1499
1500-------------------------------------------------------------------------------
1501This is a terse description of the new features added to bash-2.05b since
1502the release of bash-2.05a. As always, the manual page (doc/bash.1) is
1503the place to look for complete descriptions.
1504
15051. New Features in Bash
1506
1507a. If set, TMOUT is the default timeout for the `read' builtin.
1508
1509b. `type' has two new options: `-f' suppresses shell function lookup, and
1510 `-P' forces a $PATH search.
1511
1512c. New code to handle multibyte characters.
1513
1514d. `select' was changed to be more ksh-compatible, in that the menu is
1515 reprinted each time through the loop only if REPLY is set to NULL.
1516 The previous behavior is available as a compile-time option.
1517
1518e. `complete -d' and `complete -o dirnames' now force a slash to be
1519 appended to names which are symlinks to directories.
1520
1521f. There is now a bindable edit-and-execute-command readline command,
1522 like the vi-mode `v' command, bound to C-xC-e in emacs mode.
1523
1524g. Added support for ksh93-like [:word:] character class in pattern matching.
1525
1526h. The $'...' quoting construct now expands \cX to Control-X.
1527
1528i. A new \D{...} prompt expansion; passes the `...' to strftime and inserts
1529 the result into the expanded prompt.
1530
1531j. The shell now performs arithmetic in the largest integer size the
1532 machine supports (intmax_t), instead of long.
1533
1534k. If a numeric argument is supplied to one of the bash globbing completion
1535 functions, a `*' is appended to the word before expansion is attempted.
1536
1537l. The bash globbing completion functions now allow completions to be listed
1538 with double tabs or if `show-all-if-ambiguous' is set.
1539
1540m. New `-o nospace' option for `complete' and `compgen' builtins; suppresses
1541 readline's appending a space to the completed word.
1542
1543n. New `here-string' redirection operator: <<< word.
1544
1545o. When displaying variables, function attributes and definitions are shown
1546 separately, allowing them to be re-used as input (attempting to re-use
1547 the old output would result in syntax errors).
1548
1549p. There is a new configuration option `--enable-mem-scramble', controls
1550 bash malloc behavior of writing garbage characters into memory at
1551 allocation and free time.
1552
1553q. The `complete' and `compgen' builtins now have a new `-s/-A service'
1554 option to complete on names from /etc/services.
1555
1556r. `read' has a new `-u fd' option to read from a specified file descriptor.
1557
1558s. Fix the completion code so that expansion errors in a directory name
1559 don't cause a longjmp back to the command loop.
1560
1561t. Fixed word completion inside command substitution to work a little more
1562 intuitively.
1563
1564u. The `printf' %q format specifier now uses $'...' quoting to print the
1565 argument if it contains non-printing characters.
1566
1567v. The `declare' and `typeset' builtins have a new `-t' option. When applied
1568 to functions, it causes the DEBUG trap to be inherited by the named
1569 function. Currently has no effect on variables.
1570
1571w. The DEBUG trap is now run *before* simple commands, ((...)) commands,
1572 [[...]] conditional commands, and for ((...)) loops.
1573
1574x. The expansion of $LINENO inside a shell function is only relative to the
1575 function start if the shell is interactive -- if the shell is running a
1576 script, $LINENO expands to the line number in the script. This is as
1577 POSIX-2001 requires.
1578
1579y. The bash debugger in examples/bashdb has been modified to work with the
1580 new DEBUG trap semantics, the command set has been made more gdb-like,
1581 and the changes to $LINENO make debugging functions work better. Code
1582 from Gary Vaughan.
1583
1584z. New [n]<&word- and [n]>&word- redirections from ksh93 -- move fds (dup
1585 and close).
1586
1587aa. There is a new `-l' invocation option, equivalent to `--login'.
1588
1589bb. The `hash' builtin has a new `-l' option to list contents in a reusable
1590 format, and a `-d' option to remove a name from the hash table.
1591
1592cc. There is now support for placing the long help text into separate files
1593 installed into ${datadir}/bash. Not enabled by default; can be turned
1594 on with `--enable-separate-helpfiles' option to configure.
1595
1596dd. All builtins that take operands accept a `--' pseudo-option, except
1597 `echo'.
1598
1599ee. The `echo' builtin now accepts \0xxx (zero to three octal digits following
1600 the `0') in addition to \xxx (one to three octal digits) for SUSv3/XPG6/
1601 POSIX.1-2001 compliance.
1602
1603
16042. New Features in Readline
1605
1606a. Support for key `subsequences': allows, e.g., ESC and ESC-a to both
1607 be bound to readline functions. Now the arrow keys may be used in vi
1608 insert mode.
