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 socket‐
59 pair(2) or (if the posix shell option is on) by a pipe(2) to the stan‐
60 dard input of the next command. Each command except the last is run
61 asynchronously in a subshell (see Subshells below). If the monitor or
62 pipefail option is on, or the pipeline is preceded by the reserved word
63 time, then the shell waits for all component commands in the pipeline
64 to terminate; otherwise, the shell only waits for the last component
65 command. The exit status of a pipeline is the exit status of its last
66 component command, unless the pipefail option is enabled. Each pipe‐
67 line can be preceded by the reserved word ! which causes the exit sta‐
68 tus of the pipeline to become 0 if the exit status of the last command
69 is non-zero, and 1 if the exit status of the last command is 0.
70 A list is a sequence of one or more pipelines separated by ;, &, |&,
72 &&, or ||, and optionally terminated by ;, &, or |&. Of these five
73 symbols, ;, &, and |& have equal precedence, which is lower than that
74 of && and ||. The symbols && and || also have equal precedence. A
75 semicolon (;) causes sequential execution of the preceding pipeline; an
76 ampersand (&) causes asynchronous execution of the preceding pipeline
77 (i.e., the shell does not wait for that pipeline to finish). The sym‐
78 bol |& causes asynchronous execution of the preceding pipeline with a
79 two-way pipe established to the parent shell; the standard input and
80 output of the spawned pipeline can be written to and read from by the
81 parent shell by applying the redirection operators <& and >& with arg p
82 to commands and by using -p option of the built-in commands read and
83 print described later. The symbol && (||) causes the list following it
84 to be executed only if the preceding pipeline returns a zero (non-zero)
85 value. One or more new-lines may appear in a list instead of a semi‐
86 colon, to delimit a command. The first item of the first pipeline of
87 a list that is a simple command not beginning with a redirection, and
88 not occurring within a while, until, or if list, can be preceded by a
89 semicolon. This semicolon is ignored unless the showme option is en‐
90 abled as described with the set built-in below.
91 A command is either a simple-command or one of the following. Unless
93 otherwise stated, the value returned by a command is that of the last
94 simple-command executed in the command.
95 for vname [ in word ... ] ;do list ;done
97 Each time a for command is executed, vname is set to the next
98 word taken from the in word list. If in word ... is omitted,
99 then the for command executes the do list once for each posi‐
100 tional parameter that is set starting from 1 (see Parameter Ex‐
101 pansion below). Execution ends when there are no more words in
102 the list.
103 for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
105 The arithmetic expression expr1 is evaluated first (see Arith‐
106 metic Evaluation below). The arithmetic expression expr2 is re‐
107 peatedly evaluated until it evaluates to zero and when non-zero,
108 list is executed and the arithmetic expression expr3 evaluated.
109 If any expression is omitted, then it behaves as if it evaluated
110 to 1.
111 select vname [ in word ... ] ;do list ;done
113 A select command prints on standard error (file descriptor 2)
114 the set of words, each preceded by a number. If in word ... is
115 omitted, then the positional parameters starting from 1 are used
116 instead (see Parameter Expansion below). The PS3 prompt is
117 printed and a line is read from the standard input. If this
118 line consists of the number of one of the listed words, then the
119 value of the variable vname is set to the word corresponding to
120 this number. If this line is empty, the selection list is
121 printed again. Otherwise the value of the variable vname is set
122 to the empty string. The contents of the line read from stan‐
123 dard input is saved in the variable REPLY. The list is executed
124 for each selection until a break or end-of-file is encountered.
125 If the REPLY variable is set to the empty string by the execu‐
126 tion of list, then the selection list is printed before display‐
127 ing the PS3 prompt for the next selection.
128 case word in [ [(]pattern [ | pattern ] ... ) list ;; ] ... esac
130 A case command executes the list associated with the first pat‐
131 tern that matches word. The form of the patterns is the same as
132 that used for pathname expansion (see Pathname Expansion below).
133 The ;; operator causes execution of case to terminate. If ;& is
134 used in place of ;; the next subsequent list, if any, is exe‐
135 cuted.
136 if list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi
138 The list following if is executed and, if it returns a zero exit
139 status, the list following the first then is executed. Other‐
140 wise, the list following elif is executed and, if its value is
141 zero, the list following the next then is executed. Failing
142 each successive elif list, the else list is executed. If the if
143 list has non-zero exit status and there is no else list, then
144 the if command returns a zero exit status.
145 while list ;do list ;done
147 until list ;do list ;done
148 A while command repeatedly executes the while list and, if the
149 exit status of the last command in the list is zero, executes
150 the do list; otherwise the loop terminates. If no commands in
151 the do list are executed, then the while command returns a zero
152 exit status; until may be used in place of while to negate the
153 loop termination test.
154 while inputredirection ;do list ;done
156 Filescan loop. This is defined by a lone input redirection fol‐
157 lowing while (see Input/Output below). It is faster than using
158 the read built-in command in a regular while loop. The shell
159 reads lines from the file or stream opened by inputredirection
160 until the end is reached or the loop is broken. For each line
161 read, the command list is executed with the line's contents as‐
162 signed to the REPLY variable and the line's fields split into
163 the positional parameters (see Field Splitting and Positional
164 Parameters below). Within the list, standard input is redi‐
165 rected to /dev/null. If the posix compatibility shell option is
166 on, this loop type is disabled and inputredirection is processed
167 like a lone redirection in any other context.
168 ((expression))
170 The expression is evaluated using the rules for arithmetic eval‐
171 uation described below. If the value of the arithmetic expres‐
172 sion is non-zero, the exit status is 0, otherwise the exit sta‐
173 tus is 1.
174 (list)
176 Execute list in a subshell (see Subshells below). Note, that if
177 two adjacent open parentheses are needed for nesting, a space
178 must be inserted to avoid evaluation as an arithmetic command as
179 described above.
180 { list;}
182 list is simply executed. Note that unlike the metacharacters (
183 and ), { and } are reserved words and must occur at the begin‐
184 ning of a line or after a ; in order to be recognized.
185 [[ expression ]]
187 Evaluates expression and returns a zero exit status when expres‐
188 sion is true. See Conditional Expressions below, for a descrip‐
189 tion of expression.
190 function varname { list ;}
192 varname () { list ;}
193 Define a function which is referenced by varname. A function
194 whose varname contains a . is called a discipline function and
195 the portion of the varname preceding the last . must refer to
196 an existing variable. The body of the function is the list of
197 commands between { and }. A function defined with the function
198 varname syntax can also be used as an argument to the . special
199 built-in command to get the equivalent behavior as if the var‐
200 name() syntax were used to define it. (See Functions below.)
201 namespace identifier { list ;}
203 Defines or uses the name space identifier and runs the commands
204 in list in this name space. (See Name Spaces below.)
205 & [ name [ arg... ] ]
207 Causes subsequent list commands terminated by & to be placed in
208 the background job pool name. If name is omitted a default un‐
209 named pool is used. Commands in a named background pool may be
210 executed remotely.
211 time [ pipeline ]
213 If pipeline is omitted the user and system time for the current
214 shell and completed child processes is printed on standard er‐
215 ror. Otherwise, pipeline is executed and the elapsed time as
216 well as the user and system time are printed on standard error.
217 The TIMEFORMAT variable may be set to a format string that spec‐
218 ifies how the timing information should be displayed. See Shell
219 Variables below for a description of the TIMEFORMAT variable.
220 The following reserved words are recognized as reserved only when they
222 are the first word of a command and are not quoted:
223 if then else elif fi case esac for while until do done { } function se‐
225 lect time [[ ]] !
226 Variable Assignments.
228 One or more variable assignments can start a simple command or can be
229 arguments to the typeset, enum, export, or readonly special built-in
230 commands as well as to other declaration commands created as types.
231 The syntax for an assignment is of the form:
232 varname=word
234 varname[word]=word
235 No space is permitted between varname and the = or between = and
236 word.
237 varname=(assign_list)
239 No space is permitted between varname and the =. The variable
240 varname is unset before the assignment. An assign_list can be
241 one of the following:
242 word ...
243 Indexed array assignment.
244 [word]=word ...
245 Associative array assignment. If preceded by
246 typeset -a this will create an indexed array in‐
247 stead.
248 assignment ...
249 Compound variable assignment. This creates a
250 compound variable varname with subvariables of
251 the form varname.name, where name is the name
252 portion of assignment. The value of varname will
253 contain all the assignment elements. Additional
254 assignments made to subvariables of varname will
255 also be displayed as part of the value of var‐
256 name. If no assignments are specified, varname
257 will be a compound variable allowing subsequence
258 child elements to be defined.
259 typeset [options] assignment ...
260 Nested variable assignment. Multiple assignments
261 can be specified by separating each of them with
262 a ;. The previous value is unset before the as‐
263 signment. Other declaration commands such as
264 readonly, enum, and other declaration commands
265 can be used in place of typeset.
266 . filename
267 Include the assignment commands contained in
268 filename.
269 In addition, a += can be used in place of the = to signify adding to or
271 appending to the previous value. When += is applied to an arithmetic
272 type, word is evaluated as an arithmetic expression and added to the
273 current value. When applied to a string variable, the value defined by
274 word is appended to the value. For compound assignments, the previous
275 value is not unset and the new values are appended to the current ones
276 provided that the types are compatible.
277 The right hand side of a variable assignment undergoes all the expan‐
279 sion listed below except word splitting, brace expansion, and pathname
280 expansion. When the left hand side is an assignment is a compound
281 variable and the right hand is the name of a compound variable, the
282 compound variable on the right will be copied or appended to the com‐
283 pound variable on the left.
284 Comments.
286 A word beginning with # causes that word and all the following charac‐
287 ters up to a new-line to be ignored.
288 Aliasing.
290 The first word of each command is replaced by the text of an alias if
291 an alias for this word has been defined. An alias name consists of any
292 number of characters excluding metacharacters, quoting characters, file
293 expansion characters, parameter expansion and command substitution
294 characters, the characters / and =. The replacement string can contain
295 any valid shell script including the metacharacters listed above. The
296 first word of each command in the replaced text, other than any that
297 are in the process of being replaced, will be tested for aliases. If
298 the last character of the alias value is a blank then the word follow‐
299 ing the alias will also be checked for alias substitution. Aliases can
300 be used to redefine built-in commands but cannot be used to redefine
301 the reserved words listed above. Aliases can be created and listed
302 with the alias command and can be removed with the unalias command.
303 Aliasing is performed when scripts are read, not while they are exe‐
305 cuted. Therefore, for an alias to take effect, the alias definition
306 command has to be executed before the command which references the
307 alias is read.
308 The following aliases are automatically preset when the shell is in‐
310 voked as an interactive shell. Preset aliases can be unset or rede‐
311 fined.
312 history=′hist -l′
313 r=′hist -s′
314 Tilde Expansion.
316 After alias substitution is performed, each word is checked to see if
317 it begins with an unquoted ∼. For tilde expansion, word also refers to
318 the word portion of parameter expansion (see Parameter Expansion be‐
319 low). If a word is preceded by a tilde, then it is checked up to a /
320 to see if it matches a user name in the password database (see getpw‐
321 name(3)). If a match is found, the ∼ and the matched login name are
322 replaced by the login directory of the matched user. If no match is
323 found, the original text is left unchanged. A ∼ by itself, or in front
324 of a /, is replaced by $HOME, unless the HOME variable is unset, in
325 which case the current user's home directory as configured in the oper‐
326 ating system is used. A ∼ followed by a + or - is replaced by $PWD or
327 $OLDPWD respectively.
328 In addition, when expanding a variable assignment (see Variable Assign‐
330 ments above), tilde expansion is attempted when the value of the as‐
331 signment begins with a ∼, and when a ∼ appears after a :. A : also
332 terminates a user name following a ∼.
333 The tilde expansion mechanism may be extended or modified by defining
335 one of the discipline functions .sh.tilde.set or .sh.tilde.get (see
336 Functions and Discipline Functions below). If either exists, then upon
337 encountering a tilde word to expand, that function is called with the
338 tilde word assigned to either .sh.value (for the .sh.tilde.set func‐
339 tion) or .sh.tilde (for the .sh.tilde.get function). Performing tilde
340 expansion within a discipline function will not recursively call that
341 function, but default tilde expansion remains active, so literal tildes
342 should still be quoted where required. Either function may assign a
343 replacement string to .sh.value. If this value is non-empty and does
344 not start with a ∼, it replaces the default tilde expansion when the
345 function terminates. Otherwise, the tilde expansion is left unchanged.
346 Subshells.
348 A subshell is a separate execution environment that is a complete du‐
349 plicate of the current shell environment, except for two things: all
350 traps are reset to default except those for signals that are being ig‐
351 nored, and subshells cannot be interactive (i.e., they have no command
352 prompt). Changes made within a subshell do not affect the parent envi‐
353 ronment and are lost when the subshell exits.
354 Particular care should be taken not to confuse a subshell with a newly
356 invoked shell that is merely a child process of the current shell, and
357 which (unlike a subshell) starts from scratch in terms of variables and
358 functions and may be interactive. Beware of shell tutorials on the In‐
359 ternet that confuse these.
360 Subshells are not themselves invoked as commands. Instead, the follow‐
362 ing are automatically run in or from a subshell:
363 • any command or group of commands enclosed in parentheses;
365 • command substitutions of the first and third form (see Com‐
367 mand Substitution below);
368 • process substitutions (see Process Substitution below);
370 • all elements of a pipeline except the last;
372 • any command executed asynchronously (i.e., in a background
374 process).
375 Creating processes is expensive, so as a performance optimization, a
377 subshell of a non-interactive shell may share the process of its parent
378 environment. Such a subshell is known as a virtual subshell. Subshells
379 are virtual unless or until something (such as asynchronous execution,
380 or an attempt to set a process limit using the ulimit built-in command,
381 or other implementation- or system-defined requirements) makes it nec‐
382 essary to fork it into a separate process. Barring any bugs in the
383 shell, virtual subshells should be indistinguishable from real sub‐
384 shells except by their execution speed and their process ID. See the
385 description of the .sh.pid variable below for more information.
386 Command Substitution.
388 The standard output from a command list enclosed in parentheses pre‐
389 ceded by a dollar sign ( $(list) ), or in a brace group preceded by a
390 dollar sign ( ${ list;} ), or in a pair of grave accents (``) may be
391 used as part or all of a word; trailing new-lines are removed. In the
392 second case, the { and } are treated as a reserved words so that { must
393 be followed by a blank and } must appear at the beginning of the line
394 or follow a ;. In the third (obsolete) form, the string between the
395 quotes is processed for special quoting characters before the command
396 is executed (see Quoting below). The command substitution $(cat file)
397 can be replaced by the equivalent but faster $(<file). The command
398 substitution $(n<#) will expand to the current byte offset for file de‐
399 scriptor n. Except for the second form, the command list is run in a
400 subshell so that no side effects are possible. For the second form,
401 the final } will be recognized as a reserved word after any token.
402 Arithmetic Expansion.
404 An arithmetic expression enclosed in double parentheses preceded by a
405 dollar sign ( $(()) ) is replaced by the value of the arithmetic ex‐
406 pression within the double parentheses.
407 Process Substitution.
409 Each command argument of the form <(list) or >(list) will run process
410 list asynchronously connected to some file in /dev/fd if this directory
411 exists, or else a fifo in a temporary directory. The name of this file
412 will become the argument to the command. If the form with > is se‐
413 lected then writing on this file will provide input for list. If < is
414 used, then the file passed as an argument will contain the output of
415 the list process. For example,
416 paste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1)
418 >(process2)
419 cuts fields 1 and 3 from the files file1 and file2 respectively, pastes
421 the results together, and sends it to the processes process1 and
422 process2, as well as putting it onto the standard output. Note that
423 the file, which is passed as an argument to the command, is a UNIX
424 pipe(2) so programs that expect to lseek(2) on the file will not work.
425 Process substitution of the form <(list) can also be used with the <
427 redirection operator which causes the output of list to be standard in‐
428 put or the input for whatever file descriptor is specified.
429 Parameter Expansion.
431 A parameter is a variable, one or more digits, or any of the characters
432 *, @, #, ?, -, $, and !. A variable is denoted by a vname. To create
433 a variable whose vname contains a ., a variable whose vname consists of
434 everything before the last . must already exist. A variable has a
435 value and zero or more attributes. Variables can be assigned values
436 and attributes by using the typeset special built-in command. The at‐
437 tributes supported by the shell are described later with the typeset
438 special built-in command. Exported variables pass their attributes to
439 the environment so that a newly invoked ksh that is a child or exec'd
440 process of the current shell will automatically import them, unless the
441 posix shell option is on.
442 The shell supports both indexed and associative arrays. An element of
444 an array variable is referenced by a subscript. A subscript for an in‐
445 dexed array is denoted by an arithmetic expression (see Arithmetic
446 Evaluation below) between a [ and a ]. To assign values to an indexed
447 array, use vname=(value ...) or set -A vname value ... . The value of
448 all non-negative subscripts must be in the range of 0 through
449 4,194,303. A negative subscript is treated as an offset from the maxi‐
450 mum current index +1 so that -1 refers to the last element. Indexed
451 arrays can be declared with the -a option to typeset. Indexed arrays
452 need not be declared. Any reference to a variable with a valid sub‐
453 script is legal and an array will be created if necessary.
454 An associative array is created with the -A option to typeset. A sub‐
456 script for an associative array is denoted by a string enclosed between
457 [ and ].
458 Referencing any array without a subscript is equivalent to referencing
460 the array with subscript 0.
461 The value of a variable may be assigned by writing:
463 vname=value [ vname=value ] ...
465 or
467 vname[subscript]=value [ vname[subscript]=value ] ...
469 Note that no space is allowed before or after the =.
471 Attributes assigned by the typeset special built-in command apply to
473 all elements of the array. An array element can be a simple variable,
474 a compound variable or an array variable. An element of an indexed ar‐
475 ray can be either an indexed array or an associative array. An element
476 of an associative array can also be either. To refer to an array ele‐
477 ment that is part of an array element, concatenate the subscript in
478 brackets. For example, to refer to the foobar element of an associa‐
479 tive array that is defined as the third element of the indexed array,
480 use ${vname[3][foobar]}
481 A nameref is a variable that is a reference to another variable. A
483 nameref is created with the -n attribute of typeset. The value of the
484 variable at the time of the typeset command becomes the variable that
485 will be referenced whenever the nameref variable is used. The name of
486 a nameref cannot contain a .. When a variable or function name con‐
487 tains a ., and the portion of the name up to the first . matches the
488 name of a nameref, the variable referred to is obtained by replacing
489 the nameref portion with the name of the variable referenced by the
490 nameref. If a nameref is used as the index of a for loop, a name ref‐
491 erence is established for each item in the list. A nameref provides a
492 convenient way to refer to the variable inside a function whose name is
493 passed as an argument to a function. For example, if the name of a
494 variable is passed as the first argument to a function, the command
495 typeset -n var=$1
497 inside the function causes references and assignments to var to be ref‐
499 erences and assignments to the variable whose name has been passed to
500 the function.
501 If any of the floating point attributes, -E, -F, or -X, or the integer
503 attribute, -i, is set for vname, then the value is subject to arith‐
504 metic evaluation as described below.
505 Positional parameters, parameters denoted by a number, may be assigned
507 values with the set special built-in command. Parameter $0 is set from
508 argument zero when the shell is invoked.
509 The character $ is used to introduce substitutable parameters.
511 ${parameter}
513 The shell reads all the characters from ${ to the matching } as
514 part of the same word even if it contains braces or metacharac‐
515 ters. The value, if any, of the parameter is substituted. The
516 braces are required when parameter is followed by a letter,
517 digit, or underscore that is not to be interpreted as part of
518 its name, when the variable name contains a .. The braces are
519 also required when a variable is subscripted unless it is part
520 of an Arithmetic Expression or a Conditional Expression. If pa‐
521 rameter is one or more digits then it is a positional parameter.
522 A positional parameter of more than one digit must be enclosed
523 in braces. If parameter is * or @, then all the positional pa‐
524 rameters, starting with $1, are substituted (separated by a
525 field separator character). If an array vname with last sub‐
526 script * @, or for indexed arrays of the form sub1 .. sub2. is
527 used, then the value for each of the elements between sub1 and
528 sub2 inclusive (or all elements for * and @) is substituted,
529 separated by the first character of the value of IFS.
530 ${#parameter}
532 If parameter is * or @, the number of positional parameters is
533 substituted. Otherwise, the length of the value of the parame‐
534 ter is substituted.
535 ${#vname[*]}
537 ${#vname[@]}
538 The number of elements in the array vname is substituted.
539 ${@vname}
541 Expands to the type name (See Type Variables below) or at‐
542 tributes of the variable referred to by vname.
543 ${!vname}
545 Expands to the name of the variable referred to by vname. This
546 will be vname except when vname is a name reference.
547 ${!vname[subscript]}
549 Expands to name of the subscript unless subscript is *, @. or
550 of the form sub1 .. sub2. When subscript is *, the list of ar‐
551 ray subscripts for vname is generated. For a variable that is
552 not an array, the value is 0 if the variable is set. Otherwise
553 it is the empty string. When subscript is @, same as above, ex‐
554 cept that when used in double quotes, each array subscript
555 yields a separate argument. When subscript is of the form sub1
556 .. sub2 it expands to the list of subscripts between sub1 and
557 sub2 inclusive using the same quoting rules as @.
558 ${!prefix@}
560 ${!prefix*}
561 These both expand to the names of the variables whose names be‐
562 gin with prefix. The expansions otherwise work like $@ and $*,
563 respectively (see under Quoting below).
564 ${parameter:-word}
566 If parameter is set and has a non-empty value, then substitute
567 its value; otherwise substitute word.
