1KSH(1) General Commands Manual KSH(1)
2
6 ksh, rksh, pfksh - KornShell, a standard/restricted command and pro‐
7 gramming language
8
10 ksh [ ±abcefhikmnoprstuvxBCDP ] [ -R file ] [ ±o option ] ... [ - ] [
11 arg ... ]
12 rksh [ ±abcefhikmnoprstuvxBCD ] [ -R file ] [ ±o option ] ... [ - ] [
13 arg ... ]
14
16 Ksh is a command and programming language that executes commands read
17 from a terminal or a file. Rksh is a restricted version of the command
18 interpreter ksh; it is used to set up login names and execution envi‐
19 ronments whose capabilities are more controlled than those of the stan‐
20 dard shell. Rpfksh is a profile shell version of the command inter‐
21 preter ksh; it is used to to execute commands with the attributes spec‐
22 ified by the user's profiles (see pfexec(1)). See Invocation below for
23 the meaning of arguments to the shell.
24 Definitions.
26 A metacharacter is one of the following characters:
27 ; & ( ) ⎪ < > new-line space tab
29 A blank is a tab or a space. An identifier is a sequence of letters,
31 digits, or underscores starting with a letter or underscore. Identi‐
32 fiers are used as components of variable names. A vname is a sequence
33 of one or more identifiers separated by a . and optionally preceded by
34 a .. Vnames are used as function and variable names. A word is a
35 sequence of characters from the character set defined by the current
36 locale, excluding non-quoted metacharacters.
37 A command is a sequence of characters in the syntax of the shell lan‐
39 guage. The shell reads each command and carries out the desired action
40 either directly or by invoking separate utilities. A built-in command
41 is a command that is carried out by the shell itself without creating a
42 separate process. Some commands are built-in purely for convenience
43 and are not documented here. Built-ins that cause side effects in the
44 shell environment and built-ins that are found before performing a path
45 search (see Execution below) are documented here. For historical rea‐
46 sons, some of these built-ins behave differently than other built-ins
47 and are called special built-ins.
48 Commands.
50 A simple-command is a list of variable assignments (see Variable
51 Assignments below) or a sequence of blank separated words which may be
52 preceded by a list of variable assignments (see Environment below).
53 The first word specifies the name of the command to be executed.
54 Except as specified below, the remaining words are passed as arguments
55 to the invoked command. The command name is passed as argument 0 (see
56 exec(2)). The value of a simple-command is its exit status; 0-255 if
57 it terminates normally; 256+signum if it terminates abnormally (the
58 name of the signal corresponding to the exit status can be obtained via
59 the -l option of the kill built-in utility).
60 A pipeline is a sequence of one or more commands separated by ⎪. The
62 standard output of each command but the last is connected by a pipe(2)
63 to the standard input of the next command. Each command, except possi‐
64 bly the last, is run as a separate process; the shell waits for the
65 last command to terminate. The exit status of a pipeline is the exit
66 status of the last command unless the pipefail option is enabled. Each
67 pipeline can be preceded by the reserved word ! which causes the exit
68 status of the pipeline to become 0 if the exit status of the last com‐
69 mand is non-zero, and 1 if the exit status of the last command is 0.
70 A list is a sequence of one or more pipelines separated by ;, &, ⎪&,
72 &&, or ⎪⎪, and optionally terminated by ;, &, or ⎪&. Of these five
73 symbols, ;, &, and ⎪& have equal precedence, which is lower than that
74 of && and ⎪⎪. The symbols && and ⎪⎪ also have equal precedence. A
75 semicolon (;) causes sequential execution of the preceding pipeline; an
76 ampersand (&) causes asynchronous execution of the preceding pipeline
77 (i.e., the shell does not wait for that pipeline to finish). The sym‐
78 bol ⎪& causes asynchronous execution of the preceding pipeline with a
79 two-way pipe established to the parent shell; the standard input and
80 output of the spawned pipeline can be written to and read from by the
81 parent shell by applying the redirection operators <& and >& with arg p
82 to commands and by using -p option of the built-in commands read and
83 print described later. The symbol && (⎪⎪) causes the list following it
84 to be executed only if the preceding pipeline returns a zero (non-zero)
85 value. One or more new-lines may appear in a list instead of a semi‐
86 colon, to delimit a command. The first item of the first pipeline of
87 a list that is a simple command not beginning with a redirection, and
88 not occurring within a while, until, or if list, can be preceded by a
89 semicolon. This semicolon is ignored unless the showme option is
90 enabled as described with the set built-in below.
91 A command is either a simple-command or one of the following. Unless
93 otherwise stated, the value returned by a command is that of the last
94 simple-command executed in the command.
95 for vname [ in word ... ] ;do list ;done
97 Each time a for command is executed, vname is set to the next
98 word taken from the in word list. If in word ... is omitted,
99 then the for command executes the do list once for each posi‐
100 tional parameter that is set starting from 1 (see Parameter
101 Expansion below). Execution ends when there are no more words
102 in the list.
103 for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
105 The arithmetic expression expr1 is evaluated first (see Arith‐
106 metic evaluation below). The arithmetic expression expr2 is
107 repeatedly evaluated until it evaluates to zero and when non-
108 zero, list is executed and the arithmetic expression expr3 eval‐
109 uated. If any expression is omitted, then it behaves as if it
110 evaluated to 1.
111 select vname [ in word ... ] ;do list ;done
113 A select command prints on standard error (file descriptor 2)
114 the set of words, each preceded by a number. If in word ... is
115 omitted, then the positional parameters starting from 1 are used
116 instead (see Parameter Expansion below). The PS3 prompt is
117 printed and a line is read from the standard input. If this
118 line consists of the number of one of the listed words, then the
119 value of the variable vname is set to the word corresponding to
120 this number. If this line is empty, the selection list is
121 printed again. Otherwise the value of the variable vname is set
122 to null. The contents of the line read from standard input is
123 saved in the variable REPLY. The list is executed for each
124 selection until a break or end-of-file is encountered. If the
125 REPLY variable is set to null by the execution of list, then the
126 selection list is printed before displaying the PS3 prompt for
127 the next selection.
128 case word in [ [(]pattern [ ⎪ pattern ] ... ) list ;; ] ... esac
130 A case command executes the list associated with the first pat‐
131 tern that matches word. The form of the patterns is the same as
132 that used for file-name generation (see File Name Generation
133 below). The ;; operator causes execution of case to terminate.
134 If ;& is used in place of ;; the next subsequent list, if any,
135 is executed.
136 if list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi
138 The list following if is executed and, if it returns a zero exit
139 status, the list following the first then is executed. Other‐
140 wise, the list following elif is executed and, if its value is
141 zero, the list following the next then is executed. Failing
142 each successive elif list, the else list is executed. If the if
143 list has non-zero exit status and there is no else list, then
144 the if command returns a zero exit status.
145 while list ;do list ;done
147 until list ;do list ;done
148 A while command repeatedly executes the while list and, if the
149 exit status of the last command in the list is zero, executes
150 the do list; otherwise the loop terminates. If no commands in
151 the do list are executed, then the while command returns a zero
152 exit status; until may be used in place of while to negate the
153 loop termination test.
154 ((expression))
156 The expression is evaluated using the rules for arithmetic eval‐
157 uation described below. If the value of the arithmetic expres‐
158 sion is non-zero, the exit status is 0, otherwise the exit sta‐
159 tus is 1.
160 (list)
162 Execute list in a separate environment. Note, that if two adja‐
163 cent open parentheses are needed for nesting, a space must be
164 inserted to avoid evaluation as an arithmetic command as
165 described above.
166 { list;}
168 list is simply executed. Note that unlike the metacharacters (
169 and ), { and } are reserved words and must occur at the begin‐
170 ning of a line or after a ; in order to be recognized.
171 [[ expression ]]
173 Evaluates expression and returns a zero exit status when expres‐
174 sion is true. See Conditional Expressions below, for a descrip‐
175 tion of expression.
176 function varname { list ;}
178 varname () { list ;}
179 Define a function which is referenced by varname. A function
180 whose varname contains a . is called a discipline function and
181 the portion of the varname preceding the last . must refer to
182 an existing variable. The body of the function is the list of
183 commands between { and }. A function defined with the function
184 varname syntax can also be used as an argument to the . special
185 built-in command to get the equivalent behavior as if the var‐
186 name() syntax were used to define it. (See Functions below.)
187 namespace identifier { list ;}
189 Defines or uses the name space identifier^ and runs the commands
190 in list^ in this name space. (See Name Spaces below.)
191 & [ name [ arg... ] ]
193 Causes subsequent list commands terminated by & to be placed in
194 the background job pool name. If name is omitted a default
195 unnamed pool is used. Commands in a named background pool may
196 be executed remotely.
197 time [ pipeline ]
199 If pipeline is omitted the user and system time for the current
200 shell and completed child processes is printed on standard
201 error. Otherwise, pipeline is executed and the elapsed time as
202 well as the user and system time are printed on standard error.
203 The TIMEFORMAT variable may be set to a format string that spec‐
204 ifies how the timing information should be displayed. See Shell
205 Variables below for a description of the TIMEFORMAT variable.
206 The following reserved words are recognized as reserved only when they
208 are the first word of a command and are not quoted:
209 if then else elif fi case esac for while until do done { } function
211 select time [[ ]] !
212 Variable Assignments.
214 One or more variable assignments can start a simple command or can be
215 arguments to the typeset, enum, export, or readonly special built-in
216 commands as well as to other declaration commands created as types.
217 The syntax for an assignment is of the form:
218 varname=word
220 varname[word]=word
221 No space is permitted between varname and the = or between = and
222 word.
223 varname=(assign_list)
225 No space is permitted between varname and the =. An assign_list
226 can be one of the following:
227 word ...
228 Indexed array assignment.
229 [word]=word ...
230 Associative array assignment. If preceded by
231 typeset -a this will create an indexed array
232 instead.
233 assignment ...
234 Compound variable assignment. This creates a
235 compound variable varname with sub-variables of
236 the form varname.name, where name is the name
237 portion of assignment. The value of varname will
238 contain all the assignment elements. Additional
239 assignments made to sub-variables of varname will
240 also be displayed as part of the value of var‐
241 name. If no assignments are specified, varname
242 will be a compound variable allowing subsequence
243 child elements to be defined.
244 typeset [options] assignment ...
245 Nested variable assignment. Multiple assignments
246 can be specified by separating each of them with
247 a ;. The previous value is unset before the
248 assignment. Other declaration commands such as
249 readonly, enum, and other declaration commands
250 can be used in place of typeset.
251 . filename
252 Include the assignment commands contained in
253 filename.
254 In addition, a += can be used in place of the = to signify adding to or
256 appending to the previous value. When += is applied to an arithmetic
257 type, word is evaluated as an arithmetic expression and added to the
258 current value. When applied to a string variable, the value defined by
259 word is appended to the value. For compound assignments, the previous
260 value is not unset and the new values are appended to the current ones
261 provided that the types are compatible.
262 The right hand side of a variable assignment undergoes all the expan‐
264 sion listed below except word splitting, brace expansion, and file name
265 generation. When the left hand side is an assignment is a compound
266 variable and the right hand is the name of a compound variable, the
267 compound variable on the right will be copied or appended to the com‐
268 pound variable on the left.
269 Comments.
271 A word beginning with # causes that word and all the following charac‐
272 ters up to a new-line to be ignored.
273 Aliasing.
274 The first word of each command is replaced by the text of an alias if
275 an alias for this word has been defined. An alias name consists of any
276 number of characters excluding metacharacters, quoting characters, file
277 expansion characters, parameter expansion and command substitution
278 characters, and =. The replacement string can contain any valid shell
279 script including the metacharacters listed above. The first word of
280 each command in the replaced text, other than any that are in the
281 process of being replaced, will be tested for aliases. If the last
282 character of the alias value is a blank then the word following the
283 alias will also be checked for alias substitution. Aliases can be used
284 to redefine built-in commands but cannot be used to redefine the
285 reserved words listed above. Aliases can be created and listed with
286 the alias command and can be removed with the unalias command.
287 Aliasing is performed when scripts are read, not while they are exe‐
288 cuted. Therefore, for an alias to take effect, the alias definition
289 command has to be executed before the command which references the
290 alias is read.
291 The following aliases are compiled into the shell but can be unset or
292 redefined:
293 autoload=′typeset -fu′
294 command=′command ′
295 compound=′typeset -C′
296 fc=hist
297 float=′typeset -lE′
298 functions=′typeset -f′
299 hash=′alias -t --′
300 history=′hist -l′
301 integer=′typeset -li′
302 nameref=′typeset -n′
303 nohup=′nohup ′
304 r=′hist -s′
305 redirect=′command exec′
306 source=′command .′
307 stop=′kill -s STOP′
308 suspend=′kill -s STOP $$′
309 times=′{ { time;} 2>&1;}′
310 type=′whence -v′
311 Tilde Substitution.
313 After alias substitution is performed, each word is checked to see if
314 it begins with an unquoted ∼. For tilde substitution, word also refers
315 to the word portion of parameter expansion (see Parameter Expansion
316 below). If it does, then the word up to a / is checked to see if it
317 matches a user name in the password database (See getpwname(3).) If a
318 match is found, the ∼ and the matched login name are replaced by the
319 login directory of the matched user. If no match is found, the origi‐
320 nal text is left unchanged. A ∼ by itself, or in front of a /, is
321 replaced by $HOME. A ∼ followed by a + or - is replaced by the value
322 of $PWD and $OLDPWD respectively.
323 In addition, when expanding a variable assignment, tilde substitution
325 is attempted when the value of the assignment begins with a ∼, and when
326 a ∼ appears after a :. The : also terminates a ∼ login name.
327 Command Substitution.
329 The standard output from a command list enclosed in parentheses pre‐
330 ceded by a dollar sign ( $(list) ), or in a brace group preceded by a
331 dollar sign ( ${ list;} ), or in a pair of grave accents (``) may be
332 used as part or all of a word; trailing new-lines are removed. In the
333 second case, the { and } are treated as a reserved words so that { must
334 be followed by a blank and } must appear at the beginning of the line
335 or follow a ;. In the third (obsolete) form, the string between the
336 quotes is processed for special quoting characters before the command
337 is executed (see Quoting below). The command substitution $(cat file)
338 can be replaced by the equivalent but faster $(<file). The command
339 substitution $(n<#) will expand to the current byte offset for file
340 descriptor n. Except for the second form, the command list is run in a
341 subshell so that no side effects are possible. For the second form,
342 the final } will be recognized as a reserved word after any token.
343 Arithmetic Substitution.
345 An arithmetic expression enclosed in double parentheses preceded by a
346 dollar sign ( $(()) ) is replaced by the value of the arithmetic
347 expression within the double parentheses.
348 Process Substitution.
350 Each command argument of the form <(list) or >(list) will run process
351 list asynchronously connected to some file in /dev/fd if this directory
352 exists, or else a fifo a temporary directory. The name of this file
353 will become the argument to the command. If the form with > is
354 selected then writing on this file will provide input for list. If <
355 is used, then the file passed as an argument will contain the output of
356 the list process. For example,
357 paste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1)
359 >(process2)
360 cuts fields 1 and 3 from the files file1 and file2 respectively, pastes
362 the results together, and sends it to the processes process1 and
363 process2, as well as putting it onto the standard output. Note that
364 the file, which is passed as an argument to the command, is a UNIX
365 pipe(2) so programs that expect to lseek(2) on the file will not work.
366 Process substitution of the form <(list) can also be used with the <
368 redirection operator which causes the output of list to be standard
369 input or the input for whatever file descriptor is specified.
370 Parameter Expansion.
372 A parameter is a variable, one or more digits, or any of the characters
373 ∗, @, #, ?, -, $, and !. A variable is denoted by a vname. To create
374 a variable whose vname contains a ., a variable whose vname consists of
375 everything before the last . must already exist. A variable has a
376 value and zero or more attributes. Variables can be assigned values
377 and attributes by using the typeset special built-in command. The
378 attributes supported by the shell are described later with the typeset
379 special built-in command. Exported variables pass values and
380 attributes to the environment.
381 The shell supports both indexed and associative arrays. An element of
383 an array variable is referenced by a subscript. A subscript for an
384 indexed array is denoted by an arithmetic expression (see Arithmetic
385 evaluation below) between a [ and a ]. To assign values to an indexed
386 array, use vname=(value ...) or set -A vname value ... . The value of
387 all non-negative subscripts must be in the range of 0 through
388 4,194,303. A negative subscript is treated as an offset from the maxi‐
389 mum current index +1 so that -1 refers to the last element. Indexed
390 arrays can be declared with the -a option to typeset. Indexed arrays
391 need not be declared. Any reference to a variable with a valid sub‐
392 script is legal and an array will be created if necessary.
393 An associative array is created with the -A option to typeset. A sub‐
395 script for an associative array is denoted by a string enclosed between
396 [ and ].
397 Referencing any array without a subscript is equivalent to referencing
399 the array with subscript 0.
400 The value of a variable may be assigned by writing:
402 vname=value [ vname=value ] ...
404 or
406 vname[subscript]=value [ vname[subscript]=value ] ...
