CVE-2021-45444: ZSH - Release Notes

Changes between 5.8 and 5.8.1****Incompatibilities

• PROMPT_SUBST expansion is no longer performed on arguments to prompt-expansion sequences such as %F.

Changes

• CVE-2021-45444: Some prompt expansion sequences, such as %F, support ‘arguments’ which are themselves expanded in case they contain colour values, etc. This additional expansion would trigger PROMPT_SUBST evaluation, if enabled. This could be abused to execute code the user didn’t expect. e.g., given a certain prompt configuration, an attacker could trick a user into executing arbitrary code by having them check out a Git branch with a specially crafted name.

  This is fixed in the shell itself by no longer performing PROMPT_SUBST evaluation on these prompt-expansion arguments.

  Users who are concerned about an exploit but unable to update their binaries may apply the partial work-around described in the file Etc/CVE-2021-45444-VCS_Info-workaround.patch included with the shell source. [ Reported by RyotaK. Additional thanks to Marc Cornellà. ]

Changes between 5.7 and 5.8****Incompatibilities

• The history expansion !:1:t2 used to be interpreted such that the 2 was a separate character added after the history expansion. Now it is an argument to the :t modifier. The behaviour of :h has similarly changed.
• The vcs_info function VCS_INFO_quilt-dirfind now returns a string value by setting $REPLY. Previously it printed the value to standard output.
• The cd and chdir builtins no longer interpret operands like -1 and +2 as stack entries when POSIX_CD is enabled.
• Dropping privileges with `unsetopt privileged` may fail (with an error message) on some older and uncommon platforms due to library dependency changes made in the course of fixing CVE-2019-20044 (see below). Please report this to the zsh-workers mailing list if your system is affected.

Changes

• CVE-2019-20044: When unsetting the PRIVILEGED option, the shell sets its effective user and group IDs to match their respective real IDs. On some platforms (including Linux and macOS, but not FreeBSD), when the RUID and EUID were both non-zero, it was possible to regain the shell’s former privileges by e.g. assigning to the EUID or EGID parameter. In the course of investigating this issue, it was also found that the setopt built-in did not correctly report errors when unsetting the option, which prevented users from handling them as the documentation recommended. setopt now returns non-zero if it is unable to safely drop privileges. [ Reported by Sam Foxman. ]
• The zsh/zutil module’s zparseopts builtin learnt an -F option to abort parsing when an unrecognised option-like parameter is encountered.
• The zsh/files module gained a chmod builtin.
• Several changes have been made to the way completion functions track ‘precommands’ (such as `command` and `env`) and determine whether the command being completed for is a shell builtin. Developers of completion functions may wish to familiarise themselves with `_normal -p` and `_pick_variant -b`.
• The option CD_SILENT was added to suppress all output from cd (whether explicit or implicit with AUTO_CD). It is disabled by default.
• The compadd builtin’s -o option now takes an optional argument to specify the order of completion matches. This affects the display of candidate matches and the order in which they are selected when cycling between them using menu completion.
• The :h and :t modifiers in parameter expansion (if braces are present), glob qualifiers and history expansion may take following decimal digit arguments in order to keep that many leading or trailing path components instead of the defaults of all but one (:h) and one (:t). In an absolute path the leading ‘/’ counts as one component.
• The functions builtin gained a -c option to efficiently copy functions.
• The zshmisc(1) manual page incorrectly stated that when ‘exit’ is used in a `try’ block inside a function, the corresponding `always’ block will be executed. The manual page has been corrected. The shell’s behaviour has not changed.

Changes between 5.6.2 and 5.7****Incompatibilities

• vcs_info git: The gen-unapplied-string hook receives the patches in order (next to be applied first). This is consistent with the hg backend and with one of two contradictory claims in the documentation (the other one has been corrected). In zsh through 5.6.2, the patches were passed in reverse order, next to be applied being last in the array. The gen-applied-string hook is unaffected; it still receives the patches in reverse order, from last applied to first applied.
• The option NO_UNSET now also applies when reading values from variables without a preceding ‘$’ sign in shell arithmetic expansion and in the double-parentheses and ‘let’ arithmetic commands.

Changes

• Support for 24-bit true color terminals has been added. Hex triplets can be used when specifying colours for prompts and line editor highlighting. On 88 and 256 colour terminals, a new zsh/nearcolor module allows colours specified with hex triplets to be matched against the nearest available colour.
• The zsh/datetime module’s strftime builtin now accepts an argument specifying the nanoseconds time component; both arguments can be omitted to use the current time.

Changes between 5.5.1 and 5.6.2****Incompatibilities

• The completion helper _remote_files, typically used after a hostname with scp-style completion, now uses remote-files instead of files as a tag. This makes it easier to restrict completions with the tag-order style.

Changes

• CVE-2018-0502: Data from the second line of a #! script file might be passed to execve(). For example, in the following situation -

  printf ‘#!foo\nbar’ > baz ./baz

  the shell might take “bar” rather than “foo” for the argv[0] to be passed to execve(). [ Reported by Anthony Sottile and Buck Evan. ]

• CVE-2018-13259: A shebang line longer than 64 characters would be truncated. For example, in the following situation:

  ( printf '#!’; repeat 64 printf 'x’; printf ‘y’ ) > foo ./foo

  the shell might execute x…x (64 repetitions) rather than x…xy (64 x’s, one y). [ Reported by Daniel Shahaf. ]

• Non-stop IEEE 754 arithmetic support - Inf and NaN are now returned from floating point operations where errors were printed before. Inf and NaN are also recognised in arithmetic expressions.

• In shell patterns, [[:blank:]] now honours the locale instead of matching exclusively on space and tab, like for the other POSIX character classes or for extended regular expressions.

• The zsh/system module now provides the PID of the last process substitution via $sysparams[procsubstpid].

• Time formatting via the %D prompt escape now offers nanosecond precision with the %. and %N format specifiers. Additionally, nanosecond precision on file times is supported in the module zsh/stat.

• The zsh/mathfunc module now includes a log2() function.

• The parameter ZLE_RECURSIVE has been added to indicate the current ZLE recursion level.

Changes between versions 5.5 and 5.5.1Apart from a fix for a configuration problem finding signal names from (some) recent versions of glibc, there are only minor changes.Changes between versions 5.4.2 and 5.5****Incompatibilities

• The default build-time maximum nested function depth has been decreased from 1000 to 500 based on user experience. However, it can now be changed at run time via the variable FUNCNEST. If you previously configured the shell to set a different value, or to remove the check, this is now reflected in the default value of the variable.

• The syntax

  foo=([key]=value)

  can be used to set elements of arrays and associative arrays. In the unlikely event that you need to set an array by matching files using a pattern that starts with a character range followed by '=’, you need to quote the '=’, e.g.:

  foo=([aeiou]\=vowel)

  This is only required for array values contained within parentheses; command line expansion for normal arguments has not changed.

• The syntax

  [[ -o foo ]]

  where foo is not the name of a shell option (with optional underscores and optional “no” prefix) used to be treated as a syntax error, i.e., the enclosing command line or file were aborted. It now emits a warning and returns a non-zero exit code. For further details, see the documentation of the -o switch in the chapter “Conditional Expressions” in the zshmisc(1) manual.