568 ${parameter:=word}
570 If parameter is not set or has the empty string value, then set
571 it to word; the value of the parameter is then substituted. Po‐
572 sitional parameters may not be assigned to in this way.
573 ${parameter:?word}
575 If parameter is set and has a non-empty value, then substitute
576 its value; otherwise, print word and exit from the shell (if not
577 interactive). If word is omitted then a standard message is
578 printed.
579 ${parameter:+word}
581 If parameter is set and has a non-empty value then substitute
582 word; otherwise substitute the empty string.
583 In the above, word is not evaluated unless it is to be used as the sub‐
585 stituted string, so that, in the following example, pwd is executed
586 only if d is not set or has the empty string value:
587 print ${d:-$(pwd)}
589 If the colon (:) is omitted from the above expressions, then the shell
591 only checks whether parameter is set or not.
592 ${parameter:offset:length}
594 ${parameter:offset}
595 Expands to the portion of the value of parameter starting at the
596 character (counting from 0) determined by expanding offset as an
597 arithmetic expression and consisting of the number of characters
598 determined by the arithmetic expression defined by length. In
599 the second form, the remainder of the value is used. If A nega‐
600 tive offset counts backwards from the end of parameter. Note
601 that one or more blanks is required in front of a minus sign to
602 prevent the shell from interpreting the operator as :-. If pa‐
603 rameter is * or @, or is an array name indexed by * or @, then
604 offset and length refer to the array index and number of ele‐
605 ments respectively. A negative offset is taken relative to one
606 greater than the highest subscript for indexed arrays. The or‐
607 der for associative arrays is unspecified.
608 ${parameter#pattern}
610 ${parameter##pattern}
611 If the shell pattern matches the beginning of the value of pa‐
612 rameter, then the value of this expansion is the value of the
613 parameter with the matched portion deleted; otherwise the value
614 of this parameter is substituted. In the first form the small‐
615 est matching pattern is deleted and in the second form the
616 largest matching pattern is deleted. When parameter is @, *, or
617 an array variable with subscript @ or *, the substring operation
618 is applied to each element in turn.
619 ${parameter%pattern}
621 ${parameter%%pattern}
622 If the shell pattern matches the end of the value of parameter,
623 then the value of this expansion is the value of the parameter
624 with the matched part deleted; otherwise substitute the value of
625 parameter. In the first form the smallest matching pattern is
626 deleted and in the second form the largest matching pattern is
627 deleted. When parameter is @, *, or an array variable with sub‐
628 script @ or *, the substring operation is applied to each ele‐
629 ment in turn.
630 ${parameter/pattern/string}
632 ${parameter//pattern/string}
633 ${parameter/#pattern/string}
634 ${parameter/%pattern/string}
635 Expands parameter and replaces the longest match of pattern with
636 the given string. Each occurrence of \n in string is replaced
637 by the portion of parameter that matches the n-th subpattern.
638 In the first form, only the first occurrence of pattern is re‐
639 placed. In the second form, each match for pattern is replaced
640 by the given string. The third form restricts the pattern match
641 to the beginning of the string while the fourth form restricts
642 the pattern match to the end of the string. When string is
643 empty, the pattern will be deleted and the / in front of string
644 may be omitted. When parameter is @, *, or an array variable
645 with subscript @ or *, the substitution operation is applied to
646 each element in turn. In this case, the string portion of word
647 will be re-evaluated for each element.
648 Shell Variables.
650 The following parameters are automatically set by the shell:
651 # The number of positional parameters in decimal.
652 - Options supplied to the shell on invocation or by the set
654 command.
655 ? The exit status returned by the last executed command.
657 Its meaning depends on the command or function that de‐
658 fines it, but there are conventions that other commands
659 often depend on: zero typically means 'success' or
660 'true', one typically means 'non-success' or 'false', and
661 a value greater than one typically indicates some kind of
662 error. Only the 8 least significant bits of $? (values 0
663 to 255) are preserved when the exit status is passed on
664 to a parent process, but within the same (sub)shell envi‐
665 ronment, it is a signed integer value with a range of
666 possible values as shown by the commands getconf INT_MIN
667 and getconf INT_MAX. Shell functions that run in the cur‐
668 rent environment may return status values in this range.
669 $ The process ID of the main shell process. Note that this
671 value will not change in a subshell, even if the subshell
672 runs in a different process. See also .sh.pid.
673 _ Initially, the value of _ is an absolute pathname of the
675 shell or script being executed as passed in the environ‐
676 ment. Subsequently it is assigned the last argument of
677 the previous command. This parameter is not set for com‐
678 mands which are asynchronous. This parameter is also
679 used to hold the name of the matching MAIL file when
680 checking for mail. While defining a compound variable or
681 a type, _ is initialized as a reference to the compound
682 variable or type. When a discipline function is invoked,
683 _ is initialized as a reference to the variable associ‐
684 ated with the call to this function. Finally when _ is
685 used as the name of the first variable of a type defini‐
686 tion, the new type is derived from the type of the first
687 variable. (See Type Variables below.)
688 ! The process ID or the pool name and job number of the
690 last background command invoked or the most recent job
691 put in the background with the bg built-in command.
692 Background jobs started in a named pool will be in the
693 form pool.number where pool is the pool name and number
694 is the job number within that pool.
695 .sh.command
697 When processing a DEBUG trap, this variable contains the
698 current command line that is about to run. The value is
699 in the same format as the output generated by the xtrace
700 option (minus the preceding PS4 prompt).
701 .sh.edchar
703 This variable contains the value of the keyboard charac‐
704 ter (or sequence of characters if the first character is
705 an ESC, ASCII 033) that has been entered when processing
706 a KEYBD trap (see Key Bindings below). If the value is
707 changed as part of the trap action, then the new value
708 replaces the key (or key sequence) that caused the trap.
709 .sh.edcol
711 The character position of the cursor at the time of the
712 most recent KEYBD trap.
713 .sh.edmode
715 Upon executing a KEYBD trap action, the value of this
716 variable is set to the ESC control character if the shell
717 is in vi insert mode (See Vi Editing Mode below), or to
718 the empty string value otherwise.
719 .sh.edtext
721 The characters in the input buffer at the time of the
722 most recent KEYBD trap. The variable is unset when not
723 processing a KEYBD trap.
724 .sh.file
726 The pathname of the file that contains the current com‐
727 mand.
728 .sh.fun
730 The name of the current function that is being executed.
731 .sh.level
733 Set to the current call depth of functions and dot
734 scripts. Normally, this variable is read-only, but while
735 executing a DEBUG trap, its value may be changed to
736 switch the current function scope to that of the speci‐
737 fied level for the duration of the trap run, making it
738 possible to access a parent scope for debugging purposes.
739 When trap execution ends, the variable and the scope are
740 restored. It is an error to assign a value lower than 0
741 (the global scope) or higher than the current call depth.
742 .sh.lineno
744 Set during a DEBUG trap to the line number for the caller
745 of each function.
746 .sh.match
748 An indexed array which stores the most recent match and
749 subpattern matches after conditional pattern matches that
750 match and after variables expansions using the operators
751 #, %, or /. The 0-th element stores the complete match
752 and the i-th. element stores the i-th submatch. For //,
753 the array is two-dimensional, with the first subscript
754 indicating the most recent match and subpattern match,
755 and the second subscript indicating which match with 0
756 representing the first match. The .sh.match variable be‐
757 comes unset when the variable that has expanded is as‐
758 signed a new value.
759 .sh.math
761 Used for defining arithmetic functions (see Arithmetic
762 Evaluation below) and stores the list of user defined
763 arithmetic functions.
764 .sh.name
766 Set to the name of the variable at the time that a disci‐
767 pline function is invoked.
768 .sh.subscript
770 Set to the name subscript of the variable at the time
771 that a discipline function is invoked.
772 .sh.subshell
774 The current depth for subshells and command substitution.
775 .sh.pid
777 Set to the process ID of the current shell process. Un‐
778 like $$, this is updated in a subshell when it forks into
779 a new process. Note that a virtual subshell may have to
780 fork mid-execution due to various system- and implementa‐
781 tion-dependent requirements, so the value should not be
782 counted on to remain the same from one command to the
783 next. If a persistent process ID is required for a sub‐
784 shell, it must be ensured it is running in its own
785 process first. Any attempt to set a process limit using
786 the ulimit built-in command, such as ulimit -t unlimited
787 2>/dev/null, is a reliable way to make a subshell fork if
788 it hasn't already.
789 .sh.ppid
791 Set to the process ID of the parent of the current shell
792 process. Unlike $PPID, this is updated in a subshell
793 when it forks into a new process. The same note as for
794 .sh.pid applies.
795 .sh.value
797 Set to the value of the variable at the time that the set
798 or append discipline function is invoked. When a user
799 defined arithmetic function is invoked, the value of
800 .sh.value is saved and .sh.value is set to long double
801 precision floating point. .sh.value is restored when the
802 function returns.
803 .sh.version
805 Set to a value that identifies the version of this shell.
806 COLUMNS
808 Width of the terminal window in character positions. Up‐
809 dated automatically at initialization and on receiving a
810 SIGWINCH signal. The shell uses the value to define the
811 width of the edit window for the shell edit modes and for
812 printing select lists.
813 KSH_VERSION
815 A name reference to .sh.version.
816 LINENO The current line number within the script or function be‐
818 ing executed.
819 LINES Height of the terminal window in lines. Updated automat‐
821 ically at initialization and on receiving a SIGWINCH sig‐
822 nal. The shell uses the value to determine the column
823 length for printing select lists: they are printed verti‐
824 cally until about two thirds of LINES lines are filled.
825 OLDPWD The previous working directory set by the cd command.
827 OPTARG The value of the last option argument processed by the
829 getopts built-in command.
830 OPTIND The index of the last option argument processed by the
832 getopts built-in command.
833 PPID The process ID of the parent of the main shell process.
835 Note that this value will not change in a subshell, even
836 if the subshell runs in a different process. See also
837 .sh.ppid.
838 PWD The present working directory set by the cd command.
840 RANDOM Each time this variable is referenced, a random integer,
842 uniformly distributed between 0 and 32767, is generated.
843 The sequence of random numbers can be initialized by as‐
844 signing a numeric value to RANDOM.
845 REPLY This variable is set by the select statement and by the
847 read built-in command when no arguments are supplied.
848 SECONDS
850 Each time this variable is referenced, the number of sec‐
851 onds since shell invocation is returned. If this vari‐
852 able is assigned a value, then the value returned upon
853 reference will be the value that was assigned plus the
854 number of seconds since the assignment.
855 SHLVL An integer variable that is incremented and exported each
857 time the shell is invoked. If SHLVL is not in the envi‐
858 ronment when the shell is invoked, it is set to 1.
859 The following variables are used by the shell:
861 CDPATH The search path for the cd command.
862 EDITOR If the VISUAL variable is not set, the value of this
864 variable will be checked for certain patterns and the
865 corresponding editing option will be turned on as de‐
866 scribed with VISUAL below.
867 ENV If this variable is set, then parameter expansion, com‐
869 mand substitution, and arithmetic expansion are performed
870 on the value to generate the pathname of the script that
871 will be executed when the shell is invoked interactively
872 (see Invocation below). This file is typically used for
873 alias and function definitions. The default value is
874 $HOME/.kshrc. On systems that support a system wide
875 /etc/ksh.kshrc initialization file, if the filename gen‐
876 erated by the expansion of ENV begins with /./ or ././
877 the system wide initialization file will not be executed.
878 FCEDIT Obsolete name for the default editor name for the hist
880 command. FCEDIT is not used when HISTEDIT is set.
881 FIGNORE
883 A pattern that defines the set of filenames that will be
884 ignored when performing filename matching.
885 FPATH The search path for function definitions. The directo‐
887 ries in this path are searched for a file with the same
888 name as the function or command when a function with the
889 -u attribute is referenced and when a command is not
890 found. If an executable file with the name of that com‐
891 mand is found, then it is read and executed in the cur‐
892 rent environment. Unlike PATH, the current directory
893 must be represented explicitly by . rather than by adja‐
894 cent : characters or a beginning or ending :.
895 histchars
897 This variable can be used to specify up to three ASCII
898 characters that control history expansion (see History
899 Expansion below). The first (default: !) signals the
900 start of a history expansion. The second (default: ^) is
901 used for short-form substitutions. The third (default:
902 #), when found as the first character of a word, causes
903 history expansion to be skipped for the rest of the words
904 on the line. Multi-byte characters (e.g. UTF-8) are not
905 supported and produce undefined results.
906 HISTCMD
908 Number of the current command in the history file.
909 HISTEDIT
911 Name for the default editor name for the hist command.
912 HISTFILE
914 If this variable is set when the shell is invoked, then
915 the value is the pathname of the file that will be used
916 to store the command history (see Command Re-entry be‐
917 low).
918 HISTSIZE
920 If this variable is set when the shell is invoked, then
921 the number of previously entered commands that are acces‐
922 sible by this shell will be greater than or equal to this
923 number. The default is 512.
924 HOME The default argument (home directory) for the cd command.
926 IFS Internal field separators, normally space, tab, and new-
928 line that are used to separate the results of command
929 substitution or parameter expansion and to separate
930 fields with the built-in command read. The first charac‐
931 ter of the IFS variable is used to separate arguments for
932 the "$*" expansion (see Quoting below). Each single oc‐
933 currence of an IFS character in the string to be split
934 that is not in the isspace character class, and any adja‐
935 cent characters in IFS that are in the isspace character
936 class, delimit a field. One or more characters in IFS
937 that belong to the isspace character class delimit a
938 field. In addition, if the same isspace character ap‐
939 pears consecutively inside IFS and the posix shell option
940 is not on, this character is treated as if it were not in
941 the isspace class - for example, if IFS consists of two
942 tab characters, then two adjacent tab characters delimit
943 an empty field.
944 JOBMAX This variable defines the maximum number running back‐
946 ground jobs that can run at a time. When this limit is
947 reached, the shell will wait for a job to complete before
948 starting a new job.
949 LANG This variable determines the locale category for any cat‐
951 egory not specifically selected with a variable starting
952 with LC_ or LANG.
953 LC_ALL This variable overrides the value of the LANG variable
955 and any other LC_ variable.
956 LC_COLLATE
958 This variable determines the locale category for charac‐
959 ter collation information.
960 LC_CTYPE
962 This variable determines the locale category for charac‐
963 ter handling functions. It determines the character
964 classes for pattern matching (see Pathname Expansion be‐
965 low).
966 LC_NUMERIC
968 This variable determines the locale category for the dec‐
969 imal point character.
970 MAIL If this variable is set to the name of a mail file and
972 the MAILPATH variable is not set, then the shell informs
973 the user of arrival of mail in the specified file.
974 MAILCHECK
976 This variable specifies how often (in seconds) the shell
977 will check for changes in the modification time of any of
978 the files specified by the MAILPATH or MAIL variables.
979 The default value is 600 seconds. When the time has
980 elapsed the shell will check before issuing the next
981 prompt.
982 MAILPATH
984 A colon ( : ) separated list of file names. If this
985 variable is set, then the shell informs the user of any
986 modifications to the specified files that have occurred
987 within the last MAILCHECK seconds. Each file name can be
988 followed by a ? and a message that will be printed. The
989 message will undergo parameter expansion, command substi‐
990 tution, and arithmetic expansion with the variable $_ de‐
991 fined as the name of the file that has changed. The de‐
992 fault message is you have mail in $_.
993 PATH The search path for commands (see Execution below). The
995 user may not change PATH if executing under rksh (except
996 in .profile).
997 PS1 Every time a new command line is started on an interac‐
999 tive shell, the value of this variable is expanded to re‐
1000 solve backslash escaping, parameter expansion, command
1001 substitution, and arithmetic expansion. The result de‐
1002 fines the primary prompt string for that command line.
1003 The default is ``$ ''. The character ! in the primary
1004 prompt string is replaced by the command number (see Com‐
1005 mand Re-entry below). Two successive occurrences of !
1006 will produce a single ! when the prompt string is
1007 printed. Note that any terminal escape sequences used in
1008 the PS1 prompt thus need every instance of ! in them to
1009 be changed to !!.
1010 PS2 Secondary prompt string, by default ``> ''.
1012 PS3 Selection prompt string used within a select loop, by de‐
1014 fault ``#? ''.
1015 PS4 The value of this variable is expanded for parameter
1017 evaluation, command substitution, and arithmetic expan‐
1018 sion and precedes each line of an execution trace. By
1019 default, PS4 is ``+ ''. In addition when PS4 is unset,
1020 the execution trace prompt is also ``+ ''.
1021 SHELL The pathname of the shell is kept in the environment. At
1023 invocation, if the basename of this variable is rsh,
1024 rksh, or krsh, then the shell becomes restricted.
1025 TIMEFORMAT
1027 The value of this parameter is used as a format string
1028 specifying how the timing information for pipelines pre‐
1029 fixed with the time reserved word should be displayed.
1030 The % character introduces a format sequence that is ex‐
1031 panded to a time value or other information. The format
1032 sequences and their meanings are as follows.
1033 %% A literal %.
1034 %[p][l]R The elapsed time in seconds.
1035 %[p][l]U The number of CPU seconds spent in user mode.
1036 %[p][l]S The number of CPU seconds spent in system mode.
1037 %P The CPU percentage, computed as (U + S) / R.
1038 The brackets denote optional portions. The optional p is
1040 a digit specifying the precision, the number of frac‐
1041 tional digits after a decimal point. A value of 0 causes
1042 no decimal point or fraction to be output. At most three
1043 places after the decimal point can be displayed; values
1044 of p greater than 3 are treated as 3. If p is not speci‐
1045 fied, the value 3 is used.
1046 The optional l specifies a longer format, including hours
1048 if greater than zero, minutes, and seconds of the form
1049 HHhMMmSS.FFs. The value of p determines whether or not
1050 the fraction is included. Seconds are zero-padded unless
1051 the posix shell option is on.
1052 All other characters are output without change and a
1054 trailing newline is added. If the variable is unset, the
1055 default value, $'\nreal\t%2lR\nuser\t%2lU\nsys\t%2lS', is
1056 used. If the value is empty, no timing information is
1057 displayed.
1058 TMOUT Terminal read timeout. If set to a value greater than
1060 zero, the read built-in command and the select compound
1061 command time out after TMOUT seconds when input is from a
1062 terminal. An interactive shell will issue a warning and
1063 allow for an extra 60 second timeout grace period before
1064 terminating if a line is not entered within the pre‐
1065 scribed number of seconds while reading from a terminal.
1066 (Note that the shell can be compiled with a maximum bound
1067 for this value which cannot be exceeded.)
1068 VISUAL The value of this variable is scanned when the shell is
1070 invoked and whenever its value is changed; if it is found
1071 to match certain patterns, the corresponding line editor
1072 (see In-line Editing Options below) is activated. If it
1073 matches the pattern *[Vv][Ii]*, the vi option is turned
1074 on; else if it matches the pattern *gmacs*, the gmacs op‐
1075 tion is turned on; else if it matches the pattern *macs*,
1076 the emacs option is turned on. If none of the patterns
1077 match, emacs is turned on by default upon initializing an
1078 interactive shell. If the value is changed by assignment
1079 and none of the patterns match, no options are changed.
1080 The value of VISUAL overrides the value of EDITOR.
1081 The shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK,
1083 FCEDIT, TMOUT and IFS, while HOME, SHELL, ENV, histchars, and MAIL are
1084 not set at all by the shell (although HOME is set by login(1)). On
1085 some systems MAIL and SHELL are also set by login(1).
1086 Field Splitting.
1088 After parameter expansion and command substitution, the results of sub‐
1089 stitutions are scanned for the field separator characters (those found
1090 in IFS) and split into distinct fields where such characters are found.
1091 Explicit empty fields ("" or ′′) are retained. Implicit empty fields
1092 (those resulting from parameters that are unset or have empty string
1093 values or from command substitutions yielding the empty string, and
1094 that are not quoted with "") are removed.
1095 Brace Expansion.
1097 If the braceexpand (-B) option is set then each of the fields resulting
1098 from IFS are checked to see if they contain one or more of the brace
1099 patterns {*,*}, {l1..l2} , {n1..n2} , {n1..n2% fmt} , {n1..n2 ..n3} ,
1100 or {n1..n2 ..n3%fmt} , where * represents any character, l1,l2 are let‐
1101 ters and n1,n2,n3 are signed numbers and fmt is a format specified as
1102 used by printf. In each case, fields are created by prepending the
1103 characters before the { and appending the characters after the } to
1104 each of the strings generated by the characters between the { and }.
1105 The resulting fields are checked to see if they have any brace pat‐
1106 terns.
1107 In the first form, a field is created for each string between { and ,,
1109 between , and ,, and between , and }. The string represented by * can
1110 contain embedded matching { and } without quoting. Otherwise, each {
1111 and } with * must be quoted.
1112 In the seconds form, l1 and l2 must both be either upper case or both
1114 be lower case characters in the C locale. In this case a field is cre‐
1115 ated for each character from l1 through l2.
1116 In the remaining forms, a field is created for each number starting at
1118 n1 and continuing until it reaches n2 incrementing n1 by n3. The cases
1119 where n3 is not specified behave as if n3 where 1 if n1<=n2 and -1 oth‐
1120 erwise. If forms which specify %fmt any format flags, widths and pre‐
1121 cisions can be specified and fmt can end in any of the specifiers
1122 cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to the 8
1123 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx, z04bx and z04cx.
