1 This document details the changes between this version, bash-5.0-release, and
2 the previous version, bash-5.0-rc1.
6 a. Tilde expansion isn't performed on indexed array subscripts, even for
7 backwards compatibility.
9 b. The shell doesn't exit in posix mode if the eval builtin gets a parse
10 error when run by the command builtin.
12 c. Fixed a bug that caused a shell comment in an alias to not find the end
13 of the alias properly.
15 d. Reverted a change from April, 2018 that caused strings containing
16 backslashes to be flagged as glob patterns.
18 2. Changes to Readline
20 3. New Features in Bash
22 4. New Features in Readline
24 ------------------------------------------------------------------------------
25 This document details the changes between this version, bash-5.0-rc1, and
26 the previous version, bash-5.0-beta2.
30 a. Fix to initial word completion detection code.
32 b. Fixed a bug that caused issues with assignment statements containing ^A in
33 the value assigned when IFS contains ^A.
35 c. Added a fallback to fnmatch() when strcoll can't correctly deal with
36 bracket expression character equivalence classes.
38 d. Fixed a bug that caused $BASH_COMMAND to contain the trap handler command
39 when running a trap handler containing [[ or (( commands.
41 e. Fixed a bug that caused nameref assignments in the temporary environment
42 to potentially create variables with invalid names.
44 f. Fixed a bug that caused `local -' to turn off alias expansion in scripts.
46 g. Fixed a parser issue with a command string containing EOF after an invalid
47 command as an argument to a special builtin not causing a posix-mode shell
50 h. Made a slight change to the FNV-1 string hash algorithm used for associative
51 arrays (corrected the initial seed).
53 2. Changes to Readline
55 3. New Features in Bash
57 a. The `select' command now supports command forms without a word list
60 4. New Features in Readline
62 ------------------------------------------------------------------------------
63 This document details the changes between this version, bash-5.0-beta2, and
64 the previous version, bash-5.0-beta.
68 a. Fixed a bug that could cause a seg fault while parsing a subshell command
69 inside a command substitution.
71 b. Fixed several small memory leaks uncovered by coverity.
73 c. Fixed a problem with command substitution inside an interactive shell that
74 could cause the parent to receive a SIGHUP.
76 d. Fixed a problem with using `*' and `@' as subscripts when assigning values
77 to an associative array with assoc_expand_once enabled.
79 e. Fixed a bug that could cause a huge memory allocation when completing a
80 word beginning with an invalid tilde expansion.
82 f. Cleaned up some incompatiblities with bash-4.4 when expanding indexed array
83 subscripts used in arithmetic expansions when assoc_expand_once is enabled.
85 g. The ${parameter@a} expansion will display attributes even if `parameter' is
88 h. Fixed a bug that caused the output of `set' to cut off some variables before
91 i. Treat a failure to assign a variable when using the ${x:=value} expansion
92 as an expansion error, so non-interactive posix-mode shells exit
94 j. Fixed a problem when expanding $* in a context where word splitting is not
95 performed when IFS is NULL.
97 k. Temp files used to store here documents are forced readable, no matter what
98 the user's umask says.
100 l. Fixed a problem where an interrupted brace expansion could cause the shell
101 to attempt to free an invalid memory location.
103 m. Make sure to check for any terminating signals after running a trap
104 handler; don't wait until the next time we process traps.
106 n. Fixed a bug that caused "return" to act like a special builtin with respect
107 to variable assignments even when preceded by "command".
109 o. POSIX-mode shells now return failure if the cd builtin fails due to the
110 absolute directory name being longer than PATH_MAX, instead of trying
111 again with a relative pathname.
113 p. Fixed a problem with FUNCNAME occasionally being visible when not executing
116 q. Fixed a problem with the expansions performed on the WORD in the case
119 r. Fixed a slight POSIX compatibility when removing "IFS whitespace" during
120 word splitting and the read builtin.
122 s. Fixed a problem with expanding an array with subscript `*' when all the
123 elements expand to the empty string, and making sure the expansion honors
126 2. Changes to Readline
128 a. Fixed a bug with adding multibyte characters to an incremental search string.
