1ZSHMISC(1) General Commands Manual ZSHMISC(1)
2
6 zshmisc - everything and then some
7
9 A simple command is a sequence of optional parameter assignments fol‐
10 lowed by blank-separated words, with optional redirections inter‐
11 spersed. The first word is the command to be executed, and the remain‐
12 ing words, if any, are arguments to the command. If a command name is
13 given, the parameter assignments modify the environment of the command
14 when it is executed. The value of a simple command is its exit status,
15 or 128 plus the signal number if terminated by a signal. For example,
16 echo foo
18 is a simple command with arguments.
20 A pipeline is either a simple command, or a sequence of two or more
22 simple commands where each command is separated from the next by `|' or
23 `|&'. Where commands are separated by `|', the standard output of the
24 first command is connected to the standard input of the next. `|&' is
25 shorthand for `2>&1 |', which connects both the standard output and the
26 standard error of the command to the standard input of the next. The
27 value of a pipeline is the value of the last command, unless the pipe‐
28 line is preceded by `!' in which case the value is the logical inverse
29 of the value of the last command. For example,
30 echo foo | sed 's/foo/bar/'
32 is a pipeline, where the output (`foo' plus a newline) of the first
34 command will be passed to the input of the second.
35 If a pipeline is preceded by `coproc', it is executed as a coprocess; a
37 two-way pipe is established between it and the parent shell. The shell
38 can read from or write to the coprocess by means of the `>&p' and `<&p'
39 redirection operators or with `print -p' and `read -p'. A pipeline
40 cannot be preceded by both `coproc' and `!'. If job control is active,
41 the coprocess can be treated in other than input and output as an ordi‐
42 nary background job.
43 A sublist is either a single pipeline, or a sequence of two or more
45 pipelines separated by `&&' or `||'. If two pipelines are separated by
46 `&&', the second pipeline is executed only if the first succeeds
47 (returns a zero value). If two pipelines are separated by `||', the
48 second is executed only if the first fails (returns a nonzero value).
49 Both operators have equal precedence and are left associative. The
50 value of the sublist is the value of the last pipeline executed. For
51 example,
52 dmesg | grep panic && print yes
54 is a sublist consisting of two pipelines, the second just a simple com‐
56 mand which will be executed if and only if the grep command returns a
57 zero value. If it does not, the value of the sublist is that return
58 value, else it is the value returned by the print (almost certainly
59 zero).
60 A list is a sequence of zero or more sublists, in which each sublist is
62 terminated by `;', `&', `&|', `&!', or a newline. This terminator may
63 optionally be omitted from the last sublist in the list when the list
64 appears as a complex command inside `(...)' or `{...}'. When a sub‐
65 list is terminated by `;' or newline, the shell waits for it to finish
66 before executing the next sublist. If a sublist is terminated by a
67 `&', `&|', or `&!', the shell executes the last pipeline in it in the
68 background, and does not wait for it to finish (note the difference
69 from other shells which execute the whole sublist in the background).
70 A backgrounded pipeline returns a status of zero.
71 More generally, a list can be seen as a set of any shell commands what‐
73 soever, including the complex commands below; this is implied wherever
74 the word `list' appears in later descriptions. For example, the com‐
75 mands in a shell function form a special sort of list.
76
78 A simple command may be preceded by a precommand modifier, which will
79 alter how the command is interpreted. These modifiers are shell
80 builtin commands with the exception of nocorrect which is a reserved
81 word.
82 - The command is executed with a `-' prepended to its argv[0]
84 string.
85 noglob Filename generation (globbing) is not performed on any of the
87 words.
88 nocorrect
90 Spelling correction is not done on any of the words. This must
91 appear before any other precommand modifier, as it is inter‐
92 preted immediately, before any parsing is done. It has no
93 effect in non-interactive shells.
94 exec The command is executed in the parent shell without forking.
96 command
98 The command word is taken to be the name of an external command,
99 rather than a shell function or builtin.
100 builtin
102 The command word is taken to be the name of a builtin command,
103 rather than a shell function or external command.
104
106 A complex command in zsh is one of the following:
107 if list then list [ elif list then list ] ... [ else list ] fi
109 The if list is executed, and if it returns a zero exit status,
110 the then list is executed. Otherwise, the elif list is executed
111 and if its value is zero, the then list is executed. If each
112 elif list returns nonzero, the else list is executed.
113 for name ... [ in word ... ] term do list done
115 where term is at least one newline or ;. Expand the list of
116 words, and set the parameter name to each of them in turn, exe‐
117 cuting list each time. If the in word is omitted, use the posi‐
118 tional parameters instead of the words.
119 More than one parameter name can appear before the list of
121 words. If N names are given, then on each execution of the loop
122 the next N words are assigned to the corresponding parameters.
123 If there are more names than remaining words, the remaining
124 parameters are each set to the empty string. Execution of the
125 loop ends when there is no remaining word to assign to the first
126 name. It is only possible for in to appear as the first name in
127 the list, else it will be treated as marking the end of the
128 list.
129 for (( [expr1] ; [expr2] ; [expr3] )) do list done
131 The arithmetic expression expr1 is evaluated first (see the sec‐
132 tion `Arithmetic Evaluation'). The arithmetic expression expr2
133 is repeatedly evaluated until it evaluates to zero and when
134 non-zero, list is executed and the arithmetic expression expr3
135 evaluated. If any expression is omitted, then it behaves as if
136 it evaluated to 1.
137 while list do list done
139 Execute the do list as long as the while list returns a zero
140 exit status.
141 until list do list done
143 Execute the do list as long as until list returns a nonzero exit
144 status.
145 repeat word do list done
147 word is expanded and treated as an arithmetic expression, which
148 must evaluate to a number n. list is then executed n times.
149 case word in [ [(] pattern [ | pattern ] ... ) list (;;|;&) ] ... esac
151 Execute the list associated with the first pattern that matches
152 word, if any. The form of the patterns is the same as that used
153 for filename generation. See the section `Filename Generation'.
154 If the list that is executed is terminated with ;& rather than
155 ;;, the following list is also executed. This continues until
156 either a list is terminated with ;; or the esac is reached.
157 select name [ in word ... term ] do list done
159 where term is one or more newline or ; to terminate the words.
160 Print the set of words, each preceded by a number. If the in
161 word is omitted, use the positional parameters. The PROMPT3
162 prompt is printed and a line is read from the line editor if the
163 shell is interactive and that is active, or else standard input.
164 If this line consists of the number of one of the listed words,
165 then the parameter name is set to the word corresponding to this
166 number. If this line is empty, the selection list is printed
167 again. Otherwise, the value of the parameter name is set to
168 null. The contents of the line read from standard input is
169 saved in the parameter REPLY. list is executed for each selec‐
170 tion until a break or end-of-file is encountered.
