+o There is a new variable, $BASHPID, which always returns the process id of
+ the current shell.
+
+o 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.
+
+o There is a new `checkjobs' option that causes the shell to check for and
+ report any running or stopped jobs at exit.
+
+o The programmable completion code exports a new COMP_TYPE variable, set to
+ a character describing the type of completion being attempted.
+
+o The programmable completion code exports a new COMP_KEY variable, set to
+ the character that caused the completion to be invoked (e.g., TAB).
+
+o The programmable completion code now uses the same set of characters as
+ readline when breaking the command line into a list of words.
+
+o The block multiplier for the ulimit -c and -f options is now 512 when in
+ Posix mode, as Posix specifies.
+
+o 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.
+
+o 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.
+
+o The `ulimit' builtin now has new -b (socket buffer size) and -T (number
+ of threads) options.
+
+o There is a new `compopt' builtin that allows completion functions to modify
+ completion options for existing completions or the completion currently
+ being executed.
+
+o The `read' builtin has a new -i option which inserts text into the reply
+ buffer when using readline.
+
+o A new `-E' option to the complete builtin allows control of the default
+ behavior for completion on an empty line.
+
+o There is now limited support for completing command name words containing
+ globbing characters.
+
+o 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.
+
+o There is a new `mapfile' builtin to populate an array with lines from a
+ given file.
+
+o 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.
+
+o 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.
+
+o There is a new shell option: `dirspell'. When enabled, the filename
+ completion code performs spelling correction on directory names during
+ completion.
+
+o The `-t' option to the `read' builtin now supports fractional timeout
+ values.
+
+o 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.
+
+o 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.
+
+o 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.
+
+o There is a new >>& redirection operator, which appends the standard output
+ and standard error to the named file.
+
+o The parser now understands `|&' as a synonym for `2>&1 |', which redirects
+ the standard error for a command through a pipe.
+
+o 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.
+
+o 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.
+
+o 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 `...'.
+
+o 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.
+
+o The shell provides associative array variables, with the appropriate
+ support to create, delete, assign values to, and expand them.
+
+o 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.
+
+o 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.
+
+o 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.
+
+o CDPATH and GLOBIGNORE are ignored when the shell is running in privileged
+ mode.
+
+o 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.
+
+o 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.
+
+Bash-3.2 contained the following new features:
+
+o Bash-3.2 now checks shell scripts for NUL characters rather than non-printing
+ characters when deciding whether or not a script is a binary file.
+
+o Quoting the string argument to the [[ command's =~ (regexp) operator now
+ forces string matching, as with the other pattern-matching operators.
+
+Bash-3.1 contained the following new features:
+
+o Bash-3.1 may now be configured and built in a mode that enforces strict
+ POSIX compliance.
+
+o The `+=' assignment operator, which appends to the value of a string or
+ array variable, has been implemented.
+
+o It is now possible to ignore case when matching in contexts other than
+ filename generation using the new `nocasematch' shell option.
+
+Bash-3.0 contained the following new features:
+
+o Features to support the bash debugger have been implemented, and there
+ is a new `extdebug' option to turn the non-default options on
+
+o HISTCONTROL is now a colon-separated list of options and has been
+ extended with a new `erasedups' option that will result in only one
+ copy of a command being kept in the history list
+
+o Brace expansion has been extended with a new {x..y} form, producing
+ sequences of digits or characters
+
+o Timestamps are now kept with history entries, with an option to save
+ and restore them from the history file; there is a new HISTTIMEFORMAT
+ variable describing how to display the timestamps when listing history
+ entries
+
+o The `[[' command can now perform extended regular expression (egrep-like)
+ matching, with matched subexpressions placed in the BASH_REMATCH array
+ variable
+
+o A new `pipefail' option causes a pipeline to return a failure status if
+ any command in it fails
+
+o The `jobs', `kill', and `wait' builtins now accept job control notation
+ in their arguments even if job control is not enabled
+
+o The `gettext' package and libintl have been integrated, and the shell
+ messages may be translated into other languages
+
+Bash-2.05b introduced the following new features:
+
+o support for multibyte characters has been added to both bash and readline
+
+o the DEBUG trap is now run *before* simple commands, ((...)) commands,
+ [[...]] conditional commands, and for ((...)) loops
+
+o the shell now performs arithmetic in the largest integer size the machine
+ supports (intmax_t)
+
+o there is a new \D{...} prompt expansion; passes the `...' to strftime(3)
+ and inserts the result into the expanded prompt
+
+o there is a 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).
