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-------------------------------------
CHANGES FROM PREVIOUS VERSIONS OF ZSH
-------------------------------------

Note also the list of incompatibilities in the README file.

Changes from 5.0.7 to 5.0.8
---------------------------

- Global aliases can be created for syntactic tokens such as command
  separators (";", "&", "|", "&&", "||"), redirection operators, etc.
  Use at your own risk!  The POSIX_ALIASES option is interpreted more
  strictly to prevent expansion of these and other alias names containing
  quotes, glob metacharacters, parameter references, etc.

- There have been various further improvements to builtin handling
  with the POSIX_BUILTINS option (off by default) for compatibility with
  the POSIX standard.

- 'whence -v' is now more informative, and 'whence -S' shows you
  how a full chain of symbolic links resolves to a command.

- The 'p' parameter flag now allows an argument to be specified
  as a reference to a variable, e.g. ${(ps.$sep.)foo} to split $foo
  on a string given by $sep.

- Elements of the watch variable may now be patterns.

- The logic for retrying history locking has been improved.

- Some rationalisations have been made to the zsh/db/gdbm module that
  should make it more useful and predictable in operation.

Changes from 5.0.0 to 5.0.7
---------------------------

- Numeric constants encountered in mathematical expressions (but not other
  contexts) can contain underscores as separators that will be ignored on
  evaluation, as allowed in other scripting languages.  For example,
  0xFFFF_FFFF, or 3.141_592_654.  From 5.0.6 this is also available
  in output, e.g.
    setopt cbases
    zmodload zsh/mathfunc
    print $(( [#16_4] 2**32 - 1 )) $(( [#_3] 4 * atan(1.0) ))

- "functions -T" turns on tracing for the specified function(s) only,
  similar to "functions -t" except that tracing is turned off for any
  functions called from the specified one(s) that don't also have the -t
  or -T flag.

- The option FORCE_FLOAT has been added to force all arithmetic constants
  to be treated as floating point.  This is most useful locally within
  functions or scripts performing floating point calculations.

- The default $fpath/$FPATH is now designed to include
  /usr/local/share/zsh/site-functions unless the installer has
  specifically decided to use another path, i.e. regardless of
  the standard installation location.  This directory does not need to
  exist.  Sites that set an explicit site directory can put that in
  /etc/zshenv as before.  The intention of the new path element is to
  increase the likelihood that locally added functions can be found with
  the shell running "out of the box", unless the shell has been
  deliberately configured differently by the installer for some special
  purpose.

- Individual pattern characters can be disabled.  For example, to allow '^'
  to be an ordinary character even if the option EXTENDED_GLOB is set, use
  "disable -p '^'".

- The variable editing builtin vared can be given custom editing widgets
  for initialisation and finishing.

- The line editor's capability for listening on file descriptors
  additional to the terminal has been enhanced so that the handler for
  such file descriptors can be a line editor widget.  Previously the
  handler always behaved as a standard shell function.

- Hooks for adding history (the function zshaddhistory and the
  array zshaddhistory_functions) can return status 2 to indicate that
  history is to be saved internally within the shell but not written.

- In file completion, the recursive-files style can be set to an array of
  patterns to match against "$PWD/".  In any matched location, it is
  possible to complete files in arbitrarily deep subdirectories without
  needing to type the directory prefix.  See example in the zshcompsys
  manual.

- The _user_expand completer now allows expansion functions in the
  user-expand files to return a string in REPLY that will be used to name
  the set of expansions returned.

- The parameter HISTORY_IGNORE may be set to a pattern which matches
  lines in the internal history that are to be omitted from the history
  file at file write time.  This differs from history changes made in
  the zshaddhistory hook or by the HIST_IGNORE_* options, all of which
  take effect immediately on the internal history list itself.

- The parameter ZLE_RPROMPT_INDENT can be set to 0 to remove the space
  before the right hand side of the screen (this causes problems with
  some terminals).  It is not special and is not set by default; the
  effect in that case is as if it was 1, as in previous versions.

- If the option EXTENDED_GLOB is in effect, it is possible to force
  globbing within conditional code using the [[ ... ]] syntax by flagging
  that a certain string is a glob using the (#q) glob qualifier syntax.
  The resulting glob is treated as a single argument.  For example,
  [[ -n *.c(#qN) ]] tests whether there are any .c files in the current
  directory.

