This is zsh.info, produced by makeinfo version 4.6 from tzsh.texi. INFO-DIR-SECTION Utilities START-INFO-DIR-ENTRY * ZSH: (zsh). The Z Shell Manual. END-INFO-DIR-ENTRY  File: zsh.info, Node: Top, Next: The Z Shell Manual, Prev: (dir), Up: (dir) The Z Shell Manual ****************** This Info file documents Zsh, a freely available UNIX command interpreter (shell), which of the standard shells most closely resembles the Korn shell (ksh), although it is not completely compatible. Version 4.2.0-pre-4, last updated March 12, 2004. * Menu: * The Z Shell Manual:: * Introduction:: * Invocation:: * Files:: * Shell Grammar:: * Redirection:: * Command Execution:: * Functions:: * Jobs & Signals:: * Arithmetic Evaluation:: * Conditional Expressions:: * Prompt Expansion:: * Expansion:: * Parameters:: * Options:: * Shell Builtin Commands:: * Zsh Line Editor:: * Completion Widgets:: * Completion System:: * Completion Using compctl:: * Zsh Modules:: * TCP Function System:: * Zftp Function System:: * User Contributions:: --- Indices --- * Concept Index:: * Variables Index:: * Options Index:: * Functions Index:: * Editor Functions Index:: * Style and Tag Index:: --- The Detailed Node Listing --- Introduction * Author:: * Availability:: * Mailing Lists:: * The Zsh FAQ:: * The Zsh Web Page:: * The Zsh Userguide:: * See Also:: Invocation * Compatibility:: * Restricted Shell:: Shell Grammar * Simple Commands & Pipelines:: * Precommand Modifiers:: * Complex Commands:: * Alternate Forms For Complex Commands:: * Reserved Words:: * Comments:: * Aliasing:: * Quoting:: Expansion * History Expansion:: * Process Substitution:: * Parameter Expansion:: * Command Substitution:: * Arithmetic Expansion:: * Brace Expansion:: * Filename Expansion:: * Filename Generation:: Parameters * Array Parameters:: * Positional Parameters:: * Local Parameters:: * Parameters Set By The Shell:: * Parameters Used By The Shell:: Options * Specifying Options:: * Description of Options:: * Option Aliases:: * Single Letter Options:: Zsh Line Editor * Movement:: * History Control:: * Modifying Text:: * Arguments:: * Completion:: * Miscellaneous:: Completion Widgets * Special Parameters:: * Builtin Commands:: * Condition Codes:: * Matching Control:: * Completion Widget Example:: Completion System * Initialization:: * Completion System Configuration:: * Control Functions:: * Bindable Commands:: * Completion Functions:: * Completion Directories:: Completion Using compctl * Command Flags:: * Option Flags:: * Alternative Completion:: * Extended Completion:: * Example:: Zsh Modules * The zsh/cap Module:: * The zsh/clone Module:: * The zsh/compctl Module:: * The zsh/complete Module:: * The zsh/complist Module:: * The zsh/computil Module:: * The zsh/datetime Module:: * The zsh/deltochar Module:: * The zsh/example Module:: * The zsh/files Module:: * The zsh/mapfile Module:: * The zsh/mathfunc Module:: * The zsh/parameter Module:: * The zsh/pcre Module:: * The zsh/sched Module:: * The zsh/net/socket Module:: * The zsh/stat Module:: * The zsh/system Module:: * The zsh/net/tcp Module:: * The zsh/termcap Module:: * The zsh/terminfo Module:: * The zsh/zftp Module:: * The zsh/zle Module:: * The zsh/zleparameter Module:: * The zsh/zprof Module:: * The zsh/zpty Module:: * The zsh/zselect Module:: * The zsh/zutil Module:: TCP Function System * TCP Functions:: * TCP Parameters:: * TCP Examples:: * TCP Bugs:: Zftp Function System * Installation:: * Zftp Functions:: * Miscellaneous Features:: User Contributions * Utilities:: * Prompt Themes:: * ZLE Functions:: * Other Functions::  File: zsh.info, Node: The Z Shell Manual, Next: Introduction, Prev: Top, Up: Top The Z Shell Manual ****************** This document has been produced from the texinfo file zsh.texi, included in the Doc sub-directory of the Zsh distribution. Producing documentation from zsh.texi ===================================== The texinfo source may be converted into several formats: The Info manual The Info format allows searching for topics, commands, functions, etc. from the many Indices. The command `makeinfo zsh.texi' is used to produce the Info documentation. The printed manual The command `texi2dvi zsh.texi' will output zsh.dvi which can then be processed with `dvips' and optionally `gs' (Ghostscript) to produce a nicely formatted printed manual. The HTML manual An HTML version of this manual is available at the Zsh web site via: http://zsh.sunsite.dk/Doc/. (The HTML version is produced with `texi2html', which may be obtained from http://www.mathematik.uni-kl.de/~obachman/Texi2html/. The command is `texi2html -split chapter -expand info zsh.texi'. If necessary, upgrade to version 1.64 of texi2html.) For those who do not have the necessary tools to process texinfo, precompiled documentation (PostScript, dvi, info and HTML formats) is available from the zsh archive site or its mirrors, in the file zsh-doc.tar.gz. (See *Note Availability:: for a list of sites.)  File: zsh.info, Node: Introduction, Next: Invocation, Prev: The Z Shell Manual, Up: Top Introduction ************ Zsh is a UNIX command interpreter (shell) usable as an interactive login shell and as a shell script command processor. Of the standard shells, zsh most closely resembles `ksh' but includes many enhancements. Zsh has command line editing, builtin spelling correction, programmable command completion, shell functions (with autoloading), a history mechanism, and a host of other features. * Menu: * Author:: * Availability:: * Mailing Lists:: * The Zsh FAQ:: * The Zsh Web Page:: * The Zsh Userguide:: * See Also::  File: zsh.info, Node: Author, Next: Availability, Up: Introduction Author ====== Zsh was originally written by Paul Falstad . Zsh is now maintained by the members of the zsh-workers mailing list . The development is currently coordinated by Peter Stephenson . The coordinator can be contacted at , but matters relating to the code should generally go to the mailing list.  File: zsh.info, Node: Availability, Next: Mailing Lists, Prev: Author, Up: Introduction Availability ============ Zsh is available from the following anonymous FTP sites. These mirror sites are kept frequently up to date. The sites marked with _(H)_ may be mirroring ftp.cs.elte.hu instead of the primary site. Primary site ftp://ftp.zsh.org/pub/zsh/ http://www.zsh.org/pub/zsh/ Australia ftp://ftp.zsh.org/pub/zsh/ http://www.zsh.org/pub/zsh/ Denmark ftp://sunsite.dk/pub/unix/shells/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ _(H)_ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ http://www.cs.elte.hu/pub/zsh/ ftp://ftp.kfki.hu/pub/packages/zsh/ Israel ftp://ftp.math.technion.ac.il/pub/zsh/ http://www.math.technion.ac.il/pub/zsh/ Japan ftp://ftp.win.ne.jp/pub/shell/zsh/ ftp://ftp.ayamura.org/pub/zsh/ Korea ftp://linux.sarang.net/mirror/system/shell/zsh/ Netherlands ftp://ftp.demon.nl/pub/mirrors/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Poland ftp://sunsite.icm.edu.pl/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ ftp://ftp.kappa.ro/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/mirrors/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ ftp://sunsite.org.uk/packages/zsh/ USA ftp://uiarchive.uiuc.edu/mirrors/ftp/ftp.zsh.org/pub/ ftp://ftp.rge.com/pub/shells/zsh/ http://zsh.disillusion.org/ http://foad.org/zsh/ The up-to-date source code is available via anonymous CVS from Sourceforge. See http://sourceforge.net/projects/zsh/ for details.  File: zsh.info, Node: Mailing Lists, Next: The Zsh FAQ, Prev: Availability, Up: Introduction Mailing Lists ============= Zsh has 3 mailing lists: Announcements about releases, major changes in the shell and the monthly posting of the Zsh FAQ. (moderated) User discussions. Hacking, development, bug reports and patches. To subscribe or unsubscribe, send mail to the associated administrative address for the mailing list. YOU ONLY NEED TO JOIN ONE OF THE MAILING LISTS AS THEY ARE NESTED. All submissions to `zsh-announce' are automatically forwarded to `zsh-users'. All submissions to `zsh-users' are automatically forwarded to `zsh-workers'. If you have problems subscribing/unsubscribing to any of the mailing lists, send mail to . The mailing lists are maintained by Karsten Thygesen . The mailing lists are archived; the archives can be accessed via the administrative addresses listed above. There is also a hypertext archive, maintained by Geoff Wing , available at http://www.zsh.org/mla/.  File: zsh.info, Node: The Zsh FAQ, Next: The Zsh Web Page, Prev: Mailing Lists, Up: Introduction The Zsh FAQ =========== Zsh has a list of Frequently Asked Questions (FAQ), maintained by Peter Stephenson . It is regularly posted to the newsgroup `comp.unix.shell' and the `zsh-announce' mailing list. The latest version can be found at any of the Zsh FTP sites, or at http://www.zsh.org/FAQ/. The contact address for FAQ-related matters is .  File: zsh.info, Node: The Zsh Web Page, Next: The Zsh Userguide, Prev: The Zsh FAQ, Up: Introduction The Zsh Web Page ================ Zsh has a web page which is located at http://www.zsh.org/. This is maintained by Karsten Thygesen , of SunSITE Denmark. The contact address for web-related matters is .  File: zsh.info, Node: The Zsh Userguide, Next: See Also, Prev: The Zsh Web Page, Up: Introduction The Zsh Userguide ================= A userguide is currently in preparation. It is intended to complement the manual, with explanations and hints on issues where the manual can be cabbalistic, hierographic, or downright mystifying (for example, the word `hierographic' does not exist). It can be viewed in its current state at http://zsh.sunsite.dk/Guide/. At the time of writing, chapters dealing with startup files and their contents and the new completion system were essentially complete. The Zsh Wiki ============ A `wiki' website for zsh has been created at http://www.zshwiki.org/. This is a site which can be added to and modified directly by users without any special permission. You can add your own zsh tips and configurations.  File: zsh.info, Node: See Also, Prev: The Zsh Userguide, Up: Introduction See Also ======== man page sh(1), man page csh(1), man page tcsh(1), man page rc(1), man page bash(1), man page ksh(1) `IEEE Standard for information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities', IEEE Inc, 1993, ISBN 1-55937-255-9.  File: zsh.info, Node: Invocation, Next: Files, Prev: Introduction, Up: Top Invocation ********** Invocation Options ================== The following flags are interpreted by the shell when invoked to determine where the shell will read commands from: -c Take the first argument as a command to execute, rather than reading commands from a script or standard input. If any further arguments are given, the first one is assigned to $0, rather than being used as a positional parameter. -i Force shell to be interactive. -s Force shell to read commands from the standard input. If the -s flag is not present and an argument is given, the first argument is taken to be the pathname of a script to execute. After the first one or two arguments have been appropriated as described above, the remaining arguments are assigned to the positional parameters. For further options, which are common to invocation and the set builtin, see *Note Options::. Options may be specified by name using the -o option. -o acts like a single-letter option, but takes a following string as the option name. For example, zsh -x -o shwordsplit scr runs the script scr, setting the XTRACE option by the corresponding letter `-x' and the SH_WORD_SPLIT option by name. Options may be turned _off_ by name by using +o instead of -o. -o can be stacked up with preceding single-letter options, so for example `-xo shwordsplit' or `-xoshwordsplit' is equivalent to `-x -o shwordsplit'. Options may also be specified by name in GNU long option style, `-OPTION-NAME'. When this is done, `-' characters in the option name are permitted: they are translated into `_', and thus ignored. So, for example, `zsh -sh-word-split' invokes zsh with the SH_WORD_SPLIT option turned on. Like other option syntaxes, options can be turned off by replacing the initial `-' with a `+'; thus `+-sh-word-split' is equivalent to `-no-sh-word-split'. Unlike other option syntaxes, GNU-style long options cannot be stacked with any other options, so for example `-x-shwordsplit' is an error, rather than being treated like `-x -shwordsplit'. The special GNU-style option `-version' is handled; it sends to standard output the shell's version information, then exits successfully. `-help' is also handled; it sends to standard output a list of options that can be used when invoking the shell, then exits successfully. Option processing may be finished, allowing following arguments that start with `-' or `+' to be treated as normal arguments, in two ways. Firstly, a lone `-' (or `+') as an argument by itself ends option processing. Secondly, a special option `-' (or `+-'), which may be specified on its own (which is the standard POSIX usage) or may be stacked with preceding options (so `-x-' is equivalent to `-x -'). Options are not permitted to be stacked after `-' (so `-x-f' is an error), but note the GNU-style option form discussed above, where `-shwordsplit' is permitted and does not end option processing. Except when the `sh'/`ksh' emulation single-letter options are in effect, the option `-b' (or `+b') ends option processing. `-b' is like `-', except that further single-letter options can be stacked after the `-b' and will take effect as normal. * Menu: * Compatibility:: * Restricted Shell::  File: zsh.info, Node: Compatibility, Next: Restricted Shell, Up: Invocation Compatibility ============= Zsh tries to emulate `sh' or `ksh' when it is invoked as sh or ksh respectively; more precisely, it looks at the first letter of the name by which it was invoked, excluding any initial `r' (assumed to stand for `restricted'), and if that is `s' or `k' it will emulate `sh' or `ksh'. Furthermore, if invoked as su (which happens on certain systems when the shell is executed by the su command), the shell will try to find an alternative name from the SHELL environment variable and perform emulation based on that. In `sh' and `ksh' compatibility modes the following parameters are not special and not initialized by the shell: ARGC, argv, cdpath, fignore, fpath, HISTCHARS, mailpath, MANPATH, manpath, path, prompt, PROMPT, PROMPT2, PROMPT3, PROMPT4, psvar, status, watch. The usual zsh startup/shutdown scripts are not executed. Login shells source /etc/profile followed by $HOME/.profile. If the ENV environment variable is set on invocation, $ENV is sourced after the profile scripts. The value of ENV is subjected to parameter expansion, command substitution, and arithmetic expansion before being interpreted as a pathname. Note that the PRIVILEGED option also affects the execution of startup files. The following options are set if the shell is invoked as sh or ksh: NO_BAD_PATTERN, NO_BANG_HIST, NO_BG_NICE, NO_EQUALS, NO_FUNCTION_ARGZERO, GLOB_SUBST, NO_GLOBAL_EXPORT, NO_HUP, INTERACTIVE_COMMENTS, KSH_ARRAYS, NO_MULTIOS, NO_NOMATCH, NO_NOTIFY, POSIX_BUILTINS, NO_PROMPT_PERCENT, RM_STAR_SILENT, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT. Additionally the BSD_ECHO and IGNORE_BRACES options are set if zsh is invoked as sh. Also, the KSH_OPTION_PRINT, LOCAL_OPTIONS, PROMPT_BANG, PROMPT_SUBST and SINGLE_LINE_ZLE options are set if zsh is invoked as ksh.  File: zsh.info, Node: Restricted Shell, Prev: Compatibility, Up: Invocation Restricted Shell ================ When the basename of the command used to invoke zsh starts with the letter `r' or the `-r' command line option is supplied at invocation, the shell becomes restricted. Emulation mode is determined after stripping the letter `r' from the invocation name. The following are disabled in restricted mode: * changing directories with the cd builtin * changing or unsetting the PATH, path, MODULE_PATH, module_path, SHELL, HISTFILE, HISTSIZE, GID, EGID, UID, EUID, USERNAME, LD_LIBRARY_PATH, LD_AOUT_LIBRARY_PATH, LD_PRELOAD and LD_AOUT_PRELOAD parameters * specifying command names containing / * specifying command pathnames using hash * redirecting output to files * using the exec builtin command to replace the shell with another command * using jobs -Z to overwrite the shell process' argument and environment space * using the ARGV0 parameter to override argv[0] for external commands * turning off restricted mode with set +r or unsetopt RESTRICTED These restrictions are enforced after processing the startup files. The startup files should set up PATH to point to a directory of commands which can be safely invoked in the restricted environment. They may also add further restrictions by disabling selected builtins. Restricted mode can also be activated any time by setting the RESTRICTED option. This immediately enables all the restrictions described above even if the shell still has not processed all startup files.  File: zsh.info, Node: Files, Next: Shell Grammar, Prev: Invocation, Up: Top Files ***** Startup/Shutdown Files ====================== Commands are first read from /etc/zshenv; this cannot be overridden. Subsequent behaviour is modified by the RCS and GLOBAL_RCS options; the former affects all startup files, while the second only affects those in the /etc directory. If one of the options is unset at any point, any subsequent startup file(s) of the corresponding type will not be read. It is also possible for a file in $ZDOTDIR to re-enable GLOBAL_RCS. Both RCS and GLOBAL_RCS are set by default. Commands are then read from $ZDOTDIR/.zshenv. If the shell is a login shell, commands are read from /etc/zprofile and then $ZDOTDIR/.zprofile. Then, if the shell is interactive, commands are read from /etc/zshrc and then $ZDOTDIR/.zshrc. Finally, if the shell is a login shell, /etc/zlogin and $ZDOTDIR/.zlogin are read. When a login shell exits, the files $ZDOTDIR/.zlogout and then /etc/zlogout are read. This happens with either an explicit exit via the exit or logout commands, or an implicit exit by reading end-of-file from the terminal. However, if the shell terminates due to exec'ing another process, the logout files are not read. These are also affected by the RCS and GLOBAL_RCS options. Note also that the RCS option affects the saving of history files, i.e. if RCS is unset when the shell exits, no history file will be saved. If ZDOTDIR is unset, HOME is used instead. Those files listed above as being in /etc may be in another directory, depending on the installation. As /etc/zshenv is run for all instances of zsh, it is important that it be kept as small as possible. In particular, it is a good idea to put code that does not need to be run for every single shell behind a test of the form `if [[ -o rcs ]]; then ...' so that it will not be executed when zsh is invoked with the `-f' option. Files ===== $ZDOTDIR/.zshenv $ZDOTDIR/.zprofile $ZDOTDIR/.zshrc $ZDOTDIR/.zlogin $ZDOTDIR/.zlogout ${TMPPREFIX}* (default is /tmp/zsh*) /etc/zshenv /etc/zprofile /etc/zshrc /etc/zlogin /etc/zlogout (installation-specific - /etc is the default) Any of these files may be pre-compiled with the zcompile builtin command (*Note Shell Builtin Commands::). If a compiled file exists (named for the original file plus the .zwc extension) and it is newer than the original file, the compiled file will be used instead.  File: zsh.info, Node: Shell Grammar, Next: Redirection, Prev: Files, Up: Top Shell Grammar ************* * Menu: * Simple Commands & Pipelines:: * Precommand Modifiers:: * Complex Commands:: * Alternate Forms For Complex Commands:: * Reserved Words:: * Comments:: * Aliasing:: * Quoting::  File: zsh.info, Node: Simple Commands & Pipelines, Next: Precommand Modifiers, Up: Shell Grammar Simple Commands & Pipelines =========================== A _simple command_ is a sequence of optional parameter assignments followed by blank-separated words, with optional redirections interspersed. The first word is the command to be executed, and the remaining words, if any, are arguments to the command. If a command name is given, the parameter assignments modify the environment of the command when it is executed. The value of a simple command is its exit status, or 128 plus the signal number if terminated by a signal. For example, echo foo is a simple command with arguments. A _pipeline_ is either a simple command, or a sequence of two or more simple commands where each command is separated from the next by `|' or `|&'. Where commands are separated by `|', the standard output of the first command is connected to the standard input of the next. `|&' is shorthand for `2>&1 |', which connects both the standard output and the standard error of the command to the standard input of the next. The value of a pipeline is the value of the last command, unless the pipeline is preceded by `!' in which case the value is the logical inverse of the value of the last command. For example, echo foo | sed 's/foo/bar/' is a pipeline, where the output (`foo' plus a newline) of the first command will be passed to the input of the second. If a pipeline is preceded by `coproc', it is executed as a coprocess; a two-way pipe is established between it and the parent shell. The shell can read from or write to the coprocess by means of the `>&p' and `<&p' redirection operators or with `print -p' and `read -p'. A pipeline cannot be preceded by both `coproc' and `!'. If job control is active, the coprocess can be treated in other than input and output as an ordinary background job. A _sublist_ is either a single pipeline, or a sequence of two or more pipelines separated by `&&' or `||'. If two pipelines are separated by `&&', the second pipeline is executed only if the first succeeds (returns a zero value). If two pipelines are separated by `||', the second is executed only if the first fails (returns a nonzero value). Both operators have equal precedence and are left associative. The value of the sublist is the value of the last pipeline executed. For example, dmesg | grep panic && print yes is a sublist consisting of two pipelines, the second just a simple command which will be executed if and only if the grep command returns a zero value. If it does not, the value of the sublist is that return value, else it is the value returned by the print (almost certainly zero). A _list_ is a sequence of zero or more sublists, in which each sublist is terminated by `;', `&', `&|', `&!', or a newline. This terminator may optionally be omitted from the last sublist in the list when the list appears as a complex command inside `(...)' or `{...}'. When a sublist is terminated by `;' or newline, the shell waits for it to finish before executing the next sublist. If a sublist is terminated by a `&', `&|', or `&!', the shell executes the last pipeline in it in the background, and does not wait for it to finish (note the difference from other shells which execute the whole sublist in the background). A backgrounded pipeline returns a status of zero. More generally, a list can be seen as a set of any shell commands whatsoever, including the complex commands below; this is implied wherever the word `list' appears in later descriptions. For example, the commands in a shell function form a special sort of list.  File: zsh.info, Node: Precommand Modifiers, Next: Complex Commands, Prev: Simple Commands & Pipelines, Up: Shell Grammar Precommand Modifiers ==================== A simple command may be preceded by a _precommand modifier_, which will alter how the command is interpreted. These modifiers are shell builtin commands with the exception of nocorrect which is a reserved word. - The command is executed with a `-' prepended to its argv[0] string. noglob Filename generation (globbing) is not performed on any of the words. nocorrect Spelling correction is not done on any of the words. This must appear before any other precommand modifier, as it is interpreted immediately, before any parsing is done. It has no effect in non-interactive shells. exec The command is executed in the parent shell without forking. command The command word is taken to be the name of an external command, rather than a shell function or builtin. builtin The command word is taken to be the name of a builtin command, rather than a shell function or external command.  