Changes

• The effect of the NO_INTERACTIVE_COMMENTS option extends into $(…) and `…` command substitutions when used on the command line. Previously, comments were always recognized within command substitutions unless the comment character “#” was disabled via reset of $histchars.

An alternative assignment syntax for indicating indices for arrays and keys for associative arrays:

typeset -a array=([1]=first [2]=second) typeset -A assoc=([key1]=val1 [key2]=val2)

is allowed for compatibility with other shells. In the case of normal arrays the new syntax can be mixed with the old.

Changes between versions 5.3.1 and 5.4.1****Incompatibilities

• The default behaviour of code like the following has changed:

  alias foo=’noglob foo’ foo() { print function body; }

  When this is encountered in a start-up file, or other place where input was read line by line, “foo” is in command position and is expanded as an alias before the function definition takes place. In previous versions of the shell, this caused two functions “noglob” and “foo” to be defined. Any expansion of an alias in a function definition is nearly always an unintended effect, as well as hard to detect, so has been made an error. (The option setting NO_MULTI_FUNC_DEF turned this case into an error, but did not help with other cases and is off by default.) The alternative, of not expanding the alias, was rejected as it was more difficult to achieve in the parser and also would silently change the shell’s behaviur between versions. A new option, ALIAS_FUNC_DEF, has been added, which can be set to make the shell behave as in previous versions. It is in any case recommended to use the “function” keyword, as aliases are not expanded afterwards.

• It was an undocumented, and largely useless, feature that a function autoloaded with an absolute path was searched for along the normal fpath (as if the leading / was missing) and, if found, loaded under the full name including the leading slash. This has been replaced with the more useful feature that the function is searched for only at the given absolute path; the name of the function is the base name of the file. Note that functions including a non-leading / behave as before, e.g. if `dir/name’ is found anywhere under a directory in $fpath it is loaded as a function named `dir/name’.

• vcs_info: When neither a set-patch-format nor a gen-applied-string (resp. gen-unapplied-string) hook is set, vcs_info now ‘%’-escapes the applied-string (resp. unapplied-string) before interpolating it into the patch-format string, to prevent literal `%’ signs in the interpolated value from being interpreted as prompt escape sequences. If you use ${vcs_info_msg_0_} in a context other than the shell prompt, you may need to undo the escaping with:

  print -v vcs\_info\_msg\_0\_ -Pr -- "${vcs\_info\_msg\_0\_}"
  

  This is also needed if $vcs_info_msg_0_ is used to set $psvar.

• functions executed by ZLE widgets no longer have their standard input closed, but redirected from /dev/null instead. That still guards against user defined widgets inadvertently reading from the tty device, and addresses the antisocial behaviour of running a command with its stdin closed.

Changes

• The ‘exec’ and ‘command’ precommand modifiers, and options to them, are now parsed after parameter expansion. Previously, both the modifier and any options to it were parsed between alias expansion and parameter expansion (see zshexpn(1)), so they could neither be quoted nor be the result of parameter expansion. Examples: ‘s=command; $s -V ls’ and ‘\command -V ls’ now work as expected.
• Functions executed by ZLE widgets no longer have their standard input closed, but redirected from /dev/null instead. That still guards against user defined widgets inadvertently reading from the tty device.
• There is an option WARN_NESTED_VAR, a companion to the existing WARN_CREATE_GLOBAL that causes a warning if a function updates a variable from an enclosing scope without using typeset -g. It can be turned on for an individual function with "functions -W".
• zmodload now has an option -s to be silent on a failure to find a module but still print other errors.

Changes between versions 5.3 and 5.3.1

• Fix handling of "printf -" and "printf --".
• Minor completion fixes for FreeBSD (sysctl, chflags).

Changes between versions 5.2 and 5.3****Incompatibilities

• In character classes delimited by "[" and "]" within patterns, whether used for filename generation (globbing) or other forms of pattern matching, it used not to be possible to quote "-" when used for a range, or “^” and “!” when used for negating a character set. The characters can now be quoted by any of the standard shell means, but note that the "[" and "]" must not be quoted. For example,

  [[ $a = [‘a-z’] ]]

  matches if the variable a contains just one of the characters "a", "-" or “z” only. Previously this would have matched any lower case ASCII letter. Note therefore the useful fact that

  [[ $a = [“$cset”] ]]

  matches any character contained in the variable "cset". A consequence of this change is that variables that should have active ranges need (with default zsh options) to be indicated explicitly, e.g.

  cset="a-z" [[ b = [${~cset}] ]]

  The “~” causes the "-" character to be active. In sh emulation the “~” is unncessary in this example and double quotes must be used to suppress the range behaviour of the "-".

• The first argument to ‘repeat’ is now evaluated as an arithmetic expression. It was always documented to be an arithmetic expression, but until now the decimal integer at the start of the value was used and the remainder of the value discarded. This could lead to different behaviour if the argument contains non-numeric characters, or if the argument has leading zeroes and the OCTAL_ZEROES option is set.

• For some time the shell has had a POSIX_TRAPS option which determines whether the EXIT trap has POSIX behaviour (the trap is only run at shell exit) or traditional zsh behaviour (the trap is run once and discarded when the enclosing fuction or shell exits, whichever happens first). The use of this option has now been made “sticky” on the EXIT trap — in other words, the setting of the option at the point where the trap is set now determines whether the trap has POSIX or traditional zsh behaviour. This means that changing the option after the trap was set no longer has any effect.

  Other aspects of EXIT trap handling have not changed — there is still only one EXIT trap at any point in a programme, so it is not generally useful to combine POSIX and non-POSIX behaviour in the same script.

• There was an undocumented feature dating from the early days of zsh that glob qualifiers consisting only of the digits 0 to 7 were treated as an octal file mode to “and” with the modes of files being tested. This has been removed in order to be more sensitive to syntax errors. The “f” qualifier has for many years been the documented way of testing file modes; it allows the “and” test ("*(f+1)" is the documented equivalent of "*(1)") as well as many other forms.

• The completion helper function _arguments now escapes both backslashes and colons in the values of option arguments when populating the $opt_args associative array. Previously, colons were escaped with a backslash but backslashes were not themselves escaped with a backslash, which lead to ambiguity: '-x foo\:bar’ (one argument with a backslashed colon) and '-x foo\\ bar’ (two arguments, and the first one ends in a backslash) would both set $opt_args[-x] to the same value. This example assumes the -x option’s spec declared two arguments, as in:

  \_arguments : -x:foo:${action}:bar:$action
  

  For the more common case of non-repeatable options that take a single argument, completion functions now have to unescape not only colons but also backslashes when obtaining the option’s argument from $opt_args.

• Previously, if the function command_not_found_handler was run in place of a command-not-found error, and the function returned non-zero status, zsh set the status to 127 and printed an error message anyway. Now, the status from the handler is retained and no additional message is printed. The main reasons for this change are that it was not possible to return a non-zero status to the parent shell from a command executed as a replacement, and the new implementation is more consistent with other shells.

• The output of “typeset -p” (and synonyms) now takes into account the function scope and export state of each parameter. Exported parameters are output as “export” commands unless the parameter is also local, and other parameters not local to the scope are output with the "-g" option. Previously, only “typeset” commands were output, never using "-g".

• At spelling-correction prompt ($SPROMPT), where the choices offered are [nyae], previously <Enter> would be accepted to mean [N] and <Space> and <Tab> would be accepted to mean [Y]. Now <Space> and <Tab> are invalid choices: typing either of them remains at the prompt.