1124 Pathname Expansion.
1126 This is also known as globbing or sometimes filename generation. Fol‐
1127 lowing splitting, each field is scanned for the characters *, ?, (, and
1128 [ unless the -f option has been set. If one of these characters ap‐
1129 pears, then the word is regarded as a pattern. Each file name compo‐
1130 nent that contains any pattern character is replaced with a lexico‐
1131 graphically sorted set of names that matches the pattern from that di‐
1132 rectory. If no file name is found that matches the pattern, then that
1133 component of the filename is left unchanged unless the pattern is pre‐
1134 fixed with ∼(N), in which case it is removed as described below. The
1135 special traversal names . and .. are never matched. If FIGNORE is
1136 set, then each file name component that matches the pattern defined by
1137 the value of FIGNORE is ignored when generating the matching filenames.
1138 If FIGNORE is not set, the character . at the start of each file name
1139 component will be ignored unless the first character of the pattern
1140 corresponding to this component is the character . itself. Note that,
1141 for uses of pattern matching other than pathname expansion, the / and .
1142 are not treated specially.
1143 * Matches any string, including the empty string. When
1145 used for filename expansion, if the globstar option is
1146 on, an isolated pattern of two adjacent *s will match all
1147 files and zero or more directories and subdirectories.
1148 If followed by a / then only directories and subdirecto‐
1149 ries will match.
1150 ? Matches any single character.
1151 [...] Matches any one of the enclosed characters. A pair of
1152 characters separated by - matches any character lexically
1153 between the pair, inclusive. If the first character fol‐
1154 lowing the opening [ is a ! or ^, then any character not
1155 enclosed is matched. A - can be included in the charac‐
1156 ter set by putting it as the first or last character.
1157 Within [ and ], character classes can be specified with
1158 the syntax [:class:], where class is one of the following
1159 classes defined in the ANSI C standard (note that word is
1160 equivalent to alnum plus the character _):
1161 alnum alpha blank cntrl digit graph lower print punct
1162 space upper word xdigit
1163 Within [ and ], an equivalence class can be specified
1164 with the syntax [=c=] which matches all characters with
1165 the same primary collation weight (as defined by the cur‐
1166 rent locale) as the character c. Within [ and ], [.sym‐
1167 bol.] matches the collating symbol symbol.
1168 A pattern-list is a list of one or more patterns separated from each
1170 other with a & or |. A & signifies that all patterns must be matched
1171 whereas | requires that only one pattern be matched. Composite pat‐
1172 terns can be formed with one or more of the following subpatterns:
1173 ?(pattern-list)
1174 Optionally matches any one of the given patterns.
1175 *(pattern-list)
1176 Matches zero or more occurrences of the given patterns.
1177 +(pattern-list)
1178 Matches one or more occurrences of the given patterns.
1179 {n}(pattern-list)
1180 Matches n occurrences of the given patterns.
1181 {m,n}(pattern-list)
1182 Matches from m to n occurrences of the given patterns.
1183 If m is omitted, 0 will be used. If n is omitted, at
1184 least m occurrences will be matched.
1185 @(pattern-list)
1186 Matches exactly one of the given patterns.
1187 !(pattern-list)
1188 Matches anything except one of the given patterns.
1189 By default, each pattern or subpattern will match the longest string
1191 possible consistent with generating the longest overall match. If more
1192 than one match is possible, the one starting closest to the beginning
1193 of the string will be chosen. However, for each of the above compound
1194 patterns, a - can be inserted in front of the ( to cause the shortest
1195 match to the specified pattern-list to be used.
1196 When pattern-list is contained within parentheses, the backslash char‐
1198 acter \ is treated specially even when inside a character class. All
1199 ANSI C character escapes are recognized and match the specified charac‐
1200 ter. In addition, the following escape sequences are recognized:
1201 \d Matches any character in the digit class.
1202 \D Matches any character not in the digit class.
1203 \s Matches any character in the space class.
1204 \S Matches any character not in the space class.
1205 \w Matches any character in the word class.
1206 \W Matches any character not in the word class.
1207 A pattern of the form %(pattern-pair(s)) is a subpattern that can be
1209 used to match nested character expressions. Each pattern-pair is a
1210 two-character sequence that cannot contain & or |. The first pattern-
1211 pair specifies the starting and ending characters for the match. Each
1212 subsequent pattern-pair represents the beginning and ending characters
1213 of a nested group that will be skipped over when counting starting and
1214 ending character matches. The behavior is unspecified when the first
1215 character of a pattern-pair is alphanumeric, except for the following:
1216 D Causes the ending character to terminate the search for
1217 this pattern without finding a match.
1218 E Causes the ending character to be interpreted as an es‐
1219 cape character.
1220 L Causes the ending character to be interpreted as a quote
1221 character, causing all characters to be ignored when
1222 looking for a match.
1223 Q Causes the ending character to be interpreted as a quote
1224 character, causing all characters other than any escape
1225 character to be ignored when looking for a match.
1226 Thus, %({}Q"E\), matches characters starting at { until the matching }
1228 is found, not counting any { or } that is inside a double-quoted string
1229 or preceded by the escape character \. Without the {}, this pattern
1230 matches any C language string.
1231 Each subpattern in a composite pattern is numbered, starting at 1, by
1233 the location of the ( within the pattern. The sequence \n, where n is
1234 a single digit and \n comes after the nth subpattern, matches the same
1235 string as the subpattern itself.
1236 Finally, a pattern can contain subpatterns of the form ∼(options:pat‐
1238 tern-list), where either options or :pattern-list can be omitted. Un‐
1239 like the other compound patterns, these subpatterns are not counted in
1240 the numbered subpatterns. :pattern-list must be omitted for options F,
1241 G, N, and V below. If options is present, it can consist of one or
1242 more of the following:
1243 + Enable the following options. This is the default.
1244 - Disable the following options.
1245 E The remainder of the pattern uses extended regular ex‐
1246 pression syntax like the -E option of the grep(1) com‐
1247 mand.
1248 F The remainder of the pattern uses the fixed pattern syn‐
1249 tax of the -F option of the grep(1) command.
1250 G The remainder of the pattern uses basic regular expres‐
1251 sion syntax like the grep(1) command without options.
1252 K The remainder of the pattern uses shell pattern syntax.
1253 This is the default.
1254 N When it is the first letter and is used with pathname ex‐
1255 pansion, and no matches occur, the file pattern expands
1256 to the empty string instead of remaining unexpanded.
1257 Otherwise, it is ignored.
1258 X The remainder of the pattern uses augmented regular ex‐
1259 pression syntax like the -X option of the AT&T AST ver‐
1260 sion of the grep(1) command.
1261 P The remainder of the pattern uses perl(1) regular expres‐
1262 sion syntax. Not all perl regular expression syntax is
1263 currently implemented.
1264 V The remainder of the pattern uses System V regular ex‐
1265 pression syntax.
1266 i Always treat the match as case-insensitive, regardless of
1267 the globcasedetect shell option.
1268 g File the longest match (greedy). This is the default.
1269 l Left-anchor the pattern. This is the default for K style
1270 patterns.
1271 r Right-anchor the pattern. This is the default for K
1272 style patterns.
1273 If both options and :pattern-list are specified, then the options apply
1275 only to pattern-list. Otherwise, these options remain in effect until
1276 they are disabled by a subsequent ∼(...) or at the end of the subpat‐
1277 tern containing ∼(...).
1278 Quoting.
1280 Each of the metacharacters listed earlier (see Definitions above) has a
1281 special meaning to the shell and causes termination of a word unless
1282 quoted. A character may be quoted (i.e., made to stand for itself) by
1283 preceding it with a \. The pair \new-line is removed. All characters
1284 enclosed between a pair of single quote marks (′′) that is not preceded
1285 by a $ are quoted. A single quote cannot appear within the single
1286 quotes. A single quoted string preceded by an unquoted $ is processed
1287 as an ANSI C string except for the following:
1288 \0 Causes the remainder of the string to be ignored.
1289 \E Equivalent to the escape character (ASCII 033),
1290 \e Equivalent to the escape character (ASCII 033),
1291 \cx Expands to the character control-x.
1292 \C[.name.]
1293 Expands to the collating element name.
1294 Inside double quote marks (""), parameter and command substitution oc‐
1296 cur and \ quotes the characters \, `, ", and $. A $ in front of a dou‐
1297 ble quoted string will be ignored in the "C" or "POSIX" locale, and may
1298 cause the string to be replaced by a locale specific string otherwise.
1299 The meaning of $* and $@ is identical when not quoted or when used as a
1300 variable assignment value or as a file name. However, when used as a
1301 command argument, "$*" is equivalent to "$1d$2d...", where d is the
1302 first character of the IFS variable, whereas "$@" is equivalent to "$1"
1303 "$2" .... Inside grave quote marks (``), \ quotes the characters \, `,
1304 and $. If the grave quotes occur within double quotes, then \ also
1305 quotes the character ".
1306 The special meaning of reserved words or aliases can be removed by
1308 quoting any character of the reserved word. The recognition of func‐
1309 tion names or built-in command names listed below cannot be altered by
1310 quoting them.
1311 Arithmetic Evaluation.
1313 The shell performs arithmetic evaluation for arithmetic expansion, to
1314 evaluate an arithmetic command, to evaluate an indexed array subscript,
1315 and to evaluate arguments to the built-in commands shift and let as
1316 well as arguments to numeric format specifiers given to print -f and
1317 printf. Evaluations are performed using double precision floating
1318 point arithmetic or long double precision floating point for systems
1319 that provide this data type. Floating point constants follow the ANSI
1320 C programming language floating point conventions. The case-insensi‐
1321 tive floating point constants NaN and Inf can be used to represent "not
1322 a number" and infinity respectively, unless the posix shell option is
1323 on. Integer constants follow the ANSI C programming language integer
1324 constant conventions although only single byte character constants are
1325 recognized and character casts are not recognized. In addition con‐
1326 stants can be of the form [base#]n where base is a decimal number be‐
1327 tween two and sixty-four representing the arithmetic base and n is a
1328 number in that base. The digits above 9 are represented by the lower
1329 case letters, the upper case letters, @, and _ respectively. For bases
1330 less than or equal to 36, upper and lower case characters can be used
1331 interchangeably.
1332 An arithmetic expression uses the same syntax, precedence, and associa‐
1334 tivity of expression as the C language. All the C language operators
1335 that apply to floating point quantities can be used. In addition, the
1336 operator ** can be used for exponentiation. It has higher precedence
1337 than multiplication and is left associative. In addition, when the
1338 value of an arithmetic variable or subexpression can be represented as
1339 a long integer, all C language integer arithmetic operations can be
1340 performed. Variables can be referenced by name within an arithmetic
1341 expression without using the parameter expansion syntax. When a vari‐
1342 able is referenced, its value is evaluated as an arithmetic expression.
1343 Any of the following math library functions that are in the C math li‐
1345 brary can be used within an arithmetic expression:
1346 abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh
1348 erf erfc exp exp10 exp2 expm1 fabs fdim finite float floor fma fmax
1349 fmin fmod fpclass fpclassify hypot ilogb int isfinite isgreater is‐
1350 greaterequal isinf isinfinite isless islessequal islessgreater isnan
1351 isnormal issubnormal isunordered iszero j0 j1 jn ldexp lgamma log log10
1352 log1p log2 logb nearbyint nextafter nexttoward pow remainder rint round
1353 scalb scalbn signbit sin sinh sqrt tan tanh tgamma trunc y0 y1 yn
1354 In addition, arithmetic functions can be defined as shell functions
1356 with a variant of the function name syntax,
1357 function .sh.math.name ident ... { list ;}
1359 where name is the function name used in the arithmetic expres‐
1360 sion and each identifier, ident is a name reference to the long
1361 double precision floating point argument. The value of
1362 .sh.value when the function returns is the value of this func‐
1363 tion. User defined functions can take up to 3 arguments and
1364 override C math library functions.
1365 An internal representation of a variable as a double precision floating
1367 point can be specified with the -E [n], -F [n], or -X [n] option of the
1368 typeset special built-in command. The -E option causes the expansion
1369 of the value to be represented using scientific notation when it is ex‐
1370 panded. The optional option argument n defines the number of signifi‐
1371 cant figures. The -F option causes the expansion to be represented as
1372 a floating decimal number when it is expanded. The -X option causes
1373 the expansion to be represented using the %a format defined by ISO
1374 C-99. The optional option argument n defines the number of places af‐
1375 ter the decimal (or radix) point in this case.
1376 An internal integer representation of a variable can be specified with
1378 the -i [n] option of the typeset special built-in command. The op‐
1379 tional option argument n specifies an arithmetic base to be used when
1380 expanding the variable. If you do not specify an arithmetic base, base
1381 10 will be used.
1382 Arithmetic evaluation is performed on the value of each assignment to a
1384 variable with the -E, -F, -X, or -i attribute. Assigning a floating
1385 point number to a variable whose type is an integer causes the frac‐
1386 tional part to be truncated.
1387 Prompting.
1389 When used interactively, the shell prompts with the value of PS1 after
1390 expanding it for parameter expansion, command substitution, and arith‐
1391 metic expansion, before reading a command. In addition, each single !
1392 in the prompt is replaced by the command number. A !! is required to
1393 place ! in the prompt. If at any time a new-line is typed and further
1394 input is needed to complete a command, then the secondary prompt (i.e.,
1395 the value of PS2) is issued.
1396 Conditional Expressions.
1398 A conditional expression is used with the [[ compound command to test
1399 attributes of files and to compare strings. Field splitting and path‐
1400 name expansion are not performed on the words between [[ and ]]. Each
1401 expression can be constructed from one or more of the following unary
1402 or binary expressions:
1403 string Same as -n string below.
1404 -a file
1405 Same as -e below. This is obsolete.
1406 -b file
1407 True if file exists and is a block special file.
1408 -c file
1409 True if file exists and is a character special file.
1410 -d file
1411 True if file exists and is a directory.
1412 -e file
1413 True if file exists.
1414 -f file
1415 True if file exists and is an ordinary file.
1416 -g file
1417 True if file exists and it has its setgid bit set.
1418 -k file
1419 True if file exists and it has its sticky bit set.
1420 -n string
1421 True if length of string is non-zero.
1422 -o ?option
1423 True if option named option is a valid option name.
1424 -o option
1425 True if option named option is on.
1426 -p file
1427 True if file exists and is a fifo special file or a pipe.
1428 -r file
1429 True if file exists and is readable by current process.
1430 -s file
1431 True if file exists and has size greater than zero.
1432 -t fildes
1433 True if file descriptor number fildes is open and associ‐
1434 ated with a terminal device.
1435 -u file
1436 True if file exists and it has its setuid bit set.
1437 -v name
1438 True if variable name is a valid variable name and is
1439 set.
1440 -w file
1441 True if file exists and is writable by current process.
1442 -x file
1443 True if file exists and is executable by current process.
1444 If file exists and is a directory, then true if the cur‐
1445 rent process has permission to search in the directory.
1446 -z string
1447 True if length of string is zero.
1448 -L file
1449 True if file exists and is a symbolic link.
1450 -h file
1451 True if file exists and is a symbolic link.
1452 -N file
1453 True if file exists and the modification time is greater
1454 than the last access time.
1455 -O file
1456 True if file exists and is owned by the effective user ID
1457 of this process.
1458 -G file
1459 True if file exists and its group matches the effective
1460 group ID of this process.
1461 -R name
1462 True if variable name is a name reference.
1463 -S file
1464 True if file exists and is a socket.
1465 file1 -nt file2
1466 True if file1 exists and file2 does not, or file1 is
1467 newer than file2.
1468 file1 -ot file2
1469 True if file2 exists and file1 does not, or file1 is
1470 older than file2.
1471 file1 -ef file2
1472 True if file1 and file2 exist and refer to the same file.
1473 string == pattern
1474 True if string matches pattern. Any part of pattern can
1475 be quoted to cause it to be matched as a string. With a
1476 successful match to a pattern, the .sh.match array vari‐
1477 able will contain the match and subpattern matches.
1478 string = pattern
1479 Same as == above, but is obsolete.
1480 string != pattern
1481 True if string does not match pattern. When the string
1482 matches the pattern the .sh.match array variable will
1483 contain the match and subpattern matches.
1484 string =∼ ere
1485 True if string matches the pattern ∼(E)ere where ere is
1486 an extended regular expression.
1487 string1 < string2
1488 True if string1 comes before string2 based on ASCII value
1489 of their characters.
1490 string1 > string2
1491 True if string1 comes after string2 based on ASCII value
1492 of their characters.
1493 The following obsolete arithmetic comparisons are also permitted:
1495 exp1 -eq exp2
1496 True if exp1 is equal to exp2.
1497 exp1 -ne exp2
1498 True if exp1 is not equal to exp2.
1499 exp1 -lt exp2
1500 True if exp1 is less than exp2.
1501 exp1 -gt exp2
1502 True if exp1 is greater than exp2.
1503 exp1 -le exp2
1504 True if exp1 is less than or equal to exp2.
1505 exp1 -ge exp2
1506 True if exp1 is greater than or equal to exp2.
1507 In each of the above expressions, if file is of the form /dev/fd/n,
1509 where n is an integer, then the test is applied to the open file whose
1510 descriptor number is n.
1511 A compound expression can be constructed from these primitives by using
1513 any of the following, listed in decreasing order of precedence:
1514 (expression)
1515 True if expression is true. Used to group expressions.
1516 ! expression
1517 True if expression is false.
1518 expression1 && expression2
1519 True if expression1 and expression2 are both true.
1520 expression1 || expression2
1521 True if either expression1 or expression2 is true.
1522 Input/Output.
1524 Before a command is executed, its input and output may be redirected
1525 using a special notation interpreted by the shell. The following may
1526 appear anywhere in a simple-command or may precede or follow a command
1527 and are not passed on to the invoked command. Command substitution,
1528 parameter expansion, and arithmetic expansion occur before word or
1529 digit is used except as noted below. Pathname expansion occurs only if
1530 the shell is interactive and the pattern matches a single file. Field
1531 splitting is not performed.
1532 In each of the following redirections, if file is of the form
1534 /dev/sctp/host/port, /dev/tcp/host/port, or /dev/udp/host/port, where
1535 host is a hostname or host address, and port is a service given by name
1536 or an integer port number, then the redirection attempts to make a tcp,
1537 sctp or udp connection to the corresponding socket.
1538 No intervening space is allowed between the characters of redirection
1540 operators.
1541 <word Use file word as standard input (file descriptor 0).
1543 >word Use file word as standard output (file descriptor 1). If
1545 the file does not exist then it is created. If the file
1546 exists, and the noclobber option is on, this causes an
1547 error; otherwise, it is truncated to zero length.
1548 >|word Same as >, except that it overrides the noclobber option.
1550 >;word Write output to a temporary file. If the command com‐
1552 pletes successfully rename it to word, otherwise, delete
1553 the temporary file. >;word cannot be used with the exec
1554 and redirect built-ins.
1555 >>word Use file word as standard output. If the file exists,
1557 then output is appended to it (by first seeking to the
1558 end-of-file); otherwise, the file is created.
1559 <>word Open file word for reading and writing as standard out‐
1561 put. If the posix option is active, it defaults to stan‐
1562 dard input instead.
1563 <>;word The same as <>word except that if the command completes
1565 successfully, word is truncated to the offset at command
1566 completion. <>;word cannot be used with the exec and re‐
1567 direct built-ins.
1568 <<[-]word The shell input is read up to a line that is the same as
1570 word after any quoting has been removed, or to an end-of-
1571 file. No parameter expansion, command substitution,
1572 arithmetic expansion or pathname expansion is performed
1573 on word. The resulting document, called a here-document,
1574 becomes the standard input. If any character of word is
1575 quoted, then no interpretation is placed upon the charac‐
1576 ters of the document; otherwise, parameter expansion,
1577 command substitution, and arithmetic expansion occur,
1578 \new-line is ignored, and \ must be used to quote the
1579 characters \, $, `. If - is appended to <<, then all
1580 leading tabs are stripped from word and from the docu‐
1581 ment. If # is appended to <<, then leading spaces and
1582 tabs will be stripped off the first line of the document
1583 and up to an equivalent indentation will be stripped from
1584 the remaining lines and from word. A tab stop is assumed
1585 to occur at every 8 columns for the purposes of determin‐
1586 ing the indentation.
1587 <<<word A short form of here document in which word becomes the
1589 contents of the here-document after any parameter expan‐
1590 sion, command substitution, and arithmetic expansion oc‐
1591 cur.
1592 <&digit The standard input is duplicated from file descriptor
1594 digit (see dup(2)).
1595 >&digit The standard output is duplicated from file descriptor
1597 digit.
1598 <&digit- The file descriptor given by digit is moved to standard
1600 input.
1601 >&digit- The file descriptor given by digit is moved to standard
1603 output.
1604 <&- The standard input is closed.
1606 >&- The standard output is closed.
1608 <&p The input from the co-process is moved to standard input.
1610 >&p The output to the co-process is moved to standard output.
1612 <#((expr)) Evaluate arithmetic expression expr and position file de‐
1614 scriptor 0 to the resulting value bytes from the start of
1615 the file. The variables CUR and EOF evaluate to the cur‐
1616 rent offset and end-of-file offset respectively when
1617 evaluating expr.
1618 >#((offset)) The same as <# except applies to file descriptor 1.
1620 <#pattern Seeks forward to the beginning of the next line contain‐
1622 ing pattern.
1623 <##pattern The same as <# except that the portion of the file that
1625 is skipped is copied to standard output.
1626 If one of the above is preceded by a digit, with no intervening space,
1628 then the file descriptor number referred to is that specified by the
1629 digit (instead of the default 0 or 1). If one of the above, other than
1630 >&- and the ># and <# forms, is preceded by {varname} with no interven‐
1631 ing space, then a file descriptor number > 9 will be selected by the
1632 shell and stored in the variable varname, so it can be read from or
1633 written to with redirections like <& $varname or >& $varname. If >&-
1634 or the any of the ># and <# forms is preceded by {varname} the value of
1635 varname defines the file descriptor to close or position. For example:
1636 ... 2>&1
1638 means file descriptor 2 is to be opened for writing as a duplicate of
1640 file descriptor 1 and
1641 exec {n}<file
1643 means open file named file for reading and store the file descriptor
1645 number in variable n.