File: zsh.info, Node: Complex Commands, Next: Alternate Forms For Complex Commands, Prev: Precommand Modifiers, Up: Shell Grammar Complex Commands ================ A _complex command_ in zsh is one of the following: if LIST then LIST [ elif LIST then LIST ] ... [ else LIST ] fi The if LIST is executed, and if it returns a zero exit status, the then LIST is executed. Otherwise, the elif LIST is executed and if its value is zero, the then LIST is executed. If each elif LIST returns nonzero, the else LIST is executed. for NAME ... [ in WORD ... ] TERM do LIST done where TERM is at least one newline or ;. Expand the list of WORDs, and set the parameter NAME to each of them in turn, executing LIST each time. If the in WORD is omitted, use the positional parameters instead of the WORDs. More than one parameter NAME can appear before the list of WORDs. If N NAMEs are given, then on each execution of the loop the next N WORDs are assigned to the corresponding parameters. If there are more NAMEs than remaining WORDs, the remaining parameters are each set to the empty string. Execution of the loop ends when there is no remaining WORD to assign to the first NAME. It is only possible for in to appear as the first NAME in the list, else it will be treated as marking the end of the list. for (( [EXPR1] ; [EXPR2] ; [EXPR3] )) do LIST done The arithmetic expression EXPR1 is evaluated first (see *Note Arithmetic Evaluation::). The arithmetic expression EXPR2 is repeatedly evaluated until it evaluates to zero and when non-zero, LIST is executed and the arithmetic expression EXPR3 evaluated. If any expression is omitted, then it behaves as if it evaluated to 1. while LIST do LIST done Execute the do LIST as long as the while LIST returns a zero exit status. until LIST do LIST done Execute the do LIST as long as until LIST returns a nonzero exit status. repeat WORD do LIST done WORD is expanded and treated as an arithmetic expression, which must evaluate to a number N. LIST is then executed N times. case WORD in [ [(] PATTERN [ | PATTERN ] ... ) LIST (;;|;&) ] ... esac Execute the LIST associated with the first PATTERN that matches WORD, if any. The form of the patterns is the same as that used for filename generation. See *Note Filename Generation::. If the LIST that is executed is terminated with ;& rather than ;;, the following list is also executed. This continues until either a list is terminated with ;; or the esac is reached. select NAME [ in WORD ... TERM ] do LIST done where TERM is one or more newline or ; to terminate the WORDs. Print the set of WORDs, each preceded by a number. If the in WORD is omitted, use the positional parameters. The PROMPT3 prompt is printed and a line is read from the line editor if the shell is interactive and that is active, or else standard input. If this line consists of the number of one of the listed WORDs, then the parameter NAME is set to the WORD corresponding to this number. If this line is empty, the selection list is printed again. Otherwise, the value of the parameter NAME is set to null. The contents of the line read from standard input is saved in the parameter REPLY. LIST is executed for each selection until a break or end-of-file is encountered. ( LIST ) Execute LIST in a subshell. Traps set by the trap builtin are reset to their default values while executing LIST. { LIST } Execute LIST. function WORD ... [ () ] [ TERM ] { LIST } WORD ... () [ TERM ] { LIST } WORD ... () [ TERM ] COMMAND where TERM is one or more newline or ;. Define a function which is referenced by any one of WORD. Normally, only one WORD is provided; multiple WORDs are usually only useful for setting traps. The body of the function is the LIST between the { and }. See *Note Functions::. If the option SH_GLOB is set for compatibility with other shells, then whitespace may appear between between the left and right parentheses when there is a single WORD; otherwise, the parentheses will be treated as forming a globbing pattern in that case. time [ PIPELINE ] The PIPELINE is executed, and timing statistics are reported on the standard error in the form specified by the TIMEFMT parameter. If PIPELINE is omitted, print statistics about the shell process and its children. [[ EXP ]] Evaluates the conditional expression EXP and return a zero exit status if it is true. See *Note Conditional Expressions:: for a description of EXP.  File: zsh.info, Node: Alternate Forms For Complex Commands, Next: Reserved Words, Prev: Complex Commands, Up: Shell Grammar Alternate Forms For Complex Commands ==================================== Many of zsh's complex commands have alternate forms. These particular versions of complex commands should be considered deprecated and may be removed in the future. The versions in the previous section should be preferred instead. The short versions below only work if SUBLIST is of the form `{ LIST }' or if the SHORT_LOOPS option is set. For the if, while and until commands, in both these cases the test part of the loop must also be suitably delimited, such as by `[[ ... ]]' or `(( ... ))', else the end of the test will not be recognized. For the for, repeat, case and select commands no such special form for the arguments is necessary, but the other condition (the special form of SUBLIST or use of the SHORT_LOOPS option) still applies. if LIST { LIST } [ elif LIST { LIST } ] ... [ else { LIST } ] An alternate form of if. The rules mean that if [[ -o ignorebraces ]] { print yes } works, but if true { # Does not work! print yes } does _not_, since the test is not suitably delimited. if LIST SUBLIST A short form of the alternate `if'. The same limitations on the form of LIST apply as for the previous form. for NAME ... ( WORD ... ) SUBLIST A short form of for. for NAME ... [ in WORD ... ] TERM SUBLIST where TERM is at least one newline or ;. Another short form of for. for (( [EXPR1] ; [EXPR2] ; [EXPR3] )) SUBLIST A short form of the arithmetic for command. foreach NAME ... ( WORD ... ) LIST end Another form of for. while LIST { LIST } An alternative form of while. Note the limitations on the form of LIST mentioned above. until LIST { LIST } An alternative form of until. Note the limitations on the form of LIST mentioned above. repeat WORD SUBLIST This is a short form of repeat. case WORD { [ [(] PATTERN [ | PATTERN ] ... ) LIST (;;|;&) ] ... } An alternative form of case. select NAME [ in WORD TERM ] SUBLIST where TERM is at least one newline or ;. A short form of select.  File: zsh.info, Node: Reserved Words, Next: Comments, Prev: Alternate Forms For Complex Commands, Up: Shell Grammar Reserved Words ============== The following words are recognized as reserved words when used as the first word of a command unless quoted or disabled using disable -r: do done esac then elif else fi for case if while function repeat time until select coproc nocorrect foreach end ! [[ { } Additionally, `}' is recognized in any position if the IGNORE_BRACES option is not set.  File: zsh.info, Node: Comments, Next: Aliasing, Prev: Reserved Words, Up: Shell Grammar Comments ======== In noninteractive shells, or in interactive shells with the INTERACTIVE_COMMENTS option set, a word beginning with the third character of the histchars parameter (`#' by default) causes that word and all the following characters up to a newline to be ignored.  File: zsh.info, Node: Aliasing, Next: Quoting, Prev: Comments, Up: Shell Grammar Aliasing ======== Every token in the shell input is checked to see if there is an alias defined for it. If so, it is replaced by the text of the alias if it is in command position (if it could be the first word of a simple command), or if the alias is global. If the text ends with a space, the next word in the shell input is treated as though it were in command position for purposes of alias expansion. An alias is defined using the alias builtin; global aliases may be defined using the -g option to that builtin. Alias expansion is done on the shell input before any other expansion except history expansion. Therefore, if an alias is defined for the word foo, alias expansion may be avoided by quoting part of the word, e.g. \foo. But there is nothing to prevent an alias being defined for \foo as well.  File: zsh.info, Node: Quoting, Prev: Aliasing, Up: Shell Grammar Quoting ======= A character may be QUOTED (that is, made to stand for itself) by preceding it with a `\'. `\' followed by a newline is ignored. A string enclosed between `$'' and `'' is processed the same way as the string arguments of the print builtin, and the resulting string is considered to be entirely quoted. A literal `'' character can be included in the string by using the `\'' escape. All characters enclosed between a pair of single quotes ('') that is not preceded by a `$' are quoted. A single quote cannot appear within single quotes unless the option RC_QUOTES is set, in which case a pair of single quotes are turned into a single quote. For example, print '''' outputs nothing apart from a newline if RC_QUOTES is not set, but one single quote if it is set. Inside double quotes (""), parameter and command substitution occur, and `\' quotes the characters `\', ``', `"', and `$'.  File: zsh.info, Node: Redirection, Next: Command Execution, Prev: Shell Grammar, Up: Top Redirection *********** If a command is followed by & and job control is not active, then the default standard input for the command is the empty file /dev/null. Otherwise, the environment for the execution of a command contains the file descriptors of the invoking shell as modified by input/output specifications. The following may appear anywhere in a simple command or may precede or follow a complex command. Expansion occurs before WORD or DIGIT is used except as noted below. If the result of substitution on WORD produces more than one filename, redirection occurs for each separate filename in turn. < WORD Open file WORD for reading as standard input. <> WORD Open file WORD for reading and writing as standard input. If the file does not exist then it is created. > WORD Open file WORD for writing as standard output. If the file does not exist then it is created. If the file exists, and the CLOBBER option is unset, this causes an error; otherwise, it is truncated to zero length. >| WORD >! WORD Same as >, except that the file is truncated to zero length if it exists, even if CLOBBER is unset. >> WORD Open file WORD for writing in append mode as standard output. If the file does not exist, and the CLOBBER option is unset, this causes an error; otherwise, the file is created. >>| WORD >>! WORD Same as >>, except that the file is created if it does not exist, even if CLOBBER is unset. <<[-] WORD The shell input is read up to a line that is the same as WORD, or to an end-of-file. No parameter expansion, command substitution or filename generation is performed on WORD. The resulting document, called a _here-document_, becomes the standard input. If any character of WORD is quoted with single or double quotes or a `\', no interpretation is placed upon the characters of the document. Otherwise, parameter and command substitution occurs, `\' followed by a newline is removed, and `\' must be used to quote the characters `\', `$', ``' and the first character of WORD. If <<- is used, then all leading tabs are stripped from WORD and from the document. <<< WORD Perform shell expansion on WORD and pass the result to standard input. This is known as a _here-string_. <& NUMBER >& NUMBER The standard input/output is duplicated from file descriptor NUMBER (see man page dup2(2)). <& - >& - Close the standard input/output. <& p >& p The input/output from/to the coprocess is moved to the standard input/output. >& WORD &> WORD (Except where `>& WORD' matches one of the above syntaxes; `&>' can always be used to avoid this ambiguity.) Redirects both standard output and standard error (file descriptor 2) in the manner of `> WORD'. Note that this does _not_ have the same effect as `> WORD 2>&1' in the presence of multios (see the section below). >&| WORD >&! WORD &>| WORD &>! WORD Redirects both standard output and standard error (file descriptor 2) in the manner of `>| WORD'. >>& WORD &>> WORD Redirects both standard output and standard error (file descriptor 2) in the manner of `>> WORD'. >>&| WORD >>&! WORD &>>| WORD &>>! WORD Redirects both standard output and standard error (file descriptor 2) in the manner of `>>| WORD'. If one of the above is preceded by a digit, then the file descriptor referred to is that specified by the digit instead of the default 0 or 1. The order in which redirections are specified is significant. The shell evaluates each redirection in terms of the (_file descriptor_, _file_) association at the time of evaluation. For example: ... 1>FNAME 2>&1 first associates file descriptor 1 with file FNAME. It then associates file descriptor 2 with the file associated with file descriptor 1 (that is, FNAME). If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and then file descriptor 1 would be associated with file FNAME. The `|&' command separator described in *Note Simple Commands & Pipelines:: is a shorthand for `2>&1 |'. For output redirections only, if WORD is of the form `>(LIST)' then the output is piped to the command represented by LIST. See *Note Process Substitution::. Multios ======= If the user tries to open a file descriptor for writing more than once, the shell opens the file descriptor as a pipe to a process that copies its input to all the specified outputs, similar to `tee', provided the MULTIOS option is set, as it is by default. Thus: date >foo >bar writes the date to two files, named `foo' and `bar'. Note that a pipe is an implicit redirection; thus date >foo | cat writes the date to the file `foo', and also pipes it to cat. If the MULTIOS option is set, the word after a redirection operator is also subjected to filename generation (globbing). Thus : > * will truncate all files in the current directory, assuming there's at least one. (Without the MULTIOS option, it would create an empty file called `*'.) Similarly, you can do echo exit 0 >> *.sh If the user tries to open a file descriptor for reading more than once, the shell opens the file descriptor as a pipe to a process that copies all the specified inputs to its output in the order specified, similar to `cat', provided the MULTIOS option is set. Thus sort bar > baz when MULTIOS is unset will truncate bar, and write `foo' into baz. There is a problem when an output multio is attached to an external program. A simple example shows this: cat file >file1 >file2 cat file1 file2 Here, it is possible that the second `cat' will not display the full contents of file1 and file2 (i.e. the original contents of file repeated twice). The reason for this is that the multios are spawned after the cat process is forked from the parent shell, so the parent shell does not wait for the multios to finish writing data. This means the command as shown can exit before file1 and file2 are completely written. As a workaround, it is possible to run the cat process as part of a job in the current shell: { cat file } >file >file2 Here, the {...} job will pause to wait for both files to be written. Redirections with no command ============================ When a simple command consists of one or more redirection operators and zero or more parameter assignments, but no command name, zsh can behave in several ways. If the parameter NULLCMD is not set or the option CSH_NULLCMD is set, an error is caused. This is the `csh' behavior and CSH_NULLCMD is set by default when emulating `csh'. If the option SH_NULLCMD is set, the builtin `:' is inserted as a command with the given redirections. This is the default when emulating `sh' or `ksh'. Otherwise, if the parameter NULLCMD is set, its value will be used as a command with the given redirections. If both NULLCMD and READNULLCMD are set, then the value of the latter will be used instead of that of the former when the redirection is an input. The default for NULLCMD is `cat' and for READNULLCMD is `more'. Thus < file shows the contents of file on standard output, with paging if that is a terminal. NULLCMD and READNULLCMD may refer to shell functions.  File: zsh.info, Node: Command Execution, Next: Functions, Prev: Redirection, Up: Top Command Execution ***************** If a command name contains no slashes, the shell attempts to locate it. If there exists a shell function by that name, the function is invoked as described in *Note Functions::. If there exists a shell builtin by that name, the builtin is invoked. Otherwise, the shell searches each element of $path for a directory containing an executable file by that name. If the search is unsuccessful, the shell prints an error message and returns a nonzero exit status. If execution fails because the file is not in executable format, and the file is not a directory, it is assumed to be a shell script. /bin/sh is spawned to execute it. If the program is a file beginning with `#!', the remainder of the first line specifies an interpreter for the program. The shell will execute the specified interpreter on operating systems that do not handle this executable format in the kernel.  File: zsh.info, Node: Functions, Next: Jobs & Signals, Prev: Command Execution, Up: Top Functions ********* Shell functions are defined with the function reserved word or the special syntax `FUNCNAME ()'. Shell functions are read in and stored internally. Alias names are resolved when the function is read. Functions are executed like commands with the arguments passed as positional parameters. (See *Note Command Execution::.) Functions execute in the same process as the caller and share all files and present working directory with the caller. A trap on EXIT set inside a function is executed after the function completes in the environment of the caller. The return builtin is used to return from function calls. Function identifiers can be listed with the functions builtin. Functions can be undefined with the unfunction builtin. Autoloading Functions ===================== A function can be marked as _undefined_ using the autoload builtin (or `functions -u' or `typeset -fu'). Such a function has no body. When the function is first executed, the shell searches for its definition using the elements of the fpath variable. Thus to define functions for autoloading, a typical sequence is: fpath=(~/myfuncs $fpath) autoload myfunc1 myfunc2 ... The usual alias expansion during reading will be suppressed if the autoload builtin or its equivalent is given the option -U. This is recommended for the use of functions supplied with the zsh distribution. Note that for functions precompiled with the zcompile builtin command the flag -U must be provided when the .zwc file is created, as the corresponding information is compiled into the latter. For each ELEMENT in fpath, the shell looks for three possible files, the newest of which is used to load the definition for the function: ELEMENT.zwc A file created with the zcompile builtin command, which is expected to contain the definitions for all functions in the directory named ELEMENT. The file is treated in the same manner as a directory containing files for functions and is searched for the definition of the function. If the definition is not found, the search for a definition proceeds with the other two possibilities described below. If ELEMENT already includes a .zwc extension (i.e. the extension was explicitly given by the user), ELEMENT is searched for the definition of the function without comparing its age to that of other files; in fact, there does not need to be any directory named ELEMENT without the suffix. Thus including an element such as `/usr/local/funcs.zwc' in fpath will speed up the search for functions, with the disadvantage that functions included must be explicitly recompiled by hand before the shell notices any changes. ELEMENT/FUNCTION.zwc A file created with zcompile, which is expected to contain the definition for FUNCTION. It may include other function definitions as well, but those are neither loaded nor executed; a file found in this way is searched _only_ for the definition of FUNCTION. ELEMENT/FUNCTION A file of zsh command text, taken to be the definition for FUNCTION. In summary, the order of searching is, first, in the _parents of_ directories in fpath for the newer of either a compiled directory or a directory in fpath; second, if more than one of these contains a definition for the function that is sought, the leftmost in the fpath is chosen; and third, within a directory, the newer of either a compiled function or an ordinary function definition is used. If the KSH_AUTOLOAD option is set, or the file contains only a simple definition of the function, the file's contents will be executed. This will normally define the function in question, but may also perform initialization, which is executed in the context of the function execution, and may therefore define local parameters. It is an error if the function is not defined by loading the file. Otherwise, the function body (with no surrounding `FUNCNAME() {...}') is taken to be the complete contents of the file. This form allows the file to be used directly as an executable shell script. If processing of the file results in the function being re-defined, the function itself is not re-executed. To force the shell to perform initialization and then call the function defined, the file should contain initialization code (which will be executed then discarded) in addition to a complete function definition (which will be retained for subsequent calls to the function), and a call to the shell function, including any arguments, at the end. For example, suppose the autoload file func contains func() { print This is func; } print func is initialized then `func; func' with KSH_AUTOLOAD set will produce both messages on the first call, but only the message `This is func' on the second and subsequent calls. Without KSH_AUTOLOAD set, it will produce the initialization message on the first call, and the other message on the second and subsequent calls. It is also possible to create a function that is not marked as autoloaded, but which loads its own definition by searching fpath, by using `autoload -X' within a shell function. For example, the following are equivalent: myfunc() { autoload -X } myfunc args... and unfunction myfunc # if myfunc was defined autoload myfunc myfunc args... In fact, the functions command outputs `builtin autoload -X' as the body of an autoloaded function. This is done so that eval "$(functions)" produces a reasonable result. A true autoloaded function can be identified by the presence of the comment `# undefined' in the body, because all comments are discarded from defined functions. To load the definition of an autoloaded function myfunc without executing myfunc, use: autoload +X myfunc Special Functions ================= The following functions, if defined, have special meaning to the shell: chpwd Executed whenever the current working directory is changed. periodic If the parameter PERIOD is set, this function is executed every $PERIOD seconds, just before a prompt. precmd Executed before each prompt. preexec Executed just after a command has been read and is about to be executed. If the history mechanism is active (and the line was not discarded from the history buffer), the string that the user typed is passed as the first argument, otherwise it is an empty string. The actual command that will be executed (including expanded aliases) is passed in two different forms: the second argument is a single-line, size-limited version of the command (with things like function bodies elided); the third argument contains the full text that is being executed. TRAPNAL If defined and non-null, this function will be executed whenever the shell catches a signal SIGNAL, where NAL is a signal name as specified for the kill builtin. The signal number will be passed as the first parameter to the function. If a function of this form is defined and null, the shell and processes spawned by it will ignore SIGNAL. TRAPDEBUG Executed after each command. TRAPEXIT Executed when the shell exits, or when the current function exits if defined inside a function. TRAPZERR Executed whenever a command has a non-zero exit status. However, the function is not executed if the command occurred in a sublist followed by `&&' or `||'; only the final command in a sublist of this type causes the trap to be executed. The functions beginning `TRAP' may alternatively be defined with the trap builtin: this may be preferable for some uses, as they are then run in the environment of the calling process, rather than in their own function environment. Apart from the difference in calling procedure and the fact that the function form appears in lists of functions, the forms TRAPNAL() { # code } and trap ' # code ' NAL are equivalent.  File: zsh.info, Node: Jobs & Signals, Next: Arithmetic Evaluation, Prev: Functions, Up: Top Jobs & Signals ************** Jobs ==== If the MONITOR option is set, an interactive shell associates a _job_ with each pipeline. It keeps a table of current jobs, printed by the jobs command, and assigns them small integer numbers. When a job is started asynchronously with `&', the shell prints a line which looks like: [1] 1234 indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process ID was 1234. If a job is started with `&|' or `&!', then that job is immediately disowned. After startup, it does not have a place in the job table, and is not subject to the job control features described here. If you are running a job and wish to do something else you may hit the key ^Z (control-Z) which sends a TSTP signal to the current job: this key may be redefined by the susp option of the external stty command. The shell will then normally indicate that the job has been `suspended', and print another prompt. You can then manipulate the state of this job, putting it in the background with the bg command, or run some other commands and then eventually bring the job back into the foreground with the foreground command fg. A ^Z takes effect immediately and is like an interrupt in that pending output and unread input are discarded when it is typed. A job being run in the background will suspend if it tries to read from the terminal. Background jobs are normally allowed to produce output, but this can be disabled by giving the command `stty tostop'. If you set this tty option, then background jobs will suspend when they try to produce output like they do when they try to read input. When a command is suspended and continued later with the fg or wait builtins, zsh restores tty modes that were in effect when it was suspended. This (intentionally) does not apply if the command is continued via `kill -CONT', nor when it is continued with bg. There are several ways to refer to jobs in the shell. A job can be referred to by the process ID of any process of the job or by one of the following: %NUMBER The job with the given number. %STRING Any job whose command line begins with STRING. %?STRING Any job whose command line contains STRING. %% Current job. %+ Equivalent to `%%'. %- Previous job. The shell learns immediately whenever a process changes state. It normally informs you whenever a job becomes blocked so that no further progress is possible. If the NOTIFY option is not set, it waits until just before it prints a prompt before it informs you. When the monitor mode is on, each background job that completes triggers any trap set for CHLD. When you try to leave the shell while jobs are running or suspended, you will be warned that `You have suspended (running) jobs'. You may use the jobs command to see what they are. If you do this or immediately try to exit again, the shell will not warn you a second time; the suspended jobs will be terminated, and the running jobs will be sent a SIGHUP signal, if the HUP option is set. To avoid having the shell terminate the running jobs, either use the `nohup' command (see man page nohup(1)) or the disown builtin. Signals ======= The INT and QUIT signals for an invoked command are ignored if the command is followed by `&' and the MONITOR option is not active. Otherwise, signals have the values inherited by the shell from its parent (but see the TRAPNAL special functions in *Note Functions::).  