ZSHPARAM(1) manual page

Table of Contents

A parameter has a name, a value, and a number of attributes. A name may be any sequence of alphanumeric characters and _'s, or the single characters *, @, #, ?, -, $, or !. The value may be either a scalar (a string), an integer, or an array. To assign a scalar or integer value to a parameter, use the typeset builtin. To assign an array value, use set -A name value .... The value of a 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.

The value of an array parameter may be assigned by writing:

name=(value ...) ...

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 "$((...))". The elements are numbered beginning with 1. A subscript of the form [*] or [@] evaluates to all elements of an array; there is no difference between the two except when they appear within double quotes. "$foo[*]" evaluates to "$foo[1] $foo[2] ...", while "$foo[@]" evaluates to "$foo[1]" "$foo[2]", etc. A subscript of the form [exp1,exp2] selects all elements in the range exp1 to exp2, inclusive. 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.

If a subscript is used on the left side of an assignment the selected range is replaced by the expression on the right side.

If the opening bracket or the comma is directly followed by an opening parentheses the string up to the matching closing one is considered to be a list of flags. The flags currently understood are:

e
the argument is expanded using full shell expansion first
w
if the parameter subscripted is a scalar than this flag makes subscription work on a per-word basis instead of characters
s:string:
this gives the string that separates words (for use with the w flag)
r
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); note that this is like giving a number: $foo[(r)??,3] and $foo[(r)??,(r)f*] work
R
like r, but gives the last match
i
like r, but gives the index of the match instead; this may not be combined with a second argument
I
like i, but gives the index of the last match
n:expr:
if combined with r, R, , or I, makes them give the n'th or n'th last match (if expr evaluates to n)

Positional Parameters

Positional parameters are set by the shell on invocation, by the set builtin, or by direct assignment. 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.

Special Parameters

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.
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 *.
@
Same as argv[@].
?
The exit value returned by the last command.
status
Same as ?.
_
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.
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=egid 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=euid command

ERRNO: The value of errno as set by the most recently failed system call. This value is system dependent and is intended for debugging purposes.
GID: The 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.
HOSTTYPE: A string corresponding to the type of the host the shell is running on. This variable is obselete and may be removed in a future version.
LINENO: The line number of the current line within the current script being executed.
LOGNAME: The username corresponding to the user id of the shell process at the time of login.
MACHTYPE: The machine type (microprocessor class or machine model), as determined at compile time.
OLDPWD: The previous working directory.
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.
RANDOM: A 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.
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.
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.
UID: The 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 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.

The following parameters are used by the shell:

ARGV0
If exported, it's value is used as 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.
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. But if the completion generates only files which would match if this variable would be ignored, than 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 substitution (default `!'). The second character signals the start of a quick history substitution (default `^'). The third character is the comment character (default `#').
HISTFILE
The file to save the history in when an interactive shell exits. If unset, the history is not saved.
HISTSIZE
The maximum size of the history list.
HOME
The default argument for the cd command.
IFS
Internal field separators, normally space, tab, and newline, that are used to separate words which result from command or parameter substitution and words read by the read builtin.
KEYTIMEOUT
The time the shell waits, in hundredths of seconds, for another key to be pressed when reading bound multi-character 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 filenames to list without asking first. If set to zero, the shell asks only if the top of the listing would scroll off the screen.
LITHISTSIZE
The maximum size of the literal history list (before history expansion).
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. By default it is set to the user's system mailbox.
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 sequence $_ in the message will be replaced by the name of the mail file. 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.
NULLCMD
The command name to assume if a redirection is specified with no command. Defaults to cat. For sh/ksh-like 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
The primary prompt string, printed before a command is read; the default is "%m%# ". If the escape sequence takes an optional integer, it should appear between the '%' and the next character of the sequence. The following escape sequences are recognized:

%d
%/
Present working directory ($PWD).
%~
$PWD. If it 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 ~.
%c
%.
%C
Trailing component of $PWD. An integer may follow the '%' to get more than one component. Unless %C is used, tilde expansion is performed first.
!
%h
%!
Current history event number
%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.
%S (%s)
Start (stop) standout mode.
%U (%u)
Start (stop) underline mode.
%B (%b)
Start (stop) boldface mode.
%t
%@
Current time of day, in 12-hour, am/pm format.
%T
Current time of day, in 24-hour format.
%*
Current time of day in 24-hour format, with seconds.
%n
$USERNAME.
%w
The date in day-dd format.
%W
The date in mm/dd/yy format.
%D
The date in yy-mm-dd format.
%D{string}
string is formatted using the strftime function. See strftime(3) for more details, if your system has it.
%l
The line (tty) the user is logged in on.
%?
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.
%E
Clears to end of line.
%#
A '#' if the shell is running as root, a '%' if not. Equivalent to %(#.#.%%).
%v
The value of the first element of the $psvar array parameter. Following the '%' with an integer gives that element of the array.
%{...%}
Include a string as a literal escape sequence. The string within the braces should not change the cursor position.
%(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. 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. The test character x may be any of the following:

c
.
~
True if the current path, with prefix replacement, has at least n elements.
/
C
True if the current absolute path has at least n elements.
t
True if the time in minutes is equal to n.
T
True if the time in hours is equal to n.
d
True if the day of the month is equal to n.
D
True if the month is equal to n (January = 0).
w
True if the day of the week is equal to n (Sunday = 0).
?
True if the exit status of the last command was n.
#
True if the effective uid of the current process is n.
g
True if the effective gid of the current process is n.
L
True if the SHLVL parameter is at least n.
S
True if the SECONDS parameter is at least n.
v
True if the array psvar has at least n elements.
_
True if at least n shell constructs were started.

PROMPT2
The secondary prompt, printed when the shell needs more information to complete a command. Recognizes the same escape sequences as $PROMPT. The default is "> ".
PROMPT3
Selection prompt used within a select loop. Recognizes the same escape sequences as $PROMPT. The default is "?# ".
PROMPT4
The execution trace prompt. Default is "+ ".
PS1
PS2
PS3
PS4
Same as PROMPT, PROMPT2, PROMPT3, and PROMPT4, respectively.
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.
prompt
Same as PROMPT.
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.
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. Recognizes the same escape sequences as PROMPT.
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.
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:

%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 terminate if a command is not entered within the specified number of seconds after issuing a prompt.
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 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 nonalphanumeric characters considered part of a word by the line editor.
ZDOTDIR
The directory to search for shell startup files (.zshrc, etc), if not $HOME.
Table of Contents
NAME
DESCRIPTIONS
Positional Parameters
Special Parameters
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