1646 A special shorthand redirection operator &>word is available; it is
1648 equivalent to >word 2>&1. It cannot be preceded by any digit or vari‐
1649 able name. This shorthand is disabled if the posix shell option is ac‐
1650 tive.
1651 The order in which redirections are specified is significant. The
1653 shell evaluates each redirection in terms of the (file descriptor,
1654 file) association at the time of evaluation. For example:
1655 ... 1>fname 2>&1
1657 first associates file descriptor 1 with file fname. It then associates
1659 file descriptor 2 with the file associated with file descriptor 1 (i.e.
1660 fname). If the order of redirections were reversed, file descriptor 2
1661 would be associated with the terminal (assuming file descriptor 1 had
1662 been) and then file descriptor 1 would be associated with file fname.
1663 If a command is followed by & and job control is not active, then the
1665 default standard input for the command is the empty file /dev/null.
1666 Otherwise, the environment for the execution of a command contains the
1667 file descriptors of the invoking shell as modified by input/output
1668 specifications.
1669 Environment.
1671 The environment (see environ(7)) is a list of name-value pairs that is
1672 passed to an executed program in the same way as a normal argument
1673 list. The names must be identifiers and the values are character
1674 strings. The shell interacts with the environment in several ways. On
1675 invocation, the shell scans the environment and creates a variable for
1676 each name found, giving it the corresponding value and attributes and
1677 marking it export. Executed commands inherit the environment. If the
1678 user modifies the values of these variables or creates new ones, using
1679 the export or typeset -x commands, they become part of the environment.
1680 The environment seen by any executed command is thus composed of any
1681 name-value pairs originally inherited by the shell, whose values may be
1682 modified by the current shell, plus any additions which must be noted
1683 in export or typeset -x commands.
1684 The environment for any simple-command or function may be augmented by
1686 prefixing it with one or more variable assignments. A variable assign‐
1687 ment argument is a word of the form identifier=value. Thus:
1688 TERM=450 cmd args and
1690 (export TERM; TERM=450; cmd args)
1691 are equivalent (as far as the above execution of cmd is concerned ex‐
1693 cept for special built-in commands listed below - those that are marked
1694 with †).
1695 If the obsolete -k option is set, all variable assignment arguments are
1697 placed in the environment, even if they occur after the command name.
1698 The following first prints a=b c and then c:
1699 echo a=b c
1701 set -k
1702 echo a=b c
1703 This feature is intended for use with scripts written for early ver‐
1705 sions of the shell and its use in new scripts is strongly discouraged.
1706 It is likely to disappear someday.
1707 Functions.
1709 For historical reasons, there are two ways to define functions, the
1710 name() syntax and the function name syntax, described in the Commands
1711 section above. Shell functions are read in and stored internally.
1712 Alias names are resolved when the function is read. Functions are exe‐
1713 cuted like commands with the arguments passed as positional parameters.
1714 (See Execution below.)
1715 Functions defined by the function name syntax and called by name exe‐
1717 cute in the same process as the caller and share all files and present
1718 working directory with the caller. Traps caught by the caller are re‐
1719 set to their default action inside the function. A trap condition that
1720 is not caught or ignored by the function causes the function to termi‐
1721 nate and the condition to be passed on to the caller. A trap on EXIT
1722 set inside a function is executed in the environment of the caller af‐
1723 ter the function completes. Ordinarily, variables are shared between
1724 the calling program and the function. However, the typeset special
1725 built-in command used within a function defines local variables whose
1726 scope includes the current function. They can be passed to functions
1727 that they call in the variable assignment list that precedes the call
1728 or as arguments passed as name references. Errors within functions re‐
1729 turn control to the caller.
1730 Functions defined with the name() syntax and functions defined with the
1732 function name syntax that are invoked with the . special built-in are
1733 executed in the caller's environment and share all variables and traps
1734 with the caller. Errors within these function executions cause the
1735 script that contains them to abort.
1736 The special built-in command return is used to return from function
1738 calls.
1739 Function names can be listed with the -f or +f option of the typeset
1741 special built-in command. The text of functions, when available, will
1742 also be listed with -f. Functions can be undefined with the -f option
1743 of the unset special built-in command.
1744 Ordinarily, functions are unset when the shell executes a shell script.
1746 Functions that need to be defined across separate invocations of the
1747 shell should be placed in a directory and the FPATH variable should
1748 contain the name of this directory. They may also be specified in the
1749 ENV file.
1750 Discipline Functions.
1752 Each variable can have zero or more discipline functions associated
1753 with it. The shell initially understands the discipline names get,
1754 set, append, and unset but can be added when defining new types. On
1755 most systems others can be added at run time via the C programming in‐
1756 terface extension provided by the builtin built-in utility. If the get
1757 discipline is defined for a variable, it is invoked whenever the given
1758 variable is referenced. If the variable .sh.value is assigned a value
1759 inside the discipline function, the referenced variable will evaluate
1760 to this value instead. If the set discipline is defined for a vari‐
1761 able, it is invoked whenever the given variable is assigned a value.
1762 If the append discipline is defined for a variable, it is invoked when‐
1763 ever a value is appended to the given variable. The variable .sh.value
1764 is given the value of the variable before invoking the discipline, and
1765 the variable will be assigned the value of .sh.value after the disci‐
1766 pline completes. If .sh.value is unset inside the discipline, then
1767 that value is unchanged. If the unset discipline is defined for a
1768 variable, it is invoked whenever the given variable is unset.
1769 The variable .sh.name contains the name of the variable for which the
1771 discipline function is called, .sh.subscript is the subscript of the
1772 variable, and .sh.value will contain the value being assigned inside
1773 the set discipline function. The variable _ is a reference to the
1774 variable including the subscript if any. For the set discipline,
1775 changing .sh.value will change the value that gets assigned. Finally,
1776 the expansion ${var.name}, when name is the name of a discipline, and
1777 there is no variable of this name, is equivalent to the command substi‐
1778 tution ${ var.name;}.
1779 Name Spaces.
1782 Commands and functions that are executed as part of the list of a name‐
1783 space command that modify variables or create new ones, create a new
1784 variable whose name is the name of the name space as given by identi‐
1785 fier preceded by .. When a variable whose name is name is referenced,
1786 it is first searched for using .identifier.name. Similarly, a function
1787 defined by a command in the namespace list is created using the name
1788 space name preceded by a ..
1789 When the list of a namespace command contains a namespace command, the
1791 names of variables and functions that are created consist of the vari‐
1792 able or function name preceded by the list of identifiers each preceded
1793 by ..
1794 Outside of a name space, a variable or function created inside a name
1796 space can be referenced by preceding it with the name space name.
1797 By default, variables starting with .sh are in the sh name space.
1799 Type Variables.
1802 Typed variables provide a way to create data structure and objects. A
1803 type can be defined either by a shared library, by the enum built-in
1804 command described below, or by using the new -T option of the typeset
1805 built-in command. With the -T option of typeset, the type name, speci‐
1806 fied as an option argument to -T, is set with a compound variable as‐
1807 signment that defines the type. Function definitions can appear inside
1808 the compound variable assignment and these become discipline functions
1809 for this type and can be invoked or redefined by each instance of the
1810 type. The function name create is treated specially. It is invoked
1811 for each instance of the type that is created but is not inherited and
1812 cannot be redefined for each instance.
1813 When a type is defined a special built-in command of that name is
1815 added. These built-ins are declaration commands and follow the same
1816 expansion rules as the built-in commands described below that are
1817 marked with a ‡ symbol. These commands can subsequently be used inside
1818 further type definitions. The man page for these commands can be gen‐
1819 erated by using the --man option or any of the other -- options de‐
1820 scribed with getopts. The -r, -a, -A, -h, and -S options of typeset
1821 are permitted with each of these new built-ins.
1822 An instance of a type is created by invoking the type name followed by
1824 one or more instance names. Each instance of the type is initialized
1825 with a copy of the subvariables except for subvariables that are de‐
1826 fined with the -S option. Variables defined with the -S are shared by
1827 all instances of the type. Each instance can change the value of any
1828 subvariable and can also define new discipline functions of the same
1829 names as those defined by the type definition as well as any standard
1830 discipline names. No additional subvariables can be defined for any
1831 instance.
1832 When defining a type, if the value of a subvariable is not set and the
1834 -r attribute is specified, it causes the subvariable to be a required
1835 subvariable. Whenever an instance of a type is created, all required
1836 subvariables must be specified. These subvariables become read-only in
1837 each instance.
1838 When unset is invoked on a subvariable within a type, and the -r attri‐
1840 bute has not been specified for this field, the value is reset to the
1841 default value associative with the type. Invoking unset on a type in‐
1842 stance not contained within another type deletes all subvariables and
1843 the variable itself.
1844 A type definition can be derived from another type definition by defin‐
1846 ing the first subvariable name as _ and defining its type as the base
1847 type. Any remaining definitions will be additions and modifications
1848 that apply to the new type. If the new type name is the same as that
1849 of the base type, the type will be replaced and the original type will
1850 no longer be accessible.
1851 The typeset command with the -T and no option argument or operands will
1853 write all the type definitions to standard output in a form that can be
1854 read in to create all they types.
1855 Jobs.
1857 If the monitor option of the set command is turned on, an interactive
1858 shell associates a job with each pipeline. It keeps a table of current
1859 jobs, printed by the jobs command, and assigns them small integer num‐
1860 bers. When a job is started asynchronously with &, the shell prints a
1861 line which looks like:
1862 [1] 1234
1864 indicating that the job which was started asynchronously was job number
1866 1 and had one (top-level) process, whose process ID was 1234.
1867 This paragraph and the next require features that are not in all ver‐
1869 sions of UNIX and may not apply. If you are running a job and wish to
1870 do something else you may hit the key ^Z (control-Z) which sends a STOP
1871 signal to the current job. The shell will then normally indicate that
1872 the job has been `Stopped', and print another prompt. You can then ma‐
1873 nipulate the state of this job, putting it in the background with the
1874 bg command, or run some other commands and then eventually bring the
1875 job back into the foreground with the foreground command fg. A ^Z
1876 takes effect immediately and is like an interrupt in that pending out‐
1877 put and unread input are discarded when it is typed.
1878 A job being run in the background will stop if it tries to read from
1880 the terminal. Background jobs are normally allowed to produce output,
1881 but this can be disabled by giving the command stty tostop. If you set
1882 this tty option, then background jobs will stop when they try to pro‐
1883 duce output like they do when they try to read input.
1884 A job pool is a collection of jobs started with list & associated with
1886 a name.
1887 There are several ways to refer to jobs in the shell. A job can be re‐
1889 ferred to by the process ID of any process of the job or by one of the
1890 following:
1891 %number
1892 The job with the given number.
1893 pool All the jobs in the job pool named by pool.
1894 pool.number
1895 The job number number in the job pool named by pool.
1896 %string
1897 Any job whose command line begins with string.
1898 %?string
1899 Any job whose command line contains string.
1900 %% Current job.
1901 %+ Equivalent to %%.
1902 %- Previous job.
1903 In addition, unless noted otherwise, wherever a job can be specified,
1905 the name of a background job pool can be used to represent all the jobs
1906 in that pool.
1907 The shell learns immediately whenever a process changes state. It nor‐
1909 mally informs you whenever a job becomes blocked so that no further
1910 progress is possible, but only just before it prints a prompt. This is
1911 done so that it does not otherwise disturb your work. The notify op‐
1912 tion of the set command causes the shell to print these job change mes‐
1913 sages as soon as they occur.
1914 When the monitor option is on, each background job that completes trig‐
1916 gers any trap set for CHLD.
1917 When you try to leave the shell while jobs are running or stopped, you
1919 will be warned that `You have stopped(running) jobs.' You may use the
1920 jobs command to see what they are. If you immediately try to exit
1921 again, the shell will not warn you a second time, and the stopped jobs
1922 will be terminated. When a login shell receives a HUP signal, it sends
1923 a HUP signal to each job that has not been disowned with the disown
1924 built-in command described below.
1925 Signals.
1927 The INT and QUIT signals for an invoked command are ignored if the com‐
1928 mand is followed by & and the monitor option is not active. Otherwise,
1929 signals have the values inherited by the shell from its parent (but see
1930 also the trap built-in command below).
1931 Execution.
1933 Each time a command is read, the above expansions and substitutions are
1934 carried out. If the command name matches one of the Special Built-in
1935 Commands listed below, it is executed within the current shell process.
1936 Next, the command name is checked to see if it matches a user defined
1937 function. If it does, the positional parameters are saved and then re‐
1938 set to the arguments of the function call. A function is also executed
1939 in the current shell process. When the function completes or issues a
1940 return, the positional parameter list is restored. For functions de‐
1941 fined with the function name syntax, any trap set on EXIT within the
1942 function is executed. The exit value of a function is the value of the
1943 last command executed. If a command name is not a special built-in
1944 command or a user defined function, but it is one of the built-in com‐
1945 mands listed below, it is executed in the current shell process.
1946 The shell variables PATH followed by the variable FPATH defines the
1948 list of directories to search for the command name. Alternative direc‐
1949 tory names are separated by a colon (:). The default path is the value
1950 that was output by getconf PATH at the time ksh was compiled. The cur‐
1951 rent directory can be specified by two or more adjacent colons, or by a
1952 colon at the beginning or end of the path list. If the command name
1953 contains a /, then the search path is not used. Otherwise, each direc‐
1954 tory in the list of directories defined by PATH and FPATH is checked in
1955 order. If the directory being searched is contained in FPATH and con‐
1956 tains a file whose name matches the command being searched, then this
1957 file is loaded into the current shell environment as if it were the ar‐
1958 gument to the . command except that only preset aliases are expanded,
1959 and a function of the given name is executed as described above.
1960 If this directory is not in FPATH the shell first determines whether
1962 there is a built-in version of a command corresponding to a given path‐
1963 name and if so it is invoked in the current process. If no built-in is
1964 found, the shell checks for a file named .paths in this directory. If
1965 found and there is a line of the form FPATH=path where path names an
1966 existing directory then that directory is searched immediately after
1967 the current directory as if it were found in the FPATH variable. If
1968 path does not begin with /, it is checked for relative to the directory
1969 being searched.
1970 The .paths file is then checked for a line of the form PLUGIN_LIB=lib‐
1972 name [ : libname ] ... . Each library named by libname will be
1973 searched for as if it were an option argument to builtin -f, and if it
1974 contains a built-in of the specified name this will be executed instead
1975 of a command by this name. Any built-in loaded from a library found
1976 this way will be associated with the directory containing the .paths
1977 file so it will only execute if not found in an earlier directory.
1978 Finally, the directory will be checked for a file of the given name.
1980 If the file has execute permission but is not an a.out file, it is as‐
1981 sumed to be a file containing shell commands. A separate shell is
1982 spawned to read it. All non-exported variables are removed in this
1983 case. If the shell command file doesn't have read permission, or if
1984 the setuid and/or setgid bits are set on the file, then the shell exe‐
1985 cutes an agent whose job it is to set up the permissions and execute
1986 the shell with the shell command file passed down as an open file. If
1987 the .paths contains a line of the form name=value in the first or sec‐
1988 ond line, then the environment variable name is modified by prepending
1989 the directory specified by value to the directory list. If value is
1990 not an absolute directory, then it specifies a directory relative to
1991 the directory that the executable was found. If the environment vari‐
1992 able name does not already exist it will be added to the environment
1993 list for the specified command. A parenthesized command is executed in
1994 a subshell without removing non-exported variables.
1995 Command Re-entry.
1997 The text of the last HISTSIZE (default 512) commands entered from a
1998 terminal device is saved in a history file. The file $HOME/.sh_history
1999 is used if the HISTFILE variable is not set or if the file it names is
2000 not writable. A shell can access the commands of all interactive
2001 shells which use the same named HISTFILE. The built-in command hist is
2002 used to list or edit a portion of this file. The portion of the file
2003 to be edited or listed can be selected by number or by giving the first
2004 character or characters of the command. A single command or range of
2005 commands can be specified. If you do not specify an editor program as
2006 an argument to hist then the value of the variable HISTEDIT is used.
2007 If HISTEDIT is unset, the obsolete variable FCEDIT is used. If FCEDIT
2008 is not defined, then /bin/ed is used. The edited command(s) is printed
2009 and re-executed upon leaving the editor unless you quit without writ‐
2010 ing. The -s option (and in obsolete versions, the editor name -) is
2011 used to skip the editing phase and to re-execute the command. In this
2012 case a substitution parameter of the form old=new can be used to modify
2013 the command before execution. For example, with the preset alias r,
2014 which is aliased to ′hist -s′, typing `r bad=good c' will re-execute
2015 the most recent command which starts with the letter c, replacing the
2016 first occurrence of the string bad with the string good.
2017 History Expansion.
2019 History expansions introduce words from the history list into the input
2020 stream, making it easy to repeat commands, repeat arguments of a previ‐
2021 ous command in the current command, or fix typos in the previous com‐
2022 mand. The history expansion facility is an alternative to history con‐
2023 trol via the fc or hist built-in command. To enable it, turn on the -H
2024 or histexpand option using the set command (see Built-in Commands be‐
2025 low).
2026 History expansions begin with the character !. They may begin anywhere
2028 in the input. The ! may be preceded by a \ or enclosed in single
2029 quotes to prevent its special meaning. A ! is also passed unchanged
2030 when it is followed by a space, tab, newline, = or (. History expan‐
2031 sions do not nest. They are parsed separately before the shell parser
2032 is invoked, so they can override shell grammar rules.
2033 By default, the expanded version of any line that contains a history
2035 expansion is printed, added to the history, and then immediately exe‐
2036 cuted. History expansions are never added to the history themselves,
2037 regardless of whether they succeed or fail due to an error. Normally,
2038 this means that a command line with an erroneous history expansion is
2039 lost and needs to be retyped from scratch, but if the histreedit shell
2040 option is turned on and a line editor is active (see In-line Editing
2041 Options below), the erroneous line is pre-filled into the next prompt's
2042 input buffer for correcting. The histverify option causes the same to
2043 be done for successful history expansions, allowing verification and
2044 editing before execution.
2045 A history expansion may have an event specification, which indicates
2047 the event from which words are to be taken, a word designator, which
2048 selects particular words from the chosen event, and/or a modifier,
2049 which manipulates the selected words.
2050 An event specification can be:
2052 n A number, referring to a particular event.
2054 -n An offset, referring to the event n before the current
2055 event.
2056 # The current event.
2057 ! The previous event (equivalent to -1).
2058 s The most recent event whose first word begins with the
2059 string s.
2060 ?s? The most recent event which contains the string s. The
2061 second ? can be omitted if it is immediately followed by a
2062 newline.
2063 For example, consider this bit of someone's history list as might be
2065 output by the hist -l command:
2066 9 nroff -man wumpus.man
2068 10 cp wumpus.man wumpus.man.old
2069 11 vi wumpus.man
2070 12 diff wumpus.man.old wumpus.man
2071 The commands are shown with their event numbers. The current event,
2073 which we haven't typed in yet, is event 13. !11 and !-2 refer to event
2074 11. !! refers to the previous event, 12. !! can be abbreviated ! if
2075 it is followed by : (see below). !n refers to event 9, which begins
2076 with n. !?old? also refers to event 12, which contains old. Without
2077 word designators or modifiers, history references simply expand to the
2078 entire event, so we might type !cp to redo the copy command or !!|more
2079 if the diff output scrolled off the top of the screen.
2080 To select words from an event, the event specification can be followed
2082 by a : and a designator for the desired words. The words of an input
2083 line are numbered from 0, the first word (usually the command name) be‐
2084 ing 0, the second word (first argument) being 1, etc. The basic word
2085 designators are:
2086 0 The first word (command name).
2088 n The nth argument.
2089 ^ The first argument, equivalent to 1.
2090 $ The last argument.
2091 % The word matched by the most recent ?s? search.
2092 x-y A range of words.
2093 -y Equivalent to 0-y.
2094 * Equivalent to ^-$, but returns nothing if the event con‐
2095 tains only 1 word.
2096 x* Equivalent to x-$.
2097 x- Equivalent to x*, but omitting the last word ($).
2098 Selected words are inserted into the command line separated by single
2100 blanks. For example, the diff command in the previous example might
2101 have been typed as diff !!:1.old !!:1 (using :1 to select the first ar‐
2102 gument from the previous event) or diff !-2:2 !-2:1 to select and swap
2103 the arguments from the cp command. If we didn't care about the order
2104 of the diff, we might have said diff !-2:1-2 or simply diff !-2:*. The
2105 cp command might have been written cp wumpus.man !#:1.old, using # to
2106 refer to the current event. !n:- hurkle.man would reuse the first two
2107 words from the nroff command to say nroff -man hurkle.man.
2108 The : separating the event specification from the word designator can
2110 be omitted if the argument selector begins with a ^, $, *, % or -. For
2111 example, our diff command might have been diff !!^.old !!^ or, equiva‐
2112 lently, diff !!$.old !!$. However, if !! is abbreviated !, an argument
2113 selector beginning with - will be interpreted as an event specifica‐
2114 tion.
2115 The word(s) in a history reference can be edited by following them with
2117 one or more modifiers, each preceded by a colon (:):
2118 h Remove a trailing pathname component, leaving the head.
2120 t Remove all leading pathname components, leaving the tail.
2121 r Remove a filename extension .xxx, leaving the root name.
2122 e Remove all but the extension.