File: zsh.info, Node: Arithmetic Evaluation, Next: Conditional Expressions, Prev: Jobs & Signals, Up: Top Arithmetic Evaluation ********************* The shell can perform integer and floating point arithmetic, either using the builtin let, or via a substitution of the form $((...)). For integers, the shell is usually compiled to use 8-byte precision where this is available, otherwise precision is 4 bytes. This can be tested, for example, by giving the command `print - $(( 12345678901 ))'; if the number appears unchanged, the precision is at least 8 bytes. Floating point arithmetic is always double precision. The let builtin command takes arithmetic expressions as arguments; each is evaluated separately. Since many of the arithmetic operators, as well as spaces, require quoting, an alternative form is provided: for any command which begins with a `((', all the characters until a matching `))' are treated as a quoted expression and arithmetic expansion performed as for an argument of let. More precisely, `((...))' is equivalent to `let "..."'. For example, the following statement (( val = 2 + 1 )) is equivalent to let "val = 2 + 1" both assigning the value 3 to the shell variable val and returning a zero status. Integers can be in bases other than 10. A leading `0x' or `0X' denotes hexadecimal. Integers may also be of the form `BASE#N', where BASE is a decimal number between two and thirty-six representing the arithmetic base and N is a number in that base (for example, `16#ff' is 255 in hexadecimal). The BASE# may also be omitted, in which case base 10 is used. For backwards compatibility the form `[BASE]N' is also accepted. It is also possible to specify a base to be used for output in the form `[#BASE]', for example `[#16]'. This is used when outputting arithmetical substitutions or when assigning to scalar parameters, but an explicitly defined integer or floating point parameter will not be affected. If an integer variable is implicitly defined by an arithmetic expression, any base specified in this way will be set as the variable's output arithmetic base as if the option `-i BASE' to the typeset builtin had been used. The expression has no precedence and if it occurs more than once in a mathematical expression, the last encountered is used. For clarity it is recommended that it appear at the beginning of an expression. As an example: typeset -i 16 y print $(( [#8] x = 32, y = 32 )) print $x $y outputs first `8#40', the rightmost value in the given output base, and then `8#40 16#20', because y has been explicitly declared to have output base 16, while x (assuming it does not already exist) is implicitly typed by the arithmetic evaluation, where it acquires the output base 8. If the C_BASES option is set, hexadecimal numbers in the standard C format, for example 0xFF instead of the usual `16#FF'. If the option OCTAL_ZEROES is also set (it is not by default), octal numbers will be treated similarly and hence appear as `077' instead of `8#77'. This option has no effect on the output of bases other than hexadecimal and octal, and these formats are always understood on input. When an output base is specified using the `[#BASE]' syntax, an appropriate base prefix will be output if necessary, so that the value output is valid syntax for input. If the # is doubled, for example `[##16]', then no base prefix is output. Floating point constants are recognized by the presence of a decimal point or an exponent. The decimal point may be the first character of the constant, but the exponent character e or E may not, as it will be taken for a parameter name. An arithmetic expression uses nearly the same syntax, precedence, and associativity of expressions in C. The following operators are supported (listed in decreasing order of precedence): + - ! ~ ++ - unary plus/minus, logical NOT, complement, {pre,post}{in,de}crement << >> bitwise shift left, right & bitwise AND ^ bitwise XOR | bitwise OR ** exponentiation * / % multiplication, division, modulus (remainder) + - addition, subtraction < > <= >= comparison == != equality and inequality && logical AND || ^^ logical OR, XOR ? : ternary operator = += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **= assignment , comma operator The operators `&&', `||', `&&=', and `||=' are short-circuiting, and only one of the latter two expressions in a ternary operator is evaluated. Note the precedence of the bitwise AND, OR, and XOR operators. Mathematical functions can be called with the syntax `FUNC(ARGS)', where the function decides if the ARGS is used as a string or a comma-separated list of arithmetic expressions. The shell currently defines no mathematical functions by default, but the module zsh/mathfunc may be loaded with the zmodload builtin to provide standard floating point mathematical functions. An expression of the form `##X' where X is any character sequence such as `a', `^A', or `\M-\C-x' gives the ASCII value of this character and an expression of the form `#FOO' gives the ASCII value of the first character of the value of the parameter FOO. Note that this is different from the expression `$#FOO', a standard parameter substitution which gives the length of the parameter FOO. `#\' is accepted instead of `##', but its use is deprecated. Named parameters and subscripted arrays can be referenced by name within an arithmetic expression without using the parameter expansion syntax. For example, ((val2 = val1 * 2)) assigns twice the value of $val1 to the parameter named val2. An internal integer representation of a named parameter can be specified with the integer builtin. Arithmetic evaluation is performed on the value of each assignment to a named parameter declared integer in this manner. Assigning a floating point number to an integer results in rounding down to the next integer. Likewise, floating point numbers can be declared with the float builtin; there are two types, differing only in their output format, as described for the typeset builtin. The output format can be bypassed by using arithmetic substitution instead of the parameter substitution, i.e. `${FLOAT}' uses the defined format, but `$((FLOAT))' uses a generic floating point format. Promotion of integer to floating point values is performed where necessary. In addition, if any operator which requires an integer (`~', `&', `|', `^', `%', `<<', `>>' and their equivalents with assignment) is given a floating point argument, it will be silently rounded down to the next integer. Scalar variables can hold integer or floating point values at different times; there is no memory of the numeric type in this case. If a variable is first assigned in a numeric context without previously being declared, it will be implicitly typed as integer or float and retain that type either until the type is explicitly changed or until the end of the scope. This can have unforeseen consequences. For example, in the loop for (( f = 0; f < 1; f += 0.1 )); do # use $f done if f has not already been declared, the first assignment will cause it to be created as an integer, and consequently the operation `f += 0.1' will always cause the result to be truncated to zero, so that the loop will fail. A simple fix would be to turn the initialization into `f = 0.0'. It is therefore best to declare numeric variables with explicit types.  File: zsh.info, Node: Conditional Expressions, Next: Prompt Expansion, Prev: Arithmetic Evaluation, Up: Top Conditional Expressions *********************** A _conditional expression_ is used with the [[ compound command to test attributes of files and to compare strings. Each expression can be constructed from one or more of the following unary or binary expressions: -a FILE true if FILE exists. -b FILE true if FILE exists and is a block special file. -c FILE true if FILE exists and is a character special file. -d FILE true if FILE exists and is a directory. -e FILE true if FILE exists. -f FILE true if FILE exists and is a regular file. -g FILE true if FILE exists and has its setgid bit set. -h FILE true if FILE exists and is a symbolic link. -k FILE true if FILE exists and has its sticky bit set. -n STRING true if length of STRING is non-zero. -o OPTION true if option named OPTION is on. OPTION may be a single character, in which case it is a single letter option name. (See *Note Specifying Options::.) -p FILE true if FILE exists and is a FIFO special file (named pipe). -r FILE true if FILE exists and is readable by current process. -s FILE true if FILE exists and has size greater than zero. -t FD true if file descriptor number FD is open and associated with a terminal device. (note: FD is not optional) -u FILE true if FILE exists and has its setuid bit set. -w FILE true if FILE exists and is writable by current process. -x FILE true if FILE exists and is executable by current process. If FILE exists and is a directory, then the current process has permission to search in the directory. -z STRING true if length of STRING is zero. -L FILE true if FILE exists and is a symbolic link. -O FILE true if FILE exists and is owned by the effective user ID of this process. -G FILE true if FILE exists and its group matches the effective group ID of this process. -S FILE true if FILE exists and is a socket. -N FILE true if FILE exists and its access time is not newer than its modification time. FILE1 -nt FILE2 true if FILE1 exists and is newer than FILE2. FILE1 -ot FILE2 true if FILE1 exists and is older than FILE2. FILE1 -ef FILE2 true if FILE1 and FILE2 exist and refer to the same file. STRING = PATTERN STRING == PATTERN true if STRING matches PATTERN. The `==' form is the preferred one. The `=' form is for backward compatibility and should be considered obsolete. STRING != PATTERN true if STRING does not match PATTERN. STRING1 < STRING2 true if STRING1 comes before STRING2 based on ASCII value of their characters. STRING1 > STRING2 true if STRING1 comes after STRING2 based on ASCII value of their characters. EXP1 -eq EXP2 true if EXP1 is numerically equal to EXP2. EXP1 -ne EXP2 true if EXP1 is numerically not equal to EXP2. EXP1 -lt EXP2 true if EXP1 is numerically less than EXP2. EXP1 -gt EXP2 true if EXP1 is numerically greater than EXP2. EXP1 -le EXP2 true if EXP1 is numerically less than or equal to EXP2. EXP1 -ge EXP2 true if EXP1 is numerically greater than or equal to EXP2. ( EXP ) true if EXP is true. ! EXP true if EXP is false. EXP1 && EXP2 true if EXP1 and EXP2 are both true. EXP1 || EXP2 true if either EXP1 or EXP2 is true. Normal shell expansion is performed on the FILE, STRING and PATTERN arguments, but the result of each expansion is constrained to be a single word, similar to the effect of double quotes. However, pattern metacharacters are active for the PATTERN arguments; the patterns are the same as those used for filename generation, see *Note Filename Generation::, but there is no special behaviour of `/' nor initial dots, and no glob qualifiers are allowed. In each of the above expressions, if FILE is of the form `/dev/fd/N', where N is an integer, then the test applied to the open file whose descriptor number is N, even if the underlying system does not support the /dev/fd directory. In the forms which do numeric comparison, the expressions EXP undergo arithmetic expansion as if they were enclosed in $((...)). For example, the following: [[ ( -f foo || -f bar ) && $report = y* ]] && print File exists. tests if either file foo or file bar exists, and if so, if the value of the parameter report begins with `y'; if the complete condition is true, the message `File exists.' is printed.  File: zsh.info, Node: Prompt Expansion, Next: Expansion, Prev: Conditional Expressions, Up: Top Prompt Expansion **************** Prompt sequences undergo a special form of expansion. This type of expansion is also available using the -P option to the print builtin. If the PROMPT_SUBST option is set, the prompt string is first subjected to _parameter expansion_, _command substitution_ and _arithmetic expansion_. See *Note Expansion::. Certain escape sequences may be recognised in the prompt string. If the PROMPT_BANG option is set, a `!' in the prompt is replaced by the current history event number. A literal `!' may then be represented as `!!'. If the PROMPT_PERCENT option is set, certain escape sequences that start with `%' are expanded. Some escapes take an optional integer argument, which should appear between the `%' and the next character of the sequence. The following escape sequences are recognized: Special characters ------------------ %% A `%'. %) A `)'. Login information ----------------- %l The line (tty) the user is logged in on, without `/dev/' prefix. If the name starts with `/dev/tty', that prefix is stripped. %M The full machine hostname. %m The hostname up to the first `.'. An integer may follow the `%' to specify how many components of the hostname are desired. With a negative integer, trailing components of the hostname are shown. %n $USERNAME. %y The line (tty) the user is logged in on, without `/dev/' prefix. This does not treat `/dev/tty' names specially. Shell state ----------- %# A `#' if the shell is running with privileges, a `%' if not. Equivalent to `%(!.#.%%)'. The definition of `privileged', for these purposes, is that either the effective user ID is zero, or, if POSIX.1e capabilities are supported, that at least one capability is raised in either the Effective or Inheritable capability vectors. %? The return code of the last command executed just before the prompt. %_ The status of the parser, i.e. the shell constructs (like `if' and `for') that have been started on the command line. If given an integer number that many strings will be printed; zero or negative or no integer means print as many as there are. This is most useful in prompts PS2 for continuation lines and PS4 for debugging with the XTRACE option; in the latter case it will also work non-interactively. %d %/ Present working directory ($PWD). If an integer follows the `%', it specifies a number of trailing components of $PWD to show; zero means the whole path. A negative integer specifies leading components, i.e. %-1d specifies the first component. %~ As %d and %/, but if $PWD has a named directory as its prefix, that part is replaced by a `~' followed by the name of the directory. If it starts with $HOME, that part is replaced by a `~'. %h %! Current history event number. %i The line number currently being executed in the script, sourced file, or shell function given by %N. This is most useful for debugging as part of $PS4. %j The number of jobs. %L The current value of $SHLVL. %N The name of the script, sourced file, or shell function that zsh is currently executing, whichever was started most recently. If there is none, this is equivalent to the parameter $0. An integer may follow the `%' to specify a number of trailing path components to show; zero means the full path. A negative integer specifies leading components. %c %. %C Trailing component of $PWD. An integer may follow the `%' to get more than one component. Unless `%C' is used, tilde contraction is performed first. These are deprecated as %c and %C are equivalent to %1~ and %1/, respectively, while explicit positive integers have the same effect as for the latter two sequences. Date and time ------------- %D The date in YY-MM-DD format. %T Current time of day, in 24-hour format. %t %@ Current time of day, in 12-hour, am/pm format. %* Current time of day in 24-hour format, with seconds. %w The date in DAY-DD format. %W The date in MM/DD/YY format. %D{STRING} STRING is formatted using the strftime function. See man page strftime(3) for more details. Three additional codes are available: %f prints the day of the month, like %e but without any preceding space if the day is a single digit, and %K/%L correspond to %k/%l for the hour of the day (24/12 hour clock) in the same way. Visual effects -------------- %B (%b) Start (stop) boldface mode. %E Clear to end of line. %U (%u) Start (stop) underline mode. %S (%s) Start (stop) standout mode. %{...%} Include a string as a literal escape sequence. The string within the braces should not change the cursor position. Brace pairs can nest. Conditional substrings ---------------------- %v The value of the first element of the psvar array parameter. Following the `%' with an integer gives that element of the array. Negative integers count from the end of the array. %(X.TRUE-TEXT.FALSE-TEXT) Specifies a ternary expression. The character following the X is arbitrary; the same character is used to separate the text for the `true' result from that for the `false' result. This separator may not appear in the TRUE-TEXT, except as part of a %-escape sequence. A `)' may appear in the FALSE-TEXT as `%)'. TRUE-TEXT and FALSE-TEXT may both contain arbitrarily-nested escape sequences, including further ternary expressions. The left parenthesis may be preceded or followed by a positive integer N, which defaults to zero. A negative integer will be multiplied by -1. The test character X may be any of the following: ! True if the shell is running with privileges. # True if the effective uid of the current process is N. ? True if the exit status of the last command was N. _ True if at least N shell constructs were started. C / True if the current absolute path has at least N elements. c . ~ True if the current path, with prefix replacement, has at least N elements. D True if the month is equal to N (January = 0). d True if the day of the month is equal to N. g True if the effective gid of the current process is N. j True if the number of jobs is at least N. L True if the SHLVL parameter is at least N. l True if at least N characters have already been printed on the current line. S True if the SECONDS parameter is at least N. T True if the time in hours is equal to N. t True if the time in minutes is equal to N. v True if the array psvar has at least N elements. w True if the day of the week is equal to N (Sunday = 0). %STRING> %[XSTRING] Specifies truncation behaviour for the remainder of the prompt string. The third, deprecated, form is equivalent to `%XSTRINGX', i.e. X may be `<' or `>'. The numeric argument, which in the third form may appear immediately after the `[', specifies the maximum permitted length of the various strings that can be displayed in the prompt. The STRING will be displayed in place of the truncated portion of any string; note this does not undergo prompt expansion. The forms with `<' truncate at the left of the string, and the forms with `>' truncate at the right of the string. For example, if the current directory is `/home/pike', the prompt `%8<..<%/' will expand to `..e/pike'. In this string, the terminating character (`<', `>' or `]'), or in fact any character, may be quoted by a preceding `\'; note when using print -P, however, that this must be doubled as the string is also subject to standard print processing, in addition to any backslashes removed by a double quoted string: the worst case is therefore `print -P "%<\\\\<<..."'. If the STRING is longer than the specified truncation length, it will appear in full, completely replacing the truncated string. The part of the prompt string to be truncated runs to the end of the string, or to the end of the next enclosing group of the `%(' construct, or to the next truncation encountered at the same grouping level (i.e. truncations inside a `%(' are separate), which ever comes first. In particular, a truncation with argument zero (e.g. `%<<') marks the end of the range of the string to be truncated while turning off truncation from there on. For example, the prompt '%10<...<%~%<<%# ' will print a truncated representation of the current directory, followed by a `%' or `#', followed by a space. Without the `%<<', those two characters would be included in the string to be truncated.  File: zsh.info, Node: Expansion, Next: Parameters, Prev: Prompt Expansion, Up: Top Expansion ********* The following types of expansions are performed in the indicated order in five steps: _History Expansion_ This is performed only in interactive shells. _Alias Expansion_ Aliases are expanded immediately before the command line is parsed as explained in *Note Aliasing::. _Process Substitution_ _Parameter Expansion_ _Command Substitution_ _Arithmetic Expansion_ _Brace Expansion_ These five are performed in one step in left-to-right fashion. After these expansions, all unquoted occurrences of the characters `\', `'' and `"' are removed. _Filename Expansion_ If the SH_FILE_EXPANSION option is set, the order of expansion is modified for compatibility with `sh' and `ksh'. In that case _filename expansion_ is performed immediately after _alias expansion_, preceding the set of five expansions mentioned above. _Filename Generation_ This expansion, commonly referred to as `globbing', is always done last. The following sections explain the types of expansion in detail. * Menu: * History Expansion:: * Process Substitution:: * Parameter Expansion:: * Command Substitution:: * Arithmetic Expansion:: * Brace Expansion:: * Filename Expansion:: * Filename Generation::  File: zsh.info, Node: History Expansion, Next: Process Substitution, Up: Expansion History Expansion ================= History expansion allows you to use words from previous command lines in the command line you are typing. This simplifies spelling corrections and the repetition of complicated commands or arguments. Immediately before execution, each command is saved in the history list, the size of which is controlled by the HISTSIZE parameter. The one most recent command is always retained in any case. Each saved command in the history list is called a history _event_ and is assigned a number, beginning with 1 (one) when the shell starts up. The history number that you may see in your prompt (see *Note Prompt Expansion::) is the number that is to be assigned to the _next_ command. * Menu: * Overview:: * Event Designators:: * Word Designators:: * Modifiers::  File: zsh.info, Node: Overview, Next: Event Designators, Up: History Expansion Overview -------- A history expansion begins with the first character of the histchars parameter, which is `!' by default, and may occur anywhere on the command line; history expansions do not nest. The `!' can be escaped with `\' or can be enclosed between a pair of single quotes ('') to suppress its special meaning. Double quotes will _not_ work for this. Following this history character is an optional event designator (*Note Event Designators::) and then an optional word designator (*Note Word Designators::); if neither of these designators is present, no history expansion occurs. Input lines containing history expansions are echoed after being expanded, but before any other expansions take place and before the command is executed. It is this expanded form that is recorded as the history event for later references. By default, a history reference with no event designator refers to the same event as any preceding history reference on that command line; if it is the only history reference in a command, it refers to the previous command. However, if the option CSH_JUNKIE_HISTORY is set, then every history reference with no event specification _always_ refers to the previous command. For example, `!' is the event designator for the previous command, so `!!:1' always refers to the first word of the previous command, and `!!$' always refers to the last word of the previous command. With CSH_JUNKIE_HISTORY set, then `!:1' and `!$' function in the same manner as `!!:1' and `!!$', respectively. Conversely, if CSH_JUNKIE_HISTORY is unset, then `!:1' and `!$' refer to the first and last words, respectively, of the same event referenced by the nearest other history reference preceding them on the current command line, or to the previous command if there is no preceding reference. The character sequence `^FOO^BAR' (where `^' is actually the second character of the histchars parameter) repeats the last command, replacing the string FOO with BAR. More precisely, the sequence `^FOO^BAR^' is synonymous with `!!:s^FOO^BAR^', hence other modifiers (see *Note Modifiers::) may follow the final `^'. If the shell encounters the character sequence `!"' in the input, the history mechanism is temporarily disabled until the current list (see *Note Shell Grammar::) is fully parsed. The `!"' is removed from the input, and any subsequent `!' characters have no special significance. A less convenient but more comprehensible form of command history support is provided by the fc builtin.  File: zsh.info, Node: Event Designators, Next: Word Designators, Prev: Overview, Up: History Expansion Event Designators ----------------- An event designator is a reference to a command-line entry in the history list. In the list below, remember that the initial `!' in each item may be changed to another character by setting the histchars parameter. ! Start a history expansion, except when followed by a blank, newline, `=' or `('. If followed immediately by a word designator (*Note Word Designators::), this forms a history reference with no event designator (*Note Overview::). !! Refer to the previous command. By itself, this expansion repeats the previous command. !N Refer to command-line N. !-N Refer to the current command-line minus N. !STR Refer to the most recent command starting with STR. !?STR[?] Refer to the most recent command containing STR. The trailing `?' is necessary if this reference is to be followed by a modifier or followed by any text that is not to be considered part of STR. !# Refer to the current command line typed in so far. The line is treated as if it were complete up to and including the word before the one with the `!#' reference. !{...} Insulate a history reference from adjacent characters (if necessary).  