407 Note that no space is allowed before or after the =.
408 A nameref is a variable that is a reference to another variable. A
409 nameref is created with the -n attribute of typeset. The value of the
410 variable at the time of the typeset command becomes the variable that
411 will be referenced whenever the nameref variable is used. The name of
412 a nameref cannot contain a .. When a variable or function name con‐
413 tains a ., and the portion of the name up to the first . matches the
414 name of a nameref, the variable referred to is obtained by replacing
415 the nameref portion with the name of the variable referenced by the
416 nameref. If a nameref is used as the index of a for loop, a name ref‐
417 erence is established for each item in the list. A nameref provides a
418 convenient way to refer to the variable inside a function whose name is
419 passed as an argument to a function. For example, if the name of a
420 variable is passed as the first argument to a function, the command
421 typeset -n var=$1
422 inside the function causes references and assignments to var to be ref‐
423 erences and assignments to the variable whose name has been passed to
424 the function.
425 If any of the floating point attributes, -E, -F, or -X, or the integer
426 attribute, -i, is set for vname, then the value is subject to arith‐
427 metic evaluation as described below.
428 Positional parameters, parameters denoted by a number, may be assigned
429 values with the set special built-in command. Parameter $0 is set from
430 argument zero when the shell is invoked.
431 The character $ is used to introduce substitutable parameters.
432 ${parameter}
433 The shell reads all the characters from ${ to the matching } as
434 part of the same word even if it contains braces or metacharac‐
435 ters. The value, if any, of the parameter is substituted. The
436 braces are required when parameter is followed by a letter,
437 digit, or underscore that is not to be interpreted as part of
438 its name, when the variable name contains a .. The braces are
439 also required when a variable is subscripted unless it is part
440 of an Arithmetic Expression or a Conditional Expression. If
441 parameter is one or more digits then it is a positional parame‐
442 ter. A positional parameter of more than one digit must be
443 enclosed in braces. If parameter is ∗ or @, then all the posi‐
444 tional parameters, starting with $1, are substituted (separated
445 by a field separator character). If an array vname with sub‐
446 script ∗ @, or of the form sub1 .. sub2. is used, then the
447 value for each of the elements between sub1 and sub2 inclusive
448 (or all elements for ∗ and @) is substituted, separated by the
449 first character of the value of IFS.
450 ${#parameter}
451 If parameter is ∗ or @, the number of positional parameters is
452 substituted. Otherwise, the length of the value of the parame‐
453 ter is substituted.
454 ${#vname[*]}
455 ${#vname[@]}
456 The number of elements in the array vname is substituted.
457 ${@vname}
459 Expands to the type name (See Type Variables below) or
460 attributes of the variable referred to by vname.
461 ${!vname}
462 Expands to the name of the variable referred to by vname. This
463 will be vname except when vname is a name reference.
464 ${!vname[subscript]}
465 Expands to name of the subscript unless subscript is *, @. or
466 of the form sub1 .. sub2. When subscript is *, the list of
467 array subscripts for vname is generated. For a variable that is
468 not an array, the value is 0 if the variable is set. Otherwise
469 it is null. When subscript is @, same as above, except that
470 when used in double quotes, each array subscript yields a sepa‐
471 rate argument. When subscript is of the form sub1 .. sub2 it
472 expands to the list of subscripts between sub1 and sub2 inclu‐
473 sive using the same quoting rules as @.
474 ${!prefix*}
475 Expands to the names of the variables whose names begin with
476 prefix.
477 ${parameter:-word}
478 If parameter is set and is non-null then substitute its value;
479 otherwise substitute word.
480 ${parameter:=word}
481 If parameter is not set or is null then set it to word; the
482 value of the parameter is then substituted. Positional parame‐
483 ters may not be assigned to in this way.
484 ${parameter:?word}
485 If parameter is set and is non-null then substitute its value;
486 otherwise, print word and exit from the shell (if not interac‐
487 tive). If word is omitted then a standard message is printed.
488 ${parameter:+word}
489 If parameter is set and is non-null then substitute word; other‐
490 wise substitute nothing.
491 In the above, word is not evaluated unless it is to be used as the sub‐
492 stituted string, so that, in the following example, pwd is executed
493 only if d is not set or is null:
494 print ${d:-$(pwd)}
495 If the colon ( : ) is omitted from the above expressions, then the
496 shell only checks whether parameter is set or not.
497 ${parameter:offset:length}
498 ${parameter:offset}
499 Expands to the portion of the value of parameter starting at the
500 character (counting from 0) determined by expanding offset as an
501 arithmetic expression and consisting of the number of characters
502 determined by the arithmetic expression defined by length. In
503 the second form, the remainder of the value is used. If A nega‐
504 tive offset counts backwards from the end of parameter. Note
505 that one or more blanks is required in front of a minus sign to
506 prevent the shell from interpreting the operator as :-. If
507 parameter is ∗ or @, or is an array name indexed by ∗ or @, then
508 offset and length refer to the array index and number of ele‐
509 ments respectively. A negative offset is taken relative to one
510 greater than the highest subscript for indexed arrays. The
511 order for associate arrays is unspecified.
512 ${parameter#pattern}
513 ${parameter##pattern}
514 If the shell pattern matches the beginning of the value of
515 parameter, then the value of this expansion is the value of the
516 parameter with the matched portion deleted; otherwise the value
517 of this parameter is substituted. In the first form the small‐
518 est matching pattern is deleted and in the second form the
519 largest matching pattern is deleted. When parameter is @, *, or
520 an array variable with subscript @ or *, the substring operation
521 is applied to each element in turn.
522 ${parameter%pattern}
524 ${parameter%%pattern}
525 If the shell pattern matches the end of the value of parameter,
526 then the value of this expansion is the value of the parameter
527 with the matched part deleted; otherwise substitute the value of
528 parameter. In the first form the smallest matching pattern is
529 deleted and in the second form the largest matching pattern is
530 deleted. When parameter is @, *, or an array variable with sub‐
531 script @ or *, the substring operation is applied to each ele‐
532 ment in turn.
533 ${parameter/pattern/string}
535 ${parameter//pattern/string}
536 ${parameter/#pattern/string}
537 ${parameter/%pattern/string}
538 Expands parameter and replaces the longest match of pattern with
539 the given string. Each occurrence of \n in string is replaced
540 by the portion of parameter that matches the n-th sub-pattern.
541 In the first form, only the first occurrence of pattern is
542 replaced. In the second form, each match for pattern is
543 replaced by the given string. The third form restricts the pat‐
544 tern match to the beginning of the string while the fourth form
545 restricts the pattern match to the end of the string. When
546 string is null, the pattern will be deleted and the / in front
547 of string may be omitted. When parameter is @, *, or an array
548 variable with subscript @ or *, the substitution operation is
549 applied to each element in turn. In this case, the string por‐
550 tion of word will be re-evaluated for each element.
551 The following parameters are automatically set by the shell:
553 # The number of positional parameters in decimal.
554 - Options supplied to the shell on invocation or by the set
555 command.
556 ? The decimal value returned by the last executed command.
557 $ The process number of this shell.
558 _ Initially, the value of _ is an absolute pathname of the
559 shell or script being executed as passed in the environ‐
560 ment. Subsequently it is assigned the last argument of
561 the previous command. This parameter is not set for com‐
562 mands which are asynchronous. This parameter is also
563 used to hold the name of the matching MAIL file when
564 checking for mail. While defining a compound variable or
565 a type, _ is initialized as a reference to the compound
566 variable or type. When a discipline function is invoked,
567 _ is initialized as a reference to the variable associ‐
568 ated with the call to this function. Finally when _ is
569 used as the name of the first variable of a type defini‐
570 tion, the new type is derived from the type of the first
571 variable (See Type Variables below.).
572 ! The process id or the pool name and job number of the
573 last background command invoked or the most recent job
574 put in the background with the bg built-in command.
575 Background jobs started in a named pool will be in the
576 form pool.number where pool is the pool name and number
577 is the job number within that pool.
578 .sh.command
579 When processing a DEBUG trap, this variable contains the
580 current command line that is about to run.
581 .sh.edchar
582 This variable contains the value of the keyboard charac‐
583 ter (or sequence of characters if the first character is
584 an ESC, ascii 033) that has been entered when processing
585 a KEYBD trap (see Key Bindings below). If the value is
586 changed as part of the trap action, then the new value
587 replaces the key (or key sequence) that caused the trap.
588 .sh.edcol
589 The character position of the cursor at the time of the
590 most recent KEYBD trap.
591 .sh.edmode
592 The value is set to ESC when processing a KEYBD trap
593 while in vi insert mode. (See Vi Editing Mode below.)
594 Otherwise, .sh.edmode is null when processing a KEYBD
595 trap.
596 .sh.edtext
597 The characters in the input buffer at the time of the
598 most recent KEYBD trap. The value is null when not pro‐
599 cessing a KEYBD trap.
600 .sh.file
601 The pathname of the file than contains the current com‐
602 mand.
603 .sh.fun
604 The name of the current function that is being executed.
605 .sh.level
606 Set to the current function depth. This can be changed
607 inside a DEBUG trap and will set the context to the spec‐
608 ified level.
609 .sh.lineno
610 Set during a DEBUG trap to the line number for the caller
611 of each function.
612 .sh.match
613 An indexed array which stores the most recent match and
614 sub-pattern matches after conditional pattern matches
615 that match and after variables expansions using the oper‐
616 ators #, %, or /. The 0-th element stores the complete
617 match and the i-th. element stores the i-th submatch.
618 The .sh.match variable becomes unset when the variable
619 that has expanded is assigned a new value.
620 .sh.math
621 Used for defining arithmetic functions (see Arithmetic
622 evaluation below). and stores the list of user defined
623 arithmetic functions.
624 .sh.name
625 Set to the name of the variable at the time that a disci‐
626 pline function is invoked.
627 .sh.subscript
628 Set to the name subscript of the variable at the time
629 that a discipline function is invoked.
630 .sh.subshell
631 The current depth for subshells and command substitution.
632 .sh.value
633 Set to the value of the variable at the time that the set
634 or append discipline function is invoked. When a user
635 defined arithmetic function is invoked, the value of
636 .sh.value is saved and .sh.value is set to long double
637 precission floating point. .sh.value is restored when
638 the function returns.
639 .sh.version
640 Set to a value that identifies the version of this shell.
641 KSH_VERSION
642 A name reference to .sh.version.
643 LINENO The current line number within the script or function
644 being executed.
645 OLDPWD The previous working directory set by the cd command.
646 OPTARG The value of the last option argument processed by the
647 getopts built-in command.
648 OPTIND The index of the last option argument processed by the
649 getopts built-in command.
650 PPID The process number of the parent of the shell.
651 PWD The present working directory set by the cd command.
652 RANDOM Each time this variable is referenced, a random integer,
653 uniformly distributed between 0 and 32767, is generated.
654 The sequence of random numbers can be initialized by
655 assigning a numeric value to RANDOM.
656 REPLY This variable is set by the select statement and by the
657 read built-in command when no arguments are supplied.
658 SECONDS
659 Each time this variable is referenced, the number of sec‐
660 onds since shell invocation is returned. If this vari‐
661 able is assigned a value, then the value returned upon
662 reference will be the value that was assigned plus the
663 number of seconds since the assignment.
664 SHLVL An integer variable the is incremented each time the
665 shell is invoked and is exported. If SHLVL is not in the
666 environment when the shell is invoked, it is set to 1.
667 The following variables are used by the shell:
669 CDPATH The search path for the cd command.
670 COLUMNS
671 If this variable is set, the value is used to define the
672 width of the edit window for the shell edit modes and for
673 printing select lists.
674 EDITOR If the VISUAL variable is not set, the value of this
675 variable will be checked for the patterns as described
676 with VISUAL below and the corresponding editing option
677 (see Special Command set below) will be turned on.
678 ENV If this variable is set, then parameter expansion, com‐
679 mand substitution, and arithmetic substitution are per‐
680 formed on the value to generate the pathname of the
681 script that will be executed when the shell is invoked
682 interactively (see Invocation below). This file is typi‐
683 cally used for alias and function definitions. The
684 default value is $HOME/.kshrc. On systems that support a
685 system wide /etc/ksh.kshrc initialization file, if the
686 filename generated by the expansion of ENV begins with
687 /./ or ././ the system wide initialization file will not
688 be executed.
689 FCEDIT Obsolete name for the default editor name for the hist
690 command. FCEDIT is not used when HISTEDIT is set.
691 FIGNORE
692 A pattern that defines the set of filenames that will be
693 ignored when performing filename matching.
694 FPATH The search path for function definitions. The directo‐
695 ries in this path are searched for a file with the same
696 name as the function or command when a function with the
697 -u attribute is referenced and when a command is not
698 found. If an executable file with the name of that com‐
699 mand is found, then it is read and executed in the cur‐
700 rent environment. Unlike PATH, the current directory
701 must be represented explicitly by . rather than by adja‐
702 cent : characters or a beginning or ending :.
703 HISTCMD
704 Number of the current command in the history file.
705 HISTEDIT
706 Name for the default editor name for the hist command.
707 HISTFILE
708 If this variable is set when the shell is invoked, then
709 the value is the pathname of the file that will be used
710 to store the command history (see Command Re-entry
711 below).
712 HISTSIZE
713 If this variable is set when the shell is invoked, then
714 the number of previously entered commands that are acces‐
715 sible by this shell will be greater than or equal to this
716 number. The default is 512.
717 HOME The default argument (home directory) for the cd command.
718 IFS Internal field separators, normally space, tab, and new-
719 line that are used to separate the results of command
720 substitution or parameter expansion and to separate
721 fields with the built-in command read. The first charac‐
722 ter of the IFS variable is used to separate arguments for
723 the "$∗" substitution (see Quoting below). Each single
724 occurrence of an IFS character in the string to be split,
725 that is not in the isspace character class, and any adja‐
726 cent characters in IFS that are in the isspace character
727 class, delimit a field. One or more characters in IFS
728 that belong to the isspace character class, delimit a
729 field. In addition, if the same isspace character
730 appears consecutively inside IFS, this character is
731 treated as if it were not in the isspace class, so that
732 if IFS consists of two tab characters, then two adjacent
733 tab characters delimit a null field.
734 JOBMAX This variable defines the maximum number running back‐
735 ground jobs that can run at a time. When this limit is
736 reached, the shell will wait for a job to complete before
737 staring a new job.
738 LANG This variable determines the locale category for any cat‐
739 egory not specifically selected with a variable starting
740 with LC_ or LANG.
741 LC_ALL This variable overrides the value of the LANG variable
742 and any other LC_ variable.
743 LC_COLLATE
744 This variable determines the locale category for charac‐
745 ter collation information.
746 LC_CTYPE
747 This variable determines the locale category for charac‐
748 ter handling functions. It determines the character
749 classes for pattern matching (see File Name Generation
750 below).
751 LC_NUMERIC
752 This variable determines the locale category for the dec‐
753 imal point character.
754 LINES If this variable is set, the value is used to determine
755 the column length for printing select lists. Select
756 lists will print vertically until about two-thirds of
757 LINES lines are filled.
758 MAIL If this variable is set to the name of a mail file and
759 the MAILPATH variable is not set, then the shell informs
760 the user of arrival of mail in the specified file.
761 MAILCHECK
762 This variable specifies how often (in seconds) the shell
763 will check for changes in the modification time of any of
764 the files specified by the MAILPATH or MAIL variables.
765 The default value is 600 seconds. When the time has
766 elapsed the shell will check before issuing the next
767 prompt.
768 MAILPATH
769 A colon ( : ) separated list of file names. If this
770 variable is set, then the shell informs the user of any
771 modifications to the specified files that have occurred
772 within the last MAILCHECK seconds. Each file name can be
773 followed by a ? and a message that will be printed. The
774 message will undergo parameter expansion, command substi‐
775 tution, and arithmetic substitution with the variable $_
776 defined as the name of the file that has changed. The
777 default message is you have mail in $_.
778 PATH The search path for commands (see Execution below). The
779 user may not change PATH if executing under rksh (except
780 in .profile).
781 PS1 The value of this variable is expanded for parameter
782 expansion, command substitution, and arithmetic substitu‐
783 tion to define the primary prompt string which by default
784 is ``$''. The character ! in the primary prompt string
785 is replaced by the command number (see Command Re-entry
786 below). Two successive occurrences of ! will produce a
787 single ! when the prompt string is printed.
788 PS2 Secondary prompt string, by default ``> ''.
789 PS3 Selection prompt string used within a select loop, by
790 default ``#? ''.
791 PS4 The value of this variable is expanded for parameter
792 evaluation, command substitution, and arithmetic substi‐
793 tution and precedes each line of an execution trace. By
794 default, PS4 is ``+ ''. In addition when PS4 is unset,
795 the execution trace prompt is also ``+ ''.
796 SHELL The pathname of the shell is kept in the environment. At
797 invocation, if the basename of this variable is rsh,
798 rksh, or krsh, then the shell becomes restricted. If it
799 is pfsh or pfksh, then the shell becomes a profile shell
800 (see pfexec(1)).
801 TIMEFORMAT
802 The value of this parameter is used as a format string
803 specifying how the timing information for pipelines pre‐
804 fixed with the time reserved word should be displayed.
805 The % character introduces a format sequence that is
806 expanded to a time value or other information. The for‐
807 mat sequences and their meanings are as follows.
808 %% A literal %.
809 %[p][l]R The elapsed time in seconds.
810 %[p][l]U The number of CPU seconds spent in user mode.
811 %[p][l]S The number of CPU seconds spent in system mode.
812 %P The CPU percentage, computed as (U + S) / R.
813 The brackets denote optional portions. The optional p is
815 a digit specifying the precision, the number of frac‐
816 tional digits after a decimal point. A value of 0 causes
817 no decimal point or fraction to be output. At most three
818 places after the decimal point can be displayed; values
819 of p greater than 3 are treated as 3. If p is not speci‐
820 fied, the value 3 is used.
821 The optional l specifies a longer format, including hours
823 if greater than zero, minutes, and seconds of the form
824 HHhMMmSS.FFs. The value of p determines whether or not
825 the fraction is included.
826 All other characters are output without change and a
828 trailing newline is added. If unset, the default value,
829 $'\nreal\t%2lR\nuser\t%2lU\nsys%2lS', is used. If the
830 value is null, no timing information is displayed.
831 TMOUT If set to a value greater than zero, TMOUT will be the
833 default timeout value for the read built-in command. The
834 select compound command terminates after TMOUT seconds
835 when input is from a terminal. Otherwise, the shell will
836 terminate if a line is not entered within the prescribed
837 number of seconds while reading from a terminal. (Note
838 that the shell can be compiled with a maximum bound for
839 this value which cannot be exceeded.)
840 VISUAL If the value of this variable matches the pattern
842 *[Vv][Ii]*, then the vi option (see Special Command set
843 below) is turned on. If the value matches the pattern
844 *gmacs* , the gmacs option is turned on. If the value
845 matches the pattern *macs*, then the emacs option will be
846 turned on. The value of VISUAL overrides the value of
847 EDITOR.
848 The shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK,
850 FCEDIT, TMOUT and IFS, while HOME, SHELL, ENV, and MAIL are not set at
851 all by the shell (although HOME is set by login(1)). On some systems
852 MAIL and SHELL are also set by login(1).
853 Field Splitting.
855 After parameter expansion and command substitution, the results of sub‐
856 stitutions are scanned for the field separator characters (those found
857 in IFS) and split into distinct fields where such characters are found.
858 Explicit null fields ("" or ′′) are retained. Implicit null fields
859 (those resulting from parameters that have no values or command substi‐
860 tutions with no output) are removed.
861 If the braceexpand (-B) option is set then each of the fields resulting
863 from IFS are checked to see if they contain one or more of the brace
864 patterns {*,*}, {l1..l2} , {n1..n2} , {n1..n2% fmt} , {n1..n2 ..n3} ,
865 or {n1..n2 ..n3%fmt} , where * represents any character, l1,l2 are let‐
866 ters and n1,n2,n3 are signed numbers and fmt is a format specified as
867 used by printf. In each case, fields are created by prepending the
868 characters before the { and appending the characters after the } to
869 each of the strings generated by the characters between the { and }.
870 The resulting fields are checked to see if they have any brace pat‐
871 terns.
872 In the first form, a field is created for each string between { and ,,
874 between , and ,, and between , and }. The string represented by * can
875 contain embedded matching { and } without quoting. Otherwise, each {
876 and } with * must be quoted.
877 In the seconds form, l1 and l2 must both be either upper case or both
879 be lower case characters in the C locale. In this case a field is cre‐
880 ated for each character from l1 thru l2.
881 In the remaining forms, a field is created for each number starting at
883 n1 and continuing until it reaches n2 incrementing n1 by n3. The cases
884 where n3 is not specified behave as if n3 where 1 if n1<=n2 and -1 oth‐
885 erwise. If forms which specify %fmt any format flags, widths and pre‐
886 cisions can be specified and fmt can end in any of the specifiers
887 cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to the 8
888 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx, z04bx and z4cx.
889 File Name Generation.
891 Following splitting, each field is scanned for the characters ∗, ?, (,
892 and [ unless the -f option has been set. If one of these characters
893 appears, then the word is regarded as a pattern. Each file name compo‐
894 nent that contains any pattern character is replaced with a lexico‐
895 graphically sorted set of names that matches the pattern from that
896 directory. If no file name is found that matches the pattern, then
897 that component of the filename is left unchanged unless the pattern is
898 prefixed with ∼(N) in which case it is removed as described below. If
899 FIGNORE is set, then each file name component that matches the pattern
900 defined by the value of FIGNORE is ignored when generating the matching
901 filenames. The names . and .. are also ignored. If FIGNORE is not
902 set, the character . at the start of each file name component will be
903 ignored unless the first character of the pattern corresponding to this
904 component is the character . itself. Note, that for other uses of
905 pattern matching the / and . are not treated specially.
906 ∗ Matches any string, including the null string. When used
908 for filename expansion, if the globstar option is on, two
909 adjacent ∗'s by itself will match all files and zero or
910 more directories and subdirectories. If followed by a /
911 then only directories and subdirectories will match.
912 ? Matches any single character.
913 [...] Matches any one of the enclosed characters. A pair of
914 characters separated by - matches any character lexically
915 between the pair, inclusive. If the first character fol‐
916 lowing the opening [ is a ! or ^ then any character not
917 enclosed is matched. A - can be included in the charac‐
918 ter set by putting it as the first or last character.
919 Within [ and ], character classes can be specified with
920 the syntax [:class:] where class is one of the following
921 classes defined in the ANSI-C standard: (Note that word
922 is equivalent to alnum plus the character _.)
923 alnum alpha blank cntrl digit graph lower print punct
924 space upper word xdigit
925 Within [ and ], an equivalence class can be specified
926 with the syntax [=c=] which matches all characters with
927 the same primary collation weight (as defined by the cur‐
928 rent locale) as the character c. Within [ and ], [.sym‐
929 bol.] matches the collating symbol symbol.
930 A pattern-list is a list of one or more patterns separated from each
931 other with a & or ⎪. A & signifies that all patterns must be matched
932 whereas ⎪ requires that only one pattern be matched. Composite pat‐
933 terns can be formed with one or more of the following sub-patterns:
934 ?(pattern-list)
935 Optionally matches any one of the given patterns.
936 *(pattern-list)
937 Matches zero or more occurrences of the given patterns.
938 +(pattern-list)
939 Matches one or more occurrences of the given patterns.
940 {n}(pattern-list)
941 Matches n occurrences of the given patterns.
942 {m,n}(pattern-list)
943 Matches from m to n occurrences of the given patterns.
944 If m is omitted, 0 will be used. If n is omitted at
945 least m occurrences will be matched.
946 @(pattern-list)
947 Matches exactly one of the given patterns.
948 !(pattern-list)
949 Matches anything except one of the given patterns.
950 By default, each pattern, or sub-pattern will match the longest string
951 possible consistent with generating the longest overall match. If more
952 than one match is possible, the one starting closest to the beginning
953 of the string will be chosen. However, for each of the above compound
954 patterns a - can be inserted in front of the ( to cause the shortest
955 match to the specified pattern-list to be used.
956 When pattern-list is contained within parentheses, the backslash char‐
958 acter \ is treated specially even when inside a character class. All
959 ANSI-C character escapes are recognized and match the specified charac‐
960 ter. In addition the following escape sequences are recognized:
961 \d Matches any character in the digit class.
962 \D Matches any character not in the digit class.
963 \s Matches any character in the space class.
964 \S Matches any character not in the space class.
965 \w Matches any character in the word class.
966 \W Matches any character not in the word class.
967 A pattern of the form %(pattern-pair(s)) is a sub-pattern that can be
969 used to match nested character expressions. Each pattern-pair is a two
970 character sequence which cannot contain & or ⎪. The first pattern-pair
971 specifies the starting and ending characters for the match. Each sub‐
972 sequent pattern-pair represents the beginning and ending characters of
973 a nested group that will be skipped over when counting starting and
974 ending character matches. The behavior is unspecified when the first
975 character of a pattern-pair is alpha-numeric except for the following:
976 D Causes the ending character to terminate the search for
977 this pattern without finding a match.
978 E Causes the ending character to be interpreted as an
979 escape character.
980 L Causes the ending character to be interpreted as a quote
981 character causing all characters to be ignored when look‐
982 ing for a match.
983 Q Causes the ending character to be interpreted as a quote
984 character causing all characters other than any escape
985 character to be ignored when looking for a match.
986 Thus, %({}Q"E\), matches characters starting at { until the matching }
987 is found not counting any { or } that is inside a double quoted string
988 or preceded by the escape character \. Without the {} this pattern
989 matches any C language string.
990 Each sub-pattern in a composite pattern is numbered, starting at 1, by
992 the location of the ( within the pattern. The sequence \n, where n is
993 a single digit and \n comes after the n-th. sub-pattern, matches the
994 same string as the sub-pattern itself.
995 Finally a pattern can contain sub-patterns of the form ∼(options:pat‐
997 tern-list), where either options or :pattern-list can be omitted.
998 Unlike the other compound patterns, these sub-patterns are not counted
999 in the numbered sub-patterns. :pattern-list must be omitted for the
1000 upper-case options below. If options is present, it can consist of one
1001 or more of the following:
1002 + Enable the following options. This is the default.
1003 - Disable the following options.
1004 E The remainder of the pattern uses extended regular
1005 expression syntax like the egrep(1) command.
1006 F The remainder of the pattern uses fgrep(1) expression
1007 syntax.
1008 G The remainder of the pattern uses basic regular expres‐
1009 sion syntax like the grep(1) command.
1010 K The remainder of the pattern uses shell pattern syntax.
1011 This is the default.
1012 N This is ignored. However, when it is the first letter
1013 and is used with file name generation, and no matches
1014 occur, the file pattern expands to the empty string.
1015 X The remainder of the pattern uses augmented regular
1016 expression syntax like the xgrep(1) command.
1017 i Treat the match as case insensitive.
1018 g File the longest match (greedy). This is the default.
1019 l Left anchor the pattern. This is the default for K style
1020 patterns.
1021 r Right anchor the pattern. This is the default for K
1022 style patterns.
1023 If both options and :pattern-list are specified, then the options apply
1024 only to pattern-list. Otherwise, these options remain in effect until
1025 they are disabled by a subsequent ∼(...) or at the end of the sub-pat‐
1026 tern containing ∼(...).
1027 Quoting.
1029 Each of the metacharacters listed earlier (see Definitions above) has a
1030 special meaning to the shell and causes termination of a word unless
1031 quoted. A character may be quoted (i.e., made to stand for itself) by
1032 preceding it with a \. The pair \new-line is removed. All characters
1033 enclosed between a pair of single quote marks (′′) that is not preceded
1034 by a $ are quoted. A single quote cannot appear within the single
1035 quotes. A single quoted string preceded by an unquoted $ is processed
1036 as an ANSI-C string except for the following:
1037 \0 Causes the remainder of the string to be ignored.
1038 \E Equivalent to the escape character (ascii 033),
1039 \e Equivalent to the escape character (ascii 033),
1040 \cx Expands to the character control-x.
1041 \C[.name.]
1042 Expands to the collating element name.
1043 Inside double quote marks (""), parameter and command substitution
1045 occur and \ quotes the characters \, `, ", and $. A $ in front of a
1046 double quoted string will be ignored in the "C" or "POSIX" locale, and
1047 may cause the string to be replaced by a locale specific string other‐
1048 wise. The meaning of $∗ and $@ is identical when not quoted or when
1049 used as a variable assignment value or as a file name. However, when
1050 used as a command argument, "$∗" is equivalent to "$1d$2d...", where d
1051 is the first character of the IFS variable, whereas "$@" is equivalent
1052 to "$1" "$2" .... Inside grave quote marks (``), \ quotes the charac‐
1053 ters \, `, and $. If the grave quotes occur within double quotes, then
1054 \ also quotes the character ".
1055 The special meaning of reserved words or aliases can be removed by
1057 quoting any character of the reserved word. The recognition of func‐
1058 tion names or built-in command names listed below cannot be altered by
1059 quoting them.
1060 Arithmetic Evaluation.
1062 The shell performs arithmetic evaluation for arithmetic substitution,
1063 to evaluate an arithmetic command, to evaluate an indexed array sub‐
1064 script, and to evaluate arguments to the built-in commands shift and
1065 let. Evaluations are performed using double precision floating point
1066 arithmetic or long double precision floating point for systems that
1067 provide this data type. Floating point constants follow the ANSI-C
1068 programming language floating point conventions. Integer constants
1069 follow the ANSI-C programming language integer constant conventions
1070 although only single byte character constants are recognized and char‐
1071 acter casts are not recognized. In addition constants can be of the
1072 form [base#]n where base is a decimal number between two and sixty-four
1073 representing the arithmetic base and n is a number in that base. The
1074 digits above 9 are represented by the lower case letters, the upper
1075 case letters, @, and _ respectively. For bases less than or equal to
1076 36, upper and lower case characters can be used interchangeably.
1077 An arithmetic expression uses the same syntax, precedence, and associa‐
1079 tivity of expression as the C language. All the C language operators
1080 that apply to floating point quantities can be used. In addition, the
1081 operator ** can be used for exponentiation. It has higher precedence
1082 than multiplication and is left associative. In addition, when the
1083 value of an arithmetic variable or sub-expression can be represented as
1084 a long integer, all C language integer arithmetic operations can be
1085 performed. Variables can be referenced by name within an arithmetic
1086 expression without using the parameter expansion syntax. When a vari‐
1087 able is referenced, its value is evaluated as an arithmetic expression.
1088 Any of the following math library functions that are in the C math
1090 library can be used within an arithmetic expression:
1091 abs acos acosh asin asinh atan atan2 atanh cbrt copysign cos cosh erf
1093 erfc exp exp2 expm1 fabs fdim finite floor fma fmax fmin fmod hypot
1094 ilogb int isinf isnan j0 j1 jn lgamma log log2 logb nearbyint nextafter
1095 nexttoward pow remainder rint round sin sinh sqrt tan tanh tgamma trunc
1096 y0 y1 yn In addition, arithmetic functions can be define as shell func‐
1097 tions with a variant of the function name syntax,
1098 function .sh.math.name ident ... { list ;}
1100 where name is the function name used in the arithmetic expres‐
1101 sion and each identifier, ident is a name reference to the long
1102 double precission floating point argument. The value of
1103 .sh.value when the function returns is the value of this func‐
1104 tion. User defined functions can take up to 3 arguments and
1105 override C math library functions.
1106 An internal representation of a variable as a double precision floating
1108 point can be specified with the -E [n], -F [n], or -X [n] option of the
1109 typeset special built-in command. The -E option causes the expansion
1110 of the value to be represented using scientific notation when it is
1111 expanded. The optional option argument n defines the number of signif‐
1112 icant figures. The -F option causes the expansion to be represented as
1113 a floating decimal number when it is expanded. The -X option cause the
1114 expansion to be represented using the %a format defined by ISO C-99.
1115 The optional option argument n defines the number of places after the
1116 decimal (or radix) point in this case.
1117 An internal integer representation of a variable can be specified with
1119 the -i [n] option of the typeset special built-in command. The
1120 optional option argument n specifies an arithmetic base to be used when
1121 expanding the variable. If you do not specify an arithmetic base, base
1122 10 will be used.
1123 Arithmetic evaluation is performed on the value of each assignment to a
1125 variable with the -E, -F, -X, or -i attribute. Assigning a floating
1126 point number to a variable whose type is an integer causes the frac‐
1127 tional part to be truncated.
1128 Prompting.
1130 When used interactively, the shell prompts with the value of PS1 after
1131 expanding it for parameter expansion, command substitution, and arith‐
1132 metic substitution, before reading a command. In addition, each single
1133 ! in the prompt is replaced by the command number. A !! is required
1134 to place ! in the prompt. If at any time a new-line is typed and fur‐
1135 ther input is needed to complete a command, then the secondary prompt
1136 (i.e., the value of PS2) is issued.
1137 Conditional Expressions.
1139 A conditional expression is used with the [[ compound command to test
1140 attributes of files and to compare strings. Field splitting and file
1141 name generation are not performed on the words between [[ and ]]. Each
1142 expression can be constructed from one or more of the following unary
1143 or binary expressions:
1144 string True, if string is not null.
1145 -a file
1146 Same as -e below. This is obsolete.
1147 -b file
1148 True, if file exists and is a block special file.
1149 -c file
1150 True, if file exists and is a character special file.
1151 -d file
1152 True, if file exists and is a directory.
1153 -e file
1154 True, if file exists.
1155 -f file
1156 True, if file exists and is an ordinary file.
1157 -g file
1158 True, if file exists and it has its setgid bit set.
1159 -k file
1160 True, if file exists and it has its sticky bit set.
1161 -n string
1162 True, if length of string is non-zero.
1163 -o ?option
1164 True, if option named option is a valid option name.
1165 -o option
1166 True, if option named option is on.
1167 -p file
1168 True, if file exists and is a fifo special file or a pipe.
1169 -r file
1170 True, if file exists and is readable by current process.
1171 -s file
1172 True, if file exists and has size greater than zero.
1173 -t fildes
1174 True, if file descriptor number fildes is open and associated
1175 with a terminal device.
1176 -u file
1177 True, if file exists and it has its setuid bit set.
1178 -w file
1179 True, if file exists and is writable by current process.
1180 -x file
1181 True, if file exists and is executable by current process. If
1182 file exists and is a directory, then true if the current process
1183 has permission to search in the directory.
1184 -z string
1185 True, if length of string is zero.
1186 -L file
1187 True, if file exists and is a symbolic link.
1188 -h file
1189 True, if file exists and is a symbolic link.
1190 -N file
1191 True, if file exists and the modification time is greater than
1192 the last access time.
1193 -O file
1194 True, if file exists and is owned by the effective user id of
1195 this process.
1196 -G file
1197 True, if file exists and its group matches the effective group
1198 id of this process.
1199 -S file
1200 True, if file exists and is a socket.
1201 file1 -nt file2
1202 True, if file1 exists and file2 does not, or file1 is newer than
1203 file2.
1204 file1 -ot file2
1205 True, if file2 exists and file1 does not, or file1 is older than
1206 file2.
1207 file1 -ef file2
1208 True, if file1 and file2 exist and refer to the same file.
1209 string == pattern
1210 True, if string matches pattern. Any part of pattern can be
1211 quoted to cause it to be matched as a string. With a successful
1212 match to a pattern, the .sh.match array variable will contain
1213 the match and sub-pattern matches.
1214 string = pattern
1215 Same as == above, but is obsolete.
1216 string != pattern
1217 True, if string does not match pattern. When the string matches
1218 the pattern the .sh.match array variable will contain the match
1219 and sub-pattern matches.
1220 string =∼ ere
1221 True if string matches the pattern ∼(E)ere where ere is an
1222 extended regular expression.
1223 string1 < string2
1224 True, if string1 comes before string2 based on ASCII value of
1225 their characters.
1226 string1 > string2
1227 True, if string1 comes after string2 based on ASCII value of
1228 their characters.
1229 The following obsolete arithmetic comparisons are also permitted:
1230 exp1 -eq exp2
1231 True, if exp1 is equal to exp2.
1232 exp1 -ne exp2
1233 True, if exp1 is not equal to exp2.
1234 exp1 -lt exp2
1235 True, if exp1 is less than exp2.
1236 exp1 -gt exp2
1237 True, if exp1 is greater than exp2.
1238 exp1 -le exp2
1239 True, if exp1 is less than or equal to exp2.
1240 exp1 -ge exp2
1241 True, if exp1 is greater than or equal to exp2.
1242 In each of the above expressions, if file is of the form /dev/fd/n,
1244 where n is an integer, then the test is applied to the open file whose
1245 descriptor number is n.
1246 A compound expression can be constructed from these primitives by using
1248 any of the following, listed in decreasing order of precedence.
1249 (expression)
1250 True, if expression is true. Used to group expressions.
1251 ! expression
1252 True if expression is false.
1253 expression1 && expression2
1254 True, if expression1 and expression2 are both true.
1255 expression1 ⎪⎪ expression2
1256 True, if either expression1 or expression2 is true.
1257 Input/Output.
1259 Before a command is executed, its input and output may be redirected
1260 using a special notation interpreted by the shell. The following may
1261 appear anywhere in a simple-command or may precede or follow a command
1262 and are not passed on to the invoked command. Command substitution,
1263 parameter expansion, and arithmetic substitution occur before word or
1264 digit is used except as noted below. File name generation occurs only
1265 if the shell is interactive and the pattern matches a single file.
1266 Field splitting is not performed.
1267 In each of the following redirections, if file is of the form
1269 /dev/sctp/host/port, /dev/tcp/host/port, or /dev/udp/host/port, where
1270 host is a hostname or host address, and port is a service given by name
1271 or an integer port number, then the redirection attempts to make a tcp,
1272 sctp or udp connection to the corresponding socket.
1273 No intervening space is allowed between the characters of redirection
1275 operators.
1276 <word Use file word as standard input (file descriptor 0).
1278 >word Use file word as standard output (file descriptor 1). If
1280 the file does not exist then it is created. If the file
1281 exists, and the noclobber option is on, this causes an
1282 error; otherwise, it is truncated to zero length.
1283 >|word Sames as >, except that it overrides the noclobber
1285 option.
1286 >;word Write output to a temporary file. If the command com‐
1288 pletes successfully rename it to word, otherwise, delete
1289 the temporary file. >;word cannot be used with the
1290 exec(2). built-in.
1291 >>word Use file word as standard output. If the file exists,
1293 then output is appended to it (by first seeking to the
1294 end-of-file); otherwise, the file is created.
1295 <>word Open file word for reading and writing as standard out‐
1297 put.
1298 <>;word The same as <>word except that if the command completes
1300 successfully, word is truncated to the offset at command
1301 completion. <>;word cannot be used with the exec(2).
1302 built-in.
1303 <<[-]word The shell input is read up to a line that is the same as
1305 word after any quoting has been removed, or to an end-of-
1306 file. No parameter substitution, command substitution,
1307 arithmetic substitution or file name generation is per‐
1308 formed on word. The resulting document, called a here-
1309 document, becomes the standard input. If any character
1310 of word is quoted, then no interpretation is placed upon
1311 the characters of the document; otherwise, parameter
1312 expansion, command substitution, and arithmetic substitu‐
1313 tion occur, \new-line is ignored, and \ must be used to
1314 quote the characters \, $, `. If - is appended to <<,
1315 then all leading tabs are stripped from word and from the
1316 document. If # is appended to <<, then leading spaces
1317 and tabs will be stripped off the first line of the docu‐
1318 ment and up to an equivalent indentation will be stripped
1319 from the remaining lines and from word. A tab stop is
1320 assumed to occur at every 8 columns for the purposes of
1321 determining the indentation.
1322 <<<word A short form of here document in which word becomes the
1324 contents of the here-document after any parameter expan‐
1325 sion, command substitution, and arithmetic substitution
1326 occur.
1327 <&digit The standard input is duplicated from file descriptor
1329 digit (see dup(2)). Similarly for the standard output
1330 using >&digit.
1331 <&digit- The file descriptor given by digit is moved to standard
1333 input. Similarly for the standard output using >&digit-.
1334 <&- The standard input is closed. Similarly for the standard
1336 output using >&-.
1337 <&p The input from the co-process is moved to standard input.
1339 >&p The output to the co-process is moved to standard output.
1341 <#((expr)) Evaluate arithmetic expression expr and position file
1343 descriptor 0 to the resulting value bytes from the start
1344 of the file. The variables CUR and EOF evaluate to the
1345 current offset and end-of-file offset respectively when
1346 evaluating expr.
1347 >#((offset)) The same as <# except applies to file descriptor 1.
1349 <#pattern Seeks forward to the beginning of the next line contain‐
1351 ing pattern.
1352 <##pattern The same as <# except that the portion of the file that
1354 is skipped is copied to standard output.
1355 If one of the above is preceded by a digit, with no intervening space,
1357 then the file descriptor number referred to is that specified by the
1358 digit (instead of the default 0 or 1). If one of the above, other than
1359 >&- and the ># and <# forms, is preceded by {varname} with no interven‐
1360 ing space, then a file descriptor number > 10 will be selected by the
1361 shell and stored in the variable varname. If >&- or the any of the >#
1362 and <# forms is preceded by {varname} the value of varname defines the
1363 file descriptor to close or position. For example:
1364 ... 2>&1
1366 means file descriptor 2 is to be opened for writing as a duplicate of
1368 file descriptor 1 and
1369 exec {n}<file
1371 means open file named file for reading and store the file descriptor
1373 number in variable n.
1374 The order in which redirections are specified is significant. The
1376 shell evaluates each redirection in terms of the (file descriptor,
1377 file) association at the time of evaluation. For example:
1378 ... 1>fname 2>&1
1380 first associates file descriptor 1 with file fname. It then associates
1382 file descriptor 2 with the file associated with file descriptor 1 (i.e.
1383 fname). If the order of redirections were reversed, file descriptor 2
1384 would be associated with the terminal (assuming file descriptor 1 had
1385 been) and then file descriptor 1 would be associated with file fname.
1386 If a command is followed by & and job control is not active, then the
1388 default standard input for the command is the empty file /dev/null.
1389 Otherwise, the environment for the execution of a command contains the
1390 file descriptors of the invoking shell as modified by input/output
1391 specifications.
1392 Environment.
1394 The environment (see environ(7)) is a list of name-value pairs that is
1395 passed to an executed program in the same way as a normal argument
1396 list. The names must be identifiers and the values are character
1397 strings. The shell interacts with the environment in several ways. On
1398 invocation, the shell scans the environment and creates a variable for
1399 each name found, giving it the corresponding value and attributes and
1400 marking it export. Executed commands inherit the environment. If the
1401 user modifies the values of these variables or creates new ones, using
1402 the export or typeset -x commands, they become part of the environment.
1403 The environment seen by any executed command is thus composed of any
1404 name-value pairs originally inherited by the shell, whose values may be
1405 modified by the current shell, plus any additions which must be noted
1406 in export or typeset -x commands.
1407 The environment for any simple-command or function may be augmented by
1409 prefixing it with one or more variable assignments. A variable assign‐
1410 ment argument is a word of the form identifier=value. Thus:
1411 TERM=450 cmd args and
1413 (export TERM; TERM=450; cmd args)
1414 are equivalent (as far as the above execution of cmd is concerned
1416 except for special built-in commands listed below - those that are pre‐
1417 ceded with a dagger).
1418 If the obsolete -k option is set, all variable assignment arguments are
1420 placed in the environment, even if they occur after the command name.
1421 The following first prints a=b c and then c:
1422 echo a=b c
1424 set -k
1425 echo a=b c
1426 This feature is intended for use with scripts written for early ver‐
1427 sions of the shell and its use in new scripts is strongly discouraged.
1428 It is likely to disappear someday.
1429 Functions.
1431 For historical reasons, there are two ways to define functions, the
1432 name() syntax and the function name syntax, described in the Commands
1433 section above. Shell functions are read in and stored internally.
1434 Alias names are resolved when the function is read. Functions are exe‐
1435 cuted like commands with the arguments passed as positional parameters.
1436 (See Execution below.)
1437 Functions defined by the function name syntax and called by name exe‐
1439 cute in the same process as the caller and share all files and present
1440 working directory with the caller. Traps caught by the caller are
1441 reset to their default action inside the function. A trap condition
1442 that is not caught or ignored by the function causes the function to
1443 terminate and the condition to be passed on to the caller. A trap on
1444 EXIT set inside a function is executed in the environment of the caller
1445 after the function completes. Ordinarily, variables are shared between
1446 the calling program and the function. However, the typeset special
1447 built-in command used within a function defines local variables whose
1448 scope includes the current function. They can be passed to functions
1449 that they call in the variable assignment list that precedes the call
1450 or as arguments passed as name references. Errors within functions
1451 return control to the caller.
1452 Functions defined with the name() syntax and functions defined with the
1454 function name syntax that are invoked with the . special built-in are
1455 executed in the caller's environment and share all variables and traps
1456 with the caller. Errors within these function executions cause the
1457 script that contains them to abort.
1458 The special built-in command return is used to return from function
1460 calls.
1461 Function names can be listed with the -f or +f option of the typeset
1463 special built-in command. The text of functions, when available, will
1464 also be listed with -f. Functions can be undefined with the -f option
1465 of the unset special built-in command.
1466 Ordinarily, functions are unset when the shell executes a shell script.
1468 Functions that need to be defined across separate invocations of the
1469 shell should be placed in a directory and the FPATH variable should
1470 contain the name of this directory. They may also be specified in the
1471 ENV file.
1472 Discipline Functions.
1474 Each variable can have zero or more discipline functions associated
1475 with it. The shell initially understands the discipline names get,
1476 set, append, and unset but can be added when defining new types. On
1477 most systems others can be added at run time via the C programming
1478 interface extension provided by the builtin built-in utility. If the
1479 get discipline is defined for a variable, it is invoked whenever the
1480 given variable is referenced. If the variable .sh.value is assigned a
1481 value inside the discipline function, the referenced variable will
1482 evaluate to this value instead. If the set discipline is defined for a
1483 variable, it is invoked whenever the given variable is assigned a
1484 value. If the append discipline is defined for a variable, it is
1485 invoked whenever a value is appended to the given variable. The vari‐
1486 able .sh.value is given the value of the variable before invoking the
1487 discipline, and the variable will be assigned the value of .sh.value
1488 after the discipline completes. If .sh.value is unset inside the dis‐
1489 cipline, then that value is unchanged. If the unset discipline is
1490 defined for a variable, it is invoked whenever the given variable is
1491 unset. The variable will not be unset unless it is unset explicitly
1492 from within this discipline function.
1493 The variable .sh.name contains the name of the variable for which the
1495 discipline function is called, .sh.subscript is the subscript of the
1496 variable, and .sh.value will contain the value being assigned inside
1497 the set discipline function. The variable _ is a reference to the
1498 variable including the subscript if any. For the set discipline,
1499 changing .sh.value will change the value that gets assigned. Finally,
1500 the expansion ${var.name}, when name is the name of a discipline, and
1501 there is no variable of this name, is equivalent to the command substi‐
1502 tution ${ var.name;}.
1503 Name Spaces.
1506 Commands and functions that are executed as part of the list of a
1507 namespace command that modify variables or create new ones, create a
1508 new variable whose name is the name of the name space as given by iden‐
1509 tifier preceded by .. When a variable whose name is name is refer‐
1510 enced, it is first searched for using .identifier.name. Similarly, a
1511 function defined by a command in the namespace list is created using
1512 the name space name preceded by a ..
1513 When the list of a namespace command contains a namespace command, the
1515 names of variable and functions that are created consist of the vari‐
1516 able or function name preceded by the list of identifiers each preceded
1517 by ..
1518 Outside of a name space, a variable or function created inside a names
1520 space can be referenced by preceding it with the name space name.
1521 By default, variables staring with .sh are in the sh name space.
1523 Type Variables.
1526 Typed variables provide a way to create data structure and objects. A
1527 type can be defined either by a shared library, by the enum built-in
1528 command described below, or by using the new -T option of the typeset
1529 built-in command. With the -T option of typeset, the type name, speci‐
1530 fied as an option argument to -T, is set with a compound variable
1531 assignment that defines the type. Function definitions can appear
1532 inside the compound variable assignment and these become discipline
1533 functions for this type and can be invoked or redefined by each
1534 instance of the type. The function name create is treated specially.
1535 It is invoked for each instance of the type that is created but is not
1536 inherited and cannot be redefined for each instance.
1537 When a type is defined a special built-in command of that name is
1539 added. These built-ins are declaration commands and follow the same
1540 expansion rules as all the special built-in commands defined below that
1541 are preceded by ††. These commands can subsequently be used inside
1542 further type definitions. The man page for these commands can be gen‐
1543 erated by using the --man option or any of the other -- options
1544 described with getopts. The -r, -a, -A, -h, and -S options of typeset
1545 are permitted with each of these new built-ins.
1546 An instance of a type is created by invoking the type name followed by
1548 one or more instance names. Each instance of the type is initialized
1549 with a copy of the sub-variables except for sub-variables that are
1550 defined with the -S option. Variables defined with the -S are shared
1551 by all instances of the type. Each instance can change the value of
1552 any sub-variable and can also define new discipline functions of the
1553 same names as those defined by the type definition as well as any stan‐
1554 dard discipline names. No additional sub-variables can be defined for
1555 any instance.
1556 When defining a type, if the value of a sub-variable is not set and the
1558 -r attribute is specified, it causes the sub-variable to be a required
1559 sub-variable. Whenever an instance of a type is created, all required
1560 sub-variables must be specified. These sub-variables become readonly
1561 in each instance.
1562 When unset is invoked on a sub-variable within a type, and the -r
1564 attribute has not been specified for this field, the value is reset to
1565 the default value associative with the type. Invoking unset on a type
1566 instance not contained within another type deletes all sub-variables
1567 and the variable itself.
1568 A type definition can be derived from another type definition by defin‐
1570 ing the first sub-variable name as _ and defining its type as the base
1571 type. Any remaining definitions will be additions and modifications
1572 that apply to the new type. If the new type name is the same is that
1573 of the base type, the type will be replaced and the original type will
1574 no longer be accessible.
1575 The typeset command with the -T and no option argument or operands will
1577 write all the type definitions to standard output in a form that that
1578 can be read in to create all they types.
1579 Jobs.
1581 If the monitor option of the set command is turned on, an interactive
1582 shell associates a job with each pipeline. It keeps a table of current
1583 jobs, printed by the jobs command, and assigns them small integer num‐
1584 bers. When a job is started asynchronously with &, the shell prints a
1585 line which looks like:
1586 [1] 1234
1588 indicating that the job which was started asynchronously was job number
1590 1 and had one (top-level) process, whose process id was 1234.
1591 This paragraph and the next require features that are not in all ver‐
1593 sions of UNIX and may not apply. If you are running a job and wish to
1594 do something else you may hit the key ^Z (control-Z) which sends a STOP
1595 signal to the current job. The shell will then normally indicate that
1596 the job has been `Stopped', and print another prompt. You can then
1597 manipulate the state of this job, putting it in the background with the
1598 bg command, or run some other commands and then eventually bring the
1599 job back into the foreground with the foreground command fg. A ^Z
1600 takes effect immediately and is like an interrupt in that pending out‐
1601 put and unread input are discarded when it is typed.
1602 A job being run in the background will stop if it tries to read from
1604 the terminal. Background jobs are normally allowed to produce output,
1605 but this can be disabled by giving the command stty tostop. If you set
1606 this tty option, then background jobs will stop when they try to pro‐
1607 duce output like they do when they try to read input.
1608 A job pool is a collection of jobs started with list & associated with
1610 a name.
1611 There are several ways to refer to jobs in the shell. A job can be
1613 referred to by the process id of any process of the job or by one of
1614 the following:
1615 %number
1616 The job with the given number.
1617 pool All the jobs in the job pool named by pool.
1618 pool.number
1619 The job number number in the job pool named by pool.
1620 %string
1621 Any job whose command line begins with string.
1622 %?string
1623 Any job whose command line contains string.
1624 %% Current job.
1625 %+ Equivalent to %%.
1626 %- Previous job. In addition, unless noted otherwise, wherever a
1627 job can be specified, the name of a background job pool can be
1628 used to represet all the jobs in that pool.
1629 The shell learns immediately whenever a process changes state. It nor‐
1631 mally informs you whenever a job becomes blocked so that no further
1632 progress is possible, but only just before it prints a prompt. This is
1633 done so that it does not otherwise disturb your work. The notify
1634 option of the set command causes the shell to print these job change
1635 messages as soon as they occur.
1636 When the monitor option is on, each background job that completes trig‐
1638 gers any trap set for CHLD.
1639 When you try to leave the shell while jobs are running or stopped, you
1641 will be warned that `You have stopped(running) jobs.' You may use the
1642 jobs command to see what they are. If you immediately try to exit
1643 again, the shell will not warn you a second time, and the stopped jobs
1644 will be terminated. When a login shell receives a HUP signal, it sends
1645 a HUP signal to each job that has not been disowned with the disown
1646 built-in command described below.
1647 Signals.
1649 The INT and QUIT signals for an invoked command are ignored if the com‐
1650 mand is followed by & and the monitor option is not active. Otherwise,
1651 signals have the values inherited by the shell from its parent (but see
1652 also the trap built-in command below).
1653 Execution.
1655 Each time a command is read, the above substitutions are carried out.
1656 If the command name matches one of the Special Built-in Commands listed
1657 below, it is executed within the current shell process. Next, the com‐
1658 mand name is checked to see if it matches a user defined function. If
1659 it does, the positional parameters are saved and then reset to the
1660 arguments of the function call. A function is also executed in the
1661 current shell process. When the function completes or issues a return,
1662 the positional parameter list is restored. For functions defined with
1663 the function name syntax, any trap set on EXIT within the function is
1664 executed. The exit value of a function is the value of the last com‐
1665 mand executed. If a command name is not a special built-in command or
1666 a user defined function, but it is one of the built-in commands listed
1667 below, it is executed in the current shell process.
1668 The shell variable PATH defines the search path for the directory con‐
1670 taining the command. Alternative directory names are separated by a
1671 colon (:). The default path is /bin:/usr/bin: (specifying /bin,
1672 /usr/bin, and the current directory in that order). The current direc‐
1673 tory can be specified by two or more adjacent colons, or by a colon at
1674 the beginning or end of the path list. If the command name contains a
1675 /, then the search path is not used. Otherwise, each directory in the
1676 path is searched for an executable file of the given name that is not a
1677 directory. If found, and if the shell determines that there is a
1678 built-in version of a command corresponding to a given pathname, this
1679 built-in is invoked in the current process. If found, and this direc‐
1680 tory is also contained in the value of the FPATH variable, then this
1681 file is loaded into the current shell environment as if it were the
1682 argument to the . command except that only preset aliases are expanded,
1683 and a function of the given name is executed as described above. If
1684 not found, and the file .paths is found, and this file contains a line
1685 of the form FPATH=path where path names an existing directory, and this
1686 directory contains a file of the given name, then this file is loaded
1687 into the current shell environment as if it were the argument to the .
1688 special built-in command and a function of the given name is executed.
1689 Otherwise, if found, a process is created and an attempt is made to
1690 execute the command via exec(2).
1691 When an executable is found, the directory where it is found in is
1693 searched for a file named .paths. If this file is found and it con‐
1694 tains a line of the form BUILTIN_LIB=value , then the library named by
1695 value will be searched for as if it were an option argument to builtin
1696 -f, and if it contains a built-in of the specified name this will be
1697 executed instead of a command by this name. Otherwise, if this file is
1698 found and it contains a line of the form name=value in the first or
1699 second line, then the environment variable name is modified by prepend‐
1700 ing the directory specified by value to the directory list. If value
1701 is not an absolute directory, then it specifies a directory relative to
1702 the directory that the executable was found. If the environment vari‐
1703 able name does not already exist it will be added to the environment
1704 list for the specified command.
1705 If the file has execute permission but is not an a.out file, it is
1707 assumed to be a file containing shell commands. A separate shell is
1708 spawned to read it. All non-exported variables are removed in this
1709 case. If the shell command file doesn't have read permission, or if
1710 the setuid and/or setgid bits are set on the file, then the shell exe‐
1711 cutes an agent whose job it is to set up the permissions and execute
1712 the shell with the shell command file passed down as an open file. A
1713 parenthesized command is executed in a sub-shell without removing non-
1714 exported variables.
1715 Command Re-entry.
1717 The text of the last HISTSIZE (default 512) commands entered from a
1718 terminal device is saved in a history file. The file $HOME/.sh_history
1719 is used if the HISTFILE variable is not set or if the file it names is
1720 not writable. A shell can access the commands of all interactive
1721 shells which use the same named HISTFILE. The built-in command hist is
1722 used to list or edit a portion of this file. The portion of the file
1723 to be edited or listed can be selected by number or by giving the first
1724 character or characters of the command. A single command or range of
1725 commands can be specified. If you do not specify an editor program as
1726 an argument to hist then the value of the variable HISTEDIT is used.
1727 If HISTEDIT is unset, the obsolete variable FCEDIT is used. If FCEDIT
1728 is not defined, then /bin/ed is used. The edited command(s) is printed
1729 and re-executed upon leaving the editor unless you quit without writ‐
1730 ing. The -s option (and in obsolete versions, the editor name -) is
1731 used to skip the editing phase and to re-execute the command. In this
1732 case a substitution parameter of the form old=new can be used to modify
1733 the command before execution. For example, with the preset alias r,
1734 which is aliased to ′hist -s′, typing `r bad=good c' will re-execute
1735 the most recent command which starts with the letter c, replacing the
1736 first occurrence of the string bad with the string good.
1737 In-line Editing Options.
1739 Normally, each command line entered from a terminal device is simply
1740 typed followed by a new-line (`RETURN' or `LINE FEED'). If either the
1741 emacs, gmacs, or vi option is active, the user can edit the command
1742 line. To be in either of these edit modes set the corresponding
1743 option. An editing option is automatically selected each time the VIS‐
1744 UAL or EDITOR variable is assigned a value ending in either of these
1745 option names.
1746 The editing features require that the user's terminal accept `RETURN'
1748 as carriage return without line feed and that a space (` ') must over‐
1749 write the current character on the screen.
1750 Unless the multiline option is on, the editing modes implement a con‐
1752 cept where the user is looking through a window at the current line.
1753 The window width is the value of COLUMNS if it is defined, otherwise
1754 80. If the window width is too small to display the prompt and leave
1755 at least 8 columns to enter input, the prompt is truncated from the
1756 left. If the line is longer than the window width minus two, a mark is
1757 displayed at the end of the window to notify the user. As the cursor
1758 moves and reaches the window boundaries the window will be centered
1759 about the cursor. The mark is a > (<, *) if the line extends on the
1760 right (left, both) side(s) of the window.
1761 The search commands in each edit mode provide access to the history
1763 file. Only strings are matched, not patterns, although a leading ^ in
1764 the string restricts the match to begin at the first character in the
1765 line.
1766 Each of the edit modes has an operation to list the files or commands
1768 that match a partially entered word. When applied to the first word on
1769 the line, or the first word after a ;, ⎪, &, or (, and the word does
1770 not begin with ∼ or contain a /, the list of aliases, functions, and
1771 executable commands defined by the PATH variable that could match the
1772 partial word is displayed. Otherwise, the list of files that match the
1773 given word is displayed. If the partially entered word does not con‐
1774 tain any file expansion characters, a * is appended before generating
1775 these lists. After displaying the generated list, the input line is
1776 redrawn. These operations are called command name listing and file
1777 name listing, respectively. There are additional operations, referred
1778 to as command name completion and file name completion, which compute
1779 the list of matching commands or files, but instead of printing the
1780 list, replace the current word with a complete or partial match. For
1781 file name completion, if the match is unique, a / is appended if the
1782 file is a directory and a space is appended if the file is not a direc‐
1783 tory. Otherwise, the longest common prefix for all the matching files
1784 replaces the word. For command name completion, only the portion of
1785 the file names after the last / are used to find the longest command
1786 prefix. If only a single name matches this prefix, then the word is
1787 replaced with the command name followed by a space. When using a tab
1788 for completion that does not yield a unique match, a subsequent tab
1789 will provide a numbered list of matching alternatives. A specific
1790 selection can be made by entering the selection number followed by a
1791 tab.
1792 Key Bindings.
1794 The KEYBD trap can be used to intercept keys as they are typed and
1795 change the characters that are actually seen by the shell. This trap
1796 is executed after each character (or sequence of characters when the
1797 first character is ESC) is entered while reading from a terminal. The
1798 variable .sh.edchar contains the character or character sequence which
1799 generated the trap. Changing the value of .sh.edchar in the trap
1800 action causes the shell to behave as if the new value were entered from
1801 the keyboard rather than the original value.
1802 The variable .sh.edcol is set to the input column number of the cursor
1804 at the time of the input. The variable .sh.edmode is set to ESC when
1805 in vi insert mode (see below) and is null otherwise. By prepending
1806 ${.sh.editmode} to a value assigned to .sh.edchar it will cause the
1807 shell to change to control mode if it is not already in this mode.
1808 This trap is not invoked for characters entered as arguments to editing
1810 directives, or while reading input for a character search.
1811 Emacs Editing Mode.
1813 This mode is entered by enabling either the emacs or gmacs option. The
1814 only difference between these two modes is the way they handle ^T. To
1815 edit, the user moves the cursor to the point needing correction and
1816 then inserts or deletes characters or words as needed. All the editing
1817 commands are control characters or escape sequences. The notation for
1818 control characters is caret (^) followed by the character. For exam‐
1819 ple, ^F is the notation for control F. This is entered by depressing
1820 `f' while holding down the `CTRL' (control) key. The `SHIFT' key is
1821 not depressed. (The notation ^? indicates the DEL (delete) key.)
1822 The notation for escape sequences is M- followed by a character. For
1824 example, M-f (pronounced Meta f) is entered by depressing ESC (ascii
1825 033) followed by `f'. (M-F would be the notation for ESC followed by
1826 `SHIFT' (capital) `F'.)
1827 All edit commands operate from any place on the line (not just at the
1829 beginning). Neither the `RETURN' nor the `LINE FEED' key is entered
1830 after edit commands except when noted.
1831 ^F Move cursor forward (right) one character.
1833 M-[C Move cursor forward (right) one character.
1834 M-f Move cursor forward one word. (The emacs editor's idea of a
1835 word is a string of characters consisting of only letters,
1836 digits and underscores.)
1837 ^B Move cursor backward (left) one character.
1838 M-[D Move cursor backward (left) one character.
1839 M-b Move cursor backward one word.
1840 ^A Move cursor to start of line.
1841 M-[H Move cursor to start of line.
1842 ^E Move cursor to end of line.
1843 M-[Y Move cursor to end of line.
1844 ^]char Move cursor forward to character char on current line.
1845 M-^]char Move cursor backward to character char on current line.
1846 ^X^X Interchange the cursor and mark.
1847 erase (User defined erase character as defined by the stty(1) com‐
1848 mand, usually ^H or #.) Delete previous character.
1849 lnext (User defined literal next character as defined by the
1850 stty(1) command, or ^V if not defined.) Removes the next
1851 character's editing features (if any).
1852 ^D Delete current character.
1853 M-d Delete current word.
1854 M-^H (Meta-backspace) Delete previous word.
1855 M-h Delete previous word.
1856 M-^? (Meta-DEL) Delete previous word (if your interrupt character
1857 is ^? (DEL, the default) then this command will not work).
1858 ^T Transpose current character with previous character and
1859 advance the cursor in emacs mode. Transpose two previous
1860 characters in gmacs mode.
1861 ^C Capitalize current character.
1862 M-c Capitalize current word.
1863 M-l Change the current word to lower case.
1864 ^K Delete from the cursor to the end of the line. If preceded
1865 by a numerical parameter whose value is less than the current
1866 cursor position, then delete from given position up to the
1867 cursor. If preceded by a numerical parameter whose value is
1868 greater than the current cursor position, then delete from
1869 cursor up to given cursor position.
1870 ^W Kill from the cursor to the mark.
1871 M-p Push the region from the cursor to the mark on the stack.
1872 kill (User defined kill character as defined by the stty command,
1873 usually ^G or @.) Kill the entire current line. If two kill
1874 characters are entered in succession, all kill characters
1875 from then on cause a line feed (useful when using paper ter‐
1876 minals).
1877 ^Y Restore last item removed from line. (Yank item back to the
1878 line.)
1879 ^L Line feed and print current line.
1880 M-^L Clear the screen.
1881 ^@ (Null character) Set mark.
1882 M-space (Meta space) Set mark.
1883 ^J (New line) Execute the current line.
1884 ^M (Return) Execute the current line.
1885 eof End-of-file character, normally ^D, is processed as an End-
1886 of-file only if the current line is null.
1887 ^P Fetch previous command. Each time ^P is entered the previous
1888 command back in time is accessed. Moves back one line when
1889 not on the first line of a multi-line command.
1890 M-[A If the cursor is at the end of the line, it is equivalent to
1891 ^R with string set to the contents of the current line. Oth‐
1892 erwise, it is equivalent to ^P.
1893 M-< Fetch the least recent (oldest) history line.
1894 M-> Fetch the most recent (youngest) history line.
1895 ^N Fetch next command line. Each time ^N is entered the next
1896 command line forward in time is accessed.
1897 M-[B Equivalent to ^N.
1898 ^Rstring Reverse search history for a previous command line containing
1899 string. If a parameter of zero is given, the search is for‐
1900 ward. String is terminated by a `RETURN' or `NEW LINE'. If
1901 string is preceded by a ^, the matched line must begin with
1902 string. If string is omitted, then the next command line
1903 containing the most recent string is accessed. In this case
1904 a parameter of zero reverses the direction of the search.
1905 ^O Operate - Execute the current line and fetch the next line
1906 relative to current line from the history file.
1907 M-digits (Escape) Define numeric parameter, the digits are taken as a
1908 parameter to the next command. The commands that accept a
1909 parameter are ^F, ^B, erase, ^C, ^D, ^K, ^R, ^P, ^N, ^], M-.,
1910 M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l and M-^H.
1911 M-letter Soft-key - Your alias list is searched for an alias by the
1912 name _letter and if an alias of this name is defined, its
1913 value will be inserted on the input queue. The letter must
1914 not be one of the above meta-functions.
1915 M-[letter Soft-key - Your alias list is searched for an alias by the
1916 name __letter and if an alias of this name is defined, its
1917 value will be inserted on the input queue. This can be used
1918 to program function keys on many terminals.
1919 M-. The last word of the previous command is inserted on the
1920 line. If preceded by a numeric parameter, the value of this
1921 parameter determines which word to insert rather than the
1922 last word.
1923 M-_ Same as M-..
1924 M-* Attempt file name generation on the current word. An aster‐
1925 isk is appended if the word doesn't match any file or contain
1926 any special pattern characters.
1927 M-ESC Command or file name completion as described above.
1928 ^I tab Attempts command or file name completion as described above.
1929 If a partial completion occurs, repeating this will behave as
1930 if M-= were entered. If no match is found or entered after
1931 space, a tab is inserted.
1932 M-= If not preceded by a numeric parameter, it generates the list
1933 of matching commands or file names as described above. Oth‐
1934 erwise, the word under the cursor is replaced by the item
1935 corresponding to the value of the numeric parameter from the
1936 most recently generated command or file list. If the cursor
1937 is not on a word, it is inserted instead.
1938 ^U Multiply parameter of next command by 4.
1939 \ Escape next character. Editing characters, the user's erase,
1940 kill and interrupt (normally ^?) characters may be entered
1941 in a command line or in a search string if preceded by a \.
1942 The \ removes the next character's editing features (if any).
1943 M-^V Display version of the shell.
1944 M-# If the line does not begin with a #, a # is inserted at the
1945 beginning of the line and after each new-line, and the line
1946 is entered. This causes a comment to be inserted in the his‐
1947 tory file. If the line begins with a #, the # is deleted and
1948 one # after each new-line is also deleted.
1949 Vi Editing Mode.
1951 There are two typing modes. Initially, when you enter a command you
1952 are in the input mode. To edit, the user enters control mode by typing
1953 ESC (033) and moves the cursor to the point needing correction and then
1954 inserts or deletes characters or words as needed. Most control com‐
1955 mands accept an optional repeat count prior to the command.
1956 When in vi mode on most systems, canonical processing is initially
1958 enabled and the command will be echoed again if the speed is 1200 baud
1959 or greater and it contains any control characters or less than one sec‐
1960 ond has elapsed since the prompt was printed. The ESC character termi‐
1961 nates canonical processing for the remainder of the command and the
1962 user can then modify the command line. This scheme has the advantages
1963 of canonical processing with the type-ahead echoing of raw mode.
1964 If the option viraw is also set, the terminal will always have canoni‐
1966 cal processing disabled. This mode is implicit for systems that do not
1967 support two alternate end of line delimiters, and may be helpful for
1968 certain terminals.
1969 Input Edit Commands
1971 By default the editor is in input mode.
1972 erase (User defined erase character as defined by the stty
1973 command, usually ^H or #.) Delete previous character.
1974 ^W Delete the previous blank separated word. On some
1975 systems the viraw option may be required for this to
1976 work.
1977 eof As the first character of the line causes the shell to
1978 terminate unless the ignoreeof option is set. Other‐
1979 wise this character is ignored.
1980 lnext (User defined literal next character as defined by the
1981 stty(1) or ^V if not defined.) Removes the next char‐
1982 acter's editing features (if any). On some systems
1983 the viraw option may be required for this to work.
1984 \ Escape the next erase or kill character.
1985 ^I tab Attempts command or file name completion as described
1986 above and returns to input mode. If a partial comple‐
1987 tion occurs, repeating this will behave as if = were
1988 entered from control mode. If no match is found or
1989 entered after space, a tab is inserted.
1990 Motion Edit Commands
1991 These commands will move the cursor.
1992 [count]l Cursor forward (right) one character.
1993 [count][C Cursor forward (right) one character.
1994 [count]w Cursor forward one alpha-numeric word.
1995 [count]W Cursor to the beginning of the next word that follows
1996 a blank.
1997 [count]e Cursor to end of word.
1998 [count]E Cursor to end of the current blank delimited word.
1999 [count]h Cursor backward (left) one character.
2000 [count][D Cursor backward (left) one character.
2001 [count]b Cursor backward one word.
2002 [count]B Cursor to preceding blank separated word.
2003 [count]⎪ Cursor to column count.
2004 [count]fc Find the next character c in the current line.
2005 [count]Fc Find the previous character c in the current line.
2006 [count]tc Equivalent to f followed by h.
2007 [count]Tc Equivalent to F followed by l.
2008 [count]; Repeats count times, the last single character find
2009 command, f, F, t, or T.
2010 [count], Reverses the last single character find command count
2011 times.
2012 0 Cursor to start of line.
2013 ^ Cursor to start of line.
2014 [H Cursor to first non-blank character in line.
2015 $ Cursor to end of line.
2016 [Y Cursor to end of line.
2017 % Moves to balancing (, ), {, }, [, or ]. If cursor is
2018 not on one of the above characters, the remainder of
2019 the line is searched for the first occurrence of one
2020 of the above characters first.
2021 Search Edit Commands
2022 These commands access your command history.
2023 [count]k Fetch previous command. Each time k is entered the
2024 previous command back in time is accessed.
2025 [count]- Equivalent to k.
2026 [count][A If cursor is at the end of the line it is equivalent
2027 to / with string^set to the contents of the current
2028 line. Otherwise, it is equivalent to k.
2029 [count]j Fetch next command. Each time j is entered the next
2030 command forward in time is accessed.
2031 [count]+ Equivalent to j.
2032 [count][B Equivalent to j.
2033 [count]G The command number count is fetched. The default is
2034 the least recent history command.
2035 /string Search backward through history for a previous command
2036 containing string. String is terminated by a `RETURN'
2037 or `NEW LINE'. If string is preceded by a ^, the
2038 matched line must begin with string. If string is
2039 null, the previous string will be used.
2040 ?string Same as / except that search will be in the forward
2041 direction.
2042 n Search for next match of the last pattern to / or ?
2043 commands.
2044 N Search for next match of the last pattern to / or ?,
2045 but in reverse direction.
2046 Text Modification Edit Commands
2047 These commands will modify the line.
2048 a Enter input mode and enter text after the current
2049 character.
2050 A Append text to the end of the line. Equivalent to $a.
2051 [count]cmotion
2052 c[count]motion
2053 Delete current character through the character that
2054 motion would move the cursor to and enter input mode.
2055 If motion is c, the entire line will be deleted and
2056 input mode entered.
2057 C Delete the current character through the end of line
2058 and enter input mode. Equivalent to c$.
2059 S Equivalent to cc.
2060 [count]s Replace characters under the cursor in input mode.
2061 D Delete the current character through the end of line.
2062 Equivalent to d$.
2063 [count]dmotion
2064 d[count]motion
2065 Delete current character through the character that
2066 motion would move to. If motion is d , the entire
2067 line will be deleted.
2068 i Enter input mode and insert text before the current
2069 character.
2070 I Insert text before the beginning of the line. Equiva‐
2071 lent to 0i.
2072 [count]P Place the previous text modification before the cur‐
2073 sor.
2074 [count]p Place the previous text modification after the cursor.
2075 R Enter input mode and replace characters on the screen
2076 with characters you type overlay fashion.
2077 [count]rc Replace the count character(s) starting at the current
2078 cursor position with c, and advance the cursor.
2079 [count]x Delete current character.
2080 [count]X Delete preceding character.
2081 [count]. Repeat the previous text modification command.
2082 [count]∼ Invert the case of the count character(s) starting at
2083 the current cursor position and advance the cursor.
2084 [count]_ Causes the count word of the previous command to be
2085 appended and input mode entered. The last word is
2086 used if count is omitted.
2087 * Causes an * to be appended to the current word and
2088 file name generation attempted. If no match is found,
2089 it rings the bell. Otherwise, the word is replaced by
2090 the matching pattern and input mode is entered.
2091 \ Command or file name completion as described above.
2092 Other Edit Commands
2093 Miscellaneous commands.
2094 [count]ymotion
2095 y[count]motion
2096 Yank current character through character that motion
2097 would move the cursor to and puts them into the delete
2098 buffer. The text and cursor are unchanged.
2099 yy Yanks the entire line.
2100 Y Yanks from current position to end of line. Equiva‐
2101 lent to y$.
2102 u Undo the last text modifying command.
2103 U Undo all the text modifying commands performed on the
2104 line.
2105 [count]v Returns the command hist -e ${VISUAL:-${EDITOR:-vi}}
2106 count in the input buffer. If count is omitted, then
2107 the current line is used.
2108 ^L Line feed and print current line. Has effect only in
2109 control mode.
2110 ^J (New line) Execute the current line, regardless of
2111 mode.
2112 ^M (Return) Execute the current line, regardless of mode.
2113 # If the first character of the command is a #, then
2114 this command deletes this # and each # that follows a
2115 newline. Otherwise, sends the line after inserting a
2116 # in front of each line in the command. Useful for
2117 causing the current line to be inserted in the history
2118 as a comment and uncommenting previously commented
2119 commands in the history file.
2120 [count]= If count is not specified, it generates the list of
2121 matching commands or file names as described above.
2122 Otherwise, the word under the the cursor is replaced
2123 by the count item from the most recently generated
2124 command or file list. If the cursor is not on a word,
2125 it is inserted instead.
2126 @letter Your alias list is searched for an alias by the name
2127 _letter and if an alias of this name is defined, its
2128 value will be inserted on the input queue for process‐
2129 ing.
2130 ^V Display version of the shell.
2131 Built-in Commands.
2133 The following simple-commands are executed in the shell process.
2134 Input/Output redirection is permitted. Unless otherwise indicated, the
2135 output is written on file descriptor 1 and the exit status, when there
2136 is no syntax error, is zero. Except for :, true, false, echo, newgrp,
2137 and login, all built-in commands accept -- to indicate end of options.
2138 They also interpret the option --man as a request to display the man
2139 page onto standard error and -? as a help request which prints a usage
2140 message on standard error. Commands that are preceded by one or two †
2141 symbols are special built-in commands and are treated specially in the
2142 following ways:
2143 1. Variable assignment lists preceding the command remain in effect
2144 when the command completes.
2145 2. I/O redirections are processed after variable assignments.
2146 3. Errors cause a script that contains them to abort.
2147 4. They are not valid function names.
2148 5. Words following a command preceded by †† that are in the format
2149 of a variable assignment are expanded with the same rules as a
2150 variable assignment. This means that tilde substitution is per‐
2151 formed after the = sign and field splitting and file name gener‐
2152 ation are not performed. These are called declaration built-
2153 ins.
2154 † : [ arg ... ]
2156 The command only expands parameters.
2157 † . name [ arg ... ]
2159 If name is a function defined with the function name reserved
2160 word syntax, the function is executed in the current environment
2161 (as if it had been defined with the name() syntax.) Otherwise
2162 if name refers to a file, the file is read in its entirety and
2163 the commands are executed in the current shell environment. The
2164 search path specified by PATH is used to find the directory con‐
2165 taining the file. If any arguments arg are given, they become
2166 the positional parameters while processing the . command and
2167 the original positional parameters are restored upon completion.
2168 Otherwise the positional parameters are unchanged. The exit
2169 status is the exit status of the last command executed.
2170 †† alias [ -ptx ] [ name[ =value ] ] ...
2172 alias with no arguments prints the list of aliases in the form
2173 name=value on standard output. The -p option causes the word
2174 alias to be inserted before each one. When one or more argu‐
2175 ments are given, an alias is defined for each name whose value
2176 is given. A trailing space in value causes the next word to be
2177 checked for alias substitution. The obsolete -t option is used
2178 to set and list tracked aliases. The value of a tracked alias
2179 is the full pathname corresponding to the given name. The value
2180 becomes undefined when the value of PATH is reset but the alias
2181 remains tracked. Without the -t option, for each name in the
2182 argument list for which no value is given, the name and value of
2183 the alias is printed. The obsolete -x option has no effect.
2184 The exit status is non-zero if a name is given, but no value,
2185 and no alias has been defined for the name.
2186 bg [ job... ]
2188 This command is only on systems that support job control. Puts
2189 each specified job into the background. The current job is put
2190 in the background if job is not specified. See Jobs for a
2191 description of the format of job.
2192 † break [ n ]
2194 Exit from the enclosing for, while, until, or select loop, if
2195 any. If n is specified, then break n levels.
2196 builtin [ -ds ] [ -f file ] [ name ... ]
2198 If name is not specified, and no -f option is specified, the
2199 built-ins are printed on standard output. The -s option prints
2200 only the special built-ins. Otherwise, each name represents the
2201 pathname whose basename is the name of the built-in. The entry
2202 point function name is determined by prepending b_ to the built-
2203 in name. The ISO C/C++ prototype is b_mycommand(int argc, char
2204 *argv[], void *context) for the builtin command mycommand where
2205 argv is array an of argc elements and context is an optional
2206 pointer to a Shell_t structure as described in <ast/shell.h>.
2207 Special built-ins cannot be bound to a pathname or deleted. The
2208 -d option deletes each of the given built-ins. On systems that
2209 support dynamic loading, the -f option names a shared library
2210 containing the code for built-ins. The shared library prefix
2211 and/or suffix, which depend on the system, can be omitted. Once
2212 a library is loaded, its symbols become available for subsequent
2213 invocations of builtin. Multiple libraries can be specified
2214 with separate invocations of the builtin command. Libraries are
2215 searched in the reverse order in which they are specified. When
2216 a library is loaded, it looks for a function in the library
2217 whose name is lib_init() and invokes this function with an argu‐
2218 ment of 0.
2219 cd [ -LP ] [ arg ]
2221 cd [ -LP ] old new
2222 This command can be in either of two forms. In the first form
2223 it changes the current directory to arg. If arg is - the direc‐
2224 tory is changed to the previous directory. The shell variable
2225 HOME is the default arg. The variable PWD is set to the current
2226 directory. The shell variable CDPATH defines the search path
2227 for the directory containing arg. Alternative directory names
2228 are separated by a colon (:). The default path is <null> (spec‐
2229 ifying the current directory). Note that the current directory
2230 is specified by a null path name, which can appear immediately
2231 after the equal sign or between the colon delimiters anywhere
2232 else in the path list. If arg begins with a / then the search
2233 path is not used. Otherwise, each directory in the path is
2234 searched for arg.
2235 The second form of cd substitutes the string new for the string
2236 old in the current directory name, PWD, and tries to change to
2237 this new directory.
2238 By default, symbolic link names are treated literally when find‐
2239 ing the directory name. This is equivalent to the -L option.
2240 The -P option causes symbolic links to be resolved when deter‐
2241 mining the directory. The last instance of -L or -P on the com‐
2242 mand line determines which method is used.
2243 The cd command may not be executed by rksh. rksh93.
2244 command [ -pvxV ] name [ arg ... ]
2246 Without the -v or -V options, command executes name with the
2247 arguments given by arg. The -p option causes a default path to
2248 be searched rather than the one defined by the value of PATH.
2249 Functions will not be searched for when finding name. In addi‐
2250 tion, if name refers to a special built-in, none of the special
2251 properties associated with the leading daggers will be honored.
2252 (For example, the predefined alias redirect=′command exec′ pre‐
2253 vents a script from terminating when an invalid redirection is
2254 given.) With the -x option, if command execution would result
2255 in a failure because there are too many arguments, errno E2BIG,
2256 the shell will invoke command name multiple times with a subset
2257 of the arguments on each invocation. Arguments that occur prior
2258 to the first word that expands to multiple arguments and after
2259 the last word that expands to multiple arguments will be passed
2260 on each invocation. The exit status will be the maximum invoca‐
2261 tion exit status. With the -v option, command is equivalent to
2262 the built-in whence command described below. The -V option
2263 causes command to act like whence -v.
2264 † continue [ n ]
2266 Resume the next iteration of the enclosing for, while, until, or
2267 select loop. If n is specified, then resume at the n-th enclos‐
2268 ing loop.
2269 disown [ job... ]
2271 Causes the shell not to send a HUP signal to each given job, or
2272 all active jobs if job is omitted, when a login shell termi‐
2273 nates.
2274 echo [ arg ... ]
2276 When the first arg does not begin with a -, and none of the
2277 arguments contain a \, then echo prints each of its arguments
2278 separated by a space and terminated by a new-line. Otherwise,
2279 the behavior of echo is system dependent and print or printf
2280 described below should be used. See echo(1) for usage and
2281 description.
2282 †† enum [ -i ] type[=(value ...) ]
2284 Creates a declaration command named type that is an integer type
2285 that allows one of the specified values as enumeration names.
2286 If =(value ...) is omitted, then type must be an indexed array
2287 variable with at least two elements and the values are taken
2288 from this array variable. If -i is specified the values are
2289 case insensitive.
2290 † eval [ arg ... ]
2292 The arguments are read as input to the shell and the resulting
2293 command(s) executed.
2294 † exec [ -c ] [ -a name ] [ arg ... ]
2296 If arg is given, the command specified by the arguments is exe‐
2297 cuted in place of this shell without creating a new process.
2298 The -c option causes the environment to be cleared before apply‐
2299 ing variable assignments associated with the exec invocation.
2300 The -a option causes name rather than the first arg, to become
2301 argv[0] for the new process. Input/output arguments may appear
2302 and affect the current process. If arg is not given, the effect
2303 of this command is to modify file descriptors as prescribed by
2304 the input/output redirection list. In this case, any file
2305 descriptor numbers greater than 2 that are opened with this
2306 mechanism are closed when invoking another program.
2307 † exit [ n ]
2309 Causes the shell to exit with the exit status specified by n.
2310 The value will be the least significant 8 bits of the specified
2311 status. If n is omitted, then the exit status is that of the
2312 last command executed. An end-of-file will also cause the shell
2313 to exit except for a shell which has the ignoreeof option (see
2314 set below) turned on.
2315 †† export [ -p ] [ name[=value] ] ...
2317 If name is not given, the names and values of each variable with
2318 the export attribute are printed with the values quoted in a
2319 manner that allows them to be re-input. The export command is
2320 the same as typeset -x except that if you use export within a
2321 function, no local variable is created. The -p option causes
2322 the word export to be inserted before each one. Otherwise, the
2323 given names are marked for automatic export to the environment
2324 of subsequently-executed commands.
2325 false Does nothing, and exits 1. Used with until for infinite loops.
2327 fg [ job... ]
2329 This command is only on systems that support job control. Each
2330 job specified is brought to the foreground and waited for in the
2331 specified order. Otherwise, the current job is brought into the
2332 foreground. See Jobs for a description of the format of job.
2333 getconf [ name [ pathname ] ]
2335 Prints the current value of the configuration parameter given by
2336 name. The configuration parameters are defined by the IEEE
2337 POSIX 1003.1 and IEEE POSIX 1003.2 standards. (See pathconf(2)
2338 and sysconf(2).) The pathname argument is required for parame‐
2339 ters whose value depends on the location in the file system. If
2340 no arguments are given, getconf prints the names and values of
2341 the current configuration parameters. The pathname / is used
2342 for each of the parameters that requires pathname.
2343 getopts [ -a name ] optstring vname [ arg ... ]
2345 Checks arg for legal options. If arg is omitted, the positional
2346 parameters are used. An option argument begins with a + or a -.
2347 An option not beginning with + or - or the argument -- ends the
2348 options. Options beginning with + are only recognized when opt‐
2349 string begins with a +. optstring contains the letters that
2350 getopts recognizes. If a letter is followed by a :, that option
2351 is expected to have an argument. The options can be separated
2352 from the argument by blanks. The option -? causes getopts to
2353 generate a usage message on standard error. The -a argument can
2354 be used to specify the name to use for the usage message, which
2355 defaults to $0.
2356 getopts places the next option letter it finds inside variable
2357 vname each time it is invoked. The option letter will be
2358 prepended with a + when arg begins with a +. The index of the
2359 next arg is stored in OPTIND. The option argument, if any, gets
2360 stored in OPTARG.
