1 .\" $MirOS: src/bin/mksh/mksh.1,v 1.377 2015/07/10 19:35:39 tg Exp $
2 .\" $OpenBSD: ksh.1,v 1.160 2015/07/04 13:27:04 feinerer Exp $
4 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
5 .\" 2010, 2011, 2012, 2013, 2014, 2015
6 .\" Thorsten “mirabilos” Glaser <tg@mirbsd.org>
8 .\" Provided that these terms and disclaimer and all copyright notices
9 .\" are retained or reproduced in an accompanying document, permission
10 .\" is granted to deal in this work without restriction, including un‐
11 .\" limited rights to use, publicly perform, distribute, sell, modify,
12 .\" merge, give away, or sublicence.
14 .\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
15 .\" the utmost extent permitted by applicable law, neither express nor
16 .\" implied; without malicious intent or gross negligence. In no event
17 .\" may a licensor, author or contributor be held liable for indirect,
18 .\" direct, other damage, loss, or other issues arising in any way out
19 .\" of dealing in the work, even if advised of the possibility of such
20 .\" damage or existence of a defect, except proven that it results out
21 .\" of said person’s immediate fault when using the work as intended.
23 .\" Try to make GNU groff and AT&T nroff more compatible
24 .\" * ` generates ‘ in gnroff, so use \`
25 .\" * ' generates ’ in gnroff, \' generates ´, so use \*(aq
26 .\" * - generates ‐ in gnroff, \- generates −, so .tr it to -
27 .\" thus use - for hyphens and \- for minus signs and option dashes
28 .\" * ~ is size-reduced and placed atop in groff, so use \*(TI
29 .\" * ^ is size-reduced and placed atop in groff, so use \*(ha
30 .\" * \(en does not work in nroff, so use \*(en
31 .\" * <>| are problematic, so redefine and use \*(Lt\*(Gt\*(Ba
32 .\" Also make sure to use \& especially with two-letter words.
33 .\" The section after the "doc" macropackage has been loaded contains
34 .\" additional code to convene between the UCB mdoc macropackage (and
35 .\" its variant as BSD mdoc in groff) and the GNU mdoc macropackage.
38 . if
\ 1\*[.T]
\ 1ascii
\ 1 .tr \-\N'45'
39 . if
\ 1\*[.T]
\ 1latin1
\ 1 .tr \-\N'45'
40 . if
\ 1\*[.T]
\ 1utf8
\ 1 .tr \-\N'45'
47 . if
\ 1\*[.T]
\ 1utf8
\ 1 .ds sL `
48 . if
\ 1\*[.T]
\ 1ps
\ 1 .ds sL `
49 . if
\ 1\*[.T]
\ 1utf8
\ 1 .ds sR '
50 . if
\ 1\*[.T]
\ 1ps
\ 1 .ds sR '
63 .\" Implement .Dd with the Mdocdate RCS keyword
67 .ie
\a\\$1
\a$Mdocdate:
\a \{\
70 .el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8
73 .\" .Dd must come before definition of .Mx, because when called
74 .\" with -mandoc, it might implement .Mx itself, but we want to
75 .\" use our own definition. And .Dd must come *first*, always.
77 .Dd $Mdocdate: July 10 2015 $
79 .\" Check which macro package we use, and do other -mdoc setup.
82 . if
\ 1\*[.T]
\ 1utf8
\ 1 .tr \[la]\*(Lt
83 . if
\ 1\*[.T]
\ 1utf8
\ 1 .tr \[ra]\*(Gt
84 . ie d volume-ds-1 .ds tT gnu
89 .\" Implement .Mx (MirBSD)
95 . nr curr-size \n[.ps]
96 . ds str-Mx \f[\n[curr-font]]\s[\n[curr-size]u]
97 . ds str-Mx1 \*[Tn-font-size]\%MirOS\*[str-Mx]
103 . if (\n[arg-limit] > \n[arg-ptr]) \{\
105 . ie (\n[type\n[arg-ptr]] == 2) \
106 . as str-Mx1 \~\*[arg\n[arg-ptr]]
110 . ds arg\n[arg-ptr] "\*[str-Mx1]
111 . nr type\n[arg-ptr] 2
112 . ds space\n[arg-ptr] "\*[space]
113 . nr num-args (\n[arg-limit] - \n[arg-ptr])
114 . nr arg-limit \n[arg-ptr]
121 . ds tN \*[Tn-font-size]
127 . ds aa \&\f\\n(cF\s\\n(cZ
129 . ie \\n(.$==0 \&MirOS\\*(aa
130 . el .aV \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
132 . if \\n(aC>\\n(aP \{\
134 . ie \\n(C\\n(aP==2 \{\
135 . as b1 \&MirOS\ #\&\\*(A\\n(aP\\*(aa
136 . ie \\n(aC>\\n(aP \{\
143 . as b1 \&MirOS\\*(aa
155 .Nd MirBSD Korn shell
159 .Op Fl +abCefhiklmnprUuvXx
161 .Fl T Oo Ar \&! Oc Ns Ar tty
167 .Fl c Ar string \*(Ba
177 is a command interpreter intended for both interactive and shell
179 Its command language is a superset of the
181 shell language and largely compatible to the original Korn shell.
182 .Ss I'm an Android user, so what's mksh?
186 shell / command interpreter, similar to
190 which has been included with
191 .Tn Android Open Source Project
193 Basically, it's a program that runs in a terminal (console window),
194 takes user input and runs commands or scripts, which it can also
195 be asked to do by other programs, even in the background.
196 Any privilege pop-ups you might be encountering are thus not
198 issues but questions by some other program utilising it.
200 Most builtins can be called directly, for example if a link points from its
201 name to the shell; not all make sense, have been tested or work at all though.
203 The options are as follows:
204 .Bl -tag -width XcXstring
207 will execute the command(s) contained in
211 A shell that reads commands from standard input is
214 option is used or if both standard input and standard error are attached
217 An interactive shell has job control enabled, ignores the
222 signals, and prints prompts before reading input (see the
227 It also processes the
232 For non-interactive shells, the
234 option is on by default (see the
239 If the basename the shell is called with (i.e. argv[0])
242 or if this option is used,
243 the shell is assumed to be a login shell; see
250 if the real user ID or group ID does not match the
251 effective user ID or group ID (see
255 Clearing the privileged option causes the shell to set
256 its effective user ID (group ID) to its real user ID (group ID).
257 For further implications, see
259 If the shell is privileged and this flag is not explicitly set, the
261 option is cleared automatically after processing the startup files.
268 The following restrictions come into effect after the shell processes any
285 parameters cannot be changed.
287 Command names can't be specified with absolute or relative paths.
291 option of the built-in command
295 Redirections that create files can't be used (i.e.\&
302 The shell reads commands from standard input; all non-option arguments
303 are positional parameters.
312 .Pa /dev/ttyC Ns Ar name
314 .Pa /dev/tty Ns Ar name
315 are attempted in order.
318 begins with an exclamation mark
320 this is done in a subshell and returns immediately.
325 detach from controlling terminal (daemonise) instead.
328 In addition to the above, the options described in the
330 built-in command can also be used on the command line:
332 .Op Fl +abCefhkmnuvXx
335 can be used for single letter or long options, respectively.
341 option is specified, the first non-option argument specifies the name
342 of a file the shell reads commands from.
343 If there are no non-option
344 arguments, the shell reads commands from the standard input.
345 The name of the shell (i.e. the contents of $0)
346 is determined as follows: if the
348 option is used and there is a non-option argument, it is used as the name;
349 if commands are being read from a file, the file is used as the name;
350 otherwise, the basename the shell was called with (i.e. argv[0]) is used.
352 The exit status of the shell is 127 if the command file specified on the
353 command line could not be opened, or non-zero if a fatal syntax error
354 occurred during the execution of a script.
355 In the absence of fatal errors,
356 the exit status is that of the last command executed, or zero, if no
359 For the actual location of these files, see
361 A login shell processes the system profile first.
362 A privileged shell then processes the suid profile.
363 A non-privileged login shell processes the user profile next.
364 A non-privileged interactive shell checks the value of the
366 parameter after subjecting it to parameter, command, arithmetic and tilde
368 substitution; if unset or empty, the user mkshrc profile is processed;
369 otherwise, if a file whose name is the substitution result exists,
370 it is processed; non-existence is silently ignored.
371 A privileged shell then drops privileges if neither was the
373 option given on the command line nor set during execution of the startup files.
375 The shell begins parsing its input by removing any backslash-newline
376 combinations, then breaking it into
378 Words (which are sequences of characters) are delimited by unquoted whitespace
379 characters (space, tab, and newline) or meta-characters
390 Aside from delimiting words, spaces and tabs are ignored, while newlines
391 usually delimit commands.
392 The meta-characters are used in building the following
397 .Ql \*(Lt\*(Lt\*(Lt ,
402 etc. are used to specify redirections (see
403 .Sx Input/output redirection
406 is used to create pipelines;
408 is used to create co-processes (see
412 is used to separate commands;
414 is used to create asynchronous pipelines;
418 are used to specify conditional execution;
427 is used in arithmetic expressions;
430 is used to create subshells.
432 Whitespace and meta-characters can be quoted individually using a backslash
434 or in groups using double
439 Note that the following characters are also treated specially by the
440 shell and must be quoted if they are to represent themselves:
454 The first three of these are the above mentioned quoting characters (see
458 if used at the beginning of a word, introduces a comment \*(en everything after
461 up to the nearest newline is ignored;
463 is used to introduce parameter, command, and arithmetic substitutions (see
467 introduces an old-style command substitution (see
471 begins a directory expansion (see
487 are used in file name generation (see
488 .Sx File name patterns
491 As words and tokens are parsed, the shell builds commands, of which there
493 .Em simple-commands ,
494 typically programmes that are executed, and
495 .Em compound-commands ,
500 statements, grouping constructs, and function definitions.
502 A simple-command consists of some combination of parameter assignments
506 input/output redirections (see
507 .Sx Input/output redirections
509 and command words; the only restriction is that parameter assignments come
510 before any command words.
511 The command words, if any, define the command
512 that is to be executed and its arguments.
513 The command may be a shell built-in command, a function,
514 or an external command
515 (i.e. a separate executable file that is located using the
518 .Sx Command execution
520 Note that all command constructs have an exit status: for external commands,
521 this is related to the status returned by
523 (if the command could not be found, the exit status is 127; if it could not
524 be executed, the exit status is 126); the exit status of other command
525 constructs (built-in commands, functions, compound-commands, pipelines, lists,
526 etc.) are all well-defined and are described where the construct is
528 The exit status of a command consisting only of parameter
529 assignments is that of the last command substitution performed during the
530 parameter assignment or 0 if there were no command substitutions.
532 Commands can be chained together using the
534 token to form pipelines, in which the standard output of each command but the
537 to the standard input of the following command.
538 The exit status of a pipeline is that of its last command, unless the
540 option is set (see there).
541 All commands of a pipeline are executed in separate subshells;
542 this is allowed by POSIX but differs from both variants of
545 where all but the last command were executed in subshells; see the
547 builtin's description for implications and workarounds.
548 A pipeline may be prefixed by the
550 reserved word which causes the exit status of the pipeline to be logically
551 complemented: if the original status was 0, the complemented status will be 1;
552 if the original status was not 0, the complemented status will be 0.
555 of commands can be created by separating pipelines by any of the following
563 The first two are for conditional execution:
564 .Dq Ar cmd1 No && Ar cmd2
567 only if the exit status of
571 is the opposite \*(en
573 is executed only if the exit status of
579 have equal precedence which is higher than that of
584 which also have equal precedence.
590 .Qq left-associative .
591 For example, both of these commands will print only
593 .Bd -literal -offset indent
594 $ false && echo foo \*(Ba\*(Ba echo bar
595 $ true \*(Ba\*(Ba echo foo && echo bar
600 token causes the preceding command to be executed asynchronously; that is,
601 the shell starts the command but does not wait for it to complete (the shell
602 does keep track of the status of asynchronous commands; see
605 When an asynchronous command is started when job control is disabled
606 (i.e. in most scripts), the command is started with signals
610 ignored and with input redirected from
612 (however, redirections specified in the asynchronous command have precedence).
615 operator starts a co-process which is a special kind of asynchronous process
619 Note that a command must follow the
623 operators, while it need not follow
628 The exit status of a list is that of the last command executed, with the
629 exception of asynchronous lists, for which the exit status is 0.
631 Compound commands are created using the following reserved words.
633 are only recognised if they are unquoted and if they are used as the first
634 word of a command (i.e. they can't be preceded by parameter assignments or
636 .Bd -literal -offset indent
637 case else function then ! (
638 do esac if time [[ ((
640 elif for select while }
643 In the following compound command descriptions, command lists (denoted as
645 that are followed by reserved words must end with a semicolon, a newline, or
646 a (syntactically correct) reserved word.
647 For example, the following are all valid:
648 .Bd -literal -offset indent
649 $ { echo foo; echo bar; }
650 $ { echo foo; echo bar\*(Ltnewline\*(Gt}
651 $ { { echo foo; echo bar; } }
656 .Dl $ { echo foo; echo bar }
662 There is no implicit way to pass environment changes from a
663 subshell back to its parent.
667 is executed, but not in a subshell.
672 are reserved words, not meta-characters.
673 .It Xo case Ar word No in
684 statement attempts to match
690 associated with the first successfully matched pattern is executed.
693 statements are the same as those used for file name patterns except that the
694 restrictions regarding
699 Note that any unquoted space before and after a pattern is
700 stripped; any space within a pattern must be quoted.
701 Both the word and the
702 patterns are subject to parameter, command, and arithmetic substitution, as
703 well as tilde substitution.
705 For historical reasons, open and close braces may be used instead of
710 .Ic case $foo { *) echo bar ;; } .
717 Terminate after the list.
719 Fall through into the next list.
721 Evaluate the remaining pattern-list tuples.
726 statement is that of the executed
730 is executed, the exit status is zero.
732 .Oo in Ar word No ... Oc ;
733 .No do Ar list ; No done
737 in the specified word list, the parameter
739 is set to the word and
744 is not used to specify a word list, the positional parameters
747 For historical reasons, open and close braces may be used instead of
752 .Ic for i; { echo $i; } .
755 statement is the last exit status of
759 is never executed, the exit status is zero.
763 .No then Ar list ; Oc
765 .Oo else Ar list ; Oc
768 If the exit status of the first
772 is executed; otherwise, the
776 if any, is executed with similar consequences.
777 If all the lists following the
781 fail (i.e. exit with non-zero status), the
786 The exit status of an
788 statement is that of non-conditional
790 that is executed; if no non-conditional
792 is executed, the exit status is zero.
793 .It Xo select Ar name
794 .Oo in Ar word No ... Oc ;
795 .No do Ar list ; No done
799 statement provides an automatic method of presenting the user with a menu and
801 An enumerated list of the specified
803 is printed on standard error, followed by a prompt
808 A number corresponding to one of the enumerated words is then read from
811 is set to the selected word (or unset if the selection is not valid),
813 is set to what was read (leading/trailing space is stripped), and
816 If a blank line (i.e. zero or more
818 octets) is entered, the menu is reprinted without executing
823 completes, the enumerated list is printed if
827 the prompt is printed, and so on.
828 This process continues until an end-of-file
829 is read, an interrupt is received, or a
831 statement is executed inside the loop.
834 is omitted, the positional parameters are used
836 For historical reasons, open and close braces may be used instead of
841 .Ic select i; { echo $i; } .
844 statement is zero if a
846 statement is used to exit the loop, non-zero otherwise.