171 ( list )
173 Execute list in a subshell. Traps set by the trap builtin are
174 reset to their default values while executing list.
175 { list }
177 Execute list.
178 { try-list } always { always-list }
180 First execute try-list. Regardless of errors, or break, con‐
181 tinue, or return commands encountered within try-list, execute
182 always-list. Execution then continues from the result of the
183 execution of try-list; in other words, any error, or break, con‐
184 tinue, or return command is treated in the normal way, as if
185 always-list were not present. The two chunks of code are
186 referred to as the `try block' and the `always block'.
187 Optional newlines or semicolons may appear after the always;
189 note, however, that they may not appear between the preceeding
190 closing brace and the always.
191 An `error' in this context is a condition such as a syntax error
193 which causes the shell to abort execution of the current func‐
194 tion, script, or list. Syntax errors encountered while the
195 shell is parsing the code do not cause the always-list to be
196 executed. For example, an erroneously constructed if block in
197 try-list would cause the shell to abort during parsing, so that
198 always-list would not be executed, while an erroneous substitu‐
199 tion such as ${*foo*} would cause a run-time error, after which
200 always-list would be executed.
201 An error condition can be tested and reset with the special
203 integer variable TRY_BLOCK_ERROR. Outside an always-list the
204 value is irrelevant, but it is initialised to -1. Inside
205 always-list, the value is 1 if an error occurred in the
206 try-list, else 0. If TRY_BLOCK_ERROR is set to 0 during the
207 always-list, the error condition caused by the try-list is
208 reset, and shell execution continues normally after the end of
209 always-list. Altering the value during the try-list is not use‐
210 ful (unless this forms part of an enclosing always block).
211 Regardless of TRY_BLOCK_ERROR, after the end of always-list the
213 normal shell status $? is the value returned from always-list.
214 This will be non-zero if there was an error, even if
215 TRY_BLOCK_ERROR was set to zero.
216 The following executes the given code, ignoring any errors it
218 causes. This is an alternative to the usual convention of pro‐
219 tecting code by executing it in a subshell.
220 {
222 # code which may cause an error
223 } always {
224 # This code is executed regardless of the error.
225 (( TRY_BLOCK_ERROR = 0 ))
226 }
227 # The error condition has been reset.
228 An exit command encountered in try-list does not cause the exe‐
230 cution of always-list. Instead, the shell exits immediately
231 after any EXIT trap has been executed.
232 function word ... [ () ] [ term ] { list }
234 word ... () [ term ] { list }
235 word ... () [ term ] command
236 where term is one or more newline or ;. Define a function which
237 is referenced by any one of word. Normally, only one word is
238 provided; multiple words are usually only useful for setting
239 traps. The body of the function is the list between the { and
240 }. See the section `Functions'.
241 If the option SH_GLOB is set for compatibility with other
243 shells, then whitespace may appear between between the left and
244 right parentheses when there is a single word; otherwise, the
245 parentheses will be treated as forming a globbing pattern in
246 that case.
247 time [ pipeline ]
249 The pipeline is executed, and timing statistics are reported on
250 the standard error in the form specified by the TIMEFMT parame‐
251 ter. If pipeline is omitted, print statistics about the shell
252 process and its children.
253 [[ exp ]]
255 Evaluates the conditional expression exp and return a zero exit
256 status if it is true. See the section `Conditional Expressions'
257 for a description of exp.
258
260 Many of zsh's complex commands have alternate forms. These particular
261 versions of complex commands should be considered deprecated and may be
262 removed in the future. The versions in the previous section should be
263 preferred instead.
264 The short versions below only work if sublist is of the form `{ list }'
266 or if the SHORT_LOOPS option is set. For the if, while and until com‐
267 mands, in both these cases the test part of the loop must also be suit‐
268 ably delimited, such as by `[[ ... ]]' or `(( ... ))', else the end of
269 the test will not be recognized. For the for, repeat, case and select
270 commands no such special form for the arguments is necessary, but the
271 other condition (the special form of sublist or use of the SHORT_LOOPS
272 option) still applies.
273 if list { list } [ elif list { list } ] ... [ else { list } ]
275 An alternate form of if. The rules mean that
276 if [[ -o ignorebraces ]] {
278 print yes
279 }
280 works, but
282 if true { # Does not work!
284 print yes
285 }
286 does not, since the test is not suitably delimited.
288 if list sublist
290 A short form of the alternate `if'. The same limitations on the
291 form of list apply as for the previous form.
292 for name ... ( word ... ) sublist
294 A short form of for.
295 for name ... [ in word ... ] term sublist
297 where term is at least one newline or ;. Another short form of
298 for.
299 for (( [expr1] ; [expr2] ; [expr3] )) sublist
301 A short form of the arithmetic for command.
302 foreach name ... ( word ... ) list end
304 Another form of for.
305 while list { list }
307 An alternative form of while. Note the limitations on the form
308 of list mentioned above.
309 until list { list }
311 An alternative form of until. Note the limitations on the form
312 of list mentioned above.
313 repeat word sublist
315 This is a short form of repeat.
316 case word { [ [(] pattern [ | pattern ] ... ) list (;;|;&) ] ... }
318 An alternative form of case.
319 select name [ in word term ] sublist
321 where term is at least one newline or ;. A short form of
322 select.
323
325 The following words are recognized as reserved words when used as the
326 first word of a command unless quoted or disabled using disable -r:
327 do done esac then elif else fi for case if while function repeat time
329 until select coproc nocorrect foreach end ! [[ { }
330 Additionally, `}' is recognized in any position if the IGNORE_BRACES
332 option is not set.
333
335 In noninteractive shells, or in interactive shells with the INTERAC‐
336 TIVE_COMMENTS option set, a word beginning with the third character of
337 the histchars parameter (`#' by default) causes that word and all the
338 following characters up to a newline to be ignored.
339
341 Every token in the shell input is checked to see if there is an alias
342 defined for it. If so, it is replaced by the text of the alias if it
343 is in command position (if it could be the first word of a simple com‐
344 mand), or if the alias is global. If the text ends with a space, the
345 next word in the shell input is treated as though it were in command
346 position for purposes of alias expansion. An alias is defined using
347 the alias builtin; global aliases may be defined using the -g option to
348 that builtin.
349 Alias expansion is done on the shell input before any other expansion
351 except history expansion. Therefore, if an alias is defined for the
352 word foo, alias expansion may be avoided by quoting part of the word,
353 e.g. \foo. But there is nothing to prevent an alias being defined for
354 \foo as well.