File: zsh.info, Node: Word Designators, Next: Modifiers, Prev: Event Designators, Up: History Expansion Word Designators ---------------- A word designator indicates which word or words of a given command line are to be included in a history reference. A `:' usually separates the event specification from the word designator. It may be omitted only if the word designator begins with a `^', `$', `*', `-' or `%'. Word designators include: 0 The first input word (command). N The Nth argument. ^ The first argument. That is, 1. $ The last argument. % The word matched by (the most recent) ?STR search. X-Y A range of words; X defaults to 0. * All the arguments, or a null value if there are none. X* Abbreviates `X-$'. X- Like `X*' but omitting word $. Note that a `%' word designator works only when used in one of `!%', `!:%' or `!?STR?:%', and only when used after a !? expansion (possibly in an earlier command). Anything else results in an error, although the error may not be the most obvious one.  File: zsh.info, Node: Modifiers, Prev: Word Designators, Up: History Expansion Modifiers --------- After the optional word designator, you can add a sequence of one or more of the following modifiers, each preceded by a `:'. These modifiers also work on the result of _filename generation_ and _parameter expansion_, except where noted. h Remove a trailing pathname component, leaving the head. This works like `dirname'. r Remove a filename extension of the form `.XXX', leaving the root name. e Remove all but the extension. t Remove all leading pathname components, leaving the tail. This works like `basename'. p Print the new command but do not execute it. Only works with history expansion. q Quote the substituted words, escaping further substitutions. Works with history expansion and parameter expansion, though for parameters it is only useful if the resulting text is to be re-evaluated such as by eval. Q Remove one level of quotes from the substituted words. x Like q, but break into words at whitespace. Does not work with parameter expansion. l Convert the words to all lowercase. u Convert the words to all uppercase. s/L/R[/] Substitute R for L as described below. Unless preceded immediately by a g, with no colon between, the substitution is done only for the first string that matches L. For arrays and for filename generation, this applies to each word of the expanded text. & Repeat the previous s substitution. Like s, may be preceded immediately by a g. In parameter expansion the & must appear inside braces, and in filename generation it must be quoted with a backslash. The s/l/r/ substitution works as follows. The left-hand side of substitutions are not regular expressions, but character strings. Any character can be used as the delimiter in place of `/'. A backslash quotes the delimiter character. The character `&', in the right-hand-side R, is replaced by the text from the left-hand-side L. The `&' can be quoted with a backslash. A null L uses the previous string either from the previous L or from the contextual scan string S from `!?S'. You can omit the rightmost delimiter if a newline immediately follows R; the rightmost `?' in a context scan can similarly be omitted. Note the same record of the last L and R is maintained across all forms of expansion. The following f, F, w and W modifiers work only with parameter expansion and filename generation. They are listed here to provide a single point of reference for all modifiers. f Repeats the immediately (without a colon) following modifier until the resulting word doesn't change any more. F:EXPR: Like f, but repeats only N times if the expression EXPR evaluates to N. Any character can be used instead of the `:'; if `(', `[', or `{' is used as the opening delimiter, the closing delimiter should be ')', `]', or `}', respectively. w Makes the immediately following modifier work on each word in the string. W:SEP: Like w but words are considered to be the parts of the string that are separated by SEP. Any character can be used instead of the `:'; opening parentheses are handled specially, see above.  File: zsh.info, Node: Process Substitution, Next: Parameter Expansion, Prev: History Expansion, Up: Expansion Process Substitution ==================== Each command argument of the form `<(LIST)', `>(LIST)' or `=(LIST)' is subject to process substitution. In the case of the < or > forms, the shell runs process LIST asynchronously. If the system supports the /dev/fd mechanism, the command argument is the name of the device file corresponding to a file descriptor; otherwise, if the system supports named pipes (FIFOs), the command argument will be a named pipe. If the form with > is selected then writing on this special file will provide input for LIST. If < is used, then the file passed as an argument will be connected to the output of the LIST process. For example, paste <(cut -f1 FILE1) <(cut -f3 FILE2) | tee >(PROCESS1) >(PROCESS2) >/dev/null cuts fields 1 and 3 from the files FILE1 and FILE2 respectively, pastes the results together, and sends it to the processes PROCESS1 and PROCESS2. If =(...) is used instead of <(...), then the file passed as an argument will be the name of a temporary file containing the output of the LIST process. This may be used instead of the < form for a program that expects to lseek (see man page lseek(2)) on the input file. The = form is useful as both the /dev/fd and the named pipe implementation of <(...) have drawbacks. In the former case, some programmes may automatically close the file descriptor in question before examining the file on the command line, particularly if this is necessary for security reasons such as when the programme is running setuid. In the second case, if the programme does not actually open the file, the subshell attempting to read from or write to the pipe will (in a typical implementation, different operating systems may have different behaviour) block for ever and have to be killed explicitly. In both cases, the shell actually supplies the information using a pipe, so that programmes that expect to lseek (see man page lseek(2)) on the file will not work. Also note that the previous example can be more compactly and efficiently written (provided the MULTIOS option is set) as: paste <(cut -f1 FILE1) <(cut -f3 FILE2) > >(PROCESS1) > >(PROCESS2) The shell uses pipes instead of FIFOs to implement the latter two process substitutions in the above example. There is an additional problem with >(PROCESS); when this is attached to an external command, the parent shell does not wait for PROCESS to finish and hence an immediately following command cannot rely on the results being complete. The problem and solution are the same as described in the section _MULTIOS_ in *Note Redirection::. Hence in a simplified version of the example above: paste <(cut -f1 FILE1) <(cut -f3 FILE2) > >(PROCESS) (note that no MULTIOS are involved), PROCESS will be run asynchronously. The workaround is: { paste <(cut -f1 FILE1) <(cut -f3 FILE2) } > >(PROCESS) The extra processes here are spawned from the parent shell which will wait for their completion.  File: zsh.info, Node: Parameter Expansion, Next: Command Substitution, Prev: Process Substitution, Up: Expansion Parameter Expansion =================== The character `$' is used to introduce parameter expansions. See *Note Parameters:: for a description of parameters, including arrays, associative arrays, and subscript notation to access individual array elements. Note in particular the fact that words of unquoted parameters are not automatically split on whitespace unless the option SH_WORD_SPLIT is set; see references to this option below for more details. This is an important difference from other shells. In the expansions discussed below that require a pattern, the form of the pattern is the same as that used for filename generation; see *Note Filename Generation::. Note that these patterns, along with the replacement text of any substitutions, are themselves subject to parameter expansion, command substitution, and arithmetic expansion. In addition to the following operations, the colon modifiers described in *Note Modifiers:: in *Note History Expansion:: can be applied: for example, ${i:s/foo/bar/} performs string substitution on the expansion of parameter $i. ${NAME} The value, if any, of the parameter NAME is substituted. The braces are required if the expansion is to be followed by a letter, digit, or underscore that is not to be interpreted as part of NAME. In addition, more complicated forms of substitution usually require the braces to be present; exceptions, which only apply if the option KSH_ARRAYS is not set, are a single subscript or any colon modifiers appearing after the name, or any of the characters `^', `=', `~', `#' or `+' appearing before the name, all of which work with or without braces. If NAME is an array parameter, and the KSH_ARRAYS option is not set, then the value of each element of NAME is substituted, one element per word. Otherwise, the expansion results in one word only; with KSH_ARRAYS, this is the first element of an array. No field splitting is done on the result unless the SH_WORD_SPLIT option is set. ${+NAME} If NAME is the name of a set parameter `1' is substituted, otherwise `0' is substituted. ${NAME:-WORD} If NAME is set and is non-null then substitute its value; otherwise substitute WORD. If NAME is missing, substitute WORD. ${NAME:=WORD} ${NAME::=WORD} In the first form, if NAME is unset or is null then set it to WORD; in the second form, unconditionally set NAME to WORD. In both forms, the value of the parameter is then substituted. ${NAME:?WORD} If NAME is set and is non-null then substitute its value; otherwise, print WORD and exit from the shell. Interactive shells instead return to the prompt. If WORD is omitted, then a standard message is printed. ${NAME:+WORD} If NAME is set and is non-null then substitute WORD; otherwise substitute nothing. If the colon is omitted from one of the above expressions containing a colon, then the shell only checks whether NAME is set, not whether its value is null. In the following expressions, when NAME is an array and the substitution is not quoted, or if the `(@)' flag or the NAME[@] syntax is used, matching and replacement is performed on each array element separately. ${NAME#PATTERN} ${NAME##PATTERN} If the PATTERN matches the beginning of the value of NAME, then substitute the value of NAME with the matched portion deleted; otherwise, just substitute the value of NAME. In the first form, the smallest matching pattern is preferred; in the second form, the largest matching pattern is preferred. ${NAME%PATTERN} ${NAME%%PATTERN} If the PATTERN matches the end of the value of NAME, then substitute the value of NAME with the matched portion deleted; otherwise, just substitute the value of NAME. In the first form, the smallest matching pattern is preferred; in the second form, the largest matching pattern is preferred. ${NAME:#PATTERN} If the PATTERN matches the value of NAME, then substitute the empty string; otherwise, just substitute the value of NAME. If NAME is an array the matching array elements are removed (use the `(M)' flag to remove the non-matched elements). ${NAME/PATTERN/REPL} ${NAME//PATTERN/REPL} Replace the longest possible match of PATTERN in the expansion of parameter NAME by string REPL. The first form replaces just the first occurrence, the second form all occurrences. Both PATTERN and REPL are subject to double-quoted substitution, so that expressions like ${name/$opat/$npat} will work, but note the usual rule that pattern characters in $opat are not treated specially unless either the option GLOB_SUBST is set, or $opat is instead substituted as ${~opat}. The PATTERN may begin with a `#', in which case the PATTERN must match at the start of the string, or `%', in which case it must match at the end of the string. The REPL may be an empty string, in which case the final `/' may also be omitted. To quote the final `/' in other cases it should be preceded by a single backslash; this is not necessary if the `/' occurs inside a substituted parameter. Note also that the `#' and `%' are not active if they occur inside a substituted parameter, even at the start. The first `/' may be preceded by a `:', in which case the match will only succeed if it matches the entire word. Note also the effect of the I and S parameter expansion flags below; however, the flags M, R, B, E and N are not useful. For example, foo="twinkle twinkle little star" sub="t*e" rep="spy" print ${foo//${~sub}/$rep} print ${(S)foo//${~sub}/$rep} Here, the `~' ensures that the text of $sub is treated as a pattern rather than a plain string. In the first case, the longest match for t*e is substituted and the result is `spy star', while in the second case, the shortest matches are taken and the result is `spy spy lispy star'. ${#SPEC} If SPEC is one of the above substitutions, substitute the length in characters of the result instead of the result itself. If SPEC is an array expression, substitute the number of elements of the result. Note that `^', `=', and `~', below, must appear to the left of `#' when these forms are combined. ${^SPEC} Turn on the RC_EXPAND_PARAM option for the evaluation of SPEC; if the `^' is doubled, turn it off. When this option is set, array expansions of the form FOO${XX}BAR, where the parameter XX is set to (A B C), are substituted with `FOOABAR FOOBBAR FOOCBAR' instead of the default `FOOA B CBAR'. Internally, each such expansion is converted into the equivalent list for brace expansion. E.g., ${^var} becomes {$var[1],$var[2],...}, and is processed as described in *Note Brace Expansion:: below. If word splitting is also in effect the $var[N] may themselves be split into different list elements. ${=SPEC} Perform word splitting using the rules for SH_WORD_SPLIT during the evaluation of SPEC, but regardless of whether the parameter appears in double quotes; if the `=' is doubled, turn it off. This forces parameter expansions to be split into separate words before substitution, using IFS as a delimiter. This is done by default in most other shells. Note that splitting is applied to WORD in the assignment forms of SPEC _before_ the assignment to NAME is performed. This affects the result of array assignments with the A flag. ${~SPEC} Turn on the GLOB_SUBST option for the evaluation of SPEC; if the `~' is doubled, turn it off. When this option is set, the string resulting from the expansion will be interpreted as a pattern anywhere that is possible, such as in filename expansion and filename generation and pattern-matching contexts like the right hand side of the `=' and `!=' operators in conditions. If a ${...} type parameter expression or a $(...) type command substitution is used in place of NAME above, it is expanded first and the result is used as if it were the value of NAME. Thus it is possible to perform nested operations: ${${foo#head}%tail} substitutes the value of $foo with both `head' and `tail' deleted. The form with $(...) is often useful in combination with the flags described next; see the examples below. Each NAME or nested ${...} in a parameter expansion may also be followed by a subscript expression as described in *Note Array Parameters::. Note that double quotes may appear around nested expressions, in which case only the part inside is treated as quoted; for example, ${(f)"$(foo)"} quotes the result of $(foo), but the flag `(f)' (see below) is applied using the rules for unquoted expansions. Note further that quotes are themselves nested in this context; for example, in "${(@f)"$(foo)"}", there are two sets of quotes, one surrounding the whole expression, the other (redundant) surrounding the $(foo) as before. Parameter Expansion Flags ------------------------- If the opening brace is directly followed by an opening parenthesis, the string up to the matching closing parenthesis will be taken as a list of flags. In cases where repeating a flag is meaningful, the repetitions need not be consecutive; for example, `(q%q%q)' means the same thing as the more readable `(%%qqq)'. The following flags are supported: % Expand all % escapes in the resulting words in the same way as in in prompts (see *Note Prompt Expansion::). If this flag is given twice, full prompt expansion is done on the resulting words, depending on the setting of the PROMPT_PERCENT, PROMPT_SUBST and PROMPT_BANG options. @ In double quotes, array elements are put into separate words. E.g., `"${(@)foo}"' is equivalent to `"${foo[@]}"' and `"${(@)foo[1,2]}"' is the same as `"$foo[1]" "$foo[2]"'. This is distinct from _field splitting_ by the the f, s or z flags, which still applies within each array element. A Create an array parameter with `${...=...}', `${...:=...}' or `${...::=...}'. If this flag is repeated (as in `AA'), create an associative array parameter. Assignment is made before sorting or padding. The NAME part may be a subscripted range for ordinary arrays; the WORD part _must_ be converted to an array, for example by using `${(AA)=NAME=...}' to activate field splitting, when creating an associative array. a With o or O, sort in array index order. Note that `oa' is therefore equivalent to the default but `Oa' is useful for obtaining an array's elements in reverse order. c With ${#NAME}, count the total number of characters in an array, as if the elements were concatenated with spaces between them. C Capitalize the resulting words. `Words' in this case refers to sequences of alphanumeric characters separated by non-alphanumerics, _not_ to words that result from field splitting. e Perform _parameter expansion_, _command substitution_ and _arithmetic expansion_ on the result. Such expansions can be nested but too deep recursion may have unpredictable effects. f Split the result of the expansion to lines. This is a shorthand for `ps:\n:'. F Join the words of arrays together using newline as a separator. This is a shorthand for `pj:\n:'. i With o or O, sort case-independently. k If NAME refers to an associative array, substitute the _keys_ (element names) rather than the values of the elements. Used with subscripts (including ordinary arrays), force indices or keys to be substituted even if the subscript form refers to values. However, this flag may not be combined with subscript ranges. L Convert all letters in the result to lower case. n With o or O, sort numerically. o Sort the resulting words in ascending order. O Sort the resulting words in descending order. P This forces the value of the parameter NAME to be interpreted as a further parameter name, whose value will be used where appropriate. If used with a nested parameter or command substitution, the result of that will be taken as a parameter name in the same way. For example, if you have `foo=bar' and `bar=baz', the strings ${(P)foo}, ${(P)${foo}}, and ${(P)$(echo bar)} will be expanded to `baz'. q Quote the resulting words with backslashes. If this flag is given twice, the resulting words are quoted in single quotes and if it is given three times, the words are quoted in double quotes. If it is given four times, the words are quoted in single quotes preceded by a $. Q Remove one level of quotes from the resulting words. t Use a string describing the type of the parameter where the value of the parameter would usually appear. This string consists of keywords separated by hyphens (`-'). The first keyword in the string describes the main type, it can be one of `scalar', `array', `integer', `float' or `association'. The other keywords describe the type in more detail: local for local parameters left for left justified parameters right_blanks for right justified parameters with leading blanks right_zeros for right justified parameters with leading zeros lower for parameters whose value is converted to all lower case when it is expanded upper for parameters whose value is converted to all upper case when it is expanded readonly for readonly parameters tag for tagged parameters export for exported parameters unique for arrays which keep only the first occurrence of duplicated values hide for parameters with the `hide' flag special for special parameters defined by the shell u Expand only the first occurrence of each unique word. U Convert all letters in the result to upper case. v Used with k, substitute (as two consecutive words) both the key and the value of each associative array element. Used with subscripts, force values to be substituted even if the subscript form refers to indices or keys. V Make any special characters in the resulting words visible. w With ${#NAME}, count words in arrays or strings; the s flag may be used to set a word delimiter. W Similar to w with the difference that empty words between repeated delimiters are also counted. X With this flag parsing errors occurring with the Q and e flags or the pattern matching forms such as `${NAME#PATTERN}' are reported. Without the flag they are silently ignored. z Split the result of the expansion into words using shell parsing to find the words, i.e. taking into account any quoting in the value. Note that this is done very late, as for the `(s)' flag. So to access single words in the result, one has to use nested expansions as in `${${(z)foo}[2]}'. Likewise, to remove the quotes in the resulting words one would do: `${(Q)${(z)foo}}'. The following flags (except p) are followed by one or more arguments as shown. Any character, or the matching pairs `(...)', `{...}', `[...]', or `<...>', may be used in place of a colon as delimiters, but note that when a flag takes more than one argument, a matched pair of delimiters must surround each argument. p Recognize the same escape sequences as the print builtin in string arguments to any of the flags described below. j:STRING: Join the words of arrays together using STRING as a separator. Note that this occurs before field splitting by the SH_WORD_SPLIT option. l:EXPR::STRING1::STRING2: Pad the resulting words on the left. Each word will be truncated if required and placed in a field EXPR characters wide. The space to the left will be filled with STRING1 (concatenated as often as needed) or spaces if STRING1 is not given. If both STRING1 and STRING2 are given, this string is inserted once directly to the left of each word, before padding. r:EXPR::STRING1::STRING2: As l, but pad the words on the right and insert STRING2 on the right. s:STRING: Force field splitting (see the option SH_WORD_SPLIT) at the separator STRING. Note that a STRING of two or more characters means all must all match in sequence; this differs from the treatment of two or more characters in the IFS parameter. The following flags are meaningful with the ${...#...} or ${...%...} forms. The S and I flags may also be used with the ${.../...} forms. S Search substrings as well as beginnings or ends; with # start from the beginning and with % start from the end of the string. With substitution via ${.../...} or ${...//...}, specifies non-greedy matching, i.e. that the shortest instead of the longest match should be replaced. I:EXPR: Search the EXPRth match (where EXPR evaluates to a number). This only applies when searching for substrings, either with the S flag, or with ${.../...} (only the EXPRth match is substituted) or ${...//...} (all matches from the EXPRth on are substituted). The default is to take the first match. The EXPRth match is counted such that there is either one or zero matches from each starting position in the string, although for global substitution matches overlapping previous replacements are ignored. With the ${...%...} and ${...%%...} forms, the starting position for the match moves backwards from the end as the index increases, while with the other forms it moves forward from the start. Hence with the string which switch is the right switch for Ipswich? substitutions of the form ${(SI:N:)string#w*ch} as N increases from 1 will match and remove `which', `witch', `witch' and `wich'; the form using `##' will match and remove `which switch is the right switch for Ipswich', `witch is the right switch for Ipswich', `witch for Ipswich' and `wich'. The form using `%' will remove the same matches as for `#', but in reverse order, and the form using `%%' will remove the same matches as for `##' in reverse order. B Include the index of the beginning of the match in the result. E Include the index of the end of the match in the result. M Include the matched portion in the result. N Include the length of the match in the result. R Include the unmatched portion in the result (the _R_est). Rules ----- Here is a summary of the rules for substitution; this assumes that braces are present around the substitution, i.e. ${...}. Some particular examples are given below. Note that the Zsh Development Group accepts _no responsibility_ for any brain damage which may occur during the reading of the following rules. 1. _Nested Substitution_ If multiple nested ${...} forms are present, substitution is performed from the inside outwards. At each level, the substitution takes account of whether the current value is a scalar or an array, whether the whole substitution is in double quotes, and what flags are supplied to the current level of substitution, just as if the nested substitution were the outermost. The flags are not propagated up to enclosing substitutions; the nested substitution will return either a scalar or an array as determined by the flags, possibly adjusted for quoting. All the following steps take place where applicable at all levels of substitution. Note that, unless the `(P)' flag is present, the flags and any subscripts apply directly to the value of the nested substitution; for example, the expansion ${${foo}} behaves exactly the same as ${foo}. 2. _Parameter Subscripting_ If the value is a raw parameter reference with a subscript, such as ${VAR[3]}, the effect of subscripting is applied directly to the parameter. Subscripts are evaluated left to right; subsequent subscripts apply to the scalar or array value yielded by the previous subscript. Thus if var is an array, ${var[1][2]} is the second character of the first word, but ${var[2,4][2]} is the entire third word (the second word of the range of words two through four of the original array). Any number of subscripts may appear. 