2361 A leading : in optstring causes getopts to store the letter of
2362 an invalid option in OPTARG, and to set vname to ? for an
2363 unknown option and to : when a required option argument is miss‐
2364 ing. Otherwise, getopts prints an error message. The exit sta‐
2365 tus is non-zero when there are no more options.
2366 There is no way to specify any of the options :, +, -, ?, [, and
2367 ]. The option # can only be specified as the first option.
2368 hist [ -e ename ] [ -nlr ] [ first [ last ] ]
2370 hist -s [ old=new ] [ command ]
2371 In the first form, a range of commands from first to last is
2372 selected from the last HISTSIZE commands that were typed at the
2373 terminal. The arguments first and last may be specified as a
2374 number or as a string. A string is used to locate the most
2375 recent command starting with the given string. A negative num‐
2376 ber is used as an offset to the current command number. If the
2377 -l option is selected, the commands are listed on standard out‐
2378 put. Otherwise, the editor program ename is invoked on a file
2379 containing these keyboard commands. If ename is not supplied,
2380 then the value of the variable HISTEDIT is used. If HISTEDIT is
2381 not set, then FCEDIT (default /bin/ed) is used as the editor.
2382 When editing is complete, the edited command(s) is executed if
2383 the changes have been saved. If last is not specified, then it
2384 will be set to first. If first is not specified, the default is
2385 the previous command for editing and -16 for listing. The
2386 option -r reverses the order of the commands and the option -n
2387 suppresses command numbers when listing. In the second form,
2388 command is interpreted as first described above and defaults to
2389 the last command executed. The resulting command is executed
2390 after the optional substitution old=new is performed.
2391 jobs [ -lnp ] [ job ... ]
2393 Lists information about each given job; or all active jobs if
2394 job is omitted. The -l option lists process ids in addition to
2395 the normal information. The -n option only displays jobs that
2396 have stopped or exited since last notified. The -p option
2397 causes only the process group to be listed. See Jobs for a
2398 description of the format of job.
2399 kill [ -s signame ] job ...
2401 kill [ -n signum ] job ...
2402 kill -l [ sig ... ]
2403 Sends either the TERM (terminate) signal or the specified signal
2404 to the specified jobs or processes. Signals are either given by
2405 number with the -n option or by name with the -s option (as
2406 given in <signal.h>, stripped of the prefix ``SIG'' with the
2407 exception that SIGCLD is named CHLD). For backward compatibil‐
2408 ity, the n and s can be omitted and the number or name placed
2409 immediately after the -. If the signal being sent is TERM (ter‐
2410 minate) or HUP (hangup), then the job or process will be sent a
2411 CONT (continue) signal if it is stopped. The argument job can
2412 be the process id of a process that is not a member of one of
2413 the active jobs. See Jobs for a description of the format of
2414 job. In the third form, kill -l, if sig is not specified, the
2415 signal names are listed. Otherwise, for each sig that is a
2416 name, the corresponding signal number is listed. For each sig
2417 that is a number, the signal name corresponding to the least
2418 significant 8 bits of sig is listed.
2419 let arg ...
2421 Each arg is a separate arithmetic expression to be evaluated.
2422 See Arithmetic Evaluation above, for a description of arithmetic
2423 expression evaluation.
2424 The exit status is 0 if the value of the last expression is non-
2425 zero, and 1 otherwise.
2426 † newgrp [ arg ... ]
2428 Equivalent to exec /bin/newgrp arg ....
2429 print [ -CRenprsv ] [ -u unit] [ -f format ] [ arg ... ]
2431 With no options or with option - or --, each arg is printed on
2432 standard output. The -f option causes the arguments to be
2433 printed as described by printf. In this case, any e, n, r, R
2434 options are ignored. Otherwise, unless the -C, -R, -r, or -v
2435 are specified, the following escape conventions will be applied:
2436 \a The alert character (ascii 07).
2437 \b The backspace character (ascii 010).
2438 \c Causes print to end without processing more arguments and
2439 not adding a new-line.
2440 \f The formfeed character (ascii 014).
2441 \n The new-line character (ascii 012).
2442 \r The carriage return character (ascii 015).
2443 \t The tab character (ascii 011).
2444 \v The vertical tab character (ascii 013).
2445 \E The escape character (ascii 033).
2446 \\ The backslash character \.
2447 \0x The character defined by the 1, 2, or 3-digit octal
2448 string given by x.
2449 The -R option will print all subsequent arguments and options
2451 other than -n. The -e causes the above escape conventions to be
2452 applied. This is the default behavior. It reverses the effect
2453 of an earlier -r. The -p option causes the arguments to be
2454 written onto the pipe of the process spawned with ⎪& instead of
2455 standard output. The -v option treats each arg as a variable
2456 name and writes the value in the printf %B format. The -C
2457 option treats each arg as a variable name and writes the value
2458 in the printf %#B format. The -s option causes the arguments to
2459 be written onto the history file instead of standard output.
2460 The -u option can be used to specify a one digit file descriptor
2461 unit number unit on which the output will be placed. The
2462 default is 1. If the option -n is used, no new-line is added to
2463 the output.
2464 printf format [ arg ... ]
2466 The arguments arg are printed on standard output in accordance
2467 with the ANSI-C formatting rules associated with the format
2468 string format. If the number of arguments exceeds the number of
2469 format specifications, the format string is reused to format
2470 remaining arguments. The following extensions can also be used:
2471 %b A %b format can be used instead of %s to cause escape
2472 sequences in the corresponding arg to be expanded as
2473 described in print.
2474 %B A %B option causes each of the arguments to be treated as
2475 variable names and the binary value of variable will be
2476 printed. The alternate flag # causes a compound variable
2477 to be output on a single line. This is most useful for
2478 compound variables and variables whose attribute is -b.
2479 %H A %H format can be used instead of %s to cause characters
2480 in arg that are special in HTML and XML to be output as
2481 their entity name.
2482 %P A %P format can be used instead of %s to cause arg to be
2483 interpreted as an extended regular expression and be
2484 printed as a shell pattern.
2485 The format modifier
2486 L can be used with the %c and %s formats to treat preci‐
2487 sion as character width instead of byte count.
2488 The format modifier
2489 , can be used with the %d and %f formats to treat sepa‐
2490 rate groups of digits with the grouping delimiter which
2491 is %d in the C locale.
2492 %R A %R format can be used instead of %s to cause arg to be
2493 interpreted as a shell pattern and to be printed as an
2494 extended regular expression.
2495 %q A %q format can be used instead of %s to cause the
2496 resulting string to be quoted in a manner than can be
2497 reinput to the shell.
2498 %(date-format)T
2499 A %(date-format)T format can be use to treat an argument
2500 as a date/time string and to format the date/time accord‐
2501 ing to the date-format as defined for the date(1) com‐
2502 mand.
2503 %Z A %Z format will output a byte whose value is 0.
2504 %d The precision field of the %d format can be followed by a
2505 . and the output base. In this case, the # flag charac‐
2506 ter causes base# to be prepended.
2507 # The # flag when used with the d specifier without an out‐
2508 put base, causes the output to be displayed in thousands
2509 units with one of the suffixes k M G T P E to indicate
2510 the unit. The # flag when used with the i specifier
2511 causes the output to be displayed in 1024 with one of the
2512 suffixes Ki Mi Gi Ti Pi Ei to indicate the unit.
2513 = The = flag has been added to center the output within the
2514 specified field width.
2515 pwd [ -LP ]
2517 Outputs the value of the current working directory. The -L
2518 option is the default; it prints the logical name of the current
2519 directory. If the -P option is given, all symbolic links are
2520 resolved from the name. The last instance of -L or -P on the
2521 command line determines which method is used.
2522 read [ -ACprsv ] [ -d delim] [ -n n] [ [ -N n] [ [ -t timeout] [ -u
2524 unit] [ vname?prompt ] [ vname ... ]
2525 The shell input mechanism. One line is read and is broken up
2526 into fields using the characters in IFS as separators. The
2527 escape character, \, is used to remove any special meaning for
2528 the next character and for line continuation. The -d option
2529 causes the read to continue to the first character of delim
2530 rather than new-line. The -n option causes at most n bytes to
2531 read rather a full line but will return when reading from a slow
2532 device as soon as any characters have been read. The -N option
2533 causes exactly n to be read unless an end-of-file has been
2534 encountered or the read times out because of the -t option. In
2535 raw mode, -r, the \ character is not treated specially. The
2536 first field is assigned to the first vname, the second field to
2537 the second vname, etc., with leftover fields assigned to the
2538 last vname. When vname has the binary attribute and -n or -N is
2539 specified, the bytes that are read are stored directly into the
2540 variable. If the -v is specified, then the value of the first
2541 vname will be used as a default value when reading from a termi‐
2542 nal device. The -A option causes the variable vname to be unset
2543 and each field that is read to be stored in successive elements
2544 of the indexed array vname. The -C option causes the variable
2545 vname to be read as a compound variable. Blanks will be ignored
2546 when finding the beginning open parenthesis. The -p option
2547 causes the input line to be taken from the input pipe of a
2548 process spawned by the shell using ⎪&. If the -s option is
2549 present, the input will be saved as a command in the history
2550 file. The option -u can be used to specify a one digit file
2551 descriptor unit unit to read from. The file descriptor can be
2552 opened with the exec special built-in command. The default
2553 value of unit n is 0. The option -t is used to specify a time‐
2554 out in seconds when reading from a terminal or pipe. If vname
2555 is omitted, then REPLY is used as the default vname. An end-of-
2556 file with the -p option causes cleanup for this process so that
2557 another can be spawned. If the first argument contains a ?, the
2558 remainder of this word is used as a prompt on standard error
2559 when the shell is interactive. The exit status is 0 unless an
2560 end-of-file is encountered or read has timed out.
2561 †† readonly [ -p ] [ vname[=value] ] ...
2563 If vname is not given, the names and values of each variable
2564 with the readonly attribute is printed with the values quoted in
2565 a manner that allows them to be re-inputted. The -p option
2566 causes the word readonly to be inserted before each one. Other‐
2567 wise, the given vnames are marked readonly and these names can‐
2568 not be changed by subsequent assignment. When defining a type,
2569 if the value of a readonly sub-variable is not defined the value
2570 is required when creating each instance.
2571 † return [ n ]
2573 Causes a shell function or . script to return to the invoking
2574 script with the exit status specified by n. The value will be
2575 the least significant 8 bits of the specified status. If n is
2576 omitted, then the return status is that of the last command exe‐
2577 cuted. If return is invoked while not in a function or a .
2578 script, then it behaves the same as exit.
2579 † set [ ±BCGabefhkmnoprstuvx ] [ ±o [ option ] ] ... [ ±A vname ] [
2581 arg ... ]
2582 The options for this command have meaning as follows:
2583 -A Array assignment. Unset the variable vname and assign
2584 values sequentially from the arg list. If +A is used,
2585 the variable vname is not unset first.
2586 -B Enable brace pattern field generation. This is the
2587 default behavior.
2588 -B Enable brace group expansion. On by default.
2589 -C Prevents redirection > from truncating existing files.
2590 Files that are created are opened with the O_EXCL mode.
2591 Requires >⎪ to truncate a file when turned on.
2592 -G Causes the pattern ∗∗ by itself to match files and zero
2593 or more directories and sub-directories when used for
2594 file name generation. If followed by a / only directo‐
2595 ries and sub-directories are matched.
2596 -a All subsequent variables that are defined are automati‐
2597 cally exported.
2598 -b Prints job completion messages as soon as a background
2599 job changes state rather than waiting for the next
2600 prompt.
2601 -e Unless contained in a ⎪⎪ or && command, or the command
2602 following an if while or until command or in the pipe‐
2603 line following !, if a command has a non-zero exit sta‐
2604 tus, execute the ERR trap, if set, and exit. This mode
2605 is disabled while reading profiles.
2606 -f Disables file name generation.
2607 -h Each command becomes a tracked alias when first encoun‐
2608 tered.
2609 -k (Obsolete). All variable assignment arguments are placed
2610 in the environment for a command, not just those that
2611 precede the command name.
2612 -m Background jobs will run in a separate process group and
2613 a line will print upon completion. The exit status of
2614 background jobs is reported in a completion message. On
2615 systems with job control, this option is turned on auto‐
2616 matically for interactive shells.
2617 -n Read commands and check them for syntax errors, but do
2618 not execute them. Ignored for interactive shells.
2619 -o The following argument can be one of the following
2620 option names:
2621 allexport
2622 Same as -a.
2623 errexit Same as -e.
2624 bgnice All background jobs are run at a lower priority.
2625 This is the default mode.
2626 braceexpand
2627 Same as -B.
2628 emacs Puts you in an emacs style in-line editor for
2629 command entry.
2630 globstar
2631 Same as -G.
2632 gmacs Puts you in a gmacs style in-line editor for
2633 command entry.
2634 ignoreeof
2635 The shell will not exit on end-of-file. The
2636 command exit must be used.
2637 keyword Same as -k.
2638 markdirs
2639 All directory names resulting from file name
2640 generation have a trailing / appended.
2641 monitor Same as -m.
2642 multiline
2643 The built-in editors will use multiple lines on
2644 the screen for lines that are longer than the
2645 width of the screen. This may not work for all
2646 terminals.
2647 noclobber
2648 Same as -C.
2649 noexec Same as -n.
2650 noglob Same as -f.
2651 nolog Do not save function definitions in the history
2652 file.
2653 notify Same as -b.
2654 nounset Same as -u.
2655 pipefail
2656 A pipeline will not complete until all compo‐
2657 nents of the pipeline have completed, and the
2658 return value will be the value of the last non-
2659 zero command to fail or zero if no command has
2660 failed.
2661 showme When enabled, simple commands or pipelines pre‐
2662 ceded by a semicolon (;) will be displayed as if
2663 the xtrace option were enabled but will not be
2664 executed. Otherwise, the leading ; will be
2665 ignored.
2666 privileged
2667 Same as -p.
2668 verbose Same as -v.
2669 trackall
2670 Same as -h.
2671 vi Puts you in insert mode of a vi style in-line
2672 editor until you hit the escape character 033.
2673 This puts you in control mode. A return sends
2674 the line.
2675 viraw Each character is processed as it is typed in vi
2676 mode.
2677 xtrace Same as -x.
2678 If no option name is supplied, then the current option
2679 settings are printed.
2680 -p Disables processing of the $HOME/.profile file and uses
2681 the file /etc/suid_profile instead of the ENV file.
2682 This mode is on whenever the effective uid (gid) is not
2683 equal to the real uid (gid). Turning this off causes
2684 the effective uid and gid to be set to the real uid and
2685 gid.
2686 -r Enables the restricted shell. This option cannot be
2687 unset once set.
2688 -s Sort the positional parameters lexicographically.
2689 -t (Obsolete). Exit after reading and executing one com‐
2690 mand.
2691 -u Treat unset parameters as an error when substituting.
2692 -v Print shell input lines as they are read.
2693 -x Print commands and their arguments as they are executed.
2694 -- Do not change any of the options; useful in setting $1
2695 to a value beginning with -. If no arguments follow
2696 this option then the positional parameters are unset.
2697 As an obsolete feature, if the first arg is - then the -x and -v
2699 options are turned off and the next arg is treated as the first
2700 argument. Using + rather than - causes these options to be
2701 turned off. These options can also be used upon invocation of
2702 the shell. The current set of options may be found in $-.
2703 Unless -A is specified, the remaining arguments are positional
2704 parameters and are assigned, in order, to $1 $2 .... If no
2705 arguments are given, then the names and values of all variables
2706 are printed on the standard output.
2707 † shift [ n ]
2709 The positional parameters from $n+1 ... are renamed $1 ... ,
2710 default n is 1. The parameter n can be any arithmetic expres‐
2711 sion that evaluates to a non-negative number less than or equal
2712 to $#.
2713 sleep seconds
2715 Suspends execution for the number of decimal seconds or frac‐
2716 tions of a second given by seconds.
2717 † trap [ -p ] [ action ] [ sig ] ...
2719 The -p option causes the trap action associated with each trap
2720 as specified by the arguments to be printed with appropriate
2721 quoting. Otherwise, action will be processed as if it were an
2722 argument to eval when the shell receives signal(s) sig. Each
2723 sig can be given as a number or as the name of the signal. Trap
2724 commands are executed in order of signal number. Any attempt to
2725 set a trap on a signal that was ignored on entry to the current
2726 shell is ineffective. If action is omitted and the first sig is
2727 a number, or if action is -, then the trap(s) for each sig are
2728 reset to their original values. If action is the null string
2729 then this signal is ignored by the shell and by the commands it
2730 invokes. If sig is ERR then action will be executed whenever a
2731 command has a non-zero exit status. If sig is DEBUG then action
2732 will be executed before each command. The variable .sh.command
2733 will contain the contents of the current command line when
2734 action is running. If the exit status of the trap is 2 the com‐
2735 mand will not be executed. If the exit status of the trap is
2736 255 and inside a function or a dot script, the function or dot
2737 script will return. If sig is 0 or EXIT and the trap statement
2738 is executed inside the body of a function defined with the func‐
2739 tion name syntax, then the command action is executed after the
2740 function completes. If sig is 0 or EXIT for a trap set outside
2741 any function then the command action is executed on exit from
2742 the shell. If sig is KEYBD, then action will be executed when‐
2743 ever a key is read while in emacs, gmacs, or vi mode. The trap
2744 command with no arguments prints a list of commands associated
2745 with each signal number.