355
357 A character may be quoted (that is, made to stand for itself) by pre‐
358 ceding it with a `\'. `\' followed by a newline is ignored.
359 A string enclosed between `$'' and `'' is processed the same way as the
361 string arguments of the print builtin, and the resulting string is con‐
362 sidered to be entirely quoted. A literal `'' character can be included
363 in the string by using the `\'' escape.
364 All characters enclosed between a pair of single quotes ('') that is
366 not preceded by a `$' are quoted. A single quote cannot appear within
367 single quotes unless the option RC_QUOTES is set, in which case a pair
368 of single quotes are turned into a single quote. For example,
369 print ''''
371 outputs nothing apart from a newline if RC_QUOTES is not set, but one
373 single quote if it is set.
374 Inside double quotes (""), parameter and command substitution occur,
376 and `\' quotes the characters `\', ``', `"', and `$'.
377
379 If a command is followed by & and job control is not active, then the
380 default standard input for the command is the empty file /dev/null.
381 Otherwise, the environment for the execution of a command contains the
382 file descriptors of the invoking shell as modified by input/output
383 specifications.
384 The following may appear anywhere in a simple command or may precede or
386 follow a complex command. Expansion occurs before word or digit is
387 used except as noted below. If the result of substitution on word pro‐
388 duces more than one filename, redirection occurs for each separate
389 filename in turn.
390 < word Open file word for reading as standard input.
392 <> word
394 Open file word for reading and writing as standard input. If
395 the file does not exist then it is created.
396 > word Open file word for writing as standard output. If the file does
398 not exist then it is created. If the file exists, and the CLOB‐
399 BER option is unset, this causes an error; otherwise, it is
400 truncated to zero length.
401 >| word
403 >! word
404 Same as >, except that the file is truncated to zero length if
405 it exists, even if CLOBBER is unset.
406 >> word
408 Open file word for writing in append mode as standard output.
409 If the file does not exist, and the CLOBBER option is unset,
410 this causes an error; otherwise, the file is created.
411 >>| word
413 >>! word
414 Same as >>, except that the file is created if it does not
415 exist, even if CLOBBER is unset.
416 <<[-] word
418 The shell input is read up to a line that is the same as word,
419 or to an end-of-file. No parameter expansion, command substitu‐
420 tion or filename generation is performed on word. The resulting
421 document, called a here-document, becomes the standard input.
422 If any character of word is quoted with single or double quotes
424 or a `\', no interpretation is placed upon the characters of the
425 document. Otherwise, parameter and command substitution occurs,
426 `\' followed by a newline is removed, and `\' must be used to
427 quote the characters `\', `$', ``' and the first character of
428 word.
429 Note that word itself does not undergo shell expansion. Back‐
431 quotes in word do not have their usual effect; instead they
432 behave similarly to double quotes, except that the backquotes
433 themselves are passed through unchanged. (This information is
434 given for completeness and it is not recommended that backquotes
435 be used.) Quotes in the form $'...' have their standard effect
436 of expanding backslashed references to special characters.
437 If <<- is used, then all leading tabs are stripped from word and
439 from the document.
440 <<< word
442 Perform shell expansion on word and pass the result to standard
443 input. This is known as a here-string. Compare the use of word
444 in here-documents above, where word does not undergo shell
445 expansion.
446 <& number
448 >& number
449 The standard input/output is duplicated from file descriptor
450 number (see dup2(2)).
451 <& -
453 >& - Close the standard input/output.
454 <& p
456 >& p The input/output from/to the coprocess is moved to the standard
457 input/output.
458 >& word
460 &> word
461 (Except where `>& word' matches one of the above syntaxes; `&>'
462 can always be used to avoid this ambiguity.) Redirects both
463 standard output and standard error (file descriptor 2) in the
464 manner of `> word'. Note that this does not have the same
465 effect as `> word 2>&1' in the presence of multios (see the sec‐
466 tion below).
467 >&| word
469 >&! word
470 &>| word
471 &>! word
472 Redirects both standard output and standard error (file descrip‐
473 tor 2) in the manner of `>| word'.
474 >>& word
476 &>> word
477 Redirects both standard output and standard error (file descrip‐
478 tor 2) in the manner of `>> word'.
479 >>&| word
481 >>&! word
482 &>>| word
483 &>>! word
484 Redirects both standard output and standard error (file descrip‐
485 tor 2) in the manner of `>>| word'.
486 If one of the above is preceded by a digit, then the file descriptor
488 referred to is that specified by the digit instead of the default 0 or
489 1. The order in which redirections are specified is significant. The
490 shell evaluates each redirection in terms of the (file descriptor,
491 file) association at the time of evaluation. For example:
492 ... 1>fname 2>&1
494 first associates file descriptor 1 with file fname. It then associates
496 file descriptor 2 with the file associated with file descriptor 1 (that
497 is, fname). If the order of redirections were reversed, file descrip‐
498 tor 2 would be associated with the terminal (assuming file descriptor 1
499 had been) and then file descriptor 1 would be associated with file
500 fname.
501 The `|&' command separator described in Simple Commands & Pipelines in
503 zshmisc(1) is a shorthand for `2>&1 |'.
504 For output redirections only, if word is of the form `>(list)' then the
506 output is piped to the command represented by list. See Process Sub‐
507 stitution in zshexpn(1).
508
510 If the user tries to open a file descriptor for writing more than once,
511 the shell opens the file descriptor as a pipe to a process that copies
512 its input to all the specified outputs, similar to tee, provided the
513 MULTIOS option is set, as it is by default. Thus:
514 date >foo >bar
516 writes the date to two files, named `foo' and `bar'. Note that a pipe
518 is an implicit redirection; thus
519 date >foo | cat
521 writes the date to the file `foo', and also pipes it to cat.
523 If the MULTIOS option is set, the word after a redirection operator is
525 also subjected to filename generation (globbing). Thus
526 : > *
528 will truncate all files in the current directory, assuming there's at
530 least one. (Without the MULTIOS option, it would create an empty file
531 called `*'.) Similarly, you can do
532 echo exit 0 >> *.sh
534 If the user tries to open a file descriptor for reading more than once,
536 the shell opens the file descriptor as a pipe to a process that copies
537 all the specified inputs to its output in the order specified, similar
538 to cat, provided the MULTIOS option is set. Thus
539 sort <foo <fubar
541 or even
543 sort <f{oo,ubar}
545 is equivalent to `cat foo fubar | sort'.
547 Note that a pipe is an implicit redirection; thus
549 cat bar | sort <foo
551 is equivalent to `cat bar foo | sort' (note the order of the inputs).
