1KSH(1) General Commands Manual KSH(1)
2
6 ksh, rksh - KornShell, a standard/restricted command and programming
7 language
8
10 ksh [ ±abcefhiklmnprstuvxBCDEGH ] [ ±o option ] ... [ - ] [ arg ... ]
11 rksh [ ±abcefhiklmnpstuvxBCDEGH ] [ ±o option ] ... [ - ] [ arg ... ]
12
14 Ksh is a command and programming language that executes commands read
15 from a terminal or a file. Rksh is a restricted version of the command
16 interpreter ksh; it is used to set up login names and execution envi‐
17 ronments whose capabilities are more controlled than those of the stan‐
18 dard shell. See Invocation below for the meaning of arguments to the
19 shell.
20 Definitions.
22 A metacharacter is one of the following characters:
23 ; & ( ) | < > new-line space tab
25 A blank is a tab or a space. An identifier is a sequence of letters,
27 digits, or underscores starting with a letter or underscore. Identi‐
28 fiers are used as components of variable names. A vname is a sequence
29 of one or more identifiers separated by a . and optionally preceded by
30 a .. Vnames are used as function and variable names. A word is a se‐
31 quence of characters from the character set defined by the current lo‐
32 cale, excluding non-quoted metacharacters.
33 A command is a sequence of characters in the syntax of the shell lan‐
35 guage. The shell reads each command and carries out the desired action
36 either directly or by invoking separate utilities. A built-in command
37 is a command that is carried out by the shell itself without creating a
38 separate process. Some commands are built-in purely for convenience
39 and are not documented here. Built-ins that cause side effects in the
40 shell environment and built-ins that are found before performing a path
41 search (see Execution below) are documented here. For historical rea‐
42 sons, some of these built-ins behave differently than other built-ins
43 and are called special built-ins.
44 Commands.
46 A simple-command is a list of variable assignments (see Variable As‐
47 signments below) or a sequence of blank separated words which may be
48 preceded by a list of variable assignments (see Environment below).
49 The first word specifies the name of the command to be executed. Ex‐
50 cept as specified below, the remaining words are passed as arguments to
51 the invoked command. The command name is passed as argument 0 (see
52 exec(2)). The value of a simple-command is its exit status; 0-255 if
53 it terminates normally; 256+signum if it terminates abnormally (the
54 name of the signal corresponding to the exit status can be obtained via
55 the -l option of the kill built-in utility).
56 A pipeline is a sequence of one or more commands separated by |. The
58 standard output of each command but the last is connected by a pipe(2)
59 to the standard input of the next command. Each command, except possi‐
60 bly the last, is run as a separate process; the shell waits for the
61 last command to terminate. The exit status of a pipeline is the exit
62 status of the last command unless the pipefail option is enabled. Each
63 pipeline can be preceded by the reserved word ! which causes the exit
64 status of the pipeline to become 0 if the exit status of the last com‐
65 mand is non-zero, and 1 if the exit status of the last command is 0.
66 A list is a sequence of one or more pipelines separated by ;, &, |&,
68 &&, or ||, and optionally terminated by ;, &, or |&. Of these five
69 symbols, ;, &, and |& have equal precedence, which is lower than that
70 of && and ||. The symbols && and || also have equal precedence. A
71 semicolon (;) causes sequential execution of the preceding pipeline; an
72 ampersand (&) causes asynchronous execution of the preceding pipeline
73 (i.e., the shell does not wait for that pipeline to finish). The sym‐
74 bol |& causes asynchronous execution of the preceding pipeline with a
75 two-way pipe established to the parent shell; the standard input and
76 output of the spawned pipeline can be written to and read from by the
77 parent shell by applying the redirection operators <& and >& with arg p
78 to commands and by using -p option of the built-in commands read and
79 print described later. The symbol && (||) causes the list following it
80 to be executed only if the preceding pipeline returns a zero (non-zero)
81 value. One or more new-lines may appear in a list instead of a semi‐
82 colon, to delimit a command. The first item of the first pipeline of
83 a list that is a simple command not beginning with a redirection, and
84 not occurring within a while, until, or if list, can be preceded by a
85 semicolon. This semicolon is ignored unless the showme option is en‐
86 abled as described with the set built-in below.
87 A command is either a simple-command or one of the following. Unless
89 otherwise stated, the value returned by a command is that of the last
90 simple-command executed in the command.
91 for vname [ in word ... ] ;do list ;done
93 Each time a for command is executed, vname is set to the next
94 word taken from the in word list. If in word ... is omitted,
95 then the for command executes the do list once for each posi‐
96 tional parameter that is set starting from 1 (see Parameter Ex‐
97 pansion below). Execution ends when there are no more words in
98 the list.
99 for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
101 The arithmetic expression expr1 is evaluated first (see Arith‐
102 metic evaluation below). The arithmetic expression expr2 is re‐
103 peatedly evaluated until it evaluates to zero and when non-zero,
104 list is executed and the arithmetic expression expr3 evaluated.
105 If any expression is omitted, then it behaves as if it evaluated
106 to 1.
107 select vname [ in word ... ] ;do list ;done
109 A select command prints on standard error (file descriptor 2)
110 the set of words, each preceded by a number. If in word ... is
111 omitted, then the positional parameters starting from 1 are used
112 instead (see Parameter Expansion below). The PS3 prompt is
113 printed and a line is read from the standard input. If this
114 line consists of the number of one of the listed words, then the
115 value of the variable vname is set to the word corresponding to
116 this number. If this line is empty, the selection list is
117 printed again. Otherwise the value of the variable vname is set
118 to null. The contents of the line read from standard input is
119 saved in the variable REPLY. The list is executed for each se‐
120 lection until a break or end-of-file is encountered. If the RE‐
121 PLY variable is set to null by the execution of list, then the
122 selection list is printed before displaying the PS3 prompt for
123 the next selection.
124 case word in [ [(]pattern [ | pattern ] ... ) list ;; ] ... esac
126 A case command executes the list associated with the first pat‐
127 tern that matches word. The form of the patterns is the same as
128 that used for file name generation (see File Name Generation be‐
129 low). The ;; operator causes execution of case to terminate.
130 If ;& is used in place of ;; the next subsequent list, if any,
131 is executed.
132 if list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi
134 The list following if is executed and, if it returns a zero exit
135 status, the list following the first then is executed. Other‐
136 wise, the list following elif is executed and, if its value is
137 zero, the list following the next then is executed. Failing
138 each successive elif list, the else list is executed. If the if
139 list has non-zero exit status and there is no else list, then
140 the if command returns a zero exit status.
141 while list ;do list ;done
143 until list ;do list ;done
144 A while command repeatedly executes the while list and, if the
145 exit status of the last command in the list is zero, executes
146 the do list; otherwise the loop terminates. If no commands in
147 the do list are executed, then the while command returns a zero
148 exit status; until may be used in place of while to negate the
149 loop termination test.
150 ((expression))
152 The expression is evaluated using the rules for arithmetic eval‐
153 uation described below. If the value of the arithmetic expres‐
154 sion is non-zero, the exit status is 0, otherwise the exit sta‐
155 tus is 1.
156 (list)
158 Execute list in a separate environment. Note, that if two adja‐
159 cent open parentheses are needed for nesting, a space must be
160 inserted to avoid evaluation as an arithmetic command as de‐
161 scribed above.
162 { list;}
164 list is simply executed. Note that unlike the metacharacters (
165 and ), { and } are reserved words and must occur at the begin‐
166 ning of a line or after a ; in order to be recognized.
167 [[ expression ]]
169 Evaluates expression and returns a zero exit status when expres‐
170 sion is true. See Conditional Expressions below, for a descrip‐
171 tion of expression.
172 function varname { list ;}
174 varname () { list ;}
175 Define a function which is referenced by varname. A function
176 whose varname contains a . is called a discipline function and
177 the portion of the varname preceding the last . must refer to
178 an existing variable. The body of the function is the list of
179 commands between { and }. A function defined with the function
180 varname syntax can also be used as an argument to the . special
181 built-in command to get the equivalent behavior as if the var‐
182 name() syntax were used to define it. (See Functions below.)
183 namespace identifier { list ;}
185 Defines or uses the name space identifier and runs the commands
186 in list in this name space. (See Name Spaces below.)
187 & [ name [ arg... ] ]
189 Causes subsequent list commands terminated by & to be placed in
190 the background job pool name. If name is omitted a default un‐
191 named pool is used. Commands in a named background pool may be
192 executed remotely.
193 time [ pipeline ]
195 If pipeline is omitted the user and system time for the current
196 shell and completed child processes is printed on standard er‐
197 ror. Otherwise, pipeline is executed and the elapsed time as
198 well as the user and system time are printed on standard error.
199 The TIMEFORMAT variable may be set to a format string that spec‐
200 ifies how the timing information should be displayed. See Shell
201 Variables below for a description of the TIMEFORMAT variable.
202 The following reserved words are recognized as reserved only when they
204 are the first word of a command and are not quoted:
205 if then else elif fi case esac for while until do done { } function se‐
207 lect time [[ ]] !
208 Variable Assignments.
210 One or more variable assignments can start a simple command or can be
211 arguments to the typeset, enum, export, or readonly special built-in
212 commands as well as to other declaration commands created as types.
213 The syntax for an assignment is of the form:
214 varname=word
216 varname[word]=word
217 No space is permitted between varname and the = or between = and
218 word.
219 varname=(assign_list)
221 No space is permitted between varname and the =. The variable
222 varname is unset before the assignment. An assign_list can be
223 one of the following:
224 word ...
225 Indexed array assignment.
226 [word]=word ...
227 Associative array assignment. If preceded by
228 typeset -a this will create an indexed array in‐
229 stead.
230 assignment ...
231 Compound variable assignment. This creates a
232 compound variable varname with sub-variables of
233 the form varname.name, where name is the name
234 portion of assignment. The value of varname will
235 contain all the assignment elements. Additional
236 assignments made to sub-variables of varname will
237 also be displayed as part of the value of var‐
238 name. If no assignments are specified, varname
239 will be a compound variable allowing subsequence
240 child elements to be defined.
241 typeset [options] assignment ...
242 Nested variable assignment. Multiple assignments
243 can be specified by separating each of them with
244 a ;. The previous value is unset before the as‐
245 signment. Other declaration commands such as
246 readonly, enum, and other declaration commands
247 can be used in place of typeset.
248 . filename
249 Include the assignment commands contained in
250 filename.
251 In addition, a += can be used in place of the = to signify adding to or
253 appending to the previous value. When += is applied to an arithmetic
254 type, word is evaluated as an arithmetic expression and added to the
255 current value. When applied to a string variable, the value defined by
256 word is appended to the value. For compound assignments, the previous
257 value is not unset and the new values are appended to the current ones
258 provided that the types are compatible.
259 The right hand side of a variable assignment undergoes all the expan‐
261 sion listed below except word splitting, brace expansion, and file name
262 generation. When the left hand side is an assignment is a compound
263 variable and the right hand is the name of a compound variable, the
264 compound variable on the right will be copied or appended to the com‐
265 pound variable on the left.
266 Comments.
268 A word beginning with # causes that word and all the following charac‐
269 ters up to a new-line to be ignored.
270 Aliasing.
272 The first word of each command is replaced by the text of an alias if
273 an alias for this word has been defined. An alias name consists of any
274 number of characters excluding metacharacters, quoting characters, file
275 expansion characters, parameter expansion and command substitution
276 characters, the characters / and =. The replacement string can contain
277 any valid shell script including the metacharacters listed above. The
278 first word of each command in the replaced text, other than any that
279 are in the process of being replaced, will be tested for aliases. If
280 the last character of the alias value is a blank then the word follow‐
281 ing the alias will also be checked for alias substitution. Aliases can
282 be used to redefine built-in commands but cannot be used to redefine
283 the reserved words listed above. Aliases can be created and listed
284 with the alias command and can be removed with the unalias command.
285 Aliasing is performed when scripts are read, not while they are exe‐
287 cuted. Therefore, for an alias to take effect, the alias definition
288 command has to be executed before the command which references the
289 alias is read.
290 The following aliases are automatically preset when the shell is in‐
292 voked as an interactive shell, unless invoked in POSIX compliance mode
293 (see Invocation below). Preset aliases can be unset or redefined.
294 history=′hist -l′
295 r=′hist -s′
296 Tilde Expansion.
298 After alias substitution is performed, each word is checked to see if
299 it begins with an unquoted ∼. For tilde expansion, word also refers to
300 the word portion of parameter expansion (see Parameter Expansion be‐
301 low). If a word is preceded by a tilde, then it is checked up to a /
302 to see if it matches a user name in the password database (see getpw‐
303 name(3)). If a match is found, the ∼ and the matched login name are
304 replaced by the login directory of the matched user. If no match is
305 found, the original text is left unchanged. A ∼ by itself, or in front
306 of a /, is replaced by $HOME, unless the HOME variable is unset, in
307 which case the current user's home directory as configured in the oper‐
308 ating system is used. A ∼ followed by a + or - is replaced by $PWD or
309 $OLDPWD respectively.
310 In addition, when expanding a variable assignment (see Variable Assign‐
312 ments above), tilde expansion is attempted when the value of the as‐
313 signment begins with a ∼, and when a ∼ appears after a :. A : also
314 terminates a user name following a ∼.
315 The tilde expansion mechanism may be extended or modified by defining
317 one of the discipline functions .sh.tilde.set or .sh.tilde.get (see
318 Functions and Discipline Functions below). If either exists, then upon
319 encountering a tilde word to expand, that function is called with the
320 tilde word assigned to either .sh.value (for the .sh.tilde.set func‐
321 tion) or .sh.tilde (for the .sh.tilde.get function). Performing tilde
322 expansion within a discipline function will not recursively call that
323 function, but default tilde expansion remains active, so literal tildes
324 should still be quoted where required. Either function may assign a
325 replacement string to .sh.value. If this value is non-empty and does
326 not start with a ∼, it replaces the default tilde expansion when the
327 function terminates. Otherwise, the tilde expansion is left unchanged.
328 Command Substitution.
330 The standard output from a command list enclosed in parentheses pre‐
331 ceded by a dollar sign ( $(list) ), or in a brace group preceded by a
332 dollar sign ( ${ list;} ), or in a pair of grave accents (``) may be
333 used as part or all of a word; trailing new-lines are removed. In the
334 second case, the { and } are treated as a reserved words so that { must
335 be followed by a blank and } must appear at the beginning of the line
336 or follow a ;. In the third (obsolete) form, the string between the
337 quotes is processed for special quoting characters before the command
338 is executed (see Quoting below). The command substitution $(cat file)
339 can be replaced by the equivalent but faster $(<file). The command
340 substitution $(n<#) will expand to the current byte offset for file de‐
341 scriptor n. Except for the second form, the command list is run in a
342 subshell so that no side effects are possible. For the second form,
343 the final } will be recognized as a reserved word after any token.
344 Arithmetic Substitution.
346 An arithmetic expression enclosed in double parentheses preceded by a
347 dollar sign ( $(()) ) is replaced by the value of the arithmetic ex‐
348 pression within the double parentheses.
349 Process Substitution.
351 Each command argument of the form <(list) or >(list) will run process
352 list asynchronously connected to some file in /dev/fd if this directory
353 exists, or else a fifo a temporary directory. The name of this file
354 will become the argument to the command. If the form with > is se‐
355 lected then writing on this file will provide input for list. If < is
356 used, then the file passed as an argument will contain the output of
357 the list process. For example,
358 paste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1)
360 >(process2)
361 cuts fields 1 and 3 from the files file1 and file2 respectively, pastes
363 the results together, and sends it to the processes process1 and
364 process2, as well as putting it onto the standard output. Note that
365 the file, which is passed as an argument to the command, is a UNIX
366 pipe(2) so programs that expect to lseek(2) on the file will not work.
367 Process substitution of the form <(list) can also be used with the <
369 redirection operator which causes the output of list to be standard in‐
370 put or the input for whatever file descriptor is specified.
371 Parameter Expansion.
373 A parameter is a variable, one or more digits, or any of the characters
374 *, @, #, ?, -, $, and !. A variable is denoted by a vname. To create
375 a variable whose vname contains a ., a variable whose vname consists of
376 everything before the last . must already exist. A variable has a
377 value and zero or more attributes. Variables can be assigned values
378 and attributes by using the typeset special built-in command. The at‐
379 tributes supported by the shell are described later with the typeset
380 special built-in command. Exported variables pass their attributes to
381 the environment so that a newly invoked ksh that is a child or exec'ed
382 process of the current shell will automatically import them, unless the
383 posix shell option is on.
384 The shell supports both indexed and associative arrays. An element of
386 an array variable is referenced by a subscript. A subscript for an in‐
387 dexed array is denoted by an arithmetic expression (see Arithmetic
388 evaluation below) between a [ and a ]. To assign values to an indexed
389 array, use vname=(value ...) or set -A vname value ... . The value of
390 all non-negative subscripts must be in the range of 0 through
391 4,194,303. A negative subscript is treated as an offset from the maxi‐
392 mum current index +1 so that -1 refers to the last element. Indexed
393 arrays can be declared with the -a option to typeset. Indexed arrays
394 need not be declared. Any reference to a variable with a valid sub‐
395 script is legal and an array will be created if necessary.
396 An associative array is created with the -A option to typeset. A sub‐
398 script for an associative array is denoted by a string enclosed between
399 [ and ].
400 Referencing any array without a subscript is equivalent to referencing
402 the array with subscript 0.
403 The value of a variable may be assigned by writing:
405 vname=value [ vname=value ] ...
407 or
409 vname[subscript]=value [ vname[subscript]=value ] ...
410 Note that no space is allowed before or after the =.
411 Attributes assigned by the typeset special built-in command apply to
412 all elements of the array. An array element can be a simple variable,
413 a compound variable or an array variable. An element of an indexed ar‐
414 ray can be either an indexed array or an associative array. An element
415 of an associative array can also be either. To refer to an array ele‐
416 ment that is part of an array element, concatenate the subscript in
417 brackets. For example, to refer to the foobar element of an associa‐
418 tive array that is defined as the third element of the indexed array,
419 use ${vname[3][foobar]}
420 A nameref is a variable that is a reference to another variable. A
421 nameref is created with the -n attribute of typeset. The value of the
422 variable at the time of the typeset command becomes the variable that
423 will be referenced whenever the nameref variable is used. The name of
424 a nameref cannot contain a .. When a variable or function name con‐
425 tains a ., and the portion of the name up to the first . matches the
426 name of a nameref, the variable referred to is obtained by replacing
427 the nameref portion with the name of the variable referenced by the
428 nameref. If a nameref is used as the index of a for loop, a name ref‐
429 erence is established for each item in the list. A nameref provides a
430 convenient way to refer to the variable inside a function whose name is
431 passed as an argument to a function. For example, if the name of a
432 variable is passed as the first argument to a function, the command
433 typeset -n var=$1
434 inside the function causes references and assignments to var to be ref‐
435 erences and assignments to the variable whose name has been passed to
436 the function.
437 If any of the floating point attributes, -E, -F, or -X, or the integer
438 attribute, -i, is set for vname, then the value is subject to arith‐
439 metic evaluation as described below.
440 Positional parameters, parameters denoted by a number, may be assigned
441 values with the set special built-in command. Parameter $0 is set from
442 argument zero when the shell is invoked.
