Log Message:
Update to 4.1:

This document details the changes between this version, bash-4.1-rc,
and the previous version, bash-4.1-beta.

1.  Changes to Bash

a.  Fixed a bug that caused printf to not return a partial value when it
    encountered an error while converting an integer argument.

b.  Fixed a bug that caused setting one of the compatNN options to not
    turn off the others.

c.  The (undocumented) --wordexp option is no longer included by default.

d.  Fixed a bug in conditional command execution that caused it to not
    correctly ignore the exit status under certain circumstances.

e.  Added a configure-time check for correctly-working asprintf/snprintf.

f.  Fixed some problems with line number calculation and display when sourcing
    a file in an interactive shell.

g.  Fixed a bug that caused the shell to crash when using `declare -A foo=bar'.

h.  Fixed a bug that caused an off-by-one error when calculating the directories
    to display with the PROMPT_DIRTRIM option.

2.  Changes to Readline

a.  Fixed a bug that caused applications using the callback interface to not
    react to SIGINT (or other signals) until another character arrived.

------------------------------------------------------------------------------
This document details the changes between this version, bash-4.1-beta,
and the previous version, bash-4.1-alpha.

1.  Changes to Bash

a.  Fixed a bug in mapfile that caused the shell to crash if it was passed the
    name of an associative array.

b.  Fixed a bug that caused the shell to incorrectly split case patterns if
    they contained characters in $IFS.

c.  Fixed a bug that caused the shell to set $? to the wrong value when using
    a construct ending with a variable assignment with set -x enabled and PS4
    containing a command substitution.

d.  Fixed a bug that caused the shell to read commands incorrectly if an
    expansion error occurred under certain conditions in a user-specified
    subshell.

e.  Fixed a bug that caused the shell to set $? incorrectly if a parse error
    occurred in an evaluation context ("eval", trap command, dot \ 
script, etc.)

f.  Fixed a bug that caused the shell to attempt command substitution
    completion within a single-quoted string.

g.  Fixed a bug that caused the shell to insert an extra single quote during
    word completion.

h.  Fixed a bug that caused the shell to crash if invoked with the environment
    variable EMACS having a null value.

i.  Fixed a bug that caused bash to incorrectly report the presence of new
    mail in a `maildir' environment.

j.  Fixed a bug that caused the shell to not recognize a here-document ending
    delimiter inside a command substitution.

k.  Fixed a bug that caused the shell to crash when a a dynamic array variable
    was assigned a scalar value.

2.  Changes to Readline

3.  New Features in Bash

a.  The mapfile/readarray builtin no longer stores the commands it invokes via
    callbacks in the history list.

b.  There is a new `compat40' shopt option.

c.  The < and > operators to [[ do string comparisons using the current locale
    only if the compatibility level is greater than 40 (set to 41 by default).

4.  New Features in Readline

------------------------------------------------------------------------------
This document details the changes between this version, bash-4.1-alpha,
and the previous version, bash-4.0-release.

1.  Changes to Bash

a.  Fixed bugs in the parser involving new parsing of the commands contained
    in command substitution when the substitution is read.

b.  Fixed a bug that caused the shell to dump core when performing programmable
    completion using a shell function.

c.  Fixed a bug in `mapfile' that caused it to invoke callbacks at the wrong
    time.

d.  Fixed a bug that caused the shell to dump core when listing jobs in the
    `exit' builtin.

e.  Fixed several bugs encountered when reading subscripts in associative
    array assignments and expansions.

f.  Fixed a bug that under some circumstances caused an associative array to
    be converted to an indexed array.

g.  Fixed a bug that caused syntax errors and SIGINT interrupts to not set
    $? to a value > 128.

h.  Fixed a bug that caused the shell to remove FIFOs associated with process
    substitution inside shell functions.

i.  Fixed a bug that caused terminal attributes to not be reset when the
    `read' builtin timed out.

j.  Fixed a bug in brace expansion that caused unwanted zero padding of the
    expanded terms.

k.  Fixed a bug that prevented the |& construct from working as intended when
    used with a simple command with additional redirections.

l.  Fixed a bug with the case statment ;& terminator that caused the shell to
    dereference a NULL pointer.

m.  Fixed a bug that caused assignment statements or redirections preceding
    a simple command name to inhibit alias expansion.

