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@@ -1,3 +1,850 @@ +This document details the changes between this version, bash-4.3-release, and +the previous version, bash-4.3-rc2. + +1. Changes to Bash + +a. Only Posix-mode shells should exit on an assignment failure in the + temporary environment preceding a special builtin. This is how it's been + documented. + +b. Fixed a bug that caused a failed special builtin to not exit a posix-mode + shell if the failing builtin was on the LHS of a && or ||. + +c. Changed the handling of unquoted backslashes in regular expressions to be + closer to bash-4.2. + +d. globstar (**) no longer traverses symbolic links that resolve to + directories. This eliminates some duplicate entries. + +e. Fixed a bug that caused a SIGCHLD trap handler to not be able to change the + SIGCHLD disposition. + +f. Fixed a bug that caused a crash when -x was enabled and a command + contained a printable multibyte (wide) character. + +g. Fixed a bug that caused an interactive shell without line editing enabled + to read invalid data after receiving a SIGINT. + +h. Fixed a bug that caused command word completion to fail if the directory in + $PATH where the completion would be found contained single or double quotes. + +i. Fixed a bug that caused a shell with -v enabled to print commands in $() + multiple times. + +2. Changes to Readline + +a. Fixed a bug that caused `undo' to reference freed memory or null pointers. + +3. New Features in Bash + +a. The [[ -v ]] option now understands array references (foo[1]) and returns + success if the referenced element has a value. + +------------------------------------------------------------------------------ +This document details the changes between this version, bash-4.3-rc2, and the +previous version, bash-4.3-rc1. + +1. Changes to Bash + +a. Fixed a bug that left variables set by printf -v marked as invisible. + +b. Fixed an off-by-one error in a job control warning message. + +c. Fixed a bug that caused the shell to crash after declaring a nameref variable + without a value. + +d. Fixed a bug that caused asynchronous commands to not set $? correctly. + +e. Fixed a bug that caused out-of-order execution when executing aliases with + embedded newlines containing `.' commands. + +f. Fixed a bug that caused error messages generated by expansion errors in + `for' commands to have the wrong line number. + +g. Fixed a bug that caused the `wait' builtin to not be interruptible in an + interactive shell with job control enabled. + +h. Fixed a bug that caused SIGINT and SIGQUIT to not be trappable in + asynchronous subshell commands. + +i. Bash now requires that the value assigned to a nameref variable be a valid + shell identifier (variable name or array reference). + +j. Converting an existing variable to a nameref variable now turns off the + -i/-l/-u/-c attributes. + +k. Displaying a nameref variable with `declare -p' now displays the nameref + variable and its value rather than following the nameref chain. + +l. Fixed a problem with interrupt handling that caused a second and subsequent + SIGINT to be ignored by interactive shells. + +m. Fixed a bug that caused certain positional parameter and array expansions + to mishandle (discard) null positional parameters and array elements. + +n. The shell no longer blocks receipt of signals while running trap handlers + for those signals, and allows most trap handlers to be run recursively + (running trap handlers while a trap handler is executing). + +o. The shell now handles backslashes in regular expression arguments to the + [[ command's =~ operator slightly differently, resulting in more + consistent behavior. + +2. Changes to Readline + +a. Fixed a bug that could cause readline to crash and seg fault attempting to + expand an empty history entry. + +b. Fixed a bug that caused a bad entry in the $LS_COLORS variable to abort all + color processing but leave color enabled. + +c. Fixed a bug that caused display problems with multi-line prompts containing + invisible characters on multiple lines. + +d. Fixed a bug that caused effects made by undoing changes to a history line to + be discarded. + +3. New Features in Bash + +4. New Features in Readline + +a. When creating shared libraries on Mac OS X, the pathname written into the + library (install_name) no longer includes the minor version number. +------------------------------------------------------------------------------ +This document details the changes between this version, bash-4.3-rc1, and the +previous version, bash-4.3-beta2. + +1. Changes to Bash + +a. Fixed a bug in bash completion that caused a tilde to be expanded even if + the `direxpand' option was not enabled. + +b. Fixed a potential bug