Bash-5.2 Release available

[Chet Ramey]

Introduction
============

The first public release of bash-5.2 is now available with the URLs

ftp://ftp.cwru.edu/pub/bash/bash-5.2.tar.gz
ftp://ftp.gnu.org/pub/gnu/bash/bash-5.2.tar.gz

and from the master branch of the bash git repository
(http://git.savannah.gnu.org/cgit/bash.git/log/)
and the usual GNU mirror sites.

Bash is the GNU Project's Bourne Again SHell, a complete
implementation of the POSIX shell spec, but also with interactive
command line editing, job control on architectures that support it,
csh-like features such as history substitution and brace expansion,
and a slew of other features.  For more information on the features
of Bash that are new to this type of shell, see the file
`doc/bashref.texi'.  There is also a large Unix-style man page.  The
man page is the definitive description of the shell's features. 

This tar file includes the formatted documentation (pdf, postscript,
dvi, info, and html, plus nroffed versions of the manual pages). 

Please use `bashbug' to report bugs with this version.  It is built
and installed at the same time as bash.

Installation
============

Please read the README file first.

Installation instructions are provided in the INSTALL file.

New Features
============

This is an update to the fifth major release of bash.

Read the file NEWS in the bash-5.2 distribution for a complete description
of the new features.  A copy of the relevant portions is included below. 

This release fixes several outstanding bugs in bash-5.1 and introduces
a number of new features.

There are a number of bug fixes, including several bugs that caused the
shell to crash. Complete details are available in the CHANGES file.

The most notable new feature is the rewritten command substitution parsing
code, which calls the bison parser recursively. This replaces the ad-hoc
parsing used in previous versions, and allows better syntax checking and
catches syntax errors much earlier. The shell attempts to do a much better
job of parsing and expanding array subscripts only once; this has visible
effects in the `unset' builtin, word expansions, conditional commands, and
other builtins that can assign variable values as a side effect. The `unset'
builtin allows a subscript of `@' or `*' to unset a key with that value for
associative arrays instead of unsetting the entire array (which you can still
do with `unset arrayname'). There is a new shell option, `patsub_replacement'.
When enabled, a `&' in the replacement string of the pattern substitution
expansion is replaced by the portion of the string that matched the pattern.
Backslash will escape the `&' and insert a literal `&'. This option is enabled
by default. Bash suppresses forking in several additional cases, including
most uses of $(<file).

All the new features are described below.

Readline has new features as well. There is a new option:
`enable-active-region'. This separates control of the active region and
bracketed-paste. It has the same default value as bracketed-paste, and
enabling bracketed paste enables the active region. Users can now turn off
the active region while leaving bracketed paste enabled. Two new bindable
string variables are available; their values are terminal escape sequences
that set the color used to display the active region and turn it off,
respectively. If set, these are used in place of terminal standout mode.
Finally, Readline now checks for changes to locale settings (LC_ALL/LC_CTYPE/
LANG) each time it is called, and modifies the appropriate locale-specific
display and key binding variables when the locale changes.

There are a few incompatible changes between bash-5.1 and bash-5.2. Here-
documents and here-strings use temporary files if the shell compatibility
level is 50 or lower. The `unset' builtin in bash-5.2 treats array subscripts
`@' and `*' differently than previous versions, and differently depending on
whether the array is indexed or associative. Bash-5.2 attempts to prevent
double-expansion of array subscripts under certain circumstances, especially
arithmetic evaluation, by acting as if the `assoc_expand_once' shell option
were set. Set the compatibility level appropriately to revert to previous
behavior; details are in the file COMPAT.

Bash can be linked against an already-installed Readline library rather
than the private version in lib/readline if desired.  Only readline-8.1 and
later versions are able to provide all of the symbols that bash-5.2 requires;
earlier versions of the Readline library will not work correctly. 

A complete list of changes between bash-5.1 and bash-5.2 is available in
the file CHANGES; the complete list is too large to include in this
message. 

Readline
========

Also available is a new release of the standalone Readline library,
version 8.2, with its own configuration scripts and Makefiles. 
It can be retrieved with the URLs

ftp://ftp.cwru.edu/pub/bash/readline-8.2.tar.gz
ftp://ftp.gnu.org/pub/gnu/readline/readline-8.2.tar.gz

and from the master branch of the GNU readline git repository
(http://git.savannah.gnu.org/cgit/readline.git/log/)
and the usual GNU mirror sites.

The formatted Readline documentation is included in the readline
distribution tar file.

The changes in Readline are described in a separate announcement.

As always, thanks for your help.

Chet

+========== NEWS ==========+
This is a terse description of the new features added to bash-5.2 since
the release of bash-5.1.  As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.

1. New Features in Bash

a. The bash malloc returns memory that is aligned on 16-byte boundaries.

b. There is a new internal timer framework used for read builtin timeouts.

c. Rewrote the command substitution parsing code to call the parser recursively
   and rebuild the command string from the parsed command. This allows better
   syntax checking and catches errors much earlier. Along with this, if
   command substitution parsing completes with here-documents remaining to be
   read, the shell prints a warning message and reads the here-document bodies
   from the current input stream.

d. The `ulimit' builtin now treats an operand remaining after all of the options
   and arguments are parsed as an argument to the last command specified by
   an option. This is for POSIX compatibility.

e. Here-document parsing now handles $'...' and $"..." quoting when reading the
   here-document body.

f. The `shell-expand-line' and `history-and-alias-expand-line' bindable readline
   commands now understand $'...' and $"..." quoting.

