Changelog:
This is a terse description of the new features added to bash-5.0 since
the release of bash-4.4. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The `wait' builtin can now wait for the last process substitution created.
b. There is an EPOCHSECONDS variable, which expands to the time in seconds
since the Unix epoch.
c. There is an EPOCHREALTIME variable, which expands to the time in seconds
since the Unix epoch with microsecond granularity.
d. New loadable builtins: rm, stat, fdflags.
e. BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment.
f. When supplied a numeric argument, the shell-expand-line bindable readline
command does not perform quote removal and suppresses command and process
substitution.
g. `history -d' understands negative arguments: negative arguments offset from
the end of the history list.
h. The `name' argument to the `coproc' reserved word now undergoes word
expansion, so unique coprocs can be created in loops.
i. A nameref name resolution loop in a function now resolves to a variable by
that name in the global scope.
j. The `wait' builtin now has a `-f' option, which signfies to wait until the
specified job or process terminates, instead of waiting until it changes
state.
k. There is a define in config-top.h that allows the shell to use a static
value for $PATH, overriding whatever is in the environment at startup, for
use by the restricted shell.
l. Process substitution does not inherit the `v' option, like command
substitution.
m. If a non-interactive shell with job control enabled detects that a foreground
job died due to SIGINT, it acts as if it received the SIGINT.
n. The SIGCHLD trap is run once for each exiting child process even if job
control is not enabled when the shell is in Posix mode.
o. A new shopt option: localvar_inherit; if set, a local variable inherits the
value of a variable with the same name at the nearest preceding scope.
p. `bind -r' now checks whether a key sequence is bound before binding it to
NULL, to avoid creating keymaps for a multi-key sequence.
q. A numeric argument to the line editing `operate-and-get-next' command
specifies which history entry to use.
r. The positional parameters are now assigned before running the shell startup
files, so startup files can use $@.
s. There is a compile-time option that forces the shell to disable the check
for an inherited OLDPWD being a directory.
t. The `history' builtin can now delete ranges of history entries using
`-d start-end'.
u. The `vi-edit-and-execute-command' bindable readline command now puts readline
back in vi insertion mode after executing commands from the edited file.
v. The command completion code now matches aliases and shell function names
case-insensitively if the readline completion-ignore-case variable is set.
w. There is a new `assoc_expand_once' shell option that attempts to expand
associative array subscripts only once.
x. The shell only sets up BASH_ARGV and BASH_ARGC at startup if extended
debugging mode is active. The old behavior of unconditionally setting them
is available as part of the shell compatibility options.
y. The `umask' builtin now allows modes and masks greater than octal 777.
z. The `times' builtin now honors the current locale when printing a decimal
point.
aa. There is a new (disabled by default, undocumented) shell option to enable
and disable sending history to syslog at runtime.
bb. Bash no longer allows variable assignments preceding a special builtin that
changes variable attributes to propagate back to the calling environment
unless the compatibility level is 44 or lower.
cc. You can set the default value for $HISTSIZE at build time in config-top.h.
dd. The `complete' builtin now accepts a -I option that applies the completion
to the initial word on the line.
ee. The internal bash malloc now uses mmap (if available) to satisfy requests
greater than 128K bytes, so free can use mfree to return the pages to the
kernel.
ff. The shell doesn't automatically set BASH_ARGC and BASH_ARGV at startup
unless it's in debugging mode, as the documentation has always said, but
will dynamically create them if a script references them at the top level
without having enabled debugging mode.
gg. The localvar_inherit option will not attempt to inherit a value from a
variable of an incompatible type (indexed vs. associative arrays, for
example).
hh. The `globasciiranges' option is now enabled by default; it can be set to
off by default at configuration time.
ii. Associative and indexed arrays now allow subscripts consisting solely of
whitespace.
jj. `checkwinsize' is now enabled by default.
kk. The `localvar_unset' shopt option is now visible and documented.
ll. The `progcomp_alias' shopt option is now visible and documented.
mm. The signal name processing code now understands `SIGRTMIN+n' all the way
up to SIGRTMAX.
nn. There is a new `seq' loadable builtin.
oo. Trap execution now honors the (internal) max invocations of `eval', since
traps are supposed to be executed as if using `eval'.
pp. The $_ variable doesn't change when the shell executes a command that forks.
qq. The `kill' builtin now supports -sSIGNAME and -nSIGNUM, even though
conforming applications aren't supposed to use them.
rr. POSIX mode now enables the `shift_verbose' option.
2. New Features in Readline
a. Non-incremental vi-mode search (`N', `n') can search for a shell pattern, as
Posix specifies (uses fnmatch(3) if available).
b. There are new `next-screen-line' and `previous-screen-line' bindable
commands, which move the cursor to the same column in the next, or previous,
physical line, respectively.
c. There are default key bindings for control-arrow-key key combinations.
d. A negative argument (-N) to `quoted-insert' means to insert the next N
characters using quoted-insert.
e. New public function: rl_check_signals(), which allows applications to
respond to signals that readline catches while waiting for input using
a custom read function.
f. There is new support for conditionally testing the readline version in an
inputrc file, with a full set of arithmetic comparison operators available.
g. There is a simple variable comparison facility available for use within an
inputrc file. Allowable operators are equality and inequality; string
variables may be compared to a value; boolean variables must be compared to
either `on' or `off'; variable names are separated from the operator by
whitespace.
h. The history expansion library now understands command and process
substitution and extended globbing and allows them to appear anywhere in a
word.
i. The history library has a new variable that allows applications to set the
initial quoting state, so quoting state can be inherited from a previous
line.
j. Readline now allows application-defined keymap names; there is a new public
function, rl_set_keymap_name(), to do that.
k. The "Insert" keypad key, if available, now puts readline into overwrite
mode.