130 b. Fixed a bug with redoing text insertions in vi mode.
132 c. Fixed a bug with pasting text into an incremental search string if bracketed
133 paste mode is enabled. ESC cannot be one of the incremental search
134 terminator characters for this to work.
136 d. Fixed a bug with anchored search patterns when performing searches in vi
139 3. New Features in Bash
141 a. Associative and indexed arrays now allow subscripts consisting solely of
144 b. `checkwinsize' is now enabled by default.
146 c. The `localvar_unset' shopt option is now visible and documented.
148 d. The `progcomp_alias' shopt option is now visible and documented.
150 e. The signal name processing code now understands `SIGRTMIN+n' all the way
153 f. There is a new `seq' loadable builtin.
155 g. Trap execution now honors the (internal) max invocations of `eval', since
156 traps are supposed to be executed as if using `eval'.
158 h. The $_ variable doesn't change when the shell executes a command that forks.
160 i. The `kill' builtin now supports -sSIGNAME and -nSIGNUM, even though
161 conforming applications aren't supposed to use them.
163 j. POSIX mode now enables the `shift_verbose' option.
165 4. New Features in Readline
167 a. Readline now allows application-defined keymap names; there is a new public
168 function, rl_set_keymap_name(), to do that.
170 b. The "Insert" keypad key, if available, now puts readline into overwrite
173 ------------------------------------------------------------------------------
174 This document details the changes between this version, bash-5.0-beta, and
175 the previous version, bash-5.0-alpha.
179 a. Fixed a bug that allowed subshells to "inherit" enclosing loops -- this
180 is where POSIX says the subshell is not "enclosed" by the loop.
182 b. Added more UTF-8-specific versions of multibyte functions, and optimized
183 existing functions if the current locale uses UTF-8 encoding.
185 c. In POSIX mode, assignments preceding regular builtins should not persist
186 when the builtin completes.
188 d. Added additional checks to special array assignment (e.g., BASH_ALIASES)
189 so it can't be used to bypass validity checks performed in other places.
191 e. The `!!' history expansion now refers to the previous history entry as
192 expected, even if used on the second or subsequent line of a multi-line
195 f. Fixed a bug that could cause the shell to dereference a NULL pointer if
196 the environment (`environ') is set to NULL.
198 g. Bash uses slightly better integer overflow handling for brace sequence
199 expansion on systems where ints are 32 bits and intmax_t is 64 bits.
201 h. Fixed a bug setting attributes for a variable named as an argument to
202 `declare' that also appears as a nameref in the temporary environment.
204 i. Fixed several bugs that could cause assignments to namerefs to create
205 variables with invalid names.
207 j. Fixed a bug that could result in the SIGINT handler being set incorrectly
208 in asynchronous subshells.
210 k. Fixed a bug that could cause `bash -t' to not execute the specified command.
212 l. Fixed several bugs that caused the shell to operate on the wrong variable
213 when using namerefs with the same name as a global variable in shell
216 m. Internal changes to how the shell handles variables with invalid names in
217 the initial environment and to prevent variables with invalid names from
218 being added to the environment instead of passing them on to children.
220 n. Changes to make sure that an expansion that results in a quoted null string
221 is reflected in the expansion, even if the word expands to nothing.
223 o. Changes to make sure that $* and ${array[*]} (and $@/${array[@]}) expand
224 the same way after the recent changes for POSIX interpretation 888.
226 p. Saving and restoring the positional parameters at function entry and exit
227 is considerably more efficient; noticeably so when there are large numbers
228 of positional parameters.
230 q. Fixed a bug that caused `lastpipe' and `pipefail' to return an incorrect
231 status for the pipeline if there was more than one external command in a
232 loop body appearing in the last pipeline element.
234 r. Fixed a bug that caused value conversion errors with the printf builtin's
235 %u and %f conversion specifications and invalid constants.
237 2. Changes to Readline
239 a. Added more UTF-8-specific versions of multibyte functions, and optimized
240 existing functions if the current locale uses UTF-8 encoding.