3. _Parameter Name Replacement_ The effect of any (P) flag, which treats the value so far as a parameter name and replaces it with the corresponding value, is applied. 4. _Double-Quoted Joining_ If the value after this process is an array, and the substitution appears in double quotes, and no (@) flag is present at the current level, the words of the value are joined with the first character of the parameter $IFS, by default a space, between each word (single word arrays are not modified). If the (j) flag is present, that is used for joining instead of $IFS. 5. _Nested Subscripting_ Any remaining subscripts (i.e. of a nested substitution) are evaluated at this point, based on whether the value is an array or a scalar. As with 2., multiple subscripts can appear. Note that ${foo[2,4][2]} is thus equivalent to ${${foo[2,4]}[2]} and also to "${${(@)foo[2,4]}[2]}" (the nested substitution returns an array in both cases), but not to "${${foo[2,4]}[2]}" (the nested substitution returns a scalar because of the quotes). 6. _Modifiers_ Any modifiers, as specified by a trailing `#', `%', `/' (possibly doubled) or by a set of modifiers of the form :... (see *Note Modifiers:: in *Note History Expansion::), are applied to the words of the value at this level. 7. _Forced Joining_ If the `(j)' flag is present, or no `(j)' flag is present but the string is to be split as given by rules 8. or 9., and joining did not take place at step 4., any words in the value are joined together using the given string or the first character of $IFS if none. Note that the `(F)' flag implicitly supplies a string for joining in this manner. 8. _Forced Splitting_ If one of the `(s)', `(f)' or `(z)' flags are present, or the `=' specifier was present (e.g. ${=VAR}), the word is split on occurrences of the specified string, or (for = with neither of the two flags present) any of the characters in $IFS. 9. _Shell Word Splitting_ If no `(s)', `(f)' or `=' was given, but the word is not quoted and the option SH_WORD_SPLIT is set, the word is split on occurrences of any of the characters in $IFS. Note this step, too, takes place at all levels of a nested substitution. 10. _Re-Evaluation_ Any `(e)' flag is applied to the value, forcing it to be re-examined for new parameter substitutions, but also for command and arithmetic substitutions. 11. _Padding_ Any padding of the value by the `(l.FILL.)' or `(r.FILL.)' flags is applied. 12. _Semantic Joining_ In contexts where expansion semantics requires a single word to result, all words are rejoined with the first character of IFS between. So in `${(P)${(f)lines}}' the value of ${lines} is split at newlines, but then must be joined again before the P flag can be applied. If a single word is not required, this rule is skipped. Examples -------- The flag f is useful to split a double-quoted substitution line by line. For example, ${(f)"$( Matches any number in the range X to Y, inclusive. Either of the numbers may be omitted to make the range open-ended; hence `<->' matches any number. To match individual digits, the [...] form is more efficient. Be careful when using other wildcards adjacent to patterns of this form; for example, <0-9>* will actually match any number whatsoever at the start of the string, since the `<0-9>' will match the first digit, and the `*' will match any others. This is a trap for the unwary, but is in fact an inevitable consequence of the rule that the longest possible match always succeeds. Expressions such as `<0-9>[^[:digit:]]*' can be used instead. (...) Matches the enclosed pattern. This is used for grouping. If the KSH_GLOB option is set, then a `@', `*', `+', `?' or `!' immediately preceding the `(' is treated specially, as detailed below. The option SH_GLOB prevents bare parentheses from being used in this way, though the KSH_GLOB option is still available. Note that grouping cannot extend over multiple directories: it is an error to have a `/' within a group (this only applies for patterns used in filename generation). There is one exception: a group of the form (PAT/)# appearing as a complete path segment can match a sequence of directories. For example, foo/(a*/)#bar matches foo/bar, foo/any/bar, foo/any/anyother/bar, and so on. X|Y Matches either X or Y. This operator has lower precedence than any other. The `|' character must be within parentheses, to avoid interpretation as a pipeline. ^X (Requires EXTENDED_GLOB to be set.) Matches anything except the pattern X. This has a higher precedence than `/', so `^foo/bar' will search directories in `.' except `./foo' for a file named `bar'. X~Y (Requires EXTENDED_GLOB to be set.) Match anything that matches the pattern X but does not match Y. This has lower precedence than any operator except `|', so `*/*~foo/bar' will search for all files in all directories in `.' and then exclude `foo/bar' if there was such a match. Multiple patterns can be excluded by `FOO~BAR~BAZ'. In the exclusion pattern (Y), `/' and `.' are not treated specially the way they usually are in globbing. X# (Requires EXTENDED_GLOB to be set.) Matches zero or more occurrences of the pattern X. This operator has high precedence; `12#' is equivalent to `1(2#)', rather than `(12)#'. It is an error for an unquoted `#' to follow something which cannot be repeated; this includes an empty string, a pattern already followed by `##', or parentheses when part of a KSH_GLOB pattern (for example, `!(FOO)#' is invalid and must be replaced by `*(!(FOO))'). X## (Requires EXTENDED_GLOB to be set.) Matches one or more occurrences of the pattern X. This operator has high precedence; `12##' is equivalent to `1(2##)', rather than `(12)##'. No more than two active `#' characters may appear together. ksh-like Glob Operators ----------------------- If the KSH_GLOB option is set, the effects of parentheses can be modified by a preceding `@', `*', `+', `?' or `!'. This character need not be unquoted to have special effects, but the `(' must be. @(...) Match the pattern in the parentheses. (Like `(...)'.) *(...) Match any number of occurrences. (Like `(...)#'.) +(...) Match at least one occurrence. (Like `(...)##'.) ?(...) Match zero or one occurrence. (Like `(|...)'.) !(...) Match anything but the expression in parentheses. (Like `(^(...))'.) Precedence ---------- The precedence of the operators given above is (highest) `^', `/', `~', `|' (lowest); the remaining operators are simply treated from left to right as part of a string, with `#' and `##' applying to the shortest possible preceding unit (i.e. a character, `?', `[...]', `<...>', or a parenthesised expression). As mentioned above, a `/' used as a directory separator may not appear inside parentheses, while a `|' must do so; in patterns used in other contexts than filename generation (for example, in case statements and tests within `[[...]]'), a `/' is not special; and `/' is also not special after a `~' appearing outside parentheses in a filename pattern. Globbing Flags -------------- There are various flags which affect any text to their right up to the end of the enclosing group or to the end of the pattern; they require the EXTENDED_GLOB option. All take the form (#X) where X may have one of the following forms: i Case insensitive: upper or lower case characters in the pattern match upper or lower case characters. l Lower case characters in the pattern match upper or lower case characters; upper case characters in the pattern still only match upper case characters. I Case sensitive: locally negates the effect of i or l from that point on. b Activate backreferences for parenthesised groups in the pattern; this does not work in filename generation. When a pattern with a set of active parentheses is matched, the strings matched by the groups are stored in the array $match, the indices of the beginning of the matched parentheses in the array $mbegin, and the indices of the end in the array $mend, with the first element of each array corresponding to the first parenthesised group, and so on. These arrays are not otherwise special to the shell. The indices use the same convention as does parameter substitution, so that elements of $mend and $mbegin may be used in subscripts; the KSH_ARRAYS option is respected. Sets of globbing flags are not considered parenthesised groups; only the first nine active parentheses can be referenced. For example, foo="a string with a message" if [[ $foo = (a|an)' '(#b)(*)' '* ]]; then print ${foo[$mbegin[1],$mend[1]]} fi prints `string with a'. Note that the first parenthesis is before the (#b) and does not create a backreference. Backreferences work with all forms of pattern matching other than filename generation, but note that when performing matches on an entire array, such as ${ARRAY#PATTERN}, or a global substitution, such as ${PARAM//PAT/REPL}, only the data for the last match remains available. In the case of global replacements this may still be useful. See the example for the m flag below. The numbering of backreferences strictly follows the order of the opening parentheses from left to right in the pattern string, although sets of parentheses may be nested. There are special rules for parentheses followed by `#' or `##'. Only the last match of the parenthesis is remembered: for example, in `[[ abab = (#b)([ab])# ]]', only the final `b' is stored in match[1]. Thus extra parentheses may be necessary to match the complete segment: for example, use `X((ab|cd)#)Y' to match a whole string of either `ab' or `cd' between `X' and `Y', using the value of $match[1] rather than $match[2]. If the match fails none of the parameters is altered, so in some cases it may be necessary to initialise them beforehand. If some of the backreferences fail to match -- which happens if they are in an alternate branch which fails to match, or if they are followed by # and matched zero times -- then the matched string is set to the empty string, and the start and end indices are set to -1. Pattern matching with backreferences is slightly slower than without. B Deactivate backreferences, negating the effect of the b flag from that point on. m Set references to the match data for the entire string matched; this is similar to backreferencing and does not work in filename generation. The flag must be in effect at the end of the pattern, i.e. not local to a group. The parameters $MATCH, $MBEGIN and $MEND will be set to the string matched and to the indices of the beginning and end of the string, respectively. This is most useful in parameter substitutions, as otherwise the string matched is obvious. For example, arr=(veldt jynx grimps waqf zho buck) print ${arr//(#m)[aeiou]/${(U)MATCH}} forces all the matches (i.e. all vowels) into uppercase, printing `vEldt jynx grImps wAqf zhO bUck'. Unlike backreferences, there is no speed penalty for using match references, other than the extra substitutions required for the replacement strings in cases such as the example shown. M Deactivate the m flag, hence no references to match data will be created. aNUM Approximate matching: NUM errors are allowed in the string matched by the pattern. The rules for this are described in the next subsection. s, e Unlike the other flags, these have only a local effect, and each must appear on its own: `(#s)' and `(#e)' are the only valid forms. The `(#s)' flag succeeds only at the start of the test string, and the `(#e)' flag succeeds only at the end of the test string; they correspond to `^' and `$' in standard regular expressions. They are useful for matching path segments in patterns other than those in filename generation (where path segments are in any case treated separately). For example, `*((#s)|/)test((#e)|/)*' matches a path segment `test' in any of the following strings: test, test/at/start, at/end/test, in/test/middle. Another use is in parameter substitution; for example `${array/(#s)A*Z(#e)}' will remove only elements of an array which match the complete pattern `A*Z'. There are other ways of performing many operations of this type, however the combination of the substitution operations `/' and `//' with the `(#s)' and `(#e)' flags provides a single simple and memorable method. Note that assertions of the form `(^(#s))' also work, i.e. match anywhere except at the start of the string, although this actually means `anything except a zero-length portion at the start of the string'; you need to use `(""~(#s))' to match a zero-length portion of the string not at the start. q A `q' and everything up to the closing parenthesis of the globbing flags are ignored by the pattern matching code. This is intended to support the use of glob qualifiers, see below. The result is that the pattern `(#b)(*).c(#q.)' can be used both for globbing and for matching against a string. In the former case, the `(#q.)' will be treated as a glob qualifier and the `(#b)' will not be useful, while in the latter case the `(#b)' is useful for backreferences and the `(#q.)' will be ignored. Note that colon modifiers in the glob qualifiers are also not applied in ordinary pattern matching. For example, the test string fooxx can be matched by the pattern (#i)FOOXX, but not by (#l)FOOXX, (#i)FOO(#I)XX or ((#i)FOOX)X. The string (#ia2)readme specifies case-insensitive matching of readme with up to two errors. When using the ksh syntax for grouping both KSH_GLOB and EXTENDED_GLOB must be set and the left parenthesis should be preceded by @. Note also that the flags do not affect letters inside [...] groups, in other words (#i)[a-z] still matches only lowercase letters. Finally, note that when examining whole paths case-insensitively every directory must be searched for all files which match, so that a pattern of the form (#i)/foo/bar/... is potentially slow. Approximate Matching -------------------- When matching approximately, the shell keeps a count of the errors found, which cannot exceed the number specified in the (#aNUM) flags. Four types of error are recognised: 1. Different characters, as in fooxbar and fooybar. 2. Transposition of characters, as in banana and abnana. 3. A character missing in the target string, as with the pattern road and target string rod. 4. An extra character appearing in the target string, as with stove and strove. Thus, the pattern (#a3)abcd matches dcba, with the errors occurring by using the first rule twice and the second once, grouping the string as [d][cb][a] and [a][bc][d]. Non-literal parts of the pattern must match exactly, including characters in character ranges: hence (#a1)??? matches strings of length four, by applying rule 4 to an empty part of the pattern, but not strings of length two, since all the ? must match. Other characters which must match exactly are initial dots in filenames (unless the GLOB_DOTS option is set), and all slashes in filenames, so that a/bc is two errors from ab/c (the slash cannot be transposed with another character). Similarly, errors are counted separately for non-contiguous strings in the pattern, so that (ab|cd)ef is two errors from aebf. When using exclusion via the ~ operator, approximate matching is treated entirely separately for the excluded part and must be activated separately. Thus, (#a1)README~READ_ME matches READ.ME but not READ_ME, as the trailing READ_ME is matched without approximation. However, (#a1)README~(#a1)READ_ME does not match any pattern of the form READ?ME as all such forms are now excluded. Apart from exclusions, there is only one overall error count; however, the maximum errors allowed may be altered locally, and this can be delimited by grouping. For example, (#a1)cat((#a0)dog)fox allows one error in total, which may not occur in the dog section, and the pattern (#a1)cat(#a0)dog(#a1)fox is equivalent. Note that the point at which an error is first found is the crucial one for establishing whether to use approximation; for example, (#a1)abc(#a0)xyz will not match abcdxyz, because the error occurs at the `x', where approximation is turned off. Entire path segments may be matched approximately, so that `(#a1)/foo/d/is/available/at/the/bar' allows one error in any path segment. This is much less efficient than without the (#a1), however, since every directory in the path must be scanned for a possible approximate match. It is best to place the (#a1) after any path segments which are known to be correct. Recursive Globbing ------------------ A pathname component of the form `(FOO/)#' matches a path consisting of zero or more directories matching the pattern FOO. As a shorthand, `**/' is equivalent to `(*/)#'; note that this therefore matches files in the current directory as well as subdirectories. Thus: ls (*/)#bar or ls **/bar does a recursive directory search for files named `bar' (potentially including the file `bar' in the current directory). This form does not follow symbolic links; the alternative form `***/' does, but is otherwise identical. Neither of these can be combined with other forms of globbing within the same path segment; in that case, the `*' operators revert to their usual effect. Glob Qualifiers --------------- Patterns used for filename generation may end in a list of qualifiers enclosed in parentheses. The qualifiers specify which filenames that otherwise match the given pattern will be inserted in the argument list. If the option BARE_GLOB_QUAL is set, then a trailing set of parentheses containing no `|' or `(' characters (or `~' if it is special) is taken as a set of glob qualifiers. A glob subexpression that would normally be taken as glob qualifiers, for example `(^x)', can be forced to be treated as part of the glob pattern by doubling the parentheses, in this case producing `((^x))'. If the option EXTENDED_GLOB is set, a different syntax for glob qualifiers is available, namely `(#qx)' where x is any of the same glob qualifiers used in the other format. The qualifiers must still appear at the end of the pattern. However, with this syntax multiple glob qualifiers may be chained together. They are treated as a logical AND of the individual sets of flags. Also, as the syntax is unambiguous, the expression will be treated as glob qualifiers just as long any parentheses contained within it are balanced; appearance of `|', `(' or `~' does not negate the effect. Note that qualifiers will be recognised in this form even if a bare glob qualifier exists at the end of the pattern, for example `*(#q*)(.)' will recognise executable regular files if both options are set; however, mixed syntax should probably be avoided for the sake of clarity. A qualifier may be any one of the following: / directories . plain files @ symbolic links = sockets p named pipes (FIFOs) * executable plain files (0100) % device files (character or block special) %b block special files %c character special files r owner-readable files (0400) w owner-writable files (0200) x owner-executable files (0100) A group-readable files (0040) I group-writable files (0020) E group-executable files (0010) R world-readable files (0004) W world-writable files (0002) X world-executable files (0001) s setuid files (04000) S setgid files (02000) t files with the sticky bit (01000) fSPEC files with access rights matching SPEC. This SPEC may be a octal number optionally preceded by a `=', a `+', or a `-'. If none of these characters is given, the behavior is the same as for `='. The octal number describes the mode bits to be expected, if combined with a `=', the value given must match the file-modes exactly, with a `+', at least the bits in the given number must be set in the file-modes, and with a `-', the bits in the number must not be set. Giving a `?' instead of a octal digit anywhere in the number ensures that the corresponding bits in the file-modes are not checked, this is only useful in combination with `='. If the qualifier `f' is followed by any other character anything up to the next matching character (`[', `{', and `<' match `]', `}', and `>' respectively, any other character matches itself) is taken as a list of comma-separated SUB-SPECs. Each SUB-SPEC may be either an octal number as described above or a list of any of the characters `u', `g', `o', and `a', followed by a `=', a `+', or a `-', followed by a list of any of the characters `r', `w', `x', `s', and `t', or an octal digit. The first list of characters specify which access rights are to be checked. If a `u' is given, those for the owner of the file are used, if a `g' is given, those of the group are checked, a `o' means to test those of other users, and the `a' says to test all three groups. The `=', `+', and `-' again says how the modes are to be checked and have the same meaning as described for the first form above. The second list of characters finally says which access rights are to be expected: `r' for read access, `w' for write access, `x' for the right to execute the file (or to search a directory), `s' for the setuid and setgid bits, and `t' for the sticky bit. Thus, `*(f70?)' gives the files for which the owner has read, write, and execute permission, and for which other group members have no rights, independent of the permissions for other users. The pattern `*(f-100)' gives all files for which the owner does not have execute permission, and `*(f:gu+w,o-rx:)' gives the files for which the owner and the other members of the group have at least write permission, and for which other users don't have read or execute permission. eSTRING The STRING will be executed as shell code. The filename will be included in the list if and only if the code returns a zero status (usually the status of the last command). The first character after the `e' will be used as a separator and anything up to the next matching separator will be taken as the STRING; `[', `{', and `<' match `]', `}', and `>', respectively, while any other character matches itself. Note that expansions must be quoted in the STRING to prevent them from being expanded before globbing is done. During the execution of STRING the filename currently being tested is available in the parameter REPLY; the parameter may be altered to a string to be inserted into the list instead of the original filename. In addition, the parameter reply may be set to an array or a string, which overrides the value of REPLY. If set to an array, the latter is inserted into the command line word by word. For example, suppose a directory contains a single file `lonely'. Then the expression `*(e:'reply=(${REPLY}{1,2})':)' will cause the words `lonely1 lonely2' to be inserted into the command line. Note the quotation marks. dDEV files on the device DEV l[-|+]CT files having a link count less than CT (-), greater than CT (+), or equal to CT U files owned by the effective user ID G files owned by the effective group ID uID files owned by user ID ID if it is a number, if not, than the character after the `u' will be used as a separator and the string between it and the next matching separator (`[', `{', and `<' match `]', `}', and `>' respectively, any other character matches itself) will be taken as a user name, and the user ID of this user will be taken (e.g. `u:foo:' or `u[foo]' for user `foo') gID like uID but with group IDs or names a[Mwhms][-|+]N files accessed exactly N days ago. Files accessed within the last N days are selected using a negative value for N (-N). Files accessed more than N days ago are selected by a positive N value (+N). Optional unit specifiers `M', `w', `h', `m' or `s' (e.g. `ah5') cause the check to be performed with months (of 30 days), weeks, hours, minutes or seconds instead of days, respectively. For instance, `echo *(ah-5)' would echo files accessed within the last five hours. m[Mwhms][-|+]N like the file access qualifier, except that it uses the file modification time. c[Mwhms][-|+]N like the file access qualifier, except that it uses the file inode change time. L[+|-]N files less than N bytes (-), more than N bytes (+), or exactly N bytes in length. If this flag is directly followed by a `k' (`K'), `m' (`M'), or `p' (`P') (e.g. `Lk-50') the check is performed with kilobytes, megabytes, or blocks (of 512 bytes) instead. ^ negates all qualifiers following it - toggles between making the qualifiers work on symbolic links (the default) and the files they point to M sets the MARK_DIRS option for the current pattern T appends a trailing qualifier mark to the filenames, analogous to the LIST_TYPES option, for the current pattern (overrides M) N sets the NULL_GLOB option for the current pattern D sets the GLOB_DOTS option for the current pattern n sets the NUMERIC_GLOB_SORT option for the current pattern oC specifies how the names of the files should be sorted. If C is n they are sorted by name (the default); if it is L they are sorted depending on the size (length) of the files; if l they are sorted by the number of links; if a, m, or c they are sorted by the time of the last access, modification, or inode change respectively; if d, files in subdirectories appear before those in the current directory at each level of the search -- this is best combined with other criteria, for example `odon' to sort on names for files within the same directory. Note that a, m, and c compare the age against the current time, hence the first name in the list is the youngest file. Also note that the modifiers ^ and - are used, so `*(^-oL)' gives a list of all files sorted by file size in descending order, following any symbolic links. OC like `o', but sorts in descending order; i.e. `*(^oc)' is the same as `*(Oc)' and `*(^Oc)' is the same as `*(oc)'; `Od' puts files in the current directory before those in subdirectories at each level of the search. [BEG[,END]] specifies which of the matched filenames should be included in the returned list. The syntax is the same as for array subscripts. BEG and the optional END may be mathematical expressions. As in parameter subscripting they may be negative to make them count from the last match backward. E.g.: `*(-OL[1,3])' gives a list of the names of the three largest files. More than one of these lists can be combined, separated by commas. The whole list matches if at least one of the sublists matches (they are `or'ed, the qualifiers in the sublists are `and'ed). Some qualifiers, however, affect all matches generated, independent of the sublist in which they are given. These are the qualifiers `M', `T', `N', `D', `n', `o', `O' and the subscripts given in brackets (`[...]'). If a `:' appears in a qualifier list, the remainder of the expression in parenthesis is interpreted as a modifier (see *Note Modifiers:: in *Note History Expansion::). Note that each modifier must be introduced by a separate `:'. Note also that the result after modification does not have to be an existing file. The name of any existing file can be followed by a modifier of the form `(:..)' even if no actual filename generation is performed. Thus: ls *(-/) lists all directories and symbolic links that point to directories, and ls *(%W) lists all world-writable device files in the current directory, and ls *(W,X) lists all files in the current directory that are world-writable or world-executable, and echo /tmp/foo*(u0^@:t) outputs the basename of all root-owned files beginning with the string `foo' in /tmp, ignoring symlinks, and ls *.