- In prompt strings, the %N(l.true.false) conditional (line length) and
  the %N<..< and %N>..> truncation operators now accept negative values
  of N, which count the remaining space to the opposite margin (positive
  values of N still count the space used since the start of the prompt).
  In PS1 and PROMPT, this counts to the right margin, whereas in RPS1 and
  RPROMPT, it counts to the left margin (not to the opposite prompt).

- Also in prompt strings, %e or the equivalent test %(e..) are used to
  output or test the execution / evaluation depth of a shell
  construct within functions etc.  This is useful in $PS4.

- Another new prompt feature is the %. escape within time strings, for
  example %D{%H:%M:%S.%.}.  It provides zero-padded decimal fractions of a
  second; by default milliseconds are shown, but the number of digits may
  be indicated from 1 to 6, e.g. "%6.".  (Note this is part of the
  extensions to strftime() formats rather than basic prompt escapes.)

- The operators :^ and :^^ in parameter substitution allow for array
  zipping in the form ${name:^array}. With the :^ operator, all entries
  in $name and $array will be output in alternating order. With :^ the
  longer array is trimmed whereas the :^^ operator repeats the shorter
  array enough to match the longer array.

- The value of $? when a job becomes stopped is now the signal number plus
  128, for compatibility with other shells.  Note that different operating
  systems use different values e.g. for SIGTSTP, so it is not possible in
  portable scripts to detect stopped jobs by comparing to a fixed number.
  Also, the value of $pipestatus is now updated when a job stops, not just
  when it exits.

- Redirections applied to function definitions take effect when the
  function is executed, not when it is defined.  Other shells already
  work this way.  For example,
    fn() { echo hello } >~/logfile
  Running fn writes "hello" to logfile.  In older versions of the shell
  it would create an empty file at the point of definition.

Changes between 4.2 and 5.0.0
-----------------------------

The following changes first appeared in the 4.3 series of releases;
see also the file Etc/NEWS-4.3.

Here is a summary of the most significant changes:

- Multibyte characters strings are supported throughout the shell.
  Various options, editor features, and expansion flags have been
  added to aid in using them.

- The following new options have appeared: COMBINING_CHARS,
  DEBUG_BEFORE_CMD, HASH_EXECUTABLES_ONLY, HIST_FCNTL_LOCK,
  HIST_LEX_WORDS, HIST_SAVE_BY_COPY, MULTIBYTE, NO_MULTI_FUNCDEF,
  PATH_SCRIPT, POSIX_ALIASES, POSIX_CD, POSIX_JOBS, POSIX_STRINGS,
  POSIX_TRAPS, PROMPT_SP, SOURCE_TRACE.

- Highlighting and colouring of the command line is supported.

- Job control is supported in non-interactive shells and subshells.

- The zshroadmap manual page provides a slightly more helpful
  introduction to the shell manual than was previously available.

- There have been some notable enhancements to POSIX comptability
  when the shell is in a corresponding emulation (e.g. "emulate sh").

Expansion (parameters, globbing, etc.) and redirection
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

- The character group tests [[:IDENT:]], [[:IFS:]], [[:IFSSPACE:]],
  [[:WORD:]] in patterns allow testing if a character can be
  part of an identifier, is an IFS character, is an IFS whitespace
  character, or is considered part of the word using the line editor's
  logic based on the shell variable WORDCHARS.

- In extended globbing, "(#cN,M)" means "match the preceding group
  at least N but no more than M times".

- The glob qualifier P can be used with an argument to add an extra
  word before each glob match.

- The syntax ~[...] provides dynamic directory naming by means
  of the shell function zsh_directory_name or associated hook functions.
  This is useful for expanding paths with many variable components as
  commonly found in software development.

- Parameter substitution has the ${NAME:OFFSET} and ${NAME:OFFSET:LENGTH}
  syntax for compatibility with other shells (and zero-based indexing
  is used to enhance compatibility).  LENGTH may be negative to count
  from the end.

- The arbitrary limit on parameter subscripts (262144) has been removed.
  As it was not configurable and tested in an inconvenient place it
  was deemed preferable to remove it completely.  The limit was originally
  introduced to prevent accidental creation of a large parameter array
  by typos that generated assignments along the lines of "12345678=0".
  The general advice is not to do that.

- The parameter substitution flag (D) abbreviates directories in parameters
  using the familiar ~ form.

- The parameter substitution flag (g) can take delimited arguments o, e and
  c to provide echo- and print-style expansion: (g::) provides basic
  echo-style expansion; (g:e:) provides the extended capabilities of
  print; (g:o:) provides octal escapes without a leading zero; (g:c:)
  additionally expands "^c" style control characters as for bindkey.
  Options may be combined, e.g. (g:eoc:).