This is a terse description of the new features added to bash-4.4 since
the release of bash-4.3. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. There is now a settable configuration #define that will cause the shell
to exit if the shell is running setuid without the -p option and setuid
to the real uid fails.
b. Command and process substitutions now turn off the `-v' option when
executing, as other shells seem to do.
c. The default value for the `checkhash' shell option may now be set at
compile time with a #define.
d. The `mapfile' builtin now has a -d option to use an arbitrary character
as the record delimiter, and a -t option to strip the delimiter as
supplied with -d.
e. The maximum number of nested recursive calls to `eval' is now settable in
config-top.h; the default is no limit.
f. The `-p' option to declare and similar builtins will display attributes for
named variables even when those variables have not been assigned values
(which are technically unset).
g. The maximum number of nested recursive calls to `source' is now settable
in config-top.h; the default is no limit.
h. All builtin commands recognize the `--help' option and print a usage
summary.
i. Bash does not allow function names containing `/' and `=' to be exported.
j. The `ulimit' builtin has new -k (kqueues) and -P (pseudoterminals) options.
k. The shell now allows `time ; othercommand' to time null commands.
l. There is a new `--enable-function-import' configuration option to allow
importing shell functions from the environment; import is enabled by
default.
m. `printf -v var ""' will now set `var' to the empty string, as if `var=""'
had been executed.
n. GLOBIGNORE, the pattern substitution word expansion, and programmable
completion match filtering now honor the value of the `nocasematch' option.
o. There is a new ${parameter@spec} family of operators to transform the
value of `parameter'.
p. Bash no longer attempts to perform compound assignment if a variable on the
rhs of an assignment statement argument to `declare' has the form of a
compound assignment (e.g., w='(word)' ; declare foo=$w); compound
assignments are accepted if the variable was already declared as an array,
but with a warning.
q. The declare builtin no longer displays array variables using the compound
assignment syntax with quotes; that will generate warnings when re-used as
input, and isn't necessary.
r. Executing the rhs of && and || will no longer cause the shell to fork if
it's not necessary.
s. The `local' builtin takes a new argument: `-', which will cause it to save
and the single-letter shell options and restore their previous values at
function return.
t. `complete' and `compgen' have a new `-o nosort' option, which forces
readline to not sort the completion matches.
u. Bash now allows waiting for the most recent process substitution, since it
appears as $!.
v. The `unset' builtin now unsets a scalar variable if it is subscripted with
a `0', analogous to the ${var[0]} expansion.
w. `set -i' is no longer valid, as in other shells.
x. BASH_SUBSHELL is now updated for process substitution and group commands
in pipelines, and is available with the same value when running any exit
trap.
y. Bash now checks $INSIDE_EMACS as well as $EMACS when deciding whether or
not bash is being run in a GNU Emacs shell window.
z. Bash now treats SIGINT received when running a non-builtin command in a
loop the way it has traditionally treated running a builtin command:
running any trap handler and breaking out of the loop.
aa. New variable: EXECIGNORE; a colon-separate list of patterns that will
cause matching filenames to be ignored when searching for commands.
bb. Aliases whose value ends in a shell metacharacter now expand in a way to
allow them to be `pasted' to the next token, which can potentially change
the meaning of a command (e.g., turning `&' into `&&').
cc. `make install' now installs the example loadable builtins and a set of
bash headers to use when developing new loadable builtins.
dd. `enable -f' now attempts to call functions named BUILTIN_builtin_load when
loading BUILTIN, and BUILTIN_builtin_unload when deleting it. This allows
loadable builtins to run initialization and cleanup code.
ee. There is a new BASH_LOADABLES_PATH variable containing a list of directories
where the `enable -f' command looks for shared objects containing loadable
builtins.
ff. The `complete_fullquote' option to `shopt' changes filename completion to
quote all shell metacharacters in filenames and directory names.
gg. The `kill' builtin now has a `-L' option, equivalent to `-l', for
compatibility with Linux standalone versions of kill.
hh. BASH_COMPAT and FUNCNEST can be inherited and set from the shell's initial
environment.
ii. inherit_errexit: a new `shopt' option that, when set, causes command
substitutions to inherit the -e option. By default, those subshells disable
-e. It's enabled as part of turning on posix mode.
jj. New prompt string: PS0. Expanded and displayed by interactive shells after
reading a complete command but before executing it.
kk. Interactive shells now behave as if SIGTSTP/SIGTTIN/SIGTTOU are set to
SIG_DFL when the shell is started, so they are set to SIG_DFL in child
processes.
ll. Posix-mode shells now allow double quotes to quote the history expansion
character.
mm. OLDPWD can be inherited from the environment if it names a directory.
nn. Shells running as root no longer inherit PS4 from the environment, closing
a security hole involving PS4 expansion performing command substitution.
oo. If executing an implicit `cd' when the `autocd' option is set, bash will
now invoke a function named `cd' if one exists before executing the `cd'
builtin.
pp. Value conversions (arithmetic expansions, case modification, etc.) now
happen when assigning elements of an array using compound assignment.
qq. There is a new option settable in config-top.h that makes multiple
directory arguments to `cd' a fatal error.
rr. Bash now uses mktemp() when creating internal temporary files; it produces
a warning at build time on many Linux systems.
2. New Features in Readline
a. The history truncation code now uses the same error recovery mechansim as
the history writing code, and restores the old version of the history file
on error. The error recovery mechanism handles symlinked history files.
b. There is a new bindable variable, `enable-bracketed-paste', which enables
support for a terminal's bracketed paste mode.
c. The editing mode indicators can now be strings and are user-settable
(new `emacs-mode-string', `vi-cmd-mode-string' and `vi-ins-mode-string'
variables). Mode strings can contain invisible character sequences.
Setting mode strings to null strings restores the defaults.
d. Prompt expansion adds the mode string to the last line of a multi-line
prompt (one with embedded newlines).
e. There is a new bindable variable, `colored-completion-prefix', which, if
set, causes the common prefix of a set of possible completions to be
displayed in color.
f. There is a new bindable command `vi-yank-pop', a vi-mode version of emacs-
mode yank-pop.
g. The redisplay code underwent several efficiency improvements for multibyte
locales.
h. The insert-char function attempts to batch-insert all pending typeahead
that maps to self-insert, as long as it is coming from the terminal.
i. rl_callback_sigcleanup: a new application function that can clean up and
unset any state set by readline's callback mode. Intended to be used
after a signal.
j. If an incremental search string has its last character removed with DEL, the
resulting empty search string no longer matches the previous line.
k. If readline reads a history file that begins with `#' (or the value of
the history comment character) and has enabled history timestamps, the
history entries are assumed to be delimited by timestamps. This allows
multi-line history entries.
l. Readline now throws an error if it parses a key binding without a
terminating `:' or whitespace.
m. The default binding for ^W in vi mode now uses word boundaries specified
by Posix (vi-unix-word-rubout is bindable command name).
n. rl_clear_visible_line: new application-callable function; clears all
screen lines occupied by the current visible readline line.
o. rl_tty_set_echoing: application-callable function that controls whether
or not readline thinks it is echoing terminal output.
p. Handle >| and strings of digits preceding and following redirection
specifications as single tokens when tokenizing the line for history
expansion.
q. Fixed a bug with displaying completions when the prefix display length
is greater than the length of the completions to be displayed.
r. The :p history modifier now applies to the entire line, so any expansion
specifying :p causes the line to be printed instead of expanded.
s. New application-callable function: rl_pending_signal(): returns the signal
number of any signal readline has caught but not yet handled.
t. New application-settable variable: rl_persistent_signal_handlers: if set
to a non-zero value, readline will enable the readline-6.2 signal handler
behavior in callback mode: handlers are installed when
rl_callback_handler_install is called and removed removed when a complete
line has been read.