847 .It Xo until Ar list ;
853 except that the body is executed only while the exit status of the first
856 .It Xo while Ar list ;
862 is a pre-checked loop.
863 Its body is executed as often as the exit status of the first
868 statement is the last exit status of the
870 in the body of the loop; if the body is not executed, the exit status is zero.
871 .It Xo function Ar name
879 Note that redirections specified after a function definition are
880 performed whenever the function is executed, not when the function definition
882 .It Ar name Ns \&() Ar command
888 Whitespace (space or tab) after
890 will be ignored most of the time.
891 .It Xo function Ar name Ns \&()
900 .It Xo Ic time Op Fl p
904 .Sx Command execution
905 section describes the
908 .It \&(( Ar expression No ))
909 The arithmetic expression
911 is evaluated; equivalent to
914 .Sx Arithmetic expressions
918 .It Bq Bq Ar \ \&expression\ \&
923 commands (described later), with the following exceptions:
926 Field splitting and file name generation are not performed on arguments.
934 operators are replaced with
946 Parameter, command, and arithmetic substitutions are performed as expressions
947 are evaluated and lazy expression evaluation is used for the
952 This means that in the following statement,
954 is evaluated if and only if the file
956 exists and is readable:
957 .Bd -literal -offset indent
958 $ [[ \-r foo && $(\*(Ltfoo) = b*r ]]
961 The second operand of the
965 expressions are a subset of patterns (e.g. the comparison
966 .Ic \&[[ foobar = f*r ]]
968 This even works indirectly:
969 .Bd -literal -offset indent
970 $ bar=foobar; baz=\*(aqf*r\*(aq
971 $ [[ $bar = $baz ]]; echo $?
972 $ [[ $bar = \&"$baz" ]]; echo $?
975 Perhaps surprisingly, the first comparison succeeds,
976 whereas the second doesn't.
977 This does not apply to all extglob metacharacters, currently.
981 Quoting is used to prevent the shell from treating characters or words
983 There are three methods of quoting.
986 quotes the following character, unless it is at the end of a line, in which
989 and the newline are stripped.
990 Second, a single quote
992 quotes everything up to the next single quote (this may span lines).
993 Third, a double quote
995 quotes all characters, except
1000 up to the next unquoted double quote.
1004 inside double quotes have their usual meaning (i.e. parameter, command, or
1005 arithmetic substitution) except no field splitting is carried out on the
1006 results of double-quoted substitutions.
1009 inside a double-quoted string is followed by
1015 it is replaced by the second character; if it is followed by a newline, both
1018 and the newline are stripped; otherwise, both the
1020 and the character following are unchanged.
1022 If a single-quoted string is preceded by an unquoted
1024 C style backslash expansion (see below) is applied (even single quote
1025 characters inside can be escaped and do not terminate the string then);
1026 the expanded result is treated as any other single-quoted string.
1027 If a double-quoted string is preceded by an unquoted
1029 the latter is ignored.
1030 .Ss Backslash expansion
1031 In places where backslashes are expanded, certain C and
1036 style escapes are translated.
1053 means a hexadecimal digit, of thich there may be none up to four or eight;
1054 these escapes translate a Unicode codepoint to UTF-8.
1059 expand to the escape character.
1068 are explicitly excluded;
1069 octal sequences must have the none up to three octal digits
1071 prefixed with the digit zero
1073 hexadecimal sequences
1075 are limited to none up to two hexadecimal digits
1077 both octal and hexadecimal sequences convert to raw octets;
1079 where # is none of the above, translates to \e# (backslashes are retained).
1081 Backslash expansion in the C style mode slightly differs: octal sequences
1083 must have no digit zero prefixing the one up to three octal digits
1085 and yield raw octets; hexadecimal sequences
1087 greedily eat up as many hexadecimal digits
1089 as they can and terminate with the first non-hexadecimal digit;
1090 these translate a Unicode codepoint to UTF-8.
1095 is any octet, translates to Ctrl-# (which basically means,
1097 becomes DEL, everything else is bitwise ANDed with 0x1F).
1100 where # is none of the above, translates to # (has the backslash trimmed),
1101 even if it is a newline.
1103 There are two types of aliases: normal command aliases and tracked aliases.
1104 Command aliases are normally used as a short hand for a long or often used
1106 The shell expands command aliases (i.e. substitutes the alias name
1107 for its value) when it reads the first word of a command.
1108 An expanded alias is re-processed to check for more aliases.
1109 If a command alias ends in a
1110 space or tab, the following word is also checked for alias expansion.
1111 The alias expansion process stops when a word that is not an alias is found,
1112 when a quoted word is found, or when an alias word that is currently being
1114 Aliases are specifically an interactive feature: while they do happen
1115 to work in scripts and on the command line in some cases, aliases are
1116 expanded during lexing, so their use must be in a separate command tree
1117 from their definition; otherwise, the alias will not be found.
1118 Noticeably, command lists (separated by semicolon, in command substitutions
1119 also by newline) may be one same parse tree.
1121 The following command aliases are defined automatically by the shell:
1122 .Bd -literal -offset indent
1123 autoload=\*(aq\etypeset \-fu\*(aq
1124 functions=\*(aq\etypeset \-f\*(aq
1125 hash=\*(aq\ebuiltin alias \-t\*(aq
1126 history=\*(aq\ebuiltin fc \-l\*(aq
1127 integer=\*(aq\etypeset \-i\*(aq
1128 local=\*(aq\etypeset\*(aq
1129 login=\*(aq\eexec login\*(aq
1130 nameref=\*(aq\etypeset \-n\*(aq
1131 nohup=\*(aqnohup \*(aq
1132 r=\*(aq\ebuiltin fc \-e \-\*(aq
1133 source=\*(aqPATH=$PATH:. \ecommand .\*(aq
1134 stop=\*(aq\ekill \-STOP\*(aq
1135 type=\*(aq\ebuiltin whence \-v\*(aq
1138 Tracked aliases allow the shell to remember where it found a particular
1140 The first time the shell does a path search for a command that is
1141 marked as a tracked alias, it saves the full path of the command.
1143 time the command is executed, the shell checks the saved path to see that it
1144 is still valid, and if so, avoids repeating the path search.
1145 Tracked aliases can be listed and created using
1147 Note that changing the
1149 parameter clears the saved paths for all tracked aliases.
1152 option is set (i.e.\&
1153 .Ic set Fl o Ic trackall
1156 the shell tracks all commands.
1157 This option is set automatically for non-interactive shells.
1158 For interactive shells, only the following commands are
1159 automatically tracked:
1179 The first step the shell takes in executing a simple-command is to perform
1180 substitutions on the words of the command.
1181 There are three kinds of
1182 substitution: parameter, command, and arithmetic.
1183 Parameter substitutions,
1184 which are described in detail in the next section, take the form
1187 .Pf ${ Ns Ar ... Ns } ;
1188 command substitutions take the form
1189 .Pf $( Ns Ar command Ns \&)
1191 .Pf \` Ns Ar command Ns \`
1192 or (executed in the current environment)
1193 .Pf ${\ \& Ar command Ns \&;}
1194 and strip trailing newlines;
1195 and arithmetic substitutions take the form
1196 .Pf $(( Ns Ar expression Ns )) .
1197 Parsing the current-environment command substitution requires a space,
1198 tab or newline after the opening brace and that the closing brace be
1199 recognised as a keyword (i.e. is preceded by a newline or semicolon).
1200 They are also called funsubs (function substitutions) and behave like
1207 terminates the parent shell; shell options are shared.
1209 Another variant of substitution are the valsubs (value substitutions)
1210 .Pf ${\*(Ba\& Ns Ar command Ns \&;}
1211 which are also executed in the current environment, like funsubs, but
1212 share their I/O with the parent; instead, they evaluate to whatever
1213 the, initially empty, expression-local variable
1215 is set to within the
1218 If a substitution appears outside of double quotes, the results of the
1219 substitution are generally subject to word or field splitting according to
1220 the current value of the
1225 parameter specifies a list of octets which are used to break a string up
1226 into several words; any octets from the set space, tab, and newline that
1230 .Dq IFS whitespace .
1231 Sequences of one or more
1233 whitespace octets, in combination with zero or one
1235 whitespace octets, delimit a field.
1236 As a special case, leading and trailing
1238 whitespace is stripped (i.e. no leading or trailing empty field
1239 is created by it); leading or trailing
1241 whitespace does create an empty field.
1246 .Dq \*(Ltspace\*(Gt: ,
1248 .Dq \*(Ltspace\*(GtA\*(Ltspace\*(Gt:\*(Ltspace\*(Gt\*(Ltspace\*(GtB::D ,
1249 the substitution for $VAR results in four fields:
1258 parameter is set to the empty string, no field splitting is done;
1259 if it is unset, the default value of space, tab, and newline is used.
1261 Also, note that the field splitting applies only to the immediate result of
1263 Using the previous example, the substitution for $VAR:E
1264 results in the fields:
1277 This behavior is POSIX compliant, but incompatible with some other shell
1278 implementations which do field splitting on the word which contained the
1281 as a general whitespace delimiter.
1283 The results of substitution are, unless otherwise specified, also subject to
1284 brace expansion and file name expansion (see the relevant sections below).
1286 A command substitution is replaced by the output generated by the specified
1287 command which is run in a subshell.
1289 .Pf $( Ns Ar command Ns \&)
1291 .Pf ${\ \& Ar command Ns \&;}
1292 substitutions, normal quoting rules are used when
1294 is parsed; however, for the deprecated
1295 .Pf \` Ns Ar command Ns \`
1305 followed by any other character is unchanged).
1306 As a special case in command substitutions, a command of the form
1308 is interpreted to mean substitute the contents of
1312 has the same effect as
1315 Note that some shells do not use a recursive parser for command substitutions,
1316 leading to failure for certain constructs; to be portable, use as workaround
1317 .Ql x=$(cat) \*(Lt\*(Lt"EOF"
1318 (or the newline-keeping
1319 .Ql x=\*(Lt\*(Lt"EOF"
1320 extension) instead to merely slurp the string.
1322 recommends to use case statements of the form
1323 .Ql "x=$(case $foo in (bar) echo $bar ;; (*) echo $baz ;; esac)"
1324 instead, which would work but not serve as example for this portability issue.
1325 .Bd -literal -offset indent
1326 x=$(case $foo in bar) echo $bar ;; *) echo $baz ;; esac)
1327 # above fails to parse on old shells; below is the workaround
1328 x=$(eval $(cat)) \*(Lt\*(Lt"EOF"
1329 case $foo in bar) echo $bar ;; *) echo $baz ;; esac
1333 Arithmetic substitutions are replaced by the value of the specified expression.
1334 For example, the command
1335 .Ic print $((2+3*4))
1338 .Sx Arithmetic expressions
1339 for a description of an expression.
1341 Parameters are shell variables; they can be assigned values and their values
1342 can be accessed using a parameter substitution.
1343 A parameter name is either one
1344 of the special single punctuation or digit character parameters described
1345 below, or a letter followed by zero or more letters or digits
1350 The latter form can be treated as arrays by appending an array index of the
1355 is an arithmetic expression.
1358 are limited to the range 0 through 4294967295, inclusive.
1359 That is, they are a 32-bit unsigned integer.
1361 Parameter substitutions take the form
1363 .Pf ${ Ns Ar name Ns } ,
1366 .Pf ${ Ar name Oo Ar expr Oc }
1370 is a parameter name.
1371 Substitution of all array elements with
1372 .Pf ${ Ns Ar name Ns \&[*]}
1374 .Pf ${ Ns Ar name Ns \&[@]}
1375 works equivalent to $* and $@ for positional parameters.
1376 If substitution is performed on a parameter
1377 (or an array parameter element)
1378 that is not set, a null string is substituted unless the
1382 .Ic set Fl o Ic nounset
1386 is set, in which case an error occurs.
1388 Parameters can be assigned values in a number of ways.
1389 First, the shell implicitly sets some parameters like
1394 this is the only way the special single character parameters are set.
1395 Second, parameters are imported from the shell's environment at startup.
1396 Third, parameters can be assigned values on the command line: for example,
1402 multiple parameter assignments can be given on a single command line and they
1403 can be followed by a simple-command, in which case the assignments are in
1404 effect only for the duration of the command (such assignments are also
1405 exported; see below for the implications of this).
1406 Note that both the parameter name and the
1408 must be unquoted for the shell to recognise a parameter assignment.
1411 is also recognised; the old and new values are immediately concatenated.
1412 The fourth way of setting a parameter is with the
1418 commands; see their descriptions in the
1419 .Sx Command execution
1425 loops set parameters as well as the
1431 Lastly, parameters can be assigned values using assignment operators
1432 inside arithmetic expressions (see
1433 .Sx Arithmetic expressions
1436 .Pf ${ Ar name No = Ar value No }
1438 form of the parameter substitution (see below).
1440 Parameters with the export attribute (set using the
1444 commands, or by parameter assignments followed by simple commands) are put in
1445 the environment (see
1447 of commands run by the shell as
1448 .Ar name Ns = Ns Ar value
1450 The order in which parameters appear in the environment of a command is
1452 When the shell starts up, it extracts parameters and their values
1453 from its environment and automatically sets the export attribute for those
1456 Modifiers can be applied to the
1457 .Pf ${ Ns Ar name Ns }
1458 form of parameter substitution:
1461 .It ${ Ar name No :\- Ar word No }
1467 it is substituted; otherwise,
1471 .It ${ Ar name No :+ Ar word No }
1478 is substituted; otherwise, nothing is substituted.
1480 .It ${ Ar name No := Ar word No }
1486 it is substituted; otherwise, it is assigned
1488 and the resulting value of
1492 .It ${ Ar name No :? Ar word No }
1498 it is substituted; otherwise,
1500 is printed on standard error (preceded by
1502 and an error occurs (normally causing termination of a shell script, function,
1503 or script sourced using the
1508 is omitted, the string
1509 .Dq parameter null or not set
1513 is a variable which expands to the null string, the
1514 error message is also printed.
1517 Note that, for all of the above,
1519 is actually considered quoted, and special parsing rules apply.
1520 The parsing rules also differ on whether the expression is double-quoted:
1522 then uses double-quoting rules, except for the double quote itself
1524 and the closing brace, which, if backslash escaped, gets quote removal applied.
1526 In the above modifiers, the
1528 can be omitted, in which case the conditions only depend on
1530 being set (as opposed to set and not
1534 is needed, parameter, command, arithmetic, and tilde substitution are performed
1537 is not needed, it is not evaluated.
1539 The following forms of parameter substitution can also be used (if
1541 is an array, the element with the key
1543 will be substituted in scalar context):
1545 .Bl -tag -width Ds -compact
1546 .It Pf ${# Ns Ar name Ns \&}
1547 The number of positional parameters if
1552 or not specified; otherwise the length
1554 of the string value of parameter
1557 .It Pf ${# Ns Ar name Ns \&[*]}
1558 .It Pf ${# Ns Ar name Ns \&[@]}
1559 The number of elements in the array
1562 .It Pf ${% Ns Ar name Ns \&}
1564 .Pq in screen columns
1565 of the string value of parameter
1568 .Pf ${ Ns Ar name Ns }
1569 contains a control character.
1571 .It Pf ${! Ns Ar name Ns }
1572 The name of the variable referred to by
1578 is a name reference (bound variable), created by the
1580 command (which is an alias for
1581 .Ic typeset Fl n ) .
1583 .It Pf ${! Ns Ar name Ns \&[*]}
1584 .It Pf ${! Ns Ar name Ns \&[@]}
1585 The names of indices (keys) in the array
1591 .Pf # Ar pattern No }
1595 .Pf ## Ar pattern No }
1600 matches the beginning of the value of parameter
1602 the matched text is deleted from the result of substitution.
1605 results in the shortest match, and two
1606 of them result in the longest match.
1607 Cannot be applied to a vector
1608 .Pq ${*} or ${@} or ${array[*]} or ${array[@]} .
1613 .Pf % Ar pattern No }
1617 .Pf %% Ar pattern No }
1620 Like ${..#..} substitution, but it deletes from the end of the value.
1621 Cannot be applied to a vector.
1626 .Pf / Ar pattern / Ar string No }
1630 .Pf // Ar pattern / Ar string No }
1633 Similar to ${..##..} substitution, but it replaces the longest match of
1635 anchored anywhere in the value, with
1641 it is anchored at the beginning of the value; if it begins with
1643 it is anchored at the end.
1644 Empty patterns cause no replacement to happen.
1647 or use of a pattern that matches the empty string causes the
1648 replacement to happen only once; two leading slashes cause
1649 all occurrences of matches in the value to be replaced.
1652 is omitted, any matches of
1654 are replaced by the empty string, i.e. deleted.
1655 Cannot be applied to a vector.
1656 Inefficiently implemented, may be slow.
1660 .Pf ${ Ar name : Ns Ar pos
1661 .Pf : Ns Ar len Ns }
1668 starting at position
1678 is negative, counting starts at the end of the string; if it
1679 is omitted, it defaults to 0.
1682 is omitted or greater than the length of the remaining string,
1683 all of it is substituted.
1688 are evaluated as arithmetic expressions.
1691 must start with a space, opening parenthesis or digit to be recognised.
1692 Cannot be applied to a vector.
1694 .It Pf ${ Ns Ar name Ns @#}
1695 The hash (using the BAFH algorithm) of the expansion of
1697 This is also used internally for the shell's hashtables.
1699 .It Pf ${ Ns Ar name Ns @Q}
1700 A quoted expression safe for re-entry, whose value is the value of the
1702 parameter, is substituted.
1707 may need extended globbing pattern
1710 .Pq \&\*(aq...\&\*(aq
1713 quote escaping unless
1717 The following special parameters are implicitly set by the shell and cannot be
1718 set directly using assignments:
1719 .Bl -tag -width "1 .. 9"
1721 Process ID of the last background process started.
1722 If no background processes have been started, the parameter is not set.
1724 The number of positional parameters ($1, $2, etc.).
1726 The PID of the shell, or the PID of the original shell if it is a subshell.
1729 use this mechanism for generating temporary file names; see
1733 The concatenation of the current single letter options (see the
1735 command below for a list of options).
1737 The exit status of the last non-asynchronous command executed.
1738 If the last command was killed by a signal,
1740 is set to 128 plus the signal number.
1742 The name of the shell, determined as follows:
1743 the first argument to
1745 if it was invoked with the
1747 option and arguments were given; otherwise the
1749 argument, if it was supplied;
1750 or else the basename the shell was invoked with (i.e.\&
1753 is also set to the name of the current script or
1754 the name of the current function, if it was defined with the
1756 keyword (i.e. a Korn shell style function).
1758 The first nine positional parameters that were supplied to the shell, function,
1759 or script sourced using the
1762 Further positional parameters may be accessed using
1763 .Pf ${ Ar number Ns } .
1765 All positional parameters (except 0), i.e. $1, $2, $3, ...
1768 outside of double quotes, parameters are separate words (which are subjected
1769 to word splitting); if used within double quotes, parameters are separated
1770 by the first character of the
1772 parameter (or the empty string if
1779 unless it is used inside double quotes, in which case a separate word is
1780 generated for each positional parameter.
1781 If there are no positional parameters, no word is generated.
1783 can be used to access arguments, verbatim, without losing
1785 arguments or splitting arguments with spaces.
1788 The following parameters are set and/or used by the shell:
1789 .Bl -tag -width "KSH_VERSION"
1792 When an external command is executed by the shell, this parameter is set in the
1793 environment of the new process to the path of the executed command.
1794 In interactive use, this parameter is also set in the parent shell to the last
1795 word of the previous command.
1797 The PID of the shell or subshell.
1801 but used to resolve the argument to the
1806 is set and does not contain
1808 or an empty string element, the current directory is not searched.
1811 built-in command will display the resulting directory when a match is found
1812 in any search path other than the empty path.
1814 Set to the number of columns on the terminal or window.
1815 Always set, defaults to 80, unless the
1816 value as reported by
1818 is non-zero and sane enough (minimum is 12x3); similar for
1820 This parameter is used by the interactive line editing modes, and by the
1825 commands to format information columns.
1826 Importing from the environment or unsetting this parameter removes the
1827 binding to the actual terminal size in favour of the provided value.
1829 If this parameter is found to be set after any profile files are executed, the
1830 expanded value is used as a shell startup file.
1831 It typically contains function and alias definitions.
1833 Integer value of the shell's
1836 It indicates the reason the last system call failed.
1837 Not yet implemented.
1839 If set, this parameter is assumed to contain the shell that is to be used to
1840 execute commands that
1842 fails to execute and which do not start with a
1846 The editor used by the
1848 command (see below).
1852 but used when an undefined function is executed to locate the file defining the
1854 It is also searched when a command can't be found using
1858 below for more information.
1860 The name of the file used to store command history.
1861 When assigned to or unset, the file is opened, history is truncated
1862 then loaded from the file; subsequent new commands (possibly consisting
1863 of several lines) are appended once they successfully compiled.
1864 Also, several invocations of the shell will share history if their
1866 parameters all point to the same file.
1871 is unset or empty, no history file is used.
1872 This is different from
1876 The number of commands normally stored for history.
1877 The default is 2047.
1878 Do not set this value to insanely high values such as 1000000000 because
1880 can then not allocate enough memory for the history and will not start.
1882 The default directory for the
1884 command and the value substituted for an unqualified
1890 Internal field separator, used during substitution and by the
1892 command, to split values into distinct arguments; normally set to space, tab,
1899 This parameter is not imported from the environment when the shell is
1902 The effective group id of the shell.
1904 The real group id of the shell.
1906 The real user id of the shell.
1908 The name and version of the shell (read-only).
1909 See also the version commands in
1910 .Sx Emacs editing mode
1915 The line number of the function or shell script that is currently being
1918 Set to the number of lines on the terminal or window.
1919 Always set, defaults to 24.
1922 .It Ev EPOCHREALTIME
1923 Time since the epoch, as returned by
1924 .Xr gettimeofday 2 ,
1925 formatted as decimal
1931 padded to exactly six decimal digits.
1933 The previous working directory.
1936 has not successfully changed directories since the shell started, or if the
1937 shell doesn't know where it is.
1941 it contains the argument for a parsed option, if it requires one.
1943 The index of the next argument to be processed when using
1945 Assigning 1 to this parameter causes
1947 to process arguments from the beginning the next time it is invoked.
1949 A colon separated list of directories that are searched when looking for
1950 commands and files sourced using the
1952 command (see below).
1953 An empty string resulting from a leading or trailing
1954 colon, or two adjacent colons, is treated as a
1956 (the current directory).
1958 The process ID of the shell's process group leader.
1960 An array containing the errorlevel (exit status) codes,
1961 one by one, of the last pipeline run in the foreground.
1963 The process ID of the shell's parent.
1965 The primary prompt for interactive shells.
1966 Parameter, command, and arithmetic
1967 substitutions are performed, and
1969 is replaced with the current command number (see the
1974 can be put in the prompt by placing
1979 The default prompt is
1986 is invoked by root and
1990 character, the default value will be used even if
1992 already exists in the environment.
1996 distribution comes with a sample
1998 containing a sophisticated example, but you might like the following one
1999 (note that ${HOSTNAME:=$(hostname)} and the
2000 root-vs-user distinguishing clause are (in this example) executed at
2002 assignment time, while the $USER and $PWD are escaped
2003 and thus will be evaluated each time a prompt is displayed):
2005 PS1=\*(aq${USER:=$(id \-un)}\*(aq"@${HOSTNAME:=$(hostname)}:\e$PWD $(
2006 if (( USER_ID )); then print \e$; else print \e#; fi) "
2009 Note that since the command-line editors try to figure out how long the prompt
2010 is (so they know how far it is to the edge of the screen), escape codes in
2011 the prompt tend to mess things up.
2012 You can tell the shell not to count certain
2013 sequences (such as escape codes) by prefixing your prompt with a
2014 character (such as Ctrl-A) followed by a carriage return and then delimiting
2015 the escape codes with this character.
2016 Any occurrences of that character in the prompt are not printed.
2017 By the way, don't blame me for
2018 this hack; it's derived from the original
2020 which did print the delimiter character so you were out of luck
2021 if you did not have any non-printing characters.
2023 Since Backslashes and other special characters may be
2024 interpreted by the shell, to set
2026 either escape the backslash itself,
2027 or use double quotes.
2028 The latter is more practical.
2029 This is a more complex example,
2030 avoiding to directly enter special characters (for example with
2032 in the emacs editing mode),
2033 which embeds the current working directory,
2035 .Pq colour would work, too ,
2036 in the prompt string:
2037 .Bd -literal -offset indent
2039 PS1="$x$(print \e\er)$x$(tput so)$x\e$PWD$x$(tput se)$x\*(Gt "
2042 Due to a strong suggestion from David G. Korn,
2044 now also supports the following form:
2045 .Bd -literal -offset indent
2046 PS1=$'\e1\er\e1\ee[7m\e1$PWD\e1\ee[0m\e1\*(Gt '
2049 Secondary prompt string, by default
2051 used when more input is needed to complete a command.
2055 statement when reading a menu selection.
2059 Used to prefix commands that are printed during execution tracing (see the
2062 Parameter, command, and arithmetic substitutions are performed
2063 before it is printed.
2066 You may want to set it to
2067 .Sq \&[$EPOCHREALTIME]\ \&
2068 instead, to include timestamps.
2070 The current working directory.
2073 if the shell doesn't know where it is.
2077 is referenced, it is assigned a number between 0 and 32767 from
2078 a Linear Congruential PRNG first.
2080 Default parameter for the
2082 command if no names are given.
2085 loops to store the value that is read from standard input.
2087 The number of seconds since the shell started or, if the parameter has been
2088 assigned an integer value, the number of seconds since the assignment plus the
2089 value that was assigned.
2091 If set to a positive integer in an interactive shell, it specifies the maximum
2092 number of seconds the shell will wait for input after printing the primary
2095 If the time is exceeded, the shell exits.
2097 The directory temporary shell files are created in.
2098 If this parameter is not
2099 set, or does not contain the absolute path of a writable directory, temporary
2100 files are created in
2103 The effective user id of the shell.
2106 Tilde expansion which is done in parallel with parameter substitution, is done
2107 on words starting with an unquoted
2109 The characters following the tilde, up to the first
2111 if any, are assumed to be a login name.
2112 If the login name is empty,
2121 parameter is substituted, respectively.
2122 Otherwise, the password file is
2123 searched for the login name, and the tilde expression is substituted with the
2124 user's home directory.
2125 If the login name is not found in the password file or
2126 if any quoting or parameter substitution occurs in the login name, no
2127 substitution is performed.
2129 In parameter assignments
2130 (such as those preceding a simple-command or those occurring
2138 tilde expansion is done after any assignment
2139 (i.e. after the equals sign)
2140 or after an unquoted colon
2142 login names are also delimited by colons.
2144 The home directory of previously expanded login names are cached and re-used.
2147 command may be used to list, change, and add to this cache (e.g.\&
2148 .Ic alias \-d fac=/usr/local/facilities; cd \*(TIfac/bin ) .
2149 .Ss Brace expansion (alternation)
2150 Brace expressions take the following form:
2151 .Bd -unfilled -offset indent
2154 .Ar prefix No { Ar str1 No ,...,
2155 .Ar strN No } Ar suffix
2160 The expressions are expanded to
2162 words, each of which is the concatenation of
2169 expands to four words:
2175 As noted in the example, brace expressions can be nested and the resulting
2176 words are not sorted.
2177 Brace expressions must contain an unquoted comma
2179 for expansion to occur (e.g.\&
2184 Brace expansion is carried out after parameter substitution
2185 and before file name generation.
2186 .Ss File name patterns
2187 A file name pattern is a word containing one or more unquoted
2197 Once brace expansion has been performed, the shell replaces file
2198 name patterns with the sorted names of all the files that match the pattern
2199 (if no files match, the word is left unchanged).
2200 The pattern elements have the following meaning:
2203 Matches any single character.
2205 Matches any sequence of octets.
2207 Matches any of the octets inside the brackets.
2208 Ranges of octets can be specified by separating two octets by a
2215 In order to represent itself, a
2217 must either be quoted or the first or last octet in the octet list.
2220 must be quoted or the first octet in the list if it is to represent itself
2221 instead of the end of the list.
2224 appearing at the start of the list has special meaning (see below), so to
2225 represent itself it must be quoted or appear later in the list.
2228 except it matches any octet not inside the brackets.
2230 .It *( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2232 Matches any string of octets that matches zero or more occurrences of the
2234 Example: The pattern
2243 .It +( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2245 Matches any string of octets that matches one or more occurrences of the
2247 Example: The pattern
2255 .It ?( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2257 Matches the empty string or a string that matches one of the specified
2259 Example: The pattern
2261 only matches the strings
2267 .It @( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2269 Matches a string that matches one of the specified patterns.
2270 Example: The pattern
2272 only matches the strings
2277 .It !( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2279 Matches any string that does not match one of the specified patterns.
2280 Examples: The pattern
2282 matches all strings except
2288 matches no strings; the pattern
2290 matches all strings (think about it).
2293 Note that complicated globbing, especially with alternatives,
2294 is slow; using separate comparisons may (or may not) be faster.
2312 Note that none of the above pattern elements match either a period
2314 at the start of a file name or a slash
2316 even if they are explicitly used in a [..] sequence; also, the names
2320 are never matched, even by the pattern
2325 option is set, any directories that result from file name generation are marked
2328 .Ss Input/output redirection
2329 When a command is executed, its standard input, standard output, and standard
2330 error (file descriptors 0, 1, and 2, respectively) are normally inherited from
2332 Three exceptions to this are commands in pipelines, for which
2333 standard input and/or standard output are those set up by the pipeline,
2334 asynchronous commands created when job control is disabled, for which standard
2335 input is initially set to be from
2337 and commands for which any of the following redirections have been specified:
2338 .Bl -tag -width XXxxmarker
2340 Standard output is redirected to
2344 does not exist, it is created; if it does exist, is a regular file, and the
2346 option is set, an error occurs; otherwise, the file is truncated.
2347 Note that this means the command
2348 .Ic cmd \*(Ltfoo \*(Gtfoo
2351 for reading and then truncate it when it opens it for writing, before
2353 gets a chance to actually read
2355 .It \*(Gt\*(Ba Ar file
2358 except the file is truncated, even if the
2361 .It \*(Gt\*(Gt Ar file
2366 exists it is appended to instead of being truncated.
2367 Also, the file is opened
2368 in append mode, so writes always go to the end of the file (see
2371 Standard input is redirected from
2373 which is opened for reading.
2374 .It \*(Lt\*(Gt Ar file
2377 except the file is opened for reading and writing.
2378 .It \*(Lt\*(Lt Ar marker
2379 After reading the command line containing this kind of redirection (called a
2380 .Dq here document ) ,
2381 the shell copies lines from the command source into a temporary file until a
2385 When the command is executed, standard input is redirected from the
2389 contains no quoted characters, the contents of the temporary file are processed
2390 as if enclosed in double quotes each time the command is executed, so
2391 parameter, command, and arithmetic substitutions are performed, along with
2402 If multiple here documents are used on the same command line, they are saved in
2407 is given, the here document ends at the next
2409 and substitution will be performed.