553 If the MULTIOS option is unset, each redirection replaces the previous
555 redirection for that file descriptor. However, all files redirected to
556 are actually opened, so
557 echo foo > bar > baz
559 when MULTIOS is unset will truncate bar, and write `foo' into baz.
561 There is a problem when an output multio is attached to an external
563 program. A simple example shows this:
564 cat file >file1 >file2
566 cat file1 file2
567 Here, it is possible that the second `cat' will not display the full
569 contents of file1 and file2 (i.e. the original contents of file
570 repeated twice).
571 The reason for this is that the multios are spawned after the cat
573 process is forked from the parent shell, so the parent shell does not
574 wait for the multios to finish writing data. This means the command as
575 shown can exit before file1 and file2 are completely written. As a
576 workaround, it is possible to run the cat process as part of a job in
577 the current shell:
578 { cat file } >file >file2
580 Here, the {...} job will pause to wait for both files to be written.
582
584 When a simple command consists of one or more redirection operators and
585 zero or more parameter assignments, but no command name, zsh can behave
586 in several ways.
587 If the parameter NULLCMD is not set or the option CSH_NULLCMD is set,
589 an error is caused. This is the csh behavior and CSH_NULLCMD is set by
590 default when emulating csh.
591 If the option SH_NULLCMD is set, the builtin `:' is inserted as a com‐
593 mand with the given redirections. This is the default when emulating
594 sh or ksh.
595 Otherwise, if the parameter NULLCMD is set, its value will be used as a
597 command with the given redirections. If both NULLCMD and READNULLCMD
598 are set, then the value of the latter will be used instead of that of
599 the former when the redirection is an input. The default for NULLCMD
600 is `cat' and for READNULLCMD is `more'. Thus
601 < file
603 shows the contents of file on standard output, with paging if that is a
605 terminal. NULLCMD and READNULLCMD may refer to shell functions.
606
608 If a command name contains no slashes, the shell attempts to locate it.
609 If there exists a shell function by that name, the function is invoked
610 as described in the section `Functions'. If there exists a shell
611 builtin by that name, the builtin is invoked.
612 Otherwise, the shell searches each element of $path for a directory
614 containing an executable file by that name. If the search is unsuc‐
615 cessful, the shell prints an error message and returns a nonzero exit
616 status.
617 If execution fails because the file is not in executable format, and
619 the file is not a directory, it is assumed to be a shell script.
620 /bin/sh is spawned to execute it. If the program is a file beginning
621 with `#!', the remainder of the first line specifies an interpreter for
622 the program. The shell will execute the specified interpreter on oper‐
623 ating systems that do not handle this executable format in the kernel.
624
626 Shell functions are defined with the function reserved word or the spe‐
627 cial syntax `funcname ()'. Shell functions are read in and stored
628 internally. Alias names are resolved when the function is read. Func‐
629 tions are executed like commands with the arguments passed as posi‐
630 tional parameters. (See the section `Command Execution'.)
631 Functions execute in the same process as the caller and share all files
633 and present working directory with the caller. A trap on EXIT set
634 inside a function is executed after the function completes in the envi‐
635 ronment of the caller.
636 The return builtin is used to return from function calls.
638 Function identifiers can be listed with the functions builtin. Func‐
640 tions can be undefined with the unfunction builtin.
641
643 A function can be marked as undefined using the autoload builtin (or
644 `functions -u' or `typeset -fu'). Such a function has no body. When
645 the function is first executed, the shell searches for its definition
646 using the elements of the fpath variable. Thus to define functions for
647 autoloading, a typical sequence is:
648 fpath=(~/myfuncs $fpath)
650 autoload myfunc1 myfunc2 ...
651 The usual alias expansion during reading will be suppressed if the
653 autoload builtin or its equivalent is given the option -U. This is rec‐
654 ommended for the use of functions supplied with the zsh distribution.
655 Note that for functions precompiled with the zcompile builtin command
656 the flag -U must be provided when the .zwc file is created, as the cor‐
657 responding information is compiled into the latter.
658 For each element in fpath, the shell looks for three possible files,
660 the newest of which is used to load the definition for the function:
661 element.zwc
663 A file created with the zcompile builtin command, which is
664 expected to contain the definitions for all functions in the
665 directory named element. The file is treated in the same manner
666 as a directory containing files for functions and is searched
667 for the definition of the function. If the definition is not
668 found, the search for a definition proceeds with the other two
669 possibilities described below.
670 If element already includes a .zwc extension (i.e. the extension
672 was explicitly given by the user), element is searched for the
673 definition of the function without comparing its age to that of
674 other files; in fact, there does not need to be any directory
675 named element without the suffix. Thus including an element
676 such as `/usr/local/funcs.zwc' in fpath will speed up the search
677 for functions, with the disadvantage that functions included
678 must be explicitly recompiled by hand before the shell notices
679 any changes.
680 element/function.zwc
682 A file created with zcompile, which is expected to contain the
683 definition for function. It may include other function defini‐
684 tions as well, but those are neither loaded nor executed; a file
685 found in this way is searched only for the definition of func‐
686 tion.
687 element/function
689 A file of zsh command text, taken to be the definition for func‐
690 tion.
691 In summary, the order of searching is, first, in the parents of direc‐
693 tories in fpath for the newer of either a compiled directory or a
694 directory in fpath; second, if more than one of these contains a defi‐
695 nition for the function that is sought, the leftmost in the fpath is
696 chosen; and third, within a directory, the newer of either a compiled
697 function or an ordinary function definition is used.
698 If the KSH_AUTOLOAD option is set, or the file contains only a simple
700 definition of the function, the file's contents will be executed. This
701 will normally define the function in question, but may also perform
702 initialization, which is executed in the context of the function execu‐
703 tion, and may therefore define local parameters. It is an error if the
704 function is not defined by loading the file.
705 Otherwise, the function body (with no surrounding `funcname() {...}')
707 is taken to be the complete contents of the file. This form allows the
708 file to be used directly as an executable shell script. If processing
709 of the file results in the function being re-defined, the function
710 itself is not re-executed. To force the shell to perform initializa‐
711 tion and then call the function defined, the file should contain ini‐
712 tialization code (which will be executed then discarded) in addition to
713 a complete function definition (which will be retained for subsequent
714 calls to the function), and a call to the shell function, including any
715 arguments, at the end.
716 For example, suppose the autoload file func contains
718 func() { print This is func; }
720 print func is initialized
721 then `func; func' with KSH_AUTOLOAD set will produce both messages on
723 the first call, but only the message `This is func' on the second and
724 subsequent calls. Without KSH_AUTOLOAD set, it will produce the ini‐
725 tialization message on the first call, and the other message on the
726 second and subsequent calls.