This is a terse description of the new features added to bash-4.3 since
the release of bash-4.2. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The `helptopic' completion action now maps to all the help topics, not just
the shell builtins.
b. The `help' builtin no longer does prefix substring matching first, so
`help read' does not match `readonly', but will do it if exact string
matching fails.
c. The shell can be compiled to not display a message about processes that
terminate due to SIGTERM.
d. Non-interactive shells now react to the setting of checkwinsize and set
LINES and COLUMNS after a foreground job exits.
e. There is a new shell option, `globasciiranges', which, when set to on,
forces globbing range comparisons to use character ordering as if they
were run in the C locale.
f. There is a new shell option, `direxpand', which makes filename completion
expand variables in directory names in the way bash-4.1 did.
g. In Posix mode, the `command' builtin does not change whether or not a
builtin it shadows is treated as an assignment builtin.
h. The `return' and `exit' builtins accept negative exit status arguments.
i. The word completion code checks whether or not a filename containing a
shell variable expands to a directory name and appends `/' to the word
as appropriate. The same code expands shell variables in command names
when performing command completion.
j. In Posix mode, it is now an error to attempt to define a shell function
with the same name as a Posix special builtin.
k. When compiled for strict Posix conformance, history expansion is disabled
by default.
l. The history expansion character (!) does not cause history expansion when
followed by the closing quote in a double-quoted string.
m. `complete' and its siblings compgen/compopt now takes a new `-o noquote'
option to inhibit quoting of the completions.
n. Setting HISTSIZE to a value less than zero causes the history list to be
unlimited (setting it 0 zero disables the history list).
o. Setting HISTFILESIZE to a value less than zero causes the history file size
to be unlimited (setting it to 0 causes the history file to be truncated
to zero size).
p. The `read' builtin now skips NUL bytes in the input.
q. There is a new `bind -X' option to print all key sequences bound to Unix
commands.
r. When in Posix mode, `read' is interruptible by a trapped signal. After
running the trap handler, read returns 128+signal and throws away any
partially-read input.
s. The command completion code skips whitespace and assignment statements
before looking for the command name word to be completed.
t. The build process has a new mechanism for constructing separate help files
that better reflects the current set of compilation options.
u. The -nt and -ot options to test now work with files with nanosecond
timestamp resolution.
v. The shell saves the command history in any shell for which history is
enabled and HISTFILE is set, not just interactive shells.
w. The shell has `nameref' variables and new -n(/+n) options to declare and
unset to use them, and a `test -R' option to test for them.
x. The shell now allows assigning, referencing, and unsetting elements of
indexed arrays using negative subscripts (a[-1]=2, echo ${a[-1]}) which
count back from the last element of the array.
y. The {x}<word redirection feature now allows words like {array[ind]} and
can use variables with special meanings to the shell (e.g., BASH_XTRACEFD).
z. There is a new CHILD_MAX special shell variable; its value controls the
number of exited child statues the shell remembers.
aa. There is a new configuration option (--enable-direxpand-default) that
causes the `direxpand' shell option to be enabled by default.
bb. Bash does not do anything special to ensure that the file descriptor
assigned to X in {x}<foo remains open after the block containing it
completes.
cc. The `wait' builtin has a new `-n' option to wait for the next child to
change status.
dd. The `printf' %(...)T format specifier now uses the current time if no
argument is supplied.
ee. There is a new variable, BASH_COMPAT, that controls the current shell
compatibility level.
ff. The `popd' builtin now treats additional arguments as errors.
gg. The brace expansion code now treats a failed sequence expansion as a
simple string and will continue to expand brace terms in the remainder
of the word.
hh. Shells started to run process substitutions now run any trap set on EXIT.
ii. The fc builtin now interprets -0 as the current command line.
jj. Completing directory names containing shell variables now adds a trailing
slash if the expanded result is a directory.
kk. `cd' has a new `-@' option to browse a file's extended attributes on
systems that support O_XATTR.
ll. The test/[/[[ `-v variable' binary operator now understands array
references.
2. New Features in Readline
a. Readline is now more responsive to SIGHUP and other fatal signals when
reading input from the terminal or performing word completion but no
longer attempts to run any not-allowable functions from a signal handler
context.
b. There are new bindable commands to search the history for the string of
characters between the beginning of the line and the point
(history-substring-search-forward, history-substring-search-backward)
c. Readline allows quoted strings as the values of variables when setting
them with `set'. As a side effect, trailing spaces and tabs are ignored
when setting a string variable's value.
d. The history library creates a backup of the history file when writing it
and restores the backup on a write error.
e. New application-settable variable: rl_filename_stat_hook: a function called
with a filename before using it in a call to stat(2). Bash uses it to
expand shell variables so things like $HOME/Downloads have a slash
appended.
f. New bindable function `print-last-kbd-macro', prints the most-recently-
defined keyboard macro in a reusable format.
g. New user-settable variable `colored-stats', enables use of colored text
to denote file types when displaying possible completions (colored analog
of visible-stats).
h. New user-settable variable `keyseq-timout', acts as an inter-character
timeout when reading input or incremental search strings.
i. New application-callable function: rl_clear_history. Clears the history list
and frees all readline-associated private data.
j. New user-settable variable, show-mode-in-prompt, adds a characters to the
beginning of the prompt indicating the current editing mode.
k. New application-settable variable: rl_input_available_hook; function to be
called when readline detects there is data available on its input file
descriptor.
l. Readline calls an application-set event hook (rl_event_hook) after it gets
a signal while reading input (read returns -1/EINTR but readline does not
handle the signal immediately) to allow the application to handle or
otherwise note it.
m. If the user-settable variable `history-size' is set to a value less than
0, the history list size is unlimited.
n. New application-settable variable: rl_signal_event_hook; function that is
called when readline is reading terminal input and read(2) is interrupted
by a signal. Currently not called for SIGHUP or SIGTERM.
o. rl_change_environment: new application-settable variable that controls
whether or not Readline modifies the environment (currently readline
modifies only LINES and COLUMNS).