1609
1610b. When listing completions, and the number of lines displayed is more than
1611 the screen length, readline uses an internal pager to display the results.
1612 This is controlled by the `page-completions' variable (default on).
1613
1614c. New code to handle editing and displaying multibyte characters.
1615
1616d. The behavior introduced in bash-2.05a of deciding whether or not to
1617 append a slash to a completed name that is a symlink to a directory has
1618 been made optional, controlled by the `mark-symlinked-directories'
1619 variable (default is the 2.05a behavior).
1620
1621e. The `insert-comment' command now acts as a toggle if given a numeric
1622 argument: if the first characters on the line don't specify a
1623 comment, insert one; if they do, delete the comment text
1624
1625f. New application-settable completion variable:
1626 rl_completion_mark_symlink_dirs, allows an application's completion
1627 function to temporarily override the user's preference for appending
1628 slashes to names which are symlinks to directories.
1629
1630g. New function available to application completion functions:
1631 rl_completion_mode, to tell how the completion function was invoked
1632 and decide which argument to supply to rl_complete_internal (to list
1633 completions, etc.).
1634
1635h. Readline now has an overwrite mode, toggled by the `overwrite-mode'
1636 bindable command, which could be bound to `Insert'.
1637
1638i. New application-settable completion variable:
1639 rl_completion_suppress_append, inhibits appending of
1640 rl_completion_append_character to completed words.
1641
1642j. New key bindings when reading an incremental search string: ^W yanks
1643 the currently-matched word out of the current line into the search
1644 string; ^Y yanks the rest of the current line into the search string,
1645 DEL or ^H deletes characters from the search string.
1646
1647-------------------------------------------------------------------------------
1648This is a terse description of the new features added to bash-2.05a since
1649the release of bash-2.05. As always, the manual page (doc/bash.1) is
1650the place to look for complete descriptions.
1651
16521. New Features in Bash
1653
1654a. Added support for DESTDIR installation root prefix, so you can do a
1655 `make install DESTDIR=bash-root' and do easier binary packaging.
1656
1657b. Added support for builtin printf "'" flag character as per latest POSIX
1658 drafts.
1659
1660c. Support for POSIX.2 printf(1) length specifiers `j', `t', and `z' (from
1661 ISO C99).
1662
1663d. New autoconf macro, RL_LIB_READLINE_VERSION, for use by other applications
1664 (bash doesn't use very much of what it returns).
1665
1666e. `set [-+]o nolog' is recognized as required by the latest POSIX drafts,
1667 but ignored.
1668
1669f. New read-only `shopt' option: login_shell. Set to non-zero value if the
1670 shell is a login shell.
1671
1672g. New `\A' prompt string escape sequence; expands to time in 24 HH:MM format.
1673
1674h. New `-A group/-g' option to complete and compgen; does group name
1675 completion.
1676
1677i. New `-t' option to `hash' to list hash values for each filename argument.
1678
1679j. New [-+]O invocation option to set and unset `shopt' options at startup.
1680
1681k. configure's `--with-installed-readline' option now takes an optional
1682 `=PATH' suffix to set the root of the tree where readline is installed
1683 to PATH.
1684
1685l. The ksh-like `ERR' trap has been added. The `ERR' trap will be run
1686 whenever the shell would have exited if the -e option were enabled.
1687 It is not inherited by shell functions.
1688
1689m. `readonly', `export', and `declare' now print variables which have been
1690 given attributes but not set by assigning a value as just a command and
1691 a variable name (like `export foo') when listing, as the latest POSIX
1692 drafts require.
1693
1694n. `bashbug' now requires that the subject be changed from the default.
1695
1696o. configure has a new `--enable-largefile' option, like other GNU utilities.
1697
1698p. `for' loops now allow empty word lists after `in', like the latest POSIX
1699 drafts require.
1700
1701q. The builtin `ulimit' now takes two new non-numeric arguments: `hard',
1702 meaning the current hard limit, and `soft', meaning the current soft
1703 limit, in addition to `unlimited'
1704
1705r. `ulimit' now prints the option letter associated with a particular
1706 resource when printing more than one limit.
1707
1708s. `ulimit' prints `hard' or `soft' when a value is not `unlimited' but is
1709 one of RLIM_SAVED_MAX or RLIM_SAVED_CUR, respectively.
1710
1711t. The `printf' builtin now handles the %a and %A conversions if they're
1712 implemented by printf(3).
1713
1714u. The `printf' builtin now handles the %F conversion (just about like %f).
1715
1716v. The `printf' builtin now handles the %n conversion like printf(3). The
1717 corresponding argument is the name of a shell variable to which the
1718 value is assigned.
1719
17202. New Features in Readline
1721
1722a. Added extern declaration for rl_get_termcap to readline.h, making it a
1723 public function (it was always there, just not in readline.h).