- The parameter substitution flag (m) indicates that string lengths used
  calculated by the (l) and (r) flags or the # operator should take
  account of the printing width of characters in multibyte mode, whether
  0, 1 or more.  (mm) causes printing characters to count as 1 and
  non-printing chracters to count as 0.

- The parameter substitution flag (q-) picks the most minimal way of
  quoting the parameter words, to make the result as readable as possible.

- The parameter substitution flag (Z), a variant of (z), takes arguments
  describing how to split a variable using shell syntax: (Z:c:) parses
  comments as strings (the default is not to treat comment characters
  specially); (Z:C:) parses comments and strips them; (Z:n:) treats
  newlines as ordinary whitespace (the default is to turn unquoted
  newlines into semicolons; this is now documented).

- The parameter subscript flag (e) forces the argument to be treated
  as a string, never a pattern, e.g. ${array[(ie)*]} looks for the
  index of the array element containing the literal string "*".

- The operators :| and :* in parameter substitution allow for array
  subtraction and intersection in the form ${name:|array}. With the :|
  operator, all entries in $name that are also in $array will be removed
  from the substitution. Conversely for the :* operation only the
  entries that are in both arrays will be substituted.

- Numeric expansions can have a positive or negative step
  e.g. "{3..9..2}".  Negative start and end of ranges are also now
  supported.

- =(<<<...) is optimised to eliminate the need for an external process.
  It writes the given string to a file and substitutes the name on the
  command line.

- The redirection operations "{myfd}>file" and "{myfd}>&-" open and
  close a new file descriptor (at least 10) contained in the shell
  variable myfd, which can be written to with ">&$myfd".  This allows
  arbitrary file descriptors rather than the explicit range 0 to 9.

- New prompt escapes:
  %x and %I show source file and line number, useful in $PS4 (the
    existing %N and %i show names and lines in the execution environment
    rather than the source file).
  %F, %K, %f, %k allow colouring of prompts both using ANSI colour names
    and values supported by individual terminal emulators.

Builtins and shell functions
-+-+-+-+-+-+-+-+-+-+-+-+-+-+

- Directory-changing builtins take an option -q to suppress side
  effects such as printing directories or calling the chpwd hook functions.

- Various enhancements have been made to traps:
  - The option DEBUG_BEFORE_CMD is on by default, so DEBUG traps
    can be used to debug code about to be run
  - $ZSH_DEBUG_CMD in such a trap gives the code to be run
  - "setopt ERR_EXIT" in a DEBUG trap causes the code not to be executed

- The "fc" builtin is now more useful non-interactively.

Shell variables (parameters)
-+-+-+-+-+-+-+-+-+-+-+-+-+-+

- New variables:
  CORRECT_IGNORE can be set to a pattern to be ignored in spelling correction.
  KEYBOARD_HACK defines characters to be ignored if typed unmatched at
    the end of the line (an extension of the SUN_KEYBOARD_HACK option,
    but note that setting the option will override the variable).
  ZSH_PATCHLEVEL provides a unique indication of the code compiled to
    make the shell, even between releases.
  ZSH_SUBSHELL indicates the subshell level, incremented once per fork, at
    which the code is being run.

Options
-+-+-+-

- New options:
  COMBINING_CHARS: assume that the terminal displays combining
    characters correctly.  The shell cannot determine this by itself,
    hence the option.  This is highly recommended for MacOS X where
    file names are stored with accented characters split into basic
    and combining characters.
  DEBUG_BEFORE_CMD (on by default): execute debug traps before the
    code they refer to.  This is a change of the default behaviour
    as the new behaviour is much more useful.
  HASH_EXECUTABLES_ONLY: don't insert non-executable files into the
    command hash used e.g. by completion; this is optional as the
    resulting behaviour may be very slow on network paths.
  HIST_FCNTL_LOCK: Use the system's file locking mechanism instead
    of an ad-hoc mechanism for locking history files.
  HIST_LEX_WORDS: Perform lexical analysis on history lines read from
    files, so the words are more accurately determined.  May be very slow.
  HIST_SAVE_BY_COPY (on by default): if unset, write a history file in
    place by truncating the old one.  Only needs to be turned off in
    special circumstances.
  MULTIBYTE (on by default if available): both variables and editor
    command lines are treated as sequences of multibyte characters
    rather than raw bytes depending on the locale.  May be turned off
    within functions to perform bytewise operations.
  MULTI_FUNCDEF (on by default): "foo bar () { ... }" defines two
    functions.  This is often found to be confusing and bug-prone,
    so you may want to unset it.
  PATH_SCRIPT: search the path for a script specified as the first
    argument to the shell on invocation.
  POSIX_ALIASES: reserved words are not candidates for alias expansion.
  POSIX_CD: make directory changing more POSIX-compatible.
  POSIX_JOBS: make job control more POSIX compliant.
  POSIX_STRINGS: $'...\0...' always processes \0 as a NULL, but if the
    option is set the remainder of the string is ignored.
  POSIX_TRAPS: EXIT traps are not executed on return from shell functions.
  PROMPT_SP: improves display of lines not ending with newlines when
    PROMPT_CR is in effect.
  SOURCE_TRACE: print information as files are executed with ".",
    "source", or as startup or shutdown files.