727 It is also possible to create a function that is not marked as
729 autoloaded, but which loads its own definition by searching fpath, by
730 using `autoload -X' within a shell function. For example, the follow‐
731 ing are equivalent:
732 myfunc() {
734 autoload -X
735 }
736 myfunc args...
737 and
739 unfunction myfunc # if myfunc was defined
741 autoload myfunc
742 myfunc args...
743 In fact, the functions command outputs `builtin autoload -X' as the
745 body of an autoloaded function. This is done so that
746 eval "$(functions)"
748 produces a reasonable result. A true autoloaded function can be iden‐
750 tified by the presence of the comment `# undefined' in the body,
751 because all comments are discarded from defined functions.
752 To load the definition of an autoloaded function myfunc without execut‐
754 ing myfunc, use:
755 autoload +X myfunc
757
759 The following functions, if defined, have special meaning to the shell:
760 chpwd Executed whenever the current working directory is changed.
762 periodic
764 If the parameter PERIOD is set, this function is executed every
765 $PERIOD seconds, just before a prompt.
766 precmd Executed before each prompt.
768 preexec
770 Executed just after a command has been read and is about to be
771 executed. If the history mechanism is active (and the line was
772 not discarded from the history buffer), the string that the user
773 typed is passed as the first argument, otherwise it is an empty
774 string. The actual command that will be executed (including
775 expanded aliases) is passed in two different forms: the second
776 argument is a single-line, size-limited version of the command
777 (with things like function bodies elided); the third argument
778 contains the full text that is being executed.
779 TRAPNAL
781 If defined and non-null, this function will be executed whenever
782 the shell catches a signal SIGNAL, where NAL is a signal name as
783 specified for the kill builtin. The signal number will be
784 passed as the first parameter to the function.
785 If a function of this form is defined and null, the shell and
787 processes spawned by it will ignore SIGNAL.
788 The return value from the function is handled specially. If it
790 is zero, the signal is assumed to have been handled, and execu‐
791 tion continues normally. Otherwise, the normal effect of the
792 signal is produced; if this causes execution to terminate, the
793 status returned to the shell is the status returned from the
794 function.
795 Programs terminated by uncaught signals typically return the
797 status 128 plus the signal number. Hence the following causes
798 the handler for SIGINT to print a message, then mimic the usual
799 effect of the signal.
800 TRAPINT() {
802 print "Caught SIGINT, aborting."
803 return $(( 128 + $1 ))
804 }
805 The functions TRAPZERR, TRAPDEBUG and TRAPEXIT are never exe‐
807 cuted inside other traps.
808 TRAPDEBUG
810 Executed after each command.
811 TRAPEXIT
813 Executed when the shell exits, or when the current function
814 exits if defined inside a function.
815 TRAPZERR
817 Executed whenever a command has a non-zero exit status. How‐
818 ever, the function is not executed if the command occurred in a
819 sublist followed by `&&' or `||'; only the final command in a
820 sublist of this type causes the trap to be executed.
821 The functions beginning `TRAP' may alternatively be defined with the
823 trap builtin: this may be preferable for some uses, as they are then
824 run in the environment of the calling process, rather than in their own
825 function environment. Apart from the difference in calling procedure
826 and the fact that the function form appears in lists of functions, the
827 forms
828 TRAPNAL() {
830 # code
831 }
832 and
834 trap '
836 # code
837 are equivalent.
839
841 If the MONITOR option is set, an interactive shell associates a job
842 with each pipeline. It keeps a table of current jobs, printed by the
843 jobs command, and assigns them small integer numbers. When a job is
844 started asynchronously with `&', the shell prints a line to standard
845 error which looks like:
846 [1] 1234
848 indicating that the job which was started asynchronously was job number
850 1 and had one (top-level) process, whose process ID was 1234.
851 If a job is started with `&|' or `&!', then that job is immediately
853 disowned. After startup, it does not have a place in the job table,
854 and is not subject to the job control features described here.
855 If you are running a job and wish to do something else you may hit the
857 key ^Z (control-Z) which sends a TSTP signal to the current job: this
858 key may be redefined by the susp option of the external stty command.
859 The shell will then normally indicate that the job has been `sus‐
860 pended', and print another prompt. You can then manipulate the state
861 of this job, putting it in the background with the bg command, or run
862 some other commands and then eventually bring the job back into the
863 foreground with the foreground command fg. A ^Z takes effect immedi‐
864 ately and is like an interrupt in that pending output and unread input
865 are discarded when it is typed.
866 A job being run in the background will suspend if it tries to read from
868 the terminal. Background jobs are normally allowed to produce output,
869 but this can be disabled by giving the command `stty tostop'. If you
870 set this tty option, then background jobs will suspend when they try to
871 produce output like they do when they try to read input.
872 When a command is suspended and continued later with the fg or wait
874 builtins, zsh restores tty modes that were in effect when it was sus‐
875 pended. This (intentionally) does not apply if the command is contin‐
876 ued via `kill -CONT', nor when it is continued with bg.
877 There are several ways to refer to jobs in the shell. A job can be
879 referred to by the process ID of any process of the job or by one of
880 the following:
881 %number
883 The job with the given number.
884 %string
885 Any job whose command line begins with string.
886 %?string
887 Any job whose command line contains string.
888 %% Current job.
889 %+ Equivalent to `%%'.
890 %- Previous job.
891 The shell learns immediately whenever a process changes state. It nor‐
893 mally informs you whenever a job becomes blocked so that no further
894 progress is possible. If the NOTIFY option is not set, it waits until
895 just before it prints a prompt before it informs you. All such notifi‐
896 cations are sent directly to the terminal, not to the standard output
897 or standard error.
898 When the monitor mode is on, each background job that completes trig‐
900 gers any trap set for CHLD.
901 When you try to leave the shell while jobs are running or suspended,
903 you will be warned that `You have suspended (running) jobs'. You may
904 use the jobs command to see what they are. If you do this or immedi‐
905 ately try to exit again, the shell will not warn you a second time; the
906 suspended jobs will be terminated, and the running jobs will be sent a
907 SIGHUP signal, if the HUP option is set.
908 To avoid having the shell terminate the running jobs, either use the
910 nohup command (see nohup(1)) or the disown builtin.
911
913 The INT and QUIT signals for an invoked command are ignored if the com‐
914 mand is followed by `&' and the MONITOR option is not active. Other‐
915 wise, signals have the values inherited by the shell from its parent
916 (but see the TRAPNAL special functions in the section `Functions').