1724
1725b. New #defines in readline.h: RL_READLINE_VERSION, currently 0x0402,
1726 RL_VERSION_MAJOR, currently 4, and RL_VERSION_MINOR, currently 2.
1727
1728c. New readline variable: rl_readline_version, mirrors RL_READLINE_VERSION.
1729
1730d. New bindable boolean readline variable: match-hidden-files. Controls
1731 completion of files beginning with a `.' (on Unix). Enabled by default.
1732
1733e. The history expansion code now allows any character to terminate a
1734 `:first-' modifier, like csh.
1735
1736f. New bindable variable `history-preserve-point'. If set, the history
1737 code attempts to place the user at the same location on each history
1738 line retrieved with previous-history or next-history.
1739
1740-------------------------------------------------------------------------------
1741This is a terse description of the new features added to bash-2.05 since
1742the release of bash-2.04. As always, the manual page (doc/bash.1) is
1743the place to look for complete descriptions.
1744
17451. New Features in Bash
1746
1747a. Added a new `--init-file' invocation argument as a synonym for `--rcfile',
1748 per the new GNU coding standards.
1749
1750b. The /dev/tcp and /dev/udp redirections now accept service names as well as
1751 port numbers.
1752
1753c. `complete' and `compgen' now take a `-o value' option, which controls some
1754 of the aspects of that compspec. Valid values are:
1755
1756 default - perform bash default completion if programmable
1757 completion produces no matches
1758 dirnames - perform directory name completion if programmable
1759 completion produces no matches
1760 filenames - tell readline that the compspec produces filenames,
1761 so it can do things like append slashes to
1762 directory names and suppress trailing spaces
1763
1764d. A new loadable builtin, realpath, which canonicalizes and expands symlinks
1765 in pathname arguments.
1766
1767e. When `set' is called without options, it prints function definitions in a
1768 way that allows them to be reused as input. This affects `declare' and
1769 `declare -p' as well. This only happens when the shell is not in POSIX
1770 mode, since POSIX.2 forbids this behavior.
1771
1772f. Bash-2.05 once again honors the current locale setting when processing
1773 ranges within pattern matching bracket expressions (e.g., [A-Z]).
1774
17752. New Features in Readline
1776
1777a. The blink timeout for paren matching is now settable by applications,
1778 via the rl_set_paren_blink_timeout() function.
1779
1780b. _rl_executing_macro has been renamed to rl_executing_macro, which means
1781 it's now part of the public interface.
1782
1783c. Readline has a new variable, rl_readline_state, which is a bitmap that
1784 encapsulates the current state of the library; intended for use by
1785 callbacks and hook functions.
1786
1787d. New application-callable function rl_set_prompt(const char *prompt):
1788 expands its prompt string argument and sets rl_prompt to the result.
1789
1790e. New application-callable function rl_set_screen_size(int rows, int cols):
1791 public method for applications to set readline's idea of the screen
1792 dimensions.
1793
1794f. New function, rl_get_screen_size (int *rows, int *columns), returns
1795 readline's idea of the screen dimensions.
1796
1797g. The timeout in rl_gather_tyi (readline keyboard input polling function)
1798 is now settable via a function (rl_set_keyboard_input_timeout()).
1799
1800h. Renamed the max_input_history variable to history_max_entries; the old
1801 variable is maintained for backwards compatibility.
1802
1803i. The list of characters that separate words for the history tokenizer is
1804 now settable with a variable: history_word_delimiters. The default
1805 value is as before.
1806
1807-------------------------------------------------------------------------------
1808This is a terse description of the new features added to bash-2.04 since
1809the release of bash-2.03. As always, the manual page (doc/bash.1) is
1810the place to look for complete descriptions.
1811
18121. New Features in Bash
1813
1814a. The history builtin has a `-d offset' option to delete the history entry
1815 at position `offset'.
1816
1817b. The prompt expansion code has two new escape sequences: \j, the number of
1818 active jobs; and \l, the basename of the shell's tty device name.
1819
1820c. The `bind' builtin has a new `-x' option to bind key sequences to shell
1821 commands.
1822
1823d. There is a new shell option, no_empty_command_completion, which, when
1824 enabled, disables command completion when TAB is typed on an empty line.
1825
1826e. The `help' builtin has a `-s' option to just print a builtin's usage
1827 synopsis.
1828
1829f. There are several new arithmetic operators: id++, id-- (variable
1830 post-increment/decrement), ++id, --id (variable pre-increment/decrement),
1831 expr1 , expr2 (comma operator).