n.  Fixed the behavior of `set -u' to conform to the latest Posix interpretation:
    every expansion of an unset variable except $@ and $* will cause the
    shell to exit.

o.  Fixed a bug that caused double-quoted expansions of $* inside word
    expansions like ${x#$*} to not expand properly when $IFS is empty.

p.  Fixed a bug that caused traps to set $LINENO to the wrong value when they
    execute.

q.  Fixed a bug that caused off-by-one errors when computing history lines in
    the `fc' builtin.

r.  Fixed a bug that caused some terminating signals to not exit the shell
    quickly enough, forcing the kernel to send the signal (e.g., SIGSEGV)
    multiple times.

s.  Fixed a bug that caused the shell to attempt to add empty lines to the
    history list when reading here documents.

t.  Made some internal changes that dramatically speeds up sequential indexed
    array access.

u.  Fixed a bug that caused the shell to write past the end of a string when
    completing a double-quoted string ending in a backslash.

v.  Fixed a bug that caused the shell to replace too many characters when a
    pattern match was null in a ${foo//bar} expansion.

w.  Fixed bugs in the expansion of ** that caused duplicate directory names
    and the contents of the current directory to be omitted.

x.  Fixed a bug that caused $? to not be set correctly when referencing an
    unset variable with set -u and set -e enabled.

y.  Fixed a bug caused by executing an external program from the DEBUG trap
    while a pipeline was running.  The effect was to disturb the pipeline
    state, occasionally causing it to hang.

z.  Fixed a bug that caused the ** glob expansion to dump core if it
    encountered an unsearchable directory.

aa. Fixed a bug that caused `command -v' and `command -V' to not honor the
    path set by the -p option.

bb. Fixed a bug that caused brace expansion to take place too soon in some
    compound array assignments.

cc. Fixed a bug that caused programmable completion functions' changes to
    READLINE_POINT to not be reflected back to readline.

dd. Fixed a bug that caused the shell to dump core if a trap was executed
    during a shell assignment statement.

ee. Fixed an off-by-one error when computing the number of positional
    parameters for the ${@:0:n} expansion.

ff. Fixed a problem with setting COMP_CWORD for programmable completion
    functions that could leave it set to -1.

gg. Fixed a bug that caused the ERR trap to be triggered in some cases where
    `set -e' would not have caused the shell to exit.

hh. Fixed a bug that caused changes made by `compopt' to not persist past the
    completion function in which compopt was executed.

ii. Fixed a bug that caused the list of hostname completions to not be cleared
    when HOSTNAME was unset.

jj. Fixed a bug that caused variable expansion in here documents to look in
    any temporary environment.

kk. Bash and readline can now convert file names between precomposed and
    decomposed Unicode on Mac OS X ("keyboard" and file system forms,
    respectively).  This affects filename completion (using new
    rl_filename_rewrite_hook), globbing, and readline redisplay.

ll. The ERR and EXIT traps now see a non-zero value for $? when a parser
    error after set -e has been enabled causes the shell to exit.

mm. Fixed a bug that in brace expansion that caused zero-prefixed terms to
    not contain the correct number of digits.

nn. Fixed a bug that caused the shell to free non-allocated memory when
    unsetting an associative array which had had a value implicitly assigned
    to index "0".

oo. Fixed a memory leak in the ${!prefix@} expansion.

pp. Fixed a bug that caused printf to not correctly report all write errors.

qq. Fixed a bug that caused single and double quotes to act as delimiters
    when splitting a command line into words for programmable completion.

rr. Fixed a bug that caused ** globbing that caused **/path/* to match every
    directory, not just those matching `path'.

ss. Fixed a bug that caused the shell to dump core when running `help' without
    arguments if the terminal width was fewer than 7 characters.

2.  Changes to Readline

a.  The SIGWINCH signal handler now avoids calling the redisplay code if
    one arrives while in the middle of redisplay.

b.  Changes to the timeout code to make sure that timeout values greater
    than one second are handled better.

c.  Fixed a bug in the redisplay code that was triggered by a prompt
    containing invisible characters exactly the width of the screen.

d.  Fixed a bug in the redisplay code encountered when running in horizontal
    scroll mode.

e.  Fixed a bug that prevented menu completion from properly completing
    filenames.

f.  Fixed a redisplay bug caused by a multibyte character causing a line to
    wrap.

g.  Fixed a bug that caused key sequences of two characters to not be
    recognized when a longer sequence identical in the first two characters
    was bound.

h.  Fixed a bug that caused history expansion to be attempted on $'...'
    single-quoted strings.

i.  Fixed a bug that caused incorrect redisplay when the prompt contained
    multibyte characters in an `invisible' sequence bracketed by \[ and
    \].

j.  Fixed a bug that caused history expansion to short-circuit after
    encountering a multibyte character.