917
919 The shell can perform integer and floating point arithmetic, either
920 using the builtin let, or via a substitution of the form $((...)). For
921 integers, the shell is usually compiled to use 8-byte precision where
922 this is available, otherwise precision is 4 bytes. This can be tested,
923 for example, by giving the command `print - $(( 12345678901 ))'; if the
924 number appears unchanged, the precision is at least 8 bytes. Floating
925 point arithmetic is always double precision.
926 The let builtin command takes arithmetic expressions as arguments; each
928 is evaluated separately. Since many of the arithmetic operators, as
929 well as spaces, require quoting, an alternative form is provided: for
930 any command which begins with a `((', all the characters until a match‐
931 ing `))' are treated as a quoted expression and arithmetic expansion
932 performed as for an argument of let. More precisely, `((...))' is
933 equivalent to `let "..."'. For example, the following statement
934 (( val = 2 + 1 ))
936 is equivalent to
938 let "val = 2 + 1"
940 both assigning the value 3 to the shell variable val and returning a
942 zero status.
943 Integers can be in bases other than 10. A leading `0x' or `0X' denotes
945 hexadecimal. Integers may also be of the form `base#n', where base is
946 a decimal number between two and thirty-six representing the arithmetic
947 base and n is a number in that base (for example, `16#ff' is 255 in
948 hexadecimal). The base# may also be omitted, in which case base 10 is
949 used. For backwards compatibility the form `[base]n' is also accepted.
950 It is also possible to specify a base to be used for output in the form
952 `[#base]', for example `[#16]'. This is used when outputting arith‐
953 metical substitutions or when assigning to scalar parameters, but an
954 explicitly defined integer or floating point parameter will not be
955 affected. If an integer variable is implicitly defined by an arith‐
956 metic expression, any base specified in this way will be set as the
957 variable's output arithmetic base as if the option `-i base' to the
958 typeset builtin had been used. The expression has no precedence and if
959 it occurs more than once in a mathematical expression, the last encoun‐
960 tered is used. For clarity it is recommended that it appear at the
961 beginning of an expression. As an example:
962 typeset -i 16 y
964 print $(( [#8] x = 32, y = 32 ))
965 print $x $y
966 outputs first `8#40', the rightmost value in the given output base, and
968 then `8#40 16#20', because y has been explicitly declared to have out‐
969 put base 16, while x (assuming it does not already exist) is implicitly
970 typed by the arithmetic evaluation, where it acquires the output base
971 8.
972 If the C_BASES option is set, hexadecimal numbers in the standard C
974 format, for example 0xFF instead of the usual `16#FF'. If the option
975 OCTAL_ZEROES is also set (it is not by default), octal numbers will be
976 treated similarly and hence appear as `077' instead of `8#77'. This
977 option has no effect on the output of bases other than hexadecimal and
978 octal, and these formats are always understood on input.
979 When an output base is specified using the `[#base]' syntax, an appro‐
981 priate base prefix will be output if necessary, so that the value out‐
982 put is valid syntax for input. If the # is doubled, for example
983 `[##16]', then no base prefix is output.
984 Floating point constants are recognized by the presence of a decimal
986 point or an exponent. The decimal point may be the first character of
987 the constant, but the exponent character e or E may not, as it will be
988 taken for a parameter name.
989 An arithmetic expression uses nearly the same syntax, precedence, and
991 associativity of expressions in C. The following operators are sup‐
992 ported (listed in decreasing order of precedence):
993 + - ! ~ ++ --
995 unary plus/minus, logical NOT, complement, {pre,post}{in,de}cre‐
996 ment
997 << >> bitwise shift left, right
998 & bitwise AND
999 ^ bitwise XOR
1000 | bitwise OR
1001 ** exponentiation
1002 * / % multiplication, division, modulus (remainder)
1003 + - addition, subtraction
1004 < > <= >=
1005 comparison
1006 == != equality and inequality
1007 && logical AND
1008 || ^^ logical OR, XOR
1009 ? : ternary operator
1010 = += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=
1011 assignment
1012 , comma operator
1013 The operators `&&', `||', `&&=', and `||=' are short-circuiting, and
1015 only one of the latter two expressions in a ternary operator is evalu‐
1016 ated. Note the precedence of the bitwise AND, OR, and XOR operators.
1017 Mathematical functions can be called with the syntax `func(args)',
1019 where the function decides if the args is used as a string or a
1020 comma-separated list of arithmetic expressions. The shell currently
1021 defines no mathematical functions by default, but the module zsh/math‐
1022 func may be loaded with the zmodload builtin to provide standard float‐
1023 ing point mathematical functions.
1024 An expression of the form `##x' where x is any character sequence such
1026 as `a', `^A', or `\M-\C-x' gives the ASCII value of this character and
1027 an expression of the form `#foo' gives the ASCII value of the first
1028 character of the value of the parameter foo. Note that this is differ‐
1029 ent from the expression `$#foo', a standard parameter substitution
1030 which gives the length of the parameter foo. `#\' is accepted instead
1031 of `##', but its use is deprecated.
1032 Named parameters and subscripted arrays can be referenced by name
1034 within an arithmetic expression without using the parameter expansion
1035 syntax. For example,
1036 ((val2 = val1 * 2))
1038 assigns twice the value of $val1 to the parameter named val2.
1040 An internal integer representation of a named parameter can be speci‐
1042 fied with the integer builtin. Arithmetic evaluation is performed on
1043 the value of each assignment to a named parameter declared integer in
1044 this manner. Assigning a floating point number to an integer results
1045 in rounding down to the next integer.
1046 Likewise, floating point numbers can be declared with the float
1048 builtin; there are two types, differing only in their output format, as
1049 described for the typeset builtin. The output format can be bypassed
1050 by using arithmetic substitution instead of the parameter substitution,
1051 i.e. `${float}' uses the defined format, but `$((float))' uses a
1052 generic floating point format.
1053 Promotion of integer to floating point values is performed where neces‐
1055 sary. In addition, if any operator which requires an integer (`~',
1056 `&', `|', `^', `%', `<<', `>>' and their equivalents with assignment)
1057 is given a floating point argument, it will be silently rounded down to
1058 the next integer.
1059 Scalar variables can hold integer or floating point values at different
1061 times; there is no memory of the numeric type in this case.
1062 If a variable is first assigned in a numeric context without previously
1064 being declared, it will be implicitly typed as integer or float and
1065 retain that type either until the type is explicitly changed or until
1066 the end of the scope. This can have unforeseen consequences. For
1067 example, in the loop
1068 for (( f = 0; f < 1; f += 0.1 )); do
1070 # use $f
1071 done
1072 if f has not already been declared, the first assignment will cause it
1074 to be created as an integer, and consequently the operation `f += 0.1'
1075 will always cause the result to be truncated to zero, so that the loop
1076 will fail. A simple fix would be to turn the initialization into `f =
1077 0.0'. It is therefore best to declare numeric variables with explicit
1078 types.