• The $ary[i,j] subscript syntax to take a slice of an array behaves differently when both i and j are larger than the number of elements in the array. When i == j, such a slice always yields an empty array, and when i < j it always yields an array of one empty string element. The following example illustrates how this differs from past versions.

   nargs() { print $# }
   a=(one two)
   for i in 1 2 3 4; do
    for j in 1 2 3 4 5; do
     print -n "$i $j => "
     nargs "${(@)a\[i,j\]}"
    done
   done
   
   5.2       |  5.3 \*\*
   ----------+----------
   1 1 => 1  |  1 1 => 1
   1 2 => 2  |  1 2 => 2
   1 3 => 2  |  1 3 => 2
   1 4 => 2  |  1 4 => 2
   1 5 => 2  |  1 5 => 2
   2 1 => 0  |  2 1 => 0
   2 2 => 1  |  2 2 => 1
   2 3 => 1  |  2 3 => 1
   2 4 => 1  |  2 4 => 1
   2 5 => 1  |  2 5 => 1
   3 1 => 0  |  3 1 => 0
   3 2 => 0  |  3 2 => 0
   3 3 => 0  |  3 3 => 0
   3 4 => 0  |  3 4 => 1   \*\*
   3 5 => 0  |  3 5 => 1   \*\*
   4 1 => 0  |  4 1 => 0
   4 2 => 0  |  4 2 => 0
   4 3 => 0  |  4 3 => 0
   4 4 => 1  |  4 4 => 0   \*\*
   4 5 => 1  |  4 5 => 1
  

Changes

• It is possible to enable character width support for Unicode 9 by configuring with `–enable-unicode9’; this compiles in some additional tables. At some point this support may move into a module, in which case the configure option will be changed to cause the module to be permanently loaded. This option is not useful unless your terminal also supports Unicode 9.
• The new word modifier ‘:P’ computes the physical path of the argument. It is different from the existing ‘:a’ modifier which always resolves ‘/before/here/…/after’ to '/before/after’, and differs from the existing ‘:A’ modifier which resolves symlinks only after ‘here/…’ is removed, even when /before/here is itself a symbolic link. It is recommended to review uses of ‘:A’ and, if appropriate, convert them to ‘:P’ as soon as compatibility with 5.2 is no longer a requirement.
• The output of “typeset -p” uses “export” commands or the "-g" option for parameters that are not local to the current scope. Previously, all output was in the form of “typeset” commands, never using "-g".
• vi-repeat-change can repeat user-defined widgets if the widget calls zle -f vichange.
• The parameter $registers now makes the contents of vi register buffers available to user-defined widgets.
• New vi-up-case and vi-down-case builtin widgets bound to gU/gu (or U/u in visual mode) for doing case conversion.
• A new select-word-match function provides vim-style text objects with configurable word boundaries using the existing match-words-by-style mechanism.
• Support for the conditional expression [[ -v var ]] to test if a variable is set for compatibility with other shells.
• The print and printf builtins have a new option -v to assign the output to a variable. This is for bash compatibility but with the additional feature that, for an array, a separate element is used each time the format is reused.
• New x: syntax in completion match specifications make it possible to disable match specifications hardcoded in completion functions.

Changes between versions 5.1.1 and 5.2****Incompatibilities

The behaviour of the parameter flag § has changed when it appears in a nested parameter group, in order to make it more useful in such cases. A § in the outermost parameter group behaves as before.

Changes

• The new module zsh/param/private can be loaded to allow the shell to define parameters that are private to a function scope (i.e. are not propagated to nested functions called within this function).

• The parameter flag ${§…} is now more useful when it appears in a nested expansion. For example,

  typeset -A assoc=(one un two deux three trois) name=assoc print ${${§name}[one]}

  now prints "un". In previous versions of the shell the value of the substitution was fully expanded on return from ${§name}, making associative array subscripting difficult. As a side effect, flags for formatting appearing in the inner substitution now affect the substitution of the name (into “assoc” in this case), which is not normally useful: flags that should apply to the value must be in the outer substitution.

• The GLOB_STAR_SHORT option allows the pattern **/* to be shortened to just ** if no / follows. so **.c searches recursively for a file whose name has the suffix ".c".

• The effect of the WARN_CREATE_GLOBAL option has been significantly extended, so expect it to cause additional warning messages about parameters created globally within function scope.

Changes between versions 5.1 and 5.1.1

• The ZLE variables YANK_ACTIVE, YANK_START and YANK_END have been added and are useful for managing highlighting.
• The zsh-specific pattern match range tests have been supplemented with [:INCOMPLETE:] and [:INVALID:] to help detect the state of partially read multibyte character strings.

Changes between versions 5.0.8 and 5.1

The builtins declare, export, local, readonly and typeset now have corresponding reserved words. When used in this form, the builtin syntax is extended so that assignments following the reserved word are treated similarly to assignments that appear at the start of the command line. For example,

local scalar=`echo one word` array=(several words)

creates a local “scalar” containing the text “one word” and an array “array” containing the words “several” "words".

• The print builtin has new options -x and -X to expand tabs.
• Several new command completions and numerous updates to others.
• Options to “fc” to segregate internal and shared history.
• All emulations including “sh” use multibyte by default; several repairs to multibyte handling.
• ZLE supports “bracketed paste” mode to avoid interpreting pasted newlines as accept-line. Pastes can be highlighted for visibility and to make it more obvious whether accept-line has occurred.
• Improved (though still not perfect) POSIX compatibility for getopts builtin when POSIX_BUILTINS is set.
• New setopt APPEND_CREATE for POSIX-compatible NO_CLOBBER behavior.
• Completion of date values now displays in a calendar format when the complist module is available. Controllable by zstyle.
• New parameter UNDO_LIMIT_NO for more control over ZLE undo repeat.
• Several repairs/improvements to the contributed narrow-to-region ZLE function.
• Many changes to child-process and signal handling to eliminate race conditions and avoid deadlocks on descriptor and memory management.
• New builtin sysopen in zsh/system module for detailed control of file descriptor modes.

Changes between versions 5.0.7 and 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.

• The option FORCE_FLOAT now forces variables, not just constants, to floating point in arithmetic expressions.

• The type of an assignment in arithmetic expressions, e.g. the type seen by the variable res in $(( res = a = b )), is now more logical and C-like.

• The default binding of ‘u’ in vi command mode has changed to undo multiple changes when invoked repeatedly. ‘^R’ is now bound to redo changes. To revert to toggling of the last edit use:

  bindkey -a u vi-undo-change
  

• Compatibility with Vim has been improved for vi editing mode. Most notably, Vim style text objects are supported and the region can be manipulated with vi commands in the same manner as Vim’s visual mode.

• 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 between versions 5.0.6 and 5.0.7

• Contains a security fix to disallow evaluation of the initial values of integer variables imported from the environment (they are instead treated as literal numbers). That could allow local privilege escalation, under some specific and atypical conditions where zsh is being invoked in privilege elevation contexts when the environment has not been properly sanitized, such as when zsh is invoked by sudo on systems where “env_reset” has been disabled.
• The default $fpath/$FPATH is now designed always to include /usr/local/share/zsh/site-functions. 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", no matter how the shell was configured.
• 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.
• 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 versions 5.0.5 and 5.0.6****Incompatibilities

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.