1. New Features in Bash
a. `exec -a foo' now sets $0 to `foo' in an executable shell script without a
leading #!.
b. Subshells begun to execute command substitutions or run shell functions or
builtins in subshells do not reset trap strings until a new trap is
specified. This allows $(trap) to display the caller's traps and the
trap strings to persist until a new trap is set.
c. `trap -p' will now show signals ignored at shell startup, though their
disposition still cannot be modified.
d. $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences.
e. declare/typeset has a new `-g' option, which creates variables in the
global scope even when run in a shell function.
f. test/[/[[ have a new -v variable unary operator, which returns success if
`variable' has been set.
g. Posix parsing changes to allow `! time command' and multiple consecutive
instances of `!' (which toggle) and `time' (which have no cumulative
effect).
h. Posix change to allow `time' as a command by itself to print the elapsed
user, system, and real times for the shell and its children.
j. $((...)) is always parsed as an arithmetic expansion first, instead of as
a potential nested command substitution, as Posix requires.
k. A new FUNCNEST variable to allow the user to control the maximum shell
function nesting (recursive execution) level.
l. The mapfile builtin now supplies a third argument to the callback command:
the line about to be assigned to the supplied array index.
m. The printf builtin has a new %(fmt)T specifier, which allows time values
to use strftime-like formatting.
n. There is a new `compat41' shell option.
o. The cd builtin has a new Posix-mandated `-e' option.
p. Negative subscripts to indexed arrays, previously errors, now are treated
as offsets from the maximum assigned index + 1.
q. Negative length specifications in the ${var:offset:length} expansion,
previously errors, are now treated as offsets from the end of the variable.
r. Parsing change to allow `time -p --'.
s. Posix-mode parsing change to not recognize `time' as a keyword if the
following token begins with a `-'. This means no more Posix-mode
`time -p'. Posix interpretation 267.
t. There is a new `lastpipe' shell option that runs the last command of a
pipeline in the current shell context. The lastpipe option has no
effect if job control is enabled.
u. History expansion no longer expands the `$!' variable expansion.
v. Posix mode shells no longer exit if a variable assignment error occurs
with an assignment preceding a command that is not a special builtin.
w. Non-interactive mode shells exit if -u is enabled and an attempt is made
to use an unset variable with the % or # expansions, the `//', `^', or
`,' expansions, or the parameter length expansion.
x. Posix-mode shells use the argument passed to `.' as-is if a $PATH search
fails, effectively searching the current directory. Posix-2008 change.
2. New Features in Readline
a. The history library does not try to write the history filename in the
current directory if $HOME is unset. This closes a potential security
problem if the application does not specify a history filename.
b. New bindable variable `completion-display-width' to set the number of
columns used when displaying completions.
c. New bindable variable `completion-case-map' to cause case-insensitive
completion to treat `-' and `_' as identical.
d. There are new bindable vi-mode command names to avoid readline's case-
insensitive matching not allowing them to be bound separately.
e. New bindable variable `menu-complete-display-prefix' causes the menu
completion code to display the common prefix of the possible completions
before cycling through the list, instead of after.
This document details the changes between this version, bash-4.1-rc,
and the previous version, bash-4.1-beta.
1. Changes to Bash
a. Fixed a bug that caused printf to not return a partial value when it
encountered an error while converting an integer argument.
b. Fixed a bug that caused setting one of the compatNN options to not
turn off the others.
c. The (undocumented) --wordexp option is no longer included by default.
d. Fixed a bug in conditional command execution that caused it to not
correctly ignore the exit status under certain circumstances.
e. Added a configure-time check for correctly-working asprintf/snprintf.
f. Fixed some problems with line number calculation and display when sourcing
a file in an interactive shell.
g. Fixed a bug that caused the shell to crash when using `declare -A foo=bar'.
h. Fixed a bug that caused an off-by-one error when calculating the directories
to display with the PROMPT_DIRTRIM option.
2. Changes to Readline
a. Fixed a bug that caused applications using the callback interface to not
react to SIGINT (or other signals) until another character arrived.
------------------------------------------------------------------------------
This document details the changes between this version, bash-4.1-beta,
and the previous version, bash-4.1-alpha.
1. Changes to Bash
a. Fixed a bug in mapfile that caused the shell to crash if it was passed the
name of an associative array.
b. Fixed a bug that caused the shell to incorrectly split case patterns if
they contained characters in $IFS.
c. Fixed a bug that caused the shell to set $? to the wrong value when using
a construct ending with a variable assignment with set -x enabled and PS4
containing a command substitution.
d. Fixed a bug that caused the shell to read commands incorrectly if an
expansion error occurred under certain conditions in a user-specified
subshell.
e. Fixed a bug that caused the shell to set $? incorrectly if a parse error
occurred in an evaluation context ("eval", trap command, dot script, etc.)
f. Fixed a bug that caused the shell to attempt command substitution
completion within a single-quoted string.
g. Fixed a bug that caused the shell to insert an extra single quote during
word completion.
h. Fixed a bug that caused the shell to crash if invoked with the environment
variable EMACS having a null value.
i. Fixed a bug that caused bash to incorrectly report the presence of new
mail in a `maildir' environment.
j. Fixed a bug that caused the shell to not recognize a here-document ending
delimiter inside a command substitution.
k. Fixed a bug that caused the shell to crash when a a dynamic array variable
was assigned a scalar value.
2. Changes to Readline
3. New Features in Bash
a. The mapfile/readarray builtin no longer stores the commands it invokes via
callbacks in the history list.
b. There is a new `compat40' shopt option.
c. The < and > operators to [[ do string comparisons using the current locale
only if the compatibility level is greater than 40 (set to 41 by default).
4. New Features in Readline
------------------------------------------------------------------------------
This document details the changes between this version, bash-4.1-alpha,
and the previous version, bash-4.0-release.
1. Changes to Bash
a. Fixed bugs in the parser involving new parsing of the commands contained
in command substitution when the substitution is read.
b. Fixed a bug that caused the shell to dump core when performing programmable
completion using a shell function.
c. Fixed a bug in `mapfile' that caused it to invoke callbacks at the wrong
time.
d. Fixed a bug that caused the shell to dump core when listing jobs in the
`exit' builtin.
e. Fixed several bugs encountered when reading subscripts in associative
array assignments and expansions.
f. Fixed a bug that under some circumstances caused an associative array to
be converted to an indexed array.
g. Fixed a bug that caused syntax errors and SIGINT interrupts to not set
$? to a value > 128.
h. Fixed a bug that caused the shell to remove FIFOs associated with process
substitution inside shell functions.
i. Fixed a bug that caused terminal attributes to not be reset when the
`read' builtin timed out.
j. Fixed a bug in brace expansion that caused unwanted zero padding of the
expanded terms.
k. Fixed a bug that prevented the |& construct from working as intended when
used with a simple command with additional redirections.