g. There is a new `spell-correct-word' bindable readline command to perform
   spelling correction on the current word.

h. The `unset' builtin now attempts to treat arguments as array subscripts
   without parsing or expanding the subscript, even when `assoc_expand_once'
   is not set.

i. There is a default value for $BASH_LOADABLES_PATH in config-top.h.

j. Associative array assignment and certain instances of referencing (e.g.,
   `test -v' now allow `@' and `*' to be used as keys.

k. Bash attempts to expand indexed array subscripts only once when executing
   shell constructs and word expansions.

l. The `unset' builtin allows a subscript of `@' or `*' to unset a key with
   that value for associative arrays instead of unsetting the entire array
   (which you can still do with `unset arrayname'). For indexed arrays, it
   removes all elements of the array without unsetting it (like `A=()').

m. Additional builtins (printf/test/read/wait) do a better job of not
   parsing array subscripts if array_expand_once is set.

n. New READLINE_ARGUMENT variable set to numeric argument for readline commands
   defined using `bind -x'.

o. The new `varredir_close' shell option causes bash to automatically close
   file descriptors opened with {var}<fn and other styles of varassign
   redirection unless they're arguments to the `exec' builtin.

p. The `$0' special parameter is now set to the name of the script when running
   any (non-interactive) startup files such as $BASH_ENV.

q. The `enable' builtin tries to load a loadable builtin using the default
   search path if `enable name' (without any options) attempts to enable a
   non-existent builtin.

r. The `printf' builtin has a new format specifier: %Q. This acts like %q but
   applies any specified precision to the original unquoted argument, then
   quotes and outputs the result.

s. The new `noexpand_translations' option controls whether or not the translated
   output of $"..." is single-quoted.

t. There is a new parameter transformation operator: @k. This is like @K, but
   expands the result to separate words after word splitting.

u. There is an alternate array implementation, selectable at `configure' time,
   that optimizes access speed over memory use (use the new configure
    --enable-alt-array-implementation option).

v. If an [N]<&WORD- or [N]>&WORD- redirection has WORD expand to the empty
   string, treat the redirection as [N]<&- or [N]>&- and close file descriptor
   N (default 0).

w. Invalid parameter transformation operators are now invalid word expansions,
   and so cause fatal errors in non-interactive shells.

x. New shell option: patsub_replacement. When enabled, a `&' in the replacement
   string of the pattern substitution expansion is replaced by the portion of
   the string that matched the pattern. Backslash will escape the `&' and
   insert a literal `&'.

y. `command -p' no longer looks in the hash table for the specified command.

z. The new `--enable-translatable-strings' option to `configure' allows $"..."
   support to be compiled in or out.

aa. The new `globskipdots' shell option forces pathname expansion never to
    return `.' or `..' unless explicitly matched. It is enabled by default.

bb. Array references using `@' and `*' that are the value of nameref variables
    (declare -n ref='v[@]' ; echo $ref) no longer cause the shell to exit if
    set -u is enabled and the array (v) is unset.

cc. There is a new bindable readline command name:
    `vi-edit-and-execute-command'.

dd. In posix mode, the `printf' builtin checks for the `L' length modifier and
    uses long double for floating point conversion specifiers if it's present,
    double otherwise.

ee. The `globbing' completion code now takes the `globstar' option into account.

ff. `suspend -f' now forces the shell to suspend even if job control is not
   currently enabled.

gg. Since there is no `declare -' equivalent of `local -', make sure to use
    `local -' in the output of `local -p'.

2. New Features in Readline

a. There is now an HS_HISTORY_VERSION containing the version number of the
   history library for applications to use.

b. History expansion better understands multiple history expansions that may
   contain strings that would ordinarily inhibit history expansion (e.g.,
   `abc!$!$').

c. There is a new framework for readline timeouts, including new public
   functions to set timeouts and query how much time is remaining before a
   timeout hits, and a hook function that can trigger when readline times
   out. There is a new state value to indicate a timeout.

d. Automatically bind termcap key sequences for page-up and page-down to
   history-search-backward and history-search-forward, respectively.

e. There is a new `fetch-history' bindable command that retrieves the history
   entry corresponding to its numeric argument. Negative arguments count back
   from the end of the history.

f. `vi-undo' is now a bindable command.

g. There is a new option: `enable-active-region'. This separates control of
   the active region and bracketed-paste. It has the same default value as
   bracketed-paste, and enabling bracketed paste enables the active region.
   Users can now turn off the active region while leaving bracketed paste
   enabled.

h. rl_completer_word_break_characters is now `const char *' like
   rl_basic_word_break_characters.

i. Readline looks in $LS_COLORS for a custom filename extension
   (*.readline-colored-completion-prefix) and uses that as the default color
   for the common prefix displayed when `colored-completion-prefix' is set.

j. Two new bindable string variables: active-region-start-color and
   active-region-end-color. The first sets the color used to display the
   active region; the second turns it off. If set, these are used in place
   of terminal standout mode.

k. New readline state (RL_STATE_EOF) and application-visible variable
   (rl_eof_found) to allow applications to detect when readline reads EOF
   before calling the deprep-terminal hook.

l. There is a new configuration option: --with-shared-termcap-library, which
   forces linking the shared readline library with the shared termcap (or
   curses/ncurses/termlib) library so applications don't have to do it.

m. Readline now checks for changes to locale settings (LC_ALL/LC_CTYPE/LANG)
   each time it is called, and modifies the appropriate locale-specific display
   and key binding variables when the locale changes.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/