242 b. Fixed a problem with bracketed-paste inserting more than one character and
243 interacting with other readline functions.
245 c. Fixed a bug that caused the history library to attempt to append a history
246 line to a non-existent history entry.
248 d. If using bracketed paste mode, output a newline after the \r that is the
249 last character of the mode disable string to avoid overwriting output.
251 e. Fixes to the vi-mode `b', `B', `w', `W', `e', and `E' commands to better
252 handle multibyte characters.
254 f. Fixed a redisplay problem that caused an extra newline to be generated on
255 accept-line when the line length is exactly the screenwidth.
257 3. New Features in Bash
259 a. Bash no longer allows variable assignments preceding a special builtin that
260 changes variable attributes to propagate back to the calling environment
261 unless the compatibility level is 44 or lower.
263 b. You can set the default value for $HISTSIZE at build time in config-top.h.
265 c. The `complete' builtin now accepts a -I option that applies the completion
266 to the initial word on the line.
268 d. The internal bash malloc now uses mmap (if available) to satisfy requests
269 greater than 128K bytes, so free can use mfree to return the pages to the
272 e. The shell doesn't automatically set BASH_ARGC and BASH_ARGV at startup
273 unless it's in debugging mode, as the documentation has always said, but
274 will dynamically create them if a script references them at the top level
275 without having enabled debugging mode.
277 f. The localvar_inherit option will not attempt to inherit a value from a
278 variable of an incompatible type (indexed vs. associative arrays, for
281 g. The `globasciiranges' option is now enabled by default; it can be set to
282 off by default at configuration time.
284 4. New Features in Readline
286 a. The history expansion library now understands command and process
287 substitution and extended globbing and allows them to appear anywhere in a
290 b. The history library has a new variable that allows applications to set the
291 initial quoting state, so quoting state can be inherited from a previous
294 ------------------------------------------------------------------------------
295 This document details the changes between this version, bash-5.0-alpha, and
296 the previous version, bash-4.4-release.
300 a. Fixed a bug that could cause traps in background jobs to give the terminal
301 to the wrong process group.
303 b. Fixed a bug that caused `kill -l 0' to print an out-of-range error.
305 c. Fixed a problem that could result in here-documents being displayed in
308 d. Fixed a number of out-of-bounds and free memory read errors found via
311 e. Fixed a subshell inheritance problem that could cause a subshell to wait for
314 f. Fixed a bug that caused SHLVL to be incremented one too many times when
317 g. A job dying due to SIGINT can now interrupt sourcing a file in a shell with
320 h. Fixed a spurious warning about unterminated ${ or $( constructs during
323 i. The shell no longer runs traps if a signal arrives while reading command
326 j. Fixed an arithmetic expansion error that could allow ++var++ as valid
329 k. Fixed an error that allowed out-of-bounds references to the directory stack.
331 l. The shell does a better job of saving multi-line history entries with
334 m. Fixed a bug that could cause quoted bracket expressions in regular expression
335 arguments to `[[' to not match correctly.
337 n. Fixed a bug that could cause an IFS character in a word to result in an
338 extra '\001' character in the expansion.
340 o. A trailing backslash in a glob pattern can match a trailing backslash in the
343 p. Fixed a memory leak in the process creation code path when job control is
346 q. Fixed a bug that caused `printf' to output broken surrogate pairs for
349 r. Fixed a bug that caused a SIGINT generated from `kill' in a dot script to
350 kill an interactive shell.
352 s. Fixed a bug that could cause the `read' builtin to not fully read a
355 t. Fixed a bug that could cause identifiers to be evaluated in conditional
356 arithmetic expressions even when evaluation is suppressed.
358 u. Fixed a bug that could result in command substitution, when executed in a
359 context where word splitting is not performed, to leave a stray '\001'
360 character in the string.
362 v. Fixed a bug that could cause history expansion to be disabled in a non-
363 interactive shell even if `-o histexpand' is supplied at startup.