2123 s/l/r/ Substitute l for r. l is simply a string like r, not a
2124 regular expression as in the eponymous ed(1) command. Any
2125 character may be used as the delimiter in place of /; a \
2126 can be used to quote the delimiter inside l and r. The
2127 character & in the r is replaced by l; \ also quotes &. If
2128 l is empty, the l from the previous substitution is used,
2129 or if there is none, the s from the most recent ?s? search.
2130 The trailing delimiter may be omitted if it is immediately
2131 followed by a newline.
2132 & Repeat the previous substitution.
2133 g Global substitution, for example :gs/foo/bar/ or :g&. Ap‐
2134 plies the s or & modifier to the entire command line.
2135 a Same as g.
2136 p Print the new command line but do not execute it.
2137 q Quote the expanded words, preventing further expansions.
2138 x Like q, but break into words at blanks, tabs and newlines.
2139 Modifiers are applied to only the first modifiable word (unless g or a
2141 is used). It is an error for no word to be modifiable.
2142 For example, the diff command might have been written as diff wum‐
2144 pus.man.old !#^:r, using :r to remove .old from the first argument on
2145 the same line (!#^). We might follow mail -s "I forgot my password"
2146 rot with !:s/rot/root to correct the spelling of root.
2147 History expansions also occur when an input line begins with ^. When
2149 it is the first character on an input line, it is an abbreviation of
2150 !:s^. Thus we might have said ^rot^root to make the spelling correc‐
2151 tion in the previous example. This is the only history expansion that
2152 does not explicitly begin with !.
2153 If a word on a command line begins with the history comment character
2155 #, history expansion is ignored for the rest of that line. This usu‐
2156 ally causes the shell parser (which uses the same character to signal a
2157 comment) to treat the rest of the line as a comment as well, but as
2158 history expansion is parsed separately from the shell grammar and with
2159 different rules, this cannot be guaranteed in all cases. If the his‐
2160 tory comment character is changed, the shell grammar comment character
2161 does not change along with it.
2162 The three characters used to signal history expansion can be changed
2164 using the histchars shell variable; see Shell Variables above.
2165 In-line Editing Options.
2167 Normally, each command line entered from a terminal device is simply
2168 typed followed by a new-line (`RETURN' or `LINE FEED'). If either the
2169 emacs, gmacs, or vi option is active, the user can edit the command
2170 line. To be in either of these edit modes, set the corresponding op‐
2171 tion. An editing option is automatically selected each time the VISUAL
2172 or EDITOR variable is assigned a value matching any of these editor
2173 names; for details, see Shell Variables above under VISUAL.
2174 The editing features require that the user's terminal accept `RETURN'
2176 as carriage return without line feed and that a space (` ') must over‐
2177 write the current character on the screen.
2178 Unless the multiline option is on, the editing modes implement a con‐
2180 cept where the user is looking through a window at the current line.
2181 The window width is the value of COLUMNS if it is defined, otherwise
2182 80. If the window width is too small to display the prompt and leave
2183 at least 8 columns to enter input, the prompt is truncated from the
2184 left. If the line is longer than the window width minus two, a mark is
2185 displayed at the end of the window to notify the user. As the cursor
2186 moves and reaches the window boundaries, the window will be centered
2187 about the cursor. The mark is a > (<, *) if the line extends on the
2188 right (left, both) side(s) of the window.
2189 The search commands in each edit mode provide access to the history
2191 file. Only strings are matched, not patterns, although a leading ^ in
2192 the string restricts the match to begin at the first character in the
2193 line.
2194 Each of the edit modes has an operation to list the files or commands
2196 that match a partially entered word. When applied to the first word on
2197 the line, or the first word after a ;, |, &, or (, and the word does
2198 not begin with ∼ or contain a /, the list of aliases, functions, and
2199 executable commands defined by the PATH variable that could match the
2200 partial word is displayed. Otherwise, the list of files that match the
2201 given word is displayed. If the partially entered word does not con‐
2202 tain any file expansion characters, a * is appended before generating
2203 these lists. After displaying the generated list, the input line is
2204 redrawn. These operations are called command name listing and file
2205 name listing, respectively. There are additional operations, referred
2206 to as command name completion and file name completion, which compute
2207 the list of matching commands or files, but instead of printing the
2208 list, replace the current word with a complete or partial match. For
2209 file name completion, if the match is unique, a / is appended if the
2210 file is a directory and a space is appended if the file is not a direc‐
2211 tory. Otherwise, the longest common prefix for all the matching files
2212 replaces the word. For command name completion, only the portion of
2213 the file names after the last / are used to find the longest command
2214 prefix. If only a single name matches this prefix, then the word is
2215 replaced with the command name followed by a space. When using a tab
2216 for completion that does not yield a unique match, a subsequent tab
2217 will provide a numbered list of matching alternatives. A specific se‐
2218 lection can be made by entering the selection number followed by a tab.
2219 Neither completion nor listing operations are attempted before the
2220 first character in a line.
2221 Key Bindings.
2223 The KEYBD trap can be used to intercept keys as they are typed and
2224 change the characters that are actually seen by the shell. This trap
2225 is executed after each character (or sequence of characters when the
2226 first character is ESC) is entered while reading from a terminal. The
2227 variable .sh.edchar contains the character or character sequence which
2228 generated the trap. Changing the value of .sh.edchar in the trap ac‐
2229 tion causes the shell to behave as if the new value were entered from
2230 the keyboard rather than the original value.
2231 The variable .sh.edcol is set to the input column number of the cursor
2233 at the time of the input. The variable .sh.edmode is set to ESC when
2234 in vi insert mode (see below) and set to the empty string otherwise.
2235 Prepending ${.sh.editmode} to a value assigned to .sh.edchar will cause
2236 the shell to change to control mode if it is not already in this mode.
2237 This trap is not invoked for characters entered as arguments to editing
2239 directives, or while reading input for a character search.
2240 Emacs Editing Mode.
2242 This mode is entered by enabling either the emacs or gmacs option. The
2243 only difference between these two modes is the way they handle ^T. To
2244 edit, the user moves the cursor to the point needing correction and
2245 then inserts or deletes characters or words as needed. All the editing
2246 commands are control characters or escape sequences. The notation for
2247 control characters is caret (^) followed by the character. For exam‐
2248 ple, ^F is the notation for control F. This is entered by depressing
2249 `f' while holding down the `CTRL' (control) key. The `SHIFT' key is
2250 not depressed. (The notation ^? indicates the DEL (delete) key.)
2251 The notation for escape sequences is M- followed by a character. For
2253 example, M-f (pronounced Meta f) is entered by depressing ESC (ASCII
2254 033) followed by `f'. (M-F would be the notation for ESC followed by
2255 `SHIFT' (capital) `F'.)
2256 All edit commands operate from any place on the line (not just at the
2258 beginning). Neither the `RETURN' nor the `LINE FEED' key is entered
2259 after edit commands except when noted.
2260 The M-[ multi-character commands below are DEC VT220 escape sequences
2262 generated by special keys on standard PC keyboards, such as the arrow
2263 keys. You could type them directly but they are meant to recognize the
2264 keys in question, which are indicated in parentheses.
2265 ^F Move cursor forward (right) one character.
2267 M-[C (Right arrow) Same as ^F.
2268 M-f Move cursor forward one word. (The emacs editor's idea of a
2269 word is a string of characters consisting of only letters,
2270 digits and underscores.)
2271 M-[1;3C (Alt-Right arrow) Same as M-f.
2272 M-[1;5C (Ctrl-Right arrow) Same as M-f.
2273 M-[1;9C (iTerm2 Alt-Right arrow) Same as M-f.
2274 ^B Move cursor backward (left) one character.
2275 M-[D (Left arrow) Same as ^B.
2276 M-b Move cursor backward one word.
2277 M-[1;3D (Alt-Left arrow) Same as M-b.
2278 M-[1;5D (Ctrl-Left arrow) Same as M-b.
2279 M-[1;9D (iTerm2 Alt-Left arrow) Same as M-b.
2280 ^A Move cursor to start of line.
2281 M-[H (Home) Same as ^A.
2282 M-[1~ Same as ^A.
2283 M-[7~ Same as ^A.
2284 ^E Move cursor to end of line.
2285 M-[F (End) Same as ^E.
2286 M-[4~ Same as ^E.
2287 M-[8~ Same as ^E.
2288 M-[Y Same as ^E.
2289 M-OA (Up Arrow) Same as M-[A.
2290 M-OB (Down Arrow) Same as M-[B.
2291 M-OC (Right Arrow) Same as M-[C.
2292 M-OD (Left Arrow) Same as M-[D.
2293 M-O5C (Ctrl-Right Arrow) Same as M-f.
2294 M-O5D (Ctrl-Left Arrow) Same as M-b.
2295 ^]char Move cursor forward to character char on current line.
2296 M-^]char Move cursor backward to character char on current line.
2297 ^X^X Interchange the cursor and mark.
2298 erase (User defined erase character as defined by the stty(1) com‐
2299 mand, usually ^H .) Delete previous character.
2300 lnext (User defined literal next character as defined by the
2301 stty(1) command, or ^V if not defined.) Removes the next
2302 character's editing features (if any).
2303 ^D Delete current character.
2304 M-[3~ (Forward delete) Same as ^D.
2305 M-d Delete current word.
2306 M-[3;5~ (Ctrl-Delete) Same as M-d.
2307 M-^H (Meta-backspace) Delete previous word.
2308 M-h Delete previous word.
2309 M-^? (Meta-DEL) Delete previous word (if your interrupt character
2310 is ^? (DEL, the default) then this command will not work).
2311 ^T Transpose current character with previous character and ad‐
2312 vance the cursor in emacs mode. Transpose two previous char‐
2313 acters in gmacs mode.
2314 ^C Capitalize current character.
2315 M-c Capitalize current word.
2316 M-l Change the current word to lower case.
2317 ^K Delete from the cursor to the end of the line. If preceded
2318 by a numerical parameter whose value is less than the current
2319 cursor position, then delete from given position up to the
2320 cursor. If preceded by a numerical parameter whose value is
2321 greater than the current cursor position, then delete from
2322 cursor up to given cursor position.
2323 ^W Kill from the cursor to the mark.
2324 M-p Push the region from the cursor to the mark on the stack.
2325 kill (User defined kill character as defined by the stty command,
2326 usually ^U .) Kill the entire current line. If two kill
2327 characters are entered in succession, all kill characters
2328 from then on cause a line feed (useful when using paper ter‐
2329 minals). A subsequent pair of kill characters undoes this
2330 change.
2331 ^Y Restore last item removed from line. (Yank item back to the
2332 line.)
2333 ^L Line feed and print current line.
2334 M-^L Clear the screen.
2335 ^@ (Null character) Set mark.
2336 M-space (Meta space) Set mark.
2337 ^J (New line) Execute the current line.
2338 ^M (Return) Execute the current line.
2339 eof End-of-file character, normally ^D, is processed as an End-
2340 of-file only if the current line is empty.
2341 ^P Fetch previous command. Each time ^P is entered the previous
2342 command back in time is accessed. Moves back one line when
2343 not on the first line of a multi-line command.
2344 M-[A (Up arrow) If the cursor is at the end of the line, it is
2345 equivalent to ^R with string set to the contents of the cur‐
2346 rent line. Otherwise, it is equivalent to ^P.
2347 M-< Fetch the least recent (oldest) history line.
2348 M-> Fetch the most recent (youngest) history line.
2349 ^N Fetch next command line. Each time ^N is entered the next
2350 command line forward in time is accessed.
2351 M-[B (Down arrow) Equivalent to ^N.
2352 ^Rstring Reverse search history for a previous command line containing
2353 string. If a parameter of zero is given, the search is for‐
2354 ward. String is terminated by a `RETURN' or `NEW LINE'. If
2355 string is preceded by a ^, the matched line must begin with
2356 string. If string is omitted, then the next command line
2357 containing the most recent string is accessed. In this case
2358 a parameter of zero reverses the direction of the search.
2359 ^G Exit reverse search mode.
2360 ^O Operate - Execute the current line and fetch the next line
2361 relative to current line from the history file.
2362 M-digits (Escape) Define numeric parameter, the digits are taken as a
2363 parameter to the next command. The commands that accept a
2364 parameter are ^F, ^B, erase, ^C, ^D, ^K, ^R, ^P, ^N, ^], M-.,
2365 M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l, M-^H, and the
2366 arrow keys and forward-delete key.
2367 M-letter Soft-key - Your alias list is searched for an alias by the
2368 name _letter and if an alias of this name is defined, its
2369 value will be inserted on the input queue. The letter must
2370 not be one of the above meta-functions.
2371 M-[letter Soft-key - Your alias list is searched for an alias by the
2372 name __letter and if an alias of this name is defined, its
2373 value will be inserted on the input queue. This can be used
2374 to program function keys on many terminals.
2375 M-. The last word of the previous command is inserted on the
2376 line. If preceded by a numeric parameter, the value of this
2377 parameter determines which word to insert rather than the
2378 last word.
2379 M-_ Same as M-..
2380 M-* Attempt pathname expansion on the current word. An asterisk
2381 is appended if the word doesn't match any file or contain any
2382 special pattern characters.
2383 M-ESC Command or file name completion as described above.
2384 ^I tab Attempts command or file name completion as described above.
2385 If a partial completion occurs, repeating this will behave as
2386 if M-= were entered. If no match is found or entered after
2387 space, a tab is inserted.
2388 M-= If not preceded by a numeric parameter, it generates the list
2389 of matching commands or file names as described above. Oth‐
2390 erwise, the word under the cursor is replaced by the item
2391 corresponding to the value of the numeric parameter from the
2392 most recently generated command or file list. If the cursor
2393 is not on a word, it is inserted instead.
2394 ^U Multiply parameter of next command by 4.
2395 \ If the backslashctrl shell option is on (which is the default
2396 setting), this escapes the next character. Editing charac‐
2397 ters, the user's erase, kill and interrupt (normally ^C)
2398 characters may be entered in a command line or in a search
2399 string if preceded by a \. The \ removes the next charac‐
2400 ter's editing features (if any). See also lnext which is not
2401 subject to any shell option.
2402 M-^V Display version of the shell.
2403 M-[2~ (Insert) Escape the next character.
2404 M-# If the line does not begin with a #, a # is inserted at the
2405 beginning of the line and after each new-line, and the line
2406 is entered. This causes a comment to be inserted in the his‐
2407 tory file. If the line begins with a #, the # is deleted and
2408 one # after each new-line is also deleted.
2409 Vi Editing Mode.
2411 There are two typing modes. Initially, when you enter a command you
2412 are in the input mode. To edit, the user enters control mode by typing
2413 ESC (033) and moves the cursor to the point needing correction and then
2414 inserts or deletes characters or words as needed. Most control com‐
2415 mands accept an optional repeat count prior to the command.
2416 The notation for control characters used below is ^ followed by a char‐
2418 acter. For instance, ^H is entered by holding down the Control key and
2419 pressing H. ^[ (Control+[) is equivalent to the ESC key. The notation
2420 for escape sequences is ^[ followed by one or more characters.
2421 The ^[[ (ESC [) multi-character commands below are DEC VT220 escape se‐
2423 quences generated by special keys on standard PC keyboards, such as the
2424 arrow keys, which are indicated in parentheses. When in input mode,
2425 these keys will switch you to control mode before performing the asso‐
2426 ciated action. These sequences can use preceding repeat count parame‐
2427 ters, but only when the ^[ and the subsequent [ are entered into the
2428 input buffer at the same time, such as when pressing one of those keys.
2429 Input Edit Commands
2431 By default the editor is in input mode.
2432 erase (User defined erase character as defined by the stty
2434 command, usually ^H or #.) Delete previous character.
2435 ^W Delete the previous blank separated word. On some
2436 systems the viraw option may be required for this to
2437 work.
2438 eof As the first character of the line causes the shell to
2439 terminate unless the ignoreeof option is set. Other‐
2440 wise this character is ignored.
2441 lnext (User defined literal next character as defined by the
2442 stty(1) or ^V if not defined.) Removes the next char‐
2443 acter's editing features (if any). On some systems
2444 the viraw option may be required for this to work.
2445 \ If the backslashctrl shell option is on (which is the
2446 default setting), this escapes the next erase or kill
2447 character.
2448 ^I tab Attempts command or file name completion as described
2449 above and returns to input mode. If a partial comple‐
2450 tion occurs, repeating this will behave as if = were
2451 entered from control mode. If no match is found or
2452 entered after space, a tab is inserted.
2453 Motion Edit Commands
2455 These commands will move the cursor.
2456 [count]l Cursor forward (right) one character.
2458 [count]^[[C
2459 (Right arrow) Same as l.
2460 [count]w Cursor forward one alphanumeric word.
2461 [count]W Cursor to the beginning of the next word that follows
2462 a blank.
2463 [count]e Cursor to end of word.
2464 [count]E Cursor to end of the current blank delimited word.
2465 [count]h Cursor backward (left) one character.
2466 [count]^[[D
2467 (Left arrow) Same as h.
2468 [count]b Cursor backward one word.
2469 [count]B Cursor to preceding blank separated word.
2470 [count]| Cursor to column count.
2471 [count]fc Find the next character c in the current line.
2472 [count]Fc Find the previous character c in the current line.
2473 [count]tc Equivalent to f followed by h.
2474 [count]Tc Equivalent to F followed by l.
2475 [count]; Repeats count times, the last single character find
2476 command, f, F, t, or T.
2477 [count], Reverses the last single character find command count
2478 times.
2479 0 Cursor to start of line.
2480 ^[[H (Home) Same as 0.
2481 ^[[1~ Same as 0.
2482 ^[[7~ Same as 0.
2483 ^[[1;3D (Alt-Left arrow) Same as b.
2484 ^[[1;5D (Ctrl-Left arrow) Same as b.
2485 ^[[1;9D (iTerm2 Alt-Left arrow) Same as b.
2486 ^[[1;3C (Alt-Right arrow) Same as w.
2487 ^[[1;5C (Ctrl-Right arrow) Same as w.
2488 ^[[1;9C (iTerm2 Alt-Right arrow) Same as w.
2489 ^[[2~ (Insert) Same as i.
2490 ^[[3;5~ (Ctrl-Delete) Same as dw.
2491 ^[OA (Up Arrow) Same as ^[[A.
2492 ^[OB (Down Arrow) Same as ^[[B.
2493 ^[OC (Right Arrow) Same as ^[[C.
2494 ^[OD (Left Arrow) Same as ^[[D.
2495 ^[O5C (Ctrl-Right Arrow) Same as w.
2496 ^[O5D (Ctrl-Left Arrow) Same as b.
2497 ^ Cursor to first non-blank character in line.
2498 $ Cursor to end of line.
2499 ^[[F (End) Same as $.
2500 ^[[4~ Same as $.
2501 ^[[8~ Same as $.
2502 ^[[Y Same as $.
2503 ^G Exit reverse search mode.
2504 % Moves to balancing (, ), {, }, [, or ]. If cursor is
2505 not on one of the above characters, the remainder of
2506 the line is searched for the first occurrence of one
2507 of the above characters first.
2508 Search Edit Commands
2510 These commands access your command history.
2511 [count]k Fetch previous command. Each time k is entered the
2513 previous command back in time is accessed.
2514 [count]- Equivalent to k.
2515 [count]^[[A
2516 (Up arrow) If cursor is at the end of the line it is
2517 equivalent to / with string set to the contents of the
2518 current line. Otherwise, it is equivalent to k.
2519 [count]j Fetch next command. Each time j is entered the next
2520 command forward in time is accessed.
2521 [count]+ Equivalent to j.
2522 [count]^[[B
2523 (Down arrow) Equivalent to j.
2524 [count]G The command number count is fetched. The default is
2525 the least recent history command.
2526 /string Search backward through history for a previous command
2527 containing string. String is terminated by a `RETURN'
2528 or `NEW LINE'. If string is preceded by a ^, the
2529 matched line must begin with string. If string is
2530 empty, the previous string will be used.
2531 ?string Same as / except that search will be in the forward
2532 direction.
2533 n Search for next match of the last pattern to / or ?
2534 commands.
2535 N Search for next match of the last pattern to / or ?,
2536 but in reverse direction.
2537 Text Modification Edit Commands
2539 These commands will modify the line.
2540 a Enter input mode and enter text after the current
2542 character.
2543 A Append text to the end of the line. Equivalent to $a.
2544 [count]cmotion
2545 c[count]motion
2546 Delete current character through the character that
2547 motion would move the cursor to and enter input mode.
2548 If motion is c, the entire line will be deleted and
2549 input mode entered.
2550 C Delete the current character through the end of line
2551 and enter input mode. Equivalent to c$.
2552 S Equivalent to cc.
2553 [count]s Replace characters under the cursor in input mode.
2554 D Delete the current character through the end of line.
2555 Equivalent to d$.
2556 [count]dmotion
2557 d[count]motion
2558 Delete current character through the character that
2559 motion would move to. If motion is d , the entire
2560 line will be deleted.
2561 i Enter input mode and insert text before the current
2562 character.
2563 I Insert text before the first non-blank character.
2564 Equivalent to ^i.
2565 [count]P Place the previous text modification before the cur‐
2566 sor.
2567 [count]p Place the previous text modification after the cursor.
2568 R Enter input mode and replace characters on the screen
2569 with characters you type overlay fashion.
2570 [count]rc Replace the count character(s) starting at the current
2571 cursor position with c, and advance the cursor.
2572 [count]x Delete current character.
2573 [count]^[[3~
2574 (Forward delete) Same as x.
2575 [count]X Delete preceding character.
2576 [count]. Repeat the previous text modification command.
2577 [count]∼ Invert the case of the count character(s) starting at
2578 the current cursor position and advance the cursor.
2579 [count]_ Causes the count word of the previous command to be
2580 appended and input mode entered. The last word is
2581 used if count is omitted.