*~(lex|parse).[ch](^D^l1) lists all files having a link count of one whose names contain a dot (but not those starting with a dot, since GLOB_DOTS is explicitly switched off) except for lex.c, lex.h, parse.c and parse.h. print b*.pro(#q:s/pro/shmo/)(#q.:s/builtin/shmiltin/) demonstrates how colon modifiers and other qualifiers may be chained together. The ordinary qualifier `.' is applied first, then the colon modifiers in order from left to right. So if EXTENDED_GLOB is set and the base pattern matches the regular file builtin.pro, the shell will print `shmiltin.shmo'.  File: zsh.info, Node: Parameters, Next: Options, Prev: Expansion, Up: Top Parameters ********** Description =========== A parameter has a name, a value, and a number of attributes. A name may be any sequence of alphanumeric characters and underscores, or the single characters `*', `@', `#', `?', `-', `$', or `!'. The value may be a _scalar_ (a string), an integer, an array (indexed numerically), or an _associative_ array (an unordered set of name-value pairs, indexed by name). To declare the type of a parameter, or to assign a scalar or integer value to a parameter, use the typeset builtin. The value of a scalar or integer parameter may also be assigned by writing: NAME=VALUE If the integer attribute, -i, is set for NAME, the VALUE is subject to arithmetic evaluation. Furthermore, by replacing `=' with `+=', a parameter can be added or appended to. See *Note Array Parameters:: for additional forms of assignment. To refer to the value of a parameter, write `$NAME' or `${NAME}'. See *Note Parameter Expansion:: for complete details. In the parameter lists that follow, the mark `' indicates that the parameter is special. Special parameters cannot have their type changed or their readonly attribute turned off, and if a special parameter is unset, then later recreated, the special properties will be retained. `' indicates that the parameter does not exist when the shell initializes in sh or ksh emulation mode. * Menu: * Array Parameters:: * Positional Parameters:: * Local Parameters:: * Parameters Set By The Shell:: * Parameters Used By The Shell::  File: zsh.info, Node: Array Parameters, Next: Positional Parameters, Up: Parameters Array Parameters ================ To assign an array value, write one of: set -A NAME VALUE ... NAME=(VALUE ...) If no parameter NAME exists, an ordinary array parameter is created. If the parameter NAME exists and is a scalar, it is replaced by a new array. Ordinary array parameters may also be explicitly declared with: typeset -a NAME Associative arrays _must_ be declared before assignment, by using: typeset -A NAME When NAME refers to an associative array, the list in an assignment is interpreted as alternating keys and values: set -A NAME KEY VALUE ... NAME=(KEY VALUE ...) Every KEY must have a VALUE in this case. Note that this assigns to the entire array, deleting any elements that do not appear in the list. To create an empty array (including associative arrays), use one of: set -A NAME NAME=() Array Subscripts ---------------- Individual elements of an array may be selected using a subscript. A subscript of the form `[EXP]' selects the single element EXP, where EXP is an arithmetic expression which will be subject to arithmetic expansion as if it were surrounded by `$((...))'. The elements are numbered beginning with 1, unless the KSH_ARRAYS option is set in which case they are numbered from zero. Subscripts may be used inside braces used to delimit a parameter name, thus `${foo[2]}' is equivalent to `$foo[2]'. If the KSH_ARRAYS option is set, the braced form is the only one that works, as bracketed expressions otherwise are not treated as subscripts. The same subscripting syntax is used for associative arrays, except that no arithmetic expansion is applied to EXP. However, the parsing rules for arithmetic expressions still apply, which affects the way that certain special characters must be protected from interpretation. See _Subscript Parsing_ below for details. A subscript of the form `[*]' or `[@]' evaluates to all elements of an array; there is no difference between the two except when they appear within double quotes. `"$foo[*]"' evaluates to `"$foo[1] $foo[2] ..."', whereas `"$foo[@]"' evaluates to `"$foo[1]" "$foo[2]" ...'. For associative arrays, `[*]' or `[@]' evaluate to all the values, in no particular order. Note that this does not substitute the keys; see the documentation for the `k' flag under *Note Parameter Expansion:: for complete details. When an array parameter is referenced as `$NAME' (with no subscript) it evaluates to `$NAME[*]', unless the KSH_ARRAYS option is set in which case it evaluates to `${NAME[0]}' (for an associative array, this means the value of the key `0', which may not exist even if there are values for other keys). A subscript of the form `[EXP1,EXP2]' selects all elements in the range EXP1 to EXP2, inclusive. (Associative arrays are unordered, and so do not support ranges.) If one of the subscripts evaluates to a negative number, say -N, then the Nth element from the end of the array is used. Thus `$foo[-3]' is the third element from the end of the array foo, and `$foo[1,-1]' is the same as `$foo[*]'. Subscripting may also be performed on non-array values, in which case the subscripts specify a substring to be extracted. For example, if FOO is set to `foobar', then `echo $FOO[2,5]' prints `ooba'. Array Element Assignment ------------------------ A subscript may be used on the left side of an assignment like so: NAME[EXP]=VALUE In this form of assignment the element or range specified by EXP is replaced by the expression on the right side. An array (but not an associative array) may be created by assignment to a range or element. Arrays do not nest, so assigning a parenthesized list of values to an element or range changes the number of elements in the array, shifting the other elements to accommodate the new values. (This is not supported for associative arrays.) This syntax also works as an argument to the typeset command: typeset "NAME[EXP]"=VALUE The VALUE may _not_ be a parenthesized list in this case; only single-element assignments may be made with typeset. Note that quotes are necessary in this case to prevent the brackets from being interpreted as filename generation operators. The noglob precommand modifier could be used instead. To delete an element of an ordinary array, assign `()' to that element. To delete an element of an associative array, use the unset command: unset "NAME[EXP]" Subscript Flags --------------- If the opening bracket, or the comma in a range, in any subscript expression is directly followed by an opening parenthesis, the string up to the matching closing one is considered to be a list of flags, as in `NAME[(FLAGS)EXP]'. The flags currently understood are: w If the parameter subscripted is a scalar than this flag makes subscripting work on words instead of characters. The default word separator is whitespace. s:STRING: This gives the STRING that separates words (for use with the w flag). p Recognize the same escape sequences as the print builtin in the string argument of a subsequent `s' flag. f If the parameter subscripted is a scalar than this flag makes subscripting work on lines instead of characters, i.e. with elements separated by newlines. This is a shorthand for `pws:\n:'. r Reverse subscripting: if this flag is given, the EXP is taken as a pattern and the result is the first matching array element, substring or word (if the parameter is an array, if it is a scalar, or if it is a scalar and the `w' flag is given, respectively). The subscript used is the number of the matching element, so that pairs of subscripts such as `$foo[(r)??,3]' and `$foo[(r)??,(r)f*]' are possible. If the parameter is an associative array, only the value part of each pair is compared to the pattern, and the result is that value. Reverse subscripts may be used for assigning to ordinary array elements, but not for assigning to associative arrays. R Like `r', but gives the last match. For associative arrays, gives all possible matches. i Like `r', but gives the index of the match instead; this may not be combined with a second argument. On the left side of an assignment, behaves like `r'. For associative arrays, the key part of each pair is compared to the pattern, and the first matching key found is the result. I Like `i', but gives the index of the last match, or all possible matching keys in an associative array. k If used in a subscript on an associative array, this flag causes the keys to be interpreted as patterns, and returns the value for the first key found where EXP is matched by the key. This flag does not work on the left side of an assignment to an associative array element. If used on another type of parameter, this behaves like `r'. K On an associative array this is like `k' but returns all values where EXP is matched by the keys. On other types of parameters this has the same effect as `R'. n:EXPR: If combined with `r', `R', `i' or `I', makes them give the Nth or Nth last match (if EXPR evaluates to N). This flag is ignored when the array is associative. b:EXPR: If combined with `r', `R', `i' or `I', makes them begin at the Nth or Nth last element, word, or character (if EXPR evaluates to N). This flag is ignored when the array is associative. e This flag has no effect and for ordinary arrays is retained for backward compatibility only. For associative arrays, this flag can be used to force * or @ to be interpreted as a single key rather than as a reference to all values. This flag may be used on the left side of an assignment. See _Parameter Expansion Flags_ (*Note Parameter Expansion::) for additional ways to manipulate the results of array subscripting. Subscript Parsing ----------------- This discussion applies mainly to associative array key strings and to patterns used for reverse subscripting (the `r', `R', `i', etc. flags), but it may also affect parameter substitutions that appear as part of an arithmetic expression in an ordinary subscript. It is possible to avoid the use of subscripts in assignments to associative array elements by using the syntax: aa+=('key with "*strange*" characters' 'value string') This adds a new key/value pair if the key is not already present, and replaces the value for the existing key if it is. The basic rule to remember when writing a subscript expression is that all text between the opening `[' and the closing `]' is interpreted _as if_ it were in double quotes (*Note Quoting::). However, unlike double quotes which normally cannot nest, subscript expressions may appear inside double-quoted strings or inside other subscript expressions (or both!), so the rules have two important differences. The first difference is that brackets (`[' and `]') must appear as balanced pairs in a subscript expression unless they are preceded by a backslash (`\'). Therefore, within a subscript expression (and unlike true double-quoting) the sequence `\[' becomes `[', and similarly `\]' becomes `]'. This applies even in cases where a backslash is not normally required; for example, the pattern `[^[]' (to match any character other than an open bracket) should be written `[^\[]' in a reverse-subscript pattern. However, note that `\[^\[\]' and even `\[^[]' mean the _same_ thing, because backslashes are always stripped when they appear before brackets! The same rule applies to parentheses (`(' and `)') and braces (`{' and `}'): they must appear either in balanced pairs or preceded by a backslash, and backslashes that protect parentheses or braces are removed during parsing. This is because parameter expansions may be surrounded balanced braces, and subscript flags are introduced by balanced parenthesis. The second difference is that a double-quote (`"') may appear as part of a subscript expression without being preceded by a backslash, and therefore that the two characters `\"' remain as two characters in the subscript (in true double-quoting, `\"' becomes `"'). However, because of the standard shell quoting rules, any double-quotes that appear must occur in balanced pairs unless preceded by a backslash. This makes it more difficult to write a subscript expression that contains an odd number of double-quote characters, but the reason for this difference is so that when a subscript expression appears inside true double-quotes, one can still write `\"' (rather than `\\\"') for `"'. To use an odd number of double quotes as a key in an assignment, use the typeset builtin and an enclosing pair of double quotes; to refer to the value of that key, again use double quotes: typeset -A aa typeset "aa[one\"two\"three\"quotes]"=QQQ print "$aa[one\"two\"three\"quotes]" It is important to note that the quoting rules do not change when a parameter expansion with a subscript is nested inside another subscript expression. That is, it is not necessary to use additional backslashes within the inner subscript expression; they are removed only once, from the innermost subscript outwards. Parameters are also expanded from the innermost subscript first, as each expansion is encountered left to right in the outer expression. A further complication arises from a way in which subscript parsing is _not_ different from double quote parsing. As in true double-quoting, the sequences `\*', and `\@' remain as two characters when they appear in a subscript expression. To use a literal `*' or `@' as an associative array key, the `e' flag must be used: typeset -A aa aa[(e)*]=star print $aa[(e)*] A last detail must be considered when reverse subscripting is performed. Parameters appearing in the subscript expression are first expanded and then the complete expression is interpreted as a pattern. This has two effects: first, parameters behave as if GLOB_SUBST were on (and it cannot be turned off); second, backslashes are interpreted twice, once when parsing the array subscript and again when parsing the pattern. In a reverse subscript, it's necessary to use _four_ backslashes to cause a single backslash to match literally in the pattern. For complex patterns, it is often easiest to assign the desired pattern to a parameter and then refer to that parameter in the subscript, because then the backslashes, brackets, parentheses, etc., are seen only when the complete expression is converted to a pattern. To match the value of a parameter literally in a reverse subscript, rather than as a pattern, use `${(q)NAME}' (*Note Parameter Expansion::) to quote the expanded value. Note that the `k' and `K' flags are reverse subscripting for an ordinary array, but are _not_ reverse subscripting for an associative array! (For an associative array, the keys in the array itself are interpreted as patterns by those flags; the subscript is a plain string in that case.) One final note, not directly related to subscripting: the numeric names of positional parameters (*Note Positional Parameters::) are parsed specially, so for example `$2foo' is equivalent to `${2}foo'. Therefore, to use subscript syntax to extract a substring from a positional parameter, the expansion must be surrounded by braces; for example, `${2[3,5]}' evaluates to the third through fifth characters of the second positional parameter, but `$2[3,5]' is the entire second parameter concatenated with the filename generation pattern `[3,5]'.  File: zsh.info, Node: Positional Parameters, Next: Local Parameters, Prev: Array Parameters, Up: Parameters Positional Parameters ===================== The positional parameters provide access to the command-line arguments of a shell function, shell script, or the shell itself; see *Note Invocation::, and also *Note Functions::. The parameter N, where N is a number, is the Nth positional parameter. The parameters *, @ and argv are arrays containing all the positional parameters; thus `$argv[N]', etc., is equivalent to simply `$N'. Positional parameters may be changed after the shell or function starts by using the set builtin, by assigning to the argv array, or by direct assignment of the form `N=VALUE' where N is the number of the positional parameter to be changed. This also creates (with empty values) any of the positions from 1 to N that do not already have values. Note that, because the positional parameters form an array, an array assignment of the form `N=(VALUE ...)' is allowed, and has the effect of shifting all the values at positions greater than N by as many positions as necessary to accommodate the new values.  File: zsh.info, Node: Local Parameters, Next: Parameters Set By The Shell, Prev: Positional Parameters, Up: Parameters Local Parameters ================ Shell function executions delimit scopes for shell parameters. (Parameters are dynamically scoped.) The typeset builtin, and its alternative forms declare, integer, local and readonly (but not export), can be used to declare a parameter as being local to the innermost scope. When a parameter is read or assigned to, the innermost existing parameter of that name is used. (That is, the local parameter hides any less-local parameter.) However, assigning to a non-existent parameter, or declaring a new parameter with export, causes it to be created in the _outer_most scope. Local parameters disappear when their scope ends. unset can be used to delete a parameter while it is still in scope; any outer parameter of the same name remains hidden. Special parameters may also be made local; they retain their special attributes unless either the existing or the newly-created parameter has the -h (hide) attribute. This may have unexpected effects: there is no default value, so if there is no assignment at the point the variable is made local, it will be set to an empty value (or zero in the case of integers). The following: typeset PATH=/new/directory:$PATH is valid for temporarily allowing the shell or programmes called from it to find the programs in /new/directory inside a function. Note that the restriction in older versions of zsh that local parameters were never exported has been removed.  File: zsh.info, Node: Parameters Set By The Shell, Next: Parameters Used By The Shell, Prev: Local Parameters, Up: Parameters Parameters Set By The Shell =========================== The following parameters are automatically set by the shell: ! The process ID of the last background command invoked. # The number of positional parameters in decimal. Note that some confusion may occur with the syntax $#PARAM which substitutes the length of PARAM. Use ${#} to resolve ambiguities. In particular, the sequence `$#-...' in an arithmetic expression is interpreted as the length of the parameter -, q.v. ARGC Same as #. $ The process ID of this shell. - Flags supplied to the shell on invocation or by the set or setopt commands. * An array containing the positional parameters. argv Same as *. Assigning to argv changes the local positional parameters, but argv is _not_ itself a local parameter. Deleting argv with unset in any function deletes it everywhere, although only the innermost positional parameter array is deleted (so * and @ in other scopes are not affected). @ Same as argv[@], even when argv is not set. ? The exit value returned by the last command. 0 The name used to invoke the current shell. If the FUNCTION_ARGZERO option is set, this is set temporarily within a shell function to the name of the function, and within a sourced script to the name of the script. status Same as ?. pipestatus An array containing the exit values returned by all commands in the last pipeline. _ The last argument of the previous command. Also, this parameter is set in the environment of every command executed to the full pathname of the command. CPUTYPE The machine type (microprocessor class or machine model), as determined at run time. EGID The effective group ID of the shell process. If you have sufficient privileges, you may change the effective group ID of the shell process by assigning to this parameter. Also (assuming sufficient privileges), you may start a single command with a different effective group ID by `(EGID=GID; command)' EUID The effective user ID of the shell process. If you have sufficient privileges, you may change the effective user ID of the shell process by assigning to this parameter. Also (assuming sufficient privileges), you may start a single command with a different effective user ID by `(EUID=UID; command)' ERRNO The value of errno (see man page errno(3)) as set by the most recently failed system call. This value is system dependent and is intended for debugging purposes. It is also useful with the zsh/system module which allows the number to be turned into a name or message. GID The real group ID of the shell process. If you have sufficient privileges, you may change the group ID of the shell process by assigning to this parameter. Also (assuming sufficient privileges), you may start a single command under a different group ID by `(GID=GID; command)' HOST The current hostname. LINENO The line number of the current line within the current script, sourced file, or shell function being executed, whichever was started most recently. Note that in the case of shell functions the line number refers to the function as it appeared in the original definition, not necessarily as displayed by the functions builtin. LOGNAME If the corresponding variable is not set in the environment of the shell, it is initialized to the login name corresponding to the current login session. This parameter is exported by default but this can be disabled using the typeset builtin. MACHTYPE The machine type (microprocessor class or machine model), as determined at compile time. OLDPWD The previous working directory. This is set when the shell initializes and whenever the directory changes. OPTARG The value of the last option argument processed by the getopts command. OPTIND The index of the last option argument processed by the getopts command. OSTYPE The operating system, as determined at compile time. PPID The process ID of the parent of the shell. PWD The present working directory. This is set when the shell initializes and whenever the directory changes. RANDOM A pseudo-random integer from 0 to 32767, newly generated each time this parameter is referenced. The random number generator can be seeded by assigning a numeric value to RANDOM. The values of RANDOM form an intentionally-repeatable pseudo-random sequence; subshells that reference RANDOM will result in identical pseudo-random values unless the value of RANDOM is referenced or seeded in the parent shell in between subshell invocations. SECONDS The number of seconds since shell invocation. If this parameter is assigned a value, then the value returned upon reference will be the value that was assigned plus the number of seconds since the assignment. Unlike other special parameters, the type of the SECONDS parameter can be changed using the typeset command. Only integer and one of the floating point types are allowed. For example, `typeset -F SECONDS' causes the value to be reported as a floating point number. The precision is six decimal places, although not all places may be useful. SHLVL Incremented by one each time a new shell is started. signals An array containing the names of the signals. TTY The name of the tty associated with the shell, if any. TTYIDLE The idle time of the tty associated with the shell in seconds or -1 if there is no such tty. UID The real user ID of the shell process. If you have sufficient privileges, you may change the user ID of the shell by assigning to this parameter. Also (assuming sufficient privileges), you may start a single command under a different user ID by `(UID=UID; command)' USERNAME The username corresponding to the real user ID of the shell process. If you have sufficient privileges, you may change the username (and also the user ID and group ID) of the shell by assigning to this parameter. Also (assuming sufficient privileges), you may start a single command under a different username (and user ID and group ID) by `(USERNAME=USERNAME; command)' VENDOR The vendor, as determined at compile time. ZSH_NAME Expands to the basename of the command used to invoke this instance of zsh. ZSH_VERSION The version number of this zsh.  