365 w. Fixed a bug that caused `read -N' to strip leading whitespace IFS characters.
367 x. Fixed a bug that caused spurious tilde expansion in arithmetic expressions.
369 y. If indirect expansion attempts to indirectly reference through an unset
370 variable, report an error.
372 z. Added a guard to prevent the shell from looping while receiving an endless
373 stream of SIGTTIN at shell startup.
375 aa. Fixed a bug with parsing here documents inside a command substitution when
376 looking for the closing delimiter.
378 bb. Fixed a bug that caused printf to not quote all <blank> characters in the
379 current locale when using the `%q' format specifier.
381 cc. Fixed a bug with bash's internal buffered I/O system that caused the input
382 pointer to not be reset when read(2) returned an EOF.
384 dd. Bash now installs its SIGWINCH signal handler with SA_RESTART, so it will
385 not interrupt open/read/write system calls.
387 ee. The ERR trap now reports line numbers more reliably.
389 ff. The shell no longer tries to manipulate the terminal process group if a
390 command or process substitution is killed by SIGTERM when job control is
393 gg. Fixed a bug that caused extglob patterns to match filenames beginning with
396 hh. File descriptors open for writing to here documents are no longer available
399 ii. Make sure word completion doesn't perform command or process substitution.
401 jj. Fixed a bug with parsing $$'...' inside a command substitution.
403 kk. Fixed a bug that caused bash to remove backslash-newline pairs from the
404 body of a here-document with a quoted delimiter inside a command
407 ll. Fixed a bug that could cause the shell to hang when adding a pid to the
408 table of background process exit statuses.
410 mm. Fixed a bug that could cause 0x01 characters to be doubled in the output
411 of process substitution.
413 nn. Restricted shells now clear the hash table before making the PATH variable
416 oo. There are a number of changes to the expansion of $* and $@ in contexts
417 where word splitting does not occur (quoted and unquoted), with IFS set
418 to NULL or a non-standard value, mostly to deal with the consequences of
419 the behavior defined in Posix interpretation 888.
421 pp. There are a number of changes to nameref variable handling to avoid
422 creating variables with invalid names.
424 qq. A non-interactive posix mode shell no longer exits when an assignment
425 statement fails if the assignment is utimately being performed by the
428 rr. When using character class names for globbing, don't allow case
429 insensitivity, even if nocaseglob is enabled.
431 ss. Fixed a bug that allowed some redirections to stay in place if a later
434 tt. Fixed a bug in how command and process substitutions are recognized within
435 other parameter expansions.
437 uu. Fixed a bug that caused bash to loop under certain circumstances when
438 performing arithmetic expansion on a variable whose value is an invalid
441 vv. Fixed a bug that could cause bash to expand aliases inappropriately while
442 parsing compound commands like `case'.
444 ww. Fixed a bug that could cause `read -N' to fail to read complete multibyte
445 characters, even when the sequences are incomplete or invalid, with or
448 xx. Fixed a bug that could cause `case' to fail to match patterns containing
451 yy. Fixed a bug that caused exported functions to contain stray 0x01 characters.
453 zz. Fixed some inconsistencies with how the history number is handled in the
454 various prompt strings.
456 aaa. Fixed a bug that could cause a core dump if READLINE_LINE was unset
457 inside a shell function bound to a key sequence with `bind -x'.
459 bbb. Fixed a bug that could cause bash to not read a token terminator correctly
460 if a command substitution was used inside an arithmetic `for' command.
462 ccc. Fixed problems that could occur with a fatal arithmetic expansion error
463 in a context (like prompt expansion) where you can't jump back to the
466 ddd. Expression errors in arithmetic `for' commands are treated more like
469 eee. Fixed a parser synchronization error resulting from a syntax error
470 followed immediately by an EOF.
472 fff. When executing a shell function, the first line in the function ($LINENO)
473 is line 1 instead of line 0, as Posix requires.
475 ggg. In Posix mode, bash will canonicalize the value of PWD it inherits from
476 the environment and use that to set its idea of the current directory.