2582 * Causes an * to be appended to the current word and
2583 pathname expansion attempted. If no match is found,
2584 it rings the bell. Otherwise, the word is replaced by
2585 the matching pattern and input mode is entered.
2586 \ Command or file name completion as described above.
2587 Other Edit Commands
2589 Miscellaneous commands.
2590 [count]ymotion
2592 y[count]motion
2593 Yank current character through character that motion
2594 would move the cursor to and puts them into the delete
2595 buffer. The text and cursor are unchanged.
2596 yy Yanks the entire line.
2597 Y Yanks from current position to end of line. Equiva‐
2598 lent to y$.
2599 u Undo the last text modifying command.
2600 U Undo all the text modifying commands performed on the
2601 line.
2602 [count]v Returns the command hist -e ${VISUAL:-${EDITOR:-vi}}
2603 count in the input buffer. If count is omitted, then
2604 the current line is used.
2605 ^L Line feed and print current line. Has effect only in
2606 control mode.
2607 ^J (New line) Execute the current line, regardless of
2608 mode.
2609 ^M (Return) Execute the current line, regardless of mode.
2610 # If the first character of the command is a #, then
2611 this command deletes this # and each # that follows a
2612 newline. Otherwise, sends the line after inserting a
2613 # in front of each line in the command. Useful for
2614 causing the current line to be inserted in the history
2615 as a comment and uncommenting previously commented
2616 commands in the history file.
2617 [count]= If count is not specified, it generates the list of
2618 matching commands or file names as described above.
2619 Otherwise, the word under the cursor is replaced by
2620 the count item from the most recently generated com‐
2621 mand or file list. If the cursor is not on a word, it
2622 is inserted instead.
2623 @letter Your alias list is searched for an alias by the name
2624 _letter and if an alias of this name is defined, its
2625 value will be inserted on the input queue for process‐
2626 ing.
2627 ^V Display version of the shell.
2628 Built-in Commands.
2630 The simple-commands listed below are built in to the shell and are exe‐
2631 cuted in the same process as the shell. The effects of any added In‐
2632 put/Output redirections are local to the command, except for the exec
2633 and redirect commands. Unless otherwise indicated, the output is writ‐
2634 ten on standard output (file descriptor 1) and the exit status, when
2635 there is no syntax error, is zero. Except for :, true, false, and
2636 echo, all built-in commands accept -- to indicate end of options, and
2637 are self-documenting.
2638 The self-documenting commands interpret the option --man as a request
2640 to display that command's own manual page, --help as a request to dis‐
2641 play the OPTIONS section from their manual page, and -? as a request
2642 to print a brief usage message. All these are processed as error mes‐
2643 sages, so they are written on standard error (file descriptor 2) and to
2644 pipe them into a pager such as more(1) you need to add a 2>&1 redirect‐
2645 ion before the |. The display of boldface text depends on whether stan‐
2646 dard error is on a terminal, so is disabled when using a pager. Export‐
2647 ing the ERROR_OPTIONS environment variable with a value containing em‐
2648 phasis will force this on; a value containing noemphasis forces it off.
2649 The test/[ command needs an additional -- argument to recognize self-
2650 documentation options, e.g. test --man --. The exec and redirect com‐
2651 mands, as they make redirections permanent, should use self-documenta‐
2652 tion options in a subshell when redirecting, for example: (redirect
2653 --man) 2>&1. There are advanced output options as well; see getopts
2654 --man for more information.
2655 Commands that are preceded by a † symbol below are special built-
2657 in commands and are treated specially in the following ways:
2658 1. Variable assignment lists preceding the command remain in
2659 effect when the command completes.
2660 2. I/O redirections are processed after variable assign‐
2661 ments.
2662 3. Errors cause a script that contains them to abort.
2663 4. They are not valid function names.
2664 Commands that are preceded by a ‡ symbol below are declaration com‐
2666 mands. Any following words that are in the format of a variable as‐
2667 signment are expanded with the same rules as a variable assignment.
2668 This means that tilde expansion is performed after the = sign, array
2669 assignments of the form varname=(assign_list) are supported, and field
2670 splitting and pathname expansion are not performed.
2671 † : [ arg ... ]
2673 The command only expands parameters.
2674 † . name [ arg ... ]
2676 If name is a function defined with the function name reserved
2677 word syntax, the function is executed in the current environment
2678 (as if it had been defined with the name() syntax). Otherwise
2679 if name refers to a file, the file is read in its entirety and
2680 the commands are executed in the current shell environment. The
2681 search path specified by PATH is used to find the directory con‐
2682 taining the file. If any arguments arg are given, they become
2683 the positional parameters while processing the . command and
2684 the original positional parameters are restored upon completion.
2685 Otherwise the positional parameters are unchanged. The exit
2686 status is the exit status of the last command executed.
2687 [ expression ]
2689 The [ command is the same as test, with the exception that an
2690 additional closing ] argument is required. See test below.
2691 alias [ -ptx ] [ name[ =value ] ] ...
2693 alias with no arguments prints the list of aliases in the form
2694 name=value on standard output. The -p option causes the word
2695 alias to be inserted before each one. When one or more argu‐
2696 ments are given, an alias is defined for each name whose value
2697 is given. A trailing space in value causes the next word to be
2698 checked for alias substitution. With the -t option, each name
2699 is looked up as a command in $PATH and its path is added to the
2700 hash table as a 'tracked alias'. If no name is given, this
2701 prints the hash table. See hash. Without the -t option, for
2702 each name in the argument list for which no value is given, the
2703 name and value of the alias is printed. The obsolete -x option
2704 has no effect in most contexts, although if it's used with -t it
2705 will suppress all output. The exit status is non-zero if a name
2706 is given, but no value, and no alias has been defined for the
2707 name.
2708 autoload name ...
2710 Marks each name undefined so that the FPATH variable will be
2711 searched to find the function definition when the function is
2712 referenced. The same as typeset -fu.
2713 bg [ job... ]
2715 This command is only on systems that support job control. Puts
2716 each specified job into the background. The current job is put
2717 in the background if job is not specified. See Jobs for a de‐
2718 scription of the format of job.
2719 † break [ n ]
2721 Exit from the enclosing for, while, until, or select loop, if
2722 any. If n is specified, then break n levels.
2723 builtin [ -ds ] [ -f file ] [ name ... ]
2725 If name is not specified, and no -f option is specified, the
2726 built-ins are printed on standard output. The -s option prints
2727 only the special built-ins. Otherwise, each name represents the
2728 pathname whose basename is the name of the built-in. The entry
2729 point function name is determined by prepending b_ to the built-
2730 in name. A built-in specified by a pathname will only be exe‐
2731 cuted when that pathname would be found during the path search.
2732 Built-ins found in libraries loaded via the .paths file will as‐
2733 sociate with the pathname of the directory containing the .paths
2734 file.
2735 The ISO C/C++ prototype is b_mycommand(int argc, char *argv[],
2737 void *context) for the builtin command mycommand where argv is
2738 array an of argc elements and context is an optional pointer to
2739 a Shell_t structure as described in <ast/shell.h>.
2740 Special built-ins cannot be bound to a pathname or deleted. The
2742 -d option deletes each of the given built-ins. On systems that
2743 support dynamic loading, the -f option names a shared library
2744 containing the code for built-ins. The shared library prefix
2745 and/or suffix, which depend on the system, can be omitted. Once
2746 a library is loaded, its symbols become available for subsequent
2747 invocations of builtin. Multiple libraries can be specified
2748 with separate invocations of the builtin command. Libraries are
2749 searched in the reverse order in which they are specified. When
2750 a library is loaded, it looks for a function in the library
2751 whose name is lib_init() and invokes this function with an argu‐
2752 ment of 0.
2753 cd [ -L ] [ -eP ] [ arg ]
2755 cd [ -L ] [ -eP ] old new
2756 This command can be in either of two forms. In the first form
2757 it changes the current directory to arg. If arg is - the direc‐
2758 tory is changed to the previous directory. The shell variable
2759 HOME is the default arg. The variable PWD is set to the current
2760 directory. The shell variable CDPATH defines the search path
2761 for the directory containing arg. Alternative directory names
2762 are separated by a colon (:). The default path is the empty
2763 string (specifying the current directory). Note that the cur‐
2764 rent directory may be specified by a dot (.) or by an empty
2765 path name, either of which can appear immediately after the
2766 equal sign or between the colon delimiters anywhere else in the
2767 path list. If arg begins with a / then the search path is not
2768 used. Otherwise, each directory in the path is searched for
2769 arg.
2770 The second form of cd substitutes the string new for the string
2771 old in the current directory name, PWD, and tries to change to
2772 this new directory.
2773 By default, symbolic link names are treated literally when find‐
2774 ing the directory name. This is equivalent to the -L option.
2775 The -P option causes symbolic links to be resolved when deter‐
2776 mining the directory. The last instance of -L or -P on the com‐
2777 mand line determines which method is used.
2778 If -e and -P are both in effect and the correct PWD could not be
2779 determined after successfully changing the directory, cd will
2780 return with exit status one and produce no output. If any other
2781 error occurs while both flags are active, the exit status is
2782 greater than one.
2783 The cd command may not be executed by rksh.
2784 command [ -pvxV ] name [ arg ... ]
2786 With the -v option, command is equivalent to the built-in whence
2787 command described below. The -V option causes command to act
2788 like whence -v.
2789 Without the -v or -V options, command executes name with the ar‐
2791 guments given by arg. Functions and aliases will not be
2792 searched for when finding name. If name refers to a special
2793 built-in, as marked with † in this manual, command disables the
2794 special properties described above for that mark, executing the
2795 command as a regular built-in. (For example, using command set
2796 -o option-name prevents a script from terminating when an in‐
2797 valid option name is given.)
2798 The -p option causes the operating system's standard utilities
2800 path (as output by getconf PATH) to be searched rather than the
2801 one defined by the value of PATH.
2802 The -x option runs name as an external command, bypassing built-
2804 ins. If the arguments contain at least one word that expands to
2805 multiple arguments, such as "$@" or *.txt, then the -x option
2806 also allows executing external commands with argument lists that
2807 are longer than the operating system allows. This functionality
2808 is similar to xargs(1) but is easier to use. The shell does this
2809 by invoking the external command multiple times if needed, di‐
2810 viding the expanded argument list over the invocations. Any ar‐
2811 guments that come before the first word that expands to multiple
2812 arguments, as well as any that follow the last such word, are
2813 considered static arguments and are repeated for each invoca‐
2814 tion. This allows each invocation to use the same command op‐
2815 tions, as well as the same trailing destination arguments for
2816 commands like cp(1) or mv(1). When all invocations are com‐
2817 pleted, command -x exits with the status of the invocation that
2818 had the highest exit status. (Note that command -x may still
2819 fail with an "argument list too long" error if a single argument
2820 exceeds the maximum length of the argument list, or if a long
2821 arguments list contains no word that expands to multiple argu‐
2822 ments.)
2823 ‡ compound vname[=value] ...
2825 Causes each vname to be a compound variable. The same as type‐
2826 set -C.
2827 † continue [ n ]
2829 Resume the next iteration of the enclosing for, while, until, or
2830 select loop. If n is specified, then resume at the n-th enclos‐
2831 ing loop.
2832 disown [ job... ]
2834 Causes the shell not to send a HUP signal to each given job, or
2835 all active jobs if job is omitted, when a login shell termi‐
2836 nates.
2837 echo [ arg ... ]
2839 When the first arg does not begin with a -, and none of the ar‐
2840 guments contain a \, then echo prints each of its arguments sep‐
2841 arated by a space and terminated by a new-line. Otherwise, the
2842 behavior of echo is system dependent and print or printf de‐
2843 scribed below should be used. See echo(1) for usage and de‐
2844 scription.
2845 ‡ enum [ -i ] type[=(value ...) ] ...
2847 Creates, for each type specified, an enumeration type declara‐
2848 tion command named type. Variables of the created type can only
2849 store any one of the values given. For example, enum
2850 bool=(false true) creates a Boolean variable type of which vari‐
2851 ables may be declared like bool x=true y=false. If =(value ...)
2852 is omitted, then type must be an indexed array variable with at
2853 least two elements and the values are taken from this array
2854 variable. If -i is specified the values are case-insensitive.
2855 Declaration commands are created as special builtins that cannot
2856 be removed or overridden by shell functions. Each created dec‐
2857 laration command has a --man option that shows documentation on
2858 its type's behavior and possible values.
2859 Within arithmetic expressions (see Arithmetic Evaluation above),
2861 enumeration type values translate to index numbers between 0 and
2862 the number of defined values minus 1. It is an error for an
2863 arithmetic expression to assign a value outside of that range.
2864 Decimal fractions are ignored. Taking the bool type from the
2865 example above, if a variable of this type is used in an arith‐
2866 metic expression, false translates to 0 and true to 1. Enumera‐
2867 tion values may also be used directly in an arithmetic expres‐
2868 sion that refers to a variable of an enumeration type. To con‐
2869 tinue our example, for a bool variable v, ((v==true)) is the
2870 same as ((v==1)) and if a variable named true exists, it is ig‐
2871 nored.
2872 † eval [ arg ... ]
2874 The arguments are read as input to the shell and the resulting
2875 command(s) executed.
2876 † exec [ -c ] [ -a name ] [ arg ... ]
2878 If arg is given, the command specified by the arguments is exe‐
2879 cuted in place of this shell without creating a new process.
2880 The value of the SHLVL environment variable is decreased by one,
2881 unless the shell replaced is a subshell. The -c option causes
2882 the environment to be cleared before applying variable assign‐
2883 ments associated with the exec invocation. The -a option causes
2884 name rather than the first arg, to become argv[0] for the new
2885 process. If arg is not given and only I/O redirections are
2886 given, then this command persistently modifies file descriptors
2887 as in redirect.
2888 † exit [ n ]
2890 Causes the shell to exit with the exit status specified by n.
2891 The value will be the least significant 8 bits of n (if speci‐
2892 fied) or of the exit status of the last command executed. An
2893 end-of-file will also cause the shell to exit, except for an in‐
2894 teractive shell that has the ignoreeof option turned on (see set
2895 below).
2896 †‡ export [ -p ] [ name[=value] ] ...
2898 If name is not given, the names and values of each variable with
2899 the export attribute are printed with the values quoted in a
2900 manner that allows them to be re-input. The export command is
2901 the same as typeset -x except that if you use export within a
2902 function, no local variable is created. The -p option causes
2903 the word export to be inserted before each one. Otherwise, the
2904 given names are marked for automatic export to the environment
2905 of subsequently-executed commands.
2906 false Does nothing, and exits 1. Used with until for infinite loops.
2908 fc [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]
2910 fc -s [ old=new ] [ command ]
2911 The same as hist.
2912 fg [ job... ]
2914 This command is only on systems that support job control. Each
2915 job specified is brought to the foreground and waited for in the
2916 specified order. Otherwise, the current job is brought into the
2917 foreground. See Jobs for a description of the format of job.
2918 ‡ float vname[=value] ...
2920 Declares each vname to be a long floating point number. The
2921 same as typeset -lE.
2922 functions [ -Stux ] [ name ... ]
2924 Lists functions. The same as typeset -f.
2925 getconf [ name [ pathname ] ]
2927 Prints the current value of the configuration parameter given by
2928 name. The configuration parameters are defined by the IEEE
2929 POSIX 1003.1 and IEEE POSIX 1003.2 standards. (See pathconf(2)
2930 and sysconf(3).) The pathname argument is required for parame‐
2931 ters whose value depends on the location in the file system. If
2932 no arguments are given, getconf prints the names and values of
2933 the current configuration parameters. The pathname / is used
2934 for each of the parameters that requires pathname.
2935 getopts [ -a name ] optstring vname [ arg ... ]
2937 Checks arg for legal options. If arg is omitted, the positional
2938 parameters are used. An option argument begins with a + or a -.
2939 An option not beginning with + or - or the argument -- ends the
2940 options. Options beginning with + are only recognized when opt‐
2941 string begins with a +. optstring contains the letters that
2942 getopts recognizes. If a letter is followed by a :, that option
2943 is expected to have an argument. The options can be separated
2944 from the argument by blanks. The option -? causes getopts to
2945 generate a usage message on standard error. The -a argument can
2946 be used to specify the name to use for the usage message, which
2947 defaults to $0.
2948 getopts places the next option letter it finds inside variable
2949 vname each time it is invoked. The option letter will be
2950 prepended with a + when arg begins with a +. The index of the
2951 next arg is stored in OPTIND. The option argument, if any, gets
2952 stored in OPTARG.
2953 A leading : in optstring causes getopts to store the letter of
2954 an invalid option in OPTARG, and to set vname to ? for an un‐
2955 known option and to : when a required option argument is miss‐
2956 ing. Otherwise, getopts prints an error message. The exit sta‐
2957 tus is non-zero when there are no more options.
2958 There is no way to specify any of the options :, +, -, ?, [, and
2959 ]. The option # can only be specified as the first option.
2960 hash [ -r ] [ utility ]
2962 hash displays or modifies the hash table with the locations of
2963 recently used programs. If given no arguments, it lists all com‐
2964 mand/path associations (a.k.a. 'tracked aliases') in the hash
2965 table. Otherwise, hash performs a PATH search for each utility
2966 supplied and adds the result to the hash table. The -r option
2967 empties the hash table. This can also be achieved by resetting
2968 PATH.
2969 hist [ -e ename ] [ -N num ] [ -nlr ] [ first [ last ] ]
2971 hist -s [ old=new ] [ command ]
2972 In the first form, a range of commands from first to last is se‐
2973 lected from the last HISTSIZE commands that were typed at the
2974 terminal. The arguments first and last may be specified as a
2975 number or as a string. A string is used to locate the most re‐
2976 cent command starting with the given string. A negative number
2977 is used as an offset to the current command number. If the -l
2978 option is selected, the commands are listed on standard output.
2979 Otherwise, the editor program ename is invoked on a file con‐
2980 taining these keyboard commands. If ename is not supplied, then
2981 the value of the variable HISTEDIT is used. If HISTEDIT is not
2982 set, then FCEDIT (default /bin/ed) is used as the editor. When
2983 editing is complete, the edited command(s) is executed if the
2984 changes have been saved. If last is not specified, then it will
2985 be set to first. If first is not specified, the default is the
2986 previous command for editing and -16 for listing. The option -r
2987 reverses the order of the commands and the option -n suppresses
2988 command numbers when listing. In the second form, command is
2989 interpreted as first described above and defaults to the last
2990 command executed. The resulting command is executed after the
2991 optional substitution old=new is performed. The option -N
2992 causes hist to start num commands back.
2993 ‡ integer vname[=value] ...
2995 Declares each vname to be a long integer number. The same as
2996 typeset -li.
2997 jobs [ -lnp ] [ job ... ]
2999 Lists information about each given job; or all active jobs if
3000 job is omitted. The -l option lists process IDs in addition to
3001 the normal information. The -n option only displays jobs that
3002 have stopped or exited since last notified. The -p option
3003 causes only the process group to be listed. See Jobs for a de‐
3004 scription of the format of job.
3005 kill [ -s signame ] job ...
3007 kill [ -n signum ] job ...
3008 kill -Ll [ sig ... ]
3009 Sends either the TERM (terminate) signal or the specified signal
3010 to the specified jobs or processes. Signals are either given by
3011 number with the -n option or by name with the -s option (as
3012 given in <signal.h>, stripped of the prefix ``SIG'' with the ex‐
3013 ception that SIGCLD is named CHLD). For backward compatibility,
3014 the n and s can be omitted and the number or name placed immedi‐
3015 ately after the -. If the signal being sent is TERM (terminate)
3016 or HUP (hangup), then the job or process will be sent a CONT
3017 (continue) signal if it is stopped. The argument job can be the
3018 process ID of a process that is not a member of one of the ac‐
3019 tive jobs. See Jobs for a description of the format of job. In
3020 the third form, kill -l or kill -L, if sig is not specified, the
3021 signal names are listed. The -l option lists only the signal
3022 names. The -L option lists each signal name and corresponding
3023 number. Otherwise, for each sig that is a name, the correspond‐
3024 ing signal number is listed. For each sig that is a number, the
3025 signal name corresponding to the least significant 8 bits of sig
3026 is listed.
3027 let arg ...
3029 Each arg is a separate arithmetic expression to be evaluated.
3030 let only recognizes octal numbers starting with 0 when the set
3031 option letoctal is on. See Arithmetic Evaluation above for a
3032 description of arithmetic expression evaluation.
3033 The exit status is 0 if the value of the last expression is non-
3034 zero, and 1 otherwise.
3035 ‡ nameref vname[=refname] ...
3037 Declares each vname to be a variable name reference. The same
3038 as typeset -n.
3039 print [ -CRenprsv ] [ -u unit ] [ -f format ] [ arg ... ]
3041 With no options or with option - or --, each arg is printed on
3042 standard output. The -f option causes the arguments to be
3043 printed as described by printf. In this case, any e, n, r, R
3044 options are ignored. Otherwise, unless the -C, -R, -r, or -v
3045 are specified, the following escape conventions will be applied:
3046 \a The alert character (ASCII 07).
3047 \b The backspace character (ASCII 010).
3048 \c Causes print to end without processing more arguments and
3049 not adding a new-line.
3050 \f The formfeed character (ASCII 014).
3051 \n The newline character (ASCII 012).
3052 \r The carriage return character (ASCII 015).
3053 \t The tab character (ASCII 011).
3054 \v The vertical tab character (ASCII 013).
3055 \E The escape character (ASCII 033).
3056 \\ The backslash character \.
3057 \0x The character defined by the 1, 2, or 3-digit octal
3058 string given by x.