1832
1833g. There is a new ksh-93 style arithmetic for command:
1834 for ((expr1 ; expr2; expr3 )); do list; done
1835
1836h. The `read' builtin has a number of new options:
1837 -t timeout only wait timeout seconds for input
1838 -n nchars only read nchars from input instead of a full line
1839 -d delim read until delim rather than newline
1840 -s don't echo input chars as they are read
1841
1842i. The redirection code now handles several filenames specially:
1843 /dev/fd/N, /dev/stdin, /dev/stdout, and /dev/stderr, whether or
1844 not they are present in the file system.
1845
1846j. The redirection code now recognizes pathnames of the form
1847 /dev/tcp/host/port and /dev/udp/host/port, and tries to open a socket
1848 of the appropriate type to the specified port on the specified host.
1849
1850k. The ksh-93 ${!prefix*} expansion, which expands to the names of all
1851 shell variables with prefix PREFIX, has been implemented.
1852
1853l. There is a new dynamic variable, FUNCNAME, which expands to the name of
1854 a currently-executing function. Assignments to FUNCNAME have no effect.
1855
1856m. The GROUPS variable is no longer readonly; assignments to it are silently
1857 discarded. This means it can be unset.
1858
1859n. A new programmable completion facility, with two new builtin commands:
1860 complete and compgen.
1861
1862o. configure has a new option, `--enable-progcomp', to compile in the
1863 programmable completion features (enabled by default).
1864
1865p. `shopt' has a new option, `progcomp', to enable and disable programmable
1866 completion at runtime.
1867
1868q. Unsetting HOSTFILE now clears the list of hostnames used for completion.
1869
1870r. configure has a new option, `--enable-bash-malloc', replacing the old
1871 `--with-gnu-malloc' (which is still present for backwards compatibility).
1872
1873s. There is a new manual page describing rbash, the restricted shell.
1874
1875t. `bashbug' has new `--help' and `--version' options.
1876
1877u. `shopt' has a new `xpg_echo' option, which controls the behavior of
1878 `echo' with respect to backslash-escaped characters at runtime.
1879
1880v. If NON_INTERACTIVE_LOGIN_SHELLS is defined, all login shells read the
1881 startup files, even if they are not interactive.
1882
1883w. The LC_NUMERIC variable is now treated specially, and used to set the
1884 LC_NUMERIC locale category for number formatting, e.g., when `printf'
1885 displays floating-point numbers.
1886
18872. New features in Readline
1888
1889a. Parentheses matching is now always compiled into readline, and enabled
1890 or disabled when the value of the `blink-matching-paren' variable is
1891 changed.
1892
1893b. MS-DOS systems now use ~/_inputrc as the last-ditch inputrc filename.
1894
1895c. MS-DOS systems now use ~/_history as the default history file.
1896
1897d. history-search-{forward,backward} now leave the point at the end of the
1898 line when the string to search for is empty, like
1899 {reverse,forward}-search-history.
1900
1901e. history-search-{forward,backward} now leave the last history line found
1902 in the readline buffer if the second or subsequent search fails.
1903
1904f. New function for use by applications: rl_on_new_line_with_prompt, used
1905 when an application displays the prompt itself before calling readline().
1906
1907g. New variable for use by applications: rl_already_prompted. An application
1908 that displays the prompt itself before calling readline() must set this to
1909 a non-zero value.
1910
1911h. A new variable, rl_gnu_readline_p, always 1. The intent is that an
1912 application can verify whether or not it is linked with the `real'
1913 readline library or some substitute.
1914
1915-------------------------------------------------------------------------------
1916This is a terse description of the new features added to bash-2.03 since
1917the release of bash-2.02. As always, the manual page (doc/bash.1) is
1918the place to look for complete descriptions.
1919
19201. New Features in Bash
1921
1922a. New `shopt' option, `restricted_shell', indicating whether or not the
1923 shell was started in restricted mode, for use in startup files.
1924
1925b. Filename generation is now performed on the words between ( and ) in
1926 array assignments (which it probably should have done all along).
1927
1928c. OLDPWD is now auto-exported, as POSIX.2 seems to require.
1929
1930d. ENV and BASH_ENV are read-only variables in a restricted shell.
1931
1932e. A change was made to the startup file code so that any shell begun with
1933 the `--login' option, even non-interactive shells, will source the login
1934 shell startup files.