478 hhh. If LINENO is exported, bash needs to regenerate its value each time it
479 constructs the environment.
481 iii. Fixed a bug with restoring the SIGINT handler when using `wait -n'.
483 jjj. Make sure the `coproc' command returns an appropriate status if the NAME
486 kkk. Fixed a problem with arithmetic expressions containing array references
487 that contain arithmetic expressions with syntax errors.
489 lll. The `select' command and help builtin will use $COLUMNS before the window
490 size returned from the kernel as the terminal width.
492 mmm. `read -n 0' and `read -N 0' now try a zero-length read in an attempt to
493 detect file descriptor errors.
495 nnn. The `read' builtin now does a better job of acting on signals that don't
498 ooo. Fixed some cases where `printf -v' did not return failure status on a
499 variable assignment error.
501 ppp. Fixed temporary environment propagation back to the current environment
502 so that it doesn't happen for special builtins run by the `command'
505 qqq. Fixed a bug when searching for the end of a here-document delimiter in a
506 command substitution.
508 rrr. Fixed a bug that could cause `cd ${DIRSTACK[0]}' to fail.
510 sss. Fixed a bug that could cause reserved words to not be recognized in a
511 for statement without the `in' inside a command substitution.
513 ttt. Fixed a bug that could cause a double-free in a timed command with an
516 uuu. Fixed a bug that could cause a core dump if a script switches from a UTF-8
517 locale to a different locale after displaying a lone surrogate character.
519 vvv. Fixed cases where bash prematurely removed FIFOs attached to process
522 www. Fixed a problem with calculating the size of the table that stores exit
523 statuses from background processes when the child process resource limit
526 xxx. Fixed a memory leak with functions using `return' when using FIFOs for
529 yyy. `wait' without arguments attempts to wait for all active process
530 substitution processes.
532 zzz. Fixed a bug where an indirect parameter was subjected to word splitting
533 when trying to find the indirected variable name.
535 aaaa. Fixed a bug that could allow restricted shell users to add commands to
538 bbbb. When using the `!(patlist)' extended globbing operator, a filename
539 beginning with a `.' that doesn't match any of the patterns is not
540 returned as a match if leading dots must be matched explicitly.
542 cccc. Fixed a bug that could cause line number and source file information for
543 a function definition to be incorrect if there are multiple definitions.
545 dddd. Fixed a bug that could cause builtins like `readonly' to behave
546 differently when applied to arrays and scalar variables within functions.
548 eeee. Fixed a bug that could cause alias expansion to add an extra space to
549 a quoted string that begins outside the alias expansion.
551 ffff. Fixed a bug that could result in unwanted alias expansion after timing
554 gggg. Fixed a bug that could cause a core dump if a timestamp in a history
555 file overflowed a time_t.
557 hhhh. Restricted shells can no longer redirect from /dev/tcp or /dev/udp, since
558 the kernel calls make those file descriptors read-write.
560 iiii. Fixed a problem with splitting double-quoted words for programmable
561 completion when the double quote immediately follows another word
564 jjjj. Fixed a bug resulting in a use-after-free if two file descriptors share
565 the same input buffer.
567 kkkk. The error message resulting from ${x:?} and ${x?} now differs depending
568 on whether the variable is null or unset.
570 llll. In Posix mode, the shell exits if a variable assignment fails and precedes
571 an empty simple command (after expansion).
573 mmmm. Fixed a timing problem with SIGALRM that could cause the read builtin to
576 nnnn. Added code to deal with kill(2) failing to send the shell a fatal signal
577 due to Linux pid namespace peculiarities.
579 oooo. Fixed a bug that made \C-@ (NUL) unusable in key sequences used for
582 pppp. Fixed a bug that could cause SIGINT recursion when running an external
583 command in a trap the shell takes after a command exits due to SIGINT.
585 qqqq. Make sure the shell turns off job control before running the command-
586 not-found handle, so the command doesn't try to manipulate process
589 rrrr. Fixed a problem with timing process substitutions that caused the shell
590 to print timing information for the calling command.