Changes

• 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).
• Another new prompt feature is the %. escape within time strings, for example %D{%H:%M:%S.%.}. It provides zero-padded decimal fractions of 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.

Changes between versions 5.0.2 and 5.0.5Releases 5.0.3 and 5.0.4 were replaced with 5.0.5 because they contained serious bugs.Incompatibilities

The “zshaddhistory” hook mechanism documented in the zshmisc manual page has been upgraded so that a hook returning status 2 causes a history line to be saved on the internal history list but not written to the history file. Previously any non-zero status return would cause the line not to be saved on the history at all. It is recommended to use status 1 for this (indeed most shell users would naturally do so).

Changes

• 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.
• 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.
• 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 between 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.

Changes between versions 5.0.1 and 5.0.2

• Bug fix for anonymous functions.

Changes between versions 5.0.0 and 5.0.1****Incompatibilities

In 5.0.0, the new “sticky” emulation feature was applied to functions explicitly declared within an expression following `emulate … -c’, but did not apply to functions marked for autoload in that expression. This was not documented and experience suggests it was inconvenient, so in 5.0.2 autoloads also have the sticky property.

In other words,

emulate zsh -c ‘func() { … }’

behaves the same way in 5.0.0 and 5.0.2, with the function func always being run in native zsh emulation regardless of the current option settings. However,

emulate zsh -c ‘autoload -Uz func’

behaves differently: in 5.0.0, func was loaded with the options in effect at the point where it was first run, and subsequently run with whatever options were in effect at that point; in 5.0.2, func is loaded with native zsh emulation options and run with those same options. This is now the recommended way of ensuring a function is loaded and run with a consistent set of options.

Note that the command `autoload -z’ has never affected the options applied when the function is loaded or run, only the effect of the KSH_AUTOLOAD option at the point the function is loaded.

Changes

• 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.
• “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.
• 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 possibly 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.

New features between zsh versions 4.2 and 5.0(Note: Most of these changes are already included in 4.3.17.)

• 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 compatibility 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 ® 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 characters 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 between versions 4.3.16 and 4.3.17

Complete fixes from last release.

Changes between versions 4.3.15 and 4.3.16

The option HASH_EXECUTABLES_ONLY has been added. When this is set, directories in the command path will be checked for executables before they are added to the command table (hash); otherwise, all files in the directory are added. The effect of this option was present in 4.3.15, which could cause significant delays when hashing on systems with network directories in the path.

The shell emulation mode was improved for more bash-like behavior. The bash completion support was also improved.

New completions for sqlite, vcsh and xclip.

Changes between versions 4.3.14 and 4.3.15

Fix a POSIX compatibility related bug which might cause a subshell to hang.

Changes between versions 4.3.13 and 4.3.14

Bug fixes in code and test suite.

Changes between versions 4.3.12 and 4.3.13

There are no significant feature changes to the shell itself, although many bug fixes and improvements to functions.

Changes between versions 4.3.11 and 4.3.12

The zsh/parameter module has a new readonly associative array $usergroups whose keys are the names of system groups of which the current user is a member and whose values are the corresponding group identifiers.

The region_highlight array, which controls highlighting of the command line from zle widgets, is now updated dynamically as the command line is edited.

In POSIX emulation (“emulate sh”) the shell is more accurate about when it should or should not exit on errors.

The ${NAME:OFFSET:LENGTH} syntax now supports negative LENGTH, which counts back from the end of the string.

The (g:opts:) flag in parameter expansion processes escape sequences like the echo and print builtins. opts can be any combination of o, e and c. With e, acts like print rather than echo except for octal escapes which are controlled separately by the o option. With c, interpret control sequences like “^X” as bindkey does. Regardless of the opts, \c is not interpreted.

Changes between versions 4.3.10 and 4.3.11

Note also the list of incompatibilities in the README file.

When the shell is invoked with the base name of a script, for example as `zsh scriptname’, previous versions of zsh have used the name directly, whereas other shells use the value of $PATH to find the script. The option PATH_SCRIPT has been added to provide the alternative behaviour. This is turned on where appropriate in compatibility modes.

Parameters, globbing, etc.

Parameter expansion has been enhanced to provide the ${NAME:OFFSET} and ${NAME:OFFSET:LENGTH} syntax for substrings and subarrays present in several other shells. OFFSET always uses zero-based indexing. The only clash with existing zsh syntax occurs if OFFSET begins with an alphabetic character or `&’, which is not likely.

The (D) flag in parameter expansion abbreviates directories in the substituted value. The (q-) flag does minimal shell quotation of arguments for maximum human readability of the result.

The (Z) flag in parameter expansion is an enhanced version of the (z) flag that takes an argument indicating how the string to be split is treated. (Z:c:) parses comments as strings; (Z:C:) parses comments and strips them; (Z:n:) treats newlines as ordinary whitespace: (z) has always treated unquoted newlines as shell delimiters and turned them into semicolons, though this was not previously documented.

Numeric expansion with braces has been extended so that a step may be given, as in {3…9…2}. The step may be negative as may the start and end of the range (this is also new).

The glob qualifier P can be used to add a separate word before each match. For example, *(P:-f:) produces the command line `-f file1 -f file2 …’.

Regular expression matches now use the same variables for storing matched components as shell pattern matching. The function system now provides the function regexp-replace for replacing text using regular expressions. The zle widget functions replace-string, replace-string-again, if defined with regex in the name (e.g. “zle -N replace-regexp replace-string”), perform regular expression matches. In replacement text \& and \1 have the standard meaning.

Line editor and completion

The completion system now has a style path-completion. Setting this to false inhibits completion of paths before the current path component, e.g. /u/b/z no longer completes to /usr/bin/zsh. This is useful on systems where this form of completion is pathologically slow due to network performance.

With the MULTIBYTE option, the line editor now highlights bytes in the input that are not part of a valid character in the current locale in hex as <XX> for hex digits X; highlighting is controlled by the “special” keyword in the zle_highlight array. These can be distinguished from unprintable Unicode characters which also use “special” highlighting as the latter are always two or four bytes long, e.g. <XXXX>, <XXXXXXXX>.

zle_highlight also controls highlighting of a removable completion suffix, e.g. the “/” automatically appended to directories. This uses the keyword "suffix".

The line editor now sets the variable ZLE_LINE_ABORTED if there is an error when editing the line. The following code can be used to create a bindable editor widget to restore the aborted line: recover-line() { LBUFFER=$ZLE_LINE_ABORTED RBUFFER=; } zle -N recover-line and then either bind recover-line to a key sequence or use `M-x recover-line <RET>’.

The parameter ZLE_STATE, available in user-defined line editor widgets, gives information on the state of the line editor. Currently this is whether the line editor is in insert or overwrite mode.

Miscellaneous options

The new shell option HIST_LEX_WORDS causes history lines read in from a file to be split in the same way as normal shell lines, instead of simply on whitespace. It’s an option as although the result is more accurate it can take a long time when the history size is large.

The shell option MONITOR can be set in non-interactive shells, and also in subshells (as created by surrounding commands with parentheses), turning on job control for that subshell. The initial behaviour of a subshell is still to turn job control off, however if the new POSIX_JOBS option is set MONITOR remains active in subshells.

The new shell option POSIX_CD, active in emulations of POSIX-based shells, makes the cd builtin POSIX-compatible.

