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@@ -0,0 +1,2403 @@ +This is a terse description of the new features added to bash-5.1 since +the release of bash-5.0. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. `bind -x' now supports different bindings for different editing modes and + keymaps. + +b. Bash attempts to optimize the number of times it forks when executing + commands in subshells and from `bash -c'. + +c. Here documents and here strings now use pipes for the expanded document if + it's smaller than the pipe buffer size, reverting to temporary files if it's + larger. + +d. There are new loadable builtins: mktemp, accept, mkfifo, csv, cut/lcut + +e. In posix mode, `trap -p' now displays signals whose disposition is SIG_DFL + and those that were SIG_IGN when the shell starts. + +f. The shell now expands the history number (e.g., in PS1) even if it is not + currently saving commands to the history list. + +g. `read -e' may now be used with arbitrary file descriptors (`read -u N'). + +h. The `select' builtin now runs traps if its internal call to the read builtin + is interrupted by a signal. + +i. SRANDOM: a new variable that expands to a 32-bit random number that is not + produced by an LCRNG, and uses getrandom/getentropy, falling back to + /dev/urandom or arc4random if available. There is a fallback generator if + none of these are available. + +j. shell-transpose-words: a new bindable readline command that uses the same + definition of word as shell-forward-word, etc. + +k. The shell now adds default bindings for shell-forward-word, + shell-backward-word, shell-transpose-words, and shell-kill-word. + +l. Bash now allows ARGV0 appearing in the initial shell environment to set $0. + +m. If `unset' is executed without option arguments, bash tries to unset a shell + function if a name argument cannot be a shell variable name because it's not + an identifier. + +n. The `test -N' operator uses nanosecond timestamp granularity if it's + available. + +o. Bash posix mode now treats assignment statements preceding shell function + definitions the same as in its default mode, since POSIX has changed and + no longer requires those assignments to persist after the function returns + (POSIX interp 654). + +p. BASH_REMATCH is no longer readonly. + +q. wait: has a new -p VARNAME option, which stores the PID returned by `wait -n' + or `wait' without arguments. + +r. Sorting the results of pathname expansion now uses byte-by-byte comparisons + if two strings collate equally to impose a total order; the result of a + POSIX interpretation. + +s. Bash now allows SIGINT trap handlers to execute recursively. + +t. Bash now saves and restores state around setting and unsetting posix mode, + instead of having unsetting posix mode set a known state. + +u. Process substitution is now available in posix mode. + +v. READLINE_MARK: a new variable available while executing commands bound with + `bind -x', contains the value of the mark. + +w. Bash removes SIGCHLD from the set of blocked signals if it's blocked at shell + startup. + +x. `test -v N' can now test whether or not positional parameter N is set. + +y. `local' now honors the `-p' option to display all local variables at the + current context. + +z. The `@a' variable transformation now prints attributes for unset array + variables. + +aa. The `@A' variable transformation now prints a declare command that sets a + variable's attributes if the variable has attributes but is unset. + +bb. `declare' and `local' now have a -I option that inherits attributes and + value from a variable with the same name at a previous scope. + +cc. When run from a -c command, `jobs' now reports the status of completed jobs. + +dd. New `U', `u', and `L' parameter transformations to convert to uppercase, + convert first character to uppercase, and convert to lowercase, + respectively. + +ee. PROMPT_COMMAND: can now be an array variable, each element of which can + contain a command to be executed like a string PROMPT_COMMAND variable. + +ff. `ulimit' has a -R option to report and set the RLIMIT_RTTIME resource. + +gg. Associative arrays may be assigned using a list of key-value pairs within + a compound assignment. Compound assignments where the words are not of + the form [key]=value are assumed to be key-value assignments. A missing or + empty key is an error; a missing value is treated as NULL. Assignments may + not mix the two forms. + +hh. New `K' parameter transformation to display associative arrays as key- + value pairs. + +ii. Writing history to syslog now handles messages longer than the syslog max + length by writing multiple messages with a sequence number. + +jj. SECONDS and RANDOM may now be assigned using arithmetic expressions, since + they are nominally integer variables. LINENO is not an integer variable. + +kk. Bash temporarily suppresses the verbose option when running the DEBUG trap + while running a command from the `fc' builtin. + +ll. `wait -n' now accepts a list of job specifications as arguments and will + wait for the first one in the list to change state. + +mm. The associative array implementation can now dynamically increase the + size of the hash table based on insertion patterns. + +nn. HISTFILE is now readonly in a restricted shell. + +oo. The bash malloc now returns memory that is 16-byte aligned on 64-bit + systems. + +pp. If the hash builtin is listing hashed filenames portably, don't print + anything if the table is empty. + +qq. GLOBIGNORE now ignores `.' and `..' as a terminal pathname component. + +rr. Bash attempts to optimize away forks in the last command in a function body + under appropriate circumstances. + +ss. The globbing code now uses fnmatch(3) to check collation elements (if + available) even in cases without multibyte characters. + +tt. The `fg' and `bg' builtins now return an error in a command substitution + when asked to restart a job inherited from the parent shell. + +uu. The shell now attempts to unlink all FIFOs on exit, whether a consuming + process has finished with them or not. + +vv. There is a new contributed loadable builtin: asort. + +2. New Features in Readline + +a. If a second consecutive completion attempt produces matches where the first + did not, treat it as a new completion attempt and insert a match as + appropriate. + +b. Bracketed paste mode works in more places: incremental search strings, vi + overstrike mode, character search, and reading numeric arguments. + +c. Readline automatically switches to horizontal scrolling if the terminal has + only one line. + +d. Unbinding all key sequences bound to a particular readline function now + descends into