2412 is only a set of either single
2416 quotes with nothing in between, the here document ends at the next empty line
2417 and substitution will not be performed.
2418 .It \*(Lt\*(Lt\- Ar marker
2421 except leading tabs are stripped from lines in the here document.
2422 .It \*(Lt\*(Lt\*(Lt Ar word
2429 This is called a here string.
2431 Standard input is duplicated from file descriptor
2434 can be a number, indicating the number of an existing file descriptor;
2437 indicating the file descriptor associated with the output of the current
2438 co-process; or the character
2440 indicating standard input is to be closed.
2443 is limited to a single digit in most shell implementations.
2447 except the operation is done on standard output.
2450 .Ic \*(Gt Ar file 2\*(Gt&1 .
2453 extension supported by
2455 which also supports the preceding explicit fd number, for example,
2458 .Ic 3\*(Gt Ar file 2\*(Gt&3
2461 but a syntax error in GNU
2467 shell options disable parsing of this redirection;
2468 it's a compatibility feature to legacy scripts, to
2469 not be used when writing new shell code.
2471 .No &\*(Gt\*(Ba Ar file ,
2472 .No &\*(Gt\*(Gt Ar file ,
2476 .Ic \*(Gt\*(Ba Ar file ,
2477 .Ic \*(Gt\*(Gt Ar file ,
2488 In any of the above redirections, the file descriptor that is redirected
2489 (i.e. standard input or standard output)
2490 can be explicitly given by preceding the
2491 redirection with a number (portably, only a single digit).
2492 Parameter, command, and arithmetic
2493 substitutions, tilde substitutions, and (if the shell is interactive)
2494 file name generation are all performed on the
2499 arguments of redirections.
2500 Note, however, that the results of any file name
2501 generation are only used if a single file is matched; if multiple files match,
2502 the word with the expanded file name generation characters is used.
2504 that in restricted shells, redirections which can create files cannot be used.
2506 For simple-commands, redirections may appear anywhere in the command; for
2512 any redirections must appear at the end.
2513 Redirections are processed after
2514 pipelines are created and in the order they are given, so the following
2515 will print an error with a line number prepended to it:
2517 .D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt/dev/null \*(Ba pr \-n \-t
2519 File descriptors created by input/output redirections are private to the
2520 Korn shell, but passed to sub-processes if
2525 .Ss Arithmetic expressions
2526 Integer arithmetic expressions can be used with the
2528 command, inside $((..)) expressions, inside array references (e.g.\&
2529 .Ar name Ns Bq Ar expr ) ,
2530 as numeric arguments to the
2532 command, and as the value of an assignment to an integer parameter.
2534 This also affects implicit conversion to integer, for example as done by the
2538 use unchecked user input, e.g. from the environment, in arithmetics!
2540 Expressions are calculated using signed arithmetic and the
2542 type (a 32-bit signed integer), unless they begin with a sole
2544 character, in which case they use
2546 .Po a 32-bit unsigned integer Pc .
2548 Expressions may contain alpha-numeric parameter identifiers, array references,
2549 and integer constants and may be combined with the following C operators
2550 (listed and grouped in increasing order of precedence):
2553 .Bd -literal -offset indent
2554 + \- ! \*(TI ++ \-\-
2558 .Bd -literal -offset indent
2560 = += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt= \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
2567 \*(Lt \*(Lt= \*(Gt \*(Gt=
2568 \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt \*(Lt\*(Lt \*(Gt\*(Gt
2574 .Bd -literal -offset indent
2575 ?: (precedence is immediately higher than assignment)
2579 .Bd -literal -offset indent
2583 Integer constants and expressions are calculated using an exactly 32-bit
2584 wide, signed or unsigned, type with silent wraparound on integer overflow.
2585 Integer constants may be specified with arbitrary bases using the notation
2586 .Ar base Ns # Ns Ar number ,
2589 is a decimal integer specifying the base, and
2591 is a number in the specified base.
2592 Additionally, base-16 integers may be specified by prefixing them with
2594 .Pq case-insensitive
2595 in all forms of arithmetic expressions, except as numeric arguments to the
2598 Prefixing numbers with a sole digit zero
2600 leads to the shell interpreting it as base-8 (octal) integer in
2604 historically, (pd)ksh has never done so either anyway,
2605 and it's unsafe to do that, but POSIX demands it nowadays.
2608 extension, numbers to the base of one are treated as either (8-bit
2609 transparent) ASCII or Unicode codepoints, depending on the shell's
2611 flag (current setting).
2620 Note that NUL bytes (integral value of zero) cannot be used.
2621 An unset or empty parameter evaluates to 0 in integer context.
2622 In Unicode mode, raw octets are mapped into the range EF80..EFFF as in
2623 OPTU-8, which is in the PUA and has been assigned by CSUR for this use.
2624 If more than one octet in ASCII mode, or a sequence of more than one
2625 octet not forming a valid and minimal CESU-8 sequence is passed, the
2626 behaviour is undefined (usually, the shell aborts with a parse error,
2627 but rarely, it succeeds, e.g. on the sequence C2 20).
2628 That's why you should always use ASCII mode unless you know that the
2629 input is well-formed UTF-8 in the range of 0000..FFFD.
2631 The operators are evaluated as follows:
2632 .Bl -tag -width Ds -offset indent
2634 Result is the argument (included for completeness).
2639 the result is 1 if argument is zero, 0 if not.
2641 Arithmetic (bit-wise) NOT.
2643 Increment; must be applied to a parameter (not a literal or other expression).
2644 The parameter is incremented by 1.
2645 When used as a prefix operator, the result
2646 is the incremented value of the parameter; when used as a postfix operator, the
2647 result is the original value of the parameter.
2651 except the parameter is decremented by 1.
2653 Separates two arithmetic expressions; the left-hand side is evaluated first,
2655 The result is the value of the expression on the right-hand side.
2657 Assignment; the variable on the left is set to the value on the right.
2659 .No += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt=
2660 .No \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
2662 Assignment operators.
2677 with any operator precedence in
2682 is the same as specifying
2683 .Dq var1 = var1 * (5 + 3) .
2686 the result is 1 if either argument is non-zero, 0 if not.
2687 The right argument is evaluated only if the left argument is zero.
2690 the result is 1 if both arguments are non-zero, 0 if not.
2691 The right argument is evaluated only if the left argument is non-zero.
2693 Arithmetic (bit-wise) OR.
2695 Arithmetic (bit-wise) XOR
2698 Arithmetic (bit-wise) AND.
2700 Equal; the result is 1 if both arguments are equal, 0 if not.
2702 Not equal; the result is 0 if both arguments are equal, 1 if not.
2704 Less than; the result is 1 if the left argument is less than the right, 0 if
2706 .It \*(Lt= \*(Gt \*(Gt=
2707 Less than or equal, greater than, greater than or equal.
2710 .It \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt
2711 Rotate left (right); the result is similar to shift (see
2713 except that the bits shifted out at one end are shifted in
2714 at the other end, instead of zero or sign bits.
2715 .It \*(Lt\*(Lt \*(Gt\*(Gt
2716 Shift left (right); the result is the left argument with its bits shifted left
2717 (right) by the amount given in the right argument.
2719 Addition, subtraction, multiplication, and division.
2721 Remainder; the result is the symmetric remainder of the division of the left
2722 argument by the right.
2723 To get the mathematical modulus of
2739 is non-zero, the result is
2741 otherwise the result is
2743 The non-result argument is not evaluated.
2746 A co-process (which is a pipeline created with the
2748 operator) is an asynchronous process that the shell can both write to (using
2750 and read from (using
2752 The input and output of the co-process can also be manipulated using
2756 redirections, respectively.
2757 Once a co-process has been started, another can't
2758 be started until the co-process exits, or until the co-process's input has been
2760 .Ic exec Ar n Ns Ic \*(Gt&p
2762 If a co-process's input is redirected in this way, the next
2763 co-process to be started will share the output with the first co-process,
2764 unless the output of the initial co-process has been redirected using an
2765 .Ic exec Ar n Ns Ic \*(Lt&p
2768 Some notes concerning co-processes:
2771 The only way to close the co-process's input (so the co-process reads an
2772 end-of-file) is to redirect the input to a numbered file descriptor and then
2773 close that file descriptor:
2774 .Ic exec 3\*(Gt&p; exec 3\*(Gt&\-
2776 In order for co-processes to share a common output, the shell must keep the
2777 write portion of the output pipe open.
2778 This means that end-of-file will not be
2779 detected until all co-processes sharing the co-process's output have exited
2780 (when they all exit, the shell closes its copy of the pipe).
2782 avoided by redirecting the output to a numbered file descriptor (as this also
2783 causes the shell to close its copy).
2784 Note that this behaviour is slightly
2785 different from the original Korn shell which closes its copy of the write
2786 portion of the co-process output when the most recently started co-process
2787 (instead of when all sharing co-processes) exits.
2792 signals during writes if the signal is not being trapped or ignored; the same
2793 is true if the co-process input has been duplicated to another file descriptor
2795 .Ic print Fl u Ns Ar n
2799 Functions are defined using either Korn shell
2800 .Ic function Ar function-name
2801 syntax or the Bourne/POSIX shell
2802 .Ar function-name Ns \&()
2803 syntax (see below for the difference between the two forms).
2806 (i.e. scripts sourced using the
2809 in that they are executed in the current environment.
2812 shell arguments (i.e. positional parameters $1, $2, etc.)\&
2813 are never visible inside them.
2814 When the shell is determining the location of a command, functions
2815 are searched after special built-in commands, before builtins and the
2819 An existing function may be deleted using
2820 .Ic unset Fl f Ar function-name .
2821 A list of functions can be obtained using
2823 and the function definitions can be listed using
2827 command (which is an alias for
2829 may be used to create undefined functions: when an undefined function is
2830 executed, the shell searches the path specified in the
2832 parameter for a file with the same name as the function which, if found, is
2834 If after executing the file the named function is found to
2835 be defined, the function is executed; otherwise, the normal command search is
2836 continued (i.e. the shell searches the regular built-in command table and
2838 Note that if a command is not found using
2840 an attempt is made to autoload a function using
2842 (this is an undocumented feature of the original Korn shell).
2844 Functions can have two attributes,
2848 which can be set with
2853 When a traced function is executed, the shell's
2855 option is turned on for the function's duration.
2858 attribute of functions is currently not used.
2859 In the original Korn shell,
2860 exported functions are visible to shell scripts that are executed.
2862 Since functions are executed in the current shell environment, parameter
2863 assignments made inside functions are visible after the function completes.
2864 If this is not the desired effect, the
2866 command can be used inside a function to create a local parameter.
2870 uses static scoping (one global scope, one local scope per function)
2871 and allows local variables only on Korn style functions, whereas
2873 uses dynamic scoping (nested scopes of varying locality).
2874 Note that special parameters (e.g.\&
2876 can't be scoped in this way.
2878 The exit status of a function is that of the last command executed in the
2880 A function can be made to finish immediately using the
2882 command; this may also be used to explicitly specify the exit status.
2884 Functions defined with the
2886 reserved word are treated differently in the following ways from functions
2892 The $0 parameter is set to the name of the function
2893 (Bourne-style functions leave $0 untouched).
2895 Parameter assignments preceding function calls are not kept in the shell
2896 environment (executing Bourne-style functions will keep assignments).
2899 is saved/reset and restored on entry and exit from the function so
2901 can be used properly both inside and outside the function (Bourne-style
2906 inside a function interferes with using
2908 outside the function).
2912 have local scope, i.e. changes inside a function are reset upon its exit.
2915 In the future, the following differences may also be added:
2918 A separate trap/signal environment will be used during the execution of
2920 This will mean that traps set inside a function will not affect the
2921 shell's traps and signals that are not ignored in the shell (but may be
2922 trapped) will have their default effect in a function.
2924 The EXIT trap, if set in a function, will be executed after the function
2927 .Ss Command execution
2928 After evaluation of command-line arguments, redirections, and parameter
2929 assignments, the type of command is determined: a special built-in command,
2930 a function, a normal builtin, or the name of a file to execute found using the
2933 The checks are made in the above order.
2934 Special built-in commands differ from other commands in that the
2936 parameter is not used to find them, an error during their execution can
2937 cause a non-interactive shell to exit, and parameter assignments that are
2938 specified before the command are kept after the command completes.
2939 Regular built-in commands are different only in that the
2941 parameter is not used to find them.
2945 and POSIX differ somewhat in which commands are considered
2948 POSIX special built-in utilities:
2950 .Ic \&. , \&: , break , continue ,
2951 .Ic eval , exec , exit , export ,
2952 .Ic readonly , return , set , shift ,
2953 .Ic times , trap , unset
2957 commands keeping assignments:
2959 .Ic builtin , global , typeset , wait
2961 Builtins that are not special:
2963 .Ic [ , alias , bg , bind ,
2964 .Ic cat , cd , command , echo ,
2965 .Ic false , fc , fg , getopts ,
2966 .Ic jobs , kill , let , mknod ,
2967 .Ic print , pwd , read , realpath ,
2968 .Ic rename , sleep , suspend , test ,
2969 .Ic true , ulimit , umask , unalias ,
2972 Once the type of command has been determined, any command-line parameter
2973 assignments are performed and exported for the duration of the command.
2975 The following describes the special and regular built-in commands:
2977 .Bl -tag -width false -compact
2978 .It Ic \&. Ar file Op Ar arg ...
2982 Execute the commands in
2984 in the current environment.
2985 The file is searched for in the directories of
2987 If arguments are given, the positional parameters may be used to access them
2991 If no arguments are given, the positional parameters are
2992 those of the environment the command is used in.
2994 .It Ic \&: Op Ar ...
2996 Exit status is set to zero.
2998 .It Ic \&[ Ar expression Ic \&]
3003 .Oo Fl d \*(Ba t Oo Fl r Oc \*(Ba
3008 .Op Ns = Ns Ar value
3014 For any name without a value, the existing alias is listed.
3015 Any name with a value defines an alias (see
3019 When listing aliases, one of two formats is used.
3020 Normally, aliases are listed as
3021 .Ar name Ns = Ns Ar value ,
3025 If options were preceded with
3029 is given on the command line, only
3035 option causes directory aliases which are used in tilde expansion to be
3042 option is used, each alias is prefixed with the string
3047 option indicates that tracked aliases are to be listed/set (values specified on
3048 the command line are ignored for tracked aliases).
3051 option indicates that all tracked aliases are to be reset.
3057 the export attribute of an alias, or, if no names are given, lists the aliases
3058 with the export attribute (exporting an alias has no effect).
3060 .It Ic bg Op Ar job ...
3061 Resume the specified stopped job(s) in the background.
3062 If no jobs are specified,
3067 below for more information.
3070 The current bindings are listed.
3075 instead lists the names of the functions to which keys may be bound.
3077 .Sx Emacs editing mode
3078 for more information.
3080 .It Xo Ic bind Op Fl m
3081 .Ar string Ns = Ns Op Ar substitute
3085 .Ar string Ns = Ns Op Ar editing-command
3088 The specified editing command is bound to the given
3090 which should consist of a control character
3091 optionally preceded by one of the two prefix characters
3092 and optionally succeded by a tilde character.
3095 will cause the editing command to be immediately invoked.
3098 flag is given, the specified input
3100 will afterwards be immediately replaced by the given
3102 string which may contain editing commands but not other macros.