l. Fixed a bug with the case statment ;& terminator that caused the shell to
dereference a NULL pointer.
m. Fixed a bug that caused assignment statements or redirections preceding
a simple command name to inhibit alias expansion.
n. Fixed the behavior of `set -u' to conform to the latest Posix interpretation:
every expansion of an unset variable except $@ and $* will cause the
shell to exit.
o. Fixed a bug that caused double-quoted expansions of $* inside word
expansions like ${x#$*} to not expand properly when $IFS is empty.
p. Fixed a bug that caused traps to set $LINENO to the wrong value when they
execute.
q. Fixed a bug that caused off-by-one errors when computing history lines in
the `fc' builtin.
r. Fixed a bug that caused some terminating signals to not exit the shell
quickly enough, forcing the kernel to send the signal (e.g., SIGSEGV)
multiple times.
s. Fixed a bug that caused the shell to attempt to add empty lines to the
history list when reading here documents.
t. Made some internal changes that dramatically speeds up sequential indexed
array access.
u. Fixed a bug that caused the shell to write past the end of a string when
completing a double-quoted string ending in a backslash.
v. Fixed a bug that caused the shell to replace too many characters when a
pattern match was null in a ${foo//bar} expansion.
w. Fixed bugs in the expansion of ** that caused duplicate directory names
and the contents of the current directory to be omitted.
x. Fixed a bug that caused $? to not be set correctly when referencing an
unset variable with set -u and set -e enabled.
y. Fixed a bug caused by executing an external program from the DEBUG trap
while a pipeline was running. The effect was to disturb the pipeline
state, occasionally causing it to hang.
z. Fixed a bug that caused the ** glob expansion to dump core if it
encountered an unsearchable directory.
aa. Fixed a bug that caused `command -v' and `command -V' to not honor the
path set by the -p option.
bb. Fixed a bug that caused brace expansion to take place too soon in some
compound array assignments.
cc. Fixed a bug that caused programmable completion functions' changes to
READLINE_POINT to not be reflected back to readline.
dd. Fixed a bug that caused the shell to dump core if a trap was executed
during a shell assignment statement.
ee. Fixed an off-by-one error when computing the number of positional
parameters for the ${@:0:n} expansion.
ff. Fixed a problem with setting COMP_CWORD for programmable completion
functions that could leave it set to -1.
gg. Fixed a bug that caused the ERR trap to be triggered in some cases where
`set -e' would not have caused the shell to exit.
hh. Fixed a bug that caused changes made by `compopt' to not persist past the
completion function in which compopt was executed.
ii. Fixed a bug that caused the list of hostname completions to not be cleared
when HOSTNAME was unset.
jj. Fixed a bug that caused variable expansion in here documents to look in
any temporary environment.
kk. Bash and readline can now convert file names between precomposed and
decomposed Unicode on Mac OS X ("keyboard" and file system forms,
respectively). This affects filename completion (using new
rl_filename_rewrite_hook), globbing, and readline redisplay.
ll. The ERR and EXIT traps now see a non-zero value for $? when a parser
error after set -e has been enabled causes the shell to exit.
mm. Fixed a bug that in brace expansion that caused zero-prefixed terms to
not contain the correct number of digits.
nn. Fixed a bug that caused the shell to free non-allocated memory when
unsetting an associative array which had had a value implicitly assigned
to index "0".
oo. Fixed a memory leak in the ${!prefix@} expansion.
pp. Fixed a bug that caused printf to not correctly report all write errors.
qq. Fixed a bug that caused single and double quotes to act as delimiters
when splitting a command line into words for programmable completion.
rr. Fixed a bug that caused ** globbing that caused **/path/* to match every
directory, not just those matching `path'.
ss. Fixed a bug that caused the shell to dump core when running `help' without
arguments if the terminal width was fewer than 7 characters.
2. Changes to Readline
a. The SIGWINCH signal handler now avoids calling the redisplay code if
one arrives while in the middle of redisplay.
b. Changes to the timeout code to make sure that timeout values greater
than one second are handled better.
c. Fixed a bug in the redisplay code that was triggered by a prompt
containing invisible characters exactly the width of the screen.
d. Fixed a bug in the redisplay code encountered when running in horizontal
scroll mode.
e. Fixed a bug that prevented menu completion from properly completing
filenames.
f. Fixed a redisplay bug caused by a multibyte character causing a line to
wrap.
g. Fixed a bug that caused key sequences of two characters to not be
recognized when a longer sequence identical in the first two characters
was bound.
h. Fixed a bug that caused history expansion to be attempted on $'...'
single-quoted strings.
i. Fixed a bug that caused incorrect redisplay when the prompt contained
multibyte characters in an `invisible' sequence bracketed by \[ and
\].
j. Fixed a bug that caused history expansion to short-circuit after
encountering a multibyte character.
3. New Features in Bash
a. Here-documents within $(...) command substitutions may once more be
delimited by the closing right paren, instead of requiring a newline.
b. Bash's file status checks (executable, readable, etc.) now take file
system ACLs into account on file systems that support them.
c. Bash now passes environment variables with names that are not valid
shell variable names through into the environment passed to child
processes.
d. The `execute-unix-command' readline function now attempts to clear and
reuse the current line rather than move to a new one after the command
executes.
e. `printf -v' can now assign values to array indices.
f. New `complete -E' and `compopt -E' options that work on the "empty"
completion: completion attempted on an empty command line.
g. New complete/compgen/compopt -D option to define a `default' completion:
a completion to be invoked on command for which no completion has been
defined. If this function returns 124, programmable completion is
attempted again, allowing a user to dynamically build a set of completions
as completion is attempted by having the default completion function
install individual completion functions each time it is invoked.
h. When displaying associative arrays, subscripts are now quoted.
i. Changes to dabbrev-expand to make it more `emacs-like': no space appended
after matches, completions are not sorted, and most recent history entries
are presented first.
j. The [[ and (( commands are now subject to the setting of `set -e' and the
ERR trap.
k. The source/. builtin now removes NUL bytes from the file before attempting
to parse commands.
l. There is a new configuration option (in config-top.h) that forces bash to
forward all history entries to syslog.
m. A new variable $BASHOPTS to export shell options settable using `shopt' to
child processes.
n. There is a new confgure option that forces the extglob option to be
enabled by default.
o. New variable $BASH_XTRACEFD; when set to an integer bash will write xtrace
output to that file descriptor.
p. If the optional left-hand-side of a redirection is of the form {var}, the
shell assigns the file descriptor used to $var or uses $var as the file
descriptor to move or close, depending on the redirection operator.
q. The < and > operators to the [[ conditional command now do string
comparison according to the current locale.
r. Programmable completion now uses the completion for `b' instead of `a'
when completion is attempted on a line like: a $(b c.
s. Force extglob on temporarily when parsing the pattern argument to
the == and != operators to the [[ command, for compatibility.
t. Changed the behavior of interrupting the wait builtin when a SIGCHLD is
received and a trap on SIGCHLD is set to be Posix-mode only.
u. The read builtin has a new `-N nchars' option, which reads exactly NCHARS
characters, ignoring delimiters like newline.