1935
19362. New Features in Readline
1937
1938a. Many changes to the signal handling:
1939 o Readline now catches SIGQUIT and cleans up the tty before returning;
1940 o A new variable, rl_catch_signals, is available to application writers
1941 to indicate to readline whether or not it should install its own
1942 signal handlers for SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP,
1943 SIGTTIN, and SIGTTOU;
1944 o A new variable, rl_catch_sigwinch, is available to application
1945 writers to indicate to readline whether or not it should install its
1946 own signal handler for SIGWINCH, which will chain to the calling
1947 applications's SIGWINCH handler, if one is installed;
1948 o There is a new function, rl_free_line_state, for application signal
1949 handlers to call to free up the state associated with the current
1950 line after receiving a signal;
1951 o There is a new function, rl_cleanup_after_signal, to clean up the
1952 display and terminal state after receiving a signal;
1953 o There is a new function, rl_reset_after_signal, to reinitialize the
1954 terminal and display state after an application signal handler
1955 returns and readline continues
1956
1957b. There is a new function, rl_resize_terminal, to reset readline's idea of
1958 the screen size after a SIGWINCH.
1959
1960c. New public functions: rl_save_prompt and rl_restore_prompt. These were
1961 previously private functions with a `_' prefix.
1962
1963d. New function hook: rl_pre_input_hook, called just before readline starts
1964 reading input, after initialization.
1965
1966e. New function hook: rl_display_matches_hook, called when readline would
1967 display the list of completion matches. The new function
1968 rl_display_match_list is what readline uses internally, and is available
1969 for use by application functions called via this hook.
1970
1971f. New bindable function, delete-char-or-list, like tcsh.
1972
1973g. A new variable, rl_erase_empty_line, which, if set by an application using
1974 readline, will cause readline to erase, prompt and all, lines on which the
1975 only thing typed was a newline.
1976
1977h. New bindable variable: `isearch-terminators'.
1978
1979i. New bindable function: `forward-backward-delete-char' (unbound by default).
1980
1981-------------------------------------------------------------------------------
1982This is a terse description of the new features added to bash-2.02 since
1983the release of bash-2.01.1. As always, the manual page (doc/bash.1) is
1984the place to look for complete descriptions.
1985
19861. New Features in Bash
1987
1988a. A new version of malloc, based on the older GNU malloc, that has many
1989 changes, is more page-based, is more conservative with memory usage,
1990 and does not `orphan' large blocks when they are freed.
1991
1992b. A new version of gmalloc, based on the old GLIBC malloc, with many
1993 changes and range checking included by default.
1994
1995c. A new implementation of fnmatch(3) that includes full POSIX.2 Basic
1996 Regular Expression matching, including character classes, collating
1997 symbols, equivalence classes, and support for case-insensitive pattern
1998 matching.
1999
2000d. ksh-88 egrep-style extended pattern matching ([@+*?!](patlist)) has been
2001 implemented, controlled by a new `shopt' option, `extglob'.
2002
2003e. There is a new ksh-like `[[' compound command, which implements
2004 extended `test' functionality.
2005
2006f. There is a new `printf' builtin, implemented according to the POSIX.2
2007 specification.
2008
2009g. There is a new feature for command substitution: $(< filename) now expands
2010 to the contents of `filename', with any trailing newlines removed
2011 (equivalent to $(cat filename)).
2012
2013h. There are new tilde prefixes which expand to directories from the
2014 directory stack.
2015
2016i. There is a new `**' arithmetic operator to do exponentiation.
2017
2018j. There are new configuration options to control how bash is linked:
2019 `--enable-profiling', to allow bash to be profiled with gprof, and
2020 `--enable-static-link', to allow bash to be linked statically.
2021
2022k. There is a new configuration option, `--enable-cond-command', which
2023 controls whether or not the `[[' command is included. It is on by
2024 default.
2025
2026l. There is a new configuration option, `--enable-extended-glob', which
2027 controls whether or not the ksh extended globbing feature is included.
2028 It is enabled by default.
2029
2030m. There is a new configuration #define in config.h.top that, when enabled,
2031 will cause all login shells to source /etc/profile and one of the user-
2032 specific login shell startup files, whether or not the shell is
2033 interactive.
2034
2035n. There is a new invocation option, `--dump-po-strings', to dump
2036 a shell script's translatable strings ($"...") in GNU `po' format.
2037
2038o. There is a new `shopt' option, `nocaseglob', to enable case-insensitive
2039 pattern matching when globbing filenames and using the `case' construct.
2040
2041p. There is a new `shopt' option, `huponexit', which, when enabled, causes
2042 the shell to send SIGHUP to all jobs when an interactive login shell
2043 exits.
2044
2045q. `bind' has a new `-u' option, which takes a readline function name as an
2046 argument and unbinds all key sequences bound to that function in a
2047 specified keymap.
2048
2049r. `disown' now has `-a' and `-r' options, to limit operation to all jobs
2050 and running jobs, respectively.
2051
2052s. The `shopt' `-p' option now causes output to be displayed in a reusable
2053 format.
2054
2055t. `test' has a new `-N' option, which returns true if the filename argument
2056 has been modified since it was last accessed.
2057
2058u. `umask' now has a `-p' option to print output in a reusable format.