443 The character $ is used to introduce substitutable parameters.
444 ${parameter}
445 The shell reads all the characters from ${ to the matching } as
446 part of the same word even if it contains braces or metacharac‐
447 ters. The value, if any, of the parameter is substituted. The
448 braces are required when parameter is followed by a letter,
449 digit, or underscore that is not to be interpreted as part of
450 its name, when the variable name contains a .. The braces are
451 also required when a variable is subscripted unless it is part
452 of an Arithmetic Expression or a Conditional Expression. If pa‐
453 rameter is one or more digits then it is a positional parameter.
454 A positional parameter of more than one digit must be enclosed
455 in braces. If parameter is * or @, then all the positional pa‐
456 rameters, starting with $1, are substituted (separated by a
457 field separator character). If an array vname with last sub‐
458 script * @, or for indexed arrays of the form sub1 .. sub2. is
459 used, then the value for each of the elements between sub1 and
460 sub2 inclusive (or all elements for * and @) is substituted,
461 separated by the first character of the value of IFS.
462 ${#parameter}
463 If parameter is * or @, the number of positional parameters is
464 substituted. Otherwise, the length of the value of the parame‐
465 ter is substituted.
466 ${#vname[*]}
467 ${#vname[@]}
468 The number of elements in the array vname is substituted.
469 ${@vname}
471 Expands to the type name (See Type Variables below) or at‐
472 tributes of the variable referred to by vname.
473 ${!vname}
474 Expands to the name of the variable referred to by vname. This
475 will be vname except when vname is a name reference.
476 ${!vname[subscript]}
477 Expands to name of the subscript unless subscript is *, @. or
478 of the form sub1 .. sub2. When subscript is *, the list of ar‐
479 ray subscripts for vname is generated. For a variable that is
480 not an array, the value is 0 if the variable is set. Otherwise
481 it is null. When subscript is @, same as above, except that
482 when used in double quotes, each array subscript yields a sepa‐
483 rate argument. When subscript is of the form sub1 .. sub2 it
484 expands to the list of subscripts between sub1 and sub2 inclu‐
485 sive using the same quoting rules as @.
486 ${!prefix@}
487 ${!prefix*}
488 These both expand to the names of the variables whose names be‐
489 gin with prefix. The expansions otherwise work like $@ and $*,
490 respectively (see under Quoting below).
491 ${parameter:-word}
492 If parameter is set and is non-null then substitute its value;
493 otherwise substitute word.
494 ${parameter:=word}
495 If parameter is not set or is null then set it to word; the
496 value of the parameter is then substituted. Positional parame‐
497 ters may not be assigned to in this way.
498 ${parameter:?word}
499 If parameter is set and is non-null then substitute its value;
500 otherwise, print word and exit from the shell (if not interac‐
501 tive). If word is omitted then a standard message is printed.
502 ${parameter:+word}
503 If parameter is set and is non-null then substitute word; other‐
504 wise substitute nothing.
505 In the above, word is not evaluated unless it is to be used as the sub‐
506 stituted string, so that, in the following example, pwd is executed
507 only if d is not set or is null:
508 print ${d:-$(pwd)}
509 If the colon ( : ) is omitted from the above expressions, then the
510 shell only checks whether parameter is set or not.
511 ${parameter:offset:length}
512 ${parameter:offset}
513 Expands to the portion of the value of parameter starting at the
514 character (counting from 0) determined by expanding offset as an
515 arithmetic expression and consisting of the number of characters
516 determined by the arithmetic expression defined by length. In
517 the second form, the remainder of the value is used. If A nega‐
518 tive offset counts backwards from the end of parameter. Note
519 that one or more blanks is required in front of a minus sign to
520 prevent the shell from interpreting the operator as :-. If pa‐
521 rameter is * or @, or is an array name indexed by * or @, then
522 offset and length refer to the array index and number of ele‐
523 ments respectively. A negative offset is taken relative to one
524 greater than the highest subscript for indexed arrays. The or‐
525 der for associative arrays is unspecified.
526 ${parameter#pattern}
527 ${parameter##pattern}
528 If the shell pattern matches the beginning of the value of pa‐
529 rameter, then the value of this expansion is the value of the
530 parameter with the matched portion deleted; otherwise the value
531 of this parameter is substituted. In the first form the small‐
532 est matching pattern is deleted and in the second form the
533 largest matching pattern is deleted. When parameter is @, *, or
534 an array variable with subscript @ or *, the substring operation
535 is applied to each element in turn.
536 ${parameter%pattern}
538 ${parameter%%pattern}
539 If the shell pattern matches the end of the value of parameter,
540 then the value of this expansion is the value of the parameter
541 with the matched part deleted; otherwise substitute the value of
542 parameter. In the first form the smallest matching pattern is
543 deleted and in the second form the largest matching pattern is
544 deleted. When parameter is @, *, or an array variable with sub‐
545 script @ or *, the substring operation is applied to each ele‐
546 ment in turn.
547 ${parameter/pattern/string}
549 ${parameter//pattern/string}
550 ${parameter/#pattern/string}
551 ${parameter/%pattern/string}
552 Expands parameter and replaces the longest match of pattern with
553 the given string. Each occurrence of \n in string is replaced
554 by the portion of parameter that matches the n-th sub-pattern.
555 In the first form, only the first occurrence of pattern is re‐
556 placed. In the second form, each match for pattern is replaced
557 by the given string. The third form restricts the pattern match
558 to the beginning of the string while the fourth form restricts
559 the pattern match to the end of the string. When string is
560 null, the pattern will be deleted and the / in front of string
561 may be omitted. When parameter is @, *, or an array variable
562 with subscript @ or *, the substitution operation is applied to
563 each element in turn. In this case, the string portion of word
564 will be re-evaluated for each element.
565 The following parameters are automatically set by the shell:
567 # The number of positional parameters in decimal.
568 - Options supplied to the shell on invocation or by the set
569 command.
570 ? The decimal value returned by the last executed command.
571 $ The process id of this shell.
572 _ Initially, the value of _ is an absolute pathname of the
573 shell or script being executed as passed in the environ‐
574 ment. Subsequently it is assigned the last argument of
575 the previous command. This parameter is not set for com‐
576 mands which are asynchronous. This parameter is also
577 used to hold the name of the matching MAIL file when
578 checking for mail. While defining a compound variable or
579 a type, _ is initialized as a reference to the compound
580 variable or type. When a discipline function is invoked,
581 _ is initialized as a reference to the variable associ‐
582 ated with the call to this function. Finally when _ is
583 used as the name of the first variable of a type defini‐
584 tion, the new type is derived from the type of the first
585 variable. (See Type Variables below.)
586 ! The process id or the pool name and job number of the
587 last background command invoked or the most recent job
588 put in the background with the bg built-in command.
589 Background jobs started in a named pool will be in the
590 form pool.number where pool is the pool name and number
591 is the job number within that pool.
592 .sh.command
593 When processing a DEBUG trap, this variable contains the
594 current command line that is about to run. Each argument
595 is shell-quoted as necessary so that the value is safe
596 for being evaluated by the shell.
597 .sh.edchar
598 This variable contains the value of the keyboard charac‐
599 ter (or sequence of characters if the first character is
600 an ESC, ascii 033) that has been entered when processing
601 a KEYBD trap (see Key Bindings below). If the value is
602 changed as part of the trap action, then the new value
603 replaces the key (or key sequence) that caused the trap.
604 .sh.edcol
605 The character position of the cursor at the time of the
606 most recent KEYBD trap.
607 .sh.edmode
608 The value is set to ESC when processing a KEYBD trap
609 while in vi insert mode. (See Vi Editing Mode below.)
610 Otherwise, .sh.edmode is null when processing a KEYBD
611 trap.
612 .sh.edtext
613 The characters in the input buffer at the time of the
614 most recent KEYBD trap. The value is null when not pro‐
615 cessing a KEYBD trap.
616 .sh.file
617 The pathname of the file that contains the current com‐
618 mand.
619 .sh.fun
620 The name of the current function that is being executed.
621 .sh.level
622 Set to the current function depth. This can be changed
623 inside a DEBUG trap and will set the context to the spec‐
624 ified level.
625 .sh.lineno
626 Set during a DEBUG trap to the line number for the caller
627 of each function.
628 .sh.match
629 An indexed array which stores the most recent match and
630 sub-pattern matches after conditional pattern matches
631 that match and after variables expansions using the oper‐
632 ators #, %, or /. The 0-th element stores the complete
633 match and the i-th. element stores the i-th submatch.
634 The .sh.match variable becomes unset when the variable
635 that has expanded is assigned a new value.
636 .sh.math
637 Used for defining arithmetic functions (see Arithmetic
638 evaluation below) and stores the list of user defined
639 arithmetic functions.
640 .sh.name
641 Set to the name of the variable at the time that a disci‐
642 pline function is invoked.
643 .sh.subscript
644 Set to the name subscript of the variable at the time
645 that a discipline function is invoked.
646 .sh.subshell
647 The current depth for subshells and command substitution.
648 .sh.pid
649 Set to the process ID of the current shell. This is dis‐
650 tinct from $$ as in forked subshells this is set to the
651 process ID of the subshell instead of the parent shell's
652 process ID. In virtual subshells .sh.pid retains its
653 previous value.
654 .sh.value
655 Set to the value of the variable at the time that the set
656 or append discipline function is invoked. When a user
657 defined arithmetic function is invoked, the value of
658 .sh.value is saved and .sh.value is set to long double
659 precision floating point. .sh.value is restored when the
660 function returns.
661 .sh.version
662 Set to a value that identifies the version of this shell.
663 KSH_VERSION
664 A name reference to .sh.version.
665 LINENO The current line number within the script or function be‐
666 ing executed.
667 OLDPWD The previous working directory set by the cd command.
668 OPTARG The value of the last option argument processed by the
669 getopts built-in command.
670 OPTIND The index of the last option argument processed by the
671 getopts built-in command.
672 PPID The process id of the parent of the shell.
673 PWD The present working directory set by the cd command.
674 RANDOM Each time this variable is referenced, a random integer,
675 uniformly distributed between 0 and 32767, is generated.
676 The sequence of random numbers can be initialized by as‐
677 signing a numeric value to RANDOM.
678 REPLY This variable is set by the select statement and by the
679 read built-in command when no arguments are supplied.
680 SECONDS
681 Each time this variable is referenced, the number of sec‐
682 onds since shell invocation is returned. If this vari‐
683 able is assigned a value, then the value returned upon
684 reference will be the value that was assigned plus the
685 number of seconds since the assignment.
686 SHLVL An integer variable the is incremented each time the
687 shell is invoked and is exported. If SHLVL is not in the
688 environment when the shell is invoked, it is set to 1.
689 The following variables are used by the shell:
691 CDPATH The search path for the cd command.
692 COLUMNS
693 If this variable is set, the value is used to define the
694 width of the edit window for the shell edit modes and for
695 printing select lists.
696 EDITOR If the VISUAL variable is not set, the value of this
697 variable will be checked for the patterns as described
698 with VISUAL below and the corresponding editing option
699 (see Special Command set below) will be turned on.
700 ENV If this variable is set, then parameter expansion, com‐
701 mand substitution, and arithmetic substitution are per‐
702 formed on the value to generate the pathname of the
703 script that will be executed when the shell is invoked
704 interactively (see Invocation below). This file is typi‐
705 cally used for alias and function definitions. The de‐
706 fault value is $HOME/.kshrc. On systems that support a
707 system wide /etc/ksh.kshrc initialization file, if the
708 filename generated by the expansion of ENV begins with
709 /./ or ././ the system wide initialization file will not
710 be executed.
711 FCEDIT Obsolete name for the default editor name for the hist
712 command. FCEDIT is not used when HISTEDIT is set.
713 FIGNORE
714 A pattern that defines the set of filenames that will be
715 ignored when performing filename matching.
716 FPATH The search path for function definitions. The directo‐
717 ries in this path are searched for a file with the same
718 name as the function or command when a function with the
719 -u attribute is referenced and when a command is not
720 found. If an executable file with the name of that com‐
721 mand is found, then it is read and executed in the cur‐
722 rent environment. Unlike PATH, the current directory
723 must be represented explicitly by . rather than by adja‐
724 cent : characters or a beginning or ending :.
725 HISTCMD
726 Number of the current command in the history file.
727 HISTEDIT
728 Name for the default editor name for the hist command.
729 HISTFILE
730 If this variable is set when the shell is invoked, then
731 the value is the pathname of the file that will be used
732 to store the command history (see Command Re-entry be‐
733 low).
734 HISTSIZE
735 If this variable is set when the shell is invoked, then
736 the number of previously entered commands that are acces‐
737 sible by this shell will be greater than or equal to this
738 number. The default is 512.
739 HOME The default argument (home directory) for the cd command.
740 IFS Internal field separators, normally space, tab, and new-
741 line that are used to separate the results of command
742 substitution or parameter expansion and to separate
743 fields with the built-in command read. The first charac‐
744 ter of the IFS variable is used to separate arguments for
745 the "$*" substitution (see Quoting below). Each single
746 occurrence of an IFS character in the string to be split,
747 that is not in the isspace character class, and any adja‐
748 cent characters in IFS that are in the isspace character
749 class, delimit a field. One or more characters in IFS
750 that belong to the isspace character class, delimit a
751 field. In addition, if the same isspace character ap‐
752 pears consecutively inside IFS, this character is treated
753 as if it were not in the isspace class, so that if IFS
754 consists of two tab characters, then two adjacent tab
755 characters delimit a null field.
756 JOBMAX This variable defines the maximum number running back‐
757 ground jobs that can run at a time. When this limit is
758 reached, the shell will wait for a job to complete before
759 staring a new job.
760 LANG This variable determines the locale category for any cat‐
761 egory not specifically selected with a variable starting
762 with LC_ or LANG.
763 LC_ALL This variable overrides the value of the LANG variable
764 and any other LC_ variable.
765 LC_COLLATE
766 This variable determines the locale category for charac‐
767 ter collation information.
768 LC_CTYPE
769 This variable determines the locale category for charac‐
770 ter handling functions. It determines the character
771 classes for pattern matching (see File Name Generation
772 below).
773 LC_NUMERIC
774 This variable determines the locale category for the dec‐
775 imal point character.
776 LINES If this variable is set, the value is used to determine
777 the column length for printing select lists. Select
778 lists will print vertically until about two-thirds of
779 LINES lines are filled.
780 MAIL If this variable is set to the name of a mail file and
781 the MAILPATH variable is not set, then the shell informs
782 the user of arrival of mail in the specified file.
783 MAILCHECK
784 This variable specifies how often (in seconds) the shell
785 will check for changes in the modification time of any of
786 the files specified by the MAILPATH or MAIL variables.
787 The default value is 600 seconds. When the time has
788 elapsed the shell will check before issuing the next
789 prompt.
790 MAILPATH
791 A colon ( : ) separated list of file names. If this
792 variable is set, then the shell informs the user of any
793 modifications to the specified files that have occurred
794 within the last MAILCHECK seconds. Each file name can be
795 followed by a ? and a message that will be printed. The
796 message will undergo parameter expansion, command substi‐
797 tution, and arithmetic substitution with the variable $_
798 defined as the name of the file that has changed. The
799 default message is you have mail in $_.
800 PATH The search path for commands (see Execution below). The
801 user may not change PATH if executing under rksh (except
802 in .profile).
803 PS1 Every time a new command line is started on an interac‐
804 tive shell, the value of this variable is expanded to re‐
805 solve backslash escaping, parameter expansion, command
806 substitution, and arithmetic substitution. The result
807 defines the primary prompt string for that command line.
808 The default is ``$ ''. The character ! in the primary
809 prompt string is replaced by the command number (see Com‐
810 mand Re-entry below). Two successive occurrences of !
811 will produce a single ! when the prompt string is
812 printed. Note that any terminal escape sequences used in
813 the PS1 prompt thus need every instance of ! in them to
814 be changed to !!.
815 PS2 Secondary prompt string, by default ``> ''.
816 PS3 Selection prompt string used within a select loop, by de‐
817 fault ``#? ''.
818 PS4 The value of this variable is expanded for parameter
819 evaluation, command substitution, and arithmetic substi‐
820 tution and precedes each line of an execution trace. By
821 default, PS4 is ``+ ''. In addition when PS4 is unset,
822 the execution trace prompt is also ``+ ''.
823 SHELL The pathname of the shell is kept in the environment. At
824 invocation, if the basename of this variable is rsh,
825 rksh, or krsh, then the shell becomes restricted.
826 TIMEFORMAT
827 The value of this parameter is used as a format string
828 specifying how the timing information for pipelines pre‐
829 fixed with the time reserved word should be displayed.
830 The % character introduces a format sequence that is ex‐
831 panded to a time value or other information. The format
832 sequences and their meanings are as follows.
833 %% A literal %.
834 %[p][l]R The elapsed time in seconds.
835 %[p][l]U The number of CPU seconds spent in user mode.
836 %[p][l]S The number of CPU seconds spent in system mode.
837 %P The CPU percentage, computed as (U + S) / R.
838 The brackets denote optional portions. The optional p is
840 a digit specifying the precision, the number of frac‐
841 tional digits after a decimal point. A value of 0 causes
842 no decimal point or fraction to be output. At most three
843 places after the decimal point can be displayed; values
844 of p greater than 3 are treated as 3. If p is not speci‐
845 fied, the value 3 is used.
846 The optional l specifies a longer format, including hours
848 if greater than zero, minutes, and seconds of the form
849 HHhMMmSS.FFs. The value of p determines whether or not
850 the fraction is included.
851 All other characters are output without change and a
853 trailing newline is added. If unset, the default value,
854 $'\nreal\t%2lR\nuser\t%2lU\nsys\t%2lS', is used. If the
855 value is null, no timing information is displayed.
856 TMOUT Terminal read timeout. If set to a value greater than
858 zero, the read built-in command and the select compound
859 command time out after TMOUT seconds when input is from a
860 terminal. An interactive shell will issue a warning and
861 allow for an extra 60 second timeout grace period before
862 terminating if a line is not entered within the pre‐
863 scribed number of seconds while reading from a terminal.
864 (Note that the shell can be compiled with a maximum bound
865 for this value which cannot be exceeded.)
866 VISUAL If the value of this variable matches the pattern
868 *[Vv][Ii]*, then the vi option (see Special Command set
869 below) is turned on. If the value matches the pattern
870 *gmacs* , the gmacs option is turned on. If the value
871 matches the pattern *macs*, then the emacs option will be
872 turned on. The value of VISUAL overrides the value of
873 EDITOR.
874 The shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK,
876 FCEDIT, TMOUT and IFS, while HOME, SHELL, ENV, and MAIL are not set at
877 all by the shell (although HOME is set by login(1)). On some systems
878 MAIL and SHELL are also set by login(1).
879 Field Splitting.
881 After parameter expansion and command substitution, the results of sub‐
882 stitutions are scanned for the field separator characters (those found
883 in IFS) and split into distinct fields where such characters are found.
884 Explicit null fields ("" or ′′) are retained. Implicit null fields
885 (those resulting from parameters that have no values or command substi‐
886 tutions with no output) are removed.
887 Brace Expansion.
889 If the braceexpand (-B) option is set then each of the fields resulting
890 from IFS are checked to see if they contain one or more of the brace
891 patterns {*,*}, {l1..l2} , {n1..n2} , {n1..n2% fmt} , {n1..n2 ..n3} ,
892 or {n1..n2 ..n3%fmt} , where * represents any character, l1,l2 are let‐
893 ters and n1,n2,n3 are signed numbers and fmt is a format specified as
894 used by printf. In each case, fields are created by prepending the
895 characters before the { and appending the characters after the } to
896 each of the strings generated by the characters between the { and }.