592 ssss. Fixed a bug that caused backquotes in a here-document delimiter to mark
593 the delimiter as quoted (inhibiting expansion of the here-document
596 tttt. Fixed several problems with 0x01 and 0x177 in case pattern lists and
597 conditional command pattern matches.
599 uuuu. Fixed a bug that could cause the pattern matching engine to not recognize
600 locale-specific character classes.
602 vvvv. The auto-configuration now tests for /dev/stdin and /dev/fd independently.
604 wwww. The `globstar' code now skips over symbolic links to directories,
605 preventing them from being scanned twice.
607 xxxx. When running `bind -x' commands, bash now sets READLINE_POINT based on
608 the number of characters in the readline line buffer, not the number of
611 yyyy. Fixed a problem that could cause recursive trap evaluation of the RETURN
612 trap when using `eval return'.
614 zzzz. Fixed a bug with expanding 0x01 in an unquoted here-document.
616 aaaaa. The process substitution code now closes and unlinks FIFOs when the
617 process on the other side exits, in order to prevent SIGPIPE or
618 waiting until a FIFO opened for read has a writer.
620 bbbbb. Fixed a bug with recursive calls to the parser overwriting the token in
621 an {id}>foo construct.
623 ccccc. After a Posix discussion, the pattern matching engine just skips over
624 invalid character classes in bracket expressions, instead of matching
625 them like individual characters in the expression.
627 ddddd. Fixed a posix-mode problem with variable scoping when creating variables
628 from assignment statements preceding special builtins.
630 eeeee. Fixed a bug that could cause patterns containing backslashes to not be
631 run through the pattern matching engine.
633 fffff. Fixed a bug that could cause redirections to compound commands to not
634 be `undone' if the file descriptor in the redirection was closed when
635 the redirection was initially processed.
637 ggggg. Fixed a bug that could cause buffer corruption when using `bind -x' in
638 a command execute as a result of a key binding installed by `bind -x'.
640 2. Changes to Readline
642 a. Added a guard to prevent nested macros from causing an infinite expansion
645 b. Instead of allocating enough history list entries to hold the maximum list
646 size, cap the number allocated initially.
648 c. Added a strategy to avoid allocating huge amounts of memory if a block of
649 history entries without timestamps occurs after a block with timestamps.
651 d. Added support for keyboard timeouts when an ESC character is the last
652 character in a macro.
654 e. There are several performance improvements when in a UTF-8 locale.
656 f. Readline does a better job of preserving the original set of blocked
657 signals when using pselect() to wait for input.
659 g. Fixed a bug that caused multibyte characters in macros to be mishandled.
661 h. Fixed several bugs in the code that calculates line breaks when expanding
662 prompts that span several lines, contain multibyte characters, and contain
663 invisible character seqeuences.
665 i. Fixed several bugs in cursor positioning when displaying lines with prompts
666 containing invisible characters and multibyte characters.
668 j. When performing case-insensitive completion, Readline no longer sorts the
669 list of matches unless directed to do so.
671 k. Fixed a problem with key sequences ending with a backslash.
673 l. Fixed out-of-bounds and free memory read errors found via fuzzing.
675 m. Fixed several cases where the mark was set to an invalid value.
677 n. Fixed a problem with the case-changing operators in the case where the
678 lower and upper case versions of a character do not have the same number
681 o. Handle incremental and non-incremental search character reads returning EOF.
683 p. Handle the case where a failing readline command at the end of a multi-key
684 sequence could be misinterpreted.
686 q. The history library now prints a meaningful error message if the history
687 file isn't a regular file.
689 r. Fixed a problem with vi-mode redo (`.') on a command when trying to replace
690 a multibyte character.
692 s. The key binding code now attempts to remove a keymap if a key unbinding
695 t. Fixed a line-wrapping issue that caused problems for some terminal
698 u. If there is a key bound to the tty's VDISCARD special character, readline
699 disables VDISCARD while it is active.
701 v. Fixed a problem with exiting bracketed paste mode on terminals that assume
702 the bracketed paste mode character sequence contains visible characters.