3103 If a tilde postfix is given, a tilde trailing the one or
3104 two prefices and the control character is ignored, any
3105 other trailing character will be processed afterwards.
3107 Control characters may be written using caret notation
3108 i.e. \*(haX represents Ctrl-X.
3109 Note that although only two prefix characters (usually ESC and \*(haX)
3110 are supported, some multi-character sequences can be supported.
3112 The following default bindings show how the arrow keys, the home, end and
3113 delete key on a BSD wsvt25, xterm\-xfree86 or GNU screen terminal are bound
3114 (of course some escape sequences won't work out quite this nicely):
3115 .Bd -literal -offset indent
3116 bind \*(aq\*(haX\*(aq=prefix\-2
3117 bind \*(aq\*(ha[[\*(aq=prefix\-2
3118 bind \*(aq\*(haXA\*(aq=up\-history
3119 bind \*(aq\*(haXB\*(aq=down\-history
3120 bind \*(aq\*(haXC\*(aq=forward\-char
3121 bind \*(aq\*(haXD\*(aq=backward\-char
3122 bind \*(aq\*(haX1\*(TI\*(aq=beginning\-of\-line
3123 bind \*(aq\*(haX7\*(TI\*(aq=beginning\-of\-line
3124 bind \*(aq\*(haXH\*(aq=beginning\-of\-line
3125 bind \*(aq\*(haX4\*(TI\*(aq=end\-of\-line
3126 bind \*(aq\*(haX8\*(TI\*(aq=end\-of\-line
3127 bind \*(aq\*(haXF\*(aq=end\-of\-line
3128 bind \*(aq\*(haX3\*(TI\*(aq=delete\-char\-forward
3131 .It Ic break Op Ar level
3147 .Ar command Op Ar arg ...
3149 Execute the built-in command
3157 Read files sequentially, in command line order, and write them to
3163 or absent, read from standard input.
3164 For direct builtin calls, the
3167 option is supported as a no-op.
3168 For calls from shell, if any options are given, an external
3170 utility is preferred over the builtin.
3187 Set the working directory to
3191 is set, it lists the search path for the directory containing
3195 path means the current directory.
3198 is found in any component of the
3200 search path other than the
3202 path, the name of the new working directory will be written to standard output.
3205 is missing, the home directory
3212 the previous working directory is used (see the
3218 option (logical path) is used or if the
3220 option isn't set (see the
3222 command below), references to
3226 are relative to the path used to get to the directory.
3229 option (physical path) is used or if the
3233 is relative to the filesystem directory tree.
3238 parameters are updated to reflect the current and old working directory,
3242 option is set for physical filesystem traversal, and
3244 could not be set, the exit code is 1; greater than 1 if an
3245 error occurred, 0 otherwise.
3261 in the current directory, and the shell attempts to change to the new
3276 is executed exactly as if
3278 had not been specified, with two exceptions:
3281 cannot be a shell function;
3282 and secondly, special built-in commands lose their specialness
3283 (i.e. redirection and utility errors do not cause the shell to
3284 exit, and command assignments are not permanent).
3288 option is given, a default search path is used instead of the current value of
3290 the actual value of which is system dependent.
3294 option is given, instead of executing
3296 information about what would be executed is given (and the same is done for
3298 For builtins, functions and keywords, their names are simply printed;
3299 for aliases, a command that defines them is printed;
3300 for utilities found by searching the
3302 parameter, the full path of the command is printed.
3303 If no command is found
3304 (i.e. the path search fails), nothing is printed and
3306 exits with a non-zero status.
3311 option, except it is more verbose.
3313 .It Ic continue Op Ar level
3314 Jumps to the beginning of the
3332 this utility is not portable; use the Korn shell builtin
3336 Prints its arguments (separated by spaces) followed by a newline, to the
3338 The newline is suppressed if any of the arguments contain the
3343 command below for a list of other backslash sequences that are recognised.
3345 The options are provided for compatibility with
3350 option suppresses the trailing newline,
3352 enables backslash interpretation (a no-op, since this is normally done), and
3354 suppresses backslash interpretation.
3360 option is set or this is a direct builtin call, only the first argument
3361 is treated as an option, and only if it is exactly
3363 Backslash interpretation is disabled.
3365 .It Ic eval Ar command ...
3366 The arguments are concatenated (with spaces between them) to form a single
3367 string which the shell then parses and executes in the current environment.
3373 .Op Ar command Op Ar arg ...
3375 The command is executed without forking, replacing the shell process.
3376 This is currently absolute, i.e.\&
3378 never returns, even if the
3383 option permits setting a different
3387 clears the environment before executing the child process, except for the
3389 variable and direct assignments.
3391 If no command is given except for I/O redirection, the I/O redirection is
3392 permanent and the shell is
3394 Any file descriptors greater than 2 which are opened or
3396 in this way are not made available to other executed commands (i.e. commands
3397 that are not built-in to the shell).
3398 Note that the Bourne shell differs here;
3399 it does pass these file descriptors on.
3401 .It Ic exit Op Ar status
3402 The shell exits with the specified exit status.
3405 is not specified, the exit status is the current value of the
3412 .Op Ar parameter Ns Op = Ns Ar value
3414 Sets the export attribute of the named parameters.
3415 Exported parameters are passed in the environment to executed commands.
3416 If values are specified, the named parameters are also assigned.
3418 If no parameters are specified, all parameters with the export attribute
3419 set are printed one per line; either their names, or, if a
3421 with no option letter is specified, name=value pairs, or, with
3424 commands suitable for re-entry.
3427 A command that exits with a non-zero status.
3431 .Oo Fl e Ar editor \*(Ba
3434 .Op Ar first Op Ar last
3439 select commands from the history.
3440 Commands can be selected by history number
3441 (negative numbers go backwards from the current, most recent, line)
3442 or a string specifying the most recent command starting with that string.
3445 option lists the command on standard output, and
3447 inhibits the default command numbers.
3450 option reverses the order of the list.
3453 the selected commands are edited by the editor specified with the
3457 is specified, the editor specified by the
3459 parameter (if this parameter is not set,
3461 is used), and then executed by the shell.
3465 .Cm \-e \- \*(Ba Fl s
3467 .Op Ar old Ns = Ns Ar new
3470 Re-execute the selected command (the previous command by default) after
3471 performing the optional substitution of
3477 is specified, all occurrences of
3485 is identical: re-execute the selected command without invoking an editor.
3486 This command is usually accessed with the predefined:
3487 .Ic alias r=\*(aqfc \-e \-\*(aq
3489 .It Ic fg Op Ar job ...
3490 Resume the specified job(s) in the foreground.
3491 If no jobs are specified,
3496 below for more information.
3503 Used by shell procedures to parse the specified arguments (or positional
3504 parameters, if no arguments are given) and to check for legal options.
3506 contains the option letters that
3509 If a letter is followed by a colon, the option is expected to
3511 Options that do not take arguments may be grouped in a single argument.
3512 If an option takes an argument and the option character is not the
3513 last character of the argument it is found in, the remainder of the argument is
3514 taken to be the option's argument; otherwise, the next argument is the option's
3519 is invoked, it places the next option in the shell parameter
3521 and the index of the argument to be processed by the next call to
3523 in the shell parameter
3525 If the option was introduced with a
3527 the option placed in
3531 When an option requires an argument,
3533 places it in the shell parameter
3536 When an illegal option or a missing option argument is encountered, a question
3537 mark or a colon is placed in
3539 (indicating an illegal option or missing argument, respectively) and
3541 is set to the option character that caused the problem.
3544 does not begin with a colon, a question mark is placed in
3547 is unset, and an error message is printed to standard error.
3549 When the end of the options is encountered,
3551 exits with a non-zero exit status.
3552 Options end at the first (non-option
3553 argument) argument that does not start with a
3557 argument is encountered.
3559 Option parsing can be reset by setting
3561 to 1 (this is done automatically whenever the shell or a shell procedure is
3564 Warning: Changing the value of the shell parameter
3566 to a value other than 1, or parsing different sets of arguments without
3569 may lead to unexpected results.
3580 Without arguments, any hashed executable command pathnames are listed.
3583 option causes all hashed commands to be removed from the hash table.
3586 is searched as if it were a command name and added to the hash table if it is
3587 an executable command.
3594 Display information about the specified job(s); if no jobs are specified, all
3598 option causes information to be displayed only for jobs that have changed
3599 state since the last notification.
3602 option is used, the process ID of each process in a job is also listed.
3605 option causes only the process group of each job to be printed.
3608 below for the format of
3610 and the displayed job.
3614 .Oo Fl s Ar signame \*(Ba
3615 .No \- Ns Ar signum \*(Ba
3616 .No \- Ns Ar signame Oc
3617 .No { Ar job \*(Ba pid \*(Ba pgrp No }
3620 Send the specified signal to the specified jobs, process IDs, or process
3622 If no signal is specified, the
3625 If a job is specified, the signal is sent to the job's process group.
3628 below for the format of
3634 .Op Ar exit-status ...
3636 Print the signal name corresponding to
3638 If no arguments are specified, a list of all the signals, their numbers, and
3639 a short description of them are printed.
3641 .It Ic let Op Ar expression ...
3642 Each expression is evaluated (see
3643 .Sx Arithmetic expressions
3645 If all expressions are successfully evaluated, the exit status is 0 (1)
3646 if the last expression evaluated to non-zero (zero).
3647 If an error occurs during
3648 the parsing or evaluation of an expression, the exit status is greater than 1.
3649 Since expressions may need to be quoted,
3650 .No \&(( Ar expr No ))
3651 is syntactic sugar for
3652 .No let \&" Ns Ar expr Ns \&" .
3655 Internally used alias for
3671 Create a device special file.
3672 The file type may be
3674 (block type device),
3676 (character type device),
3679 .Pq named pipe , Tn FIFO .
3680 The file created may be modified according to its
3686 (major device number),
3689 (minor device number).
3693 for further information.
3694 This is not normally part of
3696 however, distributors may have added this as builtin as a speed hack.
3700 .Oo Fl nprsu Ns Oo Ar n Oc \*(Ba
3705 prints its arguments on the standard output, separated by spaces and
3706 terminated with a newline.
3709 option suppresses the newline.
3710 By default, certain C escapes are translated.
3711 These include these mentioned in
3712 .Sx Backslash expansion
3715 which is equivalent to using the
3718 Backslash expansion may be inhibited with the
3723 option prints to the history file instead of standard output; the
3725 option prints to file descriptor
3729 defaults to 1 if omitted
3733 option prints to the co-process (see
3739 option is used to emulate, to some degree, the
3742 command which does not process
3744 sequences unless the
3749 option suppresses the trailing newline.
3751 .It Ic printf Ar format Op Ar arguments ...
3753 Approximately the same as the
3755 utility, except it uses the same
3756 .Sx Backslash expansion
3757 and I/O code and does not handle floating point as the rest of
3759 An external utility is preferred over the builtin.
3760 This is not normally part of
3762 however, distributors may have added this as builtin as a speed hack.
3763 Do not use in new code.
3766 Print the present working directory.
3769 option is used or if the
3771 option isn't set (see the
3773 command below), the logical path is printed (i.e. the path used to
3775 to the current directory).
3778 option (physical path) is used or if the
3780 option is set, the path determined from the filesystem (by following
3782 directories to the root directory) is printed.
3796 Reads a line of input, separates the input into fields using the
3800 above), and assigns each field to the specified parameters
3802 If no parameters are specified, the
3804 parameter is used to store the result.
3809 options, only no or one parameter is accepted.
3810 If there are more parameters than fields, the extra parameters are set to
3811 the empty string or 0; if there are more fields than parameters, the last
3812 parameter is assigned the remaining fields (including the word separators).
3814 The options are as follows:
3815 .Bl -tag -width XuXnX
3817 Store the result into the parameter
3823 Store the result without word splitting into the parameter
3827 as array of characters (wide characters if the
3829 option is enacted, octets otherwise).
3831 Use the first byte of
3834 if empty, instead of the ASCII newline character as input line delimiter.
3836 Instead of reading till end-of-line, read exactly
3839 If EOF or a timeout occurs, a partial read is returned with exit status 1.
3841 Instead of reading till end-of-line, read up to
3843 bytes but return as soon as any bytes are read, e.g.\& from a
3844 slow terminal device, or if EOF or a timeout occurs.
3846 Read from the currently active co-process, see
3848 above for details on this.
3850 Read from the file descriptor
3852 (defaults to 0, i.e.\& standard input).
3853 The argument must immediately follow the option character.
3855 Interrupt reading after
3857 seconds (specified as positive decimal value with an optional fractional part).
3860 is 1 if the timeout occurred, but partial reads may still be returned.
3862 Normally, the ASCII backslash character escapes the special
3863 meaning of the following character and is stripped from the input;
3865 does not stop when encountering a backslash-newline sequence and
3866 does not store that newline in the result.
3867 This option enables raw mode, in which backslashes are not processed.
3869 The input line is saved to the history.
3872 If the input is a terminal, both the
3876 options set it into raw mode;
3877 they read an entire file if \-1 is passed as
3881 The first parameter may have a question mark and a string appended to it, in
3882 which case the string is used as a prompt (printed to standard error before
3883 any input is read) if the input is a
3886 .Ic read nfoo?\*(aqnumber of foos: \*(aq ) .
3888 If no input is read or a timeout occurred,
3890 exits with a non-zero status.
3892 Another handy set of tricks:
3895 is run in a loop such as
3896 .Ic while read foo; do ...; done
3897 then leading whitespace will be removed (IFS) and backslashes processed.
3898 You might want to use
3899 .Ic while IFS= read \-r foo; do ...; done
3901 Similarily, when using the
3905 option might be prudent; the same applies for:
3906 .Bd -literal -offset indent
3907 find . \-type f \-print0 \*(Ba& \e
3908 while IFS= read \-d \*(aq\*(aq \-pr filename; do
3909 print \-r \-\- "found \*(Lt${filename#./}\*(Gt"
3913 The inner loop will be executed in a subshell and variable changes
3914 cannot be propagated if executed in a pipeline:
3915 .Bd -literal -offset indent
3916 bar \*(Ba baz \*(Ba while read foo; do ...; done
3919 Use co-processes instead:
3920 .Bd -literal -offset indent
3921 bar \*(Ba baz \*(Ba&
3922 while read \-p foo; do ...; done
3923 exec 3\*(Gt&p; exec 3\*(Gt&\-
3930 .Op Ns = Ns Ar value
3933 Sets the read-only attribute of the named parameters.
3934 If values are given,
3935 parameters are set to them before setting the attribute.
3937 made read-only, it cannot be unset and its value cannot be changed.
3939 If no parameters are specified, the names of all parameters with the read-only
3940 attribute are printed one per line, unless the
3942 option is used, in which case
3944 commands defining all read-only parameters, including their values, are
3952 Prints the resolved absolute pathname corresponding to
3958 it's also checked for existence and whether it is a directory; otherwise,
3960 returns 0 if the pathname either exists or can be created immediately,
3961 i.e. all but the last component exist and are directories.
3972 Both must be complete pathnames and on the same device.
3973 This builtin is intended for emergency situations where
3975 becomes unusable, and directly calls
3978 .It Ic return Op Ar status
3979 Returns from a function or
3981 script, with exit status
3985 is given, the exit status of the last executed command is used.
3986 If used outside of a function or
3988 script, it has the same effect as
3992 treats both profile and
3996 scripts, while the original Korn shell only treats profiles as
4001 .Ic set Op Ic +\-abCefhiklmnprsUuvXx
4002 .Op Ic +\-o Ar option
4009 command can be used to set
4013 shell options, set the positional parameters, or set an array parameter.