2059
2060v. A new escape sequence, `\xNNN', has been added to the `echo -e' and $'...'
2061 translation code. It expands to the character whose ascii code is NNN
2062 in hexadecimal.
2063
2064w. The prompt string expansion code has a new `\r' escape sequence.
2065
2066x. The shell may now be cross-compiled for the CYGWIN32 environment on
2067 a Unix machine.
2068
20692. New Features in Readline
2070
2071a. There is now an option for `iterative' yank-last-arg handline, so a user
2072 can keep entering `M-.', yanking the last argument of successive history
2073 lines.
2074
2075b. New variable, `print-completions-horizontally', which causes completion
2076 matches to be displayed across the screen (like `ls -x') rather than up
2077 and down the screen (like `ls').
2078
2079c. New variable, `completion-ignore-case', which causes filename completion
2080 and matching to be performed case-insensitively.
2081
2082d. There is a new bindable command, `magic-space', which causes history
2083 expansion to be performed on the current readline buffer and a space to
2084 be inserted into the result.
2085
2086e. There is a new bindable command, `menu-complete', which enables tcsh-like
2087 menu completion (successive executions of menu-complete insert a single
2088 completion match, cycling through the list of possible completions).
2089
2090f. There is a new bindable command, `paste-from-clipboard', for use on Win32
2091 systems, to insert the text from the Win32 clipboard into the editing
2092 buffer.
2093
2094g. The key sequence translation code now understands printf-style backslash
2095 escape sequences, including \NNN octal escapes. These escape sequences
2096 may be used in key sequence definitions or macro values.
2097
2098h. An `$include' inputrc file parser directive has been added.
2099
2100-------------------------------------------------------------------------------
2101This is a terse description of the new features added to bash-2.01 since
2102the release of bash-2.0. As always, the manual page (doc/bash.1) is the
2103place to look for complete descriptions.
2104
21051. New Features in Bash
2106
2107a. There is a new builtin array variable: GROUPS, the set of groups to which
2108 the user belongs. This is used by the test suite.
2109
21102. New Features in Readline
2111
2112a. If a key sequence bound to `universal-argument' is read while reading a
2113 numeric argument started with `universal-argument', it terminates the
2114 argument but is otherwise ignored. This provides a way to insert multiple
2115 instances of a digit string, and is how GNU emacs does it.
2116
2117-------------------------------------------------------------------------------
2118This is a terse description of the new features added to bash-2.0 since
2119the release of bash-1.14.7. As always, the manual page (doc/bash.1) is
2120the place to look for complete descriptions.
2121
21221. New Features in Bash
2123
2124a. There is a new invocation option, -D, that dumps translatable strings
2125 in a script.
2126
2127b. The `long' invocation options must now be prefixed with `--'.
2128
2129c. New long invocation options: --dump-strings, --help, --verbose
2130
2131d. The `nolineediting' invocation option was renamed to `noediting'.
2132
2133e. The `nobraceexpansion' and `quiet' long invocation options were removed.
2134
2135f. The `--help' and `--version' long options now work as the GNU coding
2136 standards specify.
2137
2138g. If invoked as `sh', bash now enters posix mode after reading the
2139 startup files, and reads and executes commands from the file named
2140 by $ENV if interactive (as POSIX.2 specifies). A login shell invoked
2141 as `sh' reads $ENV after /etc/profile and ~/.profile.
2142
2143h. There is a new reserved word, `time', for timing pipelines, builtin
2144 commands, and shell functions. It uses the value of the TIMEFORMAT
2145 variable as a format string describing how to print the timing
2146 statistics.
2147
2148i. The $'...' quoting syntax expands ANSI-C escapes in ... and leaves the
2149 result single-quoted.
2150
2151j. The $"..." quoting syntax performs locale-specific translation of ...
2152 and leaves the result double-quoted.
2153
2154k. LINENO now works correctly in functions.
2155
2156l. New variables: DIRSTACK, PIPESTATUS, BASH_VERSINFO, HOSTNAME, SHELLOPTS,
2157 MACHTYPE. The first three are array variables.
2158
2159m. The BASH_VERSION and BASH_VERSINFO variables now include the shell's
2160 `release status' (alpha[N], beta[N], release).
2161
2162n. Some variables have been removed: MAIL_WARNING, notify, history_control,
2163 command_oriented_history, glob_dot_filenames, allow_null_glob_expansion,
2164 nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and
2165 cdable_vars. Most of them are now implemented with the new `shopt'
2166 builtin; others were already implemented by `set'.