that could cause corrupted input in interactive shells + running without line editing and with `ignoreeof' enabled. + +c. Fixed a bug that could cause failures when opening pipes back to shells + created to run process substitutions. + +d. Fixed a bug that caused an assignment to TEXTDOMAIN to require TEXTDOMAINDIR + to be set in order to actually change the current text domain. + +e. Changed the way redirections are printed to avoid confusion when the target + of an output redirection is a process substitution beginning with `>'. + +2. Changes to Readline + +a. Shared library building is now supported on Mac OS X 10.9 (Darwin 13). + +3. New Features in Bash + +a. `cd' has a new `-@' option to browse a file's extended attributes on + systems that support O_XATTR. + +4. New Features in Readline + +a. There are additional default key bindings for MinGW32 + +------------------------------------------------------------------------------ +This document details the changes between this version, bash-4.3-beta2, and the +previous version, bash-4.3-beta. + +1. Changes to Bash + +a. Fixed a bug that caused assignment to an unset variable using a negative + subscript to result in a segmentation fault. + +b. Fixed a bug that caused assignment to a string variable using a negative + subscript to use the incorrect index. + +c. Fixed a bug that caused some strings to be interpreted as invalid + extended globbing expressions when used with the help builtin. + +d. Fixed a bug that caused an attempt to trap a signal whose disposition + cannot be changed to reference uninitialized memory. + +e. Command completion now skips assignment statements preceding a command + name and completes the command. + +f. Fixed a bug that caused `compgen -f' in a non-interactive shell to dump + core under certain circumstances. + +g. Fixed a bug that caused the `read -N' to misbehave when the input stream + contains 0xff. + +2. Changes to Readline + +a. Changed message when an incremental search fails to include "failed" in + the prompt and display the entire search string instead of just the last + matching portion. + +b. Fixed a bug that caused an arrow key typed to an incremental search prompt + to process the key sequence incorrectly. + +c. Additional key bindings for arrow keys on MinGW. + +3. New Features in Bash + +a. The help builtin now attempts substring matching (as it did through + bash-4.2) if exact string matching fails. + +b. The fc builtin now interprets -0 as the current command line. + +c. Completing directory names containing shell variables now adds a trailing + slash if the expanded result is a directory. + +4. New Features in Readline + +a. rl_change_environment: new application-settable variable that controls + whether or not Readline modifies the environment (currently readline + modifies only LINES and COLUMNS). + +------------------------------------------------------------------------------ +This document details the changes between this version, bash-4.3-beta, and the +previous version, bash-4.3-alpha. + +1. Changes to Bash + +a. Fixed a bug in the prompt directory name "trimming" code that caused + memory corruption and garbled the results. + +b. Fixed a bug that caused single quotes that resulted from $'...' quoting + in the replacement portion of a double-quoted ${word/pat/rep} expansion + to be treated as quote characters. + +c. Fixed a bug that caused assignment statements preceding a command word to + result in assignment statements following a declaration command to not be + expanded like assignment statements. + +d. Fixed a bug with variable search order in the presence of local variables + with the same name as variables in the temporary environment supplied to + a shell function. + +e. Fixed a bug that caused constructs like 1<(2) to be interpreted as process + substitutions even in an arithmetic context. + +f. Fixed several cases where `invisible' variables (variables with attributes + but no values, which are technically unset) were treated incorrectly. + +g. Fixed a bug that caused group commands in pipelines that were not the + last element to not run the EXIT trap. + +h. Fixed a bug that caused `unset -n' to not unset a nameref variable in + certain cases. + +i. Fixed the nameref circular reference checking to be less strict and only + disallow a nameref variable with the same value as its name at the global + scope. + +j. Fixed a bug that caused trap handlers to be executed recursively, + corrupting internal data structures. + +k. Fixed a bug that could result in bash not compiling if certain options were + not enabled. + +l. Fixed a bug that caused the arithmetic expansion code to attempt variable + assignments when operator precedence prohibited