4. New Features in Readline
a. New bindable function: menu-complete-backward.
b. In the vi insertion keymap, C-n is now bound to menu-complete by default,
and C-p to menu-complete-backward.
c. When in vi command mode, repeatedly hitting ESC now does nothing, even
when ESC introduces a bound key sequence. This is closer to how
historical vi behaves.
d. New bindable function: skip-csi-sequence. Can be used as a default to
consume key sequences generated by keys like Home and End without having
to bind all keys.
e. New application-settable function: rl_filename_rewrite_hook. Can be used
to rewite or modify filenames read from the file system before they are
compared to the word to be completed.
f. New bindable variable: skip-completed-text, active when completing in the
middle of a word. If enabled, it means that characters in the completion
that match characters in the remainder of the word are "skipped" rather
than inserted into the line.
g. The pre-readline-6.0 version of menu completion is available as
"old-menu-complete" for users who do not like the readline-6.0 version.
h. New bindable variable: echo-control-characters. If enabled, and the
tty ECHOCTL bit is set, controls the echoing of characters corresponding
to keyboard-generated signals.
i. New bindable variable: enable-meta-key. Controls whether or not readline
sends the smm/rmm sequences if the terminal indicates it has a meta key
that enables eight-bit characters.
1. New Features in Bash
a. When using substring expansion on the positional parameters, a starting
index of 0 now causes $0 to be prefixed to the list.
b. The `help' builtin now prints its columns with entries sorted vertically
rather than horizontally.
c. There is a new variable, $BASHPID, which always returns the process id of
the current shell.
d. There is a new `autocd' option that, when enabled, causes bash to attempt
to `cd' to a directory name that is supplied as the first word of a
simple command.
e. There is a new `checkjobs' option that causes the shell to check for and
report any running or stopped jobs at exit.
f. The programmable completion code exports a new COMP_TYPE variable, set to
a character describing the type of completion being attempted.
g. The programmable completion code exports a new COMP_KEY variable, set to
the character that caused the completion to be invoked (e.g., TAB).
h. If creation of a child process fails due to insufficient resources, bash
will try again several times before reporting failure.
i. The programmable completion code now uses the same set of characters as
readline when breaking the command line into a list of words.
j. The block multiplier for the ulimit -c and -f options is now 512 when in
Posix mode, as Posix specifies.
k. Changed the behavior of the read builtin to save any partial input received
in the specified variable when the read builtin times out. This also
results in variables specified as arguments to read to be set to the empty
string when there is no input available. When the read builtin times out,
it returns an exit status greater than 128.
l. The shell now has the notion of a `compatibility level', controlled by
new variables settable by `shopt'. Setting this variable currently
restores the bash-3.1 behavior when processing quoted strings on the rhs
of the `=~' operator to the `[[' command.
m. The `ulimit' builtin now has new -b (socket buffer size) and -T (number
of threads) options.
n. The -p option to `declare' now displays all variable values and attributes
(or function values and attributes if used with -f).
o. There is a new `compopt' builtin that allows completion functions to modify
completion options for existing completions or the completion currently
being executed.
p. The `read' builtin has a new -i option which inserts text into the reply
buffer when using readline.
q. A new `-E' option to the complete builtin allows control of the default
behavior for completion on an empty line.
r. There is now limited support for completing command name words containing
globbing characters.
s. Changed format of internal help documentation for all builtins to roughly
follow man page format.
t. The `help' builtin now has a new -d option, to display a short description,
and a -m option, to print help information in a man page-like format.
u. There is a new `mapfile' builtin to populate an array with lines from a
given file. The name `readarray' is a synonym.
v. If a command is not found, the shell attempts to execute a shell function
named `command_not_found_handle', supplying the command words as the
function arguments.
w. There is a new shell option: `globstar'. When enabled, the globbing code
treats `**' specially -- it matches all directories (and files within
them, when appropriate) recursively.
x. There is a new shell option: `dirspell'. When enabled, the filename
completion code performs spelling correction on directory names during
completion.
y. The `-t' option to the `read' builtin now supports fractional timeout
values.
z. Brace expansion now allows zero-padding of expanded numeric values and
will add the proper number of zeroes to make sure all values contain the
same number of digits.
aa. There is a new bash-specific bindable readline function: `dabbrev-expand'.
It uses menu completion on a set of words taken from the history list.
bb. The command assigned to a key sequence with `bind -x' now sets two new
variables in the environment of the executed command: READLINE_LINE_BUFFER
and READLINE_POINT. The command can change the current readline line
and cursor position by modifying READLINE_LINE_BUFFER and READLINE_POINT,
respectively.
cc. There is a new &>> redirection operator, which appends the standard output
and standard error to the named file.
dd. The parser now understands `|&' as a synonym for `2>&1 |', which redirects
the standard error for a command through a pipe.
ee. The new `;&' case statement action list terminator causes execution to
continue with the action associated with the next pattern in the
statement rather than terminating the command.
ff. The new `;;&' case statement action list terminator causes the shell to
test the next set of patterns after completing execution of the current
action, rather than terminating the command.
gg. The shell understands a new variable: PROMPT_DIRTRIM. When set to an
integer value greater than zero, prompt expansion of \w and \W will
retain only that number of trailing pathname components and replace
the intervening characters with `...'.
hh. There are new case-modifying word expansions: uppercase (^[^]) and
lowercase (,[,]). They can work on either the first character or
array element, or globally. They accept an optional shell pattern
that determines which characters to modify. There is an optionally-
configured feature to include capitalization operators.
ii. The shell provides associative array variables, with the appropriate
support to create, delete, assign values to, and expand them.
jj. The `declare' builtin now has new -l (convert value to lowercase upon
assignment) and -u (convert value to uppercase upon assignment) options.
There is an optionally-configurable -c option to capitalize a value at
assignment.
kk. There is a new `coproc' reserved word that specifies a coprocess: an
asynchronous command run with two pipes connected to the creating shell.