The POSIX_JOBS option already referred to has various other compatibility enchancements.

The new shell option POSIX_STRINGS makes a null character in $’…’ expansion terminate the string, as is already the case in bash. This is not particularly useful behaviour but may become a POSIX requirement.

The new shell option POSIX_TRAPS causes the EXIT trap to behave in the same way as in other shells, i.e. it is only run when the shell exits.

The new shell option SOURCE_TRACE causes the shell to report files containing shell code that the shell executes directly, i.e. startup files or files run with the `source’ or `.’ builtins.

The shell option SUN_KEYBOARD_HACK has been supplemented by a more general mechanism: the KEYBOARD_HACK variable defines the character to be ignored.

Add-on modules and function

The module zsh/system has a new “zsystem” builtin whose subcommands perform system level tasks. Currently “zsystem flock” performs advisory file locking (for aficionados, this uses the fcntl() system call so works over the network on Linux). This is a particularly convenient way of locking files for the length of a subshell. “zsystem supports flock” provides a test for this feature.

There is now a function system for recording and restoring recently entered directories in a persistent fashion, with support in completion and (if explicitly installed) dynamic directory expansion. See the entry for cdr in the zshcontrib manual page.

Changes between versions 4.3.9 and 4.3.10

The command “emulate <mode> -c …” evaluates an expression in a given emulation. The emulation is sticky for functions defined within the expression.

The variable CORRECT_IGNORE gives a pattern that can be ignored in spelling correction. CORRECT_IGNORE=’_*’ ignores completion functions.

The option POSIX_ALIASES improves compatibility of aliases with other shells.

The variable ZSH_PATCHLEVEL can be used to test for unreleased versions of the shell; it is present but less useful in released versions.

The variables ZLE_REMOVE_SUFFIX_CHARS and ZLE_SPACE_SUFFIX_CHARS allow more control over the way automatically removed suffixes are treated in completion.

Major changes between versions 4.3.6 and 4.3.9

The option COMBINING_CHARS has been added. When it is set, the line editor assumes the terminal is capable of displaying zero-width combining characters (typically accents) correctly as modifications to the base character, and will act accordingly. Note it is not set by default owing to vagaries of terminals. The system is reported to work on MacOS, where this is particularly important as accented characters in file names are stored in their decomposed form (i.e. with base and combining characters).

The option HIST_FCNTL_LOCK has been added to provide locking of history files using the system call fcntl(). On recent NFS implementations this may provide better reliability.

The syntax ~[…] provides a dynamic form of directory naming, supplementing the existing static ~name syntax. A user-defined shell function, zsh_directory_name, is used to handle both expansion of names to directories and contraction of directories to names.

Patterns can now be used in incremental searches with the new widgets history-incremental-pattern-search-backward and history-incremental-pattern-search-forward. These are not bound to keys by default.

Highlighting and colouring of sections of the command line is now supported, controlled by the array parameter zle_highlight and the ZLE special parameter region_highlight.

Colouring of prompts is now supported within the shell by prompt escapes. The prompt theme system has been updated.

Various changes have been added to make debugging of shell code easier:

• As noted in README, the option DEBUG_BEFORE_CMD is now set by default.
• In DEBUG traps, $ZSH_DEBUG_CMD gives the code for which the trap is called as a string.
• “setopt ERR_EXIT” in a DEBUG trap causes the code not to be executed.
• $ZSH_SUBSHELL indicates the subshell level at which code is being executed.
• The zsh/parameter module has various additional arrays similar to the existing $funcstack and $functrace, namely $funcsourcetrace and $funcfiletrace. The consistency and informativeness of the output of all these arrays has been improved.
• Prompt escapes %x and %I show the source file and line number in debug prompts (compare %N and %i which show names and line numbers in the execution environment).
• The option NO_MULTI_FUNCDEF can turn off multiple definition of functions at once, a rarely used feature that can cause problems with misplaced "()".
• The “fc” builtin has been enhanced to make non-interactive use possible and output consistent when the history is manipulated with "print -s".

The completion style accept-exact-dirs has been added. When true, this suppresses attempts to complete non-final directory segments of a filename path when the directory exists. (For example, /home/pws/src/zsh/<TAB> discovers that /home/pws/src/zsh exists and leaves the directory component alone, while /h/p/s/z/<TAB> completes to /home/pws/src/zsh/… as before.) This should improve completion behaviour noticeably in special cases, such as remote paths under Cygwin.

Major changes between versions 4.3.5 and 4.3.6

cd, chdir, pushd and popd now take a -q option to suppress side effects including printing the directory stack (for pushd and popd) and executing the chpwd hook functions (for all four).

The parameter subscript (e) flag now forces the argument to be treated as a string where it would previously have been treated as a pattern, for example ${array[(ie)*]} substitutes the index of the element whose value is "*".

Major changes between versions 4.3.4 and 4.3.5

• The new extended globbing flag (#cN,M) behaves similarly to the extended regular expression syntax {N,M}.
• The zsh/datetime module has been enhanced and a calendar function system has been added along the lines of (but much enhanced from) the traditional Unix “calendar” utility. This is still under development. See the zshcalsys manual. (The calendar functions were in 4.3.4 but were not listed in this file. There have been significant enhancements since 4.3.4.)
• A new module zsh/curses provides a builtin zcurses for access to to the curses screen manipulation package. See the entry for zsh/curses in the zshmodules manual.
• The module system has been enhanced to support the notion of “features” that give more control over which builtins, parameters, conditions and math functions are loaded from a module. In particular, “zmodload -F zsh/stat b:zstat” makes the builtin previously called “stat” available as “zstat” (only) to avoid clashes with a system command named "stat".

Major changes between versions 4.2 and 4.3.4

• There is support for multibyte character sets. This is now reasonably close to complete, although Unicode combining characters don’t work properly. See Multibyte Character Support in INSTALL.
• The shell can now run an installation function for a new user (a user with no .zshrc, .zshenv, .zprofile or .zlogin file) without any additional setting up by the administrator. See “THE ZSH/NEWUSER MODULE” in the zshmodules manual page.
• The manual now has a Roadmap section (manual page zshroadmap) to give new users an indication of the most interesting parts of the manual.
• New option PROMPT_SP (on by default): works around the problem that the line editor can overwrite output with no newline at the end. See the zshoptions manual page.
• New option HIST_SAVE_BY_COPY (on by default): history is saved by copying and renaming instead of directly overwriting. See the zshoptions manual page.
• New redirection syntax e.g. {myfd}>file opens a new file descriptor and stores the number in $myfd, so that >&$myfd will work. Chosen not to break existing code (and to be compatible with proposals for the Korn shell). See the section REDIRECTION in the zshmisc manual page.
• Substitutions of the form ${var:-"$@"}, ${var:+"$@"} and similar where word-splitting is applied to the text after the :- or :+ (in particular, where the SH_WORD_SPLIT option is in effect for compatibility) now behave as in other Bourne- and POSIX-compatible shells when in the appropriate emulation mode.
• New Posix-style zsh-specific tests [[:IDENT:]], [[:IFS:]], [[:IFSSPACE:]], [[:WORD:]] test if character can appear in identifier, is an IFS character, is an IFS whitespace character, or is considered as part of a word (is alphanumeric or appears in $WORDCHARS). These works correctly on multibyte characters if the appropriate support is present. See the section FILENAME GENERATION in the zshexpn manual page.
• Time comparisons on files when sorting or using test operators will use high-resolution timestamps when available. This gives a resolution of a nanosecond instead of a second.
• The idiom =(<<<…) is optimised so that the shell internally turns the … into the contents of a file whose name is then substituted. The syntax has always been usable by means of the NULLCMD feature, but previously it generated an intermediate process; it has now been rewritten along the same lines as the optimisation for $(<…) that inserts a file into the command line without the use of an external programme.
• Supplied functions catch and throw provide limited support for exception handling using the `{ … } always { … }’ syntax. See the section EXCEPTION HANDLING in the zshcontrib manual page.
• Signals now accept the SIG as part of the name for compatibility with other shells.
• Editor function argument-base allows non-decimal arguments for editor widgets. See the entry in the zshzle manual page.
• As always, there are many enhancements to completion functions.

