ZSHPARAM(1)ZSHPARAM(1)NAMEzshparam - zsh 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 `*', `@', `#', `?', `-', `$', or `!'. The value may
be a scalar (a string), an integer, an array (indexed numerically), or
an associative array (an unordered set of name-value pairs, indexed by
name). To assign a scalar or integer value to a parameter, use the
typeset builtin. To assign an array value, use `set -A name value
...'. The value of a parameter may also be assigned by writing:
name=value
If the integer attribute, -i, is set for name, the value is subject to
arithmetic evaluation. See the section `Array Parameters' for addi‐
tional forms of assignment.
In the parameter lists that follow, the mark `<S>' indicates that the
parameter is special. Special parameters cannot have their type
changed, and they stay special even if unset. `<Z>' indicates that the
parameter does not exist when the shell initializes in sh or ksh emula‐
tion mode.
ARRAY PARAMETERS
The value of an array parameter may be assigned by writing:
name=(value ...)
If no parameter name exists, an ordinary array parameter is created.
Associative arrays must be declared first, by `typeset -A name'. When
name refers to an associative array, the parenthesized list is inter‐
preted as alternating keys and values:
name=(key value ...)
Every key must have a value in this case. To create an empty array or
associative array, use:
name=()
Individual elements of an array may be selected using a subscript. A
subscript of the form `[exp]' selects the single element exp, where exp
is an arithmetic expression which will be subject to arithmetic expan‐
sion as if it were surrounded by `$((...))'. The elements are numbered
beginning with 1 unless the KSH_ARRAYS option is set when they are num‐
bered from zero.
The same subscripting syntax is used for associative arrays, except
that no arithmetic expansion is applied to exp.
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. (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 $FOO[2,5]' prints `ooba'.
Subscripts may be used inside braces used to delimit a parameter name,
thus `${foo[2]}' is equivalent to `$foo[2]'. If the KSH_ARRAYS option
is set, the braced form is the only one that will work, the subscript
otherwise not being treated specially.
If a subscript is used on the left side of an assignment the selected
element or range is replaced by the expression on the right side. An
array (but not an associative array) may be created by assignment to a
range or element. Arrays do not nest, so assigning a parenthesized
list of values to an element or range changes the number of elements in
the array, shifting the other elements to accommodate the new values.
(This is not supported for associative arrays.)
To delete an element of an ordinary array, assign `()' to that element.
To delete an element of an associative array, use the unset command.
If the opening bracket or the comma is directly followed by an opening
parentheses the string up to the matching closing one is considered to
be a list of flags. The flags currently understood are:
w If the parameter subscripted is a scalar than this flag makes
subscripting work on words instead of characters. The default
word separator is whitespace.
s:string:
This gives the string that separates words (for use with the w
flag).
p Recognize the same escape sequences as the print builtin in the
string argument of a subsequent `s' flag.
f If the parameter subscripted is a scalar than this flag makes
subscripting work on lines instead of characters, i.e. with ele‐
ments separated by newlines. This is a shorthand for `pws:\n:'.
r Reverse subscripting: if this flag is given, the exp is taken
as a pattern and the result is the first matching array ele‐
ment, substring or word (if the parameter is an array, if it is
a scalar, or if it is a scalar and the `w' flag is given,
respectively). The subscript used is the number of the matching
element, so that pairs of subscripts such as `$foo[(r)??,3]' and
`$foo[(r)??,(r)f*]' are possible. If the parameter is an asso‐
ciative array, only the value part of each pair is compared to
the pattern.
R Like `r', but gives the last match. For associative arrays,
gives all possible matches.
k If used in a subscript on a parameter that is not an associative
array, this behaves like `r', but if used on an association, it
makes the keys be interpreted as patterns and returns the first
value whose key matches the exp.
K On an association this is like `k' but returns all values whose
keys match the exp. On other types of parameters this has the
same effect as `R'.
i like `r', but gives the index of the match instead; this may not
be combined with a second argument. For associative arrays, the
key part of each pair is compared to the pattern, and the first
matching key found is used.
I like `i', but gives the index of the last match, or all possible
matching keys in an associative array.
n:expr:
if combined with `r', `R', `i' or `I', makes them give the nth
or nth last match (if expr evaluates to n). This flag is
ignored when the array is associative.
b:expr:
if combined with `r', `R', `i' or `I', makes them begin at the
nth or nth last element, word, or character (if expr evaluates
to n). This flag is ignored when the array is associative.
e This option has no effect and retained for backward compatibil‐
ity only.