4014 Options can be changed using the
4018 is the long name of an option, or using the
4019 .Cm +\- Ns Ar letter
4022 is the option's single letter name (not all options have a single letter name).
4023 The following table lists both option letters (if they exist) and long names
4024 along with a description of what the option does:
4027 Sets the elements of the array parameter
4033 is used, the array is reset (i.e. emptied) first; if
4035 is used, the first N elements are set (where N is the number of arguments);
4036 the rest are left untouched.
4038 An alternative syntax for the command
4039 .Ic set \-A foo \-\- a b c
4040 which is compatible to
4043 and also supported by
4047 .Ic foo=(a b c); foo+=(d e)
4048 .It Fl a \*(Ba Fl o Ic allexport
4049 All new parameters are created with the export attribute.
4050 .It Fl b \*(Ba Fl o Ic notify
4051 Print job notification messages asynchronously, instead of just before the
4053 Only used if job control is enabled
4055 .It Fl C \*(Ba Fl o Ic noclobber
4056 Prevent \*(Gt redirection from overwriting existing files.
4057 Instead, \*(Gt\*(Ba must be used to force an overwrite.
4058 Note that this is not safe to use for creation of temporary files or
4059 lockfiles due to a TOCTOU in a check allowing one to redirect output to
4061 or other device files even in
4064 .It Fl e \*(Ba Fl o Ic errexit
4065 Exit (after executing the
4067 trap) as soon as an error occurs or a command fails (i.e. exits with a
4069 This does not apply to commands whose exit status is
4070 explicitly tested by a shell construct such as
4081 only the status of the last command is tested.
4082 .It Fl f \*(Ba Fl o Ic noglob
4083 Do not expand file name patterns.
4084 .It Fl h \*(Ba Fl o Ic trackall
4085 Create tracked aliases for all executed commands (see
4088 Enabled by default for non-interactive shells.
4089 .It Fl i \*(Ba Fl o Ic interactive
4090 The shell is an interactive shell.
4091 This option can only be used when the shell is invoked.
4092 See above for a description of what this means.
4093 .It Fl k \*(Ba Fl o Ic keyword
4094 Parameter assignments are recognised anywhere in a command.
4095 .It Fl l \*(Ba Fl o Ic login
4096 The shell is a login shell.
4097 This option can only be used when the shell is invoked.
4098 See above for a description of what this means.
4099 .It Fl m \*(Ba Fl o Ic monitor
4100 Enable job control (default for interactive shells).
4101 .It Fl n \*(Ba Fl o Ic noexec
4102 Do not execute any commands.
4103 Useful for checking the syntax of scripts
4104 (ignored if interactive).
4105 .It Fl p \*(Ba Fl o Ic privileged
4106 The shell is a privileged shell.
4107 It is set automatically if, when the shell starts,
4108 the real UID or GID does not match
4109 the effective UID (EUID) or GID (EGID), respectively.
4110 See above for a description of what this means.
4111 .It Fl r \*(Ba Fl o Ic restricted
4112 The shell is a restricted shell.
4113 This option can only be used when the shell is invoked.
4114 See above for a description of what this means.
4115 .It Fl s \*(Ba Fl o Ic stdin
4116 If used when the shell is invoked, commands are read from standard input.
4117 Set automatically if the shell is invoked with no arguments.
4123 command it causes the specified arguments to be sorted before assigning them to
4124 the positional parameters (or to array
4129 .It Fl U \*(Ba Fl o Ic utf8\-mode
4130 Enable UTF-8 support in the
4131 .Sx Emacs editing mode
4132 and internal string handling functions.
4133 This flag is disabled by default, but can be enabled by setting it on the
4134 shell command line; is enabled automatically for interactive shells if
4135 requested at compile time, your system supports
4136 .Fn setlocale LC_CTYPE \&""
4138 .Fn nl_langinfo CODESET ,
4144 environment variables,
4145 and at least one of these returns something that matches
4149 case-insensitively; for direct builtin calls depending on the
4150 aforementioned environment variables; or for stdin or scripts,
4151 if the input begins with a UTF-8 Byte Order Mark.
4152 .It Fl u \*(Ba Fl o Ic nounset
4153 Referencing of an unset parameter, other than
4157 is treated as an error, unless one of the
4163 .It Fl v \*(Ba Fl o Ic verbose
4164 Write shell input to standard error as it is read.
4165 .It Fl X \*(Ba Fl o Ic markdirs
4166 Mark directories with a trailing
4168 during file name generation.
4169 .It Fl x \*(Ba Fl o Ic xtrace
4170 Print command trees when they are executed, preceded by
4174 Background jobs are run with lower priority.
4175 .It Fl o Ic braceexpand
4176 Enable brace expansion (a.k.a. alternation).
4177 This is enabled by default.
4178 If disabled, tilde expansion after an equals sign is disabled as a side effect.
4180 Enable BRL emacs-like command-line editing (interactive shells only); see
4181 .Sx Emacs editing mode .
4183 Enable gmacs-like command-line editing (interactive shells only).
4184 Currently identical to emacs editing except that transpose\-chars (\*(haT) acts
4185 slightly differently.
4186 .It Fl o Ic ignoreeof
4187 The shell will not (easily) exit when end-of-file is read;
4190 To avoid infinite loops, the shell will exit if
4192 is read 13 times in a row.
4193 .It Fl o Ic inherit\-xtrace
4196 upon entering functions.
4197 This is enabled by default.
4199 Do not kill running jobs with a
4201 signal when a login shell exits.
4202 Currently set by default, but this may
4203 change in the future to be compatible with
4207 doesn't have this option, but does send the
4212 In the original Korn shell, this prevents function definitions from
4213 being stored in the history file.
4214 .It Fl o Ic physical
4221 (i.e. the filesystem's)
4223 directories instead of
4225 directories (i.e. the shell handles
4227 which allows the user to be oblivious of symbolic links to directories).
4229 Note that setting this option does not affect the current value of the
4239 commands above for more details.
4240 .It Fl o Ic pipefail
4241 Make the exit status of a pipeline (before logically complementing) the
4242 rightmost non-zero errorlevel, or zero if all commands exited with zero.
4244 Enable a somewhat more
4247 As a side effect, setting this flag turns off
4249 mode, which can be turned back on manually, and
4257 Automatically enabled if the basename of the shell invocation begins with
4259 and this autodetection feature is compiled in
4261 As a side effect, setting this flag turns off
4263 mode, which can be turned back on manually, and
4269 command-line editing (interactive shells only).
4272 for documentation and limitations.
4273 .It Fl o Ic vi\-esccomplete
4274 In vi command-line editing, do command and file name completion when escape
4275 (\*(ha[) is entered in command mode.
4276 .It Fl o Ic vi\-tabcomplete
4277 In vi command-line editing, do command and file name completion when tab (\*(haI)
4278 is entered in insert mode.
4279 This is the default.
4282 In the original Korn shell, unless
4284 was set, the vi command-line mode would let the
4286 driver do the work until ESC (\*(ha[) was entered.
4288 is always in viraw mode.
4291 These options can also be used upon invocation of the shell.
4293 options (with single letter names) can be found in the parameter
4296 with no option name will list all the options and whether each is on or off;
4298 will print the long names of all options that are currently on.
4300 Remaining arguments, if any, are positional parameters and are assigned, in
4301 order, to the positional parameters (i.e. $1, $2, etc.).
4304 and there are no remaining arguments, all positional parameters are cleared.
4305 If no options or arguments are given, the values of all names are printed.
4306 For unknown historical reasons, a lone
4308 option is treated specially \*(en it clears both the
4314 .It Ic shift Op Ar number
4315 The positional parameters
4325 .It Ic sleep Ar seconds
4326 Suspends execution for a minimum of the
4328 specified as positive decimal value with an optional fractional part.
4329 Signal delivery may continue execution earlier.
4331 .It Ic source Ar file Op Ar arg ...
4333 .Ic \&. Po Do dot Dc Pc ,
4334 except that the current working directory is appended to the
4344 this is implemented as a shell alias instead of a builtin.
4347 Stops the shell as if it had received the suspend character from
4349 It is not possible to suspend a login shell unless the parent process
4350 is a member of the same terminal session but is a member of a different
4352 As a general rule, if the shell was started by another shell or via
4354 it can be suspended.
4356 .It Ic test Ar expression
4357 .It Ic \&[ Ar expression Ic \&]
4361 and returns zero status if true, 1 if false, or greater than 1 if there
4363 It is normally used as the condition command of
4368 Symbolic links are followed for all
4375 The following basic expressions are available:
4382 is a block special device.
4385 is a character special device.
4397 group is the shell's effective group ID.
4400 mode has the setgid bit set.
4403 is a context dependent directory (only useful on HP-UX).
4417 owner is the shell's effective user ID.
4423 command above for a list of options).
4424 As a non-standard extension, if the option starts with a
4426 the test is negated; the test always fails if
4428 doesn't exist (so [ \-o foo \-o \-o !foo ] returns true if and only if option
4431 The same can be achieved with [ \-o ?foo ] like in
4435 can also be the short flag led by either
4439 .Pq no logical negation ,
4452 exists and is readable.
4456 .Xr unix 4 Ns -domain
4469 mode has the setuid bit set.
4472 exists and is writable.
4475 exists and is executable.
4476 .It Ar file1 Fl nt Ar file2
4485 .It Ar file1 Fl ot Ar file2
4494 .It Ar file1 Fl ef Ar file2
4500 has non-zero length.
4507 .It Ar string No = Ar string
4509 .It Ar string No == Ar string
4511 .It Ar string No \*(Gt Ar string
4512 First string operand is greater than second string operand.
4513 .It Ar string No \*(Lt Ar string
4514 First string operand is less than second string operand.
4515 .It Ar string No != Ar string
4516 Strings are not equal.
4517 .It Ar number Fl eq Ar number
4518 Numbers compare equal.
4519 .It Ar number Fl ne Ar number
4520 Numbers compare not equal.
4521 .It Ar number Fl ge Ar number
4522 Numbers compare greater than or equal.
4523 .It Ar number Fl gt Ar number
4524 Numbers compare greater than.
4525 .It Ar number Fl le Ar number
4526 Numbers compare less than or equal.
4527 .It Ar number Fl \< Ar number
4528 Numbers compare less than.
4531 The above basic expressions, in which unary operators have precedence over
4532 binary operators, may be combined with the following operators (listed in
4533 increasing order of precedence):
4534 .Bd -literal -offset indent
4535 expr \-o expr Logical OR.
4536 expr \-a expr Logical AND.
4541 Note that a number actually may be an arithmetic expression, such as
4542 a mathematical term or the name of an integer variable:
4543 .Bd -literal -offset indent
4544 x=1; [ "x" \-eq 1 ] evaluates to true
4547 Note that some special rules are applied (courtesy of
4549 ) if the number of arguments to
4551 or inside the brackets
4553 is less than five: if leading
4555 arguments can be stripped such that only one to three arguments remain,
4556 then the lowered comparison is executed; (thanks to XSI) parentheses
4558 lower four- and three-argument forms to two- and one-argument forms,
4559 respectively; three-argument forms ultimately prefer binary operations,
4560 followed by negation and parenthesis lowering; two- and four-argument forms
4561 prefer negation followed by parenthesis; the one-argument form always implies
4565 A common mistake is to use
4566 .Dq if \&[ $foo = bar \&]
4567 which fails if parameter
4571 or unset, if it has embedded spaces (i.e.\&
4573 octets), or if it is a unary operator like
4578 .Dq if \&[ x\&"$foo\&" = x"bar" \&]
4579 instead, or the double-bracket operator
4580 .Dq if \&[[ $foo = bar \&]]
4581 or, to avoid pattern matching (see
4584 .Dq if \&[[ $foo = \&"$bar" \&]]
4588 construct is not only more secure to use but also often faster.
4597 is given, the times used to execute the pipeline are reported.
4599 is given, then the user and system time used by the shell itself, and all the
4600 commands it has run since it was started, are reported.
4601 The times reported are the real time (elapsed time from start to finish),
4602 the user CPU time (time spent running in user mode), and the system CPU time
4603 (time spent running in kernel mode).
4604 Times are reported to standard error; the format of the output is:
4606 .Dl "0m0.00s real 0m0.00s user 0m0.00s system"
4610 option is given the output is slightly longer:
4611 .Bd -literal -offset indent
4617 It is an error to specify the
4621 is a simple command.
4623 Simple redirections of standard error do not affect the output of the
4627 .Dl $ time sleep 1 2\*(Gtafile
4628 .Dl $ { time sleep 1; } 2\*(Gtafile
4630 Times for the first command do not go to
4632 but those of the second command do.
4635 Print the accumulated user and system times used both by the shell
4636 and by processes that the shell started which have exited.
4637 The format of the output is:
4638 .Bd -literal -offset indent
4643 .It Ic trap Ar n Op Ar signal ...
4644 If the first operand is a decimal unsigned integer, this resets all
4645 specified signals to the default action, i.e. is the same as calling
4651 followed by the arguments
4652 .Pq Ar n Op Ar signal ... ,
4653 all of which are treated as signals.
4655 .It Ic trap Op Ar handler signal ...
4656 Sets a trap handler that is to be executed when any of the specified
4660 is either an empty string, indicating the signals are to be ignored,
4663 indicating that the default action is to be taken for the signals
4664 .Pq see Xr signal 3 ,
4665 or a string containing shell commands to be executed at the first opportunity
4666 (i.e. when the current command completes, or before printing the next
4668 prompt) after receipt of one of the signals.
4670 is the name of a signal
4671 .Pq e.g.\& Dv PIPE or Dv ALRM
4672 or the number of the signal (see the
4676 There are two special signals:
4678 .Pq also known as 0 ,
4679 which is executed when the shell is about to exit, and
4681 which is executed after an error occurs; an error is something
4682 that would cause the shell to exit if the
4685 .Ic set Fl o Ic errexit
4688 handlers are executed in the environment of the last executed command.
4690 Note that, for non-interactive shells, the trap handler cannot be changed
4691 for signals that were ignored when the shell started.
4693 With no arguments, the current state of the traps that have been set since
4694 the shell started is shown as a series of
4697 Note that the output of
4699 cannot be usefully piped to another process (an artifact of the fact that
4700 traps are cleared when subprocesses are created).
4702 The original Korn shell's
4704 trap and the handling of
4708 traps in functions are not yet implemented.
4711 A command that exits with a zero value.
4715 .Oo Op Ic +\-alpnrtUux
4720 .No \*(Ba Fl f Op Fl tux Oc
4722 .Op Ns = Ns Ar value
4727 .Oo Op Ic +\-alpnrtUux
4728 .Op Fl LRZ Ns Op Ar n
4730 .No \*(Ba Fl f Op Fl tux Oc
4732 .Op Ns = Ns Ar value
4735 Display or set parameter attributes.
4738 arguments, parameter attributes are displayed; if no options are used, the
4739 current attributes of all parameters are printed as
4741 commands; if an option is given (or
4743 with no option letter), all parameters and their values with the specified
4744 attributes are printed; if options are introduced with
4746 parameter values are not printed.
4750 arguments are given, the attributes of the named parameters are set
4754 Values for parameters may optionally be specified.
4757 the change affects the entire array, and no value may be specified.
4761 is used inside a function, any parameters specified are localised.
4762 This is not done by the otherwise identical
4769 equivalent to other programming languages' as it does not allow a
4770 function called from another function to access a parameter at truly
4771 global scope, but only prevents putting an accessed one into local scope.
4777 operates on the attributes of functions.