+
+o `read' has a new `-u fd' option to read from a specified file descriptor
+
+o 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
+
+o 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
+
+Bash-2.05a introduced the following new features:
+
+o The `printf' builtin has undergone major work
+
+o There is a new read-only `shopt' option: login_shell, which is set by
+ login shells and unset otherwise
+
+o New `\A' prompt string escape sequence; expanding to time in 24-hour
+ HH:MM format
+
+o New `-A group/-g' option to complete and compgen; goes group name
+ completion
+
+o New [+-]O invocation option to set and unset `shopt' options at startup
+
+o ksh-like `ERR' trap
+
+o `for' loops now allow empty word lists after the `in' reserved word
+
+o new `hard' and `soft' arguments for the `ulimit' builtin
+
+o Readline can be configured to place the user at the same point on the line
+ when retrieving commands from the history list
+
+o Readline can be configured to skip `hidden' files (filenames with a leading
+ `.' on Unix) when performing completion
+
+Bash-2.05 introduced the following new features:
+
+o This version has once again reverted to using locales and strcoll(3) when
+ processing pattern matching bracket expressions, as POSIX requires.
+o Added a new `--init-file' invocation argument as a synonym for `--rcfile',
+ per the new GNU coding standards.
+o The /dev/tcp and /dev/udp redirections now accept service names as well as
+ port numbers.
+o `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
+o A new loadable builtin, realpath, which canonicalizes and expands symlinks
+ in pathname arguments.
+o When `set' is called without options, it prints function defintions 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.
+
+Bash-2.04 introduced the following new features:
+
+o Programmable word completion with the new `complete' and `compgen' builtins;
+ examples are provided in examples/complete/complete-examples
+o `history' has a new `-d' option to delete a history entry
+o `bind' has a new `-x' option to bind key sequences to shell commands
+o The prompt expansion code has new `\j' and `\l' escape sequences
+o The `no_empty_cmd_completion' shell option, if enabled, inhibits
+ command completion when TAB is typed on an empty line
+o `help' has a new `-s' option to print a usage synopsis
+o New arithmetic operators: var++, var--, ++var, --var, expr1,expr2 (comma)
+o New ksh93-style arithmetic for command:
+ for ((expr1 ; expr2; expr3 )); do list; done
+o `read' has new options: `-t', `-n', `-d', `-s'
+o The redirection code handles several filenames specially: /dev/fd/N,
+ /dev/stdin, /dev/stdout, /dev/stderr
+o The redirection code now recognizes /dev/tcp/HOST/PORT and
+ /dev/udp/HOST/PORT and tries to open a TCP or UDP socket, respectively,
+ to the specified port on the specified host
+o The ${!prefix*} expansion has been implemented
+o A new FUNCNAME variable, which expands to the name of a currently-executing
+ function
+o The GROUPS variable is no longer readonly
+o A new shopt `xpg_echo' variable, to control the behavior of echo with
+ respect to backslash-escape sequences at runtime
+o The NON_INTERACTIVE_LOGIN_SHELLS #define has returned
+
+The version of Readline released with Bash-2.04, Readline-4.1, had several
+new features as well:
+
+o Parentheses matching is always compiled into readline, and controllable
+ with the new `blink-matching-paren' variable
+o The history-search-forward and history-search-backward functions now leave
+ point at the end of the line when the search string is empty, like
+ reverse-search-history, and forward-search-history
+o A new function for applications: rl_on_new_line_with_prompt()
+o New variables for applications: rl_already_prompted, and rl_gnu_readline_p
+
+
+Bash-2.03 had very few new features, in keeping with the convention
+that odd-numbered releases provide mainly bug fixes. A number of new
+features were added to Readline, mostly at the request of the Cygnus
+folks.
+
+A new shopt option, `restricted_shell', so that startup files can test
+ whether or not the shell was started in restricted mode
+Filename generation is now performed on the words between ( and ) in
+ compound array assignments (this is really a bug fix)
+OLDPWD is now auto-exported, as POSIX.2 requires
+ENV and BASH_ENV are read-only variables in a restricted shell
+Bash may now be linked against an already-installed Readline library,
+ as long as the Readline library is version 4 or newer
+All shells begun with the `--login' option will source the login shell
+ startup files, even if the shell is not interactive
+
+There were lots of changes to the version of the Readline library released
+along with Bash-2.03. For a complete list of the changes, read the file
+CHANGES in the Bash-2.03 distribution.
+
+Bash-2.02 contained the following new features:
+
+a new version of malloc (based on the old GNU malloc code in previous
+ bash versions) that is more page-oriented, more conservative
+ with memory usage, does not `orphan' large blocks when they
+ are freed, is usable on 64-bit machines, and has allocation
+ checking turned on unconditionally
+POSIX.2-style globbing character classes ([:alpha:], [:alnum:], etc.)
+POSIX.2-style globbing equivalence classes
+POSIX.2-style globbing collating symbols
+the ksh [[...]] extended conditional command
+the ksh egrep-style extended pattern matching operators
+a new `printf' builtin
+the ksh-like $(<filename) command substitution, which is equivalent to
+ $(cat filename)
+new tilde prefixes that expand to directories from the directory stack
+new `**' arithmetic operator to do exponentiation
+case-insensitive globbing (filename expansion)
+menu completion a la tcsh
+`magic-space' history expansion function like tcsh
+the readline inputrc `language' has a new file inclusion directive ($include)
+
+Bash-2.01 contained only a few new features: