1KSH(1) General Commands Manual KSH(1)
2
6 ksh, rksh, pfksh - KornShell, a standard/restricted command and pro‐
7 gramming language
8
10 Currently, rksh and pfksh are not available on macOS / Darwin.
11
13 ksh [ ±abcefhiknoprstuvxBCDP ] [ -R file ] [ ±o option ] ... [ - ] [
14 arg ... ]
15
17 Ksh is a command and programming language that executes commands read
18 from a terminal or a file. Rksh is a restricted version of the command
19 interpreter ksh; it is used to set up login names and execution envi‐
20 ronments whose capabilities are more controlled than those of the stan‐
21 dard shell. Rpfksh is a profile shell version of the command inter‐
22 preter ksh; it is used to execute commands with the attributes speci‐
23 fied by the user's profiles (see pfexec(1)). See Invocation below for
24 the meaning of arguments to the shell.
25 Definitions.
27 A metacharacter is one of the following characters:
28 ; & ( ) ⎪ < > new-line space tab
30 A blank is a tab or a space. An identifier is a sequence of letters,
32 digits, or underscores starting with a letter or underscore. Identi‐
33 fiers are used as components of variable names. A vname is a sequence
34 of one or more identifiers separated by a . and optionally preceded by
35 a .. Vnames are used as function and variable names. A word is a
36 sequence of characters from the character set defined by the current
37 locale, excluding non-quoted metacharacters.
38 A command is a sequence of characters in the syntax of the shell lan‐
40 guage. The shell reads each command and carries out the desired action
41 either directly or by invoking separate utilities. A built-in command
42 is a command that is carried out by the shell itself without creating a
43 separate process. Some commands are built-in purely for convenience
44 and are not documented here. Built-ins that cause side effects in the
45 shell environment and built-ins that are found before performing a path
46 search (see Execution below) are documented here. For historical rea‐
47 sons, some of these built-ins behave differently than other built-ins
48 and are called special built-ins.
49 Commands.
51 A simple-command is a list of variable assignments (see Variable
52 Assignments below) or a sequence of blank separated words which may be
53 preceded by a list of variable assignments (see Environment below).
54 The first word specifies the name of the command to be executed.
55 Except as specified below, the remaining words are passed as arguments
56 to the invoked command. The command name is passed as argument 0 (see
57 exec(2)). The value of a simple-command is its exit status; 0-255 if
58 it terminates normally; 256+signum if it terminates abnormally (the
59 name of the signal corresponding to the exit status can be obtained via
60 the -l option of the kill built-in utility).
61 A pipeline is a sequence of one or more commands separated by ⎪. The
63 standard output of each command but the last is connected by a pipe(2)
64 to the standard input of the next command. Each command, except possi‐
65 bly the last, is run as a separate process; the shell waits for the
66 last command to terminate. The exit status of a pipeline is the exit
67 status of the last command unless the pipefail option is enabled. Each
68 pipeline can be preceded by the reserved word ! which causes the exit
69 status of the pipeline to become 0 if the exit status of the last com‐
70 mand is non-zero, and 1 if the exit status of the last command is 0.
71 A list is a sequence of one or more pipelines separated by ;, &, ⎪&,
73 &&, or ⎪⎪, and optionally terminated by ;, &, or ⎪&. Of these five
74 symbols, ;, &, and ⎪& have equal precedence, which is lower than that
75 of && and ⎪⎪. The symbols && and ⎪⎪ also have equal precedence. A
76 semicolon (;) causes sequential execution of the preceding pipeline; an
77 ampersand (&) causes asynchronous execution of the preceding pipeline
78 (i.e., the shell does not wait for that pipeline to finish). The sym‐
79 bol ⎪& causes asynchronous execution of the preceding pipeline with a
80 two-way pipe established to the parent shell; the standard input and
81 output of the spawned pipeline can be written to and read from by the
82 parent shell by applying the redirection operators <& and >& with arg p
83 to commands and by using -p option of the built-in commands read and
84 print described later. The symbol && (⎪⎪) causes the list following it
85 to be executed only if the preceding pipeline returns a zero (non-zero)
86 value. One or more new-lines may appear in a list instead of a semi‐
87 colon, to delimit a command. The first item of the first pipeline of
88 a list that is a simple command not beginning with a redirection, and
89 not occurring within a while, until, or if list, can be preceded by a
90 semicolon. This semicolon is ignored unless the showme option is
91 enabled as described with the set built-in below.
92 A command is either a simple-command or one of the following. Unless
94 otherwise stated, the value returned by a command is that of the last
95 simple-command executed in the command.
96 for vname [ in word ... ] ;do list ;done
98 Each time a for command is executed, vname is set to the next
99 word taken from the in word list. If in word ... is omitted,
100 then the for command executes the do list once for each posi‐
101 tional parameter that is set starting from 1 (see Parameter
102 Expansion below). Execution ends when there are no more words
103 in the list.
104 for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
106 The arithmetic expression expr1 is evaluated first (see Arith‐
107 metic evaluation below). The arithmetic expression expr2 is
108 repeatedly evaluated until it evaluates to zero and when non-
109 zero, list is executed and the arithmetic expression expr3 eval‐
110 uated. If any expression is omitted, then it behaves as if it
111 evaluated to 1.
112 select vname [ in word ... ] ;do list ;done
114 A select command prints on standard error (file descriptor 2)
115 the set of words, each preceded by a number. If in word ... is
116 omitted, then the positional parameters starting from 1 are used
117 instead (see Parameter Expansion below). The PS3 prompt is
118 printed and a line is read from the standard input. If this
119 line consists of the number of one of the listed words, then the
120 value of the variable vname is set to the word corresponding to
121 this number. If this line is empty, the selection list is
122 printed again. Otherwise the value of the variable vname is set
123 to null. The contents of the line read from standard input is
124 saved in the variable REPLY. The list is executed for each
125 selection until a break or end-of-file is encountered. If the
126 REPLY variable is set to null by the execution of list, then the
127 selection list is printed before displaying the PS3 prompt for
128 the next selection.
129 case word in [ [(]pattern [ ⎪ pattern ] ... ) list ;; ] ... esac
131 A case command executes the list associated with the first pat‐
132 tern that matches word. The form of the patterns is the same as
133 that used for file-name generation (see File Name Generation
134 below). The ;; operator causes execution of case to terminate.
135 If ;& is used in place of ;; the next subsequent list, if any,
136 is executed.
137 if list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi
139 The list following if is executed and, if it returns a zero exit
140 status, the list following the first then is executed. Other‐
141 wise, the list following elif is executed and, if its value is
142 zero, the list following the next then is executed. Failing
143 each successive elif list, the else list is executed. If the if
144 list has non-zero exit status and there is no else list, then
145 the if command returns a zero exit status.
146 while list ;do list ;done
148 until list ;do list ;done
149 A while command repeatedly executes the while list and, if the
150 exit status of the last command in the list is zero, executes
151 the do list; otherwise the loop terminates. If no commands in
152 the do list are executed, then the while command returns a zero
153 exit status; until may be used in place of while to negate the
154 loop termination test.
155 ((expression))
157 The expression is evaluated using the rules for arithmetic eval‐
158 uation described below. If the value of the arithmetic expres‐
159 sion is non-zero, the exit status is 0, otherwise the exit sta‐
160 tus is 1.
161 (list)
163 Execute list in a separate environment. Note, that if two adja‐
164 cent open parentheses are needed for nesting, a space must be
165 inserted to avoid evaluation as an arithmetic command as
166 described above.
167 { list;}
169 list is simply executed. Note that unlike the metacharacters (
170 and ), { and } are reserved words and must occur at the begin‐
171 ning of a line or after a ; in order to be recognized.
172 [[ expression ]]
174 Evaluates expression and returns a zero exit status when expres‐
175 sion is true. See Conditional Expressions below, for a descrip‐
176 tion of expression.
177 function varname { list ;}
179 varname () { list ;}
180 Define a function which is referenced by varname. A function
181 whose varname contains a . is called a discipline function and
182 the portion of the varname preceding the last . must refer to
183 an existing variable. The body of the function is the list of
184 commands between { and }. A function defined with the function
185 varname syntax can also be used as an argument to the . special
186 built-in command to get the equivalent behavior as if the var‐
187 name() syntax were used to define it. (See Functions below.)
188 namespace varname { list ;}
190 Defines or uses the name space identifier and runs the commands
191 in list in this name space. (See Name Spaces below.)
192 & [ name [ arg... ] ]
194 Causes subsequent list commands terminated by & to be placed in
195 the background job pool name. If name is omitted a default
196 unnamed pool is used. Commands in a named background pool may
197 be executed remotely.
198 time [ pipeline ]
200 If pipeline is omitted the user and system time for the current
201 shell and completed child processes is printed on standard
202 error. Otherwise, pipeline is executed and the elapsed time as
203 well as the user and system time are printed on standard error.
204 The TIMEFORMAT variable may be set to a format string that spec‐
205 ifies how the timing information should be displayed. See Shell
206 Variables below for a description of the TIMEFORMAT variable.
207 The following reserved words are recognized as reserved only when they
209 are the first word of a command and are not quoted:
210 if then else elif fi case esac for while until do done { } function
212 select time [[ ]] !
213 Variable Assignments.
215 One or more variable assignments can start a simple command or can be
216 arguments to the typeset, enum, export, or readonly special built-in
217 commands as well as to other declaration commands created as types.
218 The syntax for an assignment is of the form:
219 varname=word
221 varname[word]=word
222 No space is permitted between varname and the = or between = and
223 word.
224 varname=(assign_list)
226 No space is permitted between varname and the =. The variable
227 varname is unset before the assignment. An assign_list can be
228 one of the following:
229 word ...
230 Indexed array assignment.
231 [word]=word ...
232 Associative array assignment. If preceded by
233 typeset -a this will create an indexed array
234 instead.
235 assignment ...
236 Compound variable assignment. This creates a
237 compound variable varname with sub-variables of
238 the form varname.name, where name is the name
239 portion of assignment. The value of varname will
240 contain all the assignment elements. Additional
241 assignments made to sub-variables of varname will
242 also be displayed as part of the value of var‐
243 name. If no assignments are specified, varname
244 will be a compound variable allowing subsequence
245 child elements to be defined.
246 typeset [options] assignment ...
247 Nested variable assignment. Multiple assignments
248 can be specified by separating each of them with
249 a ;. The previous value is unset before the
250 assignment. Other declaration commands such as
251 readonly, enum, and other declaration commands
252 can be used in place of typeset.
253 . filename
254 Include the assignment commands contained in
255 filename.
256 In addition, a += can be used in place of the = to signify adding to or
258 appending to the previous value. When += is applied to an arithmetic
259 type, word is evaluated as an arithmetic expression and added to the
260 current value. When applied to a string variable, the value defined by
261 word is appended to the value. For compound assignments, the previous
262 value is not unset and the new values are appended to the current ones
263 provided that the types are compatible.
264 The right hand side of a variable assignment undergoes all the expan‐
266 sion listed below except word splitting, brace expansion, and file name
267 generation. When the left hand side is an assignment is a compound
268 variable and the right hand is the name of a compound variable, the
269 compound variable on the right will be copied or appended to the com‐
270 pound variable on the left.
271 Comments.
273 A word beginning with # causes that word and all the following charac‐
274 ters up to a new-line to be ignored.
275 Aliasing.
276 The first word of each command is replaced by the text of an alias if
277 an alias for this word has been defined. An alias name consists of any
278 number of characters excluding metacharacters, quoting characters, file
279 expansion characters, parameter expansion and command substitution
280 characters, the characters / and =. The replacement string can contain
281 any valid shell script including the metacharacters listed above. The
282 first word of each command in the replaced text, other than any that
283 are in the process of being replaced, will be tested for aliases. If
284 the last character of the alias value is a blank then the word follow‐
285 ing the alias will also be checked for alias substitution. Aliases can
286 be used to redefine built-in commands but cannot be used to redefine
287 the reserved words listed above. Aliases can be created and listed
288 with the alias command and can be removed with the unalias command.
289 Aliasing is performed when scripts are read, not while they are exe‐
290 cuted. Therefore, for an alias to take effect, the alias definition
291 command has to be executed before the command which references the
292 alias is read.
293 The following aliases are compiled into the shell but can be unset or
294 redefined:
295 autoload=′typeset -fu′
296 bool=′_Bool′
297 command=′command ′
298 compound=′typeset -C′
299 fc=hist
300 float=′typeset -lE′
301 functions=′typeset -f′
302 hash=′alias -t --′
303 history=′hist -l′
304 integer=′typeset -li′
305 nameref=′typeset -n′
306 nohup=′nohup ′
307 r=′hist -s′
308 redirect=′command exec′
309 source=′command .′
310 stop=′kill -s STOP′
311 suspend=′kill -s STOP "$$"′
312 type=′whence -v′
313 Tilde Substitution.
315 After alias substitution is performed, each word is checked to see if
316 it begins with an unquoted ∼. For tilde substitution, word also refers
317 to the word portion of parameter expansion (see Parameter Expansion
318 below). If it does, then the word up to a / is checked to see if it
319 matches a user name in the password database (See getpwname(3).) If a
320 match is found, the ∼ and the matched login name are replaced by the
321 login directory of the matched user. If no match is found, the origi‐
322 nal text is left unchanged. A ∼ by itself, or in front of a /, is
323 replaced by $HOME. A ∼ followed by a + or - is replaced by the value
324 of $PWD and $OLDPWD respectively. A ∼ followed by {fd} where fd is a
325 file descriptor number or the name of a variable whose value is a file
326 descriptor, is replaced by a string that is the equivalent to the path
327 name of the file or directory corresponding to this file descriptor.
328 In addition, when expanding a variable assignment, tilde substitution
330 is attempted when the value of the assignment begins with a ∼, and when
331 a ∼ appears after a :. The : also terminates a ∼ login name.
332 Command Substitution.
334 The standard output from a command list enclosed in parentheses pre‐
335 ceded by a dollar sign ( $(list) ), or in a brace group preceded by a
336 dollar sign ( ${ list;} ), or in a pair of grave accents (``) may be
337 used as part or all of a word; trailing new-lines are removed. In the
338 second case, the { and } are treated as a reserved words so that { must
339 be followed by a blank and } must appear at the beginning of the line
340 or follow a ;. In the third (obsolete) form, the string between the
341 quotes is processed for special quoting characters before the command
342 is executed (see Quoting below). The command substitution $(cat file)
343 can be replaced by the equivalent but faster $(<file). The command
344 substitution $(n<#) will expand to the current byte offset for file
345 descriptor n. Except for the second form, the command list is run in a
346 subshell so that no side effects are possible. For the second form,
347 the final } will be recognized as a reserved word after any token.
348 Arithmetic Substitution.
350 An arithmetic expression enclosed in double parentheses preceded by a
351 dollar sign ( $(()) ) is replaced by the value of the arithmetic
352 expression within the double parentheses.
353 Process Substitution.
355 Each command argument of the form <(list) or >(list) will run process
356 list asynchronously connected to some file in /dev/fd if this directory
357 exists, or else a fifo a temporary directory. The name of this file
358 will become the argument to the command. If the form with > is
359 selected then writing on this file will provide input for list. If <
360 is used, then the file passed as an argument will contain the output of
361 the list process. For example,
362 paste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1)
364 >(process2)
365 cuts fields 1 and 3 from the files file1 and file2 respectively, pastes
367 the results together, and sends it to the processes process1 and
368 process2, as well as putting it onto the standard output. Note that
369 the file, which is passed as an argument to the command, is a UNIX
370 pipe(2) so programs that expect to lseek(2) on the file will not work.
371 Process substitution of the form <(list) can also be used with the <
373 redirection operator which causes the output of list to be standard
374 input or the input for whatever file descriptor is specified.
375 Parameter Expansion.
377 A parameter is a variable, one or more digits, or any of the characters
378 *, @, #, ?, -, $, and !. A variable is denoted by a vname. To create
379 a variable whose vname contains a ., a variable whose vname consists of
380 everything before the last . must already exist. A variable has a
381 value and zero or more attributes. Variables can be assigned values
382 and attributes by using the typeset special built-in command. The
383 attributes supported by the shell are described later with the typeset
384 special built-in command. Exported variables pass values and
385 attributes to the environment.
386 The shell supports both indexed and associative arrays. An element of
388 an array variable is referenced by a subscript. A subscript for an
389 indexed array is denoted by an arithmetic expression (see Arithmetic
390 evaluation below) between a [ and a ]. To assign values to an indexed
391 array, use vname=(value ...) or set -A vname value ... . The value of
392 all non-negative subscripts must be in the range of 0 through
393 4,194,303. A negative subscript is treated as an offset from the maxi‐
394 mum current index +1 so that -1 refers to the last element. Indexed
395 arrays can be declared with the -a option to typeset. Indexed arrays
396 need not be declared. Any reference to a variable with a valid sub‐
397 script is legal and an array will be created if necessary.
398 An associative array is created with the -A option to typeset. A sub‐
400 script for an associative array is denoted by a string enclosed between
401 [ and ].
402 Referencing any array without a subscript is equivalent to referencing
404 the array with subscript 0.
405 The value of a variable may be assigned by writing:
407 vname=value [ vname=value ] ...
409 or
411 vname[subscript]=value [ vname[subscript]=value ] ...
412 Note that no space is allowed before or after the =.
413 Attributes assigned by the typeset special built-in command apply to
414 all elements of the array. An array element can be a simple variable,
415 a compound variable or an array variable. An element of an indexed
416 array can be either an indexed array or an associative array. An ele‐
417 ment of an associative array can also be either. To refer to an array
418 element that is part of an array element, concatenate the subscript in
419 brackets. For example, to refer to the foobar element of an associa‐
420 tive array that is defined as the third element of the indexed array,
421 use ${vname[3][foobar]}
422 A nameref is a variable that is a reference to another variable. A
423 nameref is created with the -n attribute of typeset. The value of the
424 variable at the time of the typeset command becomes the variable that
425 will be referenced whenever the nameref variable is used. The name of
426 a nameref cannot contain a .. When a variable or function name con‐
427 tains a ., and the portion of the name up to the first . matches the
428 name of a nameref, the variable referred to is obtained by replacing
429 the nameref portion with the name of the variable referenced by the
430 nameref. If a nameref is used as the index of a for loop, a name ref‐
431 erence is established for each item in the list. A nameref provides a
432 convenient way to refer to the variable inside a function whose name is
433 passed as an argument to a function. For example, if the name of a
434 variable is passed as the first argument to a function, the command
435 typeset -n var=$1
436 inside the function causes references and assignments to var to be ref‐
437 erences and assignments to the variable whose name has been passed to
438 the function.
439 If any of the floating point attributes, -E, -F, or -X, or the integer
440 attribute, -i, is set for vname, then the value is subject to arith‐
441 metic evaluation as described below.
442 Positional parameters, parameters denoted by a number, may be assigned
443 values with the set special built-in command. Parameter $0 is set from
444 argument zero when the shell is invoked.
445 The character $ is used to introduce substitutable parameters.
446 ${parameter}
447 The shell reads all the characters from ${ to the matching } as
448 part of the same word even if it contains braces or metacharac‐
449 ters. The value, if any, of the parameter is substituted. The
450 braces are required when parameter is followed by a letter,
451 digit, or underscore that is not to be interpreted as part of
452 its name, when the variable name contains a .. The braces are
453 also required when a variable is subscripted unless it is part
454 of an Arithmetic Expression or a Conditional Expression. If
455 parameter is one or more digits then it is a positional parame‐
456 ter. A positional parameter of more than one digit must be
457 enclosed in braces. If parameter is * or @, then all the posi‐
458 tional parameters, starting with $1, are substituted (separated
459 by a field separator character). If an array vname with last
460 subscript * @, or for index arrays of the form sub1 .. sub2.
461 is used, then the value for each of the elements between sub1
462 and sub2 inclusive (or all elements for * and @) is substituted,
463 separated by the first character of the value of IFS.
464 ${#parameter}
465 If parameter is * or @, the number of positional parameters is
466 substituted. Otherwise, the length of the value of the parame‐
467 ter is substituted.
468 ${#vname[*]}
469 ${#vname[@]}
470 The number of elements in the array vname is substituted.
471 ${@vname}
473 Expands to the type name (See Type Variables below) or
474 attributes of the variable referred to by vname.
475 ${$parameter}
476 If $parameter expands to the name of a variable, this expands to
477 the value of that variable. Otherwise, it expands to the empty
478 string. It is undefined for special parameters.
479 ${!vname}
480 Expands to the name of the variable referred to by vname. This
481 will be vname except when vname is a name reference.
482 ${!vname[subscript]}
483 Expands to name of the subscript unless subscript is *, @. or
484 of the form sub1 .. sub2. When subscript is *, the list of
485 array subscripts for vname is generated. For a variable that is
486 not an array, the value is 0 if the variable is set. Otherwise
487 it is null. When subscript is @, same as above, except that
488 when used in double quotes, each array subscript yields a sepa‐
489 rate argument. When subscript is of the form sub1 .. sub2 it
490 expands to the list of subscripts between sub1 and sub2 inclu‐
491 sive using the same quoting rules as @.
492 ${!prefix*}
493 Expands to the names of the variables whose names begin with
494 prefix.
495 ${parameter:-word}
496 If parameter is set and is non-null then substitute its value;
497 otherwise substitute word.
498 ${parameter:=word}
499 If parameter is not set or is null then set it to word; the
500 value of the parameter is then substituted. Positional parame‐
501 ters may not be assigned to in this way.
502 ${parameter:?word}
503 If parameter is set and is non-null then substitute its value;
504 otherwise, print word and exit from the shell (if not interac‐
505 tive). If word is omitted then a standard message is printed.
506 ${parameter:+word}
507 If parameter is set and is non-null then substitute word; other‐
508 wise substitute nothing.
509 In the above, word is not evaluated unless it is to be used as the sub‐
510 stituted string, so that, in the following example, pwd is executed
511 only if d is not set or is null:
512 print ${d:-$(pwd)}
513 If the colon ( : ) is omitted from the above expressions, then the
514 shell only checks whether parameter is set or not.
515 ${parameter:offset:length}
516 ${parameter:offset}
517 Expands to the portion of the value of parameter starting at the
518 character (counting from 0) determined by expanding offset as an
519 arithmetic expression and consisting of the number of characters
520 determined by the arithmetic expression defined by length. In
521 the second form, the remainder of the value is used. If A nega‐
522 tive offset counts backwards from the end of parameter. Note
523 that one or more blanks is required in front of a minus sign to
524 prevent the shell from interpreting the operator as :-. If
525 parameter is * or @, or is an array name indexed by * or @, then
526 offset and length refer to the array index and number of ele‐
527 ments respectively. A negative offset is taken relative to one
528 greater than the highest subscript for indexed arrays. The
529 order for associate arrays is unspecified.
530 ${parameter#pattern}
531 ${parameter##pattern}
532 If the shell pattern matches the beginning of the value of
533 parameter, then the value of this expansion is the value of the
534 parameter with the matched portion deleted; otherwise the value
535 of this parameter is substituted. In the first form the small‐
536 est matching pattern is deleted and in the second form the
537 largest matching pattern is deleted. When parameter is @, *, or
538 an array variable with subscript @ or *, the substring operation
539 is applied to each element in turn.
540 ${parameter%pattern}
542 ${parameter%%pattern}
543 If the shell pattern matches the end of the value of parameter,
544 then the value of this expansion is the value of the parameter
545 with the matched part deleted; otherwise substitute the value of
546 parameter. In the first form the smallest matching pattern is
547 deleted and in the second form the largest matching pattern is
548 deleted. When parameter is @, *, or an array variable with sub‐
549 script @ or *, the substring operation is applied to each ele‐
550 ment in turn.
551 ${parameter/pattern/string}
553 ${parameter//pattern/string}
554 ${parameter/#pattern/string}
555 ${parameter/%pattern/string}
556 Expands parameter and replaces the longest match of pattern with
557 the given string. Each occurrence of \n in string is replaced
558 by the portion of parameter that matches the n-th sub-pattern.
559 In the first form, only the first occurrence of pattern is
560 replaced. In the second form, each match for pattern is
561 replaced by the given string. The third form restricts the pat‐
562 tern match to the beginning of the string while the fourth form
563 restricts the pattern match to the end of the string. When
564 string is null, the pattern will be deleted and the / in front
565 of string may be omitted. When parameter is @, *, or an array
566 variable with subscript @ or *, the substitution operation is
567 applied to each element in turn. In this case, the string por‐
568 tion of word will be re-evaluated for each element.
569 ${parameter^pattern}
571 ${parameter^^pattern}
572 ${parameter,pattern}
573 ${parameter,,pattern}
574 Case modification. This expansion modifies the case of alpha‐
575 betic characters in parameter. The pattern is expanded to pro‐
576 duce a pattern just as in pathname expansion. The ^ operator
577 converts lowercase characters matching pattern to uppercase.
578 The , operator converts matching uppercase characters to lower‐
579 case. The ^^ and ,, expansions convert all matched charac‐
580 ter in the expanded value. The ^ and , expansions match and
581 convert only the first character in the expanded value. If pat‐
582 tern is omitted it is treated like a ?, which matches every
583 character. If parameter is @ or *, or an array subscripted by @
584 or *, the case modification operation is applied to each ele‐
585 ment.
586 The following parameters are automatically set by the shell:
589 # The number of positional parameters in decimal.
590 - Options supplied to the shell on invocation or by the set
591 command.
592 ? The decimal value returned by the last executed command.
593 $ The process number of this shell.
594 _ Initially, the value of _ is an absolute pathname of the
595 shell or script being executed as passed in the environ‐
596 ment. Subsequently it is assigned the last argument of
597 the previous command. This parameter is not set for com‐
598 mands which are asynchronous. This parameter is also
599 used to hold the name of the matching MAIL file when
600 checking for mail. While defining a compound variable or
601 a type, _ is initialized as a reference to the compound
602 variable or type. When a discipline function is invoked,
603 _ is initialized as a reference to the variable associ‐
604 ated with the call to this function. Finally when _ is
605 used as the name of the first variable of a type defini‐
606 tion, the new type is derived from the type of the first
607 variable (See Type Variables below.).
608 ! The process id or the pool name and job number of the
609 last background command invoked or the most recent job
610 put in the background with the bg built-in command.
611 Background jobs started in a named pool will be in the
612 form pool.number where pool is the pool name and number
613 is the job number within that pool.
614 .sh.command
615 When processing a DEBUG trap, this variable contains the
616 current command line that is about to run.
617 .sh.edchar
618 This variable contains the value of the keyboard charac‐
619 ter (or sequence of characters if the first character is
620 an ESC, ascii 033) that has been entered when processing
621 a KEYBD trap (see Key Bindings below). If the value is
622 changed as part of the trap action, then the new value
623 replaces the key (or key sequence) that caused the trap.
624 .sh.edcol
625 The character position of the cursor at the time of the
626 most recent KEYBD trap.
627 .sh.edmode
628 The value is set to ESC when processing a KEYBD trap
629 while in vi insert mode. (See Vi Editing Mode below.)
630 Otherwise, .sh.edmode is null when processing a KEYBD
631 trap.
632 .sh.edtext
633 The characters in the input buffer at the time of the
634 most recent KEYBD trap. The value is null when not pro‐
635 cessing a KEYBD trap.
636 .sh.file
637 The pathname of the file than contains the current com‐
638 mand.
639 .sh.fun
640 The name of the current function that is being executed.
641 .sh.level
642 Set to the current function depth. This can be changed
643 inside a DEBUG trap and will set the context to the spec‐
644 ified level.
645 .sh.lineno
646 Set during a DEBUG trap to the line number for the caller
647 of each function.
648 .sh.match
649 An indexed array which stores the most recent match and
650 sub-pattern matches after conditional pattern matches
651 that match and after variables expansions using the oper‐
652 ators #, %, or /. The 0-th element stores the complete
653 match and the i-th. element stores the i-th submatch.
654 For // the array is two dimensional with the first sub‐
655 script indicating the most recent match and sub-pattern
656 match and the second script indicating which match with 0
657 representing the first match. The .sh.match variable
658 becomes unset when the variable that has expanded is
659 assigned a new value.
660 .sh.math
661 Used for defining arithmetic functions (see Arithmetic
662 evaluation below). and stores the list of user defined
663 arithmetic functions.
664 .sh.name
665 Set to the name of the variable at the time that a disci‐
666 pline function is invoked.
667 .sh.op_astbin
668 The directory where several shell built-in commands are
669 bound to. The default is /opt/ast/bin. When the value
670 is /bin, then builtins will be bound to /bin or /usr/bin
671 depending on where the executable is found. This vari‐
672 able can be set by including it in the SH_OPTIONS vari‐
673 able.
674 .sh.pgrp
675 The current process group of this shell.
676 .sh.pwdfd
677 The file descriptor number for the present working direc‐
678 tory.
679 .sh.sig
680 Set when executing a trap to the information contained in
681 the siginfo_t structure (See siginfo(2) for a description
682 of this structure.)
683 .sh.subscript
684 Set to the name subscript of the variable at the time
685 that a discipline function is invoked.
686 .sh.subshell
687 The current depth for subshells and command substitution.
688 .sh.value
689 Set to the value of the variable at the time that the set
690 or append discipline function is invoked. When a user
691 defined arithmetic function is invoked, the value of
692 .sh.value is saved and .sh.value is set to long double
693 precision floating point. .sh.value is restored when the
694 function returns.
695 .sh.version
696 Set to a value that identifies the version of this shell.
697 KSH_VERSION
698 A name reference to .sh.version.
699 LINENO The current line number within the script or function
700 being executed.
701 OLDPWD The previous working directory set by the cd command.
702 OPTARG The value of the last option argument processed by the
703 getopts built-in command.
704 OPTIND The index of the last option argument processed by the
705 getopts built-in command.
706 PPID The process number of the parent of the shell.
707 PWD The present working directory set by the cd command.
708 RANDOM Each time this variable is referenced, a random integer,
709 uniformly distributed between 0 and 32767, is generated.
710 The sequence of random numbers can be initialized by
711 assigning a numeric value to RANDOM.
712 REPLY This variable is set by the select statement and by the
713 read built-in command when no arguments are supplied.
714 SECONDS
715 Each time this variable is referenced, the number of sec‐
716 onds since shell invocation is returned. If this vari‐
717 able is assigned a value, then the value returned upon
718 reference will be the value that was assigned plus the
719 number of seconds since the assignment.
720 SHLVL An integer variable the is incremented each time the
721 shell is invoked and is exported. If SHLVL is not in the
722 environment when the shell is invoked, it is set to 1.
723 The following variables are used by the shell:
725 CDPATH The search path for the cd command.
726 COLUMNS
727 If this variable is set, the value is used to define the
728 width of the edit window for the shell edit modes and for
729 printing select lists.
730 EDITOR If the VISUAL variable is not set, the value of this
731 variable will be checked for the patterns as described
732 with VISUAL below and the corresponding editing option
733 (see Special Command set below) will be turned on.
734 ENV If this variable is set, then parameter expansion, com‐
735 mand substitution, and arithmetic substitution are per‐
736 formed on the value to generate the pathname of the
737 script that will be executed when the shell is invoked
738 interactively (see Invocation below). This file is typi‐
739 cally used for alias and function definitions. The
740 default value is $HOME/.kshrc. On systems that support a
741 system wide /etc/ksh.kshrc initialization file, if the
742 filename generated by the expansion of ENV begins with
743 /./ or ././ the system wide initialization file will not
744 be executed.
745 FCEDIT Obsolete name for the default editor name for the hist
746 command. FCEDIT is not used when HISTEDIT is set.
747 FIGNORE
748 A pattern that defines the set of filenames that will be
749 ignored when performing filename matching.
750 FPATH The search path for function definitions. The directo‐
751 ries in this path are searched for a file with the same
752 name as the function or command when a function with the
753 -u attribute is referenced and when a command is not
754 found. If an executable file with the name of that com‐
755 mand is found, then it is read and executed in the cur‐
756 rent environment. Unlike PATH, the current directory
757 must be represented explicitly by . rather than by adja‐
758 cent : characters or a beginning or ending :.
759 HISTCMD
760 Number of the current command in the history file.
761 HISTEDIT
762 Name for the default editor name for the hist command.
763 HISTFILE
764 If this variable is set when the shell is invoked, then
765 the value is the pathname of the file that will be used
766 to store the command history (see Command Re-entry
767 below).
768 HISTSIZE
769 If this variable is set when the shell is invoked, then
770 the number of previously entered commands that are acces‐
771 sible by this shell will be greater than or equal to this
772 number. The default is 512.
773 HOME The default argument (home directory) for the cd command.
774 IFS Internal field separators, normally space, tab, and new-
775 line that are used to separate the results of command
776 substitution or parameter expansion and to separate
777 fields with the built-in command read. The first charac‐
778 ter of the IFS variable is used to separate arguments for
779 the "$*" substitution (see Quoting below). Each single
780 occurrence of an IFS character in the string to be split,
781 that is not in the isspace character class, and any adja‐
782 cent characters in IFS that are in the isspace character
783 class, delimit a field. One or more characters in IFS
784 that belong to the isspace character class, delimit a
785 field. In addition, if the same isspace character
786 appears consecutively inside IFS, this character is
787 treated as if it were not in the isspace class, so that
788 if IFS consists of two tab characters, then two adjacent
789 tab characters delimit a null field.
790 JOBMAX This variable defines the maximum number running back‐
791 ground jobs that can run at a time. When this limit is
792 reached, the shell will wait for a job to complete before
793 staring a new job.
794 LANG This variable determines the locale category for any cat‐
795 egory not specifically selected with a variable starting
796 with LC_ or LANG.
797 LC_ALL This variable overrides the value of the LANG variable
798 and any other LC_ variable.
799 LC_COLLATE
800 This variable determines the locale category for charac‐
801 ter collation information.
802 LC_CTYPE
803 This variable determines the locale category for charac‐
804 ter handling functions. It determines the character
805 classes for pattern matching (see File Name Generation
806 below).
807 LC_NUMERIC
808 This variable determines the locale category for the dec‐
809 imal point character.
810 LINES If this variable is set, the value is used to determine
811 the column length for printing select lists. Select
812 lists will print vertically until about two-thirds of
813 LINES lines are filled.
814 MAIL If this variable is set to the name of a mail file and
815 the MAILPATH variable is not set, then the shell informs
816 the user of arrival of mail in the specified file.
817 MAILCHECK
818 This variable specifies how often (in seconds) the shell
819 will check for changes in the modification time of any of
820 the files specified by the MAILPATH or MAIL variables.
821 The default value is 600 seconds. When the time has
822 elapsed the shell will check before issuing the next
823 prompt.
824 MAILPATH
825 A colon ( : ) separated list of file names. If this
826 variable is set, then the shell informs the user of any
827 modifications to the specified files that have occurred
828 within the last MAILCHECK seconds. Each file name can be
829 followed by a ? and a message that will be printed. The
830 message will undergo parameter expansion, command substi‐
831 tution, and arithmetic substitution with the variable $_
832 defined as the name of the file that has changed. The
833 default message is you have mail in $_.
834 PATH The search path for commands (see Execution below). The
835 user may not change PATH if executing under rksh (except
836 in .profile).
837 PS1 The value of this variable is expanded for parameter
838 expansion, command substitution, and arithmetic substitu‐
839 tion to define the primary prompt string which by default
840 is ``$ ''. The character ! in the primary prompt string
841 is replaced by the command number (see Command Re-entry
842 below). Two successive occurrences of ! will produce a
843 single ! when the prompt string is printed.
844 PS2 Secondary prompt string, by default ``> ''.
845 PS3 Selection prompt string used within a select loop, by
846 default ``#? ''.
847 PS4 The value of this variable is expanded for parameter
848 evaluation, command substitution, and arithmetic substi‐
849 tution and precedes each line of an execution trace. By
850 default, PS4 is ``+ ''. In addition when PS4 is unset,
851 the execution trace prompt is also ``+ ''.
852 SH_OPTIONS
853 The value consists of blank separated name=value words.
854 For each name that is the name of a known option the
855 variable .sh.opt_name is assigned value. Currently the
856 only valid option name is astbin.
857 SHELL The pathname of the shell is kept in the environment. At
858 invocation, if the basename of this variable is rsh,
859 rksh, or krsh, then the shell becomes restricted. If it
860 is pfsh or pfksh, then the shell becomes a profile shell
861 (see pfexec(1)).
862 TIMEFORMAT
863 The value of this parameter is used as a format string
864 specifying how the timing information for pipelines pre‐
865 fixed with the time reserved word should be displayed.
866 The % character introduces a format sequence that is
867 expanded to a time value or other information. The for‐
868 mat sequences and their meanings are as follows.
869 %% A literal %.
870 %[p][l]R The elapsed time in seconds.
871 %[p][l]U The number of CPU seconds spent in user mode.
872 %[p][l]S The number of CPU seconds spent in system mode.
873 %[p][l]C The total number of CPU seconds; i.e., the sum
874 of the time spent in user plus system mode.
875 %P The CPU percentage (i.e., CPU utilization),
876 computed as C / R.
877 The brackets denote optional portions. The optional p is
879 a digit specifying the precision, the number of frac‐
880 tional digits after a decimal point. A value of 0 causes
881 no decimal point or fraction to be output. At most three
882 places after the decimal point can be displayed; values
883 of p greater than 3 are treated as 3. If p is not speci‐
884 fied, the value 3 is used.
885 The optional l specifies a longer format, including hours
887 if greater than zero, minutes, and seconds of the form
888 HHhMMmSS.FFs. The value of p determines whether or not
889 the fraction is included.
890 All other characters are output without change and a
892 trailing newline is added. If unset, the default value,
893 $'\nreal\t%2lR\nuser\t%2lU\nsys%2lS', is used. If the
894 value is null, no timing information is displayed.
895 TMOUT If set to a value greater than zero, TMOUT will be the
897 default timeout value for the read built-in command. The
898 select compound command terminates after TMOUT seconds
899 when input is from a terminal. Otherwise, the shell will
900 terminate if a line is not entered within the prescribed
901 number of seconds while reading from a terminal. (Note
902 that the shell can be compiled with a maximum bound for
903 this value which cannot be exceeded.)
904 VISUAL If the value of this variable matches the pattern
906 *[Vv][Ii]*, then the vi option (see Special Command set
907 below) is turned on. If the value matches the pattern
908 *gmacs* , the gmacs option is turned on. If the value
909 matches the pattern *macs*, then the emacs option will be
910 turned on. The value of VISUAL overrides the value of
911 EDITOR.
912 The shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK,
914 FCEDIT, TMOUT and IFS, while HOME, SHELL, ENV, and MAIL are not set at
915 all by the shell (although HOME is set by login(1)). On some systems
916 MAIL and SHELL are also set by login(1).
917 Field Splitting.
919 After parameter expansion and command substitution, the results of sub‐
920 stitutions are scanned for the field separator characters (those found
921 in IFS) and split into distinct fields where such characters are found.
922 Explicit null fields ("" or ′′) are retained. Implicit null fields
923 (those resulting from parameters that have no values or command substi‐
924 tutions with no output) are removed.
925 If the braceexpand (-B) option is set then each of the fields resulting
927 from IFS are checked to see if they contain one or more of the brace
928 patterns {*,*}, {l1..l2} , {n1..n2} , {n1..n2% fmt} , {n1..n2 ..n3} ,
929 or {n1..n2 ..n3%fmt} , where * represents any character, l1,l2 are let‐
930 ters and n1,n2,n3 are signed numbers and fmt is a format specified as
931 used by printf. In each case, fields are created by prepending the
932 characters before the { and appending the characters after the } to
933 each of the strings generated by the characters between the { and }.
934 The resulting fields are checked to see if they have any brace pat‐
935 terns.
936 In the first form, a field is created for each string between { and ,,
938 between , and ,, and between , and }. The string represented by * can
939 contain embedded matching { and } without quoting. Otherwise, each {
940 and } with * must be quoted.
941 In the seconds form, l1 and l2 must both be either upper case or both
943 be lower case characters in the C locale. In this case a field is cre‐
944 ated for each character from l1 thru l2.
945 In the remaining forms, a field is created for each number starting at
947 n1 and continuing until it reaches n2 incrementing n1 by n3. The cases
948 where n3 is not specified behave as if n3 where 1 if n1<=n2 and -1 oth‐
949 erwise. If forms which specify %fmt any format flags, widths and pre‐
950 cisions can be specified and fmt can end in any of the specifiers
951 cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to the 8
952 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx, z04bx and z4cx.
953 File Name Generation.
955 Following splitting, each field is scanned for the characters *, ?, (,
956 and [ unless the -f option has been set. If one of these characters
957 appears, then the word is regarded as a pattern. Each file name compo‐
958 nent that contains any pattern character is replaced with a lexico‐
959 graphically sorted set of names that matches the pattern from that
960 directory. If no file name is found that matches the pattern, then
961 that component of the filename is left unchanged unless the pattern is
962 prefixed with ∼(N) in which case it is removed as described below. If
963 FIGNORE is set, then each file name component that matches the pattern
964 defined by the value of FIGNORE is ignored when generating the matching
965 filenames. The names . and .. are also ignored. If FIGNORE is not
966 set, the character . at the start of each file name component will be
967 ignored unless the first character of the pattern corresponding to this
968 component is the character . itself. Note, that for other uses of
969 pattern matching the / and . are not treated specially.
970 * Matches any string, including the null string. When used
972 for filename expansion, if the globstar option is on, an
973 isolated pattern of two adjacent *'s will match all files
974 and zero or more directories and subdirectories. If fol‐
975 lowed by a / then only directories and subdirectories
976 will match.
977 ? Matches any single character.
978 [...] Matches any one of the enclosed characters. A pair of
979 characters separated by - matches any character lexically
980 between the pair, inclusive. If the first character fol‐
981 lowing the opening [ is a ! or ^ then any character not
982 enclosed is matched. A - can be included in the charac‐
983 ter set by putting it as the first or last character.
984 Within [ and ], character classes can be specified with
985 the syntax [:class:] where class is one of the following
986 classes defined in the ANSI-C standard: (Note that word
987 is equivalent to alnum plus the character _.)
988 alnum alpha blank cntrl digit graph lower print punct
989 space upper word xdigit
990 Within [ and ], an equivalence class can be specified
991 with the syntax [=c=] which matches all characters with
992 the same primary collation weight (as defined by the cur‐
993 rent locale) as the character c. Within [ and ], [.sym‐
994 bol.] matches the collating symbol symbol.
995 A pattern-list is a list of one or more patterns separated from each
996 other with a & or ⎪. A & signifies that all patterns must be matched
997 whereas ⎪ requires that only one pattern be matched. Composite pat‐
998 terns can be formed with one or more of the following sub-patterns:
999 ?(pattern-list)
1000 Optionally matches any one of the given patterns.
1001 *(pattern-list)
1002 Matches zero or more occurrences of the given patterns.
1003 +(pattern-list)
1004 Matches one or more occurrences of the given patterns.
1005 {n}(pattern-list)
1006 Matches n occurrences of the given patterns.
1007 {m,n}(pattern-list)
1008 Matches from m to n occurrences of the given patterns.
1009 If m is omitted, 0 will be used. If n is omitted at
1010 least m occurrences will be matched.
1011 @(pattern-list)
1012 Matches exactly one of the given patterns.
1013 !(pattern-list)
1014 Matches anything except one of the given patterns.
1015 By default, each pattern, or sub-pattern will match the longest string
1016 possible consistent with generating the longest overall match. If more
1017 than one match is possible, the one starting closest to the beginning
1018 of the string will be chosen. However, for each of the above compound
1019 patterns a - can be inserted in front of the ( to cause the shortest
1020 match to the specified pattern-list to be used.
1021 When pattern-list is contained within parentheses, the backslash char‐
1023 acter \ is treated specially even when inside a character class. All
1024 ANSI-C character escapes are recognized and match the specified charac‐
1025 ter. In addition the following escape sequences are recognized:
1026 \d Matches any character in the digit class.
1027 \D Matches any character not in the digit class.
1028 \s Matches any character in the space class.
1029 \S Matches any character not in the space class.
1030 \w Matches any character in the word class.
1031 \W Matches any character not in the word class.
1032 A pattern of the form %(pattern-pair(s)) is a sub-pattern that can be
1034 used to match nested character expressions. Each pattern-pair is a two
1035 character sequence which cannot contain & or ⎪. The first pattern-pair
1036 specifies the starting and ending characters for the match. Each sub‐
1037 sequent pattern-pair represents the beginning and ending characters of
1038 a nested group that will be skipped over when counting starting and
1039 ending character matches. The behavior is unspecified when the first
1040 character of a pattern-pair is alpha-numeric except for the following:
1041 D Causes the ending character to terminate the search for
1042 this pattern without finding a match.
1043 E Causes the ending character to be interpreted as an
1044 escape character.
1045 L Causes the ending character to be interpreted as a quote
1046 character causing all characters to be ignored when look‐
1047 ing for a match.
1048 Q Causes the ending character to be interpreted as a quote
1049 character causing all characters other than any escape
1050 character to be ignored when looking for a match.
1051 Thus, %({}Q"E\), matches characters starting at { until the matching }
1052 is found not counting any { or } that is inside a double quoted string
1053 or preceded by the escape character \. Without the {} this pattern
1054 matches any C language string.
1055 Each sub-pattern in a composite pattern is numbered, starting at 1, by
1057 the location of the ( within the pattern. The sequence \n, where n is
1058 a single digit and \n comes after the n-th. sub-pattern, matches the
1059 same string as the sub-pattern itself.
1060 Finally a pattern can contain sub-patterns of the form ∼(options:pat‐
1062 tern-list), where either options or :pattern-list can be omitted.
1063 Unlike the other compound patterns, these sub-patterns are not counted
1064 in the numbered sub-patterns. :pattern-list must be omitted for
1065 options F, G, N , and V below. If options is present, it can consist
1066 of one or more of the following:
1067 + Enable the following options. This is the default.
1068 - Disable the following options.
1069 E The remainder of the pattern uses extended regular
1070 expression syntax like the egrep(1) command.
1071 F The remainder of the pattern uses fgrep(1) expression
1072 syntax.
1073 G The remainder of the pattern uses basic regular expres‐
1074 sion syntax like the grep(1) command.
1075 K The remainder of the pattern uses shell pattern syntax.
1076 This is the default.
1077 N This is ignored. However, when it is the first letter
1078 and is used with file name generation, and no matches
1079 occur, the file pattern expands to the empty string.
1080 X The remainder of the pattern uses augmented regular
1081 expression syntax like the xgrep(1) command.
1082 P The remainder of the pattern uses perl(1) regular expres‐
1083 sion syntax. Not all perl regular expression syntax is
1084 currently implemented.
1085 V The remainder of the pattern uses System V regular
1086 expression syntax.
1087 i Treat the match as case insensitive.
1088 g File the longest match (greedy). This is the default.
1089 l Left anchor the pattern. This is the default for K style
1090 patterns.
1091 r Right anchor the pattern. This is the default for K
1092 style patterns.
1093 If both options and :pattern-list are specified, then the options apply
1094 only to pattern-list. Otherwise, these options remain in effect until
1095 they are disabled by a subsequent ∼(...) or at the end of the sub-pat‐
1096 tern containing ∼(...).
1097 Quoting.
1099 Each of the metacharacters listed earlier (see Definitions above) has a
1100 special meaning to the shell and causes termination of a word unless
1101 quoted. A character may be quoted (i.e., made to stand for itself) by
1102 preceding it with a \. The pair \new-line is removed. All characters
1103 enclosed between a pair of single quote marks (′′) that is not preceded
1104 by a $ are quoted. A single quote cannot appear within the single
1105 quotes. A single quoted string preceded by an unquoted $ is processed
1106 as an ANSI-C string except for the following:
1107 \0 Causes the remainder of the string to be ignored.
1108 \E Equivalent to the escape character (ascii 033),
1109 \e Equivalent to the escape character (ascii 033),
1110 \cx Expands to the character control-x.
1111 \C[.name.]
1112 Expands to the collating element name.
1113 Inside double quote marks (""), parameter and command substitution
1115 occur and \ quotes the characters \, `, ", and $. A $ in front of a
1116 double quoted string will be ignored in the "C" or "POSIX" locale, and
1117 may cause the string to be replaced by a locale specific string other‐
1118 wise. The meaning of $* and $@ is identical when not quoted or when
1119 used as a variable assignment value or as a file name. However, when
1120 used as a command argument, "$*" is equivalent to "$1d$2d...", where d
1121 is the first character of the IFS variable, whereas "$@" is equivalent
1122 to "$1" "$2" .... Inside grave quote marks (``), \ quotes the charac‐
1123 ters \, `, and $. If the grave quotes occur within double quotes, then
1124 \ also quotes the character ".
1125 The special meaning of reserved words or aliases can be removed by
1127 quoting any character of the reserved word. The recognition of func‐
1128 tion names or built-in command names listed below cannot be altered by
1129 quoting them.
1130 Arithmetic Evaluation.
1132 The shell performs arithmetic evaluation for arithmetic substitution,
1133 to evaluate an arithmetic command, to evaluate an indexed array sub‐
1134 script, and to evaluate arguments to the built-in commands shift and
1135 let. Evaluations are performed using double precision floating point
1136 arithmetic or long double precision floating point for systems that
1137 provide this data type. Floating point constants follow the ANSI-C
1138 programming language floating point conventions. The floating point
1139 constants Nan and Inf can be use to represent "not a number" and infin‐
1140 ity respectively. Integer constants follow the ANSI-C programming lan‐
1141 guage integer constant conventions although only single byte character
1142 constants are recognized and character casts are not recognized. In
1143 addition constants can be of the form [base#]n where base is a decimal
1144 number between two and sixty-four representing the arithmetic base and
1145 n is a number in that base. The digits above 9 are represented by the
1146 lower case letters, the upper case letters, @, and _ respectively. For
1147 bases less than or equal to 36, upper and lower case characters can be
1148 used interchangeably.
1149 An arithmetic expression uses the same syntax, precedence, and associa‐
1151 tivity of expression as the C language. All the C language operators
1152 that apply to floating point quantities can be used. In addition, the
1153 operator ** can be used for exponentiation. It has higher precedence
1154 than multiplication and is left associative. In addition, when the
1155 value of an arithmetic variable or sub-expression can be represented as
1156 a long integer, all C language integer arithmetic operations can be
1157 performed. Variables can be referenced by name within an arithmetic
1158 expression without using the parameter expansion syntax. When a vari‐
1159 able is referenced, its value is evaluated as an arithmetic expression.
1160 Any of the following math library functions that are in the C math
1162 library can be used within an arithmetic expression:
1163 abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh
1165 erf erfc exp exp2 expm1 fabs fdim finite floor fma fmax fmin fmod hypot
1166 ilogb int isfinite sinf isnan isnormal issubnormal issubordered iszero
1167 j0 j1 jn lgamma log log10 log2 logb nearbyint pow remainder rint round
1168 scanb signbit sin sinh sqrt tan tanh tgamma trunc y0 y1 yn In addition,
1169 arithmetic functions can be defined as shell functions with a variant
1170 of the function name syntax,
1171 function .sh.math.name ident ... { list ;}
1173 where name is the function name used in the arithmetic expres‐
1174 sion. If the calling argument corresponding to ident is the
1175 name of an array variable, then ident is a name reference to
1176 this array. Otherwise, ident is a reference to long double pre‐
1177 cision floating point variable containing the value from the
1178 caller. The value of .sh.value when the function returns is the
1179 value of this function. User defined functions can take up to 3
1180 arguments and override C math library functions.
1181 An internal representation of a variable as a double precision floating
1183 point can be specified with the -E [n], -F [n], or -X [n] option of the
1184 typeset special built-in command. The -E option causes the expansion
1185 of the value to be represented using scientific notation when it is
1186 expanded. The optional option argument n defines the number of signif‐
1187 icant figures. The -F option causes the expansion to be represented as
1188 a floating decimal number when it is expanded. The -X option cause the
1189 expansion to be represented using the %a format defined by ISO C-99.
1190 The optional option argument n defines the number of places after the
1191 decimal (or radix) point in this case.
1192 An internal integer representation of a variable can be specified with
1194 the -i [n] option of the typeset special built-in command. The
1195 optional option argument n specifies an arithmetic base to be used when
1196 expanding the variable. If you do not specify an arithmetic base, base
1197 10 will be used.
1198 Arithmetic evaluation is performed on the value of each assignment to a
1200 variable with the -E, -F, -X, or -i attribute. Assigning a floating
1201 point number to a variable whose type is an integer causes the frac‐
1202 tional part to be truncated.
1203 Inside an arithmetic expression, all integer and floating point vari‐
1205 ables can be following by .MIN, .MAX, or .DIG to give the maximum
1206 value, mininum value, or number of significant digits for variables of
1207 that type.
1208 Floating point variables can be also followed by .INT_MAX or .INT_MIN
1210 to give the largest or smallest integers represented by that type.
1211 Floating point variables can also be followed by .EPSILON to give the
1213 distance to the next floating point number of that type. Floating
1214 point variables can be followed by MAX_10_EXP to give the maximum base
1215 10 exponent that can be represented by that type.
1216 Inside an arithmetic expression, the following constants are recong‐
1218 nized and are of type typeset-lE.
1219 NaN Not a number. It is case insensitive.
1220 Inf Infinity. It is case insensitive.
1221 E
1222 PI
1223 1_PI 1.0/PI.
1224 2_PI 2.0/PI.
1225 PI_2 PI/2.0
1226 PI_4 PI/4.0.
1227 SQRTPI sqrt(PI).
1228 SQRT2 sqrt(2.0).
1229 SQRT1_2
1230 sqrt(1./2.)
1231 LOGE log(E)
1232 LOG10E log10(E)
1233 LN2 log(2.0)
1234 LOG2E log2(E)
1235 Array Sorting.
1237 The -s option of the set built-in command can be used to sort its argu‐
1238 ments or to sort indexed arrays, indexed arrays of compound variables,
1239 and indexed arrays of types (see "Type Variables" section below). By
1240 default the sort order is defined by the current locale. For compound
1241 variables and for types, the -K option for set can be followed by a
1242 comma separated list of sub-fields to sort on. Each field can be fol‐
1243 lowed by a : and the letter n for numerical sorting and/or r for
1244 reverse sorting. For an plain indexed array the -K option can be fol‐
1245 lowed by :n and :r for numerical or reverse sorting.
1246 Prompting.
1248 When used interactively, the shell prompts with the value of PS1 after
1249 expanding it for parameter expansion, command substitution, and arith‐
1250 metic substitution, before reading a command. In addition, each single
1251 ! in the prompt is replaced by the command number. A !! is required
1252 to place ! in the prompt. If at any time a new-line is typed and fur‐
1253 ther input is needed to complete a command, then the secondary prompt
1254 (i.e., the value of PS2) is issued.
1255 Conditional Expressions.
1257 A conditional expression is used with the [[ compound command to test
1258 attributes of files and to compare strings. Field splitting and file
1259 name generation are not performed on the words between [[ and ]]. Each
1260 expression can be constructed from one or more of the following unary
1261 or binary expressions:
1262 string True, if string is not null.
1263 -a file
1264 Same as -e below. This is obsolete.
1265 -b file
1266 True, if file exists and is a block special file.
1267 -c file
1268 True, if file exists and is a character special file.
1269 -d file
1270 True, if file exists and is a directory.
1271 -e file
1272 True, if file exists.
1273 -f file
1274 True, if file exists and is an ordinary file.
1275 -g file
1276 True, if file exists and it has its setgid bit set.
1277 -k file
1278 True, if file exists and it has its sticky bit set.
1279 -n string
1280 True, if length of string is non-zero.
1281 -o ?option
1282 True, if option named option is a valid option name.
1283 -o option
1284 True, if option named option is on.
1285 -p file
1286 True, if file exists and is a fifo special file or a pipe.
1287 -r file
1288 True, if file exists and is readable by current process.
1289 -s file
1290 True, if file exists and has size greater than zero.
1291 -t fildes
1292 True, if file descriptor number fildes is open and associated
1293 with a terminal device.
1294 -u file
1295 True, if file exists and it has its setuid bit set.
1296 -v name
1297 True, if variable name is a valid variable name and is set.
1298 -w file
1299 True, if file exists and is writable by current process.
1300 -x file
1301 True, if file exists and is executable by current process. If
1302 file exists and is a directory, then true if the current process
1303 has permission to search in the directory.
1304 -z string
1305 True, if length of string is zero.
1306 -L file
1307 True, if file exists and is a symbolic link.
1308 -h file
1309 True, if file exists and is a symbolic link.
1310 -N file
1311 True, if file exists and the modification time is greater than
1312 the last access time.
1313 -O file
1314 True, if file exists and is owned by the effective user id of
1315 this process.
1316 -G file
1317 True, if file exists and its group matches the effective group
1318 id of this process.
1319 -R name
1320 True if variable name is a name reference.
1321 -S file
1322 True, if file exists and is a socket.
1323 file1 -nt file2
1324 True, if file1 exists and file2 does not, or file1 is newer than
1325 file2.
1326 file1 -ot file2
1327 True, if file2 exists and file1 does not, or file1 is older than
1328 file2.
1329 file1 -ef file2
1330 True, if file1 and file2 exist and refer to the same file.
1331 string == pattern
1332 True, if string matches pattern. Any part of pattern can be
1333 quoted to cause it to be matched as a string. With a successful
1334 match to a pattern, the .sh.match array variable will contain
1335 the match and sub-pattern matches.
1336 string = pattern
1337 Same as == above, but is obsolete.
1338 string != pattern
1339 True, if string does not match pattern. When the string matches
1340 the pattern the .sh.match array variable will contain the match
1341 and sub-pattern matches.
1342 string =∼ ere
1343 True if string matches the pattern ∼(E)ere where ere is an
1344 extended regular expression.
1345 string1 < string2
1346 True, if string1 comes before string2 based on the current
1347 locale.
1348 string1 > string2
1349 True, if string1 comes after string2 based on the current
1350 locale.
1351 The following obsolete arithmetic comparisons are also permitted:
1352 exp1 -eq exp2
1353 True, if exp1 is equal to exp2.
1354 exp1 -ne exp2
1355 True, if exp1 is not equal to exp2.
1356 exp1 -lt exp2
1357 True, if exp1 is less than exp2.
1358 exp1 -gt exp2
1359 True, if exp1 is greater than exp2.
1360 exp1 -le exp2
1361 True, if exp1 is less than or equal to exp2.
1362 exp1 -ge exp2
1363 True, if exp1 is greater than or equal to exp2.
1364 In each of the above expressions, if file is of the form /dev/fd/n,
1366 where n is an integer, then the test is applied to the open file whose
1367 descriptor number is n.
1368 A compound expression can be constructed from these primitives by using
1370 any of the following, listed in decreasing order of precedence.
1371 (expression)
1372 True, if expression is true. Used to group expressions.
1373 ! expression
1374 True if expression is false.
1375 expression1 && expression2
1376 True, if expression1 and expression2 are both true.
1377 expression1 ⎪⎪ expression2
1378 True, if either expression1 or expression2 is true.
1379 Input/Output.
1381 Before a command is executed, its input and output may be redirected
1382 using a special notation interpreted by the shell. The following may
1383 appear anywhere in a simple-command or may precede or follow a command
1384 and are not passed on to the invoked command. Command substitution,
1385 parameter expansion, and arithmetic substitution occur before word or
1386 digit is used except as noted below. File name generation occurs only
1387 if the shell is interactive and the pattern matches a single file.
1388 Field splitting is not performed.
1389 In each of the following redirections, if file is of the form
1391 /dev/sctp/host/port, /dev/tcp/host/port, or /dev/udp/host/port, where
1392 host is a hostname or host address, and port is a service given by name
1393 or an integer port number, then the redirection attempts to make a tcp,
1394 sctp or udp connection to the corresponding socket.
1395 No intervening space is allowed between the characters of redirection
1397 operators.
1398 <word Use file word as standard input (file descriptor 0).
1400 >word Use file word as standard output (file descriptor 1). If
1402 the file does not exist then it is created. If the file
1403 exists, and the noclobber option is on, this causes an
1404 error; otherwise, it is truncated to zero length.
1405 >|word Same as >, except that it overrides the noclobber option.
1407 >;word Write output to a temporary file. If the command com‐
1409 pletes successfully rename it to word, otherwise, delete
1410 the temporary file. >;word cannot be used with the
1411 exec(2). built-in.
1412 >>word Use file word as standard output. If the file exists,
1414 then output is appended to it (by first seeking to the
1415 end-of-file); otherwise, the file is created.
1416 <>word Open file word for reading and writing as standard input.
1418 <>;word The same as <>word except that if the command completes
1420 successfully, word is truncated to the offset at command
1421 completion. <>;word cannot be used with the exec(2).
1422 built-in.
1423 <<[-]word The shell input is read up to a line that is the same as
1425 word after any quoting has been removed, or to an end-of-
1426 file. No parameter substitution, command substitution,
1427 arithmetic substitution or file name generation is per‐
1428 formed on word. The resulting document, called a here-
1429 document, becomes the standard input. If any character
1430 of word is quoted, then no interpretation is placed upon
1431 the characters of the document; otherwise, parameter
1432 expansion, command substitution, and arithmetic substitu‐
1433 tion occur, \new-line is ignored, and \ must be used to
1434 quote the characters \, $, `. If - is appended to <<,
1435 then all leading tabs are stripped from word and from the
1436 document. If # is appended to <<, then leading spaces
1437 and tabs will be stripped off the first line of the docu‐
1438 ment and up to an equivalent indentation will be stripped
1439 from the remaining lines and from word. A tab stop is
1440 assumed to occur at every 8 columns for the purposes of
1441 determining the indentation.
1442 <<<word A short form of here document in which word becomes the
1444 contents of the here-document after any parameter expan‐
1445 sion, command substitution, and arithmetic substitution
1446 occur.
1447 <&digit The standard input is duplicated from file descriptor
1449 digit (see dup(2)). Similarly for the standard output
1450 using >&digit.
1451 <&digit- The file descriptor given by digit is moved to standard
1453 input. Similarly for the standard output using >&digit-.
1454 <&- The standard input is closed. Similarly for the standard
1456 output using >&-.
1457 <&p The input from the co-process is moved to standard input.
1459 >&p The output to the co-process is moved to standard output.
1461 <#((expr)) Evaluate arithmetic expression expr and position file
1463 descriptor 0 to the resulting value bytes from the start
1464 of the file. The variables CUR and EOF evaluate to the
1465 current offset and end-of-file offset respectively when
1466 evaluating expr.
1467 >#((offset)) The same as <# except applies to file descriptor 1.
1469 <#pattern Seeks forward to the beginning of the next line contain‐
1471 ing pattern.
1472 <##pattern The same as <# except that the portion of the file that
1474 is skipped is copied to standard output.
1475 If one of the above is preceded by a digit, with no intervening space,
1477 then the file descriptor number referred to is that specified by the
1478 digit (instead of the default 0 or 1). If one of the above, other than
1479 >&- and the ># and <# forms, is preceded by {varname} with no interven‐
1480 ing space, then a file descriptor number > 10 will be selected by the
1481 shell and stored in the variable varname. If >&- or the any of the >#
1482 and <# forms is preceded by {varname} the value of varname defines the
1483 file descriptor to close or position. For example:
1484 ... 2>&1
1486 means file descriptor 2 is to be opened for writing as a duplicate of
1488 file descriptor 1 and
1489 exec {n}<file
1491 means open file named file for reading and store the file descriptor
1493 number in variable n.
1494 The order in which redirections are specified is significant. The
1496 shell evaluates each redirection in terms of the (file descriptor,
1497 file) association at the time of evaluation. For example:
1498 ... 1>fname 2>&1
1500 first associates file descriptor 1 with file fname. It then associates
1502 file descriptor 2 with the file associated with file descriptor 1 (i.e.
1503 fname). If the order of redirections were reversed, file descriptor 2
1504 would be associated with the terminal (assuming file descriptor 1 had
1505 been) and then file descriptor 1 would be associated with file fname.
1506 If a command is followed by & and job control is not active, then the
1508 default standard input for the command is the empty file /dev/null.
1509 Otherwise, the environment for the execution of a command contains the
1510 file descriptors of the invoking shell as modified by input/output
1511 specifications.
1512 Environment.
1514 The environment (see environ(7)) is a list of name-value pairs that is
1515 passed to an executed program in the same way as a normal argument
1516 list. The names must be identifiers and the values are character
1517 strings. The shell interacts with the environment in several ways. On
1518 invocation, the shell scans the environment and creates a variable for
1519 each name found, giving it the corresponding value and attributes and
1520 marking it export. Executed commands inherit the environment. If the
1521 user modifies the values of these variables or creates new ones, using
1522 the export or typeset -x commands, they become part of the environment.
1523 The environment seen by any executed command is thus composed of any
1524 name-value pairs originally inherited by the shell, whose values may be
1525 modified by the current shell, plus any additions which must be noted
1526 in export or typeset -x commands.
1527 The environment for any simple-command or function may be augmented by
1529 prefixing it with one or more variable assignments. A variable assign‐
1530 ment argument is a word of the form identifier=value. Thus:
1531 TERM=450 cmd args and
1533 (export TERM; TERM=450; cmd args)
1534 are equivalent (as far as the above execution of cmd is concerned
1536 except for special built-in commands listed below - those that are pre‐
1537 ceded with a dagger).
1538 If the obsolete -k option is set, all variable assignment arguments are
1540 placed in the environment, even if they occur after the command name.
1541 The following first prints a=b c and then c:
1542 echo a=b c
1544 set -k
1545 echo a=b c
1546 This feature is intended for use with scripts written for early ver‐
1547 sions of the shell and its use in new scripts is strongly discouraged.
1548 It is likely to disappear someday.
1549 Functions.
1551 For historical reasons, there are two ways to define functions, the
1552 name() syntax and the function name syntax, described in the Commands
1553 section above. Shell functions are read in and stored internally.
1554 Alias names are resolved when the function is read. Functions are exe‐
1555 cuted like commands with the arguments passed as positional parameters.
1556 (See Execution below.)
1557 Functions defined by the function name syntax and called by name exe‐
1559 cute in the same process as the caller and share all files and present
1560 working directory with the caller. Traps caught by the caller are
1561 reset to their default action inside the function. A trap condition
1562 that is not caught or ignored by the function causes the function to
1563 terminate and the condition to be passed on to the caller. A trap on
1564 EXIT set inside a function is executed in the environment of the caller
1565 after the function completes. Ordinarily, variables are shared between
1566 the calling program and the function. However, the typeset special
1567 built-in command used within a function defines local variables whose
1568 scope includes the current function. They can be passed to functions
1569 that they call in the variable assignment list that precedes the call
1570 or as arguments passed as name references. Errors within functions
1571 return control to the caller.
1572 Functions defined with the name() syntax and functions defined with the
1574 function name syntax that are invoked with the . special built-in are
1575 executed in the caller's environment and share all variables and traps
1576 with the caller. Errors within these function executions cause the
1577 script that contains them to abort.
1578 The special built-in command return is used to return from function
1580 calls.
1581 Function names can be listed with the -f or +f option of the typeset
1583 special built-in command. The text of functions, when available, will
1584 also be listed with -f. Functions can be undefined with the -f option
1585 of the unset special built-in command.
1586 Ordinarily, functions are unset when the shell executes a shell script.
1588 Functions that need to be defined across separate invocations of the
1589 shell should be placed in a directory and the FPATH variable should
1590 contain the name of this directory. They may also be specified in the
1591 ENV file.
1592 Discipline Functions.
1594 Each variable can have zero or more discipline functions associated
1595 with it. The shell initially understands the discipline names get,
1596 set, append, and unset but can be added when defining new types. On
1597 most systems others can be added at run time via the C programming
1598 interface extension provided by the builtin built-in utility. If the
1599 get discipline is defined for a variable, it is invoked whenever the
1600 given variable is referenced. If the variable .sh.value is assigned a
1601 value inside the discipline function, the referenced variable will
1602 evaluate to this value instead. If the set discipline is defined for a
1603 variable, it is invoked whenever the given variable is assigned a
1604 value. If the append discipline is defined for a variable, it is
1605 invoked whenever a value is appended to the given variable. The vari‐
1606 able .sh.value is given the value of the variable before invoking the
1607 discipline, and the variable will be assigned the value of .sh.value
1608 after the discipline completes. If .sh.value is unset inside the dis‐
1609 cipline, then that value is unchanged. If the unset discipline is
1610 defined for a variable, it is invoked whenever the given variable is
1611 unset. The variable will not be unset unless it is unset explicitly
1612 from within this discipline function.
1613 The variable .sh.name contains the name of the variable for which the
1615 discipline function is called, .sh.subscript is the subscript of the
1616 variable, and .sh.value will contain the value being assigned inside
1617 the set discipline function. The variable _ is a reference to the
1618 variable including the subscript if any. For the set discipline,
1619 changing .sh.value will change the value that gets assigned. Finally,
1620 the expansion ${var.name}, when name is the name of a discipline, and
1621 there is no variable of this name, is equivalent to the command substi‐
1622 tution ${ var.name;}.
1623 Name Spaces.
1626 Commands and functions that are executed as part of the list of a
1627 namespace command that modify variables or create new ones, create a
1628 new variable whose name is the name of the name space as given by iden‐
1629 tifier preceded by .. When a variable whose name is name is refer‐
1630 enced, it is first searched for using .identifier.name. Similarly, a
1631 function defined by a command in the namespace list is created using
1632 the name space name preceded by a ..
1633 When the list of a namespace command contains a namespace command, the
1635 names of variables and functions that are created consist of the vari‐
1636 able or function name preceded by the list of identifiers each preceded
1637 by ..
1638 Outside of a name space, a variable or function created inside a name
1640 space can be referenced by preceding it with the name space name.
1641 By default, variables staring with .sh are in the sh name space.
1643 Type Variables.
1646 Typed variables provide a way to create data structure and objects. A
1647 type can be defined either by a shared library, by the enum built-in
1648 command described below, or by using the new -T option of the typeset
1649 built-in command. With the -T option of typeset, the type name, speci‐
1650 fied as an option argument to -T, is set with a compound variable
1651 assignment that defines the type. Function definitions can appear
1652 inside the compound variable assignment and these become discipline
1653 functions for this type and can be invoked or redefined by each
1654 instance of the type. The function name create is treated specially.
1655 It is invoked for each instance of the type that is created but is not
1656 inherited and cannot be redefined for each instance.
1657 When a type is defined a special built-in command of that name is
1659 added. These built-ins are declaration commands and follow the same
1660 expansion rules as all the special built-in commands defined below that
1661 are preceded by ††. These commands can subsequently be used inside
1662 further type definitions. The man page for these commands can be gen‐
1663 erated by using the --man option or any of the other -- options
1664 described with getopts. The -r, -a, -A, -h, and -S options of typeset
1665 are permitted with each of these new built-ins.
1666 An instance of a type is created by invoking the type name followed by
1668 one or more instance names. Each instance of the type is initialized
1669 with a copy of the sub-variables except for sub-variables that are
1670 defined with the -S option. Variables defined with the -S are shared
1671 by all instances of the type. Each instance can change the value of
1672 any sub-variable and can also define new discipline functions of the
1673 same names as those defined by the type definition as well as any stan‐
1674 dard discipline names. No additional sub-variables can be defined for
1675 any instance.
1676 When defining a type, if the value of a sub-variable is not set and the
1678 -r attribute is specified, it causes the sub-variable to be a required
1679 sub-variable. Whenever an instance of a type is created, all required
1680 sub-variables must be specified. These sub-variables become readonly
1681 in each instance.
1682 When unset is invoked on a sub-variable within a type, and the -r
1684 attribute has not been specified for this field, the value is reset to
1685 the default value associative with the type. Invoking unset on a type
1686 instance not contained within another type deletes all sub-variables
1687 and the variable itself.
1688 A type definition can be derived from another type definition by defin‐
1690 ing the first sub-variable name as _ and defining its type as the base
1691 type. Any remaining definitions will be additions and modifications
1692 that apply to the new type. If the new type name is the same as that
1693 of the base type, the type will be replaced and the original type will
1694 no longer be accessible.
1695 The typeset command with the -T and no option argument or operands will
1697 write all the type definitions to standard output in a form that can be
1698 read in to create all the types.
1699 Jobs.
1701 If the monitor option of the set command is turned on, an interactive
1702 shell associates a job with each pipeline. It keeps a table of current
1703 jobs, printed by the jobs command, and assigns them small integer num‐
1704 bers. When a job is started asynchronously with &, the shell prints a
1705 line which looks like:
1706 [1] 1234
1708 indicating that the job which was started asynchronously was job number
1710 1 and had one (top-level) process, whose process id was 1234.
1711 This paragraph and the next require features that are not in all ver‐
1713 sions of UNIX and may not apply. If you are running a job and wish to
1714 do something else you may hit the key ^Z (control-Z) which sends a STOP
1715 signal to the current job. The shell will then normally indicate that
1716 the job has been `Stopped', and print another prompt. You can then
1717 manipulate the state of this job, putting it in the background with the
1718 bg command, or run some other commands and then eventually bring the
1719 job back into the foreground with the foreground command fg. A ^Z
1720 takes effect immediately and is like an interrupt in that pending out‐
1721 put and unread input are discarded when it is typed.
1722 A job being run in the background will stop if it tries to read from
1724 the terminal. Background jobs are normally allowed to produce output,
1725 but this can be disabled by giving the command stty tostop. If you set
1726 this tty option, then background jobs will stop when they try to pro‐
1727 duce output like they do when they try to read input.
1728 A job pool is a collection of jobs started with list & associated with
1730 a name.
1731 There are several ways to refer to jobs in the shell. A job can be
1733 referred to by the process id of any process of the job or by one of
1734 the following:
1735 %number
1736 The job with the given number.
1737 pool All the jobs in the job pool named by pool.
1738 pool.number
1739 The job number number in the job pool named by pool.
1740 %string
1741 Any job whose command line begins with string.
1742 %?string
1743 Any job whose command line contains string.
1744 %% Current job.
1745 %+ Equivalent to %%.
1746 %- Previous job. In addition, unless noted otherwise, wherever a
1747 job can be specified, the name of a background job pool can be
1748 used to represent all the jobs in that pool.
1749 The shell learns immediately whenever a process changes state. It nor‐
1751 mally informs you whenever a job becomes blocked so that no further
1752 progress is possible, but only just before it prints a prompt. This is
1753 done so that it does not otherwise disturb your work. The notify
1754 option of the set command causes the shell to print these job change
1755 messages as soon as they occur.
1756 When the monitor option is on, each background job that completes trig‐
1758 gers any trap set for CHLD.
1759 When you try to leave the shell while jobs are running or stopped, you
1761 will be warned that `You have stopped(running) jobs.' You may use the
1762 jobs command to see what they are. If you immediately try to exit
1763 again, the shell will not warn you a second time, and the stopped jobs
1764 will be terminated. When a login shell receives a HUP signal, it sends
1765 a HUP signal to each job that has not been disowned with the disown
1766 built-in command described below.
1767 Signals.
1769 The INT and QUIT signals for an invoked command are ignored if the com‐
1770 mand is followed by & and the monitor option is active. Otherwise,
1771 signals have the values inherited by the shell from its parent (but see
1772 also the trap built-in command below).
1773 Execution.
1775 Each time a command is read, the above substitutions are carried out.
1776 If the command name matches one of the Special Built-in Commands listed
1777 below, it is executed within the current shell process. Next, the com‐
1778 mand name is checked to see if it matches a user defined function. If
1779 it does, the positional parameters are saved and then reset to the
1780 arguments of the function call. A function is also executed in the
1781 current shell process. When the function completes or issues a return,
1782 the positional parameter list is restored. For functions defined with
1783 the function name syntax, any trap set on EXIT within the function is
1784 executed. The exit value of a function is the value of the last com‐
1785 mand executed. If a command name is not a special built-in command or
1786 a user defined function, but it is one of the built-in commands listed
1787 below, it is executed in the current shell process.
1788 The shell variables PATH followed by the variable FPATH defines the
1790 list of directories to search for the command name. Alternative direc‐
1791 tory names are separated by a colon (:). The default path is equal to
1792 getconf PATH output. The current directory can be specified by two or
1793 more adjacent colons, or by a colon at the beginning or end of the path
1794 list. If the command name contains a /, then the search path is not
1795 used. Otherwise, each directory in the list of directories defined by
1796 PATH and FPATH is checked in order. If the directory being searched is
1797 contained in FPATH and contains a file whose name matches the command
1798 being searched, then this file is loaded into the current shell envi‐
1799 ronment as if it were the argument to the . command except that only
1800 preset aliases are expanded, and a function of the given name is exe‐
1801 cuted as described above.
1802 If this directory is not in FPATH the shell first determines whether
1804 there is a built-in version of a command corresponding to a given path‐
1805 name and if so it is invoked in the current process. If no built-in is
1806 found, the shell checks for a file named .paths in this directory. If
1807 found and there is a line of the form FPATH=path where path names an
1808 existing directory then that directory is searched immediately after
1809 the current directory as if it were found in the FPATH variable. If
1810 path does not begin with /, it is checked for relative to the directory
1811 being searched.
1812 The .paths file is then checked for a line of the form PLUGIN_LIB=lib‐
1814 name [ : libname ] ... . Each library named by libname will be
1815 searched for as if it were an option argument to builtin -f, and if it
1816 contains a built-in of the specified name this will be executed instead
1817 of a command by this name. Any built-in loaded from a library found
1818 this way will be associated with the directory containing the .paths
1819 file so it will only execute if not found in an earlier directory.
1820 Finally, the directory will be checked for a file of the given name.
1822 If the file has execute permission but is not an a.out file, it is
1823 assumed to be a file containing shell commands. A separate shell is
1824 spawned to read it. All non-exported variables are removed in this
1825 case. If the shell command file doesn't have read permission, or if
1826 the setuid and/or setgid bits are set on the file, then the shell exe‐
1827 cutes an agent whose job it is to set up the permissions and execute
1828 the shell with the shell command file passed down as an open file. If
1829 the .paths contains a line of the form name=value in the first or sec‐
1830 ond line, then the environment variable name is modified by prepending
1831 the directory specified by value to the directory list. If value is
1832 not an absolute directory, then it specifies a directory relative to
1833 the directory that the executable was found. If the environment vari‐
1834 able name does not already exist it will be added to the environment
1835 list for the specified command. A parenthesized command is executed in
1836 a sub-shell without removing non-exported variables.
1837 Command Re-entry.
1839 The text of the last HISTSIZE (default 512) commands entered from a
1840 terminal device is saved in a history file. The file $HOME/.sh_history
1841 is used if the HISTFILE variable is not set or if the file it names is
1842 not writable. A shell can access the commands of all interactive
1843 shells which use the same named HISTFILE. The built-in command hist is
1844 used to list or edit a portion of this file. The portion of the file
1845 to be edited or listed can be selected by number or by giving the first
1846 character or characters of the command. A single command or range of
1847 commands can be specified. If you do not specify an editor program as
1848 an argument to hist then the value of the variable HISTEDIT is used.
1849 If HISTEDIT is unset, the obsolete variable FCEDIT is used. If FCEDIT
1850 is not defined, then /bin/ed is used. The edited command(s) is printed
1851 and re-executed upon leaving the editor unless you quit without writ‐
1852 ing. The -s option (and in obsolete versions, the editor name -) is
1853 used to skip the editing phase and to re-execute the command. In this
1854 case a substitution parameter of the form old=new can be used to modify
1855 the command before execution. For example, with the preset alias r,
1856 which is aliased to ′hist -s′, typing `r bad=good c' will re-execute
1857 the most recent command which starts with the letter c, replacing the
1858 first occurrence of the string bad with the string good.
1859 In-line Editing Options.
1861 Normally, each command line entered from a terminal device is simply
1862 typed followed by a new-line (`RETURN' or `LINE FEED'). If either the
1863 emacs, gmacs, or vi option is active, the user can edit the command
1864 line. To be in either of these edit modes set the corresponding
1865 option. An editing option is automatically selected each time the VIS‐
1866 UAL or EDITOR variable is assigned a value ending in either of these
1867 option names.
1868 The editing features require that the user's terminal accept `RETURN'
1870 as carriage return without line feed and that a space (` ') must over‐
1871 write the current character on the screen.
1872 Unless the multiline option is on, the editing modes implement a con‐
1874 cept where the user is looking through a window at the current line.
1875 The window width is the value of COLUMNS if it is defined, otherwise
1876 80. If the window width is too small to display the prompt and leave
1877 at least 8 columns to enter input, the prompt is truncated from the
1878 left. If the line is longer than the window width minus two, a mark is
1879 displayed at the end of the window to notify the user. As the cursor
1880 moves and reaches the window boundaries the window will be centered
1881 about the cursor. The mark is a > (<, *) if the line extends on the
1882 right (left, both) side(s) of the window.
1883 The search commands in each edit mode provide access to the history
1885 file. Only strings are matched, not patterns, although a leading ^ in
1886 the string restricts the match to begin at the first character in the
1887 line.
1888 Each of the edit modes has an operation to list the files or commands
1890 that match a partially entered word. When applied to the first word on
1891 the line, or the first word after a ;, ⎪, &, or (, and the word does
1892 not begin with ∼ or contain a /, the list of aliases, functions, and
1893 executable commands defined by the PATH variable that could match the
1894 partial word is displayed. Otherwise, the list of files that match the
1895 given word is displayed. If the partially entered word does not con‐
1896 tain any file expansion characters, a * is appended before generating
1897 these lists. After displaying the generated list, the input line is
1898 redrawn. These operations are called command name listing and file
1899 name listing, respectively. There are additional operations, referred
1900 to as command name completion and file name completion, which compute
1901 the list of matching commands or files, but instead of printing the
1902 list, replace the current word with a complete or partial match. For
1903 file name completion, if the match is unique, a / is appended if the
1904 file is a directory and a space is appended if the file is not a direc‐
1905 tory. Otherwise, the longest common prefix for all the matching files
1906 replaces the word. For command name completion, only the portion of
1907 the file names after the last / are used to find the longest command
1908 prefix. If only a single name matches this prefix, then the word is
1909 replaced with the command name followed by a space. When using a tab
1910 for completion that does not yield a unique match, a subsequent tab
1911 will provide a numbered list of matching alternatives. A specific
1912 selection can be made by entering the selection number followed by a
1913 tab.
1914 Key Bindings.
1916 The KEYBD trap can be used to intercept keys as they are typed and
1917 change the characters that are actually seen by the shell. This trap
1918 is executed after each character (or sequence of characters when the
1919 first character is ESC) is entered while reading from a terminal. The
1920 variable .sh.edchar contains the character or character sequence which
1921 generated the trap. Changing the value of .sh.edchar in the trap
1922 action causes the shell to behave as if the new value were entered from
1923 the keyboard rather than the original value.
1924 The variable .sh.edcol is set to the input column number of the cursor
1926 at the time of the input. The variable .sh.edmode is set to ESC when
1927 in vi insert mode (see below) and is null otherwise. By prepending
1928 ${.sh.editmode} to a value assigned to .sh.edchar it will cause the
1929 shell to change to control mode if it is not already in this mode.
1930 This trap is not invoked for characters entered as arguments to editing
1932 directives, or while reading input for a character search.
1933 Emacs Editing Mode.
1935 This mode is entered by enabling either the emacs or gmacs option. The
1936 only difference between these two modes is the way they handle ^T. To
1937 edit, the user moves the cursor to the point needing correction and
1938 then inserts or deletes characters or words as needed. All the editing
1939 commands are control characters or escape sequences. The notation for
1940 control characters is caret (^) followed by the character. For exam‐
1941 ple, ^F is the notation for control F. This is entered by depressing
1942 `f' while holding down the `CTRL' (control) key. The `SHIFT' key is
1943 not depressed. (The notation ^? indicates the DEL (delete) key.)
1944 The notation for escape sequences is M- followed by a character. For
1946 example, M-f (pronounced Meta f) is entered by depressing ESC (ascii
1947 033) followed by `f'. (M-F would be the notation for ESC followed by
1948 `SHIFT' (capital) `F'.)
1949 All edit commands operate from any place on the line (not just at the
1951 beginning). Neither the `RETURN' nor the `LINE FEED' key is entered
1952 after edit commands except when noted.
1953 ^F Move cursor forward (right) one character.
1955 M-[C Move cursor forward (right) one character.
1956 M-f Move cursor forward one word. (The emacs editor's idea of a
1957 word is a string of characters consisting of only letters,
1958 digits and underscores.)
1959 ^B Move cursor backward (left) one character.
1960 M-[D Move cursor backward (left) one character.
1961 M-b Move cursor backward one word.
1962 ^A Move cursor to start of line.
1963 M-[H Move cursor to start of line.
1964 ^E Move cursor to end of line.
1965 M-[Y Move cursor to end of line.
1966 ^]char Move cursor forward to character char on current line.
1967 M-^]char Move cursor backward to character char on current line.
1968 ^X^X Interchange the cursor and mark.
1969 erase (User defined erase character as defined by the stty(1) com‐
1970 mand, usually ^H or #.) Delete previous character.
1971 lnext (User defined literal next character as defined by the
1972 stty(1) command, or ^V if not defined.) Removes the next
1973 character's editing features (if any).
1974 ^D Delete current character.
1975 M-d Delete current word.
1976 M-^H (Meta-backspace) Delete previous word.
1977 M-h Delete previous word.
1978 M-^? (Meta-DEL) Delete previous word (if your interrupt character
1979 is ^? (DEL, the default) then this command will not work).
1980 ^T Transpose current character with previous character and
1981 advance the cursor in emacs mode. Transpose two previous
1982 characters in gmacs mode.
1983 ^C Capitalize current character.
1984 M-c Capitalize current word.
1985 M-l Change the current word to lower case.
1986 ^K Delete from the cursor to the end of the line. If preceded
1987 by a numerical parameter whose value is less than the current
1988 cursor position, then delete from given position up to the
1989 cursor. If preceded by a numerical parameter whose value is
1990 greater than the current cursor position, then delete from
1991 cursor up to given cursor position.
1992 ^W Kill from the cursor to the mark.
1993 M-p Push the region from the cursor to the mark on the stack.
1994 kill (User defined kill character as defined by the stty command,
1995 usually ^G or @.) Kill the entire current line. If two kill
1996 characters are entered in succession, all kill characters
1997 from then on cause a line feed (useful when using paper ter‐
1998 minals).
1999 ^Y Restore last item removed from line. (Yank item back to the
2000 line.)
2001 ^L Line feed and print current line.
2002 M-^L Clear the screen.
2003 ^@ (Null character) Set mark.
2004 M-space (Meta space) Set mark.
2005 ^J (New line) Execute the current line.
2006 ^M (Return) Execute the current line.
2007 eof End-of-file character, normally ^D, is processed as an End-
2008 of-file only if the current line is null.
2009 ^P Fetch previous command. Each time ^P is entered the previous
2010 command back in time is accessed. Moves back one line when
2011 not on the first line of a multi-line command.
2012 M-[A If the cursor is at the end of the line, it is equivalent to
2013 ^R with string set to the contents of the current line. Oth‐
2014 erwise, it is equivalent to ^P.
2015 M-< Fetch the least recent (oldest) history line.
2016 M-> Fetch the most recent (youngest) history line.
2017 ^N Fetch next command line. Each time ^N is entered the next
2018 command line forward in time is accessed.
2019 M-[B Equivalent to ^N.
2020 ^Rstring Reverse search history for a previous command line containing
2021 string. If a parameter of zero is given, the search is for‐
2022 ward. String is terminated by a `RETURN' or `NEW LINE'. If
2023 string is preceded by a ^, the matched line must begin with
2024 string. If string is omitted, then the next command line
2025 containing the most recent string is accessed. In this case
2026 a parameter of zero reverses the direction of the search.
2027 ^O Operate - Execute the current line and fetch the next line
2028 relative to current line from the history file.
2029 M-digits (Escape) Define numeric parameter, the digits are taken as a
2030 parameter to the next command. The commands that accept a
2031 parameter are ^F, ^B, erase, ^C, ^D, ^K, ^R, ^P, ^N, ^], M-.,
2032 M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l and M-^H.
2033 M-letter Soft-key - Your alias list is searched for an alias by the
2034 name _letter and if an alias of this name is defined, its
2035 value will be inserted on the input queue. The letter must
2036 not be one of the above meta-functions.
2037 M-[letter Soft-key - Your alias list is searched for an alias by the
2038 name __letter and if an alias of this name is defined, its
2039 value will be inserted on the input queue. This can be used
2040 to program function keys on many terminals.
2041 M-. The last word of the previous command is inserted on the
2042 line. If preceded by a numeric parameter, the value of this
2043 parameter determines which word to insert rather than the
2044 last word.
2045 M-_ Same as M-..
2046 M-* Attempt file name generation on the current word. An aster‐
2047 isk is appended if the word doesn't match any file or contain
2048 any special pattern characters.
2049 M-ESC Command or file name completion as described above.
2050 ^I tab Attempts command or file name completion as described above.
2051 If a partial completion occurs, repeating this will behave as
2052 if M-= were entered. If no match is found or entered after
2053 space, a tab is inserted.
2054 M-= If not preceded by a numeric parameter, it generates the list
2055 of matching commands or file names as described above. Oth‐
2056 erwise, the word under the cursor is replaced by the item
2057 corresponding to the value of the numeric parameter from the
2058 most recently generated command or file list. If the cursor
2059 is not on a word, it is inserted instead.
2060 ^U Multiply parameter of next command by 4.
2061 \ Escape next character. Editing characters, the user's erase,
2062 kill and interrupt (normally ^?) characters may be entered
2063 in a command line or in a search string if preceded by a \.
2064 The \ removes the next character's editing features (if any).
2065 M-^V Display version of the shell.
2066 M-# If the line does not begin with a #, a # is inserted at the
2067 beginning of the line and after each new-line, and the line
2068 is entered. This causes a comment to be inserted in the his‐
2069 tory file. If the line begins with a #, the # is deleted and
2070 one # after each new-line is also deleted.
2071 Vi Editing Mode.
2073 There are two typing modes. Initially, when you enter a command you
2074 are in the input mode. To edit, the user enters control mode by typing
2075 ESC (033) and moves the cursor to the point needing correction and then
2076 inserts or deletes characters or words as needed. Most control com‐
2077 mands accept an optional repeat count prior to the command.
2078 When in vi mode on most systems, canonical processing is initially
2080 enabled and the command will be echoed again if the speed is 1200 baud
2081 or greater and it contains any control characters or less than one sec‐
2082 ond has elapsed since the prompt was printed. The ESC character termi‐
2083 nates canonical processing for the remainder of the command and the
2084 user can then modify the command line. This scheme has the advantages
2085 of canonical processing with the type-ahead echoing of raw mode.
2086 If the option viraw is also set, the terminal will always have canoni‐
2088 cal processing disabled. This mode is implicit for systems that do not
2089 support two alternate end of line delimiters, and may be helpful for
2090 certain terminals.
2091 Input Edit Commands
2093 By default the editor is in input mode.
2094 erase (User defined erase character as defined by the stty
2095 command, usually ^H or #.) Delete previous character.
2096 ^W Delete the previous blank separated word.
2097 eof As the first character of the line causes the shell to
2098 terminate unless the ignoreeof option is set. Other‐
2099 wise this character is ignored.
2100 lnext (User defined literal next character as defined by the
2101 stty(1) or ^V if not defined.) Removes the next char‐
2102 acter's editing features (if any).
2103 \ Escape the next erase or kill character.
2104 ^I tab Attempts command or file name completion as described
2105 above and returns to input mode. If a partial comple‐
2106 tion occurs, repeating this will behave as if = were
2107 entered from control mode. If no match is found or
2108 entered after space, a tab is inserted.
2109 Motion Edit Commands
2110 These commands will move the cursor.
2111 [count]l Cursor forward (right) one character.
2112 [count][C Cursor forward (right) one character.
2113 [count]w Cursor forward one alpha-numeric word.
2114 [count]W Cursor to the beginning of the next word that follows
2115 a blank.
2116 [count]e Cursor to end of word.
2117 [count]E Cursor to end of the current blank delimited word.
2118 [count]h Cursor backward (left) one character.
2119 [count][D Cursor backward (left) one character.
2120 [count]b Cursor backward one word.
2121 [count]B Cursor to preceding blank separated word.
2122 [count]⎪ Cursor to column count.
2123 [count]fc Find the next character c in the current line.
2124 [count]Fc Find the previous character c in the current line.
2125 [count]tc Equivalent to f followed by h.
2126 [count]Tc Equivalent to F followed by l.
2127 [count]; Repeats count times, the last single character find
2128 command, f, F, t, or T.
2129 [count], Reverses the last single character find command count
2130 times.
2131 0 Cursor to start of line.
2132 ^ Cursor to start of line.
2133 [H Cursor to first non-blank character in line.
2134 $ Cursor to end of line.
2135 [Y Cursor to end of line.
2136 % Moves to balancing (, ), {, }, [, or ]. If cursor is
2137 not on one of the above characters, the remainder of
2138 the line is searched for the first occurrence of one
2139 of the above characters first.
2140 Search Edit Commands
2141 These commands access your command history.
2142 [count]k Fetch previous command. Each time k is entered the
2143 previous command back in time is accessed.
2144 [count]- Equivalent to k.
2145 [count][A If cursor is at the end of the line it is equivalent
2146 to / with string^set to the contents of the current
2147 line. Otherwise, it is equivalent to k.
2148 [count]j Fetch next command. Each time j is entered the next
2149 command forward in time is accessed.
2150 [count]+ Equivalent to j.
2151 [count][B Equivalent to j.
2152 [count]G The command number count is fetched. The default is
2153 the least recent history command.
2154 /string Search backward through history for a previous command
2155 containing string. String is terminated by a `RETURN'
2156 or `NEW LINE'. If string is preceded by a ^, the
2157 matched line must begin with string. If string is
2158 null, the previous string will be used.
2159 ?string Same as / except that search will be in the forward
2160 direction.
2161 n Search for next match of the last pattern to / or ?
2162 commands.
2163 N Search for next match of the last pattern to / or ?,
2164 but in reverse direction.
2165 Text Modification Edit Commands
2166 These commands will modify the line.
2167 a Enter input mode and enter text after the current
2168 character.
2169 A Append text to the end of the line. Equivalent to $a.
2170 [count]cmotion
2171 c[count]motion
2172 Delete current character through the character that
2173 motion would move the cursor to and enter input mode.
2174 If motion is c, the entire line will be deleted and
2175 input mode entered.
2176 C Delete the current character through the end of line
2177 and enter input mode. Equivalent to c$.
2178 S Equivalent to cc.
2179 [count]s Replace characters under the cursor in input mode.
2180 D Delete the current character through the end of line.
2181 Equivalent to d$.
2182 [count]dmotion
2183 d[count]motion
2184 Delete current character through the character that
2185 motion would move to. If motion is d , the entire
2186 line will be deleted.
2187 i Enter input mode and insert text before the current
2188 character.
2189 I Insert text before the beginning of the line. Equiva‐
2190 lent to 0i.
2191 [count]P Place the previous text modification before the cur‐
2192 sor.
2193 [count]p Place the previous text modification after the cursor.
2194 R Enter input mode and replace characters on the screen
2195 with characters you type overlay fashion.
2196 [count]rc Replace the count character(s) starting at the current
2197 cursor position with c, and advance the cursor.
2198 [count]x Delete current character.
2199 [count]X Delete preceding character.
2200 [count]. Repeat the previous text modification command.
2201 [count]∼ Invert the case of the count character(s) starting at
2202 the current cursor position and advance the cursor.
2203 [count]_ Causes the count word of the previous command to be
2204 appended and input mode entered. The last word is
2205 used if count is omitted.
2206 * Causes an * to be appended to the current word and
2207 file name generation attempted. If no match is found,
2208 it rings the bell. Otherwise, the word is replaced by
2209 the matching pattern and input mode is entered.
2210 \ Command or file name completion as described above.
2211 Other Edit Commands
2212 Miscellaneous commands.
2213 [count]ymotion
2214 y[count]motion
2215 Yank current character through character that motion
2216 would move the cursor to and puts them into the delete
2217 buffer. The text and cursor are unchanged.
2218 yy Yanks the entire line.
2219 Y Yanks from current position to end of line. Equiva‐
2220 lent to y$.
2221 u Undo the last text modifying command.
2222 U Undo all the text modifying commands performed on the
2223 line.
2224 [count]v Returns the command hist -e ${VISUAL:-${EDITOR:-vi}}
2225 count in the input buffer. If count is omitted, then
2226 the current line is used.
2227 ^L Line feed and print current line. Has effect only in
2228 control mode.
2229 ^J (New line) Execute the current line, regardless of
2230 mode.
2231 ^M (Return) Execute the current line, regardless of mode.
2232 # If the first character of the command is a #, then
2233 this command deletes this # and each # that follows a
2234 newline. Otherwise, sends the line after inserting a
2235 # in front of each line in the command. Useful for
2236 causing the current line to be inserted in the history
2237 as a comment and uncommenting previously commented
2238 commands in the history file.
2239 [count]= If count is not specified, it generates the list of
2240 matching commands or file names as described above.
2241 Otherwise, the word under the cursor is replaced by
2242 the count item from the most recently generated com‐
2243 mand or file list. If the cursor is not on a word, it
2244 is inserted instead.
2245 @letter Your alias list is searched for an alias by the name
2246 _letter and if an alias of this name is defined, its
2247 value will be inserted on the input queue for process‐
2248 ing.
2249 ^V Display version of the shell.
2250 Programmable Completion.
2252 By default, hitting the tab key causes the current word to be matched
2253 against files starting with the characters you typed and adding as many
2254 characters that provide a unique match. If the matching prefix is not
2255 unique hitting tab again will output a numbered list with the choices
2256 and entering number tab will replace the current word with that selec‐
2257 tion.
2258 Programmable completion allows you to control how words are expanded
2260 when you enter the tab key for one or more specified commands. The
2261 complete built-in command allows you to specify how to complete the
2262 current word of the specified command.
2263 Built-in Commands.
2265 The following simple-commands are executed in the shell process.
2266 Input/Output redirection is permitted. Unless otherwise indicated, the
2267 output is written on file descriptor 1 and the exit status, when there
2268 is no syntax error, is zero. Except for :, true, false, echo, newgrp,
2269 and login, all built-in commands accept -- to indicate end of options.
2270 They also interpret the option --man as a request to display the man
2271 page onto standard error and -? as a help request which prints a usage
2272 message on standard error. Commands that are preceded by one or two †
2273 symbols are special built-in commands and are treated specially in the
2274 following ways:
2275 1. Variable assignment lists preceding the command remain in effect
2276 when the command completes.
2277 2. I/O redirections are processed after variable assignments.
2278 3. Errors cause a script that contains them to abort.
2279 4. They are not valid function names.
2280 5. Words following a command preceded by †† that are in the format
2281 of a variable assignment are expanded with the same rules as a
2282 variable assignment. This means that tilde substitution is per‐
2283 formed after the = sign and field splitting and file name gener‐
2284 ation are not performed. These are called declaration built-
2285 ins.
2286 † : [ arg ... ]
2288 The command only expands parameters.
2289 † . name [ arg ... ]
2291 If name is a function defined with the function name reserved
2292 word syntax, the function is executed in the current environment
2293 (as if it had been defined with the name() syntax.) Otherwise
2294 if name refers to a file, the file is read in its entirety and
2295 the commands are executed in the current shell environment. The
2296 search path specified by PATH is used to find the directory con‐
2297 taining the file. If any arguments arg are given, they become
2298 the positional parameters while processing the . command and
2299 the original positional parameters are restored upon completion.
2300 Otherwise the positional parameters are unchanged. The exit
2301 status is the exit status of the last command executed.
2302 †† alias [ -ptx ] [ name[ =value ] ] ...
2304 alias with no arguments prints the list of aliases in the form
2305 name=value on standard output. The -p option causes the word
2306 alias to be inserted before each one. When one or more argu‐
2307 ments are given, an alias is defined for each name whose value
2308 is given. A trailing space in value causes the next word to be
2309 checked for alias substitution. The obsolete -t option is used
2310 to set and list tracked aliases. The value of a tracked alias
2311 is the full pathname corresponding to the given name. The value
2312 becomes undefined when the value of PATH is reset but the alias
2313 remains tracked. Without the -t option, for each name in the
2314 argument list for which no value is given, the name and value of
2315 the alias is printed. The obsolete -x option has no effect.
2316 The exit status is non-zero if a name is given, but no value,
2317 and no alias has been defined for the name.
2318 bg [ job... ]
2320 This command is only on systems that support job control. Puts
2321 each specified job into the background. The current job is put
2322 in the background if job is not specified. See Jobs for a
2323 description of the format of job.
2324 † break [ n ]
2326 Exit from the enclosing for, while, until, or select loop, if
2327 any. If n is specified, then break n levels.
2328 builtin [ -dsp ] [ -f file ] [ name ... ]
2330 If name is not specified, and no -f option is specified, the
2331 built-ins are printed on standard output. The -s option prints
2332 only the special built-ins. Otherwise, each name represents the
2333 pathname whose basename is the name of the built-in. The entry
2334 point function name is determined by prepending b_ to the built-
2335 in name. A built-in specified by a pathname will only be exe‐
2336 cuted when that pathname would be found during the path search.
2337 Built-ins found in libraries loaded via the .paths file will be
2338 associate with the pathname of the directory containing the
2339 .paths file.
2340 The ISO C/C++ prototype is b_mycommand(int argc, char *argv[],
2341 void *context) for the builtin command mycommand where argv is
2342 array an of argc elements and context is an optional pointer to
2343 a Shell_t structure as described in <ast/shell.h>.
2344 Special built-ins cannot be bound to a pathname or deleted. The
2345 -d option deletes each of the given built-ins. On systems that
2346 support dynamic loading, the -f option names a shared library
2347 containing the code for built-ins. The shared library prefix
2348 and/or suffix, which depend on the system, can be omitted. Once
2349 a library is loaded, its symbols become available for subsequent
2350 invocations of builtin. Multiple libraries can be specified
2351 with separate invocations of the builtin command. Libraries are
2352 searched in the reverse order in which they are specified. When
2353 a library is loaded, it looks for a function in the library
2354 whose name is lib_init() and invokes this function with an argu‐
2355 ment of 0.
2356 The -p causes the output to be in a form of builtin commands
2357 that can be used as input to the shell to recreate the current
2358 set of builtins.
2359 cd [ -LP ] [ arg ]
2361 cd [ -LP ] old new
2362 This command can be in either of two forms. In the first form
2363 it changes the current directory to arg. If arg is - the direc‐
2364 tory is changed to the previous directory. The shell variable
2365 HOME is the default arg. The variable PWD is set to the current
2366 directory. The shell variable CDPATH defines the search path
2367 for the directory containing arg. Alternative directory names
2368 are separated by a colon (:). The default path is <null> (spec‐
2369 ifying the current directory). Note that the current directory
2370 is specified by a null path name, which can appear immediately
2371 after the equal sign or between the colon delimiters anywhere
2372 else in the path list. If arg begins with a / then the search
2373 path is not used. Otherwise, each directory in the path is
2374 searched for arg.
2375 The second form of cd substitutes the string new for the string
2376 old in the current directory name, PWD, and tries to change to
2377 this new directory.
2378 By default, symbolic link names are treated literally when find‐
2379 ing the directory name. This is equivalent to the -L option.
2380 The -P option causes symbolic links to be resolved when deter‐
2381 mining the directory. The last instance of -L or -P on the com‐
2382 mand line determines which method is used.
2383 The cd command may not be executed by rksh.
2384 command [ -pvxV ] name [ arg ... ]
2386 Without the -v or -V options, command executes name with the
2387 arguments given by arg. The -p option causes a default path to
2388 be searched rather than the one defined by the value of PATH.
2389 Functions will not be searched for when finding name. In addi‐
2390 tion, if name refers to a special built-in, none of the special
2391 properties associated with the leading daggers will be honored.
2392 (For example, the predefined alias redirect=′command exec′ pre‐
2393 vents a script from terminating when an invalid redirection is
2394 given.) With the -x option, if command execution would result
2395 in a failure because there are too many arguments, errno E2BIG,
2396 the shell will invoke command name multiple times with a subset
2397 of the arguments on each invocation. Arguments that occur prior
2398 to the first word that expands to multiple arguments and after
2399 the last word that expands to multiple arguments will be passed
2400 on each invocation. The exit status will be the maximum invoca‐
2401 tion exit status. With the -v option, command is equivalent to
2402 the built-in whence command described below. The -V option
2403 causes command to act like whence -v.
2404 † continue [ n ]
2406 Resume the next iteration of the enclosing for, while, until, or
2407 select loop. If n is specified, then resume at the n-th enclos‐
2408 ing loop.
2409 disown [ job... ]
2411 Causes the shell not to send a HUP signal to each given job, or
2412 all active jobs if job is omitted, when a login shell termi‐
2413 nates.
2414 echo [ -n -e ] [ arg ... ]
2416 echo builtin prints all of its arguments separated by space and
2417 terminated by new-line. -n will skip putting a newline charac‐
2418 ter at the end of output. If -e is set, it will enable inter‐
2419 preting escape sequences.
2420 †† enum [ -i ] type[=(value ...) ]
2423 Creates a declaration command named type that is an integer type
2424 that allows one of the specified values as enumeration names.
2425 If =(value ...) is omitted, then type must be an indexed array
2426 variable with at least two elements and the values are taken
2427 from this array variable. If -i is specified the values are
2428 case insensitive.
2429 When an enumeration variable is used in arithmetic expression,
2430 its value is the index into the array that defined it starting
2431 from index 0. Enumeration strings can be used in an arithmetic
2432 expression when comparing against an enumeration variable.
2433 Also, each non-subscripted enumeration variable followed by
2434 .name where name is one of the enumeration names expands to the
2435 index corresponding to name.
2436 The enum _Bool is created with values true and false. The pre‐
2437 defined alias bool is defined as _Bool.
2438 † eval [ arg ... ]
2440 The arguments are read as input to the shell and the resulting
2441 command(s) executed.
2442 † exec [ -c ] [ -a name ] [ arg ... ]
2444 If arg is given, the command specified by the arguments is exe‐
2445 cuted in place of this shell without creating a new process.
2446 The -c option causes the environment to be cleared before apply‐
2447 ing variable assignments associated with the exec invocation.
2448 The -a option causes name rather than the first arg, to become
2449 argv[0] for the new process. Input/output arguments may appear
2450 and affect the current process. If arg is not given, the effect
2451 of this command is to modify file descriptors as prescribed by
2452 the input/output redirection list. In this case, any file
2453 descriptor numbers greater than 2 that are opened with this
2454 mechanism are closed when invoking another program.
2455 † exit [ n ]
2457 Causes the shell to exit with the exit status specified by n.
2458 The value will be the least significant 8 bits of the specified
2459 status. If n is omitted, then the exit status is that of the
2460 last command executed. An end-of-file will also cause the shell
2461 to exit except for a shell which has the ignoreeof option (see
2462 set below) turned on.
2463 †† export [ -p ] [ name[=value] ] ...
2465 If name is not given, the names and values of each variable with
2466 the export attribute are printed with the values quoted in a
2467 manner that allows them to be re-input. The export command is
2468 the same as typeset -x except that if you use export within a
2469 function, no local variable is created. The -p option causes
2470 the word export to be inserted before each one. Otherwise, the
2471 given names are marked for automatic export to the environment
2472 of subsequently-executed commands.
2473 false Does nothing, and exits 1. Used with until for infinite loops.
2475 fg [ job... ]
2477 This command is only on systems that support job control. Each
2478 job specified is brought to the foreground and waited for in the
2479 specified order. Otherwise, the current job is brought into the
2480 foreground. See Jobs for a description of the format of job.
2481 getopts [ -a name ] optstring vname [ arg ... ]
2483 Checks arg for legal options. If arg is omitted, the positional
2484 parameters are used. An option argument begins with a + or a -.
2485 An option not beginning with + or - or the argument -- ends the
2486 options. Options beginning with + are only recognized when opt‐
2487 string begins with a +. optstring contains the letters that
2488 getopts recognizes. If a letter is followed by a :, that option
2489 is expected to have an argument. The options can be separated
2490 from the argument by blanks. The option -? causes getopts to
2491 generate a usage message on standard error. The -a argument can
2492 be used to specify the name to use for the usage message, which
2493 defaults to $0.
2494 getopts places the next option letter it finds inside variable
2495 vname each time it is invoked. The option letter will be
2496 prepended with a + when arg begins with a +. The index of the
2497 next arg is stored in OPTIND. The option argument, if any, gets
2498 stored in OPTARG.
2499 A leading : in optstring causes getopts to store the letter of
2500 an invalid option in OPTARG, and to set vname to ? for an
2501 unknown option and to : when a required option argument is miss‐
2502 ing. Otherwise, getopts prints an error message. The exit sta‐
2503 tus is non-zero when there are no more options.
2504 There is no way to specify any of the options :, +, -, ?, [, and
2505 ]. The option # can only be specified as the first option.
2506 hist [ -e ename ] [ -nlr ] [ first [ last ] ]
2508 hist -s [ old=new ] [ command ]
2509 In the first form, a range of commands from first to last is
2510 selected from the last HISTSIZE commands that were typed at the
2511 terminal. The arguments first and last may be specified as a
2512 number or as a string. A string is used to locate the most
2513 recent command starting with the given string. A negative num‐
2514 ber is used as an offset to the current command number. If the
2515 -l option is selected, the commands are listed on standard out‐
2516 put. Otherwise, the editor program ename is invoked on a file
2517 containing these keyboard commands. If ename is not supplied,
2518 then the value of the variable HISTEDIT is used. If HISTEDIT is
2519 not set, then FCEDIT (default /bin/ed) is used as the editor.
2520 When editing is complete, the edited command(s) is executed if
2521 the changes have been saved. If last is not specified, then it
2522 will be set to first. If first is not specified, the default is
2523 the previous command for editing and -16 for listing. The
2524 option -r reverses the order of the commands and the option -n
2525 suppresses command numbers when listing. In the second form,
2526 command is interpreted as first described above and defaults to
2527 the last command executed. The resulting command is executed
2528 after the optional substitution old=new is performed.
2529 jobs [ -lnp ] [ job ... ]
2531 Lists information about each given job; or all active jobs if
2532 job is omitted. The -l option lists process ids in addition to
2533 the normal information. The -n option only displays jobs that
2534 have stopped or exited since last notified. The -p option
2535 causes only the process group to be listed. See Jobs for a
2536 description of the format of job.
2537 kill [ -s signame ] [ -q n ] job ...
2539 kill [ -n signum ] [ -q n ] job ...
2540 kill -Ll [ sig ... ]
2541 Sends either the TERM (terminate) signal or the specified signal
2542 to the specified jobs or processes. Signals are either given by
2543 number with the -n option or by name with the -s option (as
2544 given in <signal.h>, stripped of the prefix ``SIG'' with the
2545 exception that SIGCLD is named CHLD). For backward compatibil‐
2546 ity, the n and s can be omitted and the number or name placed
2547 immediately after the -. If the signal being sent is TERM (ter‐
2548 minate) or HUP (hangup), then the job or process will be sent a
2549 CONT (continue) signal if it is stopped. The argument job can
2550 be the process id of a process that is not a member of one of
2551 the active jobs. See Jobs for a description of the format of
2552 job. In the third form, kill -l, or kill -L, if sig is not
2553 specified, the signal names are listed. The -l option list only
2554 the signal names. -L options lists each signal name and corre‐
2555 sponding number. Otherwise, for each sig that is a name, the
2556 corresponding signal number is listed. For each sig that is a
2557 number, the signal name corresponding to the least significant 8
2558 bits of sig is listed.
2559 On systems that support sigqueue(2) the -q option can be used to
2560 send a queued signal with message number n. Each specified job
2561 must be a positive number. On systems that do not support
2562 sigqueue(2), a signal is sent without the message number n and
2563 the signal will not be queued. If the signal cannot be queued
2564 because of a return of EAGAIN, the exit status will be 2.
2565 let arg ...
2567 Each arg is a separate arithmetic expression to be evaluated.
2568 let only recognizes octal constants starting with 0 when the set
2569 option letoctal is on. See Arithmetic Evaluation above, for a
2570 description of arithmetic expression evaluation.
2571 The exit status is 0 if the value of the last expression is non-
2572 zero, and 1 otherwise.
2573 † newgrp [ arg ... ]
2575 Equivalent to exec /bin/newgrp arg ....
2576 print [ -CRenprsv ] [ -u unit] [ -f format ] [ arg ... ]
2578 With no options or with option - or --, each arg is printed on
2579 standard output. The -f option causes the arguments to be
2580 printed as described by printf. In this case, any e, n, r, R
2581 options are ignored. Otherwise, unless the -C, -R, -r, or -v
2582 are specified, the following escape conventions will be applied:
2583 \a The alert character (ascii 07).
2584 \b The backspace character (ascii 010).
2585 \c Causes print to end without processing more arguments and
2586 not adding a new-line.
2587 \f The formfeed character (ascii 014).
2588 \n The new-line character (ascii 012).
2589 \r The carriage return character (ascii 015).
2590 \t The tab character (ascii 011).
2591 \v The vertical tab character (ascii 013).
2592 \E The escape character (ascii 033).
2593 \\ The backslash character \.
2594 \0x The character defined by the 1, 2, or 3-digit octal
2595 string given by x.
2596 The -R option will print all subsequent arguments and options
2598 other than -n. The -e causes the above escape conventions to be
2599 applied. This is the default behavior. It reverses the effect
2600 of an earlier -r. The -p option causes the arguments to be
2601 written onto the pipe of the process spawned with ⎪& instead of
2602 standard output. The -v option treats each arg as a variable
2603 name and writes the value in the printf %B format. The -C
2604 option treats each arg as a variable name and writes the value
2605 in the printf %#B format. The -s option causes the arguments to
2606 be written onto the history file instead of standard output.
2607 The -u option can be used to specify a one digit file descriptor
2608 unit number unit on which the output will be placed. The
2609 default is 1. If the option -n is used, no new-line is added to
2610 the output.
2611 printf [ -v varname ] format [ arg ... ]
2613 The arguments arg are printed on standard output in accordance
2614 with the ANSI-C formatting rules associated with the format
2615 string format. If the number of arguments exceeds the number of
2616 format specifications, the format string is reused to format
2617 remaining arguments. If the -v option is specified the output
2618 is assigned to the variable varname. The following extensions
2619 can also be used:
2620 %b A %b format can be used instead of %s to cause escape
2621 sequences in the corresponding arg to be expanded as
2622 described in print.
2623 %B A %B option causes each of the arguments to be treated as
2624 variable names and the binary value of variable will be
2625 printed. The alternate flag # causes a compound variable
2626 to be output on a single line. This is most useful for
2627 compound variables and variables whose attribute is -b.
2628 %H A %H format can be used instead of %s to cause characters
2629 in arg that are special in HTML and XML to be output as
2630 their entity name. The alternate flag # formats the out‐
2631 put for use as a URI.
2632 %P A %P format can be used instead of %s to cause arg to be
2633 interpreted as an extended regular expression and be
2634 printed as a shell pattern.
2635 %R A %R format can be used instead of %s to cause arg to be
2636 interpreted as a shell pattern and to be printed as an
2637 extended regular expression.
2638 %q A %q format can be used instead of %s to cause the
2639 resulting string to be quoted in a manner than can be
2640 reinput to the shell. When q is preceded by the alterna‐
2641 tive format specifier, #, the string is quoted in manner
2642 suitable as a field in a .csv format file.
2643 %(date-format)T
2644 A %(date-format)T format can be use to treat an argument
2645 as a date/time string and to format the date/time accord‐
2646 ing to the date-format as defined for the date(1) com‐
2647 mand. Values specified as digits are interpreted as
2648 described in the touch(1) command.
2649 %Z A %Z format will output a byte whose value is 0.
2650 %d The precision field of the %d format can be followed by a
2651 . and the output base. In this case, the # flag charac‐
2652 ter causes base# to be prepended.
2653 # The # flag, when used with the %d format without an out‐
2654 put base, displays the output in powers of 1000 indicated
2655 by one of the following suffixes: k M G T P E, and when
2656 used with the %i format displays the output in powers of
2657 1024 indicated by one of the following suffixes: Ki Mi Gi
2658 Ti Pi Ei.
2659 = The = flag centers the output within the specified field
2660 width.
2661 L The L flag, when used with the %c or %s formats, treats
2662 precision as character width instead of byte count.
2663 , The , flag, when used with the %d or %f formats, sepa‐
2664 rates groups of digits with the grouping delimiter (, on
2665 groups of 3 in the C locale.)
2666 pwd [ -LP ] [ -f fd ]
2668 Outputs the value of the current working directory. The -L
2669 option is the default; it prints the logical name of the current
2670 directory. If the -P option is given, all symbolic links are
2671 resolved from the name. The last instance of -L or -P on the
2672 command line determines which method is used. If the -f option
2673 is specified, the directory name corresponding to file descrip‐
2674 tor fd is outputted.
2675 read [ -AaCSprsv ] [ -d delim] [ -n n] [ -N n] [ -m method] [ -t time‐
2677 out] [ -u unit] [ vname?prompt ] [ vname ... ]
2678 The shell input mechanism. One line is read and is broken up
2679 into fields using the characters in IFS as separators. The
2680 escape character, \, is used to remove any special meaning for
2681 the next character and for line continuation. The -d option
2682 causes the read to continue to the first character of delim
2683 rather than new-line. The -n option causes at most n bytes to
2684 read rather a full line but will return when reading from a slow
2685 device as soon as any characters have been read. The -N option
2686 causes exactly n to be read unless an end-of-file has been
2687 encountered or the read times out because of the -t option. In
2688 raw mode, -r, the \ character is not treated specially. The
2689 first field is assigned to the first vname, the second field to
2690 the second vname, etc., with leftover fields assigned to the
2691 last vname. When vname has the binary attribute and -n or -N is
2692 specified, the bytes that are read are stored directly into the
2693 variable. If the -v is specified, then the value of the first
2694 vname will be used as a default value when reading from a termi‐
2695 nal device. The -A option causes the variable vname to be unset
2696 and each field that is read to be stored in successive elements
2697 of the indexed array vname. -a is an alias for -A. The -m
2698 option reads a compound variable with the read method defined by
2699 method. Currently, only the json and ksh methods exist. The -C
2700 option causes the variable vname to be read as a compound vari‐
2701 able. Blanks will be ignored when finding the beginning open
2702 parenthesis. This is equivalent to -m ksh. The -S option
2703 causes the line to be treated like a record in a .csv format
2704 file so that double quotes can be used to allow the delimiter
2705 character and the new-line character to appear within a field.
2706 The -p option causes the input line to be taken from the input
2707 pipe of a process spawned by the shell using ⎪&. If the -s
2708 option is present, the input will be saved as a command in the
2709 history file. The option -u can be used to specify a one digit
2710 file descriptor unit unit to read from. The file descriptor can
2711 be opened with the exec special built-in command. The default
2712 value of unit n is 0. The option -t is used to specify a time‐
2713 out in seconds when reading from a terminal or pipe. If vname
2714 is omitted, then REPLY is used as the default vname. An end-of-
2715 file with the -p option causes cleanup for this process so that
2716 another can be spawned. If the first argument contains a ?, the
2717 remainder of this word is used as a prompt on standard error
2718 when the shell is interactive. The exit status is 0 unless an
2719 end-of-file is encountered or read has timed out.
2720 †† readonly [ -p ] [ vname[=value] ] ...
2722 If vname is not given, the names and values of each variable
2723 with the readonly attribute is printed with the values quoted in
2724 a manner that allows them to be re-inputted. The -p option
2725 causes the word readonly to be inserted before each one. Other‐
2726 wise, the given vnames are marked readonly and these names can‐
2727 not be changed by subsequent assignment. When defining a type,
2728 if the value of a readonly sub-variable is not defined the value
2729 is required when creating each instance.
2730 † return [ n ]
2732 Causes a shell function or . script to return to the invoking
2733 script with the exit status specified by n. The value will be
2734 the least significant 8 bits of the specified status. If n is
2735 omitted, then the return status is that of the last command exe‐
2736 cuted. If return is invoked while not in a function or a .
2737 script, then it behaves the same as exit.
2738 † set [ ±BCGabefhkmnoprstuvx ] [ ±o [ option ] ] ... [ ±A vname ] [ -K
2740 keylist ] [ arg ... ]
2741 The options for this command have meaning as follows:
2742 -A Array assignment. If arg is specified, unset the vari‐
2743 able vname and assign values sequentially from the arg
2744 list. If +A is used, the variable vname is not unset
2745 first.
2746 -B Enable brace group expansion. On by default.
2747 -C Prevents redirection > from truncating existing files.
2748 Files that are created are opened with the O_EXCL mode.
2749 Requires >⎪ to truncate a file when turned on.
2750 -G Causes the pattern ** by itself to match files and zero
2751 or more directories and sub-directories when used for
2752 file name generation. If followed by a / only directo‐
2753 ries and sub-directories are matched.
2754 -H Enable !-style history expansion similar to csh(1).
2755 -K When no arguments are specified, it is used along with
2756 -s to specify the sort fields and sort options for sort‐
2757 ing an array. (See "Array Sorting" above for the
2758 description of the keylist option.)
2759 -a All subsequent variables that are defined are automati‐
2760 cally exported.
2761 -b Prints job completion messages as soon as a background
2762 job changes state rather than waiting for the next
2763 prompt.
2764 -e Unless contained in a ⎪⎪ or && command, or the command
2765 following an if while or until command or in the pipe‐
2766 line following !, if a command has a non-zero exit sta‐
2767 tus, execute the ERR trap, if set, and exit. This mode
2768 is disabled while reading profiles.
2769 -f Disables file name generation.
2770 -h Each command becomes a tracked alias when first encoun‐
2771 tered.
2772 -k (Obsolete). All variable assignment arguments are placed
2773 in the environment for a command, not just those that
2774 precede the command name.
2775 -m Background jobs will run in a separate process group and
2776 a line will print upon completion. The exit status of
2777 background jobs is reported in a completion message. On
2778 systems with job control, this option is turned on auto‐
2779 matically for interactive shells.
2780 -n Read commands and check them for syntax errors, but do
2781 not execute them. Ignored for interactive shells.
2782 -o The following argument can be one of the following
2783 option names:
2784 allexport
2785 Same as -a.
2786 bgnice All background jobs are run at a lower priority.
2787 This is the default mode.
2788 braceexpand
2789 Same as -B.
2790 emacs Puts you in an emacs style in-line editor for
2791 command entry.
2792 errexit Same as -e.
2793 globstar
2794 Same as -G.
2795 gmacs Puts you in a gmacs style in-line editor for
2796 command entry.
2797 histexpand
2798 Same as -H.
2799 ignoreeof
2800 The shell will not exit on end-of-file. The
2801 command exit must be used.
2802 keyword Same as -k.
2803 letoctal
2804 The let command allows octal constants starting
2805 with 0.
2806 markdirs
2807 All directory names resulting from file name
2808 generation have a trailing / appended.
2809 monitor Same as -m.
2810 multiline
2811 The built-in editors will use multiple lines on
2812 the screen for lines that are longer than the
2813 width of the screen. This may not work for all
2814 terminals.
2815 noclobber
2816 Same as -C.
2817 noexec Same as -n.
2818 noglob Same as -f.
2819 nolog Do not save function definitions in the history
2820 file.
2821 notify Same as -b.
2822 nounset Same as -u.
2823 pipefail
2824 A pipeline will not complete until all compo‐
2825 nents of the pipeline have completed, and the
2826 return value will be the value of the last non-
2827 zero command to fail or zero if no command has
2828 failed.
2829 privileged
2830 Same as -p.
2831 showme When enabled, simple commands or pipelines pre‐
2832 ceded by a semicolon (;) will be displayed as if
2833 the xtrace option were enabled but will not be
2834 executed. Otherwise, the leading ; will be
2835 ignored.
2836 trackall
2837 Same as -h.
2838 verbose Same as -v.
2839 vi Puts you in insert mode of a vi style in-line
2840 editor until you hit the escape character 033.
2841 This puts you in control mode. A return sends
2842 the line.
2843 viraw Each character is processed as it is typed in vi
2844 mode. This is now always enabled. Disabling the
2845 option at run time has no effect.
2846 xtrace Same as -x.
2847 If no option name is supplied, then the current option
2848 settings are printed.
2849 -p Disables processing of the $HOME/.profile file and uses
2850 the file /etc/suid_profile instead of the ENV file.
2851 This mode is on whenever the effective uid (gid) is not
2852 equal to the real uid (gid). Turning this off causes
2853 the effective uid and gid to be set to the real uid and
2854 gid.
2855 -r Enables the restricted shell. This option cannot be
2856 unset once set.
2857 -s Sort the positional parameters lexicographically. When
2858 used with -A
2859 sorts the elements of the array.
2860 -t (Obsolete). Exit after reading and executing one
2861 command.
2862 -u Treat unset parameters as an error when substituting.
2863 -v Print shell input lines as they are read.
2864 -x Print commands and their arguments as they are executed.
2865 -- Do not change any of the options; useful in setting $1
2866 to a value beginning with -. If no arguments follow
2867 this option then the positional parameters are unset.
2868 As an obsolete feature, if the first arg is - then the -x and -v
2870 options are turned off and the next arg is treated as the first
2871 argument. Using + rather than - causes these options to be
2872 turned off. These options can also be used upon invocation of
2873 the shell. The current set of options may be found in $-.
2874 Unless -A is specified, the remaining arguments are positional
2875 parameters and are assigned, in order, to $1 $2 .... If no
2876 arguments are given, then the names and values of all variables
2877 are printed on the standard output.
2878 † shift [ n ]
2880 The positional parameters from $n+1 ... are renamed $1 ... ,
2881 default n is 1. The parameter n can be any arithmetic expres‐
2882 sion that evaluates to a non-negative number less than or equal
2883 to $#.
2884 sleep seconds
2886 Suspends execution for the number of decimal seconds or frac‐
2887 tions of a second given by seconds. seconds A suffix of one of
2888 smhd can be used to indicate seconds, minutes, hours, and days
2889 respectively. Seconds can also be specified using a date/time
2890 format.
2891 times Display CPU time used by the shell and all of its child pro‐
2893 cesses.
2894 † trap [ -alp ] [ action ] [ sig ] ...
2896 The -p option causes the trap action associated with each trap
2897 as specified by the arguments to be printed with appropriate
2898 quoting. Otherwise, action will be processed as if it were an
2899 argument to eval when the shell receives signal(s) sig.
2900 The -a option causes the current trap setting to be appended to
2901 action. Each sig can be given as a number or as the name of the
2902 signal. Trap commands are executed in order of signal number.
2903 Any attempt to set a trap on a signal that was ignored on entry
2904 to the current shell is ineffective. If action is omitted and
2905 the first sig is a number, or if action is -, then the trap(s)
2906 for each sig are reset to their original values. If action is
2907 the null string then this signal is ignored by the shell and by
2908 the commands it invokes.
2909 If sig is ERR then action will be executed whenever a command
2910 has a non-zero exit status.
2911 If sig is DEBUG then action will be executed before each com‐
2912 mand. The variable .sh.command will contain the contents of the
2913 current command line when action is running. If the exit status
2914 of the trap is 2 the command will not be executed. If the exit
2915 status of the trap is 255 and inside a function or a dot script,
2916 the function or dot script will return.
2917 If sig is 0 or EXIT and the trap statement is executed inside
2918 the body of a function defined with the function name syntax,
2919 then the command action is executed after the function com‐
2920 pletes. For a trap set outside any function then the command
2921 action is executed on exit from the shell.
2922 If sig is KEYBD, then action will be executed whenever a key is
2923 read while in emacs, gmacs, or vi mode. The trap command with
2924 no arguments prints a list of commands associated with each sig‐
2925 nal number.
2926 An exit or return without an argument in a trap action will pre‐
2927 serve the exit status of the command that invoked the trap.
2928 action. Each sig can be given as a number or as the name of the
2929 signal. Trap commands are executed in order of signal number.
2930 Any attempt to set a trap on a signal that was ignored on entry
2931 to the current shell is ineffective. If action is omitted and
2932 the first sig is a number, or if action is -, then the trap(s)
2933 for each sig are reset to their original values. The -l option
2934 lists the signals and their numbers to standard output.
2935 true Does nothing, and exits 0. Used with while for infinite loops.
2937 †† typeset [ ±ACHSfblmnprstux ] [ ±EFLRXZi[n] ] [ +-M [ mapname ] ]
2939 [ -T [ tname=(assign_list) ] ] [ -h str ] [ -a [type] ] [ vname[=value
2940 ] ] ...
2941 Sets attributes and values for shell variables and functions.
2942 When invoked inside a function defined with the function name
2943 syntax, a new instance of the variable vname is created, and the
2944 variable's value and type are restored when the function com‐
2945 pletes. The following list of attributes may be specified:
2946 -A Declares vname to be an associative array. Subscripts
2947 are strings rather than arithmetic expressions.
2948 -C causes each vname to be a compound variable. value names
2949 a compound variable it is copied into vname. Otherwise,
2950 it unsets each vname.
2951 -a Declares vname to be an indexed array. If type is speci‐
2952 fied, it must be the name of an enumeration type created
2953 with the enum command and it allows enumeration constants
2954 to be used as subscripts.
2955 -E Declares vname to be a double precision floating point
2956 number. If n is non-zero, it defines the number of sig‐
2957 nificant figures that are used when expanding vname.
2958 Otherwise, ten significant figures will be used.
2959 -F Declares vname to be a double precision floating point
2960 number. If n is non-zero, it defines the number of
2961 places after the decimal point that are used when expand‐
2962 ing vname. Otherwise ten places after the decimal point
2963 will be used.
2964 -H This option provides UNIX to host-name file mapping on
2965 non-UNIX machines.
2966 -L Left justify and remove leading blanks from value. If n
2967 is non-zero, it defines the width of the field, otherwise
2968 it is determined by the width of the value of first
2969 assignment. When the variable is assigned to, it is
2970 filled on the right with blanks or truncated, if neces‐
2971 sary, to fit into the field. The -R option is turned
2972 off.
2973 -M Use the character mapping mapping defined by wctrans(3).
2974 such as tolower and toupper when assigning a value to
2975 each of the specified operands. When mapping is speci‐
2976 fied and there are not operands, all variables that use
2977 this mapping are written to standard output. When map‐
2978 ping is omitted and there are no operands, all mapped
2979 variables are written to standard output.
2980 -R Right justify and fill with leading blanks. If n is non-
2981 zero, it defines the width of the field, otherwise it is
2982 determined by the width of the value of first assignment.
2983 The field is left filled with blanks or truncated from
2984 the end if the variable is reassigned. The -L option is
2985 turned off.
2986 -S When used within the assign_list of a type definition, it
2987 causes the specified sub-variable to be shared by all
2988 instances of the type. When used inside a function
2989 defined with the function reserved word, the specified
2990 variables will have function static scope. Otherwise,
2991 the variable is unset prior to processing the assignment
2992 list.
2993 -T If followed by tname, it creates a type named by tname
2994 using the compound assignment assign_list to tname. Oth‐
2995 erwise, it writes all the type definitions to standard
2996 output.
2997 -X Declares vname to be a double precision floating point
2998 number and expands using the %a format of ISO-C99. If n
2999 is non-zero, it defines the number of hex digits after
3000 the radix point that is used when expanding vname. The
3001 default is 10.
3002 -Z Right justify and fill with leading zeros if the first
3003 non-blank character is a digit and the -L option has not
3004 been set. Remove leading zeros if the -L option is also
3005 set. If n is non-zero, it defines the width of the
3006 field, otherwise it is determined by the width of the
3007 value of first assignment.
3008 -f The names refer to function names rather than variable
3009 names. No assignments can be made and the only other
3010 valid options are -S, -t, -u and -x. The -S can be used
3011 with discipline functions defined in a type to indicate
3012 that the function is static. For a static function, the
3013 same method will be used by all instances of that type no
3014 matter which instance references it. In addition, it can
3015 only use value of variables from the original type defi‐
3016 nition. These discipline functions cannot be redefined
3017 in any type instance. The -t option turns on execution
3018 tracing for this function. The -u option causes this
3019 function to be marked undefined. The FPATH variable will
3020 be searched to find the function definition when the
3021 function is referenced. If no options other than -f is
3022 specified, then the function definition will be displayed
3023 on standard output. If +f is specified, then a line con‐
3024 taining the function name followed by a shell comment
3025 containing the line number and path name of the file
3026 where this function was defined, if any, is displayed.
3027 The exit status can be used to determine whether the
3028 function is defined so that typeset -f .sh.math.name will
3029 return 0 when math function name is defined and non-zero
3030 otherwise.
3031 -b The variable can hold any number of bytes of data. The
3032 data can be text or binary. The value is represented by
3033 the base64 encoding of the data. If -Z is also speci‐
3034 fied, the size in bytes of the data in the buffer will be
3035 determined by the size associated with the -Z. If the
3036 base64 string assigned results in more data, it will be
3037 truncated. Otherwise, it will be filled with bytes whose
3038 value is zero. The printf format %B can be used to out‐
3039 put the actual data in this buffer instead of the base64
3040 encoding of the data.
3041 -h Used within type definitions to add information when gen‐
3042 erating information about the sub-variable on the man
3043 page. It is ignored when used outside of a type defini‐
3044 tion. When used with -f the information is associated
3045 with the corresponding discipline function.
3046 -i Declares vname to be represented internally as integer.
3047 The right hand side of an assignment is evaluated as an
3048 arithmetic expression when assigning to an integer. If n
3049 is non-zero, it defines the output arithmetic base, oth‐
3050 erwise the output base will be ten.
3051 -l Used with -i, -E or -F, to indicate long integer, or long
3052 double. Otherwise, all upper-case characters are con‐
3053 verted to lower-case. The upper-case option, -u, is
3054 turned off. Equivalent to -M tolower .
3055 -m moves or renames the variable. The value is the name of
3056 a variable whose value will be moved to vname. The orig‐
3057 inal variable will be unset. Cannot be used with any
3058 other options.
3059 -n Declares vname to be a reference to the variable whose
3060 name is defined by the value of variable vname. This is
3061 usually used to reference a variable inside a function
3062 whose name has been passed as an argument. Cannot be
3063 used with any other options.
3064 -p The name, attributes and values for the given vnames are
3065 written on standard output in a form that can be used as
3066 shell input. If +p is specified, then the values are not
3067 displayed.
3068 -r The given vnames are marked readonly and these names can‐
3069 not be changed by subsequent assignment.
3070 -s Used with -i, -E or -F, to indicate short integer, or
3071 float.
3072 -t Tags the variables. Tags are user definable and have no
3073 special meaning to the shell.
3074 -u When given along with -i, specifies unsigned integer.
3075 Otherwise, all lower-case characters are converted to
3076 upper-case. The lower-case option, -l, is turned off.
3077 Equivalent to -M toupper .
3078 -x The given vnames are marked for automatic export to the
3079 environment of subsequently-executed commands. Variables
3080 whose names contain a . cannot be exported.
3081 The -i attribute cannot be specified along with -R, -L, -Z, or
3083 -f.
3084 Using + rather than - causes these options to be turned off. If
3086 no vname arguments are given, a list of vnames (and optionally
3087 the values) of the variables is printed. (Using + rather than -
3088 keeps the values from being printed.) The -p option causes
3089 typeset followed by the option letters to be printed before each
3090 name rather than the names of the options. If any option other
3091 than -p is given, only those variables which have all of the
3092 given options are printed. Otherwise, the vnames and attributes
3093 of all variables that have attributes are printed.
3094 ulimit [ -HSacdfmnpstv ] [ limit ]
3096 Set or display a resource limit. The available resource limits
3097 are listed below. Many systems do not support one or more of
3098 these limits. The limit for a specified resource is set when
3099 limit is specified. The value of limit can be a number in the
3100 unit specified below with each resource, or the value unlimited.
3101 The -H and -S options specify whether the hard limit or the soft
3102 limit for the given resource is set. A hard limit cannot be
3103 increased once it is set. A soft limit can be increased up to
3104 the value of the hard limit. If neither the H nor S option is
3105 specified, the limit applies to both. The current resource
3106 limit is printed when limit is omitted. In this case, the soft
3107 limit is printed unless H is specified. When more than one
3108 resource is specified, then the limit name and unit is printed
3109 before the value.
3110 -a Lists all of the current resource limits.
3111 -c The number of 512-byte blocks on the size of core dumps.
3112 -d The number of K-bytes on the size of the data area.
3113 -f The number of 512-byte blocks on files that can be writ‐
3114 ten by the current process or by child processes (files
3115 of any size may be read).
3116 -m The number of K-bytes on the size of physical memory.
3117 -n The number of file descriptors plus 1.
3118 -p The number of 512-byte blocks for pipe buffering.
3119 -s The number of K-bytes on the size of the stack area.
3120 -t The number of CPU seconds to be used by each process.
3121 -v The number of K-bytes for virtual memory.
3122 If no option is given, -f is assumed.
3124 umask [ -pS ] [ mask ]
3126 The user file-creation mask is set to mask (see umask(2)). mask
3127 can either be an octal number or a symbolic value as described
3128 in chmod(1). If a symbolic value is given, the new umask value
3129 is the complement of the result of applying mask to the comple‐
3130 ment of the previous umask value. If mask is omitted, the cur‐
3131 rent value of the mask is printed. The -S option causes the
3132 mode to be printed as a symbolic value. Otherwise, the mask is
3133 printed in octal. The -p option cause the output to be in a
3134 form that can be use for reinput.
3135 † unalias [ -a ] name ...
3137 The aliases given by the list of names are removed from the
3138 alias list. The -a option causes all the aliases to be unset.
3139 †unset [ -fnv ] vname ...
3141 The variables given by the list of vnames are unassigned, i.e.,
3142 except for sub-variables within a type, their values and
3143 attributes are erased. For sub-variables of a type, the values
3144 are reset to the default value from the type definition. Read‐
3145 only variables cannot be unset. If the -f option is set, then
3146 the names refer to function names. If the -v option is set,
3147 then the names refer to variable names. The -f option overrides
3148 -v. If -n is set and name is a name reference, then name will
3149 be unset rather than the variable that it references. The
3150 default is equivalent to -v. Unsetting LINENO, MAILCHECK,
3151 OPTARG, OPTIND, RANDOM, SECONDS, TMOUT, and _ removes their spe‐
3152 cial meaning even if they are subsequently assigned to.
3153 wait [ job ... ]
3155 Wait for the specified job and report its termination status.
3156 If job is not given, then all currently active child processes
3157 are waited for. The exit status from this command is that of
3158 the last process waited for if job is specified; otherwise it is
3159 zero. See Jobs for a description of the format of job.
3160 whence [ -afpv ] name ...
3162 For each name, indicate how it would be interpreted if used as a
3163 command name.
3164 The -v option produces a more verbose report. The -f option
3165 skips the search for functions. The -p option does a path
3166 search for name even if name is an alias, a function, or a
3167 reserved word. The -p option turns off the -v option. The -a
3168 option is similar to the -v option but causes all interpreta‐
3169 tions of the given name to be reported.
3170 Invocation.
3172 If the shell is invoked by exec(2), and the first character of argument
3173 zero ($0) is -, then the shell is assumed to be a login shell and com‐
3174 mands are read from /etc/profile and then from $HOME/.profile, if it
3175 exists. Alternatively, the option -l causes the shell to a treated as
3176 a login shell. Next, for interactive shells, commands are read from
3177 the file named by performing parameter expansion, command substitution,
3178 and arithmetic substitution on the value of the environment variable
3179 ENV if the file exists. If the -s option is not present and arg and a
3180 file by the name of arg exists, then it reads and executes this script.
3181 Otherwise, if the first arg does not contain a /, a path search is per‐
3182 formed on the first arg to determine the name of the script to execute.
3183 The script arg must have execute permission and any setuid and setgid
3184 settings will be ignored. If the script is not found on the path, arg
3185 is processed as if it named a built-in command or function. Commands
3186 are then read as described below; the following options are interpreted
3187 by the shell when it is invoked:
3188 -D A list of all double quoted strings that are preceded by a $
3190 will be printed on standard output and the shell will exit.
3191 This set of strings will be subject to language translation
3192 when the locale is not C or POSIX. No commands will be exe‐
3193 cuted.
3194 -E Reads the file named by the ENV variable or by $HOME/.kshrc if
3196 not defined after the profiles.
3197 -c If the -c option is present, then commands are read from the
3199 first arg. Any remaining arguments become positional parame‐
3200 ters starting at 0.
3201 -s If the -s option is present or if no arguments remain, then
3203 commands are read from the standard input. Shell output,
3204 except for the output of the Special Commands listed above, is
3205 written to file descriptor 2.
3206 -i If the -i option is present or if the shell input and error
3208 output are attached to a terminal (as told by tcgetattr(2)),
3209 then this shell is interactive. In this case TERM is ignored
3210 (so that kill 0 does not kill an interactive shell) and INTR is
3211 caught and ignored (so that wait is interruptible). In all
3212 cases, QUIT is ignored by the shell.
3213 -r If the -r option is present, the shell is a restricted shell.
3215 -P If -P or -o profile is present, the shell is a profile shell
3217 (see pfexec(1)).
3218 -R filename
3220 The -R filename option is used to generate a cross reference
3221 database that can be used by a separate utility to find defini‐
3222 tions and references for variables and commands. The filename
3223 argument specifies the generated database. A script file must
3224 be provided on the command line as well.
3225 The remaining options and arguments are described under the set command
3227 above. An optional - as the first argument is ignored.
3228 Rksh Only.
3230 Rksh is used to set up login names and execution environments whose
3231 capabilities are more controlled than those of the standard shell. The
3232 actions of rksh are identical to those of ksh, except that the follow‐
3233 ing are disallowed:
3234 Unsetting the restricted option.
3235 changing directory (see cd(1)),
3236 setting or unsetting the value or attributes of SHELL, ENV,
3237 FPATH, or PATH,
3238 specifying path or command names containing /,
3239 redirecting output (>, >|, <>, and >>).
3240 adding or deleting built-in commands.
3241 using command -p to invoke a command.
3242 The restrictions above are enforced after .profile and the ENV files
3244 are interpreted.
3245 When a command to be executed is found to be a shell procedure, rksh
3247 invokes ksh to execute it. Thus, it is possible to provide to the end-
3248 user shell procedures that have access to the full power of the stan‐
3249 dard shell, while imposing a limited menu of commands; this scheme
3250 assumes that the end-user does not have write and execute permissions
3251 in the same directory.
3252 The net effect of these rules is that the writer of the .profile has
3254 complete control over user actions, by performing guaranteed setup
3255 actions and leaving the user in an appropriate directory (probably not
3256 the login directory).
3257 The system administrator often sets up a directory of commands (e.g.,
3259 /usr/rbin) that can be safely invoked by rksh.
3260
3262 Errors detected by the shell, such as syntax errors, cause the shell to
3263 return a non-zero exit status. If the shell is being used non-interac‐
3264 tively, then execution of the shell file is abandoned unless the error
3265 occurs inside a subshell in which case the subshell is abandoned. Oth‐
3266 erwise, the shell returns the exit status of the last command executed
3267 (see also the exit command above). Run time errors detected by the
3268 shell are reported by printing the command or function name and the
3269 error condition. If the line number that the error occurred on is
3270 greater than one, then the line number is also printed in square brack‐
3271 ets ([]) after the command or function name.
3272
3274 /etc/profile
3275 The system wide initialization file, executed for login shells.
3276 $HOME/.profile
3278 The personal initialization file, executed for login shells
3279 after /etc/profile.
3280 $HOME/.kshrc
3282 Default personal initialization file, executed for interactive
3283 shells when ENV is not set.
3284 /etc/suid_profile
3286 Alternative initialization file, executed instead of the per‐
3287 sonal initialization file when the real and effective user or
3288 group id do not match.
3289 /dev/null
3291 NULL device
3292
3294 cat(1), cd(1), chmod(1), cut(1), date(1), egrep(1), echo(1), emacs(1),
3295 env(1), fgrep(1), gmacs(1), grep(1), newgrp(1), pfexec(1), stty(1),
3296 test(1), touch(1), umask(1), vi(1), dup(2), exec(2), fork(2), getpw‐
3297 nam(3), ioctl(2), lseek(2), paste(1), pathconf(2), pipe(2), sigset‐
3298 info(2), sysconf(2), umask(2), ulimit(2), wait(2), wctrans(3), rand(3),
3299 a.out(5), profile(5), environ(7).
3300 Morris I. Bolsky and David G. Korn, The New KornShell Command and Pro‐
3302 gramming Language, Prentice Hall, 1995.
3303 POSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC
3305 9945-2, IEEE, 1993.
3306
3308 If a command is executed, and then a command with the same name is
3309 installed in a directory in the search path before the directory where
3310 the original command was found, the shell will continue to exec the
3311 original command. Use the -t option of the alias command to correct
3312 this situation.
3313 Some very old shell scripts contain a ^ as a synonym for the pipe char‐
3315 acter ⎪.
3316 Using the hist built-in command within a compound command will cause
3318 the whole command to disappear from the history file.
3319 The built-in command . file reads the whole file before any commands
3321 are executed. Therefore, alias and unalias commands in the file will
3322 not apply to any commands defined in the file.
3323 Traps are not processed while a job is waiting for a foreground
3325 process. Thus, a trap on CHLD won't be executed until the foreground
3326 job terminates.
3327 It is a good idea to leave a space after the comma operator in arith‐
3329 metic expressions to prevent the comma from being interpreted as the
3330 decimal point character in certain locales.
3331 KSH(1)