Changes since zsh 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[®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 expanions 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 qualifiers (+func) is shorthand for (e:func:) (calls command, typically shell function, with no argument).

New features between zsh versions 4.0 and 4.2Configuration:

• 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 provides zselect builtin as interface to select system call

Completion system:

• general improvements to command and context support, low-level functions, display code.
• in verbose mode, matches with the same description are grouped
• highly configurable completions for values of specific parameters, specific redirections for specific commands
• support for bash completion functions (typically zsh native functions are more powerful where available)
• New completions provided for (some of these may be in later 4.0 releases): valgrind, tidy, texinfo, infocmp, Java classes, larch, limit, locale parameters, netcat, mysqldiff, mt, lsof, elinks, ant, debchange (dch), email addresses, file system types, Perforce, xsltproc. Plus many others.

Line editor:

• special parameters $PREDISPLAY, $POSTDISPLAY available in function widgets to configure uneditable text (for narrowing)
• recursive editing
• supplied widgets read-from-minibuffer, replace-string use these features (more intuitive prompting and argument reading than 4.0)
• access to killed text via $CUTBUFFER and $killring
• supplied highly configurable word widgets forward-word-match etc., can set what constitutes a word interactively or in startup script (implement bash-style behaviour, replacing previous bash-* word widgets)
• interface to incremental search via $LASTSEARCH
• better handling of keymaps in zle and widgets
• better support for output from user-defined widgets while zle is active
• tetris game which runs entirely in zle
• several other contributed widgets

Local internal improvements:

• disowned jobs are automatically restarted
• \u and \U print escapes for Unicode
• read -d <delimiter> allows a custom line ending.
• read -t <timeout>.
• line numbers in error messages and $PS4 output are more consistent
• `=prog’ expands only paths, no longer aliases for consistency
• job display in prompts; `jobs’ command output can be piped
• prompts: new $RPROMPT2, %^, %j, %y, enhanced %{, %}, %_.
• rand48() function in zsh/mathfunc for better randomness in arithmetic (if the corresponding math library function is present)
• $SECONDS parameter can be made floating point via `typeset -F SECONDS’ for better timing accuracy
• improvements to command line history mechanism
• job table is dynamically sized, preventing overflow (typically seen previously in complex completions).
• many bugfixes

New features in zsh version 4.0.1Compared with 3.1.9, there are mostly incremental improvements to

• the new completion system — more functions, completers, styles…
• the line editor
• handling of signals and traps
• the configuration system, particularly for modules
• Cygwin support (now essentially complete)
• arithmetic evaluation
• the zpty (pseudoterminal handling) module
• the test suite

plus various bug fixes and compatibility improvements.

The alias modules (zle.so as an alias for zsh/zle.so, etc.) have been removed; use `zmodload -A’ to load modules under other names. This is irrelevant if you are upgrading from 3.0.

Compared with the 3.0 series of releases (the last stable set), the most significant of a large number of improvements in the shell are:

• Dynamically loadable modules with hierarchical naming system
• Shell functions as editor functions, with much additional builtin support
• Incredibly rich new completion system; just needs a single initialization command to provide completion for all sorts of commands and contexts
• Associative arrays
• Lots of new features in parameter substitution and globbing; more logical handling of nested parameter substitutions
• Rewritten pattern-matching (globbing) code supports approximate and case-insensitive matching and backreferences
• Various custom modules for pty’s, FTP, special parameters, etc.
• Rewrites of many internal parts of the code: execution code to provide compilation to internal representation, pattern matching
• Floating point arithmetic and mathematical functions module
• A test suite
• Various new options for compatibility with this, that and the other

See the 3.1.x changes below for more detail.

New features in zsh version 3.1.8 and 3.1.9

These are primarily bug-fix versions. There are only a few user-visible changes.

• Array slices ${array[a,b]} with b < a now correctly have zero length.

New features in zsh version 3.1.7

Further enhancements to new completion system:

• Comprehensive context-sensitive configuration via `styles’, which can be set by the menu-driven front end in compinstall
• General mechanism for setting patterns to be ignored in a completion; overriding of patterns to be matched for functions
• New completers: _prefix to complete word before cursor, _ignored to complete using words so far ignored (like $fignore but more powerful), _history to complete words from shell history
• Multiple use of completers with different options, similarly splitting of different types of completion (`tags’) so they are considered with different styles
• Many more supplied completions for standard commands which work out of the box, and better handling of command line options/arguments which behave in the usual way
• $fpath now set up to use installed functions by default; functions can be loaded just by `autoload -U compinit; compinit’
• Much improved handling of nested quoting and nested braces
• New LIST_PACKED and LIST_ROWS_FIRST completion options and corresponding styles
• compctl library separated out (frozen but still supported)
• User-friendly introduction available at zsh website

Additions to complist listing library (coloured completion and menu selection):

• Listings can be shown page by page (are by default for new completion)
• Menu selection allows full up and down scrolling of long lists

Other editing features:

• new parameters $PENDING, $MARK, $BUFFERLINES
• Easy display of a prompt from within an editing widget

Code parsing, storing and execution:

• Completely new system of storing code internally, greatly optimised
• Much less memory for shell functions etc.
• Can compile shell functions to .zwc `wordcode’ functions for fast loading
• Can create `digest’ files of entire directories in .zwc format

Parameters:

• Floating point support added, similar to ksh93, `typeset -F’ and `typeset -E’ declare floating point variables; usual C/Fortran-like rules for integer/float conversion
• Mathematical library zsh/mathfunc contains all the standard mathematical functions for use in arithmetical expressions
• Improved parsing of arithmetical expressions and better error messages
• Special parameters can be made local
• `typeset -h’ hides specialness of parameters, either as parameter attribute or when declaring new local variable
• Local parameters can now be exported as in other shells; new option GLOBAL_EXPORTS on by default provides old behaviour that `typeset -x’ referred to global parameters.
• zsh/parameter module enhanced: now needed for new completion; parameters provided have `-h’ flag set so that they are hidden by `typeset’, so that existing functions don’t need to be changed
• Quotes can be stripped from parameter values with ${(Q)…}, providing reverse of ${(q…)…} facility

Globbing and pattern matching:

• Pattern matching rewritten for efficiency
• Supports `backreferences’, i.e. extracting parenthesised chunks of matches, e.g. [[ $foo = (#b)(*/)[^/]* ]] stores the part of $foo up to the last / in $match[1] and the indexes of the match in $mbegin[1], $mend[1]. (#m) is also available to set $MATCH to the entire match and corresponding $MBEGIN, $MEND: useful in parameter substitutions like ${…/…/…}.
• (#s) and (#e) match start and end of pattern like ^ and $ in regular expression, useful in complex expressions such as ((#s)|/)dirname((#e)|/) and in parameter expressions.
• Depth-first/last listing of recursive glob lists

Functions etc.:

• `autoload -X’ inside a function body instructs the shell to bootstrap the function at that point
• `autoload +X fn’ says load the function fn but don’t execute it
• Prompt `themes’ make customization of prompts easier

Modules:

• New hierarchical naming scheme for modules; supplied modules go into zsh subdirectory, so zle becomes zsh/zle etc.; aliases supplied for compatibility for existing code, but the new format should be used in future.
• zmodload is more consistent between dynamically and statically linked shells
• zsh/zftp and its function suite support multiple sessions (zfsession command); zftransfer allows transfer of files between two ftp sessions with no local file; use styles for e.g. progress style; IPv6 supported; recursive put `zfput -r’ for uploads
• zsh/zpty module creates pseudoterminal and allows builtin `expect’-like behaviour

Other:

• Test suite, not yet complete (`make test’)
• use of Linux task limits
• Many fixes including output redirection with `setopt xtrace’ and other redirection fixes; NIS+ problem.
• Better null-command behaviour in sh and csh emulation
• Internal memory usage optimisations

New features in zsh version 3.1.6 (beta version)

Note also the changes for 3.0.6, which include changes between 3.1.5. and 3.1.6.

New completion system via shell functions; massive degree of programmability and configurability:

• ready-made function suite to use, see zshcompsys(1)
• approximate completion and spelling correction via completion
• control over matching for case-independence, partial word completion, etc.
• menu selection: choose a completion by moving the cursor
• coloured completion lists
• completion of filenames in quotes is now more reliable; splitting quoted strings into command arguments is also possible.

Other editing changes:

• enhancements to function/editing interface: new parameters, numeric arguments, string argument passing, reading keys from widgets.
• the old history-search-{back,for}ward behaviour and bindings have returned (up to minor details).
• BASH_AUTO_LIST option to show completion list only on second key press.
• the ZBEEP parameter gives a string to output instead of beeping, allowing you to have a visual bell.

History changes: new options HIST_NO_FUNCTIONS, HIST_EXPIRE_DUPS_FIRST, HIST_FIND_NO_DUPS, HIST_IGNORE_ALL_DUPS, INC_APPEND_HISTORY, HIST_SAVE_NO_DUPS, SHARE_HISTORY, allow better control of when history is read and written and how duplicates are handled. New format for history saves.

Associative arrays plus enhanced parameter substitutions to retrieve keys and values.

Globbing changes:

• Case-insensitive and approximate globbing.
• Ordering and indexing of globbing matches, e.g. *(om[1]) picks most recently modified file.
• General file mode qualifier with chmod(1)-like syntax, e.g. *(f:u+wx:)

New loadable modules:

• zftp, plus associated function suite, for turning your zsh session into an FTP session too
• parameter, for examining and altering shell hash tables via an associative array interface.
• mapfile, for reading and writing external files via an associative array interface.

Debugging and prompt enhancements:

• $PS4 can contain %i for $LINENO as well as %N for script or function names (default PS4 changed), also %_ for current shell structure executing;
• Prompt truncation %<…< is now more flexible: it applies to a whole section of the prompt, not just one escape. You need to put %<< after the truncated escape to get the old behaviour.
• %20(l.yes.no) in prompts prints yes if at least 20 characters have been output, else no (e.g. for outputting extra newlines).

Parameter and expansion changes

• `typeset -t MYPATH mypath’ creates tied path/PATH-like variables
• `typeset -g’ allows operations on parameters without making them local
• New expansions
  • ${(t)param} prints type information for $param
  • ${§param} treats value of $param as the name of a param to substitute
  • ${foo:q} can quote replaced parameter text from expansion
  • ${foo/old/new} substitution, like bash; also (S) flag for shortest match
  • $foo[(b.2.i)bar] starts searching $foo for bar starting at 2nd match

Builtin and function changes

• stat module: `stat -H hash foo’ gives you e.g. $hash[mtime]
• `autoload -U’ autoloads functions without alias expansion.

Other new options:

• LOCAL_TRAPS allows signal traps to be local to functions (as in ksh).
• NO_RCS can now be turned on at any point in initialization files.
• NO_GLOBAL_RCS can force /etc/z* files after /etc/zshenv to be skipped. (Please don’t use this as an excuse to stuff more into /etc/zshenv!)
• Existing MAGIC_EQUAL_SUBST option is more useful; any argument containing …=~…:~… will perform filename expansion on the ~ (previously, the string before `=’ had to look like a parameter name).

Configuration changes:

• Generation of signal names should be more reliable
• Customizable installation of shell functions from distribution.

New features in zsh version 3.0.6

Most of these changes are designed to improve compatibility with zsh version 3.1.6, the latest development release. However, this release also fixes all known Year 2000 (Y2K) bugs in zsh 3.0.

History changes:

• whitespace between words is ignored in history searches.
• new option HIST_REDUCE_BLANKS removes extra whitespace in the stored history.
• support for reading (but not writing) version 3.1.6 history files.

Globbing changes:

• the a, c, and m glob qualifiers can now test time in seconds.
• globbing of number ranges behaves more like character ranges in that it can match a prefix of a number, e.g. `<1-5>*’ matches 1, 2, 3, 4, 5, 17, 23skiddoo, 5986, etc., but not 6, 7, 8ball, 911, etc.

Parameter and expansion changes:

• expansion of ~ and other globbing flags via ${~param} do not depend upon EXTENDED_GLOB (bug fix).
• nested parameter substitutions require braces (this was always the documented behavior, but previous parsers didn’t enforce it).
• quote only nested expansion, e.g. ${(f)"$(<file)"} reads complete `file’, then splits lines into array.

Builtin and function changes:

• `typeset -U’ works on the colon-array version of linked parameters.
• `typeset +f’ and `functions +’ output the names (only) of functions.
• `emulate -L’ has the effect of `setopt localoptions’.
• in fn1() { local foo; unset foo; foo=bar; }, foo is restored at local level, whereas if the `unset foo’ appeared in a nested function it would have been restored at global level, which was presumably wrong.
• `foo=bar >&file’ is a redirection, not a NULLCMD.
• any single complex command, such as `case … esac’, parses as if semicolon-terminated (bug fix).
• the shell function `preexec’, if defined, is run after parsing each command line but before executing the command.

Other changes:

• the option PRINT_EIGHT_BIT causes zsh to emit raw bytes in prompts and completion lists even if the system ctype(3) package says that those bytes are not “printable.”

Debugging enhancements:

• LINENO is now very much more useful in scripts and functions and is reported correctly in most error messages.
• ERREXIT behavior is now consistent with newer Bourne-like shells, e.g. with respect to `if’ tests that fail.

Configuration changes:

• Large file and 64-bit integers on 32-bit machines supported where provided by OS.
• a few more system features, such as getpwnam/getpwuid, are tested for.

New features in zsh version 3.1 (beta version)

On most operating systems zsh can load binary modules dynamically at run-time. ZLE and the compctl builtin are now reside in a separate module which is loaded automatically on demand.

for ((expr; expr; expr)) do … done loop syntax from AT&T ksh93 is now supported.