Line editor
-+-+-+-+-+-

- Supports multibyte characters, including characters wider than one
  screen cell and (with the COMBINING_CHARS option) combining characters.

- New builtin widgets:
  arguments-base: allow non-decimal numeric arguments
  history-incremental-pattern-search-{backward,forward}: support
    patterns in incremental searches.

- New special variables:
  region_highlight allows arbitrary highlighting of parts of the
    command line; it is maintained dynamically.
  UNDO_CHANGE_NO gives a unique record of the current change state of
    the command line, for undoing back to a particular point using
    the undo widget.
  zle_highlight provides master control of highlighting for special
    modes, e.g. unprintable characters.
  ZLE_LINE_ABORTED records an editor line that was aborted by an error
    or C-g.  It can be used to recover aborted lines.
  ZLE_STATE give miscellaneous information, currently whether the line
    editor is in insert or overwrite mode.

- The undo widget takes an argument, a previous value of $UNDO_CHANGE_NO.

Completion
-+-+-+-+-+

- Many new and enhanced completion functions

- New styles:
  accept-exact-dirs:  suppress path expansion of directory components
    that already exist, speeding up completion significantly on slow
    network directories.
  path-completion:  can be used to suppress directory components before
    the current one completely, so e.g. /u/b<TAB> only completes after the
    "b", not the "u".

- New special variables:
  ZLE_REMOVE_SUFFIX_CHARS, ZLE_SPACE_SUFFIX_CHARS provide enhanced
    flexibility over suffix removal.

- Matching control, typically handled with the matcher-list style,
  supports named character ranges, such as [:upper:], wherever
  ranges were allowed, for example 'm:{[:upper:]}={[:lower:]}'.
  However, matching control does not yet handle multibyte characters
  properly, so this is currently limited to ASCII.

Syntax and compatibility
-+-+-+-+-+-+-+-+-+-+-+-+

- Substitutions of the form ${var:-"$@"} and ${var:+"$@"} now behave
  much more like other shells when appropriate (e.g. with the
  SH_WORD_SPLIT option).

- Assignments within variable substitutions, such as ${var=value},
  are also more compatible with other shells where appropriate.

- The emulate command can now be passed an expression to be evaluated
  in a "sticky" emulation, so that functions defined there always
  behave in the appropriate emulation.

- "emulate sh" and similar modes have improved compatibility with
  respect to deciding whether the shell should exit on errors.

- Signals now accept SIG as part of the name.

Modules
-+-+-+-

- Modules now present "features", specific builtins (b:), parameters
  (p:), conditions (c:) and math functions (f:), allowing more control
  over what is imported from a module.

- The zsh/curses module provides access to the "curses" screen
  manipulation package.

- The zsh/datetime module has a calendar utility, although it is not
  as robust as standalone calendar utilities.

- The zsh/newuser module and associated functions has facilities for
  setting up startup files for a first-time user.

- The zsh/parameter module contains some new arrays to aid in tracing
  of the shell's call stack: $funcsourcetrace and $funcfiletrace.

- The zsh/parameter module provides $usergroups, an associative arrays
  whose keys are the names of groups the current user belongs to, with
  the group identifier as the corresponding value.

- The zsh/system module has a zsystem builtin which provides file
  locking and also a forward-compatible means for testing subcommands
  supported.

Internal improvements
-+-+-+-+-+-+-+-+-+-+-

- High resolution timestamps are used internally for certain
  comparisons when available.

Add-on functions
-+-+-+-+-+-+-+-+

- The VCS_Info system provides a way of keeping track of the state
  of numerous version control systems within the shell.