keymaps for multi-key sequences. + +e. rl-clear-display: new bindable command that clears the screen and, if + possible, the scrollback buffer (bound to emacs mode M-C-l by default). + +f. New active mark and face feature: when enabled, it will highlight the text + inserted by a bracketed paste (the `active region') and the text found by + incremental and non-incremental history searches. This is tied to bracketed + paste and can be disabled by turning off bracketed paste. + +g. Readline sets the mark in several additional commands. + +h. Bracketed paste mode is enabled by default. + +i. Readline tries to take advantage of the more regular structure of UTF-8 + characters to identify the beginning and end of characters when moving + through the line buffer. + +j. The bindable operate-and-get-next command (and its default bindings) are + now part of readline instead of a bash-specific addition. + +k. The signal cleanup code now blocks SIGINT while processing after a SIGINT. + +------------------------------------------------------------------------------- +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 signifies 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 mechanism 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). + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-4.2 since +the release of bash-4.1. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +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 is a terse description of the new features added to bash-4.1 since +the release of bash-4.0. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. 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 if the compatibility level + is greater than 40. + +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. + +v. The mapfile/readarray builtin no longer stores the commands it invokes via + callbacks in the history list. + +w. There is a new `compat40' shopt option. + +2. 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. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-4.0 since +the release of bash-3.2. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +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 is a terse description of the new features added to bash-3.2 since +the release of bash-3.1. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. 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. + +2. 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 + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-3.0 since +the release of bash-2.05b. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. ANSI string expansion now implements the \x{hexdigits} escape. + +b. There is a new loadable `strftime' builtin. + +c. New variable, COMP_WORDBREAKS, which controls the readline completer's + idea of word break characters. + +d. The `type' builtin no longer reports on aliases unless alias expansion + will actually be performed. + +e. HISTCONTROL is now a colon-separated list of values, which permits + more extensibility and backwards compatibility. + +f. HISTCONTROL may now include the `erasedups' option, which causes all lines + matching a line being added to be removed from the history list. + +g. `configure' has a new `--enable-multibyte' argument that permits multibyte + character support to be disabled even on systems that support it. + +h. New variables to support the bash debugger: BASH_ARGC, BASH_ARGV, + BASH_SOURCE, BASH_LINENO, BASH_SUBSHELL, BASH_EXECUTION_STRING, + BASH_COMMAND + +i. FUNCNAME has been changed to support the debugger: it's now an array + variable. + +j. for, case, select, arithmetic commands now keep line number information + for the debugger. + +k. There is a new `RETURN' trap executed when a function or sourced script + returns (not inherited child processes; inherited by command substitution + if function tracing is enabled and the debugger is active). + +l. New invocation option: --debugger. Enables debugging and turns on new + `extdebug' shell option. + +m. New `functrace' and `errtrace' options to `set -o' cause DEBUG and ERR + traps, respectively, to be inherited by shell functions. Equivalent to + `set -T' and `set -E' respectively. The `functrace' option also controls + whether or not the DEBUG trap is inherited by sourced scripts. + +n. The DEBUG trap is run before binding the variable and running the action + list in a `for' command, binding the selection variable and running the + query in a `select' command, and before attempting a match in a `case' + command. + +o. New `--enable-debugger' option to `configure' to compile in the debugger + support code. + +p. `declare -F' now prints out extra line number and source file information + if the `extdebug' option is set. + +q. If `extdebug' is enabled, a non-zero return value from a DEBUG trap causes + the next command to be skipped, and a return value of 2 while in a + function or sourced script forces a `return'. + +r. New `caller' builtin to provide a call stack for the bash debugger. + +s. The DEBUG trap is run just before the first command in a function body is + executed, for the debugger. + +t. `for', `select', and `case' command heads are printed when `set -x' is + enabled. + +u. There is a new {x..y} brace expansion, which is shorthand for {x.x+1, + x+2,...,y}. x and y can be integers or single characters; the sequence + may ascend or descend; the increment is always 1. + +v. New ksh93-like ${!array[@]} expansion, expands to all the keys (indices) + of array. + +w. New `force_fignore' shopt option; if enabled, suffixes specified by + FIGNORE cause words to be ignored when performing word completion even + if they're the only possibilities. + +x. New `gnu_errfmt' shopt option; if enabled, error messages follow the `gnu + style' (filename:lineno:message) format. + +y. New `-o bashdefault' option to complete and compgen; if set, causes the + whole set of bash completions to be performed if the compspec doesn't + result in a match. + +z. New `-o plusdirs' option to complete and compgen; if set, causes directory + name completion to be performed and the results added to the rest of the + possible completions. + +aa. `kill' is available as a builtin even when the shell is built without + job control. + +bb. New HISTTIMEFORMAT variable; value is a format string to pass to + strftime(3). If set and not null, the `history' builtin prints out + timestamp information according to the specified format when displaying + history entries. If set, bash tells the history library to write out + timestamp information when the history file is written. + +cc. The [[ ... ]] command has a new binary `=~' operator that performs + extended regular expression (egrep-like) matching. + +dd. `configure' has a new `--enable-cond-regexp' option (enabled by default) + to enable the =~ operator and regexp matching in [[ ... ]]. + +ee. Subexpressions matched by the =~ operator are placed in the new + BASH_REMATCH array variable. + +ff. New `failglob' option that causes an expansion error when pathname + expansion fails to produce a match. + +gg. New `set -o pipefail' option that causes a pipeline to return a failure + status if any of the processes in the pipeline fail, not just the last + one. + +hh. printf builtin understands two new escape sequences: \" and \?. + +ii. `echo -e' understands two new escape sequences: \" and \?. + +jj. The GNU `gettext' package and libintl have been integrated; the shell's + messages can be translated into different languages. + +kk. The `\W' prompt expansion now abbreviates $HOME as `~', like `\w'. + +ll. The error message printed when bash cannot open a shell script supplied + as argument 1 now includes the name of the shell, to better identify + the error as coming from bash. + +mm. The parameter pattern removal and substitution expansions are now much + faster and more efficient when using multibyte characters. + +nn. The `jobs', `kill', and `wait' builtins now accept job control notation + even if job control is not enabled. + +oo. The historical behavior of `trap' that allows a missing `action' argument + to cause each specified signal's handling to be reset to its default is + now only supported when `trap' is given a single non-option argument. + +2. New Features in Readline + +a. History expansion has a new `a' modifier equivalent to the `g' modifier + for compatibility with the BSD csh. + +b. History expansion has a new `G' modifier equivalent to the BSD csh `g' + modifier, which performs a substitution once per word. + +c. All non-incremental search operations may now undo the operation of + replacing the current line with the history line. + +d. The text inserted by an `a' command in vi mode can be reinserted with + `.'. + +e. New bindable variable, `show-all-if-unmodified'. If set, the readline + completer will list possible completions immediately if there is more + than one completion and partial completion cannot be performed. + +f. There is a new application-callable `free_history_entry()' function. + +g. History list entries now contain timestamp information; the history file + functions know how to read and write timestamp information associated + with each entry. + +h. Four new key binding functions have been added: + + rl_bind_key_if_unbound() + rl_bind_key_if_unbound_in_map() + rl_bind_keyseq_if_unbound() + rl_bind_keyseq_if_unbound_in_map() + +i. New application variable, rl_completion_quote_character, set to any + quote character readline finds before it calls the application completion + function. + +j. New application variable, rl_completion_suppress_quote, settable by an + application completion function. If set to non-zero, readline does not + attempt to append a closing quote to a completed word. + +k. New application variable, rl_completion_found_quote, set to a non-zero + value if readline determines that the word to be completed is quoted. + Set before readline calls any application completion function. + +l. New function hook, rl_completion_word_break_hook, called when readline + needs to break a line into words when completion is attempted. Allows + the word break characters to vary based on position in the line. + +m. New bindable command: unix-filename-rubout. Does the same thing as + unix-word-rubout, but adds `/' to the set of word delimiters. + +n. When listing completions, directories have a `/' appended if the + `mark-directories' option has been enabled. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.05b since +the release of bash-2.05a. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. If set, TMOUT is the default timeout for the `read' builtin. + +b. `type' has two new options: `-f' suppresses shell function lookup, and + `-P' forces a $PATH search. + +c. New code to handle multibyte characters. + +d. `select' was changed to be more ksh-compatible, in that the menu is + reprinted each time through the loop only if REPLY is set to NULL. + The previous behavior is available as a compile-time option. + +e. `complete -d' and `complete -o dirnames' now force a slash to be + appended to names which are symlinks to directories. + +f. There is now a bindable edit-and-execute-command readline command, + like the vi-mode `v' command, bound to C-xC-e in emacs mode. + +g. Added support for ksh93-like [:word:] character class in pattern matching. + +h. The $'...' quoting construct now expands \cX to Control-X. + +i. A new \D{...} prompt expansion; passes the `...' to strftime and inserts + the result into the expanded prompt. + +j. The shell now performs arithmetic in the largest integer size the + machine supports (intmax_t), instead of long. + +k. If a numeric argument is supplied to one of the bash globbing completion + functions, a `*' is appended to the word before expansion is attempted. + +l. The bash globbing completion functions now allow completions to be listed + with double tabs or if `show-all-if-ambiguous' is set. + +m. New `-o nospace' option for `complete' and `compgen' builtins; suppresses + readline's appending a space to the completed word. + +n. New `here-string' redirection operator: <<< word. + +o. When displaying variables, function attributes and definitions are shown + separately, allowing them to be re-used as input (attempting to re-use + the old output would result in syntax errors). + +p. There is a new configuration option `--enable-mem-scramble', controls + bash malloc behavior of writing garbage characters into memory at + allocation and free time. + +q. The `complete' and `compgen' builtins now have a new `-s/-A service' + option to complete on names from /etc/services. + +r. `read' has a new `-u fd' option to read from a specified file descriptor. + +s. Fix the completion code so that expansion errors in a directory name + don't cause a longjmp back to the command loop. + +t. Fixed word completion inside command substitution to work a little more + intuitively. + +u. The `printf' %q format specifier now uses $'...' quoting to print the + argument if it contains non-printing characters. + +v. The `declare' and `typeset' builtins have a new `-t' option. When applied + to functions, it causes the DEBUG trap to be inherited by the named + function. Currently has no effect on variables. + +w. The DEBUG trap is now run *before* simple commands, ((...)) commands, + [[...]] conditional commands, and for ((...)) loops. + +x. The expansion of $LINENO inside a shell function is only relative to the + function start if the shell is interactive -- if the shell is running a + script, $LINENO expands to the line number in the script. This is as + POSIX-2001 requires. + +y. The bash debugger in examples/bashdb has been modified to work with the + new DEBUG trap semantics, the command set has been made more gdb-like, + and the changes to $LINENO make debugging functions work better. Code + from Gary Vaughan. + +z. New [n]<&word- and [n]>&word- redirections from ksh93 -- move fds (dup + and close). + +aa. There is a new `-l' invocation option, equivalent to `--login'. + +bb. The `hash' builtin has a new `-l' option to list contents in a reusable + format, and a `-d' option to remove a name from the hash table. + +cc. There is now support for placing the long help text into separate files + installed into ${datadir}/bash. Not enabled by default; can be turned + on with `--enable-separate-helpfiles' option to configure. + +dd. All builtins that take operands accept a `--' pseudo-option, except + `echo'. + +ee. The `echo' builtin now accepts \0xxx (zero to three octal digits following + the `0') in addition to \xxx (one to three octal digits) for SUSv3/XPG6/ + POSIX.1-2001 compliance. + + +2. New Features in Readline + +a. Support for key `subsequences': allows, e.g., ESC and ESC-a to both + be bound to readline functions. Now the arrow keys may be used in vi + insert mode. + +b. When listing completions, and the number of lines displayed is more than + the screen length, readline uses an internal pager to display the results. + This is controlled by the `page-completions' variable (default on). + +c. New code to handle editing and displaying multibyte characters. + +d. The behavior introduced in bash-2.05a of deciding whether or not to + append a slash to a completed name that is a symlink to a directory has + been made optional, controlled by the `mark-symlinked-directories' + variable (default is the 2.05a behavior). + +e. The `insert-comment' command now acts as a toggle if given a numeric + argument: if the first characters on the line don't specify a + comment, insert one; if they do, delete the comment text + +f. New application-settable completion variable: + rl_completion_mark_symlink_dirs, allows an application's completion + function to temporarily override the user's preference for appending + slashes to names which are symlinks to directories. + +g. New function available to application completion functions: + rl_completion_mode, to tell how the completion function was invoked + and decide which argument to supply to rl_complete_internal (to list + completions, etc.). + +h. Readline now has an overwrite mode, toggled by the `overwrite-mode' + bindable command, which could be bound to `Insert'. + +i. New application-settable completion variable: + rl_completion_suppress_append, inhibits appending of + rl_completion_append_character to completed words. + +j. New key bindings when reading an incremental search string: ^W yanks + the currently-matched word out of the current line into the search + string; ^Y yanks the rest of the current line into the search string, + DEL or ^H deletes characters from the search string. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.05a since +the release of bash-2.05. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. Added support for DESTDIR installation root prefix, so you can do a + `make install DESTDIR=bash-root' and do easier binary packaging. + +b. Added support for builtin printf "'" flag character as per latest POSIX + drafts. + +c. Support for POSIX.2 printf(1) length specifiers `j', `t', and `z' (from + ISO C99). + +d. New autoconf macro, RL_LIB_READLINE_VERSION, for use by other applications + (bash doesn't use very much of what it returns). + +e. `set [-+]o nolog' is recognized as required by the latest POSIX drafts, + but ignored. + +f. New read-only `shopt' option: login_shell. Set to non-zero value if the + shell is a login shell. + +g. New `\A' prompt string escape sequence; expands to time in 24 HH:MM format. + +h. New `-A group/-g' option to complete and compgen; does group name + completion. + +i. New `-t' option to `hash' to list hash values for each filename argument. + +j. New [-+]O invocation option to set and unset `shopt' options at startup. + +k. configure's `--with-installed-readline' option now takes an optional + `=PATH' suffix to set the root of the tree where readline is installed + to PATH. + +l. The ksh-like `ERR' trap has been added. The `ERR' trap will be run + whenever the shell would have exited if the -e option were enabled. + It is not inherited by shell functions. + +m. `readonly', `export', and `declare' now print variables which have been + given attributes but not set by assigning a value as just a command and + a variable name (like `export foo') when listing, as the latest POSIX + drafts require. + +n. `bashbug' now requires that the subject be changed from the default. + +o. configure has a new `--enable-largefile' option, like other GNU utilities. + +p. `for' loops now allow empty word lists after `in', like the latest POSIX + drafts require. + +q. The builtin `ulimit' now takes two new non-numeric arguments: `hard', + meaning the current hard limit, and `soft', meaning the current soft + limit, in addition to `unlimited' + +r. `ulimit' now prints the option letter associated with a particular + resource when printing more than one limit. + +s. `ulimit' prints `hard' or `soft' when a value is not `unlimited' but is + one of RLIM_SAVED_MAX or RLIM_SAVED_CUR, respectively. + +t. The `printf' builtin now handles the %a and %A conversions if they're + implemented by printf(3). + +u. The `printf' builtin now handles the %F conversion (just about like %f). + +v. The `printf' builtin now handles the %n conversion like printf(3). The + corresponding argument is the name of a shell variable to which the + value is assigned. + +2. New Features in Readline + +a. Added extern declaration for rl_get_termcap to readline.h, making it a + public function (it was always there, just not in readline.h). + +b. New #defines in readline.h: RL_READLINE_VERSION, currently 0x0402, + RL_VERSION_MAJOR, currently 4, and RL_VERSION_MINOR, currently 2. + +c. New readline variable: rl_readline_version, mirrors RL_READLINE_VERSION. + +d. New bindable boolean readline variable: match-hidden-files. Controls + completion of files beginning with a `.' (on Unix). Enabled by default. + +e. The history expansion code now allows any character to terminate a + `:first-' modifier, like csh. + +f. New bindable variable `history-preserve-point'. If set, the history + code attempts to place the user at the same location on each history + line retrieved with previous-history or next-history. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.05 since +the release of bash-2.04. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. Added a new `--init-file' invocation argument as a synonym for `--rcfile', + per the new GNU coding standards. + +b. The /dev/tcp and /dev/udp redirections now accept service names as well as + port numbers. + +c. `complete' and `compgen' now take a `-o value' option, which controls some + of the aspects of that compspec. Valid values are: + + default - perform bash default completion if programmable + completion produces no matches + dirnames - perform directory name completion if programmable + completion produces no matches + filenames - tell readline that the compspec produces filenames, + so it can do things like append slashes to + directory names and suppress trailing spaces + +d. A new loadable builtin, realpath, which canonicalizes and expands symlinks + in pathname arguments. + +e. When `set' is called without options, it prints function definitions in a + way that allows them to be reused as input. This affects `declare' and + `declare -p' as well. This only happens when the shell is not in POSIX + mode, since POSIX.2 forbids this behavior. + +f. Bash-2.05 once again honors the current locale setting when processing + ranges within pattern matching bracket expressions (e.g., [A-Z]). + +2. New Features in Readline + +a. The blink timeout for paren matching is now settable by applications, + via the rl_set_paren_blink_timeout() function. + +b. _rl_executing_macro has been renamed to rl_executing_macro, which means + it's now part of the public interface. + +c. Readline has a new variable, rl_readline_state, which is a bitmap that + encapsulates the current state of the library; intended for use by + callbacks and hook functions. + +d. New application-callable function rl_set_prompt(const char *prompt): + expands its prompt string argument and sets rl_prompt to the result. + +e. New application-callable function rl_set_screen_size(int rows, int cols): + public method for applications to set readline's idea of the screen + dimensions. + +f. New function, rl_get_screen_size (int *rows, int *columns), returns + readline's idea of the screen dimensions. + +g. The timeout in rl_gather_tyi (readline keyboard input polling function) + is now settable via a function (rl_set_keyboard_input_timeout()). + +h. Renamed the max_input_history variable to history_max_entries; the old + variable is maintained for backwards compatibility. + +i. The list of characters that separate words for the history tokenizer is + now settable with a variable: history_word_delimiters. The default + value is as before. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.04 since +the release of bash-2.03. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. The history builtin has a `-d offset' option to delete the history entry + at position `offset'. + +b. The prompt expansion code has two new escape sequences: \j, the number of + active jobs; and \l, the basename of the shell's tty device name. + +c. The `bind' builtin has a new `-x' option to bind key sequences to shell + commands. + +d. There is a new shell option, no_empty_command_completion, which, when + enabled, disables command completion when TAB is typed on an empty line. + +e. The `help' builtin has a `-s' option to just print a builtin's usage + synopsis. + +f. There are several new arithmetic operators: id++, id-- (variable + post-increment/decrement), ++id, --id (variable pre-increment/decrement), + expr1 , expr2 (comma operator). + +g. There is a new ksh-93 style arithmetic for command: + for ((expr1 ; expr2; expr3 )); do list; done + +h. The `read' builtin has a number of new options: + -t timeout only wait timeout seconds for input + -n nchars only read nchars from input instead of a full line + -d delim read until delim rather than newline + -s don't echo input chars as they are read + +i. The redirection code now handles several filenames specially: + /dev/fd/N, /dev/stdin, /dev/stdout, and /dev/stderr, whether or + not they are present in the file system. + +j. The redirection code now recognizes pathnames of the form + /dev/tcp/host/port and /dev/udp/host/port, and tries to open a socket + of the appropriate type to the specified port on the specified host. + +k. The ksh-93 ${!prefix*} expansion, which expands to the names of all + shell variables with prefix PREFIX, has been implemented. + +l. There is a new dynamic variable, FUNCNAME, which expands to the name of + a currently-executing function. Assignments to FUNCNAME have no effect. + +m. The GROUPS variable is no longer readonly; assignments to it are silently + discarded. This means it can be unset. + +n. A new programmable completion facility, with two new builtin commands: + complete and compgen. + +o. configure has a new option, `--enable-progcomp', to compile in the + programmable completion features (enabled by default). + +p. `shopt' has a new option, `progcomp', to enable and disable programmable + completion at runtime. + +q. Unsetting HOSTFILE now clears the list of hostnames used for completion. + +r. configure has a new option, `--enable-bash-malloc', replacing the old + `--with-gnu-malloc' (which is still present for backwards compatibility). + +s. There is a new manual page describing rbash, the restricted shell. + +t. `bashbug' has new `--help' and `--version' options. + +u. `shopt' has a new `xpg_echo' option, which controls the behavior of + `echo' with respect to backslash-escaped characters at runtime. + +v. If NON_INTERACTIVE_LOGIN_SHELLS is defined, all login shells read the + startup files, even if they are not interactive. + +w. The LC_NUMERIC variable is now treated specially, and used to set the + LC_NUMERIC locale category for number formatting, e.g., when `printf' + displays floating-point numbers. + +2. New features in Readline + +a. Parentheses matching is now always compiled into readline, and enabled + or disabled when the value of the `blink-matching-paren' variable is + changed. + +b. MS-DOS systems now use ~/_inputrc as the last-ditch inputrc filename. + +c. MS-DOS systems now use ~/_history as the default history file. + +d. history-search-{forward,backward} now leave the point at the end of the + line when the string to search for is empty, like + {reverse,forward}-search-history. + +e. history-search-{forward,backward} now leave the last history line found + in the readline buffer if the second or subsequent search fails. + +f. New function for use by applications: rl_on_new_line_with_prompt, used + when an application displays the prompt itself before calling readline(). + +g. New variable for use by applications: rl_already_prompted. An application + that displays the prompt itself before calling readline() must set this to + a non-zero value. + +h. A new variable, rl_gnu_readline_p, always 1. The intent is that an + application can verify whether or not it is linked with the `real' + readline library or some substitute. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.03 since +the release of bash-2.02. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. New `shopt' option, `restricted_shell', indicating whether or not the + shell was started in restricted mode, for use in startup files. + +b. Filename generation is now performed on the words between ( and ) in + array assignments (which it probably should have done all along). + +c. OLDPWD is now auto-exported, as POSIX.2 seems to require. + +d. ENV and BASH_ENV are read-only variables in a restricted shell. + +e. A change was made to the startup file code so that any shell begun with + the `--login' option, even non-interactive shells, will source the login + shell startup files. + +2. New Features in Readline + +a. Many changes to the signal handling: + o Readline now catches SIGQUIT and cleans up the tty before returning; + o A new variable, rl_catch_signals, is available to application writers + to indicate to readline whether or not it should install its own + signal handlers for SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP, + SIGTTIN, and SIGTTOU; + o A new variable, rl_catch_sigwinch, is available to application + writers to indicate to readline whether or not it should install its + own signal handler for SIGWINCH, which will chain to the calling + applications's SIGWINCH handler, if one is installed; + o There is a new function, rl_free_line_state, for application signal + handlers to call to free up the state associated with the current + line after receiving a signal; + o There is a new function, rl_cleanup_after_signal, to clean up the + display and terminal state after receiving a signal; + o There is a new function, rl_reset_after_signal, to reinitialize the + terminal and display state after an application signal handler + returns and readline continues + +b. There is a new function, rl_resize_terminal, to reset readline's idea of + the screen size after a SIGWINCH. + +c. New public functions: rl_save_prompt and rl_restore_prompt. These were + previously private functions with a `_' prefix. + +d. New function hook: rl_pre_input_hook, called just before readline starts + reading input, after initialization. + +e. New function hook: rl_display_matches_hook, called when readline would + display the list of completion matches. The new function + rl_display_match_list is what readline uses internally, and is available + for use by application functions called via this hook. + +f. New bindable function, delete-char-or-list, like tcsh. + +g. A new variable, rl_erase_empty_line, which, if set by an application using + readline, will cause readline to erase, prompt and all, lines on which the + only thing typed was a newline. + +h. New bindable variable: `isearch-terminators'. + +i. New bindable function: `forward-backward-delete-char' (unbound by default). + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.02 since +the release of bash-2.01.1. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. A new version of malloc, based on the older GNU malloc, that has many + changes, is more page-based, is more conservative with memory usage, + and does not `orphan' large blocks when they are freed. + +b. A new version of gmalloc, based on the old GLIBC malloc, with many + changes and range checking included by default. + +c. A new implementation of fnmatch(3) that includes full POSIX.2 Basic + Regular Expression matching, including character classes, collating + symbols, equivalence classes, and support for case-insensitive pattern + matching. + +d. ksh-88 egrep-style extended pattern matching ([@+*?!](patlist)) has been + implemented, controlled by a new `shopt' option, `extglob'. + +e. There is a new ksh-like `[[' compound command, which implements + extended `test' functionality. + +f. There is a new `printf' builtin, implemented according to the POSIX.2 + specification. + +g. There is a new feature for command substitution: $(< filename) now expands + to the contents of `filename', with any trailing newlines removed + (equivalent to $(cat filename)). + +h. There are new tilde prefixes which expand to directories from the + directory stack. + +i. There is a new `**' arithmetic operator to do exponentiation. + +j. There are new configuration options to control how bash is linked: + `--enable-profiling', to allow bash to be profiled with gprof, and + `--enable-static-link', to allow bash to be linked statically. + +k. There is a new configuration option, `--enable-cond-command', which + controls whether or not the `[[' command is included. It is on by + default. + +l. There is a new configuration option, `--enable-extended-glob', which + controls whether or not the ksh extended globbing feature is included. + It is enabled by default. + +m. There is a new configuration #define in config.h.top that, when enabled, + will cause all login shells to source /etc/profile and one of the user- + specific login shell startup files, whether or not the shell is + interactive. + +n. There is a new invocation option, `--dump-po-strings', to dump + a shell script's translatable strings ($"...") in GNU `po' format. + +o. There is a new `shopt' option, `nocaseglob', to enable case-insensitive + pattern matching when globbing filenames and using the `case' construct. + +p. There is a new `shopt' option, `huponexit', which, when enabled, causes + the shell to send SIGHUP to all jobs when an interactive login shell + exits. + +q. `bind' has a new `-u' option, which takes a readline function name as an + argument and unbinds all key sequences bound to that function in a + specified keymap. + +r. `disown' now has `-a' and `-r' options, to limit operation to all jobs + and running jobs, respectively. + +s. The `shopt' `-p' option now causes output to be displayed in a reusable + format. + +t. `test' has a new `-N' option, which returns true if the filename argument + has been modified since it was last accessed. + +u. `umask' now has a `-p' option to print output in a reusable format. + +v. A new escape sequence, `\xNNN', has been added to the `echo -e' and $'...' + translation code. It expands to the character whose ascii code is NNN + in hexadecimal. + +w. The prompt string expansion code has a new `\r' escape sequence. + +x. The shell may now be cross-compiled for the CYGWIN32 environment on + a Unix machine. + +2. New Features in Readline + +a. There is now an option for `iterative' yank-last-arg handline, so a user + can keep entering `M-.', yanking the last argument of successive history + lines. + +b. New variable, `print-completions-horizontally', which causes completion + matches to be displayed across the screen (like `ls -x') rather than up + and down the screen (like `ls'). + +c. New variable, `completion-ignore-case', which causes filename completion + and matching to be performed case-insensitively. + +d. There is a new bindable command, `magic-space', which causes history + expansion to be performed on the current readline buffer and a space to + be inserted into the result. + +e. There is a new bindable command, `menu-complete', which enables tcsh-like + menu completion (successive executions of menu-complete insert a single + completion match, cycling through the list of possible completions). + +f. There is a new bindable command, `paste-from-clipboard', for use on Win32 + systems, to insert the text from the Win32 clipboard into the editing + buffer. + +g. The key sequence translation code now understands printf-style backslash + escape sequences, including \NNN octal escapes. These escape sequences + may be used in key sequence definitions or macro values. + +h. An `$include' inputrc file parser directive has been added. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.01 since +the release of bash-2.0. As always, the manual page (doc/bash.1) is the +place to look for complete descriptions. + +1. New Features in Bash + +a. There is a new builtin array variable: GROUPS, the set of groups to which + the user belongs. This is used by the test suite. + +2. New Features in Readline + +a. If a key sequence bound to `universal-argument' is read while reading a + numeric argument started with `universal-argument', it terminates the + argument but is otherwise ignored. This provides a way to insert multiple + instances of a digit string, and is how GNU emacs does it. + +------------------------------------------------------------------------------- +This is a terse description of the new features added to bash-2.0 since +the release of bash-1.14.7. As always, the manual page (doc/bash.1) is +the place to look for complete descriptions. + +1. New Features in Bash + +a. There is a new invocation option, -D, that dumps translatable strings + in a script. + +b. The `long' invocation options must now be prefixed with `--'. + +c. New long invocation options: --dump-strings, --help, --verbose + +d. The `nolineediting' invocation option was renamed to `noediting'. + +e. The `nobraceexpansion' and `quiet' long invocation options were removed. + +f. The `--help' and `--version' long options now work as the GNU coding + standards specify. + +g. If invoked as `sh', bash now enters posix mode after reading the + startup files, and reads and executes commands from the file named + by $ENV if interactive (as POSIX.2 specifies). A login shell invoked + as `sh' reads $ENV after /etc/profile and ~/.profile. + +h. There is a new reserved word, `time', for timing pipelines, builtin + commands, and shell functions. It uses the value of the TIMEFORMAT + variable as a format string describing how to print the timing + statistics. + +i. The $'...' quoting syntax expands ANSI-C escapes in ... and leaves the + result single-quoted. + +j. The $"..." quoting syntax performs locale-specific translation of ... + and leaves the result double-quoted. + +k. LINENO now works correctly in functions. + +l. New variables: DIRSTACK, PIPESTATUS, BASH_VERSINFO, HOSTNAME, SHELLOPTS, + MACHTYPE. The first three are array variables. + +m. The BASH_VERSION and BASH_VERSINFO variables now include the shell's + `release status' (alpha[N], beta[N], release). + +n. Some variables have been removed: MAIL_WARNING, notify, history_control, + command_oriented_history, glob_dot_filenames, allow_null_glob_expansion, + nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and + cdable_vars. Most of them are now implemented with the new `shopt' + builtin; others were already implemented by `set'. + +o. Bash now uses some new variables: LC_ALL, LC_MESSAGES, LC_CTYPE, + LC_COLLATE, LANG, GLOBIGNORE, HISTIGNORE. + +p. The shell now supports integer-indexed arrays of unlimited length, + with a new compound assignment syntax and changes to the appropriate + builtin commands (declare/typeset, read, readonly, etc.). The array + index may be an arithmetic expression. + +q. ${!var}: indirect variable expansion, equivalent to eval \${$var}. + +r. ${parameter:offset[:length]}: variable substring extraction. + +s. ${parameter/pattern[/[/]string]}: variable pattern substitution. + +t. The $[...] arithmetic expansion syntax is no longer supported, in + favor of $((...)). + +u. Aliases can now be expanded in shell scripts with a shell option + (shopt expand_aliases). + +v. History and history expansion can now be used in scripts with + set -o history and set -H. + +w. All builtins now return an exit status of 2 for incorrect usage. + +x. Interactive shells resend SIGHUP to all running or stopped children + if (and only if) they exit due to a SIGHUP. + +y. New prompting expansions: \a, \e, \H, \T, \@, \v, \V. + +z. Variable expansion in prompt strings is now controllable via a shell + option (shopt promptvars). + +aa. Bash now defaults to using command-oriented history. + +bb. The history file ($HISTFILE) is now truncated to $HISTFILESIZE after + being written. + +cc. The POSIX.2 conditional arithmetic evaluation syntax (expr ? expr : expr) + has been implemented. + +dd. Each builtin now accepts `--' to signify the end of the options, except + as documented (echo, etc.). + +ee. All builtins use -p to display values in a re-readable format where + appropriate, except as documented (echo, type, etc.). + +ff. The `alias' builtin has a new -p option. + +gg. Changes to the `bind' builtin: + o has new options: -psPSVr. + o the `-d' option was renamed to `-p' + o the `-v' option now dumps variables; the old `-v' is now `-P' + +hh. The `bye' synonym for `exit' was removed. + +ii. The -L and -P options to `cd' and `pwd' have been documented. + +jj. The `cd' builtin now does spelling correction on the directory name + by default. This is settable with a shell option (shopt cdspell). + +kk. The `declare' builtin has new options: -a, -F, -p. + +ll. The `dirs' builtin has new options: -c, -p, -v. + +mm. The new `disown' builtin removes