704 w. Fixed a bug that could cause a key binding command to refer to an
705 uninitialized variable.
707 3. New Features in Bash
709 a. The `wait' builtin can now wait for the last process substitution created.
711 b. There is an EPOCHSECONDS variable, which expands to the time in seconds
712 since the Unix epoch.
714 c. There is an EPOCHREALTIME variable, which expands to the time in seconds
715 since the Unix epoch with microsecond granularity.
717 d. New loadable builtins: rm, stat, fdflags.
719 e. BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment.
721 f. When supplied a numeric argument, the shell-expand-line bindable readline
722 command does not perform quote removal and suppresses command and process
725 g. `history -d' understands negative arguments: negative arguments offset from
726 the end of the history list.
728 h. The `name' argument to the `coproc' reserved word now undergoes word
729 expansion, so unique coprocs can be created in loops.
731 i. A nameref name resolution loop in a function now resolves to a variable by
732 that name in the global scope.
734 j. The `wait' builtin now has a `-f' option, which signfies to wait until the
735 specified job or process terminates, instead of waiting until it changes
738 k. There is a define in config-top.h that allows the shell to use a static
739 value for $PATH, overriding whatever is in the environment at startup, for
740 use by the restricted shell.
742 l. Process substitution does not inherit the `v' option, like command
745 m. If a non-interactive shell with job control enabled detects that a foreground
746 job died due to SIGINT, it acts as if it received the SIGINT.
748 n. The SIGCHLD trap is run once for each exiting child process even if job
749 control is not enabled when the shell is in Posix mode.
751 o. A new shopt option: localvar_inherit; if set, a local variable inherits the
752 value of a variable with the same name at the nearest preceding scope.
754 p. `bind -r' now checks whether a key sequence is bound before binding it to
755 NULL, to avoid creating keymaps for a multi-key sequence.
757 q. A numeric argument to the line editing `operate-and-get-next' command
758 specifies which history entry to use.
760 r. The positional parameters are now assigned before running the shell startup
761 files, so startup files can use $@.
763 s. There is a compile-time option that forces the shell to disable the check
764 for an inherited OLDPWD being a directory.
766 t. The `history' builtin can now delete ranges of history entries using
769 u. The `vi-edit-and-execute-command' bindable readline command now puts readline
770 back in vi insertion mode after executing commands from the edited file.
772 v. The command completion code now matches aliases and shell function names
773 case-insensitively if the readline completion-ignore-case variable is set.
775 w. There is a new `assoc_expand_once' shell option that attempts to expand
776 associative array subscripts only once.
778 x. The shell only sets up BASH_ARGV and BASH_ARGC at startup if extended
779 debugging mode is active. The old behavior of unconditionally setting them
780 is available as part of the shell compatibility options.
782 y. The `umask' builtin now allows modes and masks greater than octal 777.
784 z. The `times' builtin now honors the current locale when printing a decimal
787 aa. There is a new (disabled by default, undocumented) shell option to enable
788 and disable sending history to syslog at runtime.
790 4. New Features in Readline
792 a. Non-incremental vi-mode search (`N', `n') can search for a shell pattern, as
793 Posix specifies (uses fnmatch(3) if available).
795 b. There are new `next-screen-line' and `previous-screen-line' bindable
796 commands, which move the cursor to the same column in the next, or previous,
797 physical line, respectively.
799 c. There are default key bindings for control-arrow-key key combinations.
801 d. A negative argument (-N) to `quoted-insert' means to insert the next N
802 characters using quoted-insert.
804 e. New public function: rl_check_signals(), which allows applications to
805 respond to signals that readline catches while waiting for input using
806 a custom read function.
808 f. There is new support for conditionally testing the readline version in an
809 inputrc file, with a full set of arithmetic comparison operators available.
811 g. There is a simple variable comparison facility available for use within an
812 inputrc file. Allowable operators are equality and inequality; string
813 variables may be compared to a value; boolean variables must be compared to
814 either `on' or `off'; variable names are separated from the operator by