Coprocs can be named. The input and output file descriptors and the
PID of the coprocess are available to the calling shell in variables
with coproc-specific names.
ll. A value of 0 for the -t option to `read' now returns success if there is
input available to be read from the specified file descriptor.
mm. CDPATH and GLOBIGNORE are ignored when the shell is running in privileged
mode.
nn. New bindable readline functions shell-forward-word and shell-backward-word,
which move forward and backward words delimited by shell metacharacters
and honor shell quoting.
oo. New bindable readline functions shell-backward-kill-word and shell-kill-word
which kill words backward and forward, but use the same word boundaries
as shell-forward-word and shell-backward-word.
2. New Features in Readline
a. A new variable, rl_sort_completion_matches; allows applications to inhibit
match list sorting (but beware: some things don't work right if
applications do this).
b. A new variable, rl_completion_invoking_key; allows applications to discover
the key that invoked rl_complete or rl_menu_complete.
c. The functions rl_block_sigint and rl_release_sigint are now public and
available to calling applications who want to protect critical sections
(like redisplay).
d. The functions rl_save_state and rl_restore_state are now public and
available to calling applications; documented rest of readline's state
flag values.
e. A new user-settable variable, `history-size', allows setting the maximum
number of entries in the history list.
f. There is a new implementation of menu completion, with several improvements
over the old; the most notable improvement is a better `completions
browsing' mode.
g. The menu completion code now uses the rl_menu_completion_entry_function
variable, allowing applications to provide their own menu completion
generators.
h. There is support for replacing a prefix of a pathname with a `...' when
displaying possible completions. This is controllable by setting the
`completion-prefix-display-length' variable. Matches with a common prefix
longer than this value have the common prefix replaced with `...'.
i. There is a new `revert-all-at-newline' variable. If enabled, readline will
undo all outstanding changes to all history lines when `accept-line' is
executed.
j. If the kernel supports it, readline displays special characters
corresponding to a keyboard-generated signal when the signal is received.
This document details the changes between this version, bash-3.2-release,
and the previous version, bash-3.2-beta.
1. Changes to Bash
a. Fixed a bug that caused the temporary environment passed to a command to
affect the shell's environment under certain circumstances.
b. Fixed a bug in the printf builtin that caused the %q format specifier to
ignore empty string arguments.
c. Improved multibyte character environment detection at configuration time.
d. Fixed a bug in the read builtin that left spurious escape characters in the
input after processing backslashes when assigning to an array variable.
2. Changes to Readline
a. Fixed a redisplay bug that occurred in multibyte-capable locales when the
prompt was one character longer than the screen width.
------------------------------------------------------------------------------
This document details the changes between this version, bash-3.2-beta,
and the previous version, bash-3.2-alpha.
1. Changes to Bash
a. Changed the lexical analyzer to treat locale-specific blank characters as
white space.
b. Fixed a bug in command printing to avoid confusion between redirections and
process substitution.
c. Fixed problems with cross-compiling originating from inherited environment
variables.
d. Added write error reporting to printf builtin.
e. Fixed a bug in the variable expansion code that could cause a core dump in
a multi-byte locale.
f. Fixed a bug that caused substring expansion of a null string to return
incorrect results.
g. BASH_COMMAND now retains its previous value while executing commands as the
result of a trap, as the documentation states.
2. Changes to Readline
a. Fixed a bug with prompt redisplay in a multi-byte locale to avoid redrawing
the prompt and input line multiple times.
b. Fixed history expansion to not be confused by here-string redirection.
c. Readline no longer treats read errors by converting them to newlines, as
it does with EOF. This caused partial lines to be returned from readline().
------------------------------------------------------------------------------
This document details the changes between this version, bash-3.2-alpha,
and the previous version, bash-3.1-release.
1. Changes to Bash
a. Fixed a source bug that caused the minimal configuration to not compile.
b. Fixed memory leaks in error handling for the `read' builtin.
c. Changed the [[ and (( compound commands to set PIPESTATUS with their exit
status.
d. Fixed some parsing problems with compound array assignments.
e. Added additional configuration changes for: NetBSD (incomplete multibyte
character support)
f. Fixed two bugs with local array variable creation when shadowing a variable
of the same name from a previous context.
g. Fixed the `read' builtin to restore the correct set of completion functions
if a timeout occurs.
h. Added code to defer the initialization of HISTSIZE (and its stifling of the
history list) until the history file is loaded, allowing a startup file to
override the default value.
i. Tightened up the arithmetic expression parsing to produce better error
messages when presented with invalid operators.
j. Fixed the cross-compilation support to build the signal list at shell
invocation rather than compile time if cross-compiling.
k. Fixed multibyte support for non-gcc compilers (or compilers that do not
allow automatic array variable sizing based on a non-constant value).
l. Several fixes to the code that manages the list of terminated jobs and
their exit statuses, and the list of active and recently-terminated jobs
to avoid pid aliasing/wraparound and allocation errors.
m. Fixed a problem that allowed scripts to die due to SIGINT while waiting
for children, even when started in the background or otherwise ignoring
SIGINT.
n. Fixed a bug that caused shells invoked as -/bin/bash from not being
recognized as login shells.
o. Fixed a problem that caused shells in the background to give the terminal
to a process group other than the foreground shell process group.
p. Fixed a problem with extracting the `varname' in ${#varname}.
q. Fixed the code that handles SIGQUIT to not exit immediately -- thereby
calling functions that may not be called in a signal handler context --
but set a flag and exit afterward (like SIGINT).
r. Changed the brace expansion code to skip over braces that don't begin a
valid matched brace expansion construct.
s. Fixed `typeset' and `declare' to not require that their shell function
operands to be valid shell identifiers.
t. Changed `test' to use access(2) with a temporary uid/euid swap when testing
file attributes and running setuid, and access(2) in most other cases.
u. Changed completion code to not attempt command name completion on a line
consisting solely of whitespace when no_empty_command_completion is set.
v. The `hash' builtin now prints nothing in posix mode when the hash table is
empty, and prints a message to that effect to stdout instead of stderr
when not in posix mode.
w. Fixed a bug in the extended pattern matching code that caused it to fail to
match periods with certain patterns.
x. Fixed a bug that caused the shell to dump core when performing filename
generation in directories with thousands of files.
y. Returned to the original Bourne shell rules for parsing ``: no recursive
parsing of embedded quoted strings or ${...} constructs.
z. The inheritence of the DEBUG, RETURN, and ERR traps is now dependent only
on the settings of the `functrace' and `errtrace' shell options, rather
than whether or not the shell is in debugging mode.
aa. Fixed a problem with $HOME being converted to ~ in the expansion of
members of the DIRSTACK array.