POSIX globbing character classes ([:alnum:] etc.) are now supported.

ksh’s case fall-through feature (;&) is supported.

ksh93’s $’’ quoting syntax is supported.

Restricted mode is now supported. This is controlled by the new option RESTRICTED (-r).

New options BARE_GLOB_QUAL, HIST_NO_FUNCTIONS (alias NO_LOG), KSH_GLOB, PRINT_EIGHT_BIT, PROMPT_BANG, PROMPT_PERCENT, RM_STAR_WAIT.

Options ALWAYS_LAST_PROMPT, APPEND_HISTORY, AUTO_LIST, AUTO_MENU, AUTO_PARAM_KEYS, AUTO_PARAM_SLASH, AUTO_REMOVE_SLASH, LIST_AMBIGUOUS and LIST_TYPES are now on by default.

In ZLE, arbitrarily many keymaps can be defined. Multi-character keybindings now work.

Completion can be performed within a brace expansion.

EMACS-like universal-argument function.

New features in zsh version 3.0

Trailing “/” in a glob pattern now works like in other shell thus it can no longer be used as a shorthand for "(/)".

Much improved sh/ksh emulation. When zsh is invoked as sh it mostly conforms to POSIX 1003.2.

Enhanced parameter expansion features: new flags: A, @, e, W, p, f, F. Expansions can be nested. For example, “${${(M)${(f@)$(<builtin.pro)}:#char*}[2][(w)3]}” expands to the third word of the second line of builtin.pro which begins with char. See zshexpn(1) for the details.

***/foo glob does recursive directory search following symbolic links.

Traps defined by the trap builtin are now executed in the current shell environment and not as a shell function. This means that $1 is not set to the signal number. Of course the TRAPxxx functions continue working as before.

Traps defined by the trap builtin are reset to their default values in subshells.

Option names can be prefixed by `no’ to unset an option. setopt no_option_name is the same as unsetopt option_name. This change affects the output of the setopt and unsetopt builtins when these are invoked without arguments. See the zshoptions manual page for more explanation.

!, {, } and [[ are now reserved words. Things like [[-z $foo]] or {foo} should not be used. {foo} still works if the IGNORE_BRACES option is not set but this feature may be removed in the future. [[ -z $foo ]] and { foo } should be used instead.

HOSTTYPE special parameter is removed. The new OSTYPE, MACHTYPE and VENDOR parameters should be used instead.

VERSION parameter is renamed to ZSH_VERSION

exec now saves the history in interactive shells. If you do not like this behaviour you can alias exec to 'unset HISTFILE ; exec’.

${~spec}, ${=spec} and ${^spec} used to toggle the effect of globsubst/shwordsplit/rcexpandparam. Now these force the corresponding option on. ~, = or ^ can be doubled to force the relevant option off for the substitution.

Explicitly requested word splitting like ${=spec} or ${(s:delim:)spec} will be executed even if the substitution is double quoted.

The right-hand side of assignments are no longer globbed by default hence assignment foo=* will assign ‘*’ as a value of foo. Use the foo=( * ) array assignment syntax to get the old behaviour. Alternatively the GLOB_ASSIGN can be set to emulate the old behaviour but the usage of this option is strongly discouraged and this option may be completely removed in the future.

foo=$bar no longer creates an array even if bar is an array. Use foo=( $bar ) or even better, foo=( "$bar[@]" ) instead.

When foo is an array parameter ${#foo} will always return the length of the array even if the substitution is double quoted. ${©#foo} should be used to get back the old behaviour.

When the prompt_subst option is set prompts are fully expanded using parameter expansion, command substitution and arithmetic expansion. In 2.5 backquote substitution was not performed in the prompts so this change might cause problems in some startup scripts if ` is used literally in prompts.

History substitution is now not performed if the history escape character appears in a single-quoted string. This may break some interactive shell functions which use \! in single-quoted strings.

The UID, EUID, GID, EGID parameters can be assigned now. The assignment executes the setuid(), seteuid(), setgid(), setegid() respectively. On systems where setuid and seteuid is not supported these functions are emulated using setreuid or setresuid which may result in a different behaviour.

Assigning the USERNAME parameter will call setuid(uid) where uid is the user id of the specified user.

The privileged (-p) option is automatically set on invocation if euid != uid or egid != gid. If this option is set no user startup files are sourced. The shell will drop privileges when this option is unset by resetting its euid to uid and its egid to gid.

The =number substitution for accessing the directory stack is changed to ~number to allow =command substitution when a command name begins with a digit.

<> is a redirection operator which opens the standard input for both reading and writing. To match a number use <->

Option letters -1 and -C for PRINT_EXIT_VALUE and NO_CLOBBER are swapped: `set -C’ sets NO_CLOBBER and `set -1’ sets PRINT_EXIT_VALUE.

AUTO_PUSHD behaviour is changed. Now cd without arguments will always go to the $HOME directory even if AUTO_PUSHD is set and PUSHD_TO_HOME is not set. If you preferred the old behaviour you can alias cd to pushd.

IFS word splitting with SH_WORD_SPLIT and the splitting of the input in the read builtin has changed in cases when IFS contains characters other than <space>, <tab>, <newline>. See the description of IFS in the zshparam manual page for more details.

New features in zsh version 2.5

Greatly expanded completion possibilities. Programmable completion allows detailed control over what arguments of what commands can be completed to what. See dots/zcomp in the distribution for examples.

Expand filenames with ~ and = on the right hand side of parameter assignments. New option MAGIC_EQUAL_SUBST to do it in all identifier=expression arguments.

${+name} becomes 1 or 0 if name is set or unset. ${~spec} toggles GLOB_SUBST in substitution. Parameter substitution takes lots of flags in the format ${(flags)name}.

New glob qualifiers for block/character special files, times in glob qualifiers can be in months, weeks, days, hours, minutes. Qualifiers can work on links or on what they point to. Qualifiers separated by commas are or-ed.

New parameter substitution modifiers (fFwW) to repeat actions. New option CSH_JUNKIE_HISTORY.

New line editor functions history-beginning-search-backward, history-beginning-search-forward, expand-or-complete-prefix, push-input, push-line-or-edit.

Assign to part of a string, use qualifiers on string subscription with $foo[(qual)2,5]

New parameters: EGID, EUID, KEYTIMEOUT

New prompt escape sequence %_ to get constructs like for and while in the secondary prompt. %E in prompt clears to end of screen.

Conditional expressions in PROMPT and WATCHFMT.

New options ALWAYS_LAST_PROMPT, ALWAYS_TO_END, AUTO_PARAM_KEYS, COMPLETE_ALIASES, COMPLETE_IN_WORD, CSH_JUNKIE_HISTORY, GLOB_SUBST, LIST_AMBIGUOUS, MAGIC_EQUAL_SUBST, NO_FLOW_CONTROL, PROMPT_SUBST

New option -m to many builtins makes arguments subject to pattern matching.

Bindkey can now bind both key sequences and prefixes of those. You can for example bind ESC and function keys sending ESC sequences.

Additional options to read builtin to use in functions called by completion.

New options to print to sort arguments and print them in columns.

Some additional resource limits can be specified.

Some editor functions now work in the minibuffer.

Disclaimer Last modified: 2020-02-15