2746 An exit or return without an argument in a trap action will preserve
2748 the exit status of the command that invoked the trap.
2749 true Does nothing, and exits 0. Used with while for infinite loops.
2751 true Does nothing, and exits 0. Used with while for infinite loops.
2753 †† typeset [ ±ACHSflbnprtux ] [ ±EFLRXZi[n] ] [ +-M [ mapname ] ] [
2755 -T [ tname=(assign_list) ] ] [ -h str ] [ -a [type] ] [ vname[=value ]
2756 ] ...
2757 Sets attributes and values for shell variables and functions.
2758 When invoked inside a function defined with the function name
2759 syntax, a new instance of the variable vname is created, and the
2760 variable's value and type are restored when the function com‐
2761 pletes. The following list of attributes may be specified:
2762 -A Declares vname to be an associative array. Subscripts
2763 are strings rather than arithmetic expressions.
2764 -C causes each vname to be a compound variable. value names
2765 a compound variable it is copied into vname. Otherwise,
2766 it unsets each vname.
2767 -a Declares vname to be an indexed array. If type is speci‐
2768 fied, it must be the name of an enumeration type created
2769 with the enum command and it allows enumeration constants
2770 to be used as subscripts.
2771 -E Declares vname to be a double precision floating point
2772 number. If n is non-zero, it defines the number of sig‐
2773 nificant figures that are used when expanding vname.
2774 Otherwise, ten significant figures will be used.
2775 -F Declares vname to be a double precision floating point
2776 number. If n is non-zero, it defines the number of
2777 places after the decimal point that are used when expand‐
2778 ing vname. Otherwise ten places after the decimal point
2779 will be used.
2780 -H This option provides UNIX to host-name file mapping on
2781 non-UNIX machines.
2782 -L Left justify and remove leading blanks from value. If n
2783 is non-zero, it defines the width of the field, otherwise
2784 it is determined by the width of the value of first
2785 assignment. When the variable is assigned to, it is
2786 filled on the right with blanks or truncated, if neces‐
2787 sary, to fit into the field. The -R option is turned
2788 off.
2789 -M Use the character mapping mapping defined by wctrans(3).
2790 such as tolower and toupper when assigning a value to
2791 each of the specified operands. When mapping is speci‐
2792 fied and there are not operands, all variables that use
2793 this mapping are written to standard output. When map‐
2794 ping is omitted and there are no operands, all mapped
2795 variables are written to standard output.
2796 -R Right justify and fill with leading blanks. If n is non-
2797 zero, it defines the width of the field, otherwise it is
2798 determined by the width of the value of first assignment.
2799 The field is left filled with blanks or truncated from
2800 the end if the variable is reassigned. The -L option is
2801 turned off.
2802 -S When used within the assign_list of a type definition, it
2803 causes the specified sub-variable to be shared by all
2804 instances of the type. When used inside a function
2805 defined with the function reserved word, the specified
2806 variables will have function static scope. Otherwise,
2807 the variable is unset prior to processing the assignment
2808 list.
2809 -T If followed by tname, it creates a type named by tname
2810 using the compound assignment assign_list to tname. Oth‐
2811 erwise, it writes all the type definitions to standard
2812 output.
2813 -X Declares vname to be a double precision floating point
2814 number and expands using the %a format of ISO-C99. If n
2815 is non-zero, it defines the number of hex digits after
2816 the radix point that is used when expanding vname. The
2817 default is 10.
2818 -Z Right justify and fill with leading zeros if the first
2819 non-blank character is a digit and the -L option has not
2820 been set. Remove leading zeros if the -L option is also
2821 set. If n is non-zero, it defines the width of the
2822 field, otherwise it is determined by the width of the
2823 value of first assignment.
2824 -f The names refer to function names rather than variable
2825 names. No assignments can be made and the only other
2826 valid options are -S, -t, -u and -x. The -S can be used
2827 with discipline functions defined in a type to indicate
2828 that the function is static. For a static function, the
2829 same method will be used by all instances of that type no
2830 matter which instance references it. In additon, it can
2831 only use value of variables from the original type defi‐
2832 nition. These discipline functions cannot be redefined
2833 in any type instance. The -t option turns on execution
2834 tracing for this function. The -u option causes this
2835 function to be marked undefined. The FPATH variable will
2836 be searched to find the function definition when the
2837 function is referenced. If no options other than -f is
2838 specified, then the function definition will be displayed
2839 on standard output. If +f is specified, then a line con‐
2840 taining the function name followed by a shell comment
2841 containing the line number and path name of the file
2842 where this function was defined, if any, is displayed.
2843 -b The variable can hold any number of bytes of data. The
2844 data can be text or binary. The value is represented by
2845 the base64 encoding of the data. If -Z is also speci‐
2846 fied, the size in bytes of the data in the buffer will be
2847 determined by the size associated with the -Z. If the
2848 base64 string assigned results in more data, it will be
2849 truncated. Otherwise, it will be filled with bytes whose
2850 value is zero. The printf format %B can be used to out‐
2851 put the actual data in this buffer instead of the base64
2852 encoding of the data.
2853 -h Used within type definitions to add information when gen‐
2854 erating information about the sub-variable on the man
2855 page. It is ignored when used outside of a type defini‐
2856 tion. When used with -f the information is associated
2857 with the corresponding discipline function.
2858 -i Declares vname to be represented internally as integer.
2859 The right hand side of an assignment is evaluated as an
2860 arithmetic expression when assigning to an integer. If n
2861 is non-zero, it defines the output arithmetic base, oth‐
2862 erwise the output base will be ten.
2863 -l Used with -i, -E or -F, to indicate long integer, or long
2864 float. Otherwise, all upper-case characters are con‐
2865 verted to lower-case. The upper-case option, -u, is
2866 turned off. Equivalent to -M tolower .
2867 -n Declares vname to be a reference to the variable whose
2868 name is defined by the value of variable vname. This is
2869 usually used to reference a variable inside a function
2870 whose name has been passed as an argument.
2871 -p The name, attributes and values for the given vnames are
2872 written on standard output in a form that can be used as
2873 shell input. If +p is specified, then the values are not
2874 displayed.
2875 -r The given vnames are marked readonly and these names can‐
2876 not be changed by subsequent assignment.
2877 -t Tags the variables. Tags are user definable and have no
2878 special meaning to the shell.
2879 -u When given along with -i, specifies unsigned integer.
2880 Otherwise, all lower-case characters are converted to
2881 upper-case. The lower-case option, -l, is turned off.
2882 Equivalent to -M toupper .
2883 -x The given vnames are marked for automatic export to the
2884 environment of subsequently-executed commands. Variables
2885 whose names contain a . cannot be exported.
2886 The -i attribute cannot be specified along with -R, -L, -Z, or
2888 -f.
2889 Using + rather than - causes these options to be turned off. If
2891 no vname arguments are given, a list of vnames (and optionally
2892 the values) of the variables is printed. (Using + rather than -
2893 keeps the values from being printed.) The -p option causes
2894 typeset followed by the option letters to be printed before each
2895 name rather than the names of the options. If any option other
2896 than -p is given, only those variables which have all of the
2897 given options are printed. Otherwise, the vnames and attributes
2898 of all variables that have attributes are printed.
2899 ulimit [ -HSacdfmnpstv ] [ limit ]
2901 Set or display a resource limit. The available resource limits
2902 are listed below. Many systems do not support one or more of
2903 these limits. The limit for a specified resource is set when
2904 limit is specified. The value of limit can be a number in the
2905 unit specified below with each resource, or the value unlimited.
2906 The -H and -S options specify whether the hard limit or the soft
2907 limit for the given resource is set. A hard limit cannot be
2908 increased once it is set. A soft limit can be increased up to
2909 the value of the hard limit. If neither the H nor S option is
2910 specified, the limit applies to both. The current resource
2911 limit is printed when limit is omitted. In this case, the soft
2912 limit is printed unless H is specified. When more than one
2913 resource is specified, then the limit name and unit is printed
2914 before the value.
2915 -a Lists all of the current resource limits.
2916 -c The number of 512-byte blocks on the size of core dumps.
2917 -d The number of K-bytes on the size of the data area.
2918 -f The number of 512-byte blocks on files that can be writ‐
2919 ten by the current process or by child processes (files
2920 of any size may be read).
2921 -m The number of K-bytes on the size of physical memory.
2922 -n The number of file descriptors plus 1.
2923 -p The number of 512-byte blocks for pipe buffering.
2924 -s The number of K-bytes on the size of the stack area.
2925 -t The number of CPU seconds to be used by each process.
2926 -v The number of K-bytes for virtual memory.
2927 If no option is given, -f is assumed.
2929 umask [ -S ] [ mask ]
2931 The user file-creation mask is set to mask (see umask(2)). mask
2932 can either be an octal number or a symbolic value as described
2933 in chmod(1). If a symbolic value is given, the new umask value
2934 is the complement of the result of applying mask to the comple‐
2935 ment of the previous umask value. If mask is omitted, the cur‐
2936 rent value of the mask is printed. The -S option causes the
2937 mode to be printed as a symbolic value. Otherwise, the mask is
2938 printed in octal.
2939 † unalias [ -a ] name ...
2941 The aliases given by the list of names are removed from the
2942 alias list. The -a option causes all the aliases to be unset.
2943 †unset [ -fnv ] vname ...
2945 The variables given by the list of vnames are unassigned, i.e.,
2946 except for sub-variables within a type, their values and
2947 attributes are erased. For sub-variables of a type, the values
2948 are reset to the default value from the type definition. Read‐
2949 only variables cannot be unset. If the -f option is set, then
2950 the names refer to function names. If the -v option is set,
2951 then the names refer to variable names. The -f option overrides
2952 -v. If -n is set and name is a name reference, then name will
2953 be unset rather than the variable that it references. The
2954 default is equivalent to -v. Unsetting LINENO, MAILCHECK,
2955 OPTARG, OPTIND, RANDOM, SECONDS, TMOUT, and _ removes their spe‐
2956 cial meaning even if they are subsequently assigned to.
2957 wait [ job ... ]
2959 Wait for the specified job and report its termination status.
2960 If job is not given, then all currently active child processes
2961 are waited for. The exit status from this command is that of
2962 the last process waited for if job is specified; otherwise it is
2963 zero. See Jobs for a description of the format of job.
2964 whence [ -afpv ] name ...
2966 For each name, indicate how it would be interpreted if used as a
2967 command name.
2968 The -v option produces a more verbose report. The -f option
2969 skips the search for functions. The -p option does a path
2970 search for name even if name is an alias, a function, or a
2971 reserved word. The -p option turns off the -v option. The -a
2972 option is similar to the -v option but causes all interpreta‐
2973 tions of the given name to be reported.
2974 Invocation.
2976 If the shell is invoked by exec(2), and the first character of argument
2977 zero ($0) is -, then the shell is assumed to be a login shell and com‐
2978 mands are read from /etc/profile and then from either .profile in the
2979 current directory or $HOME/.profile, if either file exists. Next, for
2980 interactive shells, commands are read from the file named by performing
2981 parameter expansion, command substitution, and arithmetic substitution
2982 on the value of the environment variable ENV if the file exists. If
2983 the -s option is not present and arg and a file by the name of arg
2984 exists, then it reads and executes this script. Otherwise, if the
2985 first arg does not contain a /, a path search is performed on the first
2986 arg to determine the name of the script to execute. The script arg
2987 must have execute permission and any setuid and setgid settings will be
2988 ignored. If the script is not found on the path, arg is processed as
2989 if it named a built-in command or function. Commands are then read as
2990 described below; the following options are interpreted by the shell
2991 when it is invoked:
2992 -D Do not execute the script, but output the set of double quoted
2994 strings preceded by a $. These strings are needed for local‐
2995 ization of the script to different locales.
2996 -E Reads the file named by the ENV variable or by $HOME/.kshrc if
2997 not defined after the profiles.
2998 -c If the -c option is present, then commands are read from the
2999 first arg. Any remaining arguments become positional parame‐
3000 ters starting at 0.
3001 -s If the -s option is present or if no arguments remain, then
3002 commands are read from the standard input. Shell output,
3003 except for the output of the Special Commands listed above,
3004 is written to file descriptor 2.
3005 -i If the -i option is present or if the shell input and output
3006 are attached to a terminal (as told by tcgetattr(2)), then
3007 this shell is interactive. In this case TERM is ignored (so
3008 that kill 0 does not kill an interactive shell) and INTR is
3009 caught and ignored (so that wait is interruptible). In all
3010 cases, QUIT is ignored by the shell.
3011 -r If the -r option is present, the shell is a restricted shell.
3012 -D A list of all double quoted strings that are preceded by a $
3013 will be printed on standard output and the shell will exit.
3014 This set of strings will be subject to language translation
3015 when the locale is not C or POSIX. No commands will be exe‐
3016 cuted.
3017 -P If -P or -o profile is present, the shell is a profile shell
3019 (see pfexec(1)).
3020 -R filename
3022 The -R filename option is used to generate a cross reference
3023 database that can be used by a separate utility to find defi‐
3024 nitions and references for variables and commands.
3025 The remaining options and arguments are described under the set command
3027 above. An optional - as the first argument is ignored.
3028 Rksh Only.
3030 Rksh is used to set up login names and execution environments whose
3031 capabilities are more controlled than those of the standard shell. The
3032 actions of rksh are identical to those of ksh, except that the follow‐
3033 ing are disallowed:
3034 Unsetting the restricted option.
3035 changing directory (see cd(1)),
3036 setting or unsetting the value or attributes of SHELL, ENV,
3037 FPATH, or PATH,
3038 specifying path or command names containing /,
3039 redirecting output (>, >|, <>, and >>).
3040 adding or deleting built-in commands.
3041 using command -p to invoke a command.
3042 The restrictions above are enforced after .profile and the ENV files
3044 are interpreted.
3045 When a command to be executed is found to be a shell procedure, rksh
3047 invokes ksh to execute it. Thus, it is possible to provide to the end-
3048 user shell procedures that have access to the full power of the stan‐
3049 dard shell, while imposing a limited menu of commands; this scheme
3050 assumes that the end-user does not have write and execute permissions
3051 in the same directory.
3052 The net effect of these rules is that the writer of the .profile has
3054 complete control over user actions, by performing guaranteed setup
3055 actions and leaving the user in an appropriate directory (probably not
3056 the login directory).
3057 The system administrator often sets up a directory of commands (e.g.,
3059 /usr/rbin) that can be safely invoked by rksh.
3060
3062 Errors detected by the shell, such as syntax errors, cause the shell to
3063 return a non-zero exit status. If the shell is being used non-interac‐
3064 tively, then execution of the shell file is abandoned unless the error
3065 occurs inside a subshell in which case the subshell is abandoned. Oth‐
3066 erwise, the shell returns the exit status of the last command executed
3067 (see also the exit command above). Run time errors detected by the
3068 shell are reported by printing the command or function name and the
3069 error condition. If the line number that the error occurred on is
3070 greater than one, then the line number is also printed in square brack‐
3071 ets ([]) after the command or function name.
3072
3074 /etc/profile
3075 The system wide initialization file, executed for login shells.
3076 $HOME/.profile
3078 The personal initialization file, executed for login shells
3079 after /etc/profile.
3080 $HOME/..kshrc
3082 Default personal initialization file, executed for interactive
3083 shells when ENV is not set.
3084 /etc/suid_profile
3086 Alternative initialization file, executed instead of the per‐
3087 sonal initialization file when the real and effective user or
3088 group id do not match.
3089 /dev/null
3091 NULL device
3092
3094 cat(1), cd(1), chmod(1), cut(1), egrep(1), echo(1), emacs(1), env(1),
3095 fgrep(1), gmacs(1), grep(1), newgrp(1), pfexec(1), stty(1), test(1),
3096 umask(1), vi(1), dup(2), exec(2), fork(2), getpwnam(3), ioctl(2),
3097 lseek(2), paste(1), pathconf(2), pipe(2), sysconf(2), umask(2),
3098 ulimit(2), wait(2), wctrans(3), rand(3), a.out(5), profile(5), envi‐
3099 ron(7).
3100 Morris I. Bolsky and David G. Korn, The New KornShell Command and Pro‐
3102 gramming Language, Prentice Hall, 1995.
3103 POSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC
3105 9945-2, IEEE, 1993.
3106
3108 If a command is executed, and then a command with the same name is
3109 installed in a directory in the search path before the directory where
3110 the original command was found, the shell will continue to exec the
3111 original command. Use the -t option of the alias command to correct
3112 this situation.
3113 Some very old shell scripts contain a ^ as a synonym for the pipe char‐
3115 acter ⎪.
3116 Using the hist built-in command within a compound command will cause
3118 the whole command to disappear from the history file.
3119 The built-in command . file reads the whole file before any commands
3121 are executed. Therefore, alias and unalias commands in the file will
3122 not apply to any commands defined in the file.
3123 Traps are not processed while a job is waiting for a foreground
3125 process. Thus, a trap on CHLD won't be executed until the foreground
3126 job terminates.
3127 It is a good idea to leave a space after the comma operator in arith‐
3129 metic expressions to prevent the comma from being interpreted as the
3130 decimal point character in certain locales.
3131RDS Standard User Environment Utilities KSH(1)