POSITIONAL PARAMETERS
The positional parameters provide access to the command-line arguments
of a shell function, shell script, or the shell itself; see the section
`Invocation', and also the section `Functions'. The parameter n, where
n is a number, is the nth positional parameter. The parameters *, @
and argv are arrays containing all the positional parameters; thus
`$argv[n]', etc., is equivalent to simply `$n'.
Positional parameters may be changed after the shell or function starts
by using the set builtin, by assigning to the argv array, or by direct
assignment of the form `n=value' where n is the number of the posi‐
tional parameter to be changed. This also creates (with empty values)
any of the positions from 1 to n that do not already have values. Note
that, because the positional parameters form an array, an array assign‐
ment of the form `n=(value ...)' is allowed, and has the effect of
shifting all the values at positions greater than n by as many posi‐
tions as necessary to accommodate the new values.
LOCAL PARAMETERS
Shell function executions delimit scopes for shell parameters. (Param‐
eters are dynamically scoped.) The typeset builtin, and its alterna‐
tive forms declare, integer, local and readonly (but not export), can
be used to declare a parameter as being local to the innermost scope.
When a parameter is read or assigned to, the innermost existing parame‐
ter of that name is used. (That is, the local parameter hides any
less-local parameter.) However, assigning to a non-existent parameter,
or declaring a new parameter with export, causes it to be created in
the outermost scope.
Local parameters disappear when their scope ends. unset can be used to
delete a parameter while it is still in scope; any outer parameter of
the same name remains hidden.
Special parameters may also be made local; they retain their special
attributes unless either the existing or the newly-created parameter
has the -h (hide) attribute. This may have unexpected effects: there
is no default value, so if there is no assignment at the point the
variable is made local, it will be set to an empty value (or zero in
the case of integers). The following:
typeset PATH=/new/directory:$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 parame‐
ters were never exported has been removed.
PARAMETERS SET BY THE SHELL
The following parameters are automatically set by the shell:
! <S> The process ID of the last background command invoked.
# <S> The number of positional parameters in decimal.
ARGC <S> <Z>
Same as #.
$ <S> The process ID of this shell.
- <S> Flags supplied to the shell on invocation or by the set or
setopt commands.
* <S> An array containing the positional parameters.
argv <S> <Z>
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).
@ <S> Same as argv[@], even when argv is not set.
? <S> The exit value returned by the last command.
0 <S> The name used to invoke the current shell. If the FUNC‐
TION_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 <S> <Z>
Same as ?.
pipestatus <S> <Z>
An array containing the exit values returned by all commands in
the last pipeline.
_ <S> 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 <S>
The effective group ID of the shell process. If you have suffi‐
cient 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 <S>
The effective user ID of the shell process. If you have suffi‐
cient 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 <S>
The value of errno (see errno(3)) as set by the most recently
failed system call. This value is system dependent and is
intended for debugging purposes.
GID <S>
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 privi‐
leges), you may start a single command under a different group
ID by `(GID=gid; command)'
HOST The current hostname.
LINENO <S>
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 func‐
tions 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 ini‐
tializes and whenever the directory changes.
OPTARG <S>
The value of the last option argument processed by the getopts
command.
OPTIND <S>
The index of the last option argument processed by the getopts
command.
OSTYPE The operating system, as determined at compile time.
PPID <S>
The process ID of the parent of the shell.
PWD The present working directory. This is set when the shell ini‐
tializes and whenever the directory changes.
RANDOM <S>
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 <S>
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 <S>
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 <S>
The idle time of the tty associated with the shell in seconds or
-1 if there is no such tty.
UID <S>
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 <S>
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 privi‐
leges), you may start a single command under a different user‐
name (and user ID and group ID) by `(USERNAME=username; com‐
mand)'
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.
PARAMETERS USED BY THE SHELL
The following parameters are used by the shell:
ARGV0 If exported, its value is used as the argv[0] of external com‐
mands. Usually used in constructs like `ARGV0=emacs nethack'.
BAUD The baud rate of the current connection. Used by the line edi‐
tor update mechanism to compensate for a slow terminal by delay‐
ing 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 parame‐
ter 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 <S> <Z> (CDPATH <S>)
An array (colon-separated list) of directories specifying the
search path for the cd command.
COLUMNS <S>
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 <S> <Z> (FIGNORE <S>)
An array (colon separated list) containing the suffixes of files
to be ignored during filename completion. However, if the com‐
pletion generates only files which would match if this variable
would be ignored, than these files are completed anyway.
fpath <S> <Z> (FPATH <S>)
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 exe‐
cutable file is found, then it is read and executed in the cur‐
rent environment.
histchars <S>
Three characters used by the shell's history and lexical analy‐
sis mechanism. The first character signals the start of a his‐
tory expansion (default `!'). The second character signals the
start of a quick history substitution (default `^'). The third
character is the comment character (default `#').