them. + +m. Word expansions like ${foo##bar} now understand indirect variable references. + +n. Fixed a bug that caused `declare -fp name' to not display a function + definition. + +o. Fixed a bug that caused asynchronous child processes to modify the stdin + file pointer when bash was using it to read a script, which modified the + parent's value as well. + +2. Changes to Readline + +a. Fixed a bug in vi mode that caused the arrow keys to set the saved last + vi-mode command to the wrong value. + +b. Fixed a bug that caused double-quoted strings to be scanned incorrectly + when being used as the value of a readline variable assignment. + +c. Fixed a bug with vi mode that prevented `.' from repeating a command + entered on a previous line (command). + +d. Fixed a bug that could cause completion to core dump if it was interrupted + by a signal. + +e. Readline now sends the meta-key enable string to the terminal if the + terminal has been successfully initialized. + +f. Readline now calls the signal hook after resizing the terminal when it + receives a SIGWINCH. + +g. Fixed a bug that could cause the history list code to perform an out-of- + bounds array reference if the history list is empty. + +3. New Features in Bash + +a. Shells started to run process substitutions now run any trap set on EXIT. + +b. There is now a configure-time option to enable the globasciiranges option + by default. + +c. The read builtin now checks its first variable argument for validity before + trying to read any input. + +------------------------------------------------------------------------------ +This document details the changes between this version, bash-4.3-alpha, +and the previous version, bash-4.2-release. + +1. Changes to Bash + +a. Fixed several bugs concerning incomplete bracket expressions in filename + generation (globbing) patterns. + +b. Fixed a bug with single quotes and WORD in ${param op WORD} when running + in Posix mode. + +c. Fixed a bug that caused the pattern removal and pattern substitution word + expansions and case statement word expansion to not match the empty string. + +d. Fixed a bug that caused the tzset() function to not work after changing + the TZ enviroment variable. + +e. Fixed a bug that caused the RHS of an assignment statement to undergo + word splitting when it contained an unquoted $@. + +f. Fixed bugs that caused the shell to not react to a SIGINT sent while + waiting for a child process to exit. + +g. Bash doesn't try to run things in a signal handler context when it gets a + signal (SIGINT/SIGHUP/etc) while reading input using readline but still + be responsive to terminating signals. + +h. Fixed a bug that caused bash to go into an infinite loop if a filename + to be matched contained an invalid multibyte character. + +i. Fixed a bug that caused PS4 to end up being truncated if it is longer + than 128 bytes. + +j. Fixed a bug that caused brace expansion to not skip over double-quoted + command substitution. + +k. System-specific updates for: DJGPP, HP/UX, Mac OS X + +l. Fixed a bug in displaying commands that caused redirections to be associated + with the wrong part of the command. + +m. Fixed the coproc cleanup to unset the appropriate shell variables when a + coproc terminates. + +n. Fixed a bug that caused `fc' to dump core due to incorrect calculation of + the last history entry. + +o. Added workarounds for FreeBSD's implementation of faccessat/eaccess and + `test -x'. + +p. Fixed a bug that caused the shell to not match patterns containing + control-A. + +q. Fixed a bug that could result in doubled error messages when the `printf' + builtin got a write error. + +r. Fixed a bug that caused the shell to not correctly expand words containing + multiple consecutive quoted empty strings (""""""aa). + +s. Fixed a bug that caused the shell to not correctly parse multi-line + process substitutions containing comments and quoted strings. + +t. Fixed a problem with the bash malloc's internal idea of the top of the + memory heap that resulted in incorrect decisions to try to reduce the + break and give memory back to the kernel. + +u. There are changes to the expansions peformed on compound array assignments, + in an effort to make foo=( [ind1]=bar [ind2]=baz ) identical to + foo[ind1]=bar foo[ind2]=baz. + +v. Bash now reports an error if `read -a name' is used when `name' is an + existing associative array. + +w. Fixed a bug that allowed an attempted assignment to a readonly variable + in an arithmetic expression to not return failure. + +x. Fixed several bugs that caused completion functions to be invoked even when + the cursor was before the first word in the command. + +y. Fixed a bug that caused parsing a command substitution to overwrite the + parsing state associated with the complete input line. + +z. Fixed several bugs with the built-in snprintf replacement and field widths + and floating point. + +aa. Fixed a bug that caused incorrect offset calculations and input buffer + corruption when reading files longer than 2^31 bytes. + +bb. Fixed several bugs where bash performed arithmetic evaluation in contexts + where evaluation is suppressed. + +cc. Fixed a bug that caused bash to close FIFOs used for process substitution + too early when a shell function was executing, but protect against using + all file descriptors when the shell functions are invoked inside loops. + +dd. Added checks for printable (and non-printable) multibyte characters for + use in error messages. + +ee. Fixed a bug that caused ^O (operate-and-get-next) to not work correctly + at the end of the history list. + +ff. Fixed a bug that caused command-oriented history to incorrectly combine + here documents into one line. + +gg. Fixed a bug that caused importing SHELLOPTS from the environment into a + Posix-mode shell to print an error message and refuse to parse it. + +hh. Fixed a bug that caused the shell to delete an extra history entry when + using `history -s'. + +ii. Fixed a bug that caused floating-point exceptions and overflow errors + for the / and % arithmetic operators when using INTMAX_MIN and -1. + +jj. Fixed a bug that caused parsing errors when reading an arithmetic for + loop inside a command substitution. + +kk. Fixed a bug that caused a readonly function to be unset when unset was + called without the -f or -v option. + +ll. Fixed several bugs in the code that quotes characters special to regular + expressions when used in a quoted string on the RHS of the =~ operator + to the [[ command. + +mm. Fixed a bug that caused redirections to fail because the file descriptor + limit was set to a value less than 10. + +nn. Fixed a bug that caused the `read' builtin to execute code in a signal + handler context if read timed out. + +oo. Fixed a bug that caused extended globbing patterns to not match files + beginning with `.' correctly when a `.' was explicitly supplied in the + pattern. + +pp. Fixed a bug that caused key sequences longer than two characters to not + work when used with `bind -x'. + +qq. Fixed a bug that resulted in redefined functions having the wrong source + file names in BASH_SOURCE. + +rr. Fixed a bug that caused the read builtin to assign null strings to variables + when using `read -N', which caused core dumps when referenced + +ss. Fixed a bug that caused `bash -m script' to not enable job control while + running the script. + +tt. Fixed a bug that caused `printf -v var' to dump core when used with the + %b format code. + +uu. Fixed a bug that caused the shell to exit with the wrong status if -e was + active and the shell exited on a substitution error. + +vv. Fixed a bug that caused the shell to seg fault if an array variable with + the same name as an existing associative array was implicitly created by + an assignment (declare a[n]=b). + +ww. Fixed a bug that caused a redirection to misbehave if the number specified + for a file descriptor overflows an intmax_t. + +xx. Fixed several bugs with the handling of valid and invalid unicode character + values when used with the \u and \U escape sequences to printf and $'...'. + +yy. Fixed a bug that caused tildes to not be escaped in expanded filenames, + making them subject to later expansion. + +zz. When using the pattern substitution word expansion, bash now runs the + replacement string through quote removal, since it allows quotes in that + string to act as escape characters. This is not backwards compatible, so + it can be disabled by setting the bash compatibility mode to 4.2. + +aaa. Fixed the rest of the cases where the shell runs non-allowed code in a + signal handler context. + +bbb. Fixed a bug that caused spurious DEL characters (\177) to appear in + double-quoted expansion where the RHS is evaluated to the empty string. + +ccc. Fixed a bug that caused the use of the shell's internal random number + generator for temporary file names to perturb the random number + sequence. + +ddd. Fixed several bugs that caused `declare -g' to not set the right global + variables or to misbehave when declaring global indexed arrays. + +eee. Fixed a logic bug that caused extended globbing in a multibyte locale to + cause failures when using the pattern substititution word expansions. + +fff. Fixed a bug that caused the `lastpipe' option to corrupt the file + descriptor used to read the script. + +ggg. Fixed a bug that causes the shell to delete DEL characters in the + expanded value of variables used in the same quoted string as variables + that expand to