897 The resulting fields are checked to see if they have any brace pat‐
898 terns.
899 In the first form, a field is created for each string between { and ,,
901 between , and ,, and between , and }. The string represented by * can
902 contain embedded matching { and } without quoting. Otherwise, each {
903 and } with * must be quoted.
904 In the seconds form, l1 and l2 must both be either upper case or both
906 be lower case characters in the C locale. In this case a field is cre‐
907 ated for each character from l1 thru l2.
908 In the remaining forms, a field is created for each number starting at
910 n1 and continuing until it reaches n2 incrementing n1 by n3. The cases
911 where n3 is not specified behave as if n3 where 1 if n1<=n2 and -1 oth‐
912 erwise. If forms which specify %fmt any format flags, widths and pre‐
913 cisions can be specified and fmt can end in any of the specifiers
914 cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to the 8
915 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx, z04bx and z04cx.
916 File Name Generation.
918 Following splitting, each field is scanned for the characters *, ?, (,
919 and [ unless the -f option has been set. If one of these characters
920 appears, then the word is regarded as a pattern. Each file name compo‐
921 nent that contains any pattern character is replaced with a lexico‐
922 graphically sorted set of names that matches the pattern from that di‐
923 rectory. If no file name is found that matches the pattern, then that
924 component of the filename is left unchanged unless the pattern is pre‐
925 fixed with ∼(N) in which case it is removed as described below. The
926 special traversal names . and .. are never matched. If FIGNORE is
927 set, then each file name component that matches the pattern defined by
928 the value of FIGNORE is ignored when generating the matching filenames.
929 If FIGNORE is not set, the character . at the start of each file name
930 component will be ignored unless the first character of the pattern
931 corresponding to this component is the character . itself. Note, that
932 for other uses of pattern matching the / and . are not treated spe‐
933 cially.
934 * Matches any string, including the null string. When used
936 for filename expansion, if the globstar option is on, an
937 isolated pattern of two adjacent *'s will match all files
938 and zero or more directories and subdirectories. If fol‐
939 lowed by a / then only directories and subdirectories
940 will match.
941 ? Matches any single character.
942 [...] Matches any one of the enclosed characters. A pair of
943 characters separated by - matches any character lexically
944 between the pair, inclusive. If the first character fol‐
945 lowing the opening [ is a ! or ^ then any character not
946 enclosed is matched. A - can be included in the charac‐
947 ter set by putting it as the first or last character.
948 Within [ and ], character classes can be specified with
949 the syntax [:class:] where class is one of the following
950 classes defined in the ANSI-C standard: (Note that word
951 is equivalent to alnum plus the character _.)
952 alnum alpha blank cntrl digit graph lower print punct
953 space upper word xdigit
954 Within [ and ], an equivalence class can be specified
955 with the syntax [=c=] which matches all characters with
956 the same primary collation weight (as defined by the cur‐
957 rent locale) as the character c. Within [ and ], [.sym‐
958 bol.] matches the collating symbol symbol.
959 A pattern-list is a list of one or more patterns separated from each
960 other with a & or |. A & signifies that all patterns must be matched
961 whereas | requires that only one pattern be matched. Composite pat‐
962 terns can be formed with one or more of the following sub-patterns:
963 ?(pattern-list)
964 Optionally matches any one of the given patterns.
965 *(pattern-list)
966 Matches zero or more occurrences of the given patterns.
967 +(pattern-list)
968 Matches one or more occurrences of the given patterns.
969 {n}(pattern-list)
970 Matches n occurrences of the given patterns.
971 {m,n}(pattern-list)
972 Matches from m to n occurrences of the given patterns.
973 If m is omitted, 0 will be used. If n is omitted at
974 least m occurrences will be matched.
975 @(pattern-list)
976 Matches exactly one of the given patterns.
977 !(pattern-list)
978 Matches anything except one of the given patterns.
979 By default, each pattern, or sub-pattern will match the longest string
980 possible consistent with generating the longest overall match. If more
981 than one match is possible, the one starting closest to the beginning
982 of the string will be chosen. However, for each of the above compound
983 patterns a - can be inserted in front of the ( to cause the shortest
984 match to the specified pattern-list to be used.
985 When pattern-list is contained within parentheses, the backslash char‐
987 acter \ is treated specially even when inside a character class. All
988 ANSI-C character escapes are recognized and match the specified charac‐
989 ter. In addition the following escape sequences are recognized:
990 \d Matches any character in the digit class.
991 \D Matches any character not in the digit class.
992 \s Matches any character in the space class.
993 \S Matches any character not in the space class.
994 \w Matches any character in the word class.
995 \W Matches any character not in the word class.
996 A pattern of the form %(pattern-pair(s)) is a sub-pattern that can be
998 used to match nested character expressions. Each pattern-pair is a two
999 character sequence which cannot contain & or |. The first pattern-pair
1000 specifies the starting and ending characters for the match. Each sub‐
1001 sequent pattern-pair represents the beginning and ending characters of
1002 a nested group that will be skipped over when counting starting and
1003 ending character matches. The behavior is unspecified when the first
1004 character of a pattern-pair is alphanumeric except for the following:
1005 D Causes the ending character to terminate the search for
1006 this pattern without finding a match.
1007 E Causes the ending character to be interpreted as an es‐
1008 cape character.
1009 L Causes the ending character to be interpreted as a quote
1010 character causing all characters to be ignored when look‐
1011 ing for a match.
1012 Q Causes the ending character to be interpreted as a quote
1013 character causing all characters other than any escape
1014 character to be ignored when looking for a match.
1015 Thus, %({}Q"E\), matches characters starting at { until the matching }
1016 is found not counting any { or } that is inside a double quoted string
1017 or preceded by the escape character \. Without the {} this pattern
1018 matches any C language string.
1019 Each sub-pattern in a composite pattern is numbered, starting at 1, by
1021 the location of the ( within the pattern. The sequence \n, where n is
1022 a single digit and \n comes after the n-th. sub-pattern, matches the
1023 same string as the sub-pattern itself.
1024 Finally a pattern can contain sub-patterns of the form ∼(options:pat‐
1026 tern-list), where either options or :pattern-list can be omitted. Un‐
1027 like the other compound patterns, these sub-patterns are not counted in
1028 the numbered sub-patterns. :pattern-list must be omitted for options
1029 F, G, N , and V below. If options is present, it can consist of one or
1030 more of the following:
1031 + Enable the following options. This is the default.
1032 - Disable the following options.
1033 E The remainder of the pattern uses extended regular ex‐
1034 pression syntax like the egrep(1) command.
1035 F The remainder of the pattern uses fgrep(1) expression
1036 syntax.
1037 G The remainder of the pattern uses basic regular expres‐
1038 sion syntax like the grep(1) command.
1039 K The remainder of the pattern uses shell pattern syntax.
1040 This is the default.
1041 N This is ignored. However, when it is the first letter
1042 and is used with file name generation, and no matches oc‐
1043 cur, the file pattern expands to the empty string.
1044 X The remainder of the pattern uses augmented regular ex‐
1045 pression syntax like the xgrep(1) command.
1046 P The remainder of the pattern uses perl(1) regular expres‐
1047 sion syntax. Not all perl regular expression syntax is
1048 currently implemented.
1049 V The remainder of the pattern uses System V regular ex‐
1050 pression syntax.
1051 i Always treat the match as case-insensitive, regardless of
1052 the globcasedetect shell option.
1053 g File the longest match (greedy). This is the default.
1054 l Left anchor the pattern. This is the default for K style
1055 patterns.
1056 r Right anchor the pattern. This is the default for K
1057 style patterns.
1058 If both options and :pattern-list are specified, then the options apply
1059 only to pattern-list. Otherwise, these options remain in effect until
1060 they are disabled by a subsequent ∼(...) or at the end of the sub-pat‐
1061 tern containing ∼(...).
1062 Quoting.
1064 Each of the metacharacters listed earlier (see Definitions above) has a
1065 special meaning to the shell and causes termination of a word unless
1066 quoted. A character may be quoted (i.e., made to stand for itself) by
1067 preceding it with a \. The pair \new-line is removed. All characters
1068 enclosed between a pair of single quote marks (′′) that is not preceded
1069 by a $ are quoted. A single quote cannot appear within the single
1070 quotes. A single quoted string preceded by an unquoted $ is processed
1071 as an ANSI-C string except for the following:
1072 \0 Causes the remainder of the string to be ignored.
1073 \E Equivalent to the escape character (ascii 033),
1074 \e Equivalent to the escape character (ascii 033),
1075 \cx Expands to the character control-x.
1076 \C[.name.]
1077 Expands to the collating element name.
1078 Inside double quote marks (""), parameter and command substitution oc‐
1080 cur and \ quotes the characters \, `, ", and $. A $ in front of a dou‐
1081 ble quoted string will be ignored in the "C" or "POSIX" locale, and may
1082 cause the string to be replaced by a locale specific string otherwise.
1083 The meaning of $* and $@ is identical when not quoted or when used as a
1084 variable assignment value or as a file name. However, when used as a
1085 command argument, "$*" is equivalent to "$1d$2d...", where d is the
1086 first character of the IFS variable, whereas "$@" is equivalent to "$1"
1087 "$2" .... Inside grave quote marks (``), \ quotes the characters \, `,
1088 and $. If the grave quotes occur within double quotes, then \ also
1089 quotes the character ".
1090 The special meaning of reserved words or aliases can be removed by
1092 quoting any character of the reserved word. The recognition of func‐
1093 tion names or built-in command names listed below cannot be altered by
1094 quoting them.
1095 Arithmetic Evaluation.
1097 The shell performs arithmetic evaluation for arithmetic substitution,
1098 to evaluate an arithmetic command, to evaluate an indexed array sub‐
1099 script, and to evaluate arguments to the built-in commands shift and
1100 let. Evaluations are performed using double precision floating point
1101 arithmetic or long double precision floating point for systems that
1102 provide this data type. Floating point constants follow the ANSI-C
1103 programming language floating point conventions. The floating point
1104 constants Nan and Inf can be used to represent "not a number" and in‐
1105 finity respectively. Integer constants follow the ANSI-C programming
1106 language integer constant conventions although only single byte charac‐
1107 ter constants are recognized and character casts are not recognized.
1108 In addition constants can be of the form [base#]n where base is a deci‐
1109 mal number between two and sixty-four representing the arithmetic base
1110 and n is a number in that base. The digits above 9 are represented by
1111 the lower case letters, the upper case letters, @, and _ respectively.
1112 For bases less than or equal to 36, upper and lower case characters can
1113 be used interchangeably.
1114 An arithmetic expression uses the same syntax, precedence, and associa‐
1116 tivity of expression as the C language. All the C language operators
1117 that apply to floating point quantities can be used. In addition, the
1118 operator ** can be used for exponentiation. It has higher precedence
1119 than multiplication and is left associative. In addition, when the
1120 value of an arithmetic variable or sub-expression can be represented as
1121 a long integer, all C language integer arithmetic operations can be
1122 performed. Variables can be referenced by name within an arithmetic
1123 expression without using the parameter expansion syntax. When a vari‐
1124 able is referenced, its value is evaluated as an arithmetic expression.
1125 Any of the following math library functions that are in the C math li‐
1127 brary can be used within an arithmetic expression:
1128 abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh
1130 erf erfc exp exp10 exp2 expm1 fabs fdim finite float floor fma fmax
1131 fmin fmod fpclass fpclassify hypot ilogb int isfinite isgreater is‐
1132 greaterequal isinf isinfinite isless islessequal islessgreater isnan
1133 isnormal issubnormal isunordered iszero j0 j1 jn ldexp lgamma log log10
1134 log1p log2 logb nearbyint nextafter nexttoward pow remainder rint round
1135 scalb scalbn signbit sin sinh sqrt tan tanh tgamma trunc y0 y1 yn
1136 In addition, arithmetic functions can be defined as shell functions
1138 with a variant of the function name syntax,
1139 function .sh.math.name ident ... { list ;}
1141 where name is the function name used in the arithmetic expres‐
1142 sion and each identifier, ident is a name reference to the long
1143 double precision floating point argument. The value of
1144 .sh.value when the function returns is the value of this func‐
1145 tion. User defined functions can take up to 3 arguments and
1146 override C math library functions.
1147 An internal representation of a variable as a double precision floating
1149 point can be specified with the -E [n], -F [n], or -X [n] option of the
1150 typeset special built-in command. The -E option causes the expansion
1151 of the value to be represented using scientific notation when it is ex‐
1152 panded. The optional option argument n defines the number of signifi‐
1153 cant figures. The -F option causes the expansion to be represented as
1154 a floating decimal number when it is expanded. The -X option causes
1155 the expansion to be represented using the %a format defined by ISO
1156 C-99. The optional option argument n defines the number of places af‐
1157 ter the decimal (or radix) point in this case.
1158 An internal integer representation of a variable can be specified with
1160 the -i [n] option of the typeset special built-in command. The op‐
1161 tional option argument n specifies an arithmetic base to be used when
1162 expanding the variable. If you do not specify an arithmetic base, base
1163 10 will be used.
1164 Arithmetic evaluation is performed on the value of each assignment to a
1166 variable with the -E, -F, -X, or -i attribute. Assigning a floating
1167 point number to a variable whose type is an integer causes the frac‐
1168 tional part to be truncated.
1169 Prompting.
1171 When used interactively, the shell prompts with the value of PS1 after
1172 expanding it for parameter expansion, command substitution, and arith‐
1173 metic substitution, before reading a command. In addition, each single
1174 ! in the prompt is replaced by the command number. A !! is required
1175 to place ! in the prompt. If at any time a new-line is typed and fur‐
1176 ther input is needed to complete a command, then the secondary prompt
1177 (i.e., the value of PS2) is issued.
1178 Conditional Expressions.
1180 A conditional expression is used with the [[ compound command to test
1181 attributes of files and to compare strings. Field splitting and file
1182 name generation are not performed on the words between [[ and ]]. Each
1183 expression can be constructed from one or more of the following unary
1184 or binary expressions:
1185 string True, if string is not null.
1186 -a file
1187 Same as -e below. This is obsolete.
1188 -b file
1189 True, if file exists and is a block special file.
1190 -c file
1191 True, if file exists and is a character special file.
1192 -d file
1193 True, if file exists and is a directory.
1194 -e file
1195 True, if file exists.
1196 -f file
1197 True, if file exists and is an ordinary file.
1198 -g file
1199 True, if file exists and it has its setgid bit set.
1200 -k file
1201 True, if file exists and it has its sticky bit set.
1202 -n string
1203 True, if length of string is non-zero.
1204 -o ?option
1205 True, if option named option is a valid option name.
1206 -o option
1207 True, if option named option is on.
1208 -p file
1209 True, if file exists and is a fifo special file or a pipe.
1210 -r file
1211 True, if file exists and is readable by current process.
1212 -s file
1213 True, if file exists and has size greater than zero.
1214 -t fildes
1215 True, if file descriptor number fildes is open and associated
1216 with a terminal device.
1217 -u file
1218 True, if file exists and it has its setuid bit set.
1219 -v name
1220 True, if variable name is a valid variable name and is set.
1221 -w file
1222 True, if file exists and is writable by current process.
1223 -x file
1224 True, if file exists and is executable by current process. If
1225 file exists and is a directory, then true if the current process
1226 has permission to search in the directory.
1227 -z string
1228 True, if length of string is zero.
1229 -L file
1230 True, if file exists and is a symbolic link.
1231 -h file
1232 True, if file exists and is a symbolic link.
1233 -N file
1234 True, if file exists and the modification time is greater than
1235 the last access time.
1236 -O file
1237 True, if file exists and is owned by the effective user id of
1238 this process.
1239 -G file
1240 True, if file exists and its group matches the effective group
1241 id of this process.
1242 -R name
1243 True if variable name is a name reference.
1244 -S file
1245 True, if file exists and is a socket.
1246 file1 -nt file2
1247 True, if file1 exists and file2 does not, or file1 is newer than
1248 file2.
1249 file1 -ot file2
1250 True, if file2 exists and file1 does not, or file1 is older than
1251 file2.
1252 file1 -ef file2
1253 True, if file1 and file2 exist and refer to the same file.
1254 string == pattern
1255 True, if string matches pattern. Any part of pattern can be
1256 quoted to cause it to be matched as a string. With a successful
1257 match to a pattern, the .sh.match array variable will contain
1258 the match and sub-pattern matches.
1259 string = pattern
1260 Same as == above, but is obsolete.
1261 string != pattern
1262 True, if string does not match pattern. When the string matches
1263 the pattern the .sh.match array variable will contain the match
1264 and sub-pattern matches.
1265 string =∼ ere
1266 True if string matches the pattern ∼(E)ere where ere is an ex‐
1267 tended regular expression.
1268 string1 < string2
1269 True, if string1 comes before string2 based on ASCII value of
1270 their characters.
1271 string1 > string2
1272 True, if string1 comes after string2 based on ASCII value of
1273 their characters.
1274 The following obsolete arithmetic comparisons are also permitted:
1275 exp1 -eq exp2
1276 True, if exp1 is equal to exp2.
1277 exp1 -ne exp2
1278 True, if exp1 is not equal to exp2.
1279 exp1 -lt exp2
1280 True, if exp1 is less than exp2.
1281 exp1 -gt exp2
1282 True, if exp1 is greater than exp2.
1283 exp1 -le exp2
1284 True, if exp1 is less than or equal to exp2.
1285 exp1 -ge exp2
1286 True, if exp1 is greater than or equal to exp2.
1287 In each of the above expressions, if file is of the form /dev/fd/n,
1289 where n is an integer, then the test is applied to the open file whose
1290 descriptor number is n.
1291 A compound expression can be constructed from these primitives by using
1293 any of the following, listed in decreasing order of precedence.
1294 (expression)
1295 True, if expression is true. Used to group expressions.
1296 ! expression
1297 True if expression is false.
1298 expression1 && expression2
1299 True, if expression1 and expression2 are both true.
1300 expression1 || expression2
1301 True, if either expression1 or expression2 is true.
1302 Input/Output.
1304 Before a command is executed, its input and output may be redirected
1305 using a special notation interpreted by the shell. The following may
1306 appear anywhere in a simple-command or may precede or follow a command
1307 and are not passed on to the invoked command. Command substitution,
1308 parameter expansion, and arithmetic substitution occur before word or
1309 digit is used except as noted below. File name generation occurs only
1310 if the shell is interactive and the pattern matches a single file.
1311 Field splitting is not performed.
1312 In each of the following redirections, if file is of the form
1314 /dev/sctp/host/port, /dev/tcp/host/port, or /dev/udp/host/port, where
1315 host is a hostname or host address, and port is a service given by name
1316 or an integer port number, then the redirection attempts to make a tcp,
1317 sctp or udp connection to the corresponding socket.
1318 No intervening space is allowed between the characters of redirection
1320 operators.
1321 <word Use file word as standard input (file descriptor 0).
1323 >word Use file word as standard output (file descriptor 1). If
1325 the file does not exist then it is created. If the file
1326 exists, and the noclobber option is on, this causes an
1327 error; otherwise, it is truncated to zero length.
1328 >|word Same as >, except that it overrides the noclobber option.
1330 >;word Write output to a temporary file. If the command com‐
1332 pletes successfully rename it to word, otherwise, delete
1333 the temporary file. >;word cannot be used with the exec
1334 and redirect built-ins.
1335 >>word Use file word as standard output. If the file exists,
1337 then output is appended to it (by first seeking to the
1338 end-of-file); otherwise, the file is created.
1339 <>word Open file word for reading and writing as standard out‐
1341 put. If the posix option is active, it defaults to stan‐
1342 dard input instead.
1343 <>;word The same as <>word except that if the command completes
1345 successfully, word is truncated to the offset at command
1346 completion. <>;word cannot be used with the exec and re‐
1347 direct built-ins.
1348 <<[-]word The shell input is read up to a line that is the same as
1350 word after any quoting has been removed, or to an end-of-
1351 file. No parameter substitution, command substitution,
1352 arithmetic substitution or file name generation is per‐
1353 formed on word. The resulting document, called a here-
1354 document, becomes the standard input. If any character
1355 of word is quoted, then no interpretation is placed upon
1356 the characters of the document; otherwise, parameter ex‐
1357 pansion, command substitution, and arithmetic substitu‐
1358 tion occur, \new-line is ignored, and \ must be used to
1359 quote the characters \, $, `. If - is appended to <<,
1360 then all leading tabs are stripped from word and from the
1361 document. If # is appended to <<, then leading spaces
1362 and tabs will be stripped off the first line of the docu‐
1363 ment and up to an equivalent indentation will be stripped
1364 from the remaining lines and from word. A tab stop is
1365 assumed to occur at every 8 columns for the purposes of
1366 determining the indentation.
1367 <<<word A short form of here document in which word becomes the
1369 contents of the here-document after any parameter expan‐
1370 sion, command substitution, and arithmetic substitution
1371 occur.
1372 <&digit The standard input is duplicated from file descriptor
1374 digit (see dup(2)).
1375 >&digit The standard output is duplicated from file descriptor
1377 digit.
1378 <&digit- The file descriptor given by digit is moved to standard
1380 input.
1381 >&digit- The file descriptor given by digit is moved to standard
1383 output.
1384 <&- The standard input is closed.
1386 >&- The standard output is closed.
1388 <&p The input from the co-process is moved to standard input.
1390 >&p The output to the co-process is moved to standard output.
1392 <#((expr)) Evaluate arithmetic expression expr and position file de‐
1394 scriptor 0 to the resulting value bytes from the start of
1395 the file. The variables CUR and EOF evaluate to the cur‐
1396 rent offset and end-of-file offset respectively when
1397 evaluating expr.
1398 >#((offset)) The same as <# except applies to file descriptor 1.
1400 <#pattern Seeks forward to the beginning of the next line contain‐
1402 ing pattern.
1403 <##pattern The same as <# except that the portion of the file that
1405 is skipped is copied to standard output.
1406 If one of the above is preceded by a digit, with no intervening space,
1408 then the file descriptor number referred to is that specified by the
1409 digit (instead of the default 0 or 1). If one of the above, other than
1410 >&- and the ># and <# forms, is preceded by {varname} with no interven‐
1411 ing space, then a file descriptor number > 9 will be selected by the
1412 shell and stored in the variable varname, so it can be read from or
1413 written to with redirections like <& $varname or >& $varname. If >&-
1414 or the any of the ># and <# forms is preceded by {varname} the value of
1415 varname defines the file descriptor to close or position. For example:
1416 ... 2>&1
1418 means file descriptor 2 is to be opened for writing as a duplicate of
1420 file descriptor 1 and
1421 exec {n}<file
1423 means open file named file for reading and store the file descriptor
1425 number in variable n.
1426 A special shorthand redirection operator &>word is available; it is
1428 equivalent to >word 2>&1. It cannot be preceded by any digit or vari‐
1429 able name. This shorthand is disabled if the posix shell option is ac‐
1430 tive.
1431 The order in which redirections are specified is significant. The
1433 shell evaluates each redirection in terms of the (file descriptor,
1434 file) association at the time of evaluation. For example:
1435 ... 1>fname 2>&1
1437 first associates file descriptor 1 with file fname. It then associates
1439 file descriptor 2 with the file associated with file descriptor 1 (i.e.
1440 fname). If the order of redirections were reversed, file descriptor 2
1441 would be associated with the terminal (assuming file descriptor 1 had
1442 been) and then file descriptor 1 would be associated with file fname.
1443 If a command is followed by & and job control is not active, then the
1445 default standard input for the command is the empty file /dev/null.
1446 Otherwise, the environment for the execution of a command contains the
1447 file descriptors of the invoking shell as modified by input/output
1448 specifications.
1449 Environment.
1451 The environment (see environ(7)) is a list of name-value pairs that is
1452 passed to an executed program in the same way as a normal argument
1453 list. The names must be identifiers and the values are character
1454 strings. The shell interacts with the environment in several ways. On
1455 invocation, the shell scans the environment and creates a variable for
1456 each name found, giving it the corresponding value and attributes and
1457 marking it export. Executed commands inherit the environment. If the
1458 user modifies the values of these variables or creates new ones, using
1459 the export or typeset -x commands, they become part of the environment.
1460 The environment seen by any executed command is thus composed of any
1461 name-value pairs originally inherited by the shell, whose values may be
1462 modified by the current shell, plus any additions which must be noted
1463 in export or typeset -x commands.
1464 The environment for any simple-command or function may be augmented by
1466 prefixing it with one or more variable assignments. A variable assign‐
1467 ment argument is a word of the form identifier=value. Thus:
1468 TERM=450 cmd args and
1470 (export TERM; TERM=450; cmd args)
1471 are equivalent (as far as the above execution of cmd is concerned ex‐
1473 cept for special built-in commands listed below - those that are marked
1474 with †).
1475 If the obsolete -k option is set, all variable assignment arguments are
1477 placed in the environment, even if they occur after the command name.
1478 The following first prints a=b c and then c:
1479 echo a=b c
1481 set -k
1482 echo a=b c
1483 This feature is intended for use with scripts written for early ver‐
1484 sions of the shell and its use in new scripts is strongly discouraged.
1485 It is likely to disappear someday.
1486 Functions.
1488 For historical reasons, there are two ways to define functions, the
1489 name() syntax and the function name syntax, described in the Commands
1490 section above. Shell functions are read in and stored internally.
1491 Alias names are resolved when the function is read. Functions are exe‐
1492 cuted like commands with the arguments passed as positional parameters.
1493 (See Execution below.)
1494 Functions defined by the function name syntax and called by name exe‐
1496 cute in the same process as the caller and share all files and present
1497 working directory with the caller. Traps caught by the caller are re‐
1498 set to their default action inside the function. A trap condition that
1499 is not caught or ignored by the function causes the function to termi‐
1500 nate and the condition to be passed on to the caller. A trap on EXIT
1501 set inside a function is executed in the environment of the caller af‐
1502 ter the function completes. Ordinarily, variables are shared between
1503 the calling program and the function. However, the typeset special
1504 built-in command used within a function defines local variables whose
1505 scope includes the current function. They can be passed to functions
1506 that they call in the variable assignment list that precedes the call
1507 or as arguments passed as name references. Errors within functions re‐
1508 turn control to the caller.
1509 Functions defined with the name() syntax and functions defined with the
1511 function name syntax that are invoked with the . special built-in are
1512 executed in the caller's environment and share all variables and traps
1513 with the caller. Errors within these function executions cause the
1514 script that contains them to abort.
1515 The special built-in command return is used to return from function
1517 calls.
1518 Function names can be listed with the -f or +f option of the typeset
1520 special built-in command. The text of functions, when available, will
1521 also be listed with -f. Functions can be undefined with the -f option
1522 of the unset special built-in command.
1523 Ordinarily, functions are unset when the shell executes a shell script.
1525 Functions that need to be defined across separate invocations of the
1526 shell should be placed in a directory and the FPATH variable should
1527 contain the name of this directory. They may also be specified in the
1528 ENV file.
1529 Discipline Functions.
1531 Each variable can have zero or more discipline functions associated
1532 with it. The shell initially understands the discipline names get,
1533 set, append, and unset but can be added when defining new types. On
1534 most systems others can be added at run time via the C programming in‐
1535 terface extension provided by the builtin built-in utility. If the get
1536 discipline is defined for a variable, it is invoked whenever the given
1537 variable is referenced. If the variable .sh.value is assigned a value
1538 inside the discipline function, the referenced variable will evaluate
1539 to this value instead. If the set discipline is defined for a vari‐
1540 able, it is invoked whenever the given variable is assigned a value.
1541 If the append discipline is defined for a variable, it is invoked when‐
1542 ever a value is appended to the given variable. The variable .sh.value
1543 is given the value of the variable before invoking the discipline, and
1544 the variable will be assigned the value of .sh.value after the disci‐
1545 pline completes. If .sh.value is unset inside the discipline, then
1546 that value is unchanged. If the unset discipline is defined for a
1547 variable, it is invoked whenever the given variable is unset. The
1548 variable will not be unset unless it is unset explicitly from within
1549 this discipline function.
1550 The variable .sh.name contains the name of the variable for which the
1552 discipline function is called, .sh.subscript is the subscript of the
1553 variable, and .sh.value will contain the value being assigned inside
1554 the set discipline function. The variable _ is a reference to the
1555 variable including the subscript if any. For the set discipline,
1556 changing .sh.value will change the value that gets assigned. Finally,
1557 the expansion ${var.name}, when name is the name of a discipline, and
1558 there is no variable of this name, is equivalent to the command substi‐
1559 tution ${ var.name;}.
1560 Name Spaces.
1563 Commands and functions that are executed as part of the list of a name‐
1564 space command that modify variables or create new ones, create a new
1565 variable whose name is the name of the name space as given by identi‐
1566 fier preceded by .. When a variable whose name is name is referenced,
1567 it is first searched for using .identifier.name. Similarly, a function
1568 defined by a command in the namespace list is created using the name
1569 space name preceded by a ..
1570 When the list of a namespace command contains a namespace command, the
1572 names of variables and functions that are created consist of the vari‐
1573 able or function name preceded by the list of identifiers each preceded
1574 by ..
1575 Outside of a name space, a variable or function created inside a name
1577 space can be referenced by preceding it with the name space name.
1578 By default, variables staring with .sh are in the sh name space.
1580 Type Variables.
1583 Typed variables provide a way to create data structure and objects. A
1584 type can be defined either by a shared library, by the enum built-in
1585 command described below, or by using the new -T option of the typeset
1586 built-in command. With the -T option of typeset, the type name, speci‐
1587 fied as an option argument to -T, is set with a compound variable as‐
1588 signment that defines the type. Function definitions can appear inside
1589 the compound variable assignment and these become discipline functions
1590 for this type and can be invoked or redefined by each instance of the
1591 type. The function name create is treated specially. It is invoked
1592 for each instance of the type that is created but is not inherited and
1593 cannot be redefined for each instance.
1594 When a type is defined a special built-in command of that name is
1596 added. These built-ins are declaration commands and follow the same
1597 expansion rules as the built-in commands described below that are
1598 marked with a ‡ symbol. These commands can subsequently be used inside
1599 further type definitions. The man page for these commands can be gen‐
1600 erated by using the --man option or any of the other -- options de‐
1601 scribed with getopts. The -r, -a, -A, -h, and -S options of typeset
1602 are permitted with each of these new built-ins.
1603 An instance of a type is created by invoking the type name followed by
1605 one or more instance names. Each instance of the type is initialized
1606 with a copy of the sub-variables except for sub-variables that are de‐
1607 fined with the -S option. Variables defined with the -S are shared by
1608 all instances of the type. Each instance can change the value of any
1609 sub-variable and can also define new discipline functions of the same
1610 names as those defined by the type definition as well as any standard
1611 discipline names. No additional sub-variables can be defined for any
1612 instance.
1613 When defining a type, if the value of a sub-variable is not set and the
1615 -r attribute is specified, it causes the sub-variable to be a required
1616 sub-variable. Whenever an instance of a type is created, all required
1617 sub-variables must be specified. These sub-variables become readonly
1618 in each instance.
1619 When unset is invoked on a sub-variable within a type, and the -r at‐
1621 tribute has not been specified for this field, the value is reset to
1622 the default value associative with the type. Invoking unset on a type
1623 instance not contained within another type deletes all sub-variables
1624 and the variable itself.
1625 A type definition can be derived from another type definition by defin‐
1627 ing the first sub-variable name as _ and defining its type as the base
1628 type. Any remaining definitions will be additions and modifications
1629 that apply to the new type. If the new type name is the same as that
1630 of the base type, the type will be replaced and the original type will
1631 no longer be accessible.
1632 The typeset command with the -T and no option argument or operands will
1634 write all the type definitions to standard output in a form that can be
1635 read in to create all they types.
1636 Jobs.
1638 If the monitor option of the set command is turned on, an interactive
1639 shell associates a job with each pipeline. It keeps a table of current
1640 jobs, printed by the jobs command, and assigns them small integer num‐
1641 bers. When a job is started asynchronously with &, the shell prints a
1642 line which looks like:
1643 [1] 1234
1645 indicating that the job which was started asynchronously was job number
1647 1 and had one (top-level) process, whose process id was 1234.
1648 This paragraph and the next require features that are not in all ver‐
1650 sions of UNIX and may not apply. If you are running a job and wish to
1651 do something else you may hit the key ^Z (control-Z) which sends a STOP
1652 signal to the current job. The shell will then normally indicate that
1653 the job has been `Stopped', and print another prompt. You can then ma‐
1654 nipulate the state of this job, putting it in the background with the
1655 bg command, or run some other commands and then eventually bring the
1656 job back into the foreground with the foreground command fg. A ^Z
1657 takes effect immediately and is like an interrupt in that pending out‐
1658 put and unread input are discarded when it is typed.
1659 A job being run in the background will stop if it tries to read from
1661 the terminal. Background jobs are normally allowed to produce output,
1662 but this can be disabled by giving the command stty tostop. If you set
1663 this tty option, then background jobs will stop when they try to pro‐
1664 duce output like they do when they try to read input.
1665 A job pool is a collection of jobs started with list & associated with
1667 a name.
1668 There are several ways to refer to jobs in the shell. A job can be re‐
1670 ferred to by the process id of any process of the job or by one of the
1671 following:
1672 %number
1673 The job with the given number.
1674 pool All the jobs in the job pool named by pool.
1675 pool.number
1676 The job number number in the job pool named by pool.
1677 %string
1678 Any job whose command line begins with string.
1679 %?string
1680 Any job whose command line contains string.
1681 %% Current job.
1682 %+ Equivalent to %%.
1683 %- Previous job. In addition, unless noted otherwise, wherever a
1684 job can be specified, the name of a background job pool can be
1685 used to represent all the jobs in that pool.
1686 The shell learns immediately whenever a process changes state. It nor‐
1688 mally informs you whenever a job becomes blocked so that no further
1689 progress is possible, but only just before it prints a prompt. This is
1690 done so that it does not otherwise disturb your work. The notify op‐
1691 tion of the set command causes the shell to print these job change mes‐
1692 sages as soon as they occur.
1693 When the monitor option is on, each background job that completes trig‐
1695 gers any trap set for CHLD.
1696 When you try to leave the shell while jobs are running or stopped, you
1698 will be warned that `You have stopped(running) jobs.' You may use the
1699 jobs command to see what they are. If you immediately try to exit
1700 again, the shell will not warn you a second time, and the stopped jobs
1701 will be terminated. When a login shell receives a HUP signal, it sends
1702 a HUP signal to each job that has not been disowned with the disown
1703 built-in command described below.
1704 Signals.
1706 The INT and QUIT signals for an invoked command are ignored if the com‐
1707 mand is followed by & and the monitor option is not active. Otherwise,
1708 signals have the values inherited by the shell from its parent (but see
1709 also the trap built-in command below).
1710 Execution.
1712 Each time a command is read, the above substitutions are carried out.
1713 If the command name matches one of the Special Built-in Commands listed
1714 below, it is executed within the current shell process. Next, the com‐
1715 mand name is checked to see if it matches a user defined function. If
1716 it does, the positional parameters are saved and then reset to the ar‐
1717 guments of the function call. A function is also executed in the cur‐
1718 rent shell process. When the function completes or issues a return,
1719 the positional parameter list is restored. For functions defined with
1720 the function name syntax, any trap set on EXIT within the function is
1721 executed. The exit value of a function is the value of the last com‐
1722 mand executed. If a command name is not a special built-in command or
1723 a user defined function, but it is one of the built-in commands listed
1724 below, it is executed in the current shell process.
1725 The shell variables PATH followed by the variable FPATH defines the
1727 list of directories to search for the command name. Alternative direc‐
1728 tory names are separated by a colon (:). The default path is the value
1729 that was output by getconf PATH at the time ksh was compiled. The cur‐
1730 rent directory can be specified by two or more adjacent colons, or by a
1731 colon at the beginning or end of the path list. If the command name
1732 contains a /, then the search path is not used. Otherwise, each direc‐
1733 tory in the list of directories defined by PATH and FPATH is checked in
1734 order. If the directory being searched is contained in FPATH and con‐
1735 tains a file whose name matches the command being searched, then this
1736 file is loaded into the current shell environment as if it were the ar‐
1737 gument to the . command except that only preset aliases are expanded,
1738 and a function of the given name is executed as described above.
1739 If this directory is not in FPATH the shell first determines whether
1741 there is a built-in version of a command corresponding to a given path‐
1742 name and if so it is invoked in the current process. If no built-in is
1743 found, the shell checks for a file named .paths in this directory. If
1744 found and there is a line of the form FPATH=path where path names an
1745 existing directory then that directory is searched immediately after
1746 the current directory as if it were found in the FPATH variable. If
1747 path does not begin with /, it is checked for relative to the directory
1748 being searched.
1749 The .paths file is then checked for a line of the form PLUGIN_LIB=lib‐
1751 name [ : libname ] ... . Each library named by libname will be
1752 searched for as if it were an option argument to builtin -f, and if it
1753 contains a built-in of the specified name this will be executed instead
1754 of a command by this name. Any built-in loaded from a library found
1755 this way will be associated with the directory containing the .paths
1756 file so it will only execute if not found in an earlier directory.
1757 Finally, the directory will be checked for a file of the given name.
1759 If the file has execute permission but is not an a.out file, it is as‐
1760 sumed to be a file containing shell commands. A separate shell is
1761 spawned to read it. All non-exported variables are removed in this
1762 case. If the shell command file doesn't have read permission, or if
1763 the setuid and/or setgid bits are set on the file, then the shell exe‐
1764 cutes an agent whose job it is to set up the permissions and execute
1765 the shell with the shell command file passed down as an open file. If
1766 the .paths contains a line of the form name=value in the first or sec‐
1767 ond line, then the environment variable name is modified by prepending
1768 the directory specified by value to the directory list. If value is
1769 not an absolute directory, then it specifies a directory relative to
1770 the directory that the executable was found. If the environment vari‐
1771 able name does not already exist it will be added to the environment
1772 list for the specified command. A parenthesized command is executed in
1773 a subshell without removing non-exported variables.
1774 Command Re-entry.
1776 The text of the last HISTSIZE (default 512) commands entered from a
1777 terminal device is saved in a history file. The file $HOME/.sh_history
1778 is used if the HISTFILE variable is not set or if the file it names is
1779 not writable. A shell can access the commands of all interactive
1780 shells which use the same named HISTFILE. The built-in command hist is
1781 used to list or edit a portion of this file. The portion of the file
1782 to be edited or listed can be selected by number or by giving the first
1783 character or characters of the command. A single command or range of
1784 commands can be specified. If you do not specify an editor program as
1785 an argument to hist then the value of the variable HISTEDIT is used.
1786 If HISTEDIT is unset, the obsolete variable FCEDIT is used. If FCEDIT
1787 is not defined, then /bin/ed is used. The edited command(s) is printed
1788 and re-executed upon leaving the editor unless you quit without writ‐
1789 ing. The -s option (and in obsolete versions, the editor name -) is
1790 used to skip the editing phase and to re-execute the command. In this
1791 case a substitution parameter of the form old=new can be used to modify
1792 the command before execution. For example, with the preset alias r,
1793 which is aliased to ′hist -s′, typing `r bad=good c' will re-execute
1794 the most recent command which starts with the letter c, replacing the
1795 first occurrence of the string bad with the string good.
1796 In-line Editing Options.
1798 Normally, each command line entered from a terminal device is simply
1799 typed followed by a new-line (`RETURN' or `LINE FEED'). If either the
1800 emacs, gmacs, or vi option is active, the user can edit the command
1801 line. To be in either of these edit modes set the corresponding op‐
1802 tion. An editing option is automatically selected each time the VISUAL
1803 or EDITOR variable is assigned a value ending in either of these option
1804 names.
1805 The editing features require that the user's terminal accept `RETURN'
1807 as carriage return without line feed and that a space (` ') must over‐
1808 write the current character on the screen.
1809 Unless the multiline option is on, the editing modes implement a con‐
1811 cept where the user is looking through a window at the current line.
1812 The window width is the value of COLUMNS if it is defined, otherwise
1813 80. If the window width is too small to display the prompt and leave
1814 at least 8 columns to enter input, the prompt is truncated from the
1815 left. If the line is longer than the window width minus two, a mark is
1816 displayed at the end of the window to notify the user. As the cursor
1817 moves and reaches the window boundaries the window will be centered
1818 about the cursor. The mark is a > (<, *) if the line extends on the
1819 right (left, both) side(s) of the window.
1820 The search commands in each edit mode provide access to the history
1822 file. Only strings are matched, not patterns, although a leading ^ in
1823 the string restricts the match to begin at the first character in the
1824 line.
1825 Each of the edit modes has an operation to list the files or commands
1827 that match a partially entered word. When applied to the first word on
1828 the line, or the first word after a ;, |, &, or (, and the word does
1829 not begin with ∼ or contain a /, the list of aliases, functions, and
1830 executable commands defined by the PATH variable that could match the
1831 partial word is displayed. Otherwise, the list of files that match the
1832 given word is displayed. If the partially entered word does not con‐
1833 tain any file expansion characters, a * is appended before generating
1834 these lists. After displaying the generated list, the input line is
1835 redrawn. These operations are called command name listing and file
1836 name listing, respectively. There are additional operations, referred
1837 to as command name completion and file name completion, which compute
1838 the list of matching commands or files, but instead of printing the
1839 list, replace the current word with a complete or partial match. For
1840 file name completion, if the match is unique, a / is appended if the
1841 file is a directory and a space is appended if the file is not a direc‐
1842 tory. Otherwise, the longest common prefix for all the matching files
1843 replaces the word. For command name completion, only the portion of
1844 the file names after the last / are used to find the longest command
1845 prefix. If only a single name matches this prefix, then the word is
1846 replaced with the command name followed by a space. When using a tab
1847 for completion that does not yield a unique match, a subsequent tab
1848 will provide a numbered list of matching alternatives. A specific se‐
1849 lection can be made by entering the selection number followed by a tab.
1850 Key Bindings.
1852 The KEYBD trap can be used to intercept keys as they are typed and
1853 change the characters that are actually seen by the shell. This trap
1854 is executed after each character (or sequence of characters when the
1855 first character is ESC) is entered while reading from a terminal. The
1856 variable .sh.edchar contains the character or character sequence which
1857 generated the trap. Changing the value of .sh.edchar in the trap ac‐
1858 tion causes the shell to behave as if the new value were entered from
1859 the keyboard rather than the original value.
1860 The variable .sh.edcol is set to the input column number of the cursor
1862 at the time of the input. The variable .sh.edmode is set to ESC when
1863 in vi insert mode (see below) and is null otherwise. By prepending
1864 ${.sh.editmode} to a value assigned to .sh.edchar it will cause the
1865 shell to change to control mode if it is not already in this mode.
1866 This trap is not invoked for characters entered as arguments to editing
1868 directives, or while reading input for a character search.
1869 Emacs Editing Mode.
1871 This mode is entered by enabling either the emacs or gmacs option. The
1872 only difference between these two modes is the way they handle ^T. To
1873 edit, the user moves the cursor to the point needing correction and
1874 then inserts or deletes characters or words as needed. All the editing
1875 commands are control characters or escape sequences. The notation for
1876 control characters is caret (^) followed by the character. For exam‐
1877 ple, ^F is the notation for control F. This is entered by depressing
1878 `f' while holding down the `CTRL' (control) key. The `SHIFT' key is
1879 not depressed. (The notation ^? indicates the DEL (delete) key.)
1880 The notation for escape sequences is M- followed by a character. For
1882 example, M-f (pronounced Meta f) is entered by depressing ESC (ascii
1883 033) followed by `f'. (M-F would be the notation for ESC followed by
1884 `SHIFT' (capital) `F'.)
1885 All edit commands operate from any place on the line (not just at the
1887 beginning). Neither the `RETURN' nor the `LINE FEED' key is entered
1888 after edit commands except when noted.
1889 The M-[ multi-character commands below are DEC VT220 escape sequences
1891 generated by special keys on standard PC keyboards, such as the arrow
1892 keys. You could type them directly but they are meant to recognize the
1893 keys in question, which are indicated in parentheses.
1894 ^F Move cursor forward (right) one character.
1896 M-[C (Right arrow) Same as ^F.
1897 M-f Move cursor forward one word. (The emacs editor's idea of a
1898 word is a string of characters consisting of only letters,
1899 digits and underscores.)
1900 ^B Move cursor backward (left) one character.
1901 M-[D (Left arrow) Same as ^B.
1902 M-b Move cursor backward one word.
1903 ^A Move cursor to start of line.
1904 M-[H (Home) Same as ^A.
1905 ^E Move cursor to end of line.
1906 M-[F (End) Same as ^E.
1907 M-[Y Same as ^E.
1908 ^]char Move cursor forward to character char on current line.
1909 M-^]char Move cursor backward to character char on current line.
1910 ^X^X Interchange the cursor and mark.
1911 erase (User defined erase character as defined by the stty(1) com‐
1912 mand, usually ^H .) Delete previous character.
1913 lnext (User defined literal next character as defined by the
1914 stty(1) command, or ^V if not defined.) Removes the next
1915 character's editing features (if any).
1916 ^D Delete current character.
1917 M-[3~ (Forward delete) Same as ^D.
1918 M-d Delete current word.
1919 M-^H (Meta-backspace) Delete previous word.
1920 M-h Delete previous word.
1921 M-^? (Meta-DEL) Delete previous word (if your interrupt character
1922 is ^? (DEL, the default) then this command will not work).
1923 ^T Transpose current character with previous character and ad‐
1924 vance the cursor in emacs mode. Transpose two previous char‐
1925 acters in gmacs mode.
1926 ^C Capitalize current character.
1927 M-c Capitalize current word.
1928 M-l Change the current word to lower case.
1929 ^K Delete from the cursor to the end of the line. If preceded
1930 by a numerical parameter whose value is less than the current
1931 cursor position, then delete from given position up to the
1932 cursor. If preceded by a numerical parameter whose value is
1933 greater than the current cursor position, then delete from
1934 cursor up to given cursor position.
1935 ^W Kill from the cursor to the mark.
1936 M-p Push the region from the cursor to the mark on the stack.
1937 kill (User defined kill character as defined by the stty command,
1938 usually ^U .) Kill the entire current line. If two kill
1939 characters are entered in succession, all kill characters
1940 from then on cause a line feed (useful when using paper ter‐
1941 minals). A subsequent pair of kill characters undoes this
1942 change.
1943 ^Y Restore last item removed from line. (Yank item back to the
1944 line.)
1945 ^L Line feed and print current line.
1946 M-^L Clear the screen.
1947 ^@ (Null character) Set mark.
1948 M-space (Meta space) Set mark.
1949 ^J (New line) Execute the current line.
1950 ^M (Return) Execute the current line.
1951 eof End-of-file character, normally ^D, is processed as an End-
1952 of-file only if the current line is null.
1953 ^P Fetch previous command. Each time ^P is entered the previous
1954 command back in time is accessed. Moves back one line when
1955 not on the first line of a multi-line command.
1956 M-[A (Up arrow) If the cursor is at the end of the line, it is
1957 equivalent to ^R with string set to the contents of the cur‐
1958 rent line. Otherwise, it is equivalent to ^P.
1959 M-< Fetch the least recent (oldest) history line.
1960 M-> Fetch the most recent (youngest) history line.
1961 ^N Fetch next command line. Each time ^N is entered the next
1962 command line forward in time is accessed.
1963 M-[B (Down arrow) Equivalent to ^N.
1964 ^Rstring Reverse search history for a previous command line containing
1965 string. If a parameter of zero is given, the search is for‐
1966 ward. String is terminated by a `RETURN' or `NEW LINE'. If
1967 string is preceded by a ^, the matched line must begin with
1968 string. If string is omitted, then the next command line
1969 containing the most recent string is accessed. In this case
1970 a parameter of zero reverses the direction of the search.
1971 ^O Operate - Execute the current line and fetch the next line
1972 relative to current line from the history file.
1973 M-digits (Escape) Define numeric parameter, the digits are taken as a
1974 parameter to the next command. The commands that accept a
1975 parameter are ^F, ^B, erase, ^C, ^D, ^K, ^R, ^P, ^N, ^], M-.,
1976 M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l, M-^H, and the
1977 arrow keys and forward-delete key.
1978 M-letter Soft-key - Your alias list is searched for an alias by the
1979 name _letter and if an alias of this name is defined, its
1980 value will be inserted on the input queue. The letter must
1981 not be one of the above meta-functions.
1982 M-[letter Soft-key - Your alias list is searched for an alias by the
1983 name __letter and if an alias of this name is defined, its
1984 value will be inserted on the input queue. This can be used
1985 to program function keys on many terminals.
1986 M-. The last word of the previous command is inserted on the
1987 line. If preceded by a numeric parameter, the value of this
1988 parameter determines which word to insert rather than the
1989 last word.
1990 M-_ Same as M-..
1991 M-* Attempt file name generation on the current word. An aster‐
1992 isk is appended if the word doesn't match any file or contain
1993 any special pattern characters.
1994 M-ESC Command or file name completion as described above.
1995 ^I tab Attempts command or file name completion as described above.
1996 If a partial completion occurs, repeating this will behave as
1997 if M-= were entered. If no match is found or entered after
1998 space, a tab is inserted.
1999 M-= If not preceded by a numeric parameter, it generates the list
2000 of matching commands or file names as described above. Oth‐
2001 erwise, the word under the cursor is replaced by the item
2002 corresponding to the value of the numeric parameter from the
2003 most recently generated command or file list. If the cursor
2004 is not on a word, it is inserted instead.
2005 ^U Multiply parameter of next command by 4.
2006 \ If the backslashctrl shell option is on (which is the default
2007 setting), this escapes the next character. Editing charac‐
2008 ters, the user's erase, kill and interrupt (normally ^C)
2009 characters may be entered in a command line or in a search
2010 string if preceded by a \. The \ removes the next charac‐
2011 ter's editing features (if any). See also lnext which is not
2012 subject to any shell option.
2013 M-^V Display version of the shell.
2014 M-# If the line does not begin with a #, a # is inserted at the
2015 beginning of the line and after each new-line, and the line
2016 is entered. This causes a comment to be inserted in the his‐
2017 tory file. If the line begins with a #, the # is deleted and
2018 one # after each new-line is also deleted.
2019 Vi Editing Mode.
2021 There are two typing modes. Initially, when you enter a command you
2022 are in the input mode. To edit, the user enters control mode by typing
2023 ESC (033) and moves the cursor to the point needing correction and then
2024 inserts or deletes characters or words as needed. Most control com‐
2025 mands accept an optional repeat count prior to the command.
2026 The notation for control characters used below is ^ followed by a char‐
2028 acter. For instance, ^H is entered by holding down the Control key and
2029 pressing H. ^[ (Control+[) is equivalent to the ESC key. The notation
2030 for escape sequences is ^[ followed by one or more characters.
2031 The ^[[ (ESC [) multi-character commands below are DEC VT220 escape se‐
2033 quences generated by special keys on standard PC keyboards, such as the
2034 arrow keys, which are indicated in parentheses. When in input mode,
2035 these keys will switch you to control mode before performing the asso‐
2036 ciated action. These sequences can use preceding repeat count parame‐
2037 ters, but only when the ^[ and the subsequent [ are entered into the
2038 input buffer at the same time, such as when pressing one of those keys.
2039 Input Edit Commands
2041 By default the editor is in input mode.
2042 erase (User defined erase character as defined by the stty
2043 command, usually ^H or #.) Delete previous character.
2044 ^W Delete the previous blank separated word. On some
2045 systems the viraw option may be required for this to
2046 work.
2047 eof As the first character of the line causes the shell to
2048 terminate unless the ignoreeof option is set. Other‐
2049 wise this character is ignored.
2050 lnext (User defined literal next character as defined by the
2051 stty(1) or ^V if not defined.) Removes the next char‐
2052 acter's editing features (if any). On some systems
2053 the viraw option may be required for this to work.
2054 \ If the backslashctrl shell option is on (which is the
2055 default setting), this escapes the next erase or kill
2056 character.
2057 ^I tab Attempts command or file name completion as described
2058 above and returns to input mode. If a partial comple‐
2059 tion occurs, repeating this will behave as if = were
2060 entered from control mode. If no match is found or
2061 entered after space, a tab is inserted.
2062 Motion Edit Commands
2063 These commands will move the cursor.
2064 [count]l Cursor forward (right) one character.
2065 [count]^[[C
2066 (Right arrow) Same as l.
2067 [count]w Cursor forward one alphanumeric word.
2068 [count]W Cursor to the beginning of the next word that follows
2069 a blank.
2070 [count]e Cursor to end of word.
2071 [count]E Cursor to end of the current blank delimited word.
2072 [count]h Cursor backward (left) one character.
2073 [count]^[[D
2074 (Left arrow) Same as h.
2075 [count]b Cursor backward one word.
2076 [count]B Cursor to preceding blank separated word.
2077 [count]| Cursor to column count.
2078 [count]fc Find the next character c in the current line.
2079 [count]Fc Find the previous character c in the current line.
2080 [count]tc Equivalent to f followed by h.
2081 [count]Tc Equivalent to F followed by l.
2082 [count]; Repeats count times, the last single character find
2083 command, f, F, t, or T.
2084 [count], Reverses the last single character find command count
2085 times.
2086 0 Cursor to start of line.
2087 ^[[H (Home) Same as 0.
2088 ^ Cursor to first non-blank character in line.
2089 $ Cursor to end of line.
2090 ^[[F (End) Same as $.
2091 ^[[Y Same as $.
2092 % Moves to balancing (, ), {, }, [, or ]. If cursor is
2093 not on one of the above characters, the remainder of
2094 the line is searched for the first occurrence of one
2095 of the above characters first.
2096 Search Edit Commands
2097 These commands access your command history.
2098 [count]k Fetch previous command. Each time k is entered the
2099 previous command back in time is accessed.
2100 [count]- Equivalent to k.
2101 [count]^[[A
2102 (Up arrow) If cursor is at the end of the line it is
2103 equivalent to / with string set to the contents of the
2104 current line. Otherwise, it is equivalent to k.
2105 [count]j Fetch next command. Each time j is entered the next
2106 command forward in time is accessed.
2107 [count]+ Equivalent to j.
2108 [count]^[[B
2109 (Down arrow) Equivalent to j.
2110 [count]G The command number count is fetched. The default is
2111 the least recent history command.
2112 /string Search backward through history for a previous command
2113 containing string. String is terminated by a `RETURN'
2114 or `NEW LINE'. If string is preceded by a ^, the
2115 matched line must begin with string. If string is
2116 null, the previous string will be used.
2117 ?string Same as / except that search will be in the forward
2118 direction.
2119 n Search for next match of the last pattern to / or ?
2120 commands.
2121 N Search for next match of the last pattern to / or ?,
2122 but in reverse direction.
2123 Text Modification Edit Commands
2124 These commands will modify the line.
2125 a Enter input mode and enter text after the current
2126 character.
2127 A Append text to the end of the line. Equivalent to $a.
2128 [count]cmotion
2129 c[count]motion
2130 Delete current character through the character that
2131 motion would move the cursor to and enter input mode.
2132 If motion is c, the entire line will be deleted and
2133 input mode entered.
2134 C Delete the current character through the end of line
2135 and enter input mode. Equivalent to c$.
2136 S Equivalent to cc.
2137 [count]s Replace characters under the cursor in input mode.
2138 D Delete the current character through the end of line.
2139 Equivalent to d$.
2140 [count]dmotion
2141 d[count]motion
2142 Delete current character through the character that
2143 motion would move to. If motion is d , the entire
2144 line will be deleted.
2145 i Enter input mode and insert text before the current
2146 character.
2147 I Insert text before the beginning of the line. Equiva‐
2148 lent to 0i.
2149 [count]P Place the previous text modification before the cur‐
2150 sor.
2151 [count]p Place the previous text modification after the cursor.
2152 R Enter input mode and replace characters on the screen
2153 with characters you type overlay fashion.
2154 [count]rc Replace the count character(s) starting at the current
2155 cursor position with c, and advance the cursor.
2156 [count]x Delete current character.
2157 [count]^[[3~
2158 (Forward delete) Same as x.
2159 [count]X Delete preceding character.
2160 [count]. Repeat the previous text modification command.
2161 [count]∼ Invert the case of the count character(s) starting at
2162 the current cursor position and advance the cursor.
2163 [count]_ Causes the count word of the previous command to be
2164 appended and input mode entered. The last word is
2165 used if count is omitted.
2166 * Causes an * to be appended to the current word and
2167 file name generation attempted. If no match is found,
2168 it rings the bell. Otherwise, the word is replaced by
2169 the matching pattern and input mode is entered.
2170 \ Command or file name completion as described above.
2171 Other Edit Commands
2172 Miscellaneous commands.
2173 [count]ymotion
2174 y[count]motion
2175 Yank current character through character that motion
2176 would move the cursor to and puts them into the delete
2177 buffer. The text and cursor are unchanged.
2178 yy Yanks the entire line.
2179 Y Yanks from current position to end of line. Equiva‐
2180 lent to y$.
2181 u Undo the last text modifying command.
2182 U Undo all the text modifying commands performed on the
2183 line.
2184 [count]v Returns the command hist -e ${VISUAL:-${EDITOR:-vi}}
2185 count in the input buffer. If count is omitted, then
2186 the current line is used.
2187 ^L Line feed and print current line. Has effect only in
2188 control mode.