3059 The -R option will print all subsequent arguments and options
3061 other than -n. The -e causes the above escape conventions to be
3062 applied. This is the default behavior. It reverses the effect
3063 of an earlier -r. The -p option causes the arguments to be
3064 written onto the pipe of the process spawned with |& instead of
3065 standard output. The -v option treats each arg as a variable
3066 name and writes the value in the printf %B format. The -C op‐
3067 tion treats each arg as a variable name and writes the value in
3068 the printf %#B format. The -s option causes the arguments to be
3069 written onto the history file instead of standard output. The
3070 -u option can be used to specify a one digit file descriptor
3071 unit number unit on which the output will be placed. The de‐
3072 fault is 1. If the option -n is used, no new-line is added to
3073 the output.
3074 printf [ -v vname ] format [ arg ... ]
3076 The arguments arg are printed on standard output in accordance
3077 with the ANSI C formatting rules associated with the format
3078 string format. If the number of arguments exceeds the number of
3079 format specifications, the format string is reused to format re‐
3080 maining arguments. The following extensions can also be used:
3081 %b A %b format can be used instead of %s to cause escape se‐
3082 quences in the corresponding arg to be expanded as de‐
3083 scribed in print.
3084 %B A %B option causes each of the arguments to be treated as
3085 variable names and the binary value of variable will be
3086 printed. The alternate flag # causes a compound variable
3087 to be output on a single line. This is most useful for
3088 compound variables and variables whose attribute is -b.
3089 %H A %H format can be used instead of %s to cause characters
3090 in arg that are special in HTML and XML to be output as
3091 their entity name. The alternate flag # formats the out‐
3092 put for use as a URI.
3093 %p A %p format will convert the given number to hexadecimal.
3094 %P A %P format can be used instead of %s to cause arg to be
3095 interpreted as an extended regular expression and be
3096 printed as a shell pattern.
3097 %q A %q format can be used instead of %s to cause the re‐
3098 sulting string to be quoted in a manner than can be rein‐
3099 put to the shell. When q is preceded by the alternative
3100 format specifier, #, the string is quoted in manner suit‐
3101 able as a field in a .csv format file.
3102 %(date-format)T
3103 A %(date-format)T format can be used to treat an argument
3104 as a date/time string and to format the date/time accord‐
3105 ing to the date-format.
3106 %Q A %Q format will convert the given number of seconds to
3107 readable time.
3108 %R A %R format can be used instead of %s to cause arg to be
3109 interpreted as a shell pattern and to be printed as an
3110 extended regular expression.
3111 %Z A %Z format will output a byte whose value is 0.
3112 %d The precision field of the %d format can be followed by a
3113 . and the output base. In this case, the # flag charac‐
3114 ter causes base# to be prepended.
3115 # The # flag, when used with the %d format without an out‐
3116 put base, displays the output in powers of 1000 indicated
3117 by one of the following suffixes: k M G T P E, and when
3118 used with the %i format displays the output in powers of
3119 1024 indicated by one of the following suffixes: Ki Mi Gi
3120 Ti Pi Ei.
3121 = The = flag centers the output within the specified field
3122 width.
3123 L The L flag, when used with the %c or %s formats, treats
3124 precision as character width instead of byte count.
3125 , The , flag, when used with the %d or %f formats, sepa‐
3126 rates groups of digits with the grouping delimiter (, on
3127 groups of 3 in the C locale).
3128 The -v option assigns the output directly to a variable instead
3130 of writing it to standard output. This is faster than capturing
3131 the output using a command substitution and avoids the latter's
3132 stripping of final linefeed characters (\n). The vname argument
3133 should be a valid variable name, optionally with one or more ar‐
3134 ray subscripts in square brackets. Note that square brackets
3135 should be quoted to avoid pathname expansion.
3136 pwd [ -LP ]
3139 Outputs the value of the current working directory. The -L op‐
3140 tion is the default; it prints the logical name of the current
3141 directory. If the -P option is given, all symbolic links are
3142 resolved from the name. The last instance of -L or -P on the
3143 command line determines which method is used.
3144 read [ -ACSaprsv ] [ -d delim ] [ -n n ] [ -N n ] [ -t timeout ] [ -u
3146 unit ] [ vname?prompt ] [ vname ... ]
3147 The shell input mechanism. One line is read and is broken up
3148 into fields using the characters in IFS as separators. The es‐
3149 cape character, \, is used to remove any special meaning for the
3150 next character and for line continuation. The first field is
3151 assigned to the first vname, the second field to the second
3152 vname, etc., with leftover fields assigned to the last vname.
3153 If vname is omitted, then REPLY is used as the default vname.
3154 When vname has the binary attribute and -n or -N is specified,
3155 the bytes that are read are stored directly into the variable.
3156 If you append ?prompt to the first vname, then read will display
3157 prompt on standard error before reading if standard input is a
3158 terminal or pipe; the ? should be quoted to protect it from
3159 pathname expansion. The exit status is 0 unless an end-of-file
3160 is encountered or read has timed out. The options for the read
3161 command have meaning as follows:
3162 -A Causes the variable vname to be unset and each field
3163 that is read to be stored in successive elements of the
3164 indexed array vname.
3165 -C Causes the variable vname to be read as a compound vari‐
3166 able. Blanks will be ignored when finding the beginning
3167 open parenthesis.
3168 -N Causes n bytes to be read unless an end-of-file has been
3169 encountered or the read times out because of the -t op‐
3170 tion.
3171 -S Causes the line to be treated like a record in a .csv
3172 format file so that double quotes can be used to allow
3173 the delimiter character and the new-line character to
3174 appear within a field.
3175 -a Same as -A.
3176 -d Causes the read to continue to the first character of
3177 delim instead of the newline control character.
3178 -n Causes at most n bytes to be read instead of a full
3179 line, but will return when reading from a slow device as
3180 soon as any characters have been read.
3181 -p Input is read from the current co-process spawned by the
3182 shell using ⎪&. An end-of-file causes read to discon‐
3183 nect the co-process so that another can be created.
3184 -r Raw mode. The \ character is not treated specially.
3185 -s The input will be saved as a command in the history
3186 file.
3187 -t Used to specify a timeout in seconds when reading from a
3188 terminal or pipe.
3189 -u This option can be used to specify a one-digit file de‐
3190 scriptor unit unit to read from. The file descriptor
3191 can be opened with the exec or redirect built-in com‐
3192 mand. If unit is p, input is read from the current co-
3193 process as with the -p option. The default value of
3194 unit is 0.
3195 -v The value of the first vname will be used as a default
3196 value when reading from a terminal device.
3197 †‡ readonly [ -p ] [ vname[=value] ] ...
3199 If vname is not given, the names and values of each variable
3200 with the read-only attribute is printed with the values quoted
3201 in a manner that allows them to be re-input. The -p option
3202 causes the word readonly to be inserted before each one. Other‐
3203 wise, the given vnames are marked read-only and these names can‐
3204 not be changed by subsequent assignment. Unlike typeset -r ,
3205 readonly does not create a function-local scope and the given
3206 vnames are marked globally read-only by default. When defining
3207 a type, if the value of a read-only subvariable is not defined,
3208 the value is required when creating each instance.
3209 redirect
3211 This command only accepts input/output redirections. It can
3212 open and close files and modify file descriptors from 0 to 9 as
3213 specified by the input/output redirection list (see the In‐
3214 put/Output section above), with the difference that the effect
3215 persists past the execution of the redirect command. When in‐
3216 voking another program, file descriptors greater than 2 that
3217 were opened with this mechanism are only passed on if they are
3218 explicitly redirected to themselves as part of the invocation
3219 (e.g. 4>&4) or if the posix option is set.
3220 † return [ n ]
3222 Causes a shell function, dot script (see . and source), or pro‐
3223 file script to return to the invoking shell environment with the
3224 exit status specified by n. This status value can use the full
3225 signed integer range as shown by the commands getconf INT_MIN
3226 and getconf INT_MAX. A value outside that range will produce a
3227 warning and an exit status of 128. If n is omitted, then the
3228 value of $? is assumed, i.e., the exit status of the last com‐
3229 mand executed is passed on. If return is invoked while not in a
3230 function, dot script, or profile script, then it behaves the
3231 same as exit.
3232 † set [ ±BCGHabefhkmnprstuvx ] [ ±o [ option ] ] ... [ ±A vname ] [
3234 arg ... ]
3235 The options for this command have meaning as follows:
3236 -A Array assignment. Unset the variable vname and assign
3237 values sequentially from the arg list. If +A is used,
3238 the variable vname is not unset first.
3239 -B Enable brace group expansion. On by default, except if
3240 ksh is invoked as sh or rsh.
3241 -C Prevents redirection > from truncating existing files.
3242 Files that are created are opened with the O_EXCL mode.
3243 Requires >| to truncate a file when turned on.
3244 -G Enables recursive pathname expansion. This adds the
3245 double-star pattern ** to the pathname expansion (see
3246 Pathname Expansion above). By itself, it matches the
3247 recursive contents of the current directory, which is to
3248 say, all files and directories in the current directory
3249 and in all its subdirectories, sub-subdirectories, and
3250 so on. If the pathname pattern ends in **/, only direc‐
3251 tories and subdirectories are matched, including sym‐
3252 bolic links that point to directories. A prefixed di‐
3253 rectory name is not included in the results unless that
3254 directory was itself found by a pattern. For example,
3255 dir/** matches the recursive contents of dir but not dir
3256 itself, whereas di[r]/** matches both dir itself and the
3257 recursive contents of dir. Symbolic links to non-direc‐
3258 tories are not followed. Symbolic links to directories
3259 are followed if they are specified literally or match a
3260 pattern as described under Pathname Expansion, but not
3261 if they result from a double-star pattern.
3262 -H Enable !-style history expansion similar to csh(1). See
3263 History Expansion above.
3264 -a All variables that are assigned a value while this op‐
3265 tion is on are automatically exported, unless they have
3266 a dot in their name. Variables created in namespaces
3267 declared with the namespace keyword (see Name Spaces
3268 above) are only exported while their name space is ac‐
3269 tive.
3270 -b Prints job completion messages as soon as a background
3271 job changes state rather than waiting for the next
3272 prompt. If one of the shell line editors is in use (see
3273 In-line Editing Options above), the completion message
3274 is inserted directly above the command line being typed.
3275 -e Unless contained in a || or && command, or the command
3276 following an if while or until command or in the pipe‐
3277 line following !, if a command has a non-zero exit sta‐
3278 tus, execute the ERR trap, if set, and exit. This mode
3279 is disabled while reading profiles.
3280 -f Disables pathname expansion.
3281 -h Obsolete; no effect.
3282 -k All variable assignment arguments are placed in the en‐
3283 vironment for a command, not just those that precede the
3284 command name.
3285 -m Background jobs will run in a separate process group and
3286 a line will print upon completion. The exit status of
3287 background jobs is reported in a completion message. A
3288 pipeline will not terminate until all component commands
3289 of the pipeline have terminated. On systems with job
3290 control, this option is turned on automatically for in‐
3291 teractive shells.
3292 -n Read commands and check them for syntax errors, but do
3293 not execute them. Ignored for interactive shells.
3294 -o The following argument can be one of the following op‐
3295 tion names:
3296 allexport
3297 Same as -a.
3298 backslashctrl
3299 The backslash character \ escapes the next con‐
3300 trol character in the emacs built-in editor and
3301 the next erase or kill character in the vi
3302 built-in editor. On by default.
3303 bgnice All background jobs are run at a lower priority.
3304 This is the default mode.
3305 braceexpand
3306 Same as -B.
3307 emacs Puts you in an emacs style in-line editor for
3308 command entry.
3309 errexit Same as -e.
3310 functrace
3311 Causes the -x option's state and the DEBUG trap
3312 action to be inherited by functions defined us‐
3313 ing the function keyword (see Functions above)
3314 instead of being reset to default. Changes made
3315 to them within the function do not propagate
3316 back to the parent scope. Similarly, this op‐
3317 tion also causes the DEBUG trap action to be in‐
3318 herited by subshells.
3319 globcasedetect
3320 When this option is turned on, globbing (see
3321 Pathname Expansion above) and file name listing
3322 and completion (see In-line Editing Options
3323 above) automatically become case-insensitive on
3324 file systems where the difference between upper-
3325 and lowercase is ignored for file names. This is
3326 transparently determined for each directory, so
3327 a path pattern that spans multiple file systems
3328 can be part case-sensitive and part case-insen‐
3329 sitive. In more precise terms, each slash-sepa‐
3330 rated path name component pattern p is treated
3331 as ~(i:p) if its parent directory exists on a
3332 case-insensitive file system. This option is
3333 only present on operating systems that support
3334 case-insensitive file systems.
3335 globstar
3336 Same as -G.
3337 gmacs Puts you in a gmacs style in-line editor for
3338 command entry.
3339 histexpand
3340 Same as -H.
3341 histreedit
3342 If a history expansion (see -H) fails, the com‐
3343 mand line is reloaded into the next prompt's
3344 edit buffer, allowing corrections.
3345 histverify
3346 The results of a history expansion (see -H) are
3347 not immediately executed. Instead, the expanded
3348 line is loaded into the next prompt's edit buf‐
3349 fer, allowing further changes.
3350 ignoreeof
3351 An interactive shell will not exit on end-of-
3352 file. The command exit must be used.
3353 keyword Same as -k.
3354 letoctal
3355 The let command allows octal numbers starting
3356 with 0. On by default if ksh is invoked as sh
3357 or rsh.
3358 markdirs
3359 All directory names resulting from pathname ex‐
3360 pansion have a trailing / appended.
3361 monitor Same as -m.
3362 multiline
3363 The built-in editors will use multiple lines on
3364 the screen for lines that are longer than the
3365 width of the screen. This may not work for all
3366 terminals.
3367 noclobber
3368 Same as -C.
3369 noexec Same as -n.
3370 noglob Same as -f.
3371 nolog Obsolete; has no effect.
3372 notify Same as -b.
3373 nounset Same as -u.
3374 pipefail
3375 The exit status of the entire pipeline will be
3376 that of the last component command that exited
3377 with a non-zero exit status, or zero if no com‐
3378 mand exited with a non-zero exit status. The
3379 shell will wait for all component commands of
3380 the pipeline to terminate, instead of only wait‐
3381 ing for the last component command.
3382 posix Enables the POSIX standard mode for maximum com‐
3383 patibility with other compliant shells. At the
3384 moment that the posix option is turned on, it
3385 also turns on letoctal and turns off -B/braceex‐
3386 pand; the reverse is done when posix is turned
3387 back off. (These options can still be controlled
3388 independently in between.) Furthermore, the
3389 posix option is automatically turned on upon in‐
3390 vocation if the shell is invoked as sh or rsh,
3391 or if -o posix or --posix is specified on the
3392 shell invocation command line, or when executing
3393 scripts without a #! path with this option ac‐
3394 tive in the invoking shell. In that case, the
3395 invoked shell will not import type attributes
3396 for variables (such as integer or left/right
3397 justify) from the environment.
3398 In addition, while on, the posix option
3399 • disables exporting variable type attributes
3400 to the environment for other ksh processes to
3401 import;
3402 • if the -B/braceexpand option is turned back
3403 on, disallows brace expansion on the results
3404 of unquoted expansions;
3405 • disables the special handling of repeated
3406 isspace class characters in the IFS variable;
3407 • causes file descriptors > 2 to be left open
3408 when invoking another program;
3409 • disables the &> redirection shorthand;
3410 • disables fast filescan loops of type while
3411 inputredirection ;do list ;done;
3412 • makes the <> redirection operator default to
3413 redirecting standard input if no file de‐
3414 scriptor number precedes it;
3415 • causes the shell to use a standard UNIX
3416 pipe(2) instead of a socketpair(2) to connect
3417 commands in a pipeline (when reading directly
3418 from a pipeline, the <#pattern and <##pattern
3419 redirection operators will not work and the
3420 -n option to the read built-in will not re‐
3421 turn early when reading from a slow device);
3422 • disables the special floating point constants
3423 Inf and NaN in arithmetic evaluation so that,
3424 e.g., $((inf)) and $((nan)) refer to the
3425 variables by those names;
3426 • enables the recognition of a leading zero as
3427 introducing an octal number in all arithmetic
3428 evaluation contexts, except in the let built-
3429 in while letoctal is off;
3430 • disables zero-padding of seconds in the out‐
3431 put of the time and times built-ins;
3432 • stops the . command (but not source) from
3433 looking up functions defined with the func‐
3434 tion syntax;
3435 • disables the recognition of unexpanded shell
3436 arithmetic expressions in the numerical com‐
3437 parison operators -eq, -ne, -gt, -ge, -lt and
3438 -le of the test/[ built-in command, causing
3439 them to accept only decimal numbers as oper‐
3440 ands;
3441 • changes the test/[ built-in command to make
3442 its deprecated expr1 -a expr2 and expr1 -o
3443 expr2 operators work even if expr1 equals "!"
3444 or "(" (which means the nonstandard unary -a
3445 file and -o option operators cannot be di‐
3446 rectly negated using ! or wrapped in paren‐
3447 theses); and
3448 • disables a hack that makes test -t ([ -t ])
3449 equivalent to test -t 1 ([ -t 1 ]).
3450 privileged
3451 Same as -p.
3452 showme When enabled, simple commands or pipelines pre‐
3453 ceded by a semicolon (;) will be displayed as if
3454 the xtrace option were enabled but will not be
3455 executed. Otherwise, the leading ; will be ig‐
3456 nored.
3457 trackall
3458 Same as -h.
3459 verbose Same as -v.
3460 vi Puts you in insert mode of a vi style in-line
3461 editor until you hit the escape character 033.
3462 This puts you in control mode. A return sends
3463 the line.
3464 viraw Each character is processed as it is typed in vi
3465 mode. The shell may have been compiled to force
3466 this option on at all times. Otherwise, canoni‐
3467 cal processing (line-by-line input) is initially
3468 enabled and the command line will be echoed
3469 again if the speed is 1200 baud or greater and
3470 it contains any control characters or less than
3471 one second has elapsed since the prompt was
3472 printed. The ESC character terminates canonical
3473 processing for the remainder of the command and
3474 the user can then modify the command line. This
3475 scheme has the advantages of canonical process‐
3476 ing with the type-ahead echoing of raw mode. If
3477 the viraw option is set, the terminal will al‐
3478 ways have canonical processing disabled. This
3479 mode is implicit for systems that do not support
3480 two alternate end of line delimiters, and may be
3481 helpful for certain terminals.
3482 xtrace Same as -x.
3483 If no option name is supplied, then the current option
3485 settings are printed.
3486 -p Disables processing of the $HOME/.profile file and uses
3488 the file /etc/suid_profile instead of the ENV file.
3489 This mode is on whenever the effective UID (GID) is not
3490 equal to the real UID (GID). Turning this off causes
3491 the effective UID and GID to be set to the real UID and
3492 GID.
3493 -r Enables the restricted shell. This option cannot be un‐
3494 set once set.
3495 -s Sort the positional parameters lexicographically.
3496 -t (Obsolete). Exit after reading and executing one com‐
3497 mand.
3498 -u Treat unset parameters as an error when substituting.
3499 $@ and $* are exempt.
3500 -v Print shell input lines as they are read.
3501 -x Print commands and their arguments as they are executed.
3502 -- Do not change any of the options; useful in setting $1
3503 to a value beginning with -. If no arguments follow
3504 this option then the positional parameters are unset.
3505 As an obsolete feature, if the first arg is - then the -x and -v
3507 options are turned off and the next arg is treated as the first
3508 argument. Using + rather than - causes these options to be
3509 turned off. These options can also be used upon invocation of
3510 the shell. The current set of options may be found in $-. Un‐
3511 less -A is specified, the remaining arguments are positional pa‐
3512 rameters and are assigned, in order, to $1 $2 .... If no argu‐
3513 ments are given, then the names and values of all variables are
3514 printed on the standard output.
3515 † shift [ n ]
3517 The positional parameters from $n+1 ... are renamed $1 ... ,
3518 default n is 1. The parameter n can be any arithmetic expres‐
3519 sion that evaluates to a non-negative number less than or equal
3520 to $#.
3521 sleep [ -s ] duration
3523 Suspends execution for the number of decimal seconds or frac‐
3524 tions of a second given by duration. duration can be an inte‐
3525 ger, floating point value or ISO 8601 duration specifying the
3526 length of time to sleep. The option -s causes the sleep builtin
3527 to terminate when it receives any signal. If duration is not
3528 specified in conjunction with -s, sleep will wait for a signal
3529 indefinitely.
3530 source name [ arg ... ]
3532 Same as ., except it is not treated as a special built-in com‐
3533 mand.
3534 stop job ...
3536 Sends a SIGSTOP signal to one or more processes specified by
3537 job, suspending them until they receive SIGCONT. The same as
3538 kill -s STOP.
3539 suspend
3541 Sends a SIGSTOP signal to the main shell process, suspending the
3542 script or child shell session until it receives SIGCONT (for in‐
3543 stance, when typing fg in the parent shell). Equivalent to
3544 kill -s STOP "$$", except that it accepts no operands and re‐
3545 fuses to suspend a login shell.
3546 test expression
3548 The test and [ commands execute conditional expressions similar
3549 to those specified for the [[ compound command under Conditional
3550 Expressions above, but with several important differences. The
3551 =, == and != operators test for string (in)equality without pat‐
3552 tern matching; == is nonstandard and unportable. The && and ||
3553 operators are not available. Instead, the -a and -o binary oper‐
3554 ators can be used, but they are fraught with pitfalls due to
3555 grammatical ambiguities and therefore deprecated in favor of in‐
3556 voking separate test commands. Most importantly, as test and [
3557 are simple regular commands, field splitting and pathname expan‐
3558 sion are performed on all their arguments and all aspects of
3559 regular shell grammar (such as redirection) remain active. This
3560 is usually harmful, so care must be taken to quote arguments and
3561 expansions to avoid this. To avoid the many pitfalls arising
3562 from these issues, the [[ compound command should be used in‐
3563 stead. The primary purpose of the test and [ commands is compat‐
3564 ibility with other shells that lack [[.