3.  New Features in Bash

a.  Here-documents within $(...) command substitutions may once more be
    delimited by the closing right paren, instead of requiring a newline.

b.  Bash's file status checks (executable, readable, etc.) now take file
    system ACLs into account on file systems that support them.

c.  Bash now passes environment variables with names that are not valid
    shell variable names through into the environment passed to child
    processes.

d.  The `execute-unix-command' readline function now attempts to clear and
    reuse the current line rather than move to a new one after the command
    executes.

e.  `printf -v' can now assign values to array indices.

f.  New `complete -E' and `compopt -E' options that work on the "empty"
    completion: completion attempted on an empty command line.

g.  New complete/compgen/compopt -D option to define a `default' completion:
    a completion to be invoked on command for which no completion has been
    defined.  If this function returns 124, programmable completion is
    attempted again, allowing a user to dynamically build a set of completions
    as completion is attempted by having the default completion function
    install individual completion functions each time it is invoked.

h.  When displaying associative arrays, subscripts are now quoted.

i.  Changes to dabbrev-expand to make it more `emacs-like': no space appended
    after matches, completions are not sorted, and most recent history entries
    are presented first.

j.  The [[ and (( commands are now subject to the setting of `set -e' and the
    ERR trap.

k.  The source/. builtin now removes NUL bytes from the file before attempting
    to parse commands.

l.  There is a new configuration option (in config-top.h) that forces bash to
    forward all history entries to syslog.

m.  A new variable $BASHOPTS to export shell options settable using `shopt' to
    child processes.

n.  There is a new confgure option that forces the extglob option to be
    enabled by default.

o.  New variable $BASH_XTRACEFD; when set to an integer bash will write xtrace
    output to that file descriptor.

p.  If the optional left-hand-side of a redirection is of the form {var}, the
    shell assigns the file descriptor used to $var or uses $var as the file
    descriptor to move or close, depending on the redirection operator.

q.  The < and > operators to the [[ conditional command now do string
    comparison according to the current locale.

r.  Programmable completion now uses the completion for `b' instead of `a'
    when completion is attempted on a line like: a $(b c.

s.  Force extglob on temporarily when parsing the pattern argument to
    the == and != operators to the [[ command, for compatibility.

t.  Changed the behavior of interrupting the wait builtin when a SIGCHLD is
    received and a trap on SIGCHLD is set to be Posix-mode only.

u.  The read builtin has a new `-N nchars' option, which reads exactly NCHARS
    characters, ignoring delimiters like newline.

4.  New Features in Readline

a.  New bindable function: menu-complete-backward.

b.  In the vi insertion keymap, C-n is now bound to menu-complete by default,
    and C-p to menu-complete-backward.

c.  When in vi command mode, repeatedly hitting ESC now does nothing, even
    when ESC introduces a bound key sequence.  This is closer to how
    historical vi behaves.

d.  New bindable function: skip-csi-sequence.  Can be used as a default to
    consume key sequences generated by keys like Home and End without having
    to bind all keys.

e.  New application-settable function: rl_filename_rewrite_hook.  Can be used
    to rewite or modify filenames read from the file system before they are
    compared to the word to be completed.

f.  New bindable variable: skip-completed-text, active when completing in the
    middle of a word.  If enabled, it means that characters in the completion
    that match characters in the remainder of the word are "skipped" rather
    than inserted into the line.

g.  The pre-readline-6.0 version of menu completion is available as
    "old-menu-complete" for users who do not like the readline-6.0 version.

h.  New bindable variable: echo-control-characters.  If enabled, and the
    tty ECHOCTL bit is set, controls the echoing of characters corresponding
    to keyboard-generated signals.

i.  New bindable variable: enable-meta-key.  Controls whether or not readline
    sends the smm/rmm sequences if the terminal indicates it has a meta key
    that enables eight-bit characters.