File: zsh.info, Node: Parameters Used By The Shell, Prev: Parameters Set By The Shell, Up: Parameters Parameters Used By The Shell ============================ The following parameters are used by the shell. In cases where there are two parameters with an upper- and lowercase form of the same name, such as path and PATH, the lowercase form is an array and the uppercase form is a scalar with the elements of the array joined together by colons. These are similar to tied parameters created via `typeset -T'. The normal use for the colon-separated form is for exporting to the environment, while the array form is easier to manipulate within the shell. Note that unsetting either of the pair will unset the other; they retain their special properties when recreated, and recreating one of the pair will recreate the other. ARGV0 If exported, its value is used as the argv[0] of external commands. Usually used in constructs like `ARGV0=emacs nethack'. BAUD The baud rate of the current connection. Used by the line editor update mechanism to compensate for a slow terminal by delaying updates until necessary. This may be profitably set to a lower value in some circumstances, e.g. for slow modems dialing into a communications server which is connected to a host via a fast link; in this case, this variable would be set by default to the speed of the fast link, and not the modem. This parameter should be set to the baud rate of the slowest part of the link for best performance. The compensation mechanism can be turned off by setting the variable to zero. cdpath (CDPATH ) An array (colon-separated list) of directories specifying the search path for the cd command. COLUMNS The number of columns for this terminal session. Used for printing select lists and for the line editor. DIRSTACKSIZE The maximum size of the directory stack. If the stack gets larger than this, it will be truncated automatically. This is useful with the AUTO_PUSHD option. ENV If the ENV environment variable is set when zsh is invoked as sh or ksh, $ENV is sourced after the profile scripts. The value of ENV is subjected to parameter expansion, command substitution, and arithmetic expansion before being interpreted as a pathname. Note that ENV is _not_ used unless zsh is emulating `sh' or `ksh'. FCEDIT The default editor for the fc builtin. fignore (FIGNORE ) An array (colon separated list) containing the suffixes of files to be ignored during filename completion. However, if completion only generates files with suffixes in this list, then these files are completed anyway. fpath (FPATH ) An array (colon separated list) of directories specifying the search path for function definitions. This path is searched when a function with the -u attribute is referenced. If an executable file is found, then it is read and executed in the current environment. histchars Three characters used by the shell's history and lexical analysis mechanism. The first character signals the start of a history expansion (default `!'). The second character signals the start of a quick history substitution (default `^'). The third character is the comment character (default `#'). HISTCHARS Same as histchars. (Deprecated.) HISTFILE The file to save the history in when an interactive shell exits. If unset, the history is not saved. HISTSIZE The maximum number of events stored in the internal history list. If you use the HIST_EXPIRE_DUPS_FIRST option, setting this value larger than the SAVEHIST size will give you the difference as a cushion for saving duplicated history events. HOME The default argument for the cd command. IFS Internal field separators (by default space, tab, newline and NUL), that are used to separate words which result from command or parameter expansion and words read by the read builtin. Any characters from the set space, tab and newline that appear in the IFS are called _IFS white space_. One or more IFS white space characters or one non-IFS white space character together with any adjacent IFS white space character delimit a field. If an IFS white space character appears twice consecutively in the IFS, this character is treated as if it were not an IFS white space character. KEYTIMEOUT The time the shell waits, in hundredths of seconds, for another key to be pressed when reading bound multi-character sequences. LANG This variable determines the locale category for any category not specifically selected via a variable starting with `LC_'. LC_ALL This variable overrides the value of the `LANG' variable and the value of any of the other variables starting with `LC_'. LC_COLLATE This variable determines the locale category for character collation information within ranges in glob brackets and for sorting. LC_CTYPE This variable determines the locale category for character handling functions. LC_MESSAGES This variable determines the language in which messages should be written. Note that zsh does not use message catalogs. LC_NUMERIC This variable affects the decimal point character and thousands separator character for the formatted input/output functions and string conversion functions. Note that zsh ignores this setting when parsing floating point mathematical expressions. LC_TIME This variable determines the locale category for date and time formatting in prompt escape sequences. LINES The number of lines for this terminal session. Used for printing select lists and for the line editor. LISTMAX In the line editor, the number of matches to list without asking first. If the value is negative, the list will be shown if it spans at most as many lines as given by the absolute value. If set to zero, the shell asks only if the top of the listing would scroll off the screen. LOGCHECK The interval in seconds between checks for login/logout activity using the watch parameter. MAIL If this parameter is set and mailpath is not set, the shell looks for mail in the specified file. MAILCHECK The interval in seconds between checks for new mail. mailpath (MAILPATH ) An array (colon-separated list) of filenames to check for new mail. Each filename can be followed by a `?' and a message that will be printed. The message will undergo parameter expansion, command substitution and arithmetic expansion with the variable $_ defined as the name of the file that has changed. The default message is `You have new mail'. If an element is a directory instead of a file the shell will recursively check every file in every subdirectory of the element. manpath (MANPATH ) An array (colon-separated list) whose value is not used by the shell. The manpath array can be useful, however, since setting it also sets MANPATH, and vice versa. module_path (MODULE_PATH ) An array (colon-separated list) of directories that zmodload searches for dynamically loadable modules. This is initialized to a standard pathname, usually `/usr/local/lib/zsh/$ZSH_VERSION'. (The `/usr/local/lib' part varies from installation to installation.) For security reasons, any value set in the environment when the shell is started will be ignored. These parameters only exist if the installation supports dynamic module loading. NULLCMD The command name to assume if a redirection is specified with no command. Defaults to cat. For `sh'/`ksh' behavior, change this to :. For `csh'-like behavior, unset this parameter; the shell will print an error message if null commands are entered. path (PATH ) An array (colon-separated list) of directories to search for commands. When this parameter is set, each directory is scanned and all files found are put in a hash table. POSTEDIT This string is output whenever the line editor exits. It usually contains termcap strings to reset the terminal. PROMPT PROMPT2 PROMPT3 PROMPT4 Same as PS1, PS2, PS3 and PS4, respectively. prompt Same as PS1. PS1 The primary prompt string, printed before a command is read. the default is `%m%# '. It undergoes a special form of expansion before being displayed; see *Note Prompt Expansion::. PS2 The secondary prompt, printed when the shell needs more information to complete a command. It is expanded in the same way as PS1. The default is `%_> ', which displays any shell constructs or quotation marks which are currently being processed. PS3 Selection prompt used within a select loop. It is expanded in the same way as PS1. The default is `?# '. PS4 The execution trace prompt. Default is `+%N:%i> ', which displays the name of the current shell structure and the line number within it. In sh or ksh emulation, the default is `+ '. psvar (PSVAR ) An array (colon-separated list) whose first nine values can be used in PROMPT strings. Setting psvar also sets PSVAR, and vice versa. READNULLCMD The command name to assume if a single input redirection is specified with no command. Defaults to more. REPORTTIME If nonnegative, commands whose combined user and system execution times (measured in seconds) are greater than this value have timing statistics printed for them. REPLY This parameter is reserved by convention to pass string values between shell scripts and shell builtins in situations where a function call or redirection are impossible or undesirable. The read builtin and the select complex command may set REPLY, and filename generation both sets and examines its value when evaluating certain expressions. Some modules also employ REPLY for similar purposes. reply As REPLY, but for array values rather than strings. RPROMPT RPS1 This prompt is displayed on the right-hand side of the screen when the primary prompt is being displayed on the left. This does not work if the SINGLELINEZLE option is set. It is expanded in the same way as PS1. RPROMPT2 RPS2 This prompt is displayed on the right-hand side of the screen when the secondary prompt is being displayed on the left. This does not work if the SINGLELINEZLE option is set. It is expanded in the same way as PS2. SAVEHIST The maximum number of history events to save in the history file. SPROMPT The prompt used for spelling correction. The sequence `%R' expands to the string which presumably needs spelling correction, and `%r' expands to the proposed correction. All other prompt escapes are also allowed. STTY If this parameter is set in a command's environment, the shell runs the stty command with the value of this parameter as arguments in order to set up the terminal before executing the command. The modes apply only to the command, and are reset when it finishes or is suspended. If the command is suspended and continued later with the fg or wait builtins it will see the modes specified by STTY, as if it were not suspended. This (intentionally) does not apply if the command is continued via `kill -CONT'. STTY is ignored if the command is run in the background, or if it is in the environment of the shell but not explicitly assigned to in the input line. This avoids running stty at every external command by accidentally exporting it. Also note that STTY should not be used for window size specifications; these will not be local to the command. TERM The type of terminal in use. This is used when looking up termcap sequences. An assignment to TERM causes zsh to re-initialize the terminal, even if the value does not change (e.g., `TERM=$TERM'). It is necessary to make such an assignment upon any change to the terminal definition database or terminal type in order for the new settings to take effect. TIMEFMT The format of process time reports with the time keyword. The default is `%E real %U user %S system %P %J'. Recognizes the following escape sequences: %% A `%'. %U CPU seconds spent in user mode. %S CPU seconds spent in kernel mode. %E Elapsed time in seconds. %P The CPU percentage, computed as (%U+%S)/%E. %J The name of this job. A star may be inserted between the percent sign and flags printing time. This cause the time to be printed in `HH:MM:SS.TTT' format (hours and minutes are only printed if they are not zero). TMOUT If this parameter is nonzero, the shell will receive an ALRM signal if a command is not entered within the specified number of seconds after issuing a prompt. If there is a trap on SIGALRM, it will be executed and a new alarm is scheduled using the value of the TMOUT parameter after executing the trap. If no trap is set, and the idle time of the terminal is not less than the value of the TMOUT parameter, zsh terminates. Otherwise a new alarm is scheduled to TMOUT seconds after the last keypress. TMPPREFIX A pathname prefix which the shell will use for all temporary files. Note that this should include an initial part for the file name as well as any directory names. The default is `/tmp/zsh'. watch (WATCH ) An array (colon-separated list) of login/logout events to report. If it contains the single word `all', then all login/logout events are reported. If it contains the single word `notme', then all events are reported as with `all' except $USERNAME. An entry in this list may consist of a username, an `@' followed by a remote hostname, and a `%' followed by a line (tty). Any or all of these components may be present in an entry; if a login/logout event matches all of them, it is reported. WATCHFMT The format of login/logout reports if the watch parameter is set. Default is `%n has %a %l from %m'. Recognizes the following escape sequences: %n The name of the user that logged in/out. %a The observed action, i.e. "logged on" or "logged off". %l The line (tty) the user is logged in on. %M The full hostname of the remote host. %m The hostname up to the first `.'. If only the IP address is available or the utmp field contains the name of an X-windows display, the whole name is printed. _NOTE:_ The `%m' and `%M' escapes will work only if there is a host name field in the utmp on your machine. Otherwise they are treated as ordinary strings. %S (%s) Start (stop) standout mode. %U (%u) Start (stop) underline mode. %B (%b) Start (stop) boldface mode. %t %@ The time, in 12-hour, am/pm format. %T The time, in 24-hour format. %w The date in `DAY-DD' format. %W The date in `MM/DD/YY' format. %D The date in `YY-MM-DD' format. %(X:TRUE-TEXT:FALSE-TEXT) Specifies a ternary expression. The character following the X is arbitrary; the same character is used to separate the text for the "true" result from that for the "false" result. Both the separator and the right parenthesis may be escaped with a backslash. Ternary expressions may be nested. The test character X may be any one of `l', `n', `m' or `M', which indicate a `true' result if the corresponding escape sequence would return a non-empty value; or it may be `a', which indicates a `true' result if the watched user has logged in, or `false' if he has logged out. Other characters evaluate to neither true nor false; the entire expression is omitted in this case. If the result is `true', then the TRUE-TEXT is formatted according to the rules above and printed, and the FALSE-TEXT is skipped. If `false', the TRUE-TEXT is skipped and the FALSE-TEXT is formatted and printed. Either or both of the branches may be empty, but both separators must be present in any case. WORDCHARS A list of non-alphanumeric characters considered part of a word by the line editor. ZBEEP If set, this gives a string of characters, which can use all the same codes as the bindkey command as described in *Note The zsh/zle Module::, that will be output to the terminal instead of beeping. This may have a visible instead of an audible effect; for example, the string `\e[?5h\e[?5l' on a vt100 or xterm will have the effect of flashing reverse video on and off (if you usually use reverse video, you should use the string `\e[?5l\e[?5h' instead). This takes precedence over the NOBEEP option. ZDOTDIR The directory to search for shell startup files (.zshrc, etc), if not $HOME.  File: zsh.info, Node: Options, Next: Shell Builtin Commands, Prev: Parameters, Up: Top Options ******* * Menu: * Specifying Options:: * Description of Options:: * Option Aliases:: * Single Letter Options::  File: zsh.info, Node: Specifying Options, Next: Description of Options, Up: Options Specifying Options ================== Options are primarily referred to by name. These names are case insensitive and underscores are ignored. For example, `allexport' is equivalent to `A__lleXP_ort'. The sense of an option name may be inverted by preceding it with `no', so `setopt No_Beep' is equivalent to `unsetopt beep'. This inversion can only be done once, so `nonobeep' is _not_ a synonym for `beep'. Similarly, `tify' is not a synonym for `nonotify' (the inversion of `notify'). Some options also have one or more single letter names. There are two sets of single letter options: one used by default, and another used to emulate `sh'/`ksh' (used when the SH_OPTION_LETTERS option is set). The single letter options can be used on the shell command line, or with the set, setopt and unsetopt builtins, as normal Unix options preceded by `-'. The sense of the single letter options may be inverted by using `+' instead of `-'. Some of the single letter option names refer to an option being off, in which case the inversion of that name refers to the option being on. For example, `+n' is the short name of `exec', and `-n' is the short name of its inversion, `noexec'. In strings of single letter options supplied to the shell at startup, trailing whitespace will be ignored; for example the string `-f ' will be treated just as `-f', but the string `-f i' is an error. This is because many systems which implement the `#!' mechanism for calling scripts do not strip trailing whitespace.  File: zsh.info, Node: Description of Options, Next: Option Aliases, Prev: Specifying Options, Up: Options Description of Options ====================== In the following list, options set by default in all emulations are marked ; those set by default only in csh, ksh, sh, or zsh emulations are marked , , , as appropriate. When listing options (by `setopt', `unsetopt', `set -o' or `set +o'), those turned on by default appear in the list prefixed with `no'. Hence (unless KSH_OPTION_PRINT is set), `setopt' shows all options whose settings are changed from the default. ALIASES Expand aliases. ALL_EXPORT (-a, ksh: -a) All parameters subsequently defined are automatically exported. ALWAYS_LAST_PROMPT If unset, key functions that list completions try to return to the last prompt if given a numeric argument. If set these functions try to return to the last prompt if given _no_ numeric argument. ALWAYS_TO_END If a completion is performed with the cursor within a word, and a full completion is inserted, the cursor is moved to the end of the word. That is, the cursor is moved to the end of the word if either a single match is inserted or menu completion is performed. APPEND_HISTORY If this is set, zsh sessions will append their history list to the history file, rather than overwrite it. Thus, multiple parallel zsh sessions will all have their history lists added to the history file, in the order they are killed. AUTO_CD (-J) If a command is issued that can't be executed as a normal command, and the command is the name of a directory, perform the cd command to that directory. AUTO_CONTINUE With this option set, stopped jobs that are removed from the job table with the disown builtin command are automatically sent a CONT signal to make them running. AUTO_LIST (-9) Automatically list choices on an ambiguous completion. AUTO_MENU Automatically use menu completion after the second consecutive request for completion, for example by pressing the tab key repeatedly. This option is overridden by MENU_COMPLETE. AUTO_NAME_DIRS Any parameter that is set to the absolute name of a directory immediately becomes a name for that directory, that will be used by the `%~' and related prompt sequences, and will be available when completion is performed on a word starting with `~'. (Otherwise, the parameter must be used in the form `~PARAM' first.) AUTO_PARAM_KEYS If a parameter name was completed and a following character (normally a space) automatically inserted, and the next character typed is one of those that have to come directly after the name (like `}', `:', etc.), the automatically added character is deleted, so that the character typed comes immediately after the parameter name. Completion in a brace expansion is affected similarly: the added character is a `,', which will be removed if `}' is typed next. AUTO_PARAM_SLASH If a parameter is completed whose content is the name of a directory, then add a trailing slash instead of a space. AUTO_PUSHD (-N) Make cd push the old directory onto the directory stack. AUTO_REMOVE_SLASH When the last character resulting from a completion is a slash and the next character typed is a word delimiter, a slash, or a character that ends a command (such as a semicolon or an ampersand), remove the slash. AUTO_RESUME (-W) Treat single word simple commands without redirection as candidates for resumption of an existing job. BAD_PATTERN (+2) If a pattern for filename generation is badly formed, print an error message. (If this option is unset, the pattern will be left unchanged.) BANG_HIST (+K) Perform textual history expansion, `csh'-style, treating the character `!' specially. BARE_GLOB_QUAL In a glob pattern, treat a trailing set of parentheses as a qualifier list, if it contains no `|', `(' or (if special) `~' characters. See *Note Filename Generation::. BASH_AUTO_LIST On an ambiguous completion, automatically list choices when the completion function is called twice in succession. This takes precedence over AUTO_LIST. The setting of LIST_AMBIGUOUS is respected. If AUTO_MENU is set, the menu behaviour will then start with the third press. Note that this will not work with MENU_COMPLETE, since repeated completion calls immediately cycle through the list in that case. BEEP (+B) Beep on error in ZLE. BG_NICE (-6) Run all background jobs at a lower priority. This option is set by default. BRACE_CCL Expand expressions in braces which would not otherwise undergo brace expansion to a lexically ordered list of all the characters. See *Note Brace Expansion::. BSD_ECHO Make the echo builtin compatible with the BSD man page echo(1) command. This disables backslashed escape sequences in echo strings unless the -e option is specified. CASE_GLOB Make globbing (filename generation) sensitive to case. Note that other uses of patterns are always sensitive to case. If the option is unset, the presence of any character which is special to filename generation will cause case-insensitive matching. For example, cvs(/) can match the directory CVS owing to the presence of the globbing flag (unless the option BARE_GLOB_QUAL is unset). C_BASES Output hexadecimal numbers in the standard C format, for example `0xFF' instead of the usual `16#FF'. If the option OCTAL_ZEROES is also set (it is not by default), octal numbers will be treated similarly and hence appear as `077' instead of `8#77'. This option has no effect on the choice of the output base, nor on the output of bases other than hexadecimal and octal. Note that these formats will be understood on input irrespective of the setting of C_BASES. CDABLE_VARS (-T) If the argument to a cd command (or an implied cd with the AUTO_CD option set) is not a directory, and does not begin with a slash, try to expand the expression as if it were preceded by a `~' (see *Note Filename Expansion::). CHASE_DOTS When changing to a directory containing a path segment `..' which would otherwise be treated as canceling the previous segment in the path (in other words, `foo/..' would be removed from the path, or if `..' is the first part of the path, the last part of $PWD would be deleted), instead resolve the path to the physical directory. This option is overridden by CHASE_LINKS. For example, suppose /foo/bar is a link to the directory /alt/rod. Without this option set, `cd /foo/bar/..' changes to /foo; with it set, it changes to /alt. The same applies if the current directory is /foo/bar and `cd ..' is used. Note that all other symbolic links in the path will also be resolved. CHASE_LINKS (-w) Resolve symbolic links to their true values when changing directory. This also has the effect of CHASE_DOTS, i.e. a `..' path segment will be treated as referring to the physical parent, even if the preceding path segment is a symbolic link. CHECK_JOBS Report the status of background and suspended jobs before exiting a shell with job control; a second attempt to exit the shell will succeed. NO_CHECK_JOBS is best used only in combination with NO_HUP, else such jobs will be killed automatically. The check is omitted if the commands run from the previous command line included a `jobs' command, since it is assumed the user is aware that there are background or suspended jobs. A `jobs' command run from the precmd function is not counted for this purpose. CLOBBER (+C, ksh: +C) Allows `>' redirection to truncate existing files, and `>>' to create files. Otherwise `>!' or `>|' must be used to truncate a file, and `>>!' or `>>|' to create a file. COMPLETE_ALIASES Prevents aliases on the command line from being internally substituted before completion is attempted. The effect is to make the alias a distinct command for completion purposes. COMPLETE_IN_WORD If unset, the cursor is set to the end of the word if completion is started. Otherwise it stays there and completion is done from both ends. CORRECT (-0) Try to correct the spelling of commands. Note that, when the HASH_LIST_ALL option is not set or when some directories in the path are not readable, this may falsely report spelling errors the first time some commands are used. CORRECT_ALL (-O) Try to correct the spelling of all arguments in a line. CSH_JUNKIE_HISTORY A history reference without an event specifier will always refer to the previous command. Without this option, such a history reference refers to the same event as the previous history reference, defaulting to the previous command. CSH_JUNKIE_LOOPS Allow loop bodies to take the form `LIST; end' instead of `do LIST; done'. CSH_JUNKIE_QUOTES Changes the rules for single- and double-quoted text to match that of `csh'. These require that embedded newlines be preceded by a backslash; unescaped newlines will cause an error message. In double-quoted strings, it is made impossible to escape `$', ``' or `"' (and `\' itself no longer needs escaping). Command substitutions are only expanded once, and cannot be nested. CSH_NULLCMD Do not use the values of NULLCMD and READNULLCMD when running redirections with no command. This make such redirections fail (see *Note Redirection::). CSH_NULL_GLOB If a pattern for filename generation has no matches, delete the pattern from the argument list; do not report an error unless all the patterns in a command have no matches. Overrides NOMATCH. DVORAK Use the Dvorak keyboard instead of the standard qwerty keyboard as a basis for examining spelling mistakes for the CORRECT and CORRECT_ALL options and the spell-word editor command. EMACS If ZLE is loaded, turning on this option has the equivalent effect of `bindkey -e'. In addition, the VI option is unset. Turning it off has no effect. The option setting is not guaranteed to reflect the current keymap. This option