nothing. + +hhh. Fixed a bug that caused the shell to assign the wrong value from an + assignment like (( x=7 )) when `x' was an existing array variable. + +iii. Fixed a bug that caused the shell to misbehave when generating sequences + and the boundary values overflow an intmax_t. + +jjj. Fixed a bug caused expansion errors if an expansion of "$@" appeared + next to another expansion (e.g.. "${@}${x}"). + +kkk. Fixed a potential buffer overflow bug when performing /dev/fd expansion. + +lll. Fixed a bug that resulted in an extra semicolon being added to compound + assignments when they were added to the history list. + +mmm. Fixed a bug that caused mapfile to read one extra line from the input. + +nnn. Fixed a bug that caused the mail checking code to use uninitialized + values. + +ooo. Fixed a bug that prevented history timestamps from being saved if the + history comment character is unset. + +ppp. Fixed a bug that caused the case-modifying expansions to not work with + multibyte characters. + +qqq. Fixed a bug that caused the edit-and-execute bindable readline command + to see the wrong data if invoked in the middle of a multi-line quoted + string. + +rrr. Fixed a bug that resulted in the shell returning the wrong exit status + for a background command on systems that recycle PIDs very quickly. + +sss. Fixed a bug that caused asynchronous group commands to not run any EXIT + trap defined in the body of the command. + +ttt. Fixed a bug that caused `eval "... ; return"' to not clean up properly. + +uuu. Fixed a bug that caused the shell to dump core if `read' reads an escaped + IFS whitespace character. + +vvv. Fixed a bug that caused BASH_COMMAND to be set to an incorrect value when + executing a (...) subshell. + +www. Fixed a couple of pointer aliasing bugs with the token string in arithmetic + evaluation. + +xxx. Fixed a bug with parsing multi-line command substitutions when reading + the `do' keyword followed by whitespace. + +yyy. Fixed a bug that caused the shell to seg fault if the time given to the + printf %(...)T format overflowed the value accepted by localtime(3). + +zzz. Fixed a problem with displaying help topics in two columns when the + translated text contained multibyte characters. + +aaaa. Fixed a bug with the extended globbing pattern matcher where a `*' was + followed by a negated extended glob pattern. + +bbbb. Fixed a race condition with short-lived coproc creation and reaping that + caused the child process to be reaped before the various coproc shell + variables were initialized. + +cccc. Fixed a bug where turning off `errexit' in command substitution subshells + was not reflected in $SHELLOPTS. + +dddd. Partially fixed an inconsistency in how the shell treated shell + functions run from an EXIT trap. + +eeee. Fixed a bug in how the shell invalidated FIFOs used for process + substitution when executing a pipeline (once rather than in every child). + +ffff. Fixed a bug that occurred when expanding a special variable ($@, $*) + within double quotes and the expansion resulted in an empty string. + +gggg. Fixed bugs with executing a SIGCHLD trap handler to make sure that it's + executed once per exited child. + +hhhh. Fixed a bug that caused `declare' and `test' to find variables that + had been given attributes but not assigned values. Such variables are + not set. + +iiii. Fixed a bug that caused commands in process substitutions to not look in + the local temporary environment when performing word expansions. + +jjjj. Fixed several problems with globstar expansions (**/**) returning null + filenames and multiple instances of the same pathname. + +kkkk. Fixed an oversight that did not allow the exit status of `coproc' to + be inverted using `!'. + +llll. Fixed a bug that caused the -e option to be re-enabled using `set -e' + even when executing in a context where -e is ignored. + +mmmm. Fixed a (mostly theoretical) bug with input lines longer than SIZE_MAX. + +nnnn. Fixed a bug that could result in double evaluation of command + substitutions when they appear in failed redirections. + +oooo. Fixed a bug that could cause seg faults during `mapfile' callbacks if + the callback unsets the array variable mapfile is using. + +pppp. Fixed several problems with variable assignments using ${var:=value} + when the variable assignment is supposed to have side effects. + +qqqq. Fixed a bug that caused a failure of an assignment statement preceding a + builtin caused the next invocation of a special builtin to exit the shell. + +rrrr. Fixed several problems with IFS when it appears in the temporary environment + and is used in redirections. + +ssss. Fixed a problem that caused IFS changes using ${IFS:=value} to modify + how preceding expansions were