4778 As with parameters, if no
4780 arguments are given,
4781 functions are listed with their values (i.e. definitions) unless
4782 options are introduced with
4784 in which case only the function names are reported.
4787 Indexed array attribute.
4790 Display or set functions and their attributes, instead of parameters.
4794 specifies the base to use when displaying the integer (if not specified, the
4795 base given in the first assignment is used).
4796 Parameters with this attribute may
4797 be assigned values containing arithmetic expressions.
4799 Left justify attribute.
4801 specifies the field width.
4804 is not specified, the current width of a parameter (or the width of its first
4805 assigned value) is used.
4806 Leading whitespace (and zeros, if used with the
4808 option) is stripped.
4809 If necessary, values are either truncated or space padded
4810 to fit the field width.
4812 Lower case attribute.
4813 All upper case characters in values are converted to lower case.
4814 (In the original Korn shell, this parameter meant
4820 Create a bound variable (name reference): any access to the variable
4822 will access the variable
4824 in the current scope (this is different from
4833 is lazily evaluated at the time
4836 This can be used by functions to access variables whose names are
4837 passed as parametres, instead of using
4842 commands that can be used to re-create the attributes and values of
4845 Right justify attribute.
4847 specifies the field width.
4850 is not specified, the current width of a parameter (or the width of its first
4851 assigned value) is used.
4852 Trailing whitespace is stripped.
4853 If necessary, values are either stripped of leading characters or space
4854 padded to make them fit the field width.
4856 Read-only attribute.
4857 Parameters with this attribute may not be assigned to or unset.
4858 Once this attribute is set, it cannot be turned off.
4861 Has no meaning to the shell; provided for application use.
4865 is the trace attribute.
4866 When functions with the trace attribute are executed, the
4869 shell option is temporarily turned on.
4871 Unsigned integer attribute.
4872 Integers are printed as unsigned values (combine with the
4875 This option is not in the original Korn shell.
4877 Upper case attribute.
4878 All lower case characters in values are converted to upper case.
4879 (In the original Korn shell, this parameter meant
4880 .Dq unsigned integer
4883 option which meant upper case letters would never be used for bases greater
4891 is the undefined attribute.
4894 above for the implications of this.
4897 Parameters (or functions) are placed in the environment of
4898 any executed commands.
4899 Exported functions are not yet implemented.
4901 Zero fill attribute.
4902 If not combined with
4906 except zero padding is used instead of space padding.
4907 For integers, the number instead of the base is padded.
4920 options are changed, all others from this set are cleared,
4921 unless they are also given on the same command line.
4925 .Op Fl aBCcdefHilMmnOPpqrSsTtVvw
4928 Display or set process limits.
4929 If no options are used, the file size limit
4933 if specified, may be either an arithmetic expression or the word
4935 The limits affect the shell and any processes created by the shell after a
4937 Note that some systems may not allow limits to be increased
4939 Also note that the types of limits available are system
4940 dependent \*(en some systems have only the
4945 Display all limits; unless
4947 is used, soft limits are displayed.
4949 Set the socket buffer size to
4953 Set the number of cached threads to
4956 Impose a size limit of
4958 blocks on the size of core dumps.
4960 Impose a size limit of
4962 kibibytes on the size of the data area.
4964 Set the maximum niceness to
4967 Impose a size limit of
4969 blocks on files written by the shell and its child processes (files of any
4972 Set the hard limit only (the default is to set both hard and soft limits).
4974 Set the number of pending signals to
4979 kibibytes on the amount of locked (wired) physical memory.
4981 Set the AIO locked memory to
4987 kibibytes on the amount of physical memory used.
4991 file descriptors that can be open at once.
4993 Set the number of AIO operations to
4996 Limit the number of threads per process to
5001 processes that can be run by the user at any one time.
5009 Set the maximum real-time priority to
5012 Set the soft limit only (the default is to set both hard and soft limits).
5014 Impose a size limit of
5016 kibibytes on the size of the stack area.
5018 Impose a time limit of
5020 real seconds to be used by each process.
5022 Impose a time limit of
5024 CPU seconds spent in user mode to be used by each process.
5026 Set the number of vnode monitors on Haiku to
5031 kibibytes on the amount of virtual memory (address space) used.
5035 kibibytes on the amount of swap space used.
5040 is concerned, a block is 512 bytes.
5047 Display or set the file permission creation mask, or umask (see
5051 option is used, the mask displayed or set is symbolic; otherwise, it is an
5054 Symbolic masks are like those used by
5056 When used, they describe what permissions may be made available (as opposed to
5057 octal masks in which a set bit means the corresponding bit is to be cleared).
5060 sets the mask so files will not be readable, writable, or executable by
5062 and is equivalent (on most systems) to the octal mask
5070 The aliases for the given names are removed.
5073 option is used, all aliases are removed.
5078 options are used, the indicated operations are carried out on tracked or
5079 directory aliases, respectively.
5086 Unset the named parameters
5094 .Ar parameter Ns \&[*] ,
5095 attributes are kept, only values are unset.
5097 The exit status is non-zero if any of the parameters have the read-only
5098 attribute set, zero otherwise.
5100 .It Ic wait Op Ar job ...
5101 Wait for the specified job(s) to finish.
5104 is that of the last specified job; if the last job is killed by a signal, the
5105 exit status is 128 + the number of the signal (see
5106 .Ic kill Fl l Ar exit-status
5107 above); if the last specified job can't be found (because it never existed, or
5108 had already finished), the exit status of
5113 below for the format of
5116 will return if a signal for which a trap has been set is received, or if a
5123 If no jobs are specified,
5125 waits for all currently running jobs (if any) to finish and exits with a zero
5127 If job monitoring is enabled, the completion status of jobs is printed
5128 (this is not the case when jobs are explicitly specified).
5137 the type of command is listed (reserved word, built-in, alias,
5138 function, tracked alias, or executable).
5141 option is used, a path search is performed even if
5143 is a reserved word, alias, etc.
5152 will find reserved words and won't print aliases as alias commands.
5163 option does not affect the search path used, as it does for
5165 If the type of one or more of the names could not be determined, the exit
5169 Job control refers to the shell's ability to monitor and control jobs which
5170 are processes or groups of processes created for commands or pipelines.
5171 At a minimum, the shell keeps track of the status of the background (i.e.\&
5172 asynchronous) jobs that currently exist; this information can be displayed
5176 If job control is fully enabled (using
5179 .Ic set Fl o Ic monitor ) ,
5180 as it is for interactive shells, the processes of a job are placed in their
5182 Foreground jobs can be stopped by typing the suspend
5183 character from the terminal (normally \*(haZ), jobs can be restarted in either the
5184 foreground or background using the
5188 commands, and the state of the terminal is saved or restored when a foreground
5189 job is stopped or restarted, respectively.
5191 Note that only commands that create processes (e.g. asynchronous commands,
5192 subshell commands, and non-built-in, non-function commands) can be stopped;
5197 When a job is created, it is assigned a job number.
5198 For interactive shells, this number is printed inside
5200 followed by the process IDs of the processes in the job when an asynchronous
5202 A job may be referred to in the
5209 commands either by the process ID of the last process in the command pipeline
5212 parameter) or by prefixing the job number with a percent
5215 Other percent sequences can also be used to refer to jobs:
5216 .Bl -tag -width "%+ x %% x %XX"
5217 .It %+ \*(Ba %% \*(Ba %
5218 The most recently stopped job, or, if there are no stopped jobs, the oldest
5221 The job that would be the
5223 job if the latter did not exist.
5225 The job with job number
5228 The job with its command containing the string
5230 (an error occurs if multiple jobs are matched).
5232 The job with its command starting with the string
5234 (an error occurs if multiple jobs are matched).
5237 When a job changes state (e.g. a background job finishes or foreground job is
5238 stopped), the shell prints the following status information:
5240 .D1 [ Ns Ar number ] Ar flag status command
5243 .Bl -tag -width "command"
5245 is the job number of the job;
5251 character if the job is the
5255 job, respectively, or space if it is neither;
5257 indicates the current state of the job and can be:
5258 .Bl -tag -width "RunningXX"
5259 .It Done Op Ar number
5262 is the exit status of the job which is omitted if the status is zero.
5264 The job has neither stopped nor exited (note that running does not necessarily
5265 mean consuming CPU time \*(en
5266 the process could be blocked waiting for some event).
5267 .It Stopped Op Ar signal
5268 The job was stopped by the indicated
5270 (if no signal is given, the job was stopped by
5272 .It Ar signal-description Op Dq core dumped
5273 The job was killed by a signal (e.g. memory fault, hangup); use
5275 for a list of signal descriptions.
5278 message indicates the process created a core file.
5281 is the command that created the process.
5282 If there are multiple processes in
5283 the job, each process will have a line showing its
5287 if it is different from the status of the previous process.
5290 When an attempt is made to exit the shell while there are jobs in the stopped
5291 state, the shell warns the user that there are stopped jobs and does not exit.
5292 If another attempt is immediately made to exit the shell, the stopped jobs are
5295 signal and the shell exits.
5298 option is not set and there are running jobs when an attempt is made to exit
5299 a login shell, the shell warns the user and does not exit.
5301 is immediately made to exit the shell, the running jobs are sent a
5303 signal and the shell exits.
5304 .Ss Interactive input line editing
5305 The shell supports three modes of reading command lines from a
5307 in an interactive session, controlled by the
5312 options (at most one of these can be set at once).
5315 Editing modes can be set explicitly using the
5318 If none of these options are enabled,
5319 the shell simply reads lines using the normal
5326 option is set, the shell allows emacs-like editing of the command; similarly,
5329 option is set, the shell allows vi-like editing of the command.
5330 These modes are described in detail in the following sections.
5332 In these editing modes, if a line is longer than the screen width (see the
5340 character is displayed in the last column indicating that there are more
5341 characters after, before and after, or before the current position,
5343 The line is scrolled horizontally as necessary.
5345 Completed lines are pushed into the history, unless they begin with an
5346 IFS octet or IFS white space, or are the same as the previous line.
5347 .Ss Emacs editing mode
5350 option is set, interactive input line editing is enabled.
5351 Warning: This mode is
5352 slightly different from the emacs mode in the original Korn shell.
5353 In this mode, various editing commands
5354 (typically bound to one or more control characters) cause immediate actions
5355 without waiting for a newline.
5356 Several editing commands are bound to particular
5357 control characters when the shell is invoked; these bindings can be changed
5362 The following is a list of available editing commands.
5363 Each description starts with the name of the command,
5364 suffixed with a colon;
5367 (if the command can be prefixed with a count); and any keys the command is
5368 bound to by default, written using caret notation
5369 e.g. the ASCII ESC character is written as \*(ha[.
5370 These control sequences are not case sensitive.
5371 A count prefix for a command is entered using the sequence
5372 .Pf \*(ha[ Ns Ar n ,
5375 is a sequence of 1 or more digits.
5376 Unless otherwise specified, if a count is
5377 omitted, it defaults to 1.
5379 Note that editing command names are used only with the
5382 Furthermore, many editing commands are useful only on terminals with
5384 The default bindings were chosen to resemble corresponding
5391 reasonable substitutes and override the default bindings.
5393 .It abort: \*(haC, \*(haG
5394 Abort the current command, empty the line buffer and
5395 set the exit state to interrupted.
5396 .It auto\-insert: Op Ar n
5397 Simply causes the character to appear as literal input.
5398 Most ordinary characters are bound to this.
5399 .It Xo backward\-char:
5401 .No \*(haB , \*(haXD , ANSI-CurLeft , PC-CurLeft
5403 Moves the cursor backward
5406 .It Xo backward\-word:
5408 .No \*(ha[b , ANSI-Ctrl-CurLeft , ANSI-Alt-CurLeft
5410 Moves the cursor backward to the beginning of the word; words consist of
5411 alphanumerics, underscore
5416 .It beginning\-of\-history: \*(ha[\*(Lt
5417 Moves to the beginning of the history.
5418 .It beginning\-of\-line: \*(haA, ANSI-Home, PC-Home
5419 Moves the cursor to the beginning of the edited input line.
5420 .It Xo capitalise\-word:
5422 .No \*(ha[C , \*(ha[c
5424 Uppercase the first character in the next
5426 words, leaving the cursor past the end of the last word.
5427 .It clear\-screen: \*(ha[\*(haL
5428 Prints a compile-time configurable sequence to clear the screen and home
5429 the cursor, redraws the entire prompt and the currently edited input line.
5430 The default sequence works for almost all standard terminals.
5431 .It comment: \*(ha[#
5432 If the current line does not begin with a comment character, one is added at
5433 the beginning of the line and the line is entered (as if return had been
5434 pressed); otherwise, the existing comment characters are removed and the cursor
5435 is placed at the beginning of the line.
5436 .It complete: \*(ha[\*(ha[
5437 Automatically completes as much as is unique of the command name or the file
5438 name containing the cursor.
5439 If the entire remaining command or file name is
5440 unique, a space is printed after its completion, unless it is a directory name
5444 If there is no command or file name with the current partial word
5445 as its prefix, a bell character is output (usually causing a beep to be
5447 .It complete\-command: \*(haX\*(ha[
5448 Automatically completes as much as is unique of the command name having the
5449 partial word up to the cursor as its prefix, as in the
5452 .It complete\-file: \*(ha[\*(haX
5453 Automatically completes as much as is unique of the file name having the
5454 partial word up to the cursor as its prefix, as in the
5456 command described above.
5457 .It complete\-list: \*(haI, \*(ha[=
5458 Complete as much as is possible of the current word,
5459 and list the possible completions for it.
5460 If only one completion is possible,
5464 Note that \*(haI is usually generated by the TAB (tabulator) key.
5465 .It Xo delete\-char\-backward:
5467 .No ERASE , \*(ha? , \*(haH
5471 characters before the cursor.
5472 .It Xo delete\-char\-forward:
5474 .No ANSI-Del , PC-Del
5478 characters after the cursor.
5479 .It Xo delete\-word\-backward:
5481 .No WERASE , \*(ha[\*(ha? , \*(ha[\*(haH , \*(ha[h
5485 words before the cursor.
5486 .It Xo delete\-word\-forward:
5490 Deletes characters after the cursor up to the end of
5493 .It Xo down\-history:
5495 .No \*(haN , \*(haXB , ANSI-CurDown , PC-CurDown
5497 Scrolls the history buffer forward
5500 Each input line originally starts just after the last entry
5501 in the history buffer, so
5503 is not useful until either
5504 .Ic search\-history ,
5505 .Ic search\-history\-up
5509 .It Xo downcase\-word:
5511 .No \*(ha[L , \*(ha[l
5522 or the current line, if not specified, interactively.
5523 The actual command executed is
5524 .Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n .
5525 .It end\-of\-history: \*(ha[\*(Gt
5526 Moves to the end of the history.
5527 .It end\-of\-line: \*(haE, ANSI-End, PC-End
5528 Moves the cursor to the end of the input line.
5530 Acts as an end-of-file; this is useful because edit-mode input disables
5531 normal terminal input canonicalization.
5532 .It Xo eot\-or\-delete:
5538 if alone on a line; otherwise acts as
5539 .Ic delete\-char\-forward .
5540 .It error: (not bound)
5541 Error (ring the bell).
5542 .It exchange\-point\-and\-mark: \*(haX\*(haX
5543 Places the cursor where the mark is and sets the mark to where the cursor was.
5544 .It expand\-file: \*(ha[*
5547 to the current word and replaces the word with the result of performing file
5548 globbing on the word.