3565 The test/[ command does not parse options except if there are
3567 two arguments and the second is --. To access the inline docu‐
3568 mentation with an option such as --man, you need one of the
3569 forms test --man -- or [ --man -- ].
3570 times Displays the accumulated user and system CPU times, one line
3572 with the times used by the shell and another with those used by
3573 all of the shell's child processes. No options are supported.
3574 Seconds are zero-padded unless the posix shell option is on.
3575 † trap [ -p ] [ action ] [ sig ] ...
3577 The -p option causes the trap action associated with each trap
3578 as specified by the arguments to be printed with appropriate
3579 quoting. Otherwise, action will be processed as if it were an
3580 argument to eval when the shell receives signal(s) sig. Each
3581 sig can be given as a number or as the name of the signal. Trap
3582 commands are executed in order of signal number. Any attempt to
3583 set a trap on a signal that was ignored on entry to the current
3584 shell is ineffective. If action is omitted and the first sig is
3585 a number, or if action is -, then the trap(s) for each sig are
3586 reset to their original values. If action is the empty string,
3587 then this signal is ignored by the shell and by the commands it
3588 invokes. If sig is ERR then action will be executed whenever a
3589 command has a non-zero exit status. If sig is DEBUG then action
3590 will be executed before each command. The variable .sh.command
3591 will contain the current command line when action is running, in
3592 the same format as the output generated by the xtrace option
3593 (minus the preceding PS4 prompt). If the exit status of the
3594 trap is 2 the command will not be executed. If the exit status
3595 of the trap is 255 and inside a function or a dot script, the
3596 function or dot script will return. If sig is 0 or EXIT and the
3597 trap statement is executed inside the body of a function defined
3598 with the function name syntax, then the command action is exe‐
3599 cuted after the function completes. If sig is 0 or EXIT for a
3600 trap set outside any function then the command action is exe‐
3601 cuted on exit from the shell. If sig is KEYBD, then action will
3602 be executed whenever a key is read while in emacs, gmacs, or vi
3603 mode. The trap command with no arguments prints a list of com‐
3604 mands associated with each signal number.
3605 An exit or return without an argument in a trap action will preserve
3607 the exit status of the command that invoked the trap.
3608 true Does nothing, and exits 0. Used with while for infinite loops.
3610 type [ -afpPqt ] name ...
3612 The same as whence -v.
3613 †‡ typeset [ ±ACHSbflmnprstux ] [ ±EFLRXZi[n] ] [ +-M [ mapname ] ]
3615 [ -T [ tname=(assign_list) ] ] [ -h str ] [ -a [type] ] [ vname[=value
3616 ] ] ...
3617 Sets attributes and values for shell variables and functions.
3618 When invoked inside a function defined with the function name
3619 syntax, a new instance of the variable vname is created, and the
3620 variable's value and type are restored when the function com‐
3621 pletes. The following list of attributes may be specified:
3622 -A Declares vname to be an associative array. Subscripts
3623 are strings rather than arithmetic expressions.
3624 -C Causes each vname to be a compound variable. If value
3625 names a compound variable, it is copied into vname. Oth‐
3626 erwise, the empty compound value is assigned to vname.
3627 -a Declares vname to be an indexed array. If type is speci‐
3628 fied, it must be the name of an enumeration type created
3629 with the enum command and it allows enumeration constants
3630 to be used as subscripts.
3631 -E Declares vname to be a double precision floating point
3632 number. If n is non-zero, it defines the number of sig‐
3633 nificant figures that are used when expanding vname.
3634 Otherwise, ten significant figures will be used.
3635 -F Declares vname to be a double precision floating point
3636 number. If n is non-zero, it defines the number of
3637 places after the decimal point that are used when expand‐
3638 ing vname. Otherwise ten places after the decimal point
3639 will be used.
3640 -H This option provides UNIX to host-name file mapping on
3641 non-UNIX machines.
3642 -L Left justify and remove leading blanks from value. If n
3643 is non-zero, it defines the width of the field, otherwise
3644 it is determined by the width of the value of first as‐
3645 signment. When the variable is assigned to, it is filled
3646 on the right with blanks or truncated, if necessary, to
3647 fit into the field. The -R option is turned off.
3648 -M Use the character mapping mapping defined by wctrans(3).
3649 such as tolower and toupper when assigning a value to
3650 each of the specified operands. When mapping is speci‐
3651 fied and there are not operands, all variables that use
3652 this mapping are written to standard output. When map‐
3653 ping is omitted and there are no operands, all mapped
3654 variables are written to standard output.
3655 -R Right justify and fill with leading blanks. If n is non-
3656 zero, it defines the width of the field, otherwise it is
3657 determined by the width of the value of first assignment.
3658 The field is left filled with blanks or truncated from
3659 the end if the variable is reassigned. The -L option is
3660 turned off.
3661 -S When used within the assign_list of a type definition, it
3662 causes the specified subvariable to be shared by all in‐
3663 stances of the type. When used inside a function defined
3664 with the function reserved word, the specified variables
3665 will have function static scope. Otherwise, the variable
3666 is unset prior to processing the assignment list.
3667 -T If followed by tname, it creates a type named by tname
3668 using the compound assignment assign_list to tname. Oth‐
3669 erwise, it writes all the type definitions to standard
3670 output.
3671 -X Declares vname to be a double precision floating point
3672 number and expands using the %a format of ISO-C99. If n
3673 is non-zero, it defines the number of hex digits after
3674 the radix point that is used when expanding vname. The
3675 default is 10.
3676 -Z Right justify and fill with leading zeros if the first
3677 non-blank character is a digit and the -L option has not
3678 been set. Remove leading zeros if the -L option is also
3679 set. If n is non-zero, it defines the width of the
3680 field, otherwise it is determined by the width of the
3681 value of first assignment.
3682 -f The names refer to function names rather than variable
3683 names. No assignments can be made and the only other
3684 valid options are -S, -t, -u and -x. The -S can be used
3685 with discipline functions defined in a type to indicate
3686 that the function is static. For a static function, the
3687 same method will be used by all instances of that type no
3688 matter which instance references it. In addition, it can
3689 only use value of variables from the original type defi‐
3690 nition. These discipline functions cannot be redefined
3691 in any type instance. The -t option turns on execution
3692 tracing for this function. The -u option causes this
3693 function to be marked undefined. The FPATH variable will
3694 be searched to find the function definition when the
3695 function is referenced. If no options other than -f is
3696 specified, then the function definition will be displayed
3697 on standard output. If +f is specified, then a line con‐
3698 taining the function name followed by a shell comment
3699 containing the line number and path name of the file
3700 where this function was defined, if any, is displayed.
3701 The exit status can be used to determine whether the
3702 function is defined so that typeset -f .sh.math.name will
3703 return 0 when math function name is defined and non-zero
3704 otherwise.
3705 -b The variable can hold any number of bytes of data. The
3706 data can be text or binary. The value is represented by
3707 the base64 encoding of the data. If -Z is also speci‐
3708 fied, the size in bytes of the data in the buffer will be
3709 determined by the size associated with the -Z. If the
3710 base64 string assigned results in more data, it will be
3711 truncated. Otherwise, it will be filled with bytes whose
3712 value is zero. The printf format %B can be used to out‐
3713 put the actual data in this buffer instead of the base64
3714 encoding of the data.
3715 -g Forces variables to be created or modified at the global
3716 scope, even when typeset is executed in a function de‐
3717 fined by the function name syntax (see Functions above)
3718 or in a name space (see Name Spaces above).
3719 -h Used within type definitions to add information when gen‐
3720 erating information about the subvariable on the man
3721 page. It is ignored when used outside of a type defini‐
3722 tion. When used with -f the information is associated
3723 with the corresponding discipline function.
3724 -i Declares vname to be represented internally as integer.
3725 The right hand side of an assignment is evaluated as an
3726 arithmetic expression when assigning to an integer. If n
3727 is non-zero, it defines the output arithmetic base, oth‐
3728 erwise the output base will be ten.
3729 -l Used with -i, -E or -F, to indicate long integer, or long
3730 float. Otherwise, all uppercase characters are converted
3731 to lowercase. The uppercase option, -u, is turned off.
3732 Equivalent to -M tolower .
3733 -m Moves or renames the variable. The value is the name of
3734 a variable whose value will be moved to vname. The orig‐
3735 inal variable will be unset. Cannot be used with any
3736 other options.
3737 -n Declares vname to be a reference to the variable whose
3738 name is defined by the value of variable vname. This is
3739 usually used to reference a variable inside a function
3740 whose name has been passed as an argument. Cannot be
3741 used with other options except -g.
3742 -p The name, attributes and values for the given vnames are
3743 written on standard output in a form that can be used as
3744 shell input. If +p is specified, then the values are not
3745 displayed.
3746 -r The given vnames are marked read-only and these names
3747 cannot be changed by subsequent assignment.
3748 -s When given along with -i, restricts integer size to
3749 short.
3750 -t Tags the variables. Tags are user definable and have no
3751 special meaning to the shell.
3752 -u When given along with -i, specifies unsigned integer.
3753 Otherwise, all lowercase characters are converted to up‐
3754 percase. The lowercase option, -l, is turned off.
3755 Equivalent to -M toupper .
3756 -x The given vnames are marked for automatic export to the
3757 environment of subsequently-executed commands. Variables
3758 whose names contain a . cannot be exported.
3759 The -i, -F, -E, and -X options cannot be specified along with
3761 -R, -L, or -Z. The -b option cannot be specified along with -L,
3762 -u, or -l. The -f, -m, -n, and -T options cannot be used to‐
3763 gether with any other option.
3764 Using + rather than - causes these options to be turned off. If
3766 no vname arguments are given, a list of vnames (and optionally
3767 the values) of the variables is printed. (Using + rather than -
3768 keeps the values from being printed.) The -p option causes
3769 typeset followed by the option letters to be printed before each
3770 name rather than the names of the options. If any option other
3771 than -p is given, only those variables which have all of the
3772 given options are printed. Otherwise, the vnames and attributes
3773 of all variables that have attributes are printed.
3774 ulimit [ -HSaMctdfkxlqenVuPpmrRbiswTv ] [ limit ]
3776 Set or display a resource limit. The available resource limits
3777 are listed below. Many systems do not support one or more of
3778 these limits. The limit for a specified resource is set when
3779 limit is specified. The value of limit can be a number in the
3780 unit specified below with each resource, or the value unlimited.
3781 The -H and -S options specify whether the hard limit or the soft
3782 limit for the given resource is set. A hard limit cannot be in‐
3783 creased once it is set. A soft limit can be increased up to the
3784 value of the hard limit. If neither the H nor S option is spec‐
3785 ified, the limit applies to both. The current resource limit is
3786 printed when limit is omitted. In this case, the soft limit is
3787 printed unless H is specified. When more than one resource is
3788 specified, then the limit name and unit is printed before the
3789 value.
3790 -a Lists all of the current resource limits.
3791 -b The socket buffer size in bytes.
3792 -c The number of 512-byte blocks on the size of core dumps.
3793 -d The number of K-bytes on the size of the data area.
3794 -e The scheduling priority.
3795 -f The number of 512-byte blocks on files that can be writ‐
3796 ten by the current process or by child processes (files
3797 of any size may be read).
3798 -i The signal queue size.
3799 -k The max number of kqueues created by the current user.
3800 -l The locked address space in K-bytes.
3801 -M The address space limit in K-bytes.
3802 -m The number of K-bytes on the size of physical memory.
3803 -n The number of file descriptors plus 1.
3804 -P The max number of pseudo-terminals created by the current
3805 user.
3806 -p The number of 512-byte blocks for pipe buffering.
3807 -q The message queue size in K-bytes.
3808 -R The max time a real-time process can run before blocking,
3809 in microseconds. If this limit is exceeded the process
3810 is sent a SIGXCPU signal.
3811 -r The max real-time priority.
3812 -s The number of K-bytes on the size of the stack area.
3813 -T The number of threads.
3814 -t The number of CPU seconds to be used by each process.
3815 -u The number of processes.
3816 -V The number of open vnode monitors.
3817 -v The number of K-bytes for virtual memory.
3818 -w The swap size in K-bytes.
3819 -x The number of file locks.
3820 If no option is given, -f is assumed.
3822 umask [ -S ] [ mask ]
3824 The user file-creation mask is set to mask (see umask(2)). mask
3825 can either be an octal number or a symbolic value as described
3826 in chmod(1). If a symbolic value is given, the new umask value
3827 is the complement of the result of applying mask to the comple‐
3828 ment of the previous umask value. If mask is omitted, the cur‐
3829 rent value of the mask is printed. The -S option causes the
3830 mode to be printed as a symbolic value. Otherwise, the mask is
3831 printed in octal.
3832 unalias [ -a ] name ...
3834 The aliases given by the list of names are removed from the
3835 alias list. The -a option causes all the aliases to be unset.
3836 † unset [ -fnv ] vname ...
3838 The variables given by the list of vnames are unassigned, i.e.,
3839 except for subvariables within a type, their values and at‐
3840 tributes are erased. For subvariables of a type, the values are
3841 reset to the default value from the type definition. Readonly
3842 variables cannot be unset. If the -f option is set, then the
3843 names refer to function names. If the -v option is set, then
3844 the names refer to variable names. The -f option overrides -v.
3845 If -n is set and name is a name reference, then name will be un‐
3846 set rather than the variable that it references. The default is
3847 equivalent to -v. Unsetting LINENO, MAILCHECK, OPTARG, OPTIND,
3848 RANDOM, SECONDS, TMOUT, and _ removes their special meaning even
3849 if they are subsequently assigned to.
3850 wait [ job ... ]
3852 Wait for the specified job and report its termination status.
3853 If job is not given, then all currently active child processes
3854 are waited for. The exit status from this command is that of
3855 the last process waited for if job is specified; otherwise it is
3856 zero. See Jobs for a description of the format of job.
3857 whence [ -afpPqtv ] name ...
3859 For each name, indicate how it would be interpreted if used as a
3860 command name.
3861 The -v option produces a more verbose report. The -f option
3862 skips the search for functions. The -p and -P options do a path
3863 search for name even if name is an alias, a function, or a re‐
3864 served word. Both of these options turn off the -v option. The
3865 -q option causes whence to enter quiet mode. whence will return
3866 zero if all arguments are built-ins, functions, or are programs
3867 found on the path. The -t option only outputs the type of the
3868 given command. Like -p and -P, -t will turn off the -v option.
3869 The -a option is similar to the -v option but causes all inter‐
3870 pretations of the given name to be reported.
3871 Invocation.
3873 If the shell is invoked by exec(2), initialization depends on argument
3874 zero ($0) as follows. If the first character of $0 is -, or the -l op‐
3875 tion is given on the invocation command line, then the shell is assumed
3876 to be a login shell. If the basename of the command path in $0 is rsh,
3877 rksh, or krsh, then the shell becomes restricted. If the basename is
3878 sh or rsh, or the -o posix option is given on the invocation command
3879 line, then the shell is initialized in full POSIX compliance mode (see
3880 the set builtin command above for more information). After this, if
3881 the shell was assumed to be a login shell, commands are read from
3882 /etc/profile and then from $HOME/.profile if it exists. Alternatively,
3883 the option -l causes the shell to be treated as a login shell. Next,
3884 for interactive shells, commands are read from the file named by ENV if
3885 the file exists, its name being determined by performing parameter ex‐
3886 pansion, command substitution, and arithmetic expansion on the value of
3887 that environment variable. If the -s option is not present and arg and
3888 a file by the name of arg exists, then it reads and executes this
3889 script. Otherwise, if the first arg does not contain a /, a path
3890 search is performed on the first arg to determine the name of the
3891 script to execute. The script arg must have execute permission and any
3892 setuid and setgid settings will be ignored. If the script is not found
3893 on the path, arg is processed as if it named a built-in command or
3894 function. Commands are then read as described below; the following op‐
3895 tions are interpreted by the shell when it is invoked:
3896 -D A list of all double quoted strings that are preceded by a $
3898 will be printed on standard output and the shell will exit.
3899 This set of strings will be subject to language translation
3900 when the locale is not C or POSIX. No commands will be exe‐
3901 cuted.
3902 -E or -o rc or --rc
3904 Read the file named by the ENV variable or by $HOME/.kshrc if
3905 not defined after the profiles. On by default for interactive
3906 shells. Use +E, +o rc or --norc to turn off.
3907 -c Read and execute a script from the first arg instead of a file.
3909 The second arg, if present, becomes that script's command name
3910 ($0). Any third and further args become positional parameters
3911 starting at $1.
3912 -s Read and execute a script from standard input instead of a
3914 file. The command name ($0) cannot be set. Any args become
3915 the positional parameters starting at $1. This option is
3916 forced on if no arg is given and is ignored if -c is also spec‐
3917 ified.
3918 -i or -o interactive or --interactive
3920 If the -i option is present or if the shell's standard input
3921 and standard error are attached to a terminal (as told by tcge‐
3922 tattr(3)), then this shell is interactive. In this case TERM
3923 is ignored (so that kill 0 does not kill an interactive shell)
3924 and INTR is caught and ignored (so that wait is interruptible).
3925 In all cases, QUIT is ignored by the shell.
3926 -r or -o restricted or --restricted
3928 If the -r option is present, the shell is a restricted shell.
3929 The remaining options and arguments are described under the set command
3931 above. An optional - as the first argument is ignored.
3932 Rksh Only.
3934 Rksh is used to set up login names and execution environments whose ca‐
3935 pabilities are more controlled than those of the standard shell. The
3936 actions of rksh are identical to those of ksh, except that the follow‐
3937 ing are disallowed:
3938 • unsetting the restricted option
3940 • changing directory (see cd(1))
3942 • setting or unsetting the value or attributes of SHELL,
3944 ENV, FPATH, or PATH
3945 • specifying path or command names containing /
3947 • redirecting output (>, >|, <>, and >>)
3949 • adding or deleting built-in commands
3951 • using command -p to invoke a command
3953 The restrictions above are enforced after .profile and the ENV files
3955 are interpreted.
3956 When a command to be executed is found to be a shell procedure, rksh
3958 invokes ksh to execute it. Thus, it is possible to provide to the end-
3959 user shell procedures that have access to the full power of the stan‐
3960 dard shell, while imposing a limited menu of commands; this scheme as‐
3961 sumes that the end-user does not have write and execute permissions in
3962 the same directory.
3963 The net effect of these rules is that the writer of the .profile has
3965 complete control over user actions, by performing guaranteed setup ac‐
3966 tions and leaving the user in an appropriate directory (probably not
3967 the login directory).
3968 The system administrator often sets up a directory of commands (e.g.,
3970 /usr/rbin) that can be safely invoked by rksh.
3971
3973 Errors detected by the shell, such as syntax errors, cause the shell to
3974 return a non-zero exit status. If the shell is being used non-interac‐
3975 tively, then execution of the shell file is abandoned unless the error
3976 occurs inside a subshell in which case the subshell is abandoned. Oth‐
3977 erwise, the shell returns the exit status of the last command executed
3978 (see also the exit command above). Run time errors detected by the
3979 shell are reported by printing the command or function name and the er‐
3980 ror condition. If the line number that the error occurred on is
3981 greater than one, then the line number is also printed in square brack‐
3982 ets ([]) after the command or function name.
3983
3985 /etc/profile
3986 The system wide initialization file, executed for login shells.
3987 $HOME/.profile
3989 The personal initialization file, executed for login shells af‐
3990 ter /etc/profile.
3991 $HOME/.kshrc
3993 Default personal initialization file, executed for interactive
3994 shells when ENV is not set.
3995 /etc/suid_profile
3997 Alternative initialization file, executed instead of the per‐
3998 sonal initialization file when the real and effective user or
3999 group ID do not match.
4000 /dev/null
4002 The null device.
4003
4005 cat(1), cd(1), chmod(1), cut(1), date(1), echo(1), emacs(1), env(1),
4006 gmacs(1), grep(1), stty(1), test(1), umask(1), vi(1), dup(2), exec(2),
4007 fork(2), getpwnam(3), ioctl(2), lseek(2), paste(1), pathconf(2),
4008 pipe(2), sysconf(3), umask(2), ulimit(2), wait(2), strftime(3), wc‐
4009 trans(3), rand(3), a.out(5), profile(5), environ(7).
4010 Morris I. Bolsky and David G. Korn, The New KornShell Command and Pro‐
4012 gramming Language, Prentice Hall, 1995.
4013 POSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC
4015 9945-2, IEEE, 1993.
4016
4018 If a command is executed, and then a command with the same name is in‐
4019 stalled in a directory in the search path before the directory where
4020 the original command was found, the shell will continue to exec the
4021 original command. Use the hash command or the -t option of the alias
4022 command to correct this situation.
4023 Using the hist built-in command within a compound command will cause
4025 the whole command to disappear from the history file.
4026 The built-in command . file reads the whole file before any commands
4028 are executed. Therefore, alias and unalias commands in the file will
4029 not apply to any commands defined in the file.
4030 Traps are not processed while a job is waiting for a foreground
4032 process. Thus, a trap on CHLD won't be executed until the foreground
4033 job terminates.
4034 In locales that use a multibyte character set such as UTF-8, the KEYBD
4036 trap is only triggered for ASCII characters (1-127).
4037 It is a good idea to leave a space after the comma operator in arith‐
4039 metic expressions to prevent the comma from being interpreted as the
4040 decimal point character in certain locales.
4041 KSH(1)