1079
1081 A conditional expression is used with the [[ compound command to test
1082 attributes of files and to compare strings. Each expression can be
1083 constructed from one or more of the following unary or binary expres‐
1084 sions:
1085 -a file
1087 true if file exists.
1088 -b file
1090 true if file exists and is a block special file.
1091 -c file
1093 true if file exists and is a character special file.
1094 -d file
1096 true if file exists and is a directory.
1097 -e file
1099 true if file exists.
1100 -f file
1102 true if file exists and is a regular file.
1103 -g file
1105 true if file exists and has its setgid bit set.
1106 -h file
1108 true if file exists and is a symbolic link.
1109 -k file
1111 true if file exists and has its sticky bit set.
1112 -n string
1114 true if length of string is non-zero.
1115 -o option
1117 true if option named option is on. option may be a single char‐
1118 acter, in which case it is a single letter option name. (See
1119 the section `Specifying Options'.)
1120 -p file
1122 true if file exists and is a FIFO special file (named pipe).
1123 -r file
1125 true if file exists and is readable by current process.
1126 -s file
1128 true if file exists and has size greater than zero.
1129 -t fd true if file descriptor number fd is open and associated with a
1131 terminal device. (note: fd is not optional)
1132 -u file
1134 true if file exists and has its setuid bit set.
1135 -w file
1137 true if file exists and is writable by current process.
1138 -x file
1140 true if file exists and is executable by current process. If
1141 file exists and is a directory, then the current process has
1142 permission to search in the directory.
1143 -z string
1145 true if length of string is zero.
1146 -L file
1148 true if file exists and is a symbolic link.
1149 -O file
1151 true if file exists and is owned by the effective user ID of
1152 this process.
1153 -G file
1155 true if file exists and its group matches the effective group ID
1156 of this process.
1157 -S file
1159 true if file exists and is a socket.
1160 -N file
1162 true if file exists and its access time is not newer than its
1163 modification time.
1164 file1 -nt file2
1166 true if file1 exists and is newer than file2.
1167 file1 -ot file2
1169 true if file1 exists and is older than file2.
1170 file1 -ef file2
1172 true if file1 and file2 exist and refer to the same file.
1173 string = pattern
1175 string == pattern
1176 true if string matches pattern. The `==' form is the preferred
1177 one. The `=' form is for backward compatibility and should be
1178 considered obsolete.
1179 string != pattern
1181 true if string does not match pattern.
1182 string1 < string2
1184 true if string1 comes before string2 based on ASCII value of
1185 their characters.
1186 string1 > string2
1188 true if string1 comes after string2 based on ASCII value of
1189 their characters.
1190 exp1 -eq exp2
1192 true if exp1 is numerically equal to exp2.
1193 exp1 -ne exp2
1195 true if exp1 is numerically not equal to exp2.
1196 exp1 -lt exp2
1198 true if exp1 is numerically less than exp2.
1199 exp1 -gt exp2
1201 true if exp1 is numerically greater than exp2.
1202 exp1 -le exp2
1204 true if exp1 is numerically less than or equal to exp2.
1205 exp1 -ge exp2
1207 true if exp1 is numerically greater than or equal to exp2.
1208 ( exp )
1210 true if exp is true.
1211 ! exp true if exp is false.
1213 exp1 && exp2
1215 true if exp1 and exp2 are both true.
1216 exp1 || exp2
1218 true if either exp1 or exp2 is true.
1219 Normal shell expansion is performed on the file, string and pattern
1221 arguments, but the result of each expansion is constrained to be a sin‐
1222 gle word, similar to the effect of double quotes. However, pattern
1223 metacharacters are active for the pattern arguments; the patterns are
1224 the same as those used for filename generation, see zshexpn(1), but
1225 there is no special behaviour of `/' nor initial dots, and no glob
1226 qualifiers are allowed.
1227 In each of the above expressions, if file is of the form `/dev/fd/n',
1229 where n is an integer, then the test applied to the open file whose
1230 descriptor number is n, even if the underlying system does not support
1231 the /dev/fd directory.
1232 In the forms which do numeric comparison, the expressions exp undergo
1234 arithmetic expansion as if they were enclosed in $((...)).
1235 For example, the following:
1237 [[ ( -f foo || -f bar ) && $report = y* ]] && print File exists.
1239 tests if either file foo or file bar exists, and if so, if the value of
1241 the parameter report begins with `y'; if the complete condition is
1242 true, the message `File exists.' is printed.
1243
1245 Prompt sequences undergo a special form of expansion. This type of
1246 expansion is also available using the -P option to the print builtin.
1247 If the PROMPT_SUBST option is set, the prompt string is first subjected
1249 to parameter expansion, command substitution and arithmetic expansion.
1250 See zshexpn(1).
1251 Certain escape sequences may be recognised in the prompt string.
1253 If the PROMPT_BANG option is set, a `!' in the prompt is replaced by
1255 the current history event number. A literal `!' may then be repre‐
1256 sented as `!!'.
1257 If the PROMPT_PERCENT option is set, certain escape sequences that
1259 start with `%' are expanded. Some escapes take an optional integer
1260 argument, which should appear between the `%' and the next character of
1261 the sequence. The following escape sequences are recognized:
1262 Special characters
1264 %% A `%'.
1265 %) A `)'.
1267 Login information
1269 %l The line (tty) the user is logged in on, without `/dev/' prefix.
1270 If the name starts with `/dev/tty', that prefix is stripped.
1271 %M The full machine hostname.
1273 %m The hostname up to the first `.'. An integer may follow the `%'
1275 to specify how many components of the hostname are desired.
1276 With a negative integer, trailing components of the hostname are
1277 shown.
1278 %n $USERNAME.
1280 %y The line (tty) the user is logged in on, without `/dev/' prefix.
1282 This does not treat `/dev/tty' names specially.
1283 Shell state
1285 %# A `#' if the shell is running with privileges, a `%' if not.
1286 Equivalent to `%(!.#.%%)'. The definition of `privileged', for
1287 these purposes, is that either the effective user ID is zero,
1288 or, if POSIX.1e capabilities are supported, that at least one
1289 capability is raised in either the Effective or Inheritable
1290 capability vectors.
1291 %? The return code of the last command executed just before the
1293 prompt.