- cdr etc.: change to a directory from a list that persists between
  shell instances, with completion support.

- regexp-replace replaces text in variables using regular expressions;
  it may be used by zle function widgets based on the functions
  replace-string and replace-string-again to provide regular expression
  replacements in the line editor.


Changes in 4.2 since version 4.2.0
----------------------------------

- The autoload and related builtins take options -k and -z to indicate
  ksh or zsh autoloading style for given functions, making it possible
  to mix and match.

- Assignments to associative arrays can use the i and r index flags.
  For example,
    assoc[(i)alpha*]=bravo
  sets the value for the element whose key matches the pattern `alpha*';
    assoc[(r)activ*]=passive
  sets the value for the element whose current value matches the pattern
  `activ*'.

- The glob qualifier F indicates a non-empty directory.  Hence *(F)
  indicates all subdirectories with entries, *(/^F) means all
  subdirectories with no entries.

- fc -p and fc -P provide push/pop for the status of the shell's
  history (both internal and using the history file).  With automatic
  scoping (fc -ap) it becomes easy to use a temporary history in a
  function.  This has been added to the calculator function zcalc to make
  its internal history work more seamlessly.

- A new `try block' and `always block' syntax has been introduced
  to make it easier to ensure the shell runs important tidy-up code
  in the event of an error.  It also runs after a break, continue, or
  return, including a return forced by the ERR_RETURN option
  (but not an exit, which is immediate).  The syntax is:
    `{' try-block-list `}' `always' `{' always-block-list `}'
  where no newline or semicolon may appear between `}' and `always'.
  This is compatible with all previous valid zsh syntax as an `always'
  at that point used to be a syntax error.  For example,
    { echo Code run in current shell } always { echo Tidy-up code }

- A new zle widget reset-prompt has been added to re-expand the current
  prompt.  Changes to the variable in use as well as changes in its
  expansions are both taken into account.  The same effect is now forced by
  a job change notification, making the %j prompt escape and %(j..) ternary
  expression more useful.

- The zftp module supports ports following the hostname in the normal suffix
  notation, `host:port'.  This requires IPv6 colon-style addresses to be
  specified in suitably quoted square brackets, for example:

  zftp open '[f000::baaa]'
  zftp open '[f000::baaa]:ftp'

  (the two are equivalent).

- Special traps, those that don't correspond to signals, i.e. ZERR, DEBUG
  and EXIT are no longer executed inside other traps.  This caused
  unnecessary confusion if, for example, both DEBUG and EXIT traps
  were set.  The new behaviour is more compatible with other shells.

- New option TRAPS_ASYNC which if set allows traps to run while the
  shell is waiting for a child process.  This is the traditional zsh
  behaviour; POSIX requires the option to be unset.  In sh/ksh
  compatibility mode the option is turned off by default and the option
  letter -T turns it on, for compatibility with FreeBSD sh.

- New WIDGETSTYLE, WIDGETFUNC parameters in ZLE.

- Glob qualifier (+func) is shorthand for (e:func:) (calls a command,
  typically a shell function, with no argument).


New features between zsh versions 4.0 and 4.2
---------------------------------------------

Configuration:
- upgraded to use autoconf post-2.50
- improved compatibility with other shells through shell options,
  builtin arguments and improved builtin option parsing

Syntax and builtins:
- new printf builtin
- `+=' to append to parameters which works for scalars, arrays and (with
  pairs) associative arrays.
- enhanced multiple parameter `for' loops:
    for key value in key1 value1 key2 value2 ...
  maintaining full compatibility with POSIX syntax.
- Suffix aliases allow the shell to run a command on a file by suffix,
  e.g `alias -s ps=gv' makes `foo.ps' execute `gv foo.ps'.  Supplied
  function zsh-mime-setup uses existing mailcap and mime.types files
  to set up suitable aliases.  Supplied function pick-web-browser is
  suitable for finding a browser to show .html etc. files by suffix alias.
- new option `no_case_glob' for case-insensitive globbing.

Add-on modules and functions:
- zsh/datetime modules makes date formatting and seconds since EPOCH
  available inside the shell.
- zsh/net/tcp module provides builtin interface to TCP through ztcp
  builtin.  Function suite for interactive and script use with expect-style
  pattern matching.
- zsh/net/socket module provides zsocket builtin.
- zcalc calculator function with full line editing.
- builtin interface to pcre library
- zsh/zselect module pro