split. + +tttt. Fixed a problem that caused subshells to not run an EXIT trap they set. + +uuuu. Fixed a problem that caused shells started in posix mode to attempt to + import shell functions with invalid names from the environment. We now + print a warning. + +vvvv. Worked around a kernel problem that caused SIGCHLD to interrupt open(2) + on a FIFO used for process substitution, even if the SIGCHLD handler was + installed with the SA_RESTART flag. + +wwww. Fixed a problem that resulted in inconsistent expansion of $* and ${a[*]}. + +xxxx. Fixed a problem that caused `read -t' to crash when interrupted by + SIGINT. + +yyyy. Fixed a problem that caused pattern removal to fail randomly because the + pattern matcher read beyond the end of a string. + +zzzz. Fixed a bug that caused core dumps when shell functions tried to create + local shadow copies of special variables like GROUPS. + +aaaaa. Fixed a bug that caused SIGTERM to be occasionally lost by children of + interactive shells when it arrived before the child process reset the + handler from SIG_DFL. + +bbbbb. Fixed a bug that caused redirections like <&n- to leave file descriptor + n closed if executed with a builtin command. + +ccccc. Fixed a bug that caused incorrect completion quoting when completing a + word containing a globbing character with `show-all-if-ambiguous' set. + +ddddd. Fixed a bug that caused printf's %q format specifier not to quote a + tilde even if it appeared in a location where it would be subject to + tilde expansion. + +2. Changes to Readline + +a. Fixed a bug that did not allow the `dd', `cc', or `yy' vi editing mode + commands to work on the entire line. + +b. Fixed a bug that caused redisplay problems with prompts longer than 128 + characters and history searches. + +c. Fixed a bug that caused readline to try and run code to modify its idea + of the screen size in a signal handler context upon receiving a SIGWINCH. + +d. Fixed a bug that caused the `meta' key to be enabled beyond the duration + of an individual call top readline(). + +e. Added a workaround for a wcwidth bug in Mac OS X that caused readline's + redisplay to mishandle zero-width combining characters. + +f. Fixed a bug that caused readline to `forget' part of a key sequence when + a multiple-key sequence caused it to break out of an incremental search. + +g. Fixed bugs that caused readline to execute code in a signal handler + context if interrupted while reading from the file system during completion. + +h. Fixed a bug that caused readline to `forget' part of a key sequence when + reading an unbound multi-character key sequence. + +i. Fixed a bug that caused Readline's signal handlers to be installed beyond + the bounds of a single call to readline(). + +j. Fixed a bug that caused the `.' command to not redo the most recent `R' + command in vi mode. + +k. Fixed a bug that caused ignoring case in completion matches to result in + readline using the wrong match. + +l. Paren matching now works in vi insert mode. + +m. Fix menu-completion to make show-all-if-ambiguous and menu-complete-display-prefix + work together. + +n. Fixed a bug that didn't allow the `cc', `dd', or `yy' commands to be redone + in vi editing mode. + +o. Fixed a bug that caused the filename comparison code to not compare + multibyte characters correctly when using case-sensitive or case-mapping + comparisons. + +p. Fixed the input reading loop to call the input hook function only when there + is no terminal input available. + +q. Fixed a bug that caused binding a macro to a multi-character key sequence + where the sequence and macro value share a common prefix to not perform + the macro replacement. + +r. Fixed several redisplay errors with multibyte characters and prompts + containing invisible characters when using horizontal scrolling. + +s. Fixed a bug that caused redisplay errors when trying to overwrite + existing characters using multibyte characters. + +3. 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, so `help read' + does not match `readonly'. + +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. + +4. 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 needs to check whether there is data available on its + input source. The default hook checks rl_instream. + +l. Readline calls an application-set event hook (rl_signal_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. Not currently called for SIGHUP or SIGTERM. + +m. If the user-settable variable `history-size' is set to a value less than + 0, the history list size is unlimited. + +------------------------------------------------------------------------------ This document details the changes between this version, bash-4.2-release, and the previous version, bash-4.2-rc2. |