bb. Fixed a problem with quoted arguments to arithmetic expansions in certain
constructs.
cc. The command word completion code now no longer returns matching directories
while searching $PATH.
dd. Fixed a bug with zero-padding and precision handling in snprintf()
replacement.
ee. Fixed a bug that caused the command substitution code not to take embedded
shell comments into account.
ff. Fixed a bug that caused $((...);(...)) to be misinterpreted as an
arithmetic substitution.
gg. Fixed a bug in the prompt expansion code that inappropriately added a
\001 before a \002 under certain circumstances.
hh. Fixed a bug that caused `unset LANG' to not properly reset the locale
(previous versions would set the locale back to what it was when bash
was started rather than the system's "native" locale).
ii. Fixed a bug that could cause file descriptors > 10 to not be closed even
when closed explicitly by a script.
jj. Fixed a bug that caused single quotes to be stripped from ANSI-C quoting
inside double-quoted command substitutions.
kk. Fixed a bug that could cause core dumps when `return' was executed as the
last element of a pipeline inside a shell function.
ll. Fixed a bug that caused DEBUG trap strings to overwrite commands stored in
the jobs list.
2. Changes to Readline
a. Fixed a problem that caused segmentation faults when using readline in
callback mode and typing consecutive DEL characters on an empty line.
b. Fixed several redisplay problems with multibyte characters, all having to
do with the different code paths and variable meanings between single-byte
and multibyte character redisplay.
c. Fixed a problem with key sequence translation when presented with the
sequence \M-\C-x.
d. Fixed a problem that prevented the `a' command in vi mode from being
undone and redone properly.
e. Fixed a problem that prevented empty inserts in vi mode from being undone
properly.
f. Fixed a problem that caused readline to initialize with an incorrect idea
of whether or not the terminal can autowrap.
g. Fixed output of key bindings (like bash `bind -p') to honor the setting of
convert-meta and use \e where appropriate.
h. Changed the default filename completion function to call the filename
dequoting function if the directory completion hook isn't set. This means
that any directory completion hooks need to dequote the directory name,
since application-specific hooks need to know how the word was quoted,
even if no other changes are made.
i. Fixed a bug with creating the prompt for a non-interactive search string
when there are non-printing characters in the primary prompt.
j. Fixed a bug that caused prompts with invisible characters to be redrawn
multiple times in a multibyte locale.
k. Fixed a bug that could cause the key sequence scanning code to return the
wrong function.
l. Fixed a problem with the callback interface that caused it to fail when
using multi-character keyboard macros.
m. Fixed a bug that could cause a core dump when an edited history entry was
re-executed under certain conditions.
n. Fixed a bug that caused readline to reference freed memory when attmpting
to display a portion of the prompt.
3. New Features in Bash
a. Changed the parameter pattern replacement functions to not anchor the
pattern at the beginning of the string if doing global replacement - that
combination doesn't make any sense.
b. When running in `word expansion only' mode (--wordexp option), inhibit
process substitution.
c. Loadable builtins now work on MacOS X 10.[34].
d. Shells running in posix mode no longer set $HOME, as POSIX requires.
e. The code that checks for binary files being executed as shell scripts now
checks only for NUL rather than any non-printing character.
f. Quoting the string argument to the [[ command's =~ operator now forces
string matching, as with the other pattern-matching operators.
4. New Features in Readline
a. Calling applications can now set the keyboard timeout to 0, allowing
poll-like behavior.
b. The value of SYS_INPUTRC (configurable at compilation time) is now used as
the default last-ditch startup file.
c. The history file reading functions now allow windows-like \r\n line
terminators.
This is a terse description of the new features added to bash-3.1 since
the release of bash-3.0. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Bash now understands LC_TIME as a special variable so that time display
tracks the current locale.
b. BASH_ARGC, BASH_ARGV, BASH_SOURCE, and BASH_LINENO are no longer created
as `invisible' variables and may not be unset.
c. In POSIX mode, if `xpg_echo' option is enabled, the `echo' builtin doesn't
try to interpret any options at all, as POSIX requires.
d. The `bg' builtin now accepts multiple arguments, as POSIX seems to specify.
e. Fixed vi-mode word completion and glob expansion to perform tilde
expansion.
f. The `**' mathematic exponentiation operator is now right-associative.
g. The `ulimit' builtin has new options: -i (max number of pending signals),
-q (max size of POSIX message queues), and -x (max number of file locks).
h. A bare `%' once again expands to the current job when used as a job
specifier.
i. The `+=' assignment operator (append to the value of a string or array) is
now supported for assignment statements and arguments to builtin commands
that accept assignment statements.
j. BASH_COMMAND now preserves its value when a DEBUG trap is executed.
k. The `gnu_errfmt' option is enabled automatically if the shell is running
in an emacs terminal window.
l. New configuration option: --single-help-strings. Causes long help text
to be written as a single string; intended to ease translation.
m. The COMP_WORDBREAKS variable now causes the list of word break characters
to be emptied when the variable is unset.
n. An unquoted expansion of $* when $IFS is empty now causes the positional
parameters to be concatenated if the expansion doesn't undergo word
splitting.
o. Bash now inherits $_ from the environment if it appears there at startup.
p. New shell option: nocasematch. If non-zero, shell pattern matching ignores
case when used by `case' and `[[' commands.
q. The `printf' builtin takes a new option: -v var. That causes the output
to be placed into var instead of on stdout.
r. By default, the shell no longer reports processes dying from SIGPIPE.
s. Bash now sets the extern variable `environ' to the export environment it
creates, so C library functions that call getenv() (and can't use the
shell-provided replacement) get current values of environment variables.
t. A new configuration option, `--enable-strict-posix-default', which will
build bash to be POSIX conforming by default.
u. If compiled for strict POSIX conformance, LINES and COLUMNS may now
override the true terminal size.
2. New Features in Readline
a. The key sequence sent by the keypad `delete' key is now automatically
bound to delete-char.
b. A negative argument to menu-complete now cycles backward through the
completion list.
c. A new bindable readline variable: bind-tty-special-chars. If non-zero,
readline will bind the terminal special characters to their readline
equivalents when it's called (on by default).
d. New bindable command: vi-rubout. Saves deleted text for possible
reinsertion, as with any vi-mode `text modification' command; `X' is bound
to this in vi command mode.
e. A new external application-controllable variable that allows the LINES
and COLUMNS environment variables to set the window size regardless of
what the kernel returns: rl_prefer_env_winsize
rillig
maya
leot
ryoon
jperkin
wiz
rodent
dholland
christos
tron
chopps
bsiegert
tcort
spz
obache
joerg
garbled
minskim