is provided for compatibility; bindkey is the recommended interface. EQUALS Perform = filename expansion. (See *Note Filename Expansion::.) ERR_EXIT (-e, ksh: -e) If a command has a non-zero exit status, execute the ZERR trap, if set, and exit. This is disabled while running initialization scripts. cidnex(return from function, on error) ERR_RETURN If a command has a non-zero exit status, return immediately from the enclosing function. The logic is identical to that for ERR_EXIT, except that an implicit return statement is executed instead of an exit. This will trigger an exit at the outermost level of a non-interactive script. EXEC (+n, ksh: +n) Do execute commands. Without this option, commands are read and checked for syntax errors, but not executed. This option cannot be turned off in an interactive shell, except when `-n' is supplied to the shell at startup. EXTENDED_GLOB Treat the `#', `~' and `^' characters as part of patterns for filename generation, etc. (An initial unquoted `~' always produces named directory expansion.) EXTENDED_HISTORY Save each command's beginning timestamp (in seconds since the epoch) and the duration (in seconds) to the history file. The format of this prefixed data is: `:::'. FLOW_CONTROL If this option is unset, output flow control via start/stop characters (usually assigned to ^S/^Q) is disabled in the shell's editor. FUNCTION_ARGZERO When executing a shell function or sourcing a script, set $0 temporarily to the name of the function/script. GLOB (+F, ksh: +f) Perform filename generation (globbing). (See *Note Filename Generation::.) GLOBAL_EXPORT () If this option is set, passing the -x flag to the builtins declare, float, integer, readonly and typeset (but not local) will also set the -g flag; hence parameters exported to the environment will not be made local to the enclosing function, unless they were already or the flag +g is given explicitly. If the option is unset, exported parameters will be made local in just the same way as any other parameter. This option is set by default for backward compatibility; it is not recommended that its behaviour be relied upon. Note that the builtin export always sets both the -x and -g flags, and hence its effect extends beyond the scope of the enclosing function; this is the most portable way to achieve this behaviour. GLOBAL_RCS (-d) If this option is unset, the startup files /etc/zprofile, /etc/zshrc, /etc/zlogin and /etc/zlogout will not be run. It can be disabled and re-enabled at any time, including inside local startup files (.zshrc, etc.). GLOB_ASSIGN If this option is set, filename generation (globbing) is performed on the right hand side of scalar parameter assignments of the form `NAME=PATTERN (e.g. `foo=*'). If the result has more than one word the parameter will become an array with those words as arguments. This option is provided for backwards compatibility only: globbing is always performed on the right hand side of array assignments of the form `NAME=(VALUE)' (e.g. `foo=(*)') and this form is recommended for clarity; with this option set, it is not possible to predict whether the result will be an array or a scalar. GLOB_COMPLETE When the current word has a glob pattern, do not insert all the words resulting from the expansion but generate matches as for completion and cycle through them like MENU_COMPLETE. The matches are generated as if a `*' was added to the end of the word, or inserted at the cursor when COMPLETE_IN_WORD is set. This actually uses pattern matching, not globbing, so it works not only for files but for any completion, such as options, user names, etc. GLOB_DOTS (-4) Do not require a leading `.' in a filename to be matched explicitly. GLOB_SUBST Treat any characters resulting from parameter expansion as being eligible for file expansion and filename generation, and any characters resulting from command substitution as being eligible for filename generation. Braces (and commas in between) do not become eligible for expansion. HASH_CMDS Note the location of each command the first time it is executed. Subsequent invocations of the same command will use the saved location, avoiding a path search. If this option is unset, no path hashing is done at all. However, when CORRECT is set, commands whose names do not appear in the functions or aliases hash tables are hashed in order to avoid reporting them as spelling errors. HASH_DIRS Whenever a command name is hashed, hash the directory containing it, as well as all directories that occur earlier in the path. Has no effect if neither HASH_CMDS nor CORRECT is set. HASH_LIST_ALL Whenever a command completion is attempted, make sure the entire command path is hashed first. This makes the first completion slower. HIST_ALLOW_CLOBBER Add `|' to output redirections in the history. This allows history references to clobber files even when CLOBBER is unset. HIST_BEEP Beep when an attempt is made to access a history entry which isn't there. HIST_EXPIRE_DUPS_FIRST If the internal history needs to be trimmed to add the current command line, setting this option will cause the oldest history event that has a duplicate to be lost before losing a unique event from the list. You should be sure to set the value of HISTSIZE to a larger number than SAVEHIST in order to give you some room for the duplicated events, otherwise this option will behave just like HIST_IGNORE_ALL_DUPS once the history fills up with unique events. HIST_FIND_NO_DUPS When searching for history entries in the line editor, do not display duplicates of a line previously found, even if the duplicates are not contiguous. HIST_IGNORE_ALL_DUPS If a new command line being added to the history list duplicates an older one, the older command is removed from the list (even if it is not the previous event). HIST_IGNORE_DUPS (-h) Do not enter command lines into the history list if they are duplicates of the previous event. HIST_IGNORE_SPACE (-g) Remove command lines from the history list when the first character on the line is a space, or when one of the expanded aliases contains a leading space. Note that the command lingers in the internal history until the next command is entered before it vanishes, allowing you to briefly reuse or edit the line. If you want to make it vanish right away without entering another command, type a space and press return. HIST_NO_FUNCTIONS Remove function definitions from the history list. Note that the function lingers in the internal history until the next command is entered before it vanishes, allowing you to briefly reuse or edit the definition. HIST_NO_STORE Remove the history (fc -l) command from the history list when invoked. Note that the command lingers in the internal history until the next command is entered before it vanishes, allowing you to briefly reuse or edit the line. HIST_REDUCE_BLANKS Remove superfluous blanks from each command line being added to the history list. HIST_SAVE_NO_DUPS When writing out the history file, older commands that duplicate newer ones are omitted. HIST_VERIFY Whenever the user enters a line with history expansion, don't execute the line directly; instead, perform history expansion and reload the line into the editing buffer. HUP Send the HUP signal to running jobs when the shell exits. IGNORE_BRACES (-I) Do not perform brace expansion. IGNORE_EOF (-7) Do not exit on end-of-file. Require the use of exit or logout instead. However, ten consecutive EOFs will cause the shell to exit anyway, to avoid the shell hanging if its tty goes away. Also, if this option is set and the Zsh Line Editor is used, widgets implemented by shell functions can be bound to EOF (normally Control-D) without printing the normal warning message. This works only for normal widgets, not for completion widgets. INC_APPEND_HISTORY This options works like APPEND_HISTORY except that new history lines are added to the $HISTFILE incrementally (as soon as they are entered), rather than waiting until the shell is killed. The file is periodically trimmed to the number of lines specified by $SAVEHIST, but can exceed this value between trimmings. INTERACTIVE (-i, ksh: -i) This is an interactive shell. This option is set upon initialisation if the standard input is a tty and commands are being read from standard input. (See the discussion of SHIN_STDIN.) This heuristic may be overridden by specifying a state for this option on the command line. The value of this option cannot be changed anywhere other than the command line. INTERACTIVE_COMMENTS (-k) Allow comments even in interactive shells. KSH_ARRAYS Emulate `ksh' array handling as closely as possible. If this option is set, array elements are numbered from zero, an array parameter without subscript refers to the first element instead of the whole array, and braces are required to delimit a subscript (`${path[2]}' rather than just `$path[2]'). KSH_AUTOLOAD Emulate `ksh' function autoloading. This means that when a function is autoloaded, the corresponding file is merely executed, and must define the function itself. (By default, the function is defined to the contents of the file. However, the most common `ksh'-style case - of the file containing only a simple definition of the function - is always handled in the `ksh'-compatible manner.) KSH_GLOB In pattern matching, the interpretation of parentheses is affected by a preceding `@', `*', `+', `?' or `!'. See *Note Filename Generation::. KSH_OPTION_PRINT Alters the way options settings are printed: instead of separate lists of set and unset options, all options are shown, marked `on' if they are in the non-default state, `off' otherwise. KSH_TYPESET Alters the way arguments to the typeset family of commands, including declare, export, float, integer, local and readonly, are processed. Without this option, zsh will perform normal word splitting after command and parameter expansion in arguments of an assignment; with it, word splitting does not take place in those cases. LIST_AMBIGUOUS This option works when AUTO_LIST or BASH_AUTO_LIST is also set. If there is an unambiguous prefix to insert on the command line, that is done without a completion list being displayed; in other words, auto-listing behaviour only takes place when nothing would be inserted. In the case of BASH_AUTO_LIST, this means that the list will be delayed to the third call of the function. LIST_BEEP Beep on an ambiguous completion. More accurately, this forces the completion widgets to return status 1 on an ambiguous completion, which causes the shell to beep if the option BEEP is also set; this may be modified if completion is called from a user-defined widget. LIST_PACKED Try to make the completion list smaller (occupying less lines) by printing the matches in columns with different widths. LIST_ROWS_FIRST Lay out the matches in completion lists sorted horizontally, that is, the second match is to the right of the first one, not under it as usual. LIST_TYPES (-X) When listing files that are possible completions, show the type of each file with a trailing identifying mark. LOCAL_OPTIONS If this option is set at the point of return from a shell function, all the options (including this one) which were in force upon entry to the function are restored. Otherwise, only this option and the XTRACE and PRINT_EXIT_VALUE options are restored. Hence if this is explicitly unset by a shell function the other options in force at the point of return will remain so. A shell function can also guarantee itself a known shell configuration with a formulation like `emulate -L zsh'; the -L activates LOCAL_OPTIONS. LOCAL_TRAPS If this option is set when a signal trap is set inside a function, then the previous status of the trap for that signal will be restored when the function exits. Note that this option must be set _prior_ to altering the trap behaviour in a function; unlike LOCAL_OPTIONS, the value on exit from the function is irrelevant. However, it does not need to be set before any global trap for that to be correctly restored by a function. For example, unsetopt localtraps trap - INT fn() { setopt localtraps; trap '' INT; sleep 3; } will restore normally handling of SIGINT after the function exits. LOGIN (-l, ksh: -l) This is a login shell. If this option is not explicitly set, the shell is a login shell if the first character of the argv[0] passed to the shell is a `-'. LONG_LIST_JOBS (-R) List jobs in the long format by default. MAGIC_EQUAL_SUBST All unquoted arguments of the form `ANYTHING=EXPRESSION' appearing after the command name have filename expansion (that is, where EXPRESSION has a leading `~' or `=') performed on EXPRESSION as if it were a parameter assignment. The argument is not otherwise treated specially; it is passed to the command as a single argument, and not used as an actual parameter assignment. For example, in echo foo=~/bar:~/rod, both occurrences of ~ would be replaced. Note that this happens anyway with typeset and similar statements. This option respects the setting of the KSH_TYPESET option. In other words, if both options are in effect, arguments looking like assignments will not undergo wordsplitting. MAIL_WARNING (-U) Print a warning message if a mail file has been accessed since the shell last checked. MARK_DIRS (-8, ksh: -X) Append a trailing `/' to all directory names resulting from filename generation (globbing). MENU_COMPLETE (-Y) On an ambiguous completion, instead of listing possibilities or beeping, insert the first match immediately. Then when completion is requested again, remove the first match and insert the second match, etc. When there are no more matches, go back to the first one again. reverse-menu-complete may be used to loop through the list in the other direction. This option overrides AUTO_MENU. MONITOR (-m, ksh: -m) Allow job control. Set by default in interactive shells. MULTIOS Perform implicit `tee's or `cat's when multiple redirections are attempted (see *Note Redirection::). NOMATCH (+3) If a pattern for filename generation has no matches, print an error, instead of leaving it unchanged in the argument list. This also applies to file expansion of an initial `~' or `='. NOTIFY (-5, ksh: -b) Report the status of background jobs immediately, rather than waiting until just before printing a prompt. NULL_GLOB (-G) If a pattern for filename generation has no matches, delete the pattern from the argument list instead of reporting an error. Overrides NOMATCH. NUMERIC_GLOB_SORT If numeric filenames are matched by a filename generation pattern, sort the filenames numerically rather than lexicographically. OCTAL_ZEROES Interpret any integer constant beginning with a 0 as octal, per IEEE Std 1003.2-1992 (ISO 9945-2:1993). This is not enabled by default as it causes problems with parsing of, for example, date and time strings with leading zeroes. OVERSTRIKE Start up the line editor in overstrike mode. PATH_DIRS (-Q) Perform a path search even on command names with slashes in them. Thus if `/usr/local/bin' is in the user's path, and he or she types `X11/xinit', the command `/usr/local/bin/X11/xinit' will be executed (assuming it exists). Commands explicitly beginning with `/', `./' or `../' are not subject to the path search. This also applies to the . builtin. Note that subdirectories of the current directory are always searched for executables specified in this form. This takes place before any search indicated by this option, and regardless of whether `.' or the current directory appear in the command search path. POSIX_BUILTINS When this option is set the command builtin can be used to execute shell builtin commands. Parameter assignments specified before shell functions and special builtins are kept after the command completes unless the special builtin is prefixed with the command builtin. Special builtins are ., :, break, continue, declare, eval, exit, export, integer, local, readonly, return, set, shift, source, times, trap and unset. PRINT_EIGHT_BIT Print eight bit characters literally in completion lists, etc. This option is not necessary if your system correctly returns the printability of eight bit characters (see man page ctype(3)). PRINT_EXIT_VALUE (-1) Print the exit value of programs with non-zero exit status. PRIVILEGED (-p, ksh: -p) Turn on privileged mode. This is enabled automatically on startup if the effective user (group) ID is not equal to the real user (group) ID. Turning this option off causes the effective user and group IDs to be set to the real user and group IDs. This option disables sourcing user startup files. If zsh is invoked as `sh' or `ksh' with this option set, /etc/suid_profile is sourced (after /etc/profile on interactive shells). Sourcing ~/.profile is disabled and the contents of the ENV variable is ignored. This option cannot be changed using the -m option of setopt and unsetopt, and changing it inside a function always changes it globally regardless of the LOCAL_OPTIONS option. PROMPT_BANG If set, `!' is treated specially in prompt expansion. See *Note Prompt Expansion::. PROMPT_CR (+V) Print a carriage return just before printing a prompt in the line editor. This is on by default as multi-line editing is only possible if the editor knows where the start of the line appears. PROMPT_PERCENT If set, `%' is treated specially in prompt expansion. See *Note Prompt Expansion::. PROMPT_SUBST If set, _parameter expansion_, _command substitution_ and _arithmetic expansion_ are performed in prompts. PUSHD_IGNORE_DUPS Don't push multiple copies of the same directory onto the directory stack. PUSHD_MINUS Exchanges the meanings of `+' and `-' when used with a number to specify a directory in the stack. PUSHD_SILENT (-E) Do not print the directory stack after pushd or popd. PUSHD_TO_HOME (-D) Have pushd with no arguments act like `pushd $HOME'. RC_EXPAND_PARAM (-P) Array expansions of the form `FOO${XX}BAR', where the parameter XX is set to (A B C), are substituted with `FOOABAR FOOBBAR FOOCBAR' instead of the default `FOOA B CBAR'. RC_QUOTES Allow the character sequence `''' to signify a single quote within singly quoted strings. Note this does not apply in quoted strings using the format $'...', where a backslashed single quote can be used. RCS (+f) After /etc/zshenv is sourced on startup, source the .zshenv, /etc/zprofile, .zprofile, /etc/zshrc, .zshrc, /etc/zlogin, .zlogin, and .zlogout files, as described in *Note Files::. If this option is unset, the /etc/zshenv file is still sourced, but any of the others will not be; it can be set at any time to prevent the remaining startup files after the currently executing one from being sourced. REC_EXACT (-S) In completion, recognize exact matches even if they are ambiguous. RESTRICTED (-r) Enables restricted mode. This option cannot be changed using unsetopt, and setting it inside a function always changes it globally regardless of the LOCAL_OPTIONS option. See *Note Restricted Shell::. RM_STAR_SILENT (-H) Do not query the user before executing `rm *' or `rm path/*'. RM_STAR_WAIT If querying the user before executing `rm *' or `rm path/*', first wait ten seconds and ignore anything typed in that time. This avoids the problem of reflexively answering `yes' to the query when one didn't really mean it. The wait and query can always be avoided by expanding the `*' in ZLE (with tab). SHARE_HISTORY This option both imports new commands from the history file, and also causes your typed commands to be appended to the history file (the latter is like specifying INC_APPEND_HISTORY). The history lines are also output with timestamps ala EXTENDED_HISTORY (which makes it easier to find the spot where we left off reading the file after it gets re-written). By default, history movement commands visit the imported lines as well as the local lines, but you can toggle this on and off with the set-local-history zle binding. It is also possible to create a zle widget that will make some commands ignore imported commands, and some include them. If you find that you want more control over when commands get imported, you may wish to turn SHARE_HISTORY off, INC_APPEND_HISTORY on, and then manually import commands whenever you need them using `fc -RI'. SH_FILE_EXPANSION Perform filename expansion (e.g., ~ expansion) _before_ parameter expansion, command substitution, arithmetic expansion and brace expansion. If this option is unset, it is performed _after_ brace expansion, so things like `~$USERNAME' and `~{pfalstad,rc}' will work. SH_GLOB Disables the special meaning of `(', `|', `)' and '<' for globbing the result of parameter and command substitutions, and in some other places where the shell accepts patterns. This option is set by default if zsh is invoked as sh or ksh. SHIN_STDIN (-s, ksh: -s) Commands are being read from the standard input. Commands are read from standard input if no command is specified with -c and no file of commands is specified. If SHIN_STDIN is set explicitly on the command line, any argument that would otherwise have been taken as a file to run will instead be treated as a normal positional parameter. Note that setting or unsetting this option on the command line does not necessarily affect the state the option will have while the shell is running - that is purely an indicator of whether on not commands are _actually_ being read from standard input. The value of this option cannot be changed anywhere other than the command line. SH_NULLCMD Do not use the values of NULLCMD and READNULLCMD when doing redirections, use `:' instead (see *Note Redirection::). SH_OPTION_LETTERS If this option is set the shell tries to interpret single letter options (which are used with set and setopt) like `ksh' does. This also affects the value of the - special parameter. SHORT_LOOPS Allow the short forms of for, repeat, select, if, and function constructs. SH_WORD_SPLIT (-y) Causes field splitting to be performed on unquoted parameter expansions. Note that this option has nothing to do with word splitting. (See *Note Parameter Expansion::.) SINGLE_COMMAND (-t, ksh: -t) If the shell is reading from standard input, it exits after a single command has been executed. This also makes the shell non-interactive, unless the INTERACTIVE option is explicitly set on the command line. The value of this option cannot be changed anywhere other than the command line. SINGLE_LINE_ZLE (-M) Use single-line command line editing instead of multi-line. SUN_KEYBOARD_HACK (-L) If a line ends with a backquote, and there are an odd number of backquotes on the line, ignore the trailing backquote. This is useful on some keyboards where the return key is too small, and the backquote key lies annoyingly close to it. TRANSIENT_RPROMPT Remove any right prompt from display when accepting a command line. This may be useful with terminals with other cut/paste methods. TYPESET_SILENT If this is unset, executing any of the `typeset' family of commands with no options and a list of parameters that have no values to be assigned but already exist will display the value of the parameter. If the option is set, they will only be shown when parameters are selected with the `-m' option. The option `-p' is available whether or not the option is set. UNSET (+u, ksh: +u) Treat unset parameters as if they were empty when substituting. Otherwise they are treated as an error. VERBOSE (-v, ksh: -v) Print shell input lines as they are read. VI If ZLE is loaded, turning on this option has the equivalent effect of `bindkey -v'. In addition, the EMACS option is unset. Turning it off has no effect. The option setting is not guaranteed to reflect the current keymap. This option is provided for compatibility; bindkey is the recommended interface. XTRACE (-x, ksh: -x) Print commands and their arguments as they are executed. ZLE (-Z) Use the zsh line editor. Set by default in interactive shells connected to a terminal.  File: zsh.info, Node: Option Aliases, Next: Single Letter Options, Prev: Description of Options, Up: Options Option Aliases ============== Some options have alternative names. These aliases are never used for output, but can be used just like normal option names when specifying options to the shell. BRACE_EXPAND _NO__IGNORE_BRACES (ksh and bash compatibility) DOT_GLOB GLOB_DOTS (bash compatibility) HASH_ALL HASH_CMDS (bash compatibility) HIST_APPEND APPEND_HISTORY (bash compatibility) HIST_EXPAND BANG_HIST (bash compatibility) LOG _NO__HIST_NO_FUNCTIONS (ksh compatibility) MAIL_WARN MAIL_WARNING (bash compatibility) ONE_CMD SINGLE_COMMAND (bash compatibility) PHYSICAL CHASE_LINKS (ksh and bash compatibility) PROMPT_VARS PROMPT_SUBST (bash compatibility) STDIN SHIN_STDIN (ksh compatibility) TRACK_ALL HASH_CMDS (ksh compatibility)  File: zsh.info, Node: Single Letter Options, Prev: Option Aliases, Up: Options Single Letter Options ===================== Default set ----------- -0 CORRECT -1 PRINT_EXIT_VALUE -2 _NO__BAD_PATTERN -3 _NO__NOMATCH -4 GLOB_DOTS -5 NOTIFY -6 BG_NICE -7 IGNORE_EOF -8 MARK_DIRS -9 AUTO_LIST -B _NO__BEEP -C _NO__CLOBBER -D PUSHD_TO_HOME -E PUSHD_SILENT -F _NO__GLOB -G NULL_GLOB -H RM_STAR_SILENT -I IGNORE_BRACES -J AUTO_CD -K _NO__BANG_HIST -L SUN_KEYBOARD_HACK -M SINGLE_LINE_ZLE -N AUTO_PUSHD -O CORRECT_ALL -P RC_EXPAND_PARAM -Q PATH_DIRS -R LONG_LIST_JOBS -S REC_EXACT -T CDABLE_VARS -U MAIL_WARNING -V _NO__PROMPT_CR -W AUTO_RESUME -X LIST_TYPES -Y MENU_COMPLETE -Z ZLE -a ALL_EXPORT -e ERR_EXIT -f _NO__RCS -g HIST_IGNORE_SPACE -h HIST_IGNORE_DUPS -i INTERACTIVE -k INTERACTIVE_COMMENTS -l LOGIN -m MONITOR -n _NO__EXEC -p PRIVILEGED -r RESTRICTED -s SHIN_STDIN -t SINGLE_COMMAND -u _NO__UNSET -v VERBOSE -w CHASE_LINKS -x XTRACE -y SH_WORD_SPLIT sh/ksh emulation set -------------------- -C _NO__CLOBBER -X MARK_DIRS -a ALL_EXPORT -b NOTIFY -e ERR_EXIT -f _NO__GLOB -i INTERACTIVE -l LOGIN -m MONITOR -n _NO__EXEC -p PRIVILEGED -r RESTRICTED -s SHIN_STDIN -t SINGLE_COMMAND -u _NO__UNSET -v VERBOSE -x XTRACE Also note --------- -A Used by set for setting arrays -b Used on the command line to specify end of option processing -c Used on the command line to specify a single command -m Used by setopt for pattern-matching option setting -o Used in all places to allow use of long option names -s Used by set to sort positional parameters