HISTCHARS <S> <Z>
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 <S>
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 dif‐
ference as a cushion for saving duplicated history events.
HOME <S>
The default argument for the cd command.
IFS <S>
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 <S>
This variable determines the locale category for any category
not specifically selected via a variable starting with `LC_'.
LC_ALL <S>
This variable overrides the value of the `LANG' variable and the
value of any of the other variables starting with `LC_'.
LC_COLLATE <S>
This variable determines the locale category for character col‐
lation information within ranges in glob brackets and for sort‐
ing.
LC_CTYPE <S>
This variable determines the locale category for character han‐
dling functions.
LC_MESSAGES <S>
This variable determines the language in which messages should
be written. Note that zsh does not use message catalogs.
LC_NUMERIC <S>
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 <S>
This variable determines the locale category for date and time
formatting in prompt escape sequences.
LINES <S>
The number of lines for this terminal session. Used for print‐
ing 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 <S> <Z> (MAILPATH <S>)
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
$_ defined as the name of the file that has changed. The
default message is `You have new mail'. If an element is a
directory instead of a file the shell will recursively check
every file in every subdirectory of the element.
manpath <S> <Z> (MANPATH <S> <Z>)
An array (colon-separated list) whose value is not used by the
shell. The manpath array can be useful, however, since setting
it also sets MANPATH, and vice versa.
module_path <S> <Z> (MODULE_PATH <S>)
An array (colon-separated list) of directories that zmodload
searches for dynamically loadable modules. This is initialized
to a standard pathname, usually `/usr/local/lib/zsh/$ZSH_VER‐
SION'. (The `/usr/local/lib' part varies from installation to
installation.) For security reasons, any value set in the envi‐
ronment when the shell is started will be ignored.
These parameters only exist if the installation supports dynamic
module loading.
NULLCMD <S>
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 <S> <Z> (PATH <S>)
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 <S>
This string is output whenever the line editor exits. It usu‐
ally contains termcap strings to reset the terminal.
PS1 <S>
The primary prompt string, printed before a command is read.
the default is `%m%# '. It undergoes a special form of expan‐
sion before being displayed; see the section `Prompt Expansion'.
PS2 <S>
The secondary prompt, printed when the shell needs more informa‐
tion 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 <S>
Selection prompt used within a select loop. It is expanded in
the same way as PS1. The default is `?# '.
PS4 <S>
The execution trace prompt. Default is `+%N:%i> ', which dis‐
plays the name of the current shell structure and the line num‐
ber within it. In sh or ksh emulation, the default is `+ '.
PROMPT <S> <Z>
PROMPT2 <S> <Z>
PROMPT3 <S> <Z>
PROMPT4 <S> <Z>
Same as PS1, PS2, PS3 and PS4, respectively.
psvar <S> <Z> (PSVAR <S>)
An array (colon-separated list) whose first nine values can be
used in PROMPT strings. Setting psvar also sets PSVAR, and vice
versa.
prompt <S> <Z>
Same as PS1.
READNULLCMD <S>
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 execu‐
tion times (measured in seconds) are greater than this value
have timing statistics printed for them.
RPROMPT <S>
RPS1 <S>
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.
SAVEHIST
The maximum number of history events to save in the history
file.
SPROMPT <S>
The prompt used for spelling correction. The sequence `%R'
expands to the string which presumably needs spelling correc‐
tion, 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 argu‐
ments in order to set up the terminal before executing the com‐
mand. The modes apply only to the command, and are reset when it
finishes or is suspended. If the command is suspended and con‐
tinued later with the fg or wait builtins it will see the modes
specified by STTY, as if it were not suspended. This (inten‐
tionally) does not apply if the command is continued via `kill
-CONT'. STTY is ignored if the command is run in the back‐
ground, 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 specifi‐
cations; these will not be local to the command.
TERM <S>
The type of terminal in use. This is used when looking up term‐
cap sequences.
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 print‐
ing 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. Other‐
wise 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 <S> <Z> (WATCH <S>)
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 follow‐
ing 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. Other‐
wise 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 sepa‐
rate the text for the "true" result from that for the
"false" result. Both the separator and the right paren‐
thesis may be escaped with a backslash. Ternary expres‐
sions 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 <S>
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 the zsh/zle
module entry in zshmodules(1), that will be output to the termi‐
nal 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.
zsh 3.1.9 June 5, 2000 ZSHPARAM(1)