2167
2168o. Bash now uses some new variables: LC_ALL, LC_MESSAGES, LC_CTYPE,
2169 LC_COLLATE, LANG, GLOBIGNORE, HISTIGNORE.
2170
2171p. The shell now supports integer-indexed arrays of unlimited length,
2172 with a new compound assignment syntax and changes to the appropriate
2173 builtin commands (declare/typeset, read, readonly, etc.). The array
2174 index may be an arithmetic expression.
2175
2176q. ${!var}: indirect variable expansion, equivalent to eval \${$var}.
2177
2178r. ${parameter:offset[:length]}: variable substring extraction.
2179
2180s. ${parameter/pattern[/[/]string]}: variable pattern substitution.
2181
2182t. The $[...] arithmetic expansion syntax is no longer supported, in
2183 favor of $((...)).
2184
2185u. Aliases can now be expanded in shell scripts with a shell option
2186 (shopt expand_aliases).
2187
2188v. History and history expansion can now be used in scripts with
2189 set -o history and set -H.
2190
2191w. All builtins now return an exit status of 2 for incorrect usage.
2192
2193x. Interactive shells resend SIGHUP to all running or stopped children
2194 if (and only if) they exit due to a SIGHUP.
2195
2196y. New prompting expansions: \a, \e, \H, \T, \@, \v, \V.
2197
2198z. Variable expansion in prompt strings is now controllable via a shell
2199 option (shopt promptvars).
2200
2201aa. Bash now defaults to using command-oriented history.
2202
2203bb. The history file ($HISTFILE) is now truncated to $HISTFILESIZE after
2204 being written.
2205
2206cc. The POSIX.2 conditional arithmetic evaluation syntax (expr ? expr : expr)
2207 has been implemented.
2208
2209dd. Each builtin now accepts `--' to signify the end of the options, except
2210 as documented (echo, etc.).
2211
2212ee. All builtins use -p to display values in a re-readable format where
2213 appropriate, except as documented (echo, type, etc.).
2214
2215ff. The `alias' builtin has a new -p option.
2216
2217gg. Changes to the `bind' builtin:
2218 o has new options: -psPSVr.
2219 o the `-d' option was renamed to `-p'
2220 o the `-v' option now dumps variables; the old `-v' is now `-P'
2221
2222hh. The `bye' synonym for `exit' was removed.
2223
2224ii. The -L and -P options to `cd' and `pwd' have been documented.
2225
2226jj. The `cd' builtin now does spelling correction on the directory name
2227 by default. This is settable with a shell option (shopt cdspell).
2228
2229kk. The `declare' builtin has new options: -a, -F, -p.
2230
2231ll. The `dirs' builtin has new options: -c, -p, -v.
2232
2233mm. The new `disown' builtin removes jobs from the shell's jobs table
2234 or inhibits the resending of SIGHUP when the shell receives a
2235 SIGHUP.
2236
2237nn. The `echo' builtin has a new escape character: \e.
2238
2239oo. The `enable' builtin can now load new builtins dynamically from shared
2240 objects on systems with the dlopen/dlsym interface. There are a number
2241 of examples in the examples/loadables directory. There are also
2242 new options: -d, -f, -s, -p.
2243
2244pp. The `-all' option to `enable' was removed in favor of `-a'.
2245
2246qq. The `exec' builtin has new options: -l, -c, -a.
2247
2248rr. The `hash' builtin has a new option: -p.
2249
2250ss. The `history' builtin has new options: -c, -p, -s.
2251
2252tt. The `jobs' builtin has new options: -r, -s.
2253
2254uu. The `kill' builtin has new options: -n signum, -l signame.
2255
2256vv. The `pushd' and `popd' builtins have a new option: -n.
2257
2258ww. The `read' builtin has new options: -p prompt, -e, -a.
2259
2260xx. The `readonly' builtin has a new -a option, and the -n option was removed.
2261
2262yy. Changes to the `set' builtin:
2263 o new options: -B, -o keyword, -o onecmd, -o history
2264 o options removed: -l, -d, -o nohash
2265 o options changed: +o, -h, -o hashall
2266 o now displays variables in a format that can be re-read as input
2267
2268zz. The new `shopt' builtin controls shell optional behavior previously
2269 done by setting and unsetting certain shell variables.
2270
2271aaa. The `test' builtin has new operators: -o option, s1 == s2, s1 < s2,
2272 and s1 > s2, where s1 and s2 are strings.
2273
2274bbb. There is a new trap, DEBUG, executed after every simple command.
2275
2276ccc. The `trap' builtin has a new -p option.
2277
2278ddd. The `ulimit' builtin has a new -l option on 4.4BSD-based systems.
2279
2280eee. The PS1, PS2, PATH, and IFS variables may now be unset.
2281
2282fff. The restricted shell mode has been expanded and is now documented.