2189 ^J (New line) Execute the current line, regardless of
2190 mode.
2191 ^M (Return) Execute the current line, regardless of mode.
2192 # If the first character of the command is a #, then
2193 this command deletes this # and each # that follows a
2194 newline. Otherwise, sends the line after inserting a
2195 # in front of each line in the command. Useful for
2196 causing the current line to be inserted in the history
2197 as a comment and uncommenting previously commented
2198 commands in the history file.
2199 [count]= If count is not specified, it generates the list of
2200 matching commands or file names as described above.
2201 Otherwise, the word under the cursor is replaced by
2202 the count item from the most recently generated com‐
2203 mand or file list. If the cursor is not on a word, it
2204 is inserted instead.
2205 @letter Your alias list is searched for an alias by the name
2206 _letter and if an alias of this name is defined, its
2207 value will be inserted on the input queue for process‐
2208 ing.
2209 ^V Display version of the shell.
2210 Built-in Commands.
2212 The simple-commands listed below are built in to the shell and are exe‐
2213 cuted in the same process as the shell. The effects of any added In‐
2214 put/Output redirections are local to the command, except for the exec
2215 and redirect commands. Unless otherwise indicated, the output is writ‐
2216 ten on standard output (file descriptor 1) and the exit status, when
2217 there is no syntax error, is zero. Except for :, true, false, and
2218 echo, all built-in commands accept -- to indicate end of options, and
2219 are self-documenting.
2220 The self-documenting commands interpret the option --man as a request
2222 to display that command's own manual page, --help as a request to dis‐
2223 play the OPTIONS section from their manual page, and -? as a request
2224 to print a brief usage message. All these are processed as error mes‐
2225 sages, so they are written on standard error (file descriptor 2) and to
2226 pipe them into a pager such as more(1) you need to add a 2>&1 redirect‐
2227 ion before the |. The display of boldface text depends on whether stan‐
2228 dard error is on a terminal, so is disabled when using a pager. Export‐
2229 ing the ERROR_OPTIONS environment variable with a value containing em‐
2230 phasis will force this on; a value containing noemphasis forces it off.
2231 The test/[ command needs an additional -- argument to recognize self-
2232 documentation options, e.g. test --man --. The exec and redirect com‐
2233 mands, as they make redirections permanent, should use self-documenta‐
2234 tion options in a subshell when redirecting, for example: (redirect
2235 --man) 2>&1. There are advanced output options as well; see getopts
2236 --man for more information.
2237 Commands that are preceded by a † symbol below are special built-
2239 in commands and are treated specially in the following ways:
2240 1. Variable assignment lists preceding the command remain in effect
2241 when the command completes.
2242 2. I/O redirections are processed after variable assignments.
2243 3. Errors cause a script that contains them to abort.
2244 4. They are not valid function names.
2245 Commands that are preceded by a ‡ symbol below are declaration com‐
2246 mands. Any following words that are in the format of a variable as‐
2247 signment are expanded with the same rules as a variable assignment.
2248 This means that tilde expansion is performed after the = sign, array
2249 assignments of the form varname=(assign_list) are supported, and field
2250 splitting and file name generation are not performed.
2251 † : [ arg ... ]
2253 The command only expands parameters.
2254 † . name [ arg ... ]
2256 If name is a function defined with the function name reserved
2257 word syntax, the function is executed in the current environment
2258 (as if it had been defined with the name() syntax). Otherwise
2259 if name refers to a file, the file is read in its entirety and
2260 the commands are executed in the current shell environment. The
2261 search path specified by PATH is used to find the directory con‐
2262 taining the file. If any arguments arg are given, they become
2263 the positional parameters while processing the . command and
2264 the original positional parameters are restored upon completion.
2265 Otherwise the positional parameters are unchanged. The exit
2266 status is the exit status of the last command executed.
2267 [ expression ]
2269 The [ command is the same as test, with the exception that an
2270 additional closing ] argument is required. See test below.
2271 alias [ -ptx ] [ name[ =value ] ] ...
2273 alias with no arguments prints the list of aliases in the form
2274 name=value on standard output. The -p option causes the word
2275 alias to be inserted before each one. When one or more argu‐
2276 ments are given, an alias is defined for each name whose value
2277 is given. A trailing space in value causes the next word to be
2278 checked for alias substitution. With the -t option, each name
2279 is looked up as a command in $PATH and its path is added to the
2280 hash table as a 'tracked alias'. If no name is given, this
2281 prints the hash table. See hash. Without the -t option, for
2282 each name in the argument list for which no value is given, the
2283 name and value of the alias is printed. The obsolete -x option
2284 has no effect. The exit status is non-zero if a name is given,
2285 but no value, and no alias has been defined for the name.
2286 autoload name ...
2288 Marks each name undefined so that the FPATH variable will be
2289 searched to find the function definition when the function is
2290 referenced. The same as typeset -fu.
2291 bg [ job... ]
2293 This command is only on systems that support job control. Puts
2294 each specified job into the background. The current job is put
2295 in the background if job is not specified. See Jobs for a de‐
2296 scription of the format of job.
2297 † break [ n ]
2299 Exit from the enclosing for, while, until, or select loop, if
2300 any. If n is specified, then break n levels.
2301 builtin [ -ds ] [ -f file ] [ name ... ]
2303 If name is not specified, and no -f option is specified, the
2304 built-ins are printed on standard output. The -s option prints
2305 only the special built-ins. Otherwise, each name represents the
2306 pathname whose basename is the name of the built-in. The entry
2307 point function name is determined by prepending b_ to the built-
2308 in name. A built-in specified by a pathname will only be exe‐
2309 cuted when that pathname would be found during the path search.
2310 Built-ins found in libraries loaded via the .paths file will as‐
2311 sociate with the pathname of the directory containing the .paths
2312 file.
2313 The ISO C/C++ prototype is b_mycommand(int argc, char *argv[],
2315 void *context) for the builtin command mycommand where argv is
2316 array an of argc elements and context is an optional pointer to
2317 a Shell_t structure as described in <ast/shell.h>.
2318 Special built-ins cannot be bound to a pathname or deleted. The
2320 -d option deletes each of the given built-ins. On systems that
2321 support dynamic loading, the -f option names a shared library
2322 containing the code for built-ins. The shared library prefix
2323 and/or suffix, which depend on the system, can be omitted. Once
2324 a library is loaded, its symbols become available for subsequent
2325 invocations of builtin. Multiple libraries can be specified
2326 with separate invocations of the builtin command. Libraries are
2327 searched in the reverse order in which they are specified. When
2328 a library is loaded, it looks for a function in the library
2329 whose name is lib_init() and invokes this function with an argu‐
2330 ment of 0.
2331 cd [ -LP ] [ arg ]
2333 cd [ -LP ] old new
2334 This command can be in either of two forms. In the first form
2335 it changes the current directory to arg. If arg is - the direc‐
2336 tory is changed to the previous directory. The shell variable
2337 HOME is the default arg. The variable PWD is set to the current
2338 directory. The shell variable CDPATH defines the search path
2339 for the directory containing arg. Alternative directory names
2340 are separated by a colon (:). The default path is <null> (spec‐
2341 ifying the current directory). Note that the current directory
2342 is specified by a null path name, which can appear immediately
2343 after the equal sign or between the colon delimiters anywhere
2344 else in the path list. If arg begins with a / then the search
2345 path is not used. Otherwise, each directory in the path is
2346 searched for arg.
2347 The second form of cd substitutes the string new for the string
2348 old in the current directory name, PWD, and tries to change to
2349 this new directory.
2350 By default, symbolic link names are treated literally when find‐
2351 ing the directory name. This is equivalent to the -L option.
2352 The -P option causes symbolic links to be resolved when deter‐
2353 mining the directory. The last instance of -L or -P on the com‐
2354 mand line determines which method is used.
2355 The cd command may not be executed by rksh.
2356 command [ -pvxV ] name [ arg ... ]
2358 With the -v option, command is equivalent to the built-in whence
2359 command described below. The -V option causes command to act
2360 like whence -v.
2361 Without the -v or -V options, command executes name with the ar‐
2363 guments given by arg. Functions and aliases will not be
2364 searched for when finding name. If name refers to a special
2365 built-in, as marked with † in this manual, command disables the
2366 special properties described above for that mark, executing the
2367 command as a regular built-in. (For example, using command set
2368 -o option-name prevents a script from terminating when an in‐
2369 valid option name is given.)
2370 The -p option causes the operating system's standard utilities
2372 path (as output by getconf PATH) to be searched rather than the
2373 one defined by the value of PATH.
2374 The -x option runs name as an external command, bypassing built-
2376 ins. If the arguments contain at least one word that expands to
2377 multiple arguments, such as "$@" or *.txt, then the -x option
2378 also allows executing external commands with argument lists that
2379 are longer than the operating system allows. This functionality
2380 is similar to xargs(1) but is easier to use. The shell does this
2381 by invoking the external command multiple times if needed, di‐
2382 viding the expanded argument list over the invocations. Any ar‐
2383 guments that come before the first word that expands to multiple
2384 arguments, as well as any that follow the last such word, are
2385 considered static arguments and are repeated for each invoca‐
2386 tion. This allows each invocation to use the same command op‐
2387 tions, as well as the same trailing destination arguments for
2388 commands like cp(1) or mv(1). When all invocations are com‐
2389 pleted, command -x exits with the status of the invocation that
2390 had the highest exit status. (Note that command -x may still
2391 fail with an "argument list too long" error if a single argument
2392 exceeds the maximum length of the argument list, or if a long
2393 arguments list contains no word that expands to multiple argu‐
2394 ments.)
2395 ‡ compound vname[=value] ...
2397 Causes each vname to be a compound variable. The same as type‐
2398 set -C.
2399 † continue [ n ]
2401 Resume the next iteration of the enclosing for, while, until, or
2402 select loop. If n is specified, then resume at the n-th enclos‐
2403 ing loop.
2404 disown [ job... ]
2406 Causes the shell not to send a HUP signal to each given job, or
2407 all active jobs if job is omitted, when a login shell termi‐
2408 nates.
2409 echo [ arg ... ]
2411 When the first arg does not begin with a -, and none of the ar‐
2412 guments contain a \, then echo prints each of its arguments sep‐
2413 arated by a space and terminated by a new-line. Otherwise, the
2414 behavior of echo is system dependent and print or printf de‐
2415 scribed below should be used. See echo(1) for usage and de‐
2416 scription.
2417 ‡ enum [ -i ] type[=(value ...) ]
2419 Creates a declaration command named type that is an integer type
2420 that allows one of the specified values as enumeration names.
2421 If =(value ...) is omitted, then type must be an indexed array
2422 variable with at least two elements and the values are taken
2423 from this array variable. If -i is specified the values are
2424 case-insensitive. Declaration commands are created as special
2425 builtins that cannot be removed or overridden by shell func‐
2426 tions.
2427 † eval [ arg ... ]
2429 The arguments are read as input to the shell and the resulting
2430 command(s) executed.
2431 † exec [ -c ] [ -a name ] [ arg ... ]
2433 If arg is given, the command specified by the arguments is exe‐
2434 cuted in place of this shell without creating a new process.
2435 The -c option causes the environment to be cleared before apply‐
2436 ing variable assignments associated with the exec invocation.
2437 The -a option causes name rather than the first arg, to become
2438 argv[0] for the new process. If arg is not given and only I/O
2439 redirections are given, then this command persistently modifies
2440 file descriptors as in redirect.
2441 † exit [ n ]
2443 Causes the shell to exit with the exit status specified by n.
2444 The value will be the least significant 8 bits of the specified
2445 status. If n is omitted, then the exit status is that of the
2446 last command executed. An end-of-file will also cause the shell
2447 to exit except for a shell which has the ignoreeof option (see
2448 set below) turned on.
2449 †‡ export [ -p ] [ name[=value] ] ...
2451 If name is not given, the names and values of each variable with
2452 the export attribute are printed with the values quoted in a
2453 manner that allows them to be re-input. The export command is
2454 the same as typeset -x except that if you use export within a
2455 function, no local variable is created. The -p option causes
2456 the word export to be inserted before each one. Otherwise, the
2457 given names are marked for automatic export to the environment
2458 of subsequently-executed commands.
2459 false Does nothing, and exits 1. Used with until for infinite loops.
2461 fc [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]
2463 fc -s [ old=new ] [ command ]
2464 The same as hist.
2465 fg [ job... ]
2467 This command is only on systems that support job control. Each
2468 job specified is brought to the foreground and waited for in the
2469 specified order. Otherwise, the current job is brought into the
2470 foreground. See Jobs for a description of the format of job.
2471 ‡ float vname[=value] ...
2473 Declares each vname to be a long floating point number. The
2474 same as typeset -lE.
2475 functions [ -Stux ] [ name ... ]
2477 Lists functions. The same as typeset -f.
2478 getconf [ name [ pathname ] ]
2480 Prints the current value of the configuration parameter given by
2481 name. The configuration parameters are defined by the IEEE
2482 POSIX 1003.1 and IEEE POSIX 1003.2 standards. (See pathconf(2)
2483 and sysconf(3).) The pathname argument is required for parame‐
2484 ters whose value depends on the location in the file system. If
2485 no arguments are given, getconf prints the names and values of
2486 the current configuration parameters. The pathname / is used
2487 for each of the parameters that requires pathname.
2488 getopts [ -a name ] optstring vname [ arg ... ]
2490 Checks arg for legal options. If arg is omitted, the positional
2491 parameters are used. An option argument begins with a + or a -.
2492 An option not beginning with + or - or the argument -- ends the
2493 options. Options beginning with + are only recognized when opt‐
2494 string begins with a +. optstring contains the letters that
2495 getopts recognizes. If a letter is followed by a :, that option
2496 is expected to have an argument. The options can be separated
2497 from the argument by blanks. The option -? causes getopts to
2498 generate a usage message on standard error. The -a argument can
2499 be used to specify the name to use for the usage message, which
2500 defaults to $0.
2501 getopts places the next option letter it finds inside variable
2502 vname each time it is invoked. The option letter will be
2503 prepended with a + when arg begins with a +. The index of the
2504 next arg is stored in OPTIND. The option argument, if any, gets
2505 stored in OPTARG.
2506 A leading : in optstring causes getopts to store the letter of
2507 an invalid option in OPTARG, and to set vname to ? for an un‐
2508 known option and to : when a required option argument is miss‐
2509 ing. Otherwise, getopts prints an error message. The exit sta‐
2510 tus is non-zero when there are no more options.
2511 There is no way to specify any of the options :, +, -, ?, [, and
2512 ]. The option # can only be specified as the first option.
2513 hash [ -r ] [ utility ]
2515 hash displays or modifies the hash table with the locations of
2516 recently used programs. If given no arguments, it lists all com‐
2517 mand/path associations (a.k.a. 'tracked aliases') in the hash
2518 table. Otherwise, hash performs a PATH search for each utility
2519 supplied and adds the result to the hash table. The -r option
2520 empties the hash table. This can also be achieved by resetting
2521 PATH.
2522 hist [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]
2524 hist -s [ old=new ] [ command ]
2525 In the first form, a range of commands from first to last is se‐
2526 lected from the last HISTSIZE commands that were typed at the
2527 terminal. The arguments first and last may be specified as a
2528 number or as a string. A string is used to locate the most re‐
2529 cent command starting with the given string. A negative number
2530 is used as an offset to the current command number. If the -l
2531 option is selected, the commands are listed on standard output.
2532 Otherwise, the editor program ename is invoked on a file con‐
2533 taining these keyboard commands. If ename is not supplied, then
2534 the value of the variable HISTEDIT is used. If HISTEDIT is not
2535 set, then FCEDIT (default /bin/ed) is used as the editor. When
2536 editing is complete, the edited command(s) is executed if the
2537 changes have been saved. If last is not specified, then it will
2538 be set to first. If first is not specified, the default is the
2539 previous command for editing and -16 for listing. The option -r
2540 reverses the order of the commands and the option -n suppresses
2541 command numbers when listing. In the second form, command is
2542 interpreted as first described above and defaults to the last
2543 command executed. The resulting command is executed after the
2544 optional substitution old=new is performed. The option -N
2545 causes hist to start num commands back.
2546 ‡ integer vname[=value] ...
2548 Declares each vname to be a long integer number. The same as
2549 typeset -li.
2550 jobs [ -lnp ] [ job ... ]
2552 Lists information about each given job; or all active jobs if
2553 job is omitted. The -l option lists process ids in addition to
2554 the normal information. The -n option only displays jobs that
2555 have stopped or exited since last notified. The -p option
2556 causes only the process group to be listed. See Jobs for a de‐
2557 scription of the format of job.
2558 kill [ -s signame ] job ...
2560 kill [ -n signum ] job ...
2561 kill -Ll [ sig ... ]
2562 Sends either the TERM (terminate) signal or the specified signal
2563 to the specified jobs or processes. Signals are either given by
2564 number with the -n option or by name with the -s option (as
2565 given in <signal.h>, stripped of the prefix ``SIG'' with the ex‐
2566 ception that SIGCLD is named CHLD). For backward compatibility,
2567 the n and s can be omitted and the number or name placed immedi‐
2568 ately after the -. If the signal being sent is TERM (terminate)
2569 or HUP (hangup), then the job or process will be sent a CONT
2570 (continue) signal if it is stopped. The argument job can be the
2571 process id of a process that is not a member of one of the ac‐
2572 tive jobs. See Jobs for a description of the format of job. In
2573 the third form, kill -l, or kill -L, if sig is not specified,
2574 the signal names are listed. The -l option list only the signal
2575 names. -L options lists each signal name and corresponding num‐
2576 ber. Otherwise, for each sig that is a name, the corresponding
2577 signal number is listed. For each sig that is a number, the
2578 signal name corresponding to the least significant 8 bits of sig
2579 is listed.
2580 let arg ...
2582 Each arg is a separate arithmetic expression to be evaluated.
2583 let only recognizes octal constants starting with 0 when the set
2584 option letoctal is on. See Arithmetic Evaluation above, for a
2585 description of arithmetic expression evaluation.
2586 The exit status is 0 if the value of the last expression is non-
2587 zero, and 1 otherwise.
2588 ‡ nameref vname[=refname] ...
2590 Declares each vname to be a variable name reference. The same
2591 as typeset -n.
2592 print [ -CRenprsv ] [ -u unit ] [ -f format ] [ arg ... ]
2594 With no options or with option - or --, each arg is printed on
2595 standard output. The -f option causes the arguments to be
2596 printed as described by printf. In this case, any e, n, r, R
2597 options are ignored. Otherwise, unless the -C, -R, -r, or -v
2598 are specified, the following escape conventions will be applied:
2599 \a The alert character (ascii 07).
2600 \b The backspace character (ascii 010).
2601 \c Causes print to end without processing more arguments and
2602 not adding a new-line.
2603 \f The formfeed character (ascii 014).
2604 \n The newline character (ascii 012).
2605 \r The carriage return character (ascii 015).
2606 \t The tab character (ascii 011).
2607 \v The vertical tab character (ascii 013).
2608 \E The escape character (ascii 033).
2609 \\ The backslash character \.
2610 \0x The character defined by the 1, 2, or 3-digit octal
2611 string given by x.
2612 The -R option will print all subsequent arguments and options
2614 other than -n. The -e causes the above escape conventions to be
2615 applied. This is the default behavior. It reverses the effect
2616 of an earlier -r. The -p option causes the arguments to be
2617 written onto the pipe of the process spawned with |& instead of
2618 standard output. The -v option treats each arg as a variable
2619 name and writes the value in the printf %B format. The -C op‐
2620 tion treats each arg as a variable name and writes the value in
2621 the printf %#B format. The -s option causes the arguments to be
2622 written onto the history file instead of standard output. The
2623 -u option can be used to specify a one digit file descriptor
2624 unit number unit on which the output will be placed. The de‐
2625 fault is 1. If the option -n is used, no new-line is added to
2626 the output.
2627 printf format [ arg ... ]
2629 The arguments arg are printed on standard output in accordance
2630 with the ANSI-C formatting rules associated with the format
2631 string format. If the number of arguments exceeds the number of
2632 format specifications, the format string is reused to format re‐
2633 maining arguments. The following extensions can also be used:
2634 %b A %b format can be used instead of %s to cause escape se‐
2635 quences in the corresponding arg to be expanded as de‐
2636 scribed in print.
2637 %B A %B option causes each of the arguments to be treated as
2638 variable names and the binary value of variable will be
2639 printed. The alternate flag # causes a compound variable
2640 to be output on a single line. This is most useful for
2641 compound variables and variables whose attribute is -b.
2642 %H A %H format can be used instead of %s to cause characters
2643 in arg that are special in HTML and XML to be output as
2644 their entity name. The alternate flag # formats the out‐
2645 put for use as a URI.
2646 %p A %p format will convert the given number to hexadecimal.
2647 %P A %P format can be used instead of %s to cause arg to be
2648 interpreted as an extended regular expression and be
2649 printed as a shell pattern.
2650 %q A %q format can be used instead of %s to cause the re‐
2651 sulting string to be quoted in a manner than can be rein‐
2652 put to the shell. When q is preceded by the alternative
2653 format specifier, #, the string is quoted in manner suit‐
2654 able as a field in a .csv format file.
2655 %(date-format)T
2656 A %(date-format)T format can be used to treat an argument
2657 as a date/time string and to format the date/time accord‐
2658 ing to the date-format.
2659 %Q A %Q format will convert the given number of seconds to
2660 readable time.
2661 %R A %R format can be used instead of %s to cause arg to be
2662 interpreted as a shell pattern and to be printed as an
2663 extended regular expression.
2664 %Z A %Z format will output a byte whose value is 0.
2665 %d The precision field of the %d format can be followed by a
2666 . and the output base. In this case, the # flag charac‐
2667 ter causes base# to be prepended.
2668 # The # flag, when used with the %d format without an out‐
2669 put base, displays the output in powers of 1000 indicated
2670 by one of the following suffixes: k M G T P E, and when
2671 used with the %i format displays the output in powers of
2672 1024 indicated by one of the following suffixes: Ki Mi Gi
2673 Ti Pi Ei.
2674 = The = flag centers the output within the specified field
2675 width.
2676 L The L flag, when used with the %c or %s formats, treats
2677 precision as character width instead of byte count.
2678 , The , flag, when used with the %d or %f formats, sepa‐
2679 rates groups of digits with the grouping delimiter (, on
2680 groups of 3 in the C locale).
2681 pwd [ -LP ]
2683 Outputs the value of the current working directory. The -L op‐
2684 tion is the default; it prints the logical name of the current
2685 directory. If the -P option is given, all symbolic links are
2686 resolved from the name. The last instance of -L or -P on the
2687 command line determines which method is used.
2688 read [ -ACSprsv ] [ -d delim ] [ -n n ] [ [ -N n ] [ -t timeout ] [ -u
2690 unit ] [ vname?prompt ] [ vname ... ]
2691 The shell input mechanism. One line is read and is broken up
2692 into fields using the characters in IFS as separators. The es‐
2693 cape character, \, is used to remove any special meaning for the
2694 next character and for line continuation. The -d option causes
2695 the read to continue to the first character of delim rather than
2696 new-line. The -n option causes at most n bytes to read rather a
2697 full line but will return when reading from a slow device as
2698 soon as any characters have been read. The -N option causes ex‐
2699 actly n to be read unless an end-of-file has been encountered or
2700 the read times out because of the -t option. In raw mode, -r,
2701 the \ character is not treated specially. The first field is
2702 assigned to the first vname, the second field to the second
2703 vname, etc., with leftover fields assigned to the last vname.
2704 When vname has the binary attribute and -n or -N is specified,
2705 the bytes that are read are stored directly into the variable.
2706 If the -v is specified, then the value of the first vname will
2707 be used as a default value when reading from a terminal device.
2708 The -A option causes the variable vname to be unset and each
2709 field that is read to be stored in successive elements of the
2710 indexed array vname. The -C option causes the variable vname to
2711 be read as a compound variable. Blanks will be ignored when
2712 finding the beginning open parenthesis. The -S option causes
2713 the line to be treated like a record in a .csv format file so
2714 that double quotes can be used to allow the delimiter character
2715 and the new-line character to appear within a field. The -p op‐
2716 tion causes the input line to be taken from the input pipe of a
2717 process spawned by the shell using |&. If the -s option is
2718 present, the input will be saved as a command in the history
2719 file. The option -u can be used to specify a one digit file de‐
2720 scriptor unit unit to read from. The file descriptor can be
2721 opened with the exec special built-in command. The default
2722 value of unit n is 0. The option -t is used to specify a time‐
2723 out in seconds when reading from a terminal or pipe. If vname
2724 is omitted, then REPLY is used as the default vname. An end-of-
2725 file with the -p option causes cleanup for this process so that
2726 another can be spawned. If the first argument contains a ?, the
2727 remainder of this word is used as a prompt on standard error
2728 when the shell is interactive. The exit status is 0 unless an
2729 end-of-file is encountered or read has timed out.
2730 †‡ readonly [ -p ] [ vname[=value] ] ...
2732 If vname is not given, the names and values of each variable
2733 with the readonly attribute is printed with the values quoted in
2734 a manner that allows them to be re-inputted. The -p option
2735 causes the word readonly to be inserted before each one. Other‐
2736 wise, the given vnames are marked readonly and these names can‐
2737 not be changed by subsequent assignment. Unlike typeset -r ,
2738 readonly does not create a function-local scope and the given
2739 vnames are marked globally read-only by default. When defining
2740 a type, if the value of a readonly sub-variable is not defined
2741 the value is required when creating each instance.
2742 redirect
2744 This command only accepts input/output redirections. It can
2745 open and close files and modify file descriptors from 0 to 9 as
2746 specified by the input/output redirection list (see the In‐
2747 put/Output section above), with the difference that the effect
2748 persists past the execution of the redirect command. When in‐
2749 voking another program, file descriptors greater than 2 that
2750 were opened with this mechanism are only passed on if they are
2751 explicitly redirected to themselves as part of the invocation
2752 (e.g. 4>&4) or if the posix option is set.
2753 † return [ n ]
2755 Causes a shell function or . script to return to the invoking
2756 script with the exit status specified by n. The value will be
2757 the least significant 8 bits of the specified status. If n is
2758 omitted, then the return status is that of the last command exe‐
2759 cuted. If return is invoked while not in a function or a .
2760 script, then it behaves the same as exit.
2761 † set [ ±BCGHabefhkmnprstuvx ] [ ±o [ option ] ] ... [ ±A vname ] [
2763 arg ... ]
2764 The options for this command have meaning as follows:
2765 -A Array assignment. Unset the variable vname and assign
2766 values sequentially from the arg list. If +A is used,
2767 the variable vname is not unset first.
2768 -B Enable brace group expansion. On by default, except if
2769 ksh is invoked as sh or rsh.
2770 -C Prevents redirection > from truncating existing files.
2771 Files that are created are opened with the O_EXCL mode.
2772 Requires >| to truncate a file when turned on.
2773 -G Enables recursive file name generation. This adds the
2774 double-star pattern ** to the file generation mechanism
2775 (see File Name Generation above). By itself, it matches
2776 the recursive contents of the current directory, which
2777 is to say, all files and directories in the current di‐
2778 rectory and in all its subdirectories, sub-subdirecto‐
2779 ries, and so on. If the pathname pattern ends in **/,
2780 only directories and subdirectories are matched, includ‐
2781 ing symbolic links that point to directories. A pre‐
2782 fixed directory name is not included in the results un‐
2783 less that directory was itself found by a pattern. For
2784 example, dir/** matches the recursive contents of dir
2785 but not dir itself, whereas di[r]/** matches both dir
2786 itself and the recursive contents of dir. Symbolic
2787 links to non-directories are not followed. Symbolic
2788 links to directories are followed if they are specified
2789 literally or match a pattern as described under File
2790 Name Generation, but not if they result from a double-
2791 star pattern.
2792 -H Enable !-style history expansion similar to csh(1).
2793 -a All subsequent variables that are defined are automati‐
2794 cally exported.
2795 -b Prints job completion messages as soon as a background
2796 job changes state rather than waiting for the next
2797 prompt.
2798 -e Unless contained in a || or && command, or the command
2799 following an if while or until command or in the pipe‐
2800 line following !, if a command has a non-zero exit sta‐
2801 tus, execute the ERR trap, if set, and exit. This mode
2802 is disabled while reading profiles.
2803 -f Disables file name generation.
2804 -h Each command becomes a tracked alias when first encoun‐
2805 tered.
2806 -k (Obsolete). All variable assignment arguments are placed
2807 in the environment for a command, not just those that
2808 precede the command name.
2809 -m Background jobs will run in a separate process group and
2810 a line will print upon completion. The exit status of
2811 background jobs is reported in a completion message. On
2812 systems with job control, this option is turned on auto‐
2813 matically for interactive shells.
2814 -n Read commands and check them for syntax errors, but do
2815 not execute them. Ignored for interactive shells.
2816 -o The following argument can be one of the following op‐
2817 tion names:
2818 allexport
2819 Same as -a.
2820 backslashctrl
2821 The backslash character \ escapes the next con‐
2822 trol character in the emacs built-in editor and
2823 the next erase or kill character in the vi
2824 built-in editor. On by default.
2825 bgnice All background jobs are run at a lower priority.
2826 This is the default mode.
2827 braceexpand
2828 Same as -B.
2829 emacs Puts you in an emacs style in-line editor for
2830 command entry.
2831 errexit Same as -e.
2832 globcasedetect
2833 When this option is turned on, globbing (see
2834 File Name Generation above) and file name list‐
2835 ing and completion (see In-line Editing Options
2836 above) automatically become case-insensitive on
2837 file systems where the difference between upper-
2838 and lowercase is ignored for file names. This is
2839 transparently determined for each directory, so
2840 a path pattern that spans multiple file systems
2841 can be part case-sensitive and part case-insen‐
2842 sitive. In more precise terms, each slash-sepa‐
2843 rated path name component pattern p is treated
2844 as ~(i:p) if its parent directory exists on a
2845 case-insensitive file system. This option is
2846 only present on operating systems that support
2847 case-insensitive file systems.
2848 globstar
2849 Same as -G.
2850 gmacs Puts you in a gmacs style in-line editor for
2851 command entry.
2852 histexpand
2853 Same as -H.
2854 ignoreeof
2855 The shell will not exit on end-of-file. The
2856 command exit must be used.
2857 keyword Same as -k.
2858 letoctal
2859 The let command allows octal constants starting
2860 with 0. On by default if ksh is invoked as sh
2861 or rsh.
2862 markdirs
2863 All directory names resulting from file name
2864 generation have a trailing / appended.
2865 monitor Same as -m.
2866 multiline
2867 The built-in editors will use multiple lines on
2868 the screen for lines that are longer than the
2869 width of the screen. This may not work for all
2870 terminals.
2871 noclobber
2872 Same as -C.
2873 noexec Same as -n.
2874 noglob Same as -f.
2875 nolog Obsolete; has no effect.
2876 notify Same as -b.
2877 nounset Same as -u.
2878 pipefail
2879 A pipeline will not complete until all compo‐
2880 nents of the pipeline have completed, and the
2881 return value will be the value of the last non-
2882 zero command to fail or zero if no command has
2883 failed.
2884 posix Enables the POSIX standard mode for maximum com‐
2885 patibility with other compliant shells. At the
2886 moment that the posix option is turned on, it
2887 also turns on letoctal and turns off -B/braceex‐
2888 pand; the reverse is done when posix is turned
2889 back off. (These options can still be controlled
2890 independently in between.) Furthermore, the
2891 posix option is automatically turned on upon in‐
2892 vocation if ksh is invoked as sh or rsh. In that
2893 case, or if the option is turned on by specify‐
2894 ing -o posix on the invocation command line, the
2895 invoked shell will not set the preset aliases
2896 even if interactive, and will not import type
2897 attributes for variables (such as integer or
2898 readonly) from the environment.
2899 In addition, while on, the posix option
2900 • disables exporting variable type attributes
2901 to the environment for other ksh processes to
2902 import;
2903 • causes file descriptors > 2 to be left open
2904 when invoking another program;
2905 • disables the &> redirection shorthand;
2906 • makes the <> redirection operator default to
2907 redirecting standard input if no file de‐
2908 scriptor number precedes it; and
2909 • disables a hack that makes test -t ([ -t ])
2910 equivalent to test -t 1 ([ -t 1 ]).
2911 privileged
2912 Same as -p.
2913 showme When enabled, simple commands or pipelines pre‐
2914 ceded by a semicolon (;) will be displayed as if
2915 the xtrace option were enabled but will not be
2916 executed. Otherwise, the leading ; will be ig‐
2917 nored.
2918 trackall
2919 Same as -h.
2920 verbose Same as -v.
2921 vi Puts you in insert mode of a vi style in-line
2922 editor until you hit the escape character 033.
2923 This puts you in control mode. A return sends
2924 the line.
2925 viraw Each character is processed as it is typed in vi
2926 mode. The shell may have been compiled to force
2927 this option on at all times. Otherwise, canoni‐
2928 cal processing (line-by-line input) is initially
2929 enabled and the command line will be echoed
2930 again if the speed is 1200 baud or greater and
2931 it contains any control characters or less than
2932 one second has elapsed since the prompt was
2933 printed. The ESC character terminates canonical
2934 processing for the remainder of the command and
2935 the user can then modify the command line. This
2936 scheme has the advantages of canonical process‐
2937 ing with the type-ahead echoing of raw mode. If
2938 the viraw option is set, the terminal will al‐
2939 ways have canonical processing disabled. This
2940 mode is implicit for systems that do not support
2941 two alternate end of line delimiters, and may be
2942 helpful for certain terminals.
2943 xtrace Same as -x.
2944 If no option name is supplied, then the current option
2945 settings are printed.
2946 -p Disables processing of the $HOME/.profile file and uses
2947 the file /etc/suid_profile instead of the ENV file.
2948 This mode is on whenever the effective uid (gid) is not
2949 equal to the real uid (gid). Turning this off causes
2950 the effective uid and gid to be set to the real uid and
2951 gid.
2952 -r Enables the restricted shell. This option cannot be un‐
2953 set once set.
2954 -s Sort the positional parameters lexicographically.
2955 -t (Obsolete). Exit after reading and executing one com‐
2956 mand.
2957 -u Treat unset parameters as an error when substituting.
2958 $@ and $* are exempt.
2959 -v Print shell input lines as they are read.
2960 -x Print commands and their arguments as they are executed.
2961 -- Do not change any of the options; useful in setting $1
2962 to a value beginning with -. If no arguments follow
2963 this option then the positional parameters are unset.
2964 As an obsolete feature, if the first arg is - then the -x and -v
2966 options are turned off and the next arg is treated as the first
2967 argument. Using + rather than - causes these options to be
2968 turned off. These options can also be used upon invocation of
2969 the shell. The current set of options may be found in $-. Un‐
2970 less -A is specified, the remaining arguments are positional pa‐
2971 rameters and are assigned, in order, to $1 $2 .... If no argu‐
2972 ments are given, then the names and values of all variables are
2973 printed on the standard output.
2974 † shift [ n ]
2976 The positional parameters from $n+1 ... are renamed $1 ... ,
2977 default n is 1. The parameter n can be any arithmetic expres‐
2978 sion that evaluates to a non-negative number less than or equal
2979 to $#.
2980 sleep [ -s ] duration
2982 Suspends execution for the number of decimal seconds or frac‐
2983 tions of a second given by duration. duration can be an inte‐
2984 ger, floating point value or ISO 8601 duration specifying the
2985 length of time to sleep. The option -s causes the sleep builtin
2986 to terminate when it receives any signal. If duration is not
2987 specified in conjunction with -s, sleep will wait for a signal
2988 indefinitely.
2989 source name [ arg ... ]
2991 Same as ., except it is not treated as a special built-in com‐
2992 mand.
2993 stop job ...
2995 Sends a SIGSTOP signal to one or more processes specified by
2996 job, suspending them until they receive SIGCONT. The same as
2997 kill -s STOP.
2998 suspend
3000 Sends a SIGSTOP signal to the main shell process, suspending the
3001 script or child shell session until it receives SIGCONT (for in‐
3002 stance, when typing fg in the parent shell). Equivalent to
3003 kill -s STOP "$$", except that it accepts no operands and re‐
3004 fuses to suspend a login shell.
3005 test expression
3007 The test and [ commands execute conditional expressions similar
3008 to those specified for the [[ compound command under Conditional
3009 Expressions above, but with several important differences. The
3010 =, == and != operators test for string (in)equality without pat‐
3011 tern matching; the == variant is nonstandard and should not be
3012 used. The =∼, <, >, && and || operators are not available. Most
3013 importantly, as test and [ are simple regular commands, field
3014 splitting and file name generation are performed on all their
3015 arguments and all aspects of regular shell grammar (such as re‐
3016 direction) remain active. This is usually harmful, so care must
3017 be taken to quote arguments and expansions to avoid this. There
3018 are also certain inherent grammatical ambiguities in the expres‐
3019 sions. To avoid the many pitfalls arising from these issues, the
3020 [[ compound command should be used instead. The primary purpose
3021 of the test and [ commands is compatibility with other shells
3022 that lack [[.
3023 The test/[ command does not parse options except if there are
3025 two arguments and the second is --. To access the inline docu‐
3026 mentation with an option such as --man, you need one of the
3027 forms test --man -- or [ --man -- ].
3028 times Displays the accumulated user and system CPU times, one line
3030 with the times used by the shell and another with those used by
3031 all of the shell's child processes. No options are supported.
3032 † trap [ -p ] [ action ] [ sig ] ...
3034 The -p option causes the trap action associated with each trap
3035 as specified by the arguments to be printed with appropriate
3036 quoting. Otherwise, action will be processed as if it were an
3037 argument to eval when the shell receives signal(s) sig. Each
3038 sig can be given as a number or as the name of the signal. Trap
3039 commands are executed in order of signal number. Any attempt to
3040 set a trap on a signal that was ignored on entry to the current
3041 shell is ineffective. If action is omitted and the first sig is
3042 a number, or if action is -, then the trap(s) for each sig are
3043 reset to their original values. If action is the null string
3044 then this signal is ignored by the shell and by the commands it
3045 invokes. If sig is ERR then action will be executed whenever a
3046 command has a non-zero exit status. If sig is DEBUG then action
3047 will be executed before each command. The variable .sh.command
3048 will contain the shell-quoted arguments of the current command
3049 line when action is running. If the exit status of the trap is
3050 2 the command will not be executed. If the exit status of the
3051 trap is 255 and inside a function or a dot script, the function
3052 or dot script will return. If sig is 0 or EXIT and the trap
3053 statement is executed inside the body of a function defined with
3054 the function name syntax, then the command action is executed
3055 after the function completes. If sig is 0 or EXIT for a trap
3056 set outside any function then the command action is executed on
3057 exit from the shell. If sig is KEYBD, then action will be exe‐
3058 cuted whenever a key is read while in emacs, gmacs, or vi mode.
3059 The trap command with no arguments prints a list of commands as‐
3060 sociated with each signal number.
3061 An exit or return without an argument in a trap action will preserve
3063 the exit status of the command that invoked the trap.
3064 true Does nothing, and exits 0. Used with while for infinite loops.
3066 type [ -afpq ] name ...
3068 The same as whence -v.
3069 †‡ typeset [ ±ACHSbflmnprstux ] [ ±EFLRXZi[n] ] [ +-M [ mapname ] ]
3071 [ -T [ tname=(assign_list) ] ] [ -h str ] [ -a [type] ] [ vname[=value
3072 ] ] ...
3073 Sets attributes and values for shell variables and functions.
3074 When invoked inside a function defined with the function name
3075 syntax, a new instance of the variable vname is created, and the
3076 variable's value and type are restored when the function com‐
3077 pletes. The following list of attributes may be specified:
3078 -A Declares vname to be an associative array. Subscripts
3079 are strings rather than arithmetic expressions.
3080 -C Causes each vname to be a compound variable. If value
3081 names a compound variable, it is copied into vname. Oth‐
3082 erwise, the empty compound value is assigned to vname.
3083 -a Declares vname to be an indexed array. If type is speci‐
3084 fied, it must be the name of an enumeration type created
3085 with the enum command and it allows enumeration constants
3086 to be used as subscripts.
3087 -E Declares vname to be a double precision floating point
3088 number. If n is non-zero, it defines the number of sig‐
3089 nificant figures that are used when expanding vname.
3090 Otherwise, ten significant figures will be used.
3091 -F Declares vname to be a double precision floating point
3092 number. If n is non-zero, it defines the number of
3093 places after the decimal point that are used when expand‐
3094 ing vname. Otherwise ten places after the decimal point
3095 will be used.
3096 -H This option provides UNIX to host-name file mapping on
3097 non-UNIX machines.
3098 -L Left justify and remove leading blanks from value. If n
3099 is non-zero, it defines the width of the field, otherwise
3100 it is determined by the width of the value of first as‐
3101 signment. When the variable is assigned to, it is filled
3102 on the right with blanks or truncated, if necessary, to
3103 fit into the field. The -R option is turned off.
3104 -M Use the character mapping mapping defined by wctrans(3).
3105 such as tolower and toupper when assigning a value to
3106 each of the specified operands. When mapping is speci‐
3107 fied and there are not operands, all variables that use
3108 this mapping are written to standard output. When map‐
3109 ping is omitted and there are no operands, all mapped
3110 variables are written to standard output.
3111 -R Right justify and fill with leading blanks. If n is non-
3112 zero, it defines the width of the field, otherwise it is
3113 determined by the width of the value of first assignment.
3114 The field is left filled with blanks or truncated from
3115 the end if the variable is reassigned. The -L option is
3116 turned off.
3117 -S When used within the assign_list of a type definition, it
3118 causes the specified sub-variable to be shared by all in‐
3119 stances of the type. When used inside a function defined
3120 with the function reserved word, the specified variables
3121 will have function static scope. Otherwise, the variable
3122 is unset prior to processing the assignment list.
3123 -T If followed by tname, it creates a type named by tname
3124 using the compound assignment assign_list to tname. Oth‐
3125 erwise, it writes all the type definitions to standard
3126 output.
3127 -X Declares vname to be a double precision floating point
3128 number and expands using the %a format of ISO-C99. If n
3129 is non-zero, it defines the number of hex digits after
3130 the radix point that is used when expanding vname. The
3131 default is 10.
3132 -Z Right justify and fill with leading zeros if the first
3133 non-blank character is a digit and the -L option has not
3134 been set. Remove leading zeros if the -L option is also
3135 set. If n is non-zero, it defines the width of the
3136 field, otherwise it is determined by the width of the
3137 value of first assignment.
3138 -f The names refer to function names rather than variable
3139 names. No assignments can be made and the only other
3140 valid options are -S, -t, -u and -x. The -S can be used
3141 with discipline functions defined in a type to indicate
3142 that the function is static. For a static function, the
3143 same method will be used by all instances of that type no
3144 matter which instance references it. In addition, it can
3145 only use value of variables from the original type defi‐
3146 nition. These discipline functions cannot be redefined
3147 in any type instance. The -t option turns on execution
3148 tracing for this function. The -u option causes this
3149 function to be marked undefined. The FPATH variable will
3150 be searched to find the function definition when the
3151 function is referenced. If no options other than -f is
3152 specified, then the function definition will be displayed
3153 on standard output. If +f is specified, then a line con‐
3154 taining the function name followed by a shell comment
3155 containing the line number and path name of the file
3156 where this function was defined, if any, is displayed.
3157 The exit status can be used to determine whether the
3158 function is defined so that typeset -f .sh.math.name will
3159 return 0 when math function name is defined and non-zero
3160 otherwise.
3161 -b The variable can hold any number of bytes of data. The
3162 data can be text or binary. The value is represented by
3163 the base64 encoding of the data. If -Z is also speci‐
3164 fied, the size in bytes of the data in the buffer will be
3165 determined by the size associated with the -Z. If the
3166 base64 string assigned results in more data, it will be
3167 truncated. Otherwise, it will be filled with bytes whose
3168 value is zero. The printf format %B can be used to out‐
3169 put the actual data in this buffer instead of the base64
3170 encoding of the data.
3171 -h Used within type definitions to add information when gen‐
3172 erating information about the sub-variable on the man
3173 page. It is ignored when used outside of a type defini‐
3174 tion. When used with -f the information is associated
3175 with the corresponding discipline function.
3176 -i Declares vname to be represented internally as integer.
3177 The right hand side of an assignment is evaluated as an
3178 arithmetic expression when assigning to an integer. If n
3179 is non-zero, it defines the output arithmetic base, oth‐
3180 erwise the output base will be ten.
3181 -l Used with -i, -E or -F, to indicate long integer, or long
3182 float. Otherwise, all upper-case characters are con‐
3183 verted to lower-case. The upper-case option, -u, is
3184 turned off. Equivalent to -M tolower .
3185 -m moves or renames the variable. The value is the name of
3186 a variable whose value will be moved to vname. The orig‐
3187 inal variable will be unset. Cannot be used with any
3188 other options.
3189 -n Declares vname to be a reference to the variable whose
3190 name is defined by the value of variable vname. This is
3191 usually used to reference a variable inside a function
3192 whose name has been passed as an argument. Cannot be
3193 used with any other options.
3194 -p The name, attributes and values for the given vnames are
3195 written on standard output in a form that can be used as
3196 shell input. If +p is specified, then the values are not
3197 displayed.
3198 -r The given vnames are marked readonly and these names can‐
3199 not be changed by subsequent assignment.
3200 -s When given along with -i, restricts integer size to
3201 short.
3202 -t Tags the variables. Tags are user definable and have no
3203 special meaning to the shell.
3204 -u When given along with -i, specifies unsigned integer.
3205 Otherwise, all lower-case characters are converted to up‐
3206 per-case. The lower-case option, -l, is turned off.
3207 Equivalent to -M toupper .
3208 -x The given vnames are marked for automatic export to the
3209 environment of subsequently-executed commands. Variables
3210 whose names contain a . cannot be exported.
3211 The -i, -F, -E, and -X options cannot be specified along with
3213 -R, -L, or -Z. The -b option cannot be specified along with -L,
3214 -u, or -l. The -f, -m, -n, and -T options cannot be used to‐
3215 gether with any other option.
3216 Using + rather than - causes these options to be turned off. If
3218 no vname arguments are given, a list of vnames (and optionally
3219 the values) of the variables is printed. (Using + rather than -
3220 keeps the values from being printed.) The -p option causes
3221 typeset followed by the option letters to be printed before each
3222 name rather than the names of the options. If any option other
3223 than -p is given, only those variables which have all of the
3224 given options are printed. Otherwise, the vnames and attributes
3225 of all variables that have attributes are printed.
3226 ulimit [ -HSaMctdfxlqenupmrbiswTv ] [ limit ]
3228 Set or display a resource limit. The available resource limits
3229 are listed below. Many systems do not support one or more of
3230 these limits. The limit for a specified resource is set when
3231 limit is specified. The value of limit can be a number in the
3232 unit specified below with each resource, or the value unlimited.
3233 The -H and -S options specify whether the hard limit or the soft
3234 limit for the given resource is set. A hard limit cannot be in‐
3235 creased once it is set. A soft limit can be increased up to the
3236 value of the hard limit. If neither the H nor S option is spec‐
3237 ified, the limit applies to both. The current resource limit is
3238 printed when limit is omitted. In this case, the soft limit is
3239 printed unless H is specified. When more than one resource is
3240 specified, then the limit name and unit is printed before the
3241 value.
3242 -a Lists all of the current resource limits.
3243 -b The socket buffer size in bytes.
3244 -c The number of 512-byte blocks on the size of core dumps.
3245 -d The number of K-bytes on the size of the data area.
3246 -e The scheduling priority.
3247 -f The number of 512-byte blocks on files that can be writ‐
3248 ten by the current process or by child processes (files
3249 of any size may be read).
3250 -i The signal queue size.
3251 -l The locked address space in K-bytes.
3252 -M The address space limit in K-bytes.
3253 -m The number of K-bytes on the size of physical memory.
3254 -n The number of file descriptors plus 1.
3255 -p The number of 512-byte blocks for pipe buffering.
3256 -q The message queue size in K-bytes.
3257 -r The max real-time priority.
3258 -s The number of K-bytes on the size of the stack area.
3259 -T The number of threads.
3260 -t The number of CPU seconds to be used by each process.
3261 -u The number of processes.
3262 -v The number of K-bytes for virtual memory.
3263 -w The swap size in K-bytes.
3264 -x The number of file locks.
3265 If no option is given, -f is assumed.
3267 umask [ -S ] [ mask ]
3269 The user file-creation mask is set to mask (see umask(2)). mask
3270 can either be an octal number or a symbolic value as described
3271 in chmod(1). If a symbolic value is given, the new umask value
3272 is the complement of the result of applying mask to the comple‐
3273 ment of the previous umask value. If mask is omitted, the cur‐
3274 rent value of the mask is printed. The -S option causes the
3275 mode to be printed as a symbolic value. Otherwise, the mask is
3276 printed in octal.
3277 unalias [ -a ] name ...
3279 The aliases given by the list of names are removed from the
3280 alias list. The -a option causes all the aliases to be unset.
3281 † unset [ -fnv ] vname ...
3283 The variables given by the list of vnames are unassigned, i.e.,
3284 except for sub-variables within a type, their values and at‐
3285 tributes are erased. For sub-variables of a type, the values
3286 are reset to the default value from the type definition. Read‐
3287 only variables cannot be unset. If the -f option is set, then
3288 the names refer to function names. If the -v option is set,
3289 then the names refer to variable names. The -f option overrides
3290 -v. If -n is set and name is a name reference, then name will
3291 be unset rather than the variable that it references. The de‐
3292 fault is equivalent to -v. Unsetting LINENO, MAILCHECK, OPTARG,
3293 OPTIND, RANDOM, SECONDS, TMOUT, and _ removes their special
3294 meaning even if they are subsequently assigned to.
3295 wait [ job ... ]
3297 Wait for the specified job and report its termination status.
3298 If job is not given, then all currently active child processes
3299 are waited for. The exit status from this command is that of
3300 the last process waited for if job is specified; otherwise it is
3301 zero. See Jobs for a description of the format of job.
3302 whence [ -afpqv ] name ...
3304 For each name, indicate how it would be interpreted if used as a
3305 command name.
3306 The -v option produces a more verbose report. The -f option
3307 skips the search for functions. The -p option does a path
3308 search for name even if name is an alias, a function, or a re‐
3309 served word. The -p option turns off the -v option. The -q op‐
3310 tion causes whence to enter quiet mode. whence will return zero
3311 if all arguments are built-ins, functions, or are programs found
3312 on the path. The -a option is similar to the -v option but
3313 causes all interpretations of the given name to be reported.
3314 Invocation.
3316 If the shell is invoked by exec(2), initialization depends on argument
3317 zero ($0) as follows. If the first character of $0 is -, or the -l op‐
3318 tion is given on the invocation command line, then the shell is assumed
3319 to be a login shell. If the basename of the command path in $0 is rsh,
3320 rksh, or krsh, then the shell becomes restricted. If the basename is
3321 sh or rsh, or the -o posix option is given on the invocation command
3322 line, then the shell is initialized in full POSIX compliance mode (see
3323 the set builtin command above for more information). After this, if
3324 the shell was assumed to be a login shell, commands are read from
3325 /etc/profile and then from $HOME/.profile if it exists. Alternatively,
3326 the option -l causes the shell to be treated as a login shell. Next,
3327 for interactive shells, commands are read from the file named by ENV if
3328 the file exists, its name being determined by performing parameter ex‐
3329 pansion, command substitution, and arithmetic substitution on the value
3330 of that environment variable. If the -s option is not present and arg
3331 and a file by the name of arg exists, then it reads and executes this
3332 script. Otherwise, if the first arg does not contain a /, a path
3333 search is performed on the first arg to determine the name of the
3334 script to execute. The script arg must have execute permission and any
3335 setuid and setgid settings will be ignored. If the script is not found
3336 on the path, arg is processed as if it named a built-in command or
3337 function. Commands are then read as described below; the following op‐
3338 tions are interpreted by the shell when it is invoked:
3339 -D A list of all double quoted strings that are preceded by a $
3341 will be printed on standard output and the shell will exit.
3342 This set of strings will be subject to language translation
3343 when the locale is not C or POSIX. No commands will be exe‐
3344 cuted.
3345 -E or -o rc or --rc
3347 Read the file named by the ENV variable or by $HOME/.kshrc if
3348 not defined after the profiles. On by default for interactive
3349 shells. Use +E, +o rc or --norc to turn off.
3350 -c Read and execute a script from the first arg instead of a file.
3352 The second arg, if present, becomes that script's command name
3353 ($0). Any third and further args become positional parameters
3354 starting at $1.
3355 -s Read and execute a script from standard input instead of a
3357 file. The command name ($0) cannot be set. Any args become
3358 the positional parameters starting at $1. This option is
3359 forced on if no arg is given and is ignored if -c is also spec‐
3360 ified.
3361 -i or -o interactive or --interactive
3363 If the -i option is present or if the shell's standard input
3364 and standard error are attached to a terminal (as told by tcge‐
3365 tattr(3)), then this shell is interactive. In this case TERM
3366 is ignored (so that kill 0 does not kill an interactive shell)
3367 and INTR is caught and ignored (so that wait is interruptible).
3368 In all cases, QUIT is ignored by the shell.
3369 -r or -o restricted or --restricted
3371 If the -r option is present, the shell is a restricted shell.
3372 The remaining options and arguments are described under the set command
3374 above. An optional - as the first argument is ignored.
3375 Rksh Only.
3377 Rksh is used to set up login names and execution environments whose ca‐
3378 pabilities are more controlled than those of the standard shell. The
3379 actions of rksh are identical to those of ksh, except that the follow‐
3380 ing are disallowed:
3381 unsetting the restricted option,
3382 changing directory (see cd(1)),
3383 setting or unsetting the value or attributes of SHELL, ENV,
3384 FPATH, or PATH,
3385 specifying path or command names containing /,
3386 redirecting output (>, >|, <>, and >>),
3387 adding or deleting built-in commands,
3388 using command -p to invoke a command.
3389 The restrictions above are enforced after .profile and the ENV files
3391 are interpreted.
3392 When a command to be executed is found to be a shell procedure, rksh
3394 invokes ksh to execute it. Thus, it is possible to provide to the end-
3395 user shell procedures that have access to the full power of the stan‐
3396 dard shell, while imposing a limited menu of commands; this scheme as‐
3397 sumes that the end-user does not have write and execute permissions in
3398 the same directory.
3399 The net effect of these rules is that the writer of the .profile has
3401 complete control over user actions, by performing guaranteed setup ac‐
3402 tions and leaving the user in an appropriate directory (probably not
3403 the login directory).
3404 The system administrator often sets up a directory of commands (e.g.,
3406 /usr/rbin) that can be safely invoked by rksh.
3407
3409 Errors detected by the shell, such as syntax errors, cause the shell to
3410 return a non-zero exit status. If the shell is being used non-interac‐
3411 tively, then execution of the shell file is abandoned unless the error
3412 occurs inside a subshell in which case the subshell is abandoned. Oth‐
3413 erwise, the shell returns the exit status of the last command executed
3414 (see also the exit command above). Run time errors detected by the
3415 shell are reported by printing the command or function name and the er‐
3416 ror condition. If the line number that the error occurred on is
3417 greater than one, then the line number is also printed in square brack‐
3418 ets ([]) after the command or function name.
3419
3421 /etc/profile
3422 The system wide initialization file, executed for login shells.
3423 $HOME/.profile
3425 The personal initialization file, executed for login shells af‐
3426 ter /etc/profile.
3427 $HOME/.kshrc
3429 Default personal initialization file, executed for interactive
3430 shells when ENV is not set.
3431 /etc/suid_profile
3433 Alternative initialization file, executed instead of the per‐
3434 sonal initialization file when the real and effective user or
3435 group id do not match.
3436 /dev/null
3438 NULL device
3439
3441 cat(1), cd(1), chmod(1), cut(1), date(1), egrep(1), echo(1), emacs(1),
3442 env(1), fgrep(1), gmacs(1), grep(1), pfexec(1), stty(1), test(1),
3443 umask(1), vi(1), dup(2), exec(2), fork(2), getpwnam(3), ioctl(2),
3444 lseek(2), paste(1), pathconf(2), pipe(2), sysconf(3), umask(2),
3445 ulimit(2), wait(2), strftime(3), wctrans(3), rand(3), a.out(5), pro‐
3446 file(5), environ(7).
3447 Morris I. Bolsky and David G. Korn, The New KornShell Command and Pro‐
3449 gramming Language, Prentice Hall, 1995.
3450 POSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC
3452 9945-2, IEEE, 1993.
3453
3455 If a command is executed, and then a command with the same name is in‐
3456 stalled in a directory in the search path before the directory where
3457 the original command was found, the shell will continue to exec the
3458 original command. Use the hash command or the -t option of the alias
3459 command to correct this situation.
3460 Some very old shell scripts contain a ^ as a synonym for the pipe char‐
3462 acter |.
3463 Using the hist built-in command within a compound command will cause
3465 the whole command to disappear from the history file.
3466 The built-in command . file reads the whole file before any commands
3468 are executed. Therefore, alias and unalias commands in the file will
3469 not apply to any commands defined in the file.
3470 Traps are not processed while a job is waiting for a foreground
3472 process. Thus, a trap on CHLD won't be executed until the foreground
3473 job terminates.
3474 It is a good idea to leave a space after the comma operator in arith‐
3476 metic expressions to prevent the comma from being interpreted as the
3477 decimal point character in certain locales.
3478 KSH(1)