1294 %_ The status of the parser, i.e. the shell constructs (like `if'
1296 and `for') that have been started on the command line. If given
1297 an integer number that many strings will be printed; zero or
1298 negative or no integer means print as many as there are. This
1299 is most useful in prompts PS2 for continuation lines and PS4 for
1300 debugging with the XTRACE option; in the latter case it will
1301 also work non-interactively.
1302 %d
1304 %/ Present working directory ($PWD). If an integer follows the
1305 `%', it specifies a number of trailing components of $PWD to
1306 show; zero means the whole path. A negative integer specifies
1307 leading components, i.e. %-1d specifies the first component.
1308 %~ As %d and %/, but if $PWD has a named directory as its prefix,
1310 that part is replaced by a `~' followed by the name of the
1311 directory. If it starts with $HOME, that part is replaced by a
1312 `~'.
1313 %h
1315 %! Current history event number.
1316 %i The line number currently being executed in the script, sourced
1318 file, or shell function given by %N. This is most useful for
1319 debugging as part of $PS4.
1320 %j The number of jobs.
1322 %L The current value of $SHLVL.
1324 %N The name of the script, sourced file, or shell function that zsh
1326 is currently executing, whichever was started most recently. If
1327 there is none, this is equivalent to the parameter $0. An inte‐
1328 ger may follow the `%' to specify a number of trailing path com‐
1329 ponents to show; zero means the full path. A negative integer
1330 specifies leading components.
1331 %c
1333 %.
1334 %C Trailing component of $PWD. An integer may follow the `%' to
1335 get more than one component. Unless `%C' is used, tilde con‐
1336 traction is performed first. These are deprecated as %c and %C
1337 are equivalent to %1~ and %1/, respectively, while explicit pos‐
1338 itive integers have the same effect as for the latter two
1339 sequences.
1340 Date and time
1342 %D The date in yy-mm-dd format.
1343 %T Current time of day, in 24-hour format.
1345 %t
1347 %@ Current time of day, in 12-hour, am/pm format.
1348 %* Current time of day in 24-hour format, with seconds.
1350 %w The date in day-dd format.
1352 %W The date in mm/dd/yy format.
1354 %D{string}
1356 string is formatted using the strftime function. See strf‐
1357 time(3) for more details. Three additional codes are available:
1358 %f prints the day of the month, like %e but without any preced‐
1359 ing space if the day is a single digit, and %K/%L correspond to
1360 %k/%l for the hour of the day (24/12 hour clock) in the same
1361 way.
1362 Visual effects
1364 %B (%b)
1365 Start (stop) boldface mode.
1366 %E Clear to end of line.
1368 %U (%u)
1370 Start (stop) underline mode.
1371 %S (%s)
1373 Start (stop) standout mode.
1374 %{...%}
1376 Include a string as a literal escape sequence. The string
1377 within the braces should not change the cursor position. Brace
1378 pairs can nest.
1379 Conditional substrings
1381 %v The value of the first element of the psvar array parameter.
1382 Following the `%' with an integer gives that element of the
1383 array. Negative integers count from the end of the array.
1384 %(x.true-text.false-text)
1386 Specifies a ternary expression. The character following the x
1387 is arbitrary; the same character is used to separate the text
1388 for the `true' result from that for the `false' result. This
1389 separator may not appear in the true-text, except as part of a
1390 %-escape sequence. A `)' may appear in the false-text as `%)'.
1391 true-text and false-text may both contain arbitrarily-nested
1392 escape sequences, including further ternary expressions.
1393 The left parenthesis may be preceded or followed by a positive
1395 integer n, which defaults to zero. A negative integer will be
1396 multiplied by -1. The test character x may be any of the fol‐
1397 lowing:
1398 ! True if the shell is running with privileges.
1400 # True if the effective uid of the current process is n.
1401 ? True if the exit status of the last command was n.
1402 _ True if at least n shell constructs were started.
1403 C
1404 / True if the current absolute path has at least n elements
1405 relative to the root directory, hence / is counted as 0
1406 elements.
1407 c
1408 .
1409 ~ True if the current path, with prefix replacement, has at
1410 least n elements relative to the root directory, hence /
1411 is counted as 0 elements.
1412 D True if the month is equal to n (January = 0).
1413 d True if the day of the month is equal to n.
1414 g True if the effective gid of the current process is n.
1415 j True if the number of jobs is at least n.
1416 L True if the SHLVL parameter is at least n.
1417 l True if at least n characters have already been printed
1418 on the current line.
1419 S True if the SECONDS parameter is at least n.
1420 T True if the time in hours is equal to n.
1421 t True if the time in minutes is equal to n.
1422 v True if the array psvar has at least n elements.
1423 w True if the day of the week is equal to n (Sunday = 0).
1424 %<string<
1426 %>string>
1427 %[xstring]
1428 Specifies truncation behaviour for the remainder of the prompt
1429 string. The third, deprecated, form is equivalent to
1430 `%xstringx', i.e. x may be `<' or `>'. The numeric argument,
1431 which in the third form may appear immediately after the `[',
1432 specifies the maximum permitted length of the various strings
1433 that can be displayed in the prompt. The string will be dis‐
1434 played in place of the truncated portion of any string; note
1435 this does not undergo prompt expansion.
1436 The forms with `<' truncate at the left of the string, and the
1438 forms with `>' truncate at the right of the string. For exam‐
1439 ple, if the current directory is `/home/pike', the prompt
1440 `%8<..<%/' will expand to `..e/pike'. In this string, the ter‐
1441 minating character (`<', `>' or `]'), or in fact any character,
1442 may be quoted by a preceding `\'; note when using print -P, how‐
1443 ever, that this must be doubled as the string is also subject to
1444 standard print processing, in addition to any backslashes
1445 removed by a double quoted string: the worst case is therefore
1446 `print -P "%<\\\\<<..."'.
1447 If the string is longer than the specified truncation length, it
1449 will appear in full, completely replacing the truncated string.
1450 The part of the prompt string to be truncated runs to the end of
1452 the string, or to the end of the next enclosing group of the
1453 `%(' construct, or to the next truncation encountered at the
1454 same grouping level (i.e. truncations inside a `%(' are sepa‐
1455 rate), which ever comes first. In particular, a truncation with
1456 argument zero (e.g. `%<<') marks the end of the range of the
1457 string to be truncated while turning off truncation from there
1458 on. For example, the prompt '%10<...<%~%<<%# ' will print a
1459 truncated representation of the current directory, followed by a
1460 `%' or `#', followed by a space. Without the `%<<', those two
1461 characters would be included in the string to be truncated.
1462zsh 4.2.6 November 28, 2005 ZSHMISC(1)