jobs from the shell's jobs table + or inhibits the resending of SIGHUP when the shell receives a + SIGHUP. + +nn. The `echo' builtin has a new escape character: \e. + +oo. The `enable' builtin can now load new builtins dynamically from shared + objects on systems with the dlopen/dlsym interface. There are a number + of examples in the examples/loadables directory. There are also + new options: -d, -f, -s, -p. + +pp. The `-all' option to `enable' was removed in favor of `-a'. + +qq. The `exec' builtin has new options: -l, -c, -a. + +rr. The `hash' builtin has a new option: -p. + +ss. The `history' builtin has new options: -c, -p, -s. + +tt. The `jobs' builtin has new options: -r, -s. + +uu. The `kill' builtin has new options: -n signum, -l signame. + +vv. The `pushd' and `popd' builtins have a new option: -n. + +ww. The `read' builtin has new options: -p prompt, -e, -a. + +xx. The `readonly' builtin has a new -a option, and the -n option was removed. + +yy. Changes to the `set' builtin: + o new options: -B, -o keyword, -o onecmd, -o history + o options removed: -l, -d, -o nohash + o options changed: +o, -h, -o hashall + o now displays variables in a format that can be re-read as input + +zz. The new `shopt' builtin controls shell optional behavior previously + done by setting and unsetting certain shell variables. + +aaa. The `test' builtin has new operators: -o option, s1 == s2, s1 < s2, + and s1 > s2, where s1 and s2 are strings. + +bbb. There is a new trap, DEBUG, executed after every simple command. + +ccc. The `trap' builtin has a new -p option. + +ddd. The `ulimit' builtin has a new -l option on 4.4BSD-based systems. + +eee. The PS1, PS2, PATH, and IFS variables may now be unset. + +fff. The restricted shell mode has been expanded and is now documented. + +ggg. Security improvements: + o functions are not imported from the environment if running setuid + or with -p + o no startup files are sourced if running setuid or with -p + +hhh. The documentation has been overhauled: the texinfo manual was + expanded, and HTML versions of the man page and texinfo manual + are included. + +iii. Changes to Posix mode: + o Command lookup now finds special builtins before shell functions. + o Failure of a special builtin causes a non-interactive shell to + exit. Failures are defined in the POSIX.2 specification. + o If the `cd' builtin finds a directory to change to using $CDPATH, + the value assigned to PWD when `cd' completes does not contain + any symbolic links. + o A non-interactive shell exits if a variable assignment error + occurs when no command name follows the assignment statements. + o A non-interactive shell exits if the iteration variable in a + `for' statement or the selection variable in a `select' statement + is read-only or another variable assignment error occurs. + o The `<>' redirection operator now opens a file for both stdin and + stdout by default, not just when in posix mode. + o Assignment statements preceding special builtins now persist in + the shell's environment when the builtin completes. + + Posix mode is now completely POSIX.2-compliant (modulo bugs). When + invoked as sh, bash should be completely POSIX.2-compliant. + +jjj. The default value of PS1 is now "\s-\v\$ ". + +kkk. The ksh-like ((...)) arithmetic command syntax has been implemented. + This is exactly equivalent to `let "..."'. + +lll. Integer constants have been extended to base 64. + +mmm. The `ulimit' builtin now sets both hard and soft limits and reports the + soft limit by default. + +2. New Features in Readline + +a. New variables: enable-keypad, input-meta (new name for meta-flag), + mark-directories, visible-stats (now documented), disable-completion, + comment-begin. + +b. New bindable commands: kill-region, copy-region-as-kill, + copy-backward-word, copy-forward-word, set-mark, exchange-point-and-mark, + character-search, character-search-backward, insert-comment, + glob-expand-word, glob-list-expansions, dump-variables, dump-macros. + +c. New emacs keybindings: delete-horizontal-space (M-\), + insert-completions (M-*), possible-completions (M-=). + +d. The history-search-backward and history-search-forward commands were + modified to be the same as previous-line and next-line if point is at + the start of the line. + +e. More file types are available for the visible-stats mode. + +3. Changes of interest in the Bash implementation + +a. There is a new autoconf-based configuration mechanism. + +b. More things have been moved from Posix mode to standard shell behavior. + +c. The trace output (set -x) now inserts quotes where necessary so it can + be reused as input. + +d. There is a compile-time option for a system-wide interactive shell + startup file (disabled by default). + +e. The YACC grammar is smaller and tighter, and all 66 shift-reduce + conflicts are gone. Several parsing bugs have been fixed. + +f. Builtin option parsing has been regularized (using internal_getopt()), + with the exception of `echo', `type', and `set'. + +g. Builtins now return standard usage messages constructed from the + `short doc' used by the help builtin. + +h. Completion now quotes using backslashes by default, but honors + user-supplied quotes. + +i. The GNU libc malloc is available as a configure-time option. + +j. There are more internationalization features; bash uses gettext if + it is available. The $"..." translation syntax uses the current + locale and gettext. + +k. There is better reporting of job termination when the shell is not + interactive. + +l. The shell is somewhat more efficient: it uses a little less memory and + makes fewer system calls. + +4. Changes of interest in the Readline implementation + +a. There is now support for readline `callback' functions. + +b. There is now support for user-supplied input, redisplay, and terminal + preparation functions. + +c. Most of the shell-specific code in readline has been generalized or + removed. + +d. Most of the annoying redisplay bugs have been fixed, notably the problems + with incremental search and excessive redrawing when special characters + appear in the prompt string. + +e. There are new library functions and variables available to application + writers, most having to do with completion and quoting. + +f. The NEWLINE character (^J) is now treated as a search terminator by the + incremental search functions. +------------------------------------------------------------------------------- + +Copying and distribution of this file, with or without modification, +are permitted in any medium without royalty provided the copyright +notice and this notice are preserved. This file is offered as-is, +without any warranty. |