2283
2284ggg. Security improvements:
2285 o functions are not imported from the environment if running setuid
2286 or with -p
2287 o no startup files are sourced if running setuid or with -p
2288
2289hhh. The documentation has been overhauled: the texinfo manual was
2290 expanded, and HTML versions of the man page and texinfo manual
2291 are included.
2292
2293iii. Changes to Posix mode:
2294 o Command lookup now finds special builtins before shell functions.
2295 o Failure of a special builtin causes a non-interactive shell to
2296 exit. Failures are defined in the POSIX.2 specification.
2297 o If the `cd' builtin finds a directory to change to using $CDPATH,
2298 the value assigned to PWD when `cd' completes does not contain
2299 any symbolic links.
2300 o A non-interactive shell exits if a variable assignment error
2301 occurs when no command name follows the assignment statements.
2302 o A non-interactive shell exits if the iteration variable in a
2303 `for' statement or the selection variable in a `select' statement
2304 is read-only or another variable assignment error occurs.
2305 o The `<>' redirection operator now opens a file for both stdin and
2306 stdout by default, not just when in posix mode.
2307 o Assignment statements preceding special builtins now persist in
2308 the shell's environment when the builtin completes.
2309
2310 Posix mode is now completely POSIX.2-compliant (modulo bugs). When
2311 invoked as sh, bash should be completely POSIX.2-compliant.
2312
2313jjj. The default value of PS1 is now "\s-\v\$ ".
2314
2315kkk. The ksh-like ((...)) arithmetic command syntax has been implemented.
2316 This is exactly equivalent to `let "..."'.
2317
2318lll. Integer constants have been extended to base 64.
2319
2320mmm. The `ulimit' builtin now sets both hard and soft limits and reports the
2321 soft limit by default.
2322
23232. New Features in Readline
2324
2325a. New variables: enable-keypad, input-meta (new name for meta-flag),
2326 mark-directories, visible-stats (now documented), disable-completion,
2327 comment-begin.
2328
2329b. New bindable commands: kill-region, copy-region-as-kill,
2330 copy-backward-word, copy-forward-word, set-mark, exchange-point-and-mark,
2331 character-search, character-search-backward, insert-comment,
2332 glob-expand-word, glob-list-expansions, dump-variables, dump-macros.
2333
2334c. New emacs keybindings: delete-horizontal-space (M-\),
2335 insert-completions (M-*), possible-completions (M-=).
2336
2337d. The history-search-backward and history-search-forward commands were
2338 modified to be the same as previous-line and next-line if point is at
2339 the start of the line.
2340
2341e. More file types are available for the visible-stats mode.
2342
23433. Changes of interest in the Bash implementation
2344
2345a. There is a new autoconf-based configuration mechanism.
2346
2347b. More things have been moved from Posix mode to standard shell behavior.
2348
2349c. The trace output (set -x) now inserts quotes where necessary so it can
2350 be reused as input.
2351
2352d. There is a compile-time option for a system-wide interactive shell
2353 startup file (disabled by default).
2354
2355e. The YACC grammar is smaller and tighter, and all 66 shift-reduce
2356 conflicts are gone. Several parsing bugs have been fixed.
2357
2358f. Builtin option parsing has been regularized (using internal_getopt()),
2359 with the exception of `echo', `type', and `set'.
2360
2361g. Builtins now return standard usage messages constructed from the
2362 `short doc' used by the help builtin.
2363
2364h. Completion now quotes using backslashes by default, but honors
2365 user-supplied quotes.
2366
2367i. The GNU libc malloc is available as a configure-time option.
2368
2369j. There are more internationalization features; bash uses gettext if
2370 it is available. The $"..." translation syntax uses the current
2371 locale and gettext.
2372
2373k. There is better reporting of job termination when the shell is not
2374 interactive.
2375
2376l. The shell is somewhat more efficient: it uses a little less memory and
2377 makes fewer system calls.
2378
23794. Changes of interest in the Readline implementation
2380
2381a. There is now support for readline `callback' functions.
2382
2383b. There is now support for user-supplied input, redisplay, and terminal
2384 preparation functions.
2385
2386c. Most of the shell-specific code in readline has been generalized or
2387 removed.
2388
2389d. Most of the annoying redisplay bugs have been fixed, notably the problems
2390 with incremental search and excessive redrawing when special characters
2391 appear in the prompt string.
2392
2393e. There are new library functions and variables available to application
2394 writers, most having to do with completion and quoting.
2395
2396f. The NEWLINE character (^J) is now treated as a search terminator by the
2397 incremental search functions.
2398-------------------------------------------------------------------------------
2399
2400Copying and distribution of this file, with or without modification,
2401are permitted in any medium without royalty provided the copyright
2402notice and this notice are preserved. This file is offered as-is,
2403without any warranty.
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