5549 If no files match the pattern, the bell is rung.
5550 .It Xo forward\-char:
5552 .No \*(haF , \*(haXC , ANSI-CurRight , PC-CurRight
5554 Moves the cursor forward
5557 .It Xo forward\-word:
5559 .No \*(ha[f , ANSI-Ctrl-CurRight , ANSI-Alt-CurRight
5561 Moves the cursor forward to the end of the
5564 .It Xo goto\-history:
5568 Goes to history number
5570 .It kill\-line: KILL
5571 Deletes the entire input line.
5572 .It kill\-region: \*(haW
5573 Deletes the input between the cursor and the mark.
5574 .It Xo kill\-to\-eol:
5578 Deletes the input from the cursor to the end of the line if
5580 is not specified; otherwise deletes characters between the cursor and column
5583 Prints a sorted, columnated list of command names or file names (if any) that
5584 can complete the partial word containing the cursor.
5585 Directory names have
5588 .It list\-command: \*(haX?
5589 Prints a sorted, columnated list of command names (if any) that can complete
5590 the partial word containing the cursor.
5591 .It list\-file: \*(haX\*(haY
5592 Prints a sorted, columnated list of file names (if any) that can complete the
5593 partial word containing the cursor.
5594 File type indicators are appended as described under
5597 .It newline: \*(haJ , \*(haM
5598 Causes the current input line to be processed by the shell.
5599 The current cursor position may be anywhere on the line.
5600 .It newline\-and\-next: \*(haO
5601 Causes the current input line to be processed by the shell, and the next line
5602 from history becomes the current line.
5603 This is only useful after an
5607 .Ic search\-history\-up .
5610 .It prefix\-1: \*(ha[
5611 Introduces a 2-character command sequence.
5612 .It prefix\-2: \*(haX , \*(ha[[ , \*(ha[O
5613 Introduces a 2-character command sequence.
5614 .It Xo prev\-hist\-word:
5616 .No \*(ha[. , \*(ha[_
5618 The last word, or, if given, the
5620 word (zero-based) of the previous (on repeated execution, second-last,
5621 third-last, etc.) command is inserted at the cursor.
5622 Use of this editing command trashes the mark.
5623 .It quote: \*(ha\*(ha , \*(haV
5624 The following character is taken literally rather than as an editing command.
5626 Reprints the last line of the prompt string and the current input line
5628 .It Xo search\-character\-backward:
5632 Search backward in the current line for the
5634 occurrence of the next character typed.
5635 .It Xo search\-character\-forward:
5639 Search forward in the current line for the
5641 occurrence of the next character typed.
5642 .It search\-history: \*(haR
5643 Enter incremental search mode.
5644 The internal history list is searched
5645 backwards for commands matching the input.
5648 in the search string anchors the search.
5649 The escape key will leave search mode.
5650 Other commands, including sequences of escape as
5656 key will be executed after leaving search mode.
5659 command will restore the input line before search started.
5662 commands continue searching backward to the next previous occurrence of the
5664 The history buffer retains only a finite number of lines; the oldest
5665 are discarded as necessary.
5666 .It search\-history\-up: ANSI-PgUp, PC-PgUp
5667 Search backwards through the history buffer for commands whose beginning match
5668 the portion of the input line before the cursor.
5669 When used on an empty line, this has the same effect as
5671 .It search\-history\-down: ANSI-PgDn, PC-PgDn
5672 Search forwards through the history buffer for commands whose beginning match
5673 the portion of the input line before the cursor.
5674 When used on an empty line, this has the same effect as
5676 This is only useful after an
5680 .Ic search\-history\-up .
5681 .It set\-mark\-command: \*(ha[ Ns Aq space
5682 Set the mark at the cursor position.
5683 .It transpose\-chars: \*(haT
5684 If at the end of line, or if the
5686 option is set, this exchanges the two previous characters; otherwise, it
5687 exchanges the previous and current characters and moves the cursor one
5688 character to the right.
5691 .No \*(haP , \*(haXA , ANSI-CurUp , PC-CurUp
5693 Scrolls the history buffer backward
5696 .It Xo upcase\-word:
5698 .No \*(ha[U , \*(ha[u
5703 .It version: \*(ha[\*(haV
5704 Display the version of
5706 The current edit buffer is restored as soon as a key is pressed.
5707 The restoring keypress is processed, unless it is a space.
5709 Inserts the most recently killed text string at the current cursor position.
5710 .It yank\-pop: \*(ha[y
5713 replaces the inserted text string with the next previously killed text string.
5717 The vi command-line editing mode is orphaned, yet still functional.
5718 It is 8-bit clean but specifically does not support UTF-8 or MBCS.
5720 The vi command-line editor in
5722 has basically the same commands as the
5724 editor with the following exceptions:
5727 You start out in insert mode.
5729 There are file name and command completion commands:
5730 =, \e, *, \*(haX, \*(haE, \*(haF, and, optionally,
5737 command is different (in
5739 it is the last argument command; in
5741 it goes to the start of the current line).
5747 commands move in the opposite direction to the
5751 Commands which don't make sense in a single line editor are not available
5752 (e.g. screen movement commands and
5761 there are two modes:
5766 In insert mode, most characters are simply put in the buffer at the
5767 current cursor position as they are typed; however, some characters are
5769 In particular, the following characters are taken from current
5774 and have their usual meaning (normal values are in parentheses): kill (\*(haU),
5775 erase (\*(ha?), werase (\*(haW), eof (\*(haD), intr (\*(haC), and quit (\*(ha\e).
5777 the above, the following characters are also treated specially in insert mode:
5778 .Bl -tag -width XJXXXXM
5780 Command and file name enumeration (see below).
5782 Command and file name completion (see below).
5783 If used twice in a row, the
5784 list of possible completions is displayed; if used a third time, the completion
5787 Erases previous character.
5788 .It \*(haJ \*(Ba \*(haM
5790 The current line is read, parsed, and executed by the shell.
5793 The next character typed is not treated specially (can be used
5794 to insert the characters being described here).
5796 Command and file name expansion (see below).
5798 Puts the editor in command mode (see below).
5800 Optional file name and command completion (see
5802 above), enabled with
5803 .Ic set Fl o Ic vi\-tabcomplete .
5806 In command mode, each character is interpreted as a command.
5808 don't correspond to commands, are illegal combinations of commands, or are
5809 commands that can't be carried out, all cause beeps.
5810 In the following command descriptions, an
5812 indicates the command may be prefixed by a number (e.g.\&
5814 moves right 10 characters); if no number prefix is used,
5816 is assumed to be 1 unless otherwise specified.
5818 .Dq current position
5819 refers to the position between the cursor and the character preceding the
5823 is a sequence of letters, digits, and underscore characters or a sequence of
5824 non-letter, non-digit, non-underscore, and non-whitespace characters (e.g.\&
5826 contains two words) and a
5828 is a sequence of non-whitespace characters.
5834 The following commands are not in, or are different from, the normal vi file
5840 Insert a space followed by the
5842 big-word from the last command in the history at the current position and enter
5845 is not specified, the last word is inserted.
5847 Insert the comment character
5849 at the start of the current line and return the line to the shell (equivalent
5859 is not specified, it goes to the most recent remembered line.
5869 is not specified, the current line is edited.
5870 The actual command executed is
5871 .Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n .
5873 Command or file name expansion is applied to the current big-word (with an
5876 if the word contains no file globbing characters) \*(en the big-word is replaced
5877 with the resulting words.
5878 If the current big-word is the first on the line
5879 or follows one of the characters
5886 and does not contain a slash
5888 then command expansion is done; otherwise file name expansion is done.
5889 Command expansion will match the big-word against all aliases, functions, and
5890 built-in commands as well as any executable files found by searching the
5894 File name expansion matches the big-word against the files in the
5896 After expansion, the cursor is placed just past the last
5897 word and the editor is in insert mode.
5900 .Oo Ar n Oc Ns \*(haF ,
5901 .Oo Ar n Oc Ns Aq tab ,
5903 .Oo Ar n Oc Ns Aq esc
5905 Command/file name completion.
5906 Replace the current big-word with the
5907 longest unique match obtained after performing command and file name expansion.
5909 is only recognised if the
5911 option is set, while
5913 is only recognised if the
5921 possible completion is selected (as reported by the command/file name
5922 enumeration command).
5924 Command/file name enumeration.
5925 List all the commands or files that match the current big-word.
5927 Display the version of
5929 The current edit buffer is restored as soon as a key is pressed.
5930 The restoring keypress is ignored.
5933 Execute the commands found in the alias
5937 Intra-line movement commands:
5940 .Oo Ar n Oc Ns h and
5941 .Oo Ar n Oc Ns \*(haH
5947 .Oo Ar n Oc Ns l and
5948 .Oo Ar n Oc Ns Aq space
5956 Move to the first non-whitespace character.
5958 .Oo Ar n Oc Ns \*(Ba
5963 Move to the last character.
5979 Move forward to the end of the word,
5985 Move forward to the end of the big-word,
6002 The editor looks forward for the nearest parenthesis, bracket, or
6003 brace and then moves the cursor to the matching parenthesis, bracket, or brace.
6005 .Oo Ar n Oc Ns f Ns Ar c
6009 occurrence of the character
6012 .Oo Ar n Oc Ns F Ns Ar c
6014 Move backward to the
6016 occurrence of the character
6019 .Oo Ar n Oc Ns t Ns Ar c
6021 Move forward to just before the
6023 occurrence of the character
6026 .Oo Ar n Oc Ns T Ns Ar c
6028 Move backward to just before the
6030 occurrence of the character
6047 command, but moves in the opposite direction.
6050 Inter-line movement commands:
6056 .Oo Ar n Oc Ns \*(haN
6060 next line in the history.
6065 .Oo Ar n Oc Ns \*(haP
6069 previous line in the history.
6077 is not specified, the number of the first remembered line is used.
6085 is not specified, it goes to the most recent remembered line.
6087 .Oo Ar n Oc Ns / Ns Ar string
6089 Search backward through the history for the
6097 the remainder of the string must appear at the start of the history line for
6100 .Oo Ar n Oc Ns \&? Ns Ar string
6104 except it searches forward through the history.
6110 occurrence of the last search string;
6111 the direction of the search is the same as the last search.
6117 occurrence of the last search string;
6118 the direction of the search is the opposite of the last search.
6119 .It Ar ANSI-CurUp , PC-PgUp
6120 Take the characters from the beginning of the line to the current
6121 cursor position as search string and do a backwards history search
6122 for lines beginning with this string; keep the cursor position.
6123 This works only in insert mode and keeps it enabled.
6133 times; goes into insert mode just after the current position.
6135 only replicated if command mode is re-entered i.e.\&
6143 except it appends at the end of the line.
6149 times; goes into insert mode at the current position.
6150 The insertion is only
6151 replicated if command mode is re-entered i.e.\&
6159 except the insertion is done just before the first non-blank character.
6165 characters (i.e. delete the characters and go into insert mode).
6167 Substitute whole line.
6168 All characters from the first non-blank character to the
6169 end of the line are deleted and insert mode is entered.
6171 .Oo Ar n Oc Ns c Ns Ar move-cmd
6173 Change from the current position to the position resulting from
6175 (i.e. delete the indicated region and go into insert mode); if
6179 the line starting from the first non-blank character is changed.
6181 Change from the current position to the end of the line (i.e. delete to the
6182 end of the line and go into insert mode).
6196 Delete to the end of the line.
6198 .Oo Ar n Oc Ns d Ns Ar move-cmd
6200 Delete from the current position to the position resulting from
6201 .Ar n move-cmd Ns s ;
6203 is a movement command (see above) or
6205 in which case the current line is deleted.
6207 .Oo Ar n Oc Ns r Ns Ar c
6211 characters with the character
6217 Enter insert mode but overwrite existing characters instead of
6218 inserting before existing characters.
6219 The replacement is repeated
6223 .Oo Ar n Oc Ns \*(TI
6225 Change the case of the next
6229 .Oo Ar n Oc Ns y Ns Ar move-cmd
6231 Yank from the current position to the position resulting from
6233 into the yank buffer; if
6237 the whole line is yanked.
6239 Yank from the current position to the end of the line.
6243 Paste the contents of the yank buffer just after the current position,
6251 except the buffer is pasted at the current position.
6254 Miscellaneous vi commands
6256 .It \*(haJ and \*(haM
6257 The current line is read, parsed, and executed by the shell.
6258 .It \*(haL and \*(haR
6259 Redraw the current line.
6263 Redo the last edit command
6267 Undo the last edit command.
6269 Undo all changes that have been made to the current line.
6270 .It PC Home, End, Del, and cursor keys
6271 They move as expected, both in insert and command mode.
6272 .It Ar intr No and Ar quit
6273 The interrupt and quit terminal characters cause the current line to be
6274 deleted and a new prompt to be printed.
6277 .Bl -tag -width XetcXsuid_profile -compact
6278 .It Pa \*(TI/.mkshrc
6279 User mkshrc profile (non-privileged interactive shells); see
6281 The location can be changed at compile time (for embedded systems);
6282 AOSP Android builds use
6283 .Pa /system/etc/mkshrc .
6284 .It Pa \*(TI/.profile
6285 User profile (non-privileged login shells); see
6287 near the top of this manual.
6289 System profile (login shells); see
6293 .It Pa /etc/suid_profile
6294 Suid profile (privileged shells); see
6300 contains the system and suid profile.
6331 .Pa http://docsrv.sco.com:507/en/man/html.C/sh.C.html
6333 .Pa https://www.mirbsd.org/ksh\-chan.htm
6336 .%B "The KornShell Command and Programming Language"
6338 .%I "Prentice Hall PTR"
6339 .%P "xvi\ +\ 356 pages"
6340 .%O "ISBN 978\-0\-13\-516972\-8 (0\-13\-516972\-0)"
6343 .%A Morris I. Bolsky
6345 .%B "The New KornShell Command and Programming Language (2nd Edition)"
6347 .%I "Prentice Hall PTR"
6348 .%P "xvi\ +\ 400 pages"
6349 .%O "ISBN 978\-0\-13\-182700\-4 (0\-13\-182700\-6)"
6352 .%A Stephen G. Kochan
6354 .%B "\\*(tNUNIX\\*(sP Shell Programming"
6358 .%P "xiii\ +\ 437 pages"
6359 .%O "ISBN 978\-0\-672\-32490\-1 (0\-672\-32490\-3)"
6363 .%T "\\*(tNIEEE\\*(sP Standard for Information Technology \*(en Portable Operating System Interface (POSIX)"
6364 .%V "Part 2: Shell and Utilities"
6367 .%P "xvii\ +\ 1195 pages"
6368 .%O "ISBN 978\-1\-55937\-255\-8 (1\-55937\-255\-9)"
6372 .%B "Learning the Korn Shell"
6376 .%O "ISBN 978\-1\-56592\-054\-5 (1\-56592\-054\-6)"
6381 .%B "Learning the Korn Shell, Second Edition"
6385 .%O "ISBN 978\-0\-596\-00195\-7 (0\-596\-00195\-9)"
6389 .%B "KornShell Programming Tutorial"
6391 .%I "Addison-Wesley Professional"
6392 .%P "xxi\ +\ 324 pages"
6393 .%O "ISBN 978\-0\-201\-56324\-5 (0\-201\-56324\-X)"
6397 .Nm "The MirBSD Korn Shell"
6399 .An Thorsten Glaser Aq tg@mirbsd.org
6400 and currently maintained as part of The MirOS Project.
6401 This shell is based on the public domain 7th edition Bourne shell clone by
6402 .An Charles Forsyth ,
6403 who kindly agreed to, in countries where the Public Domain status of the work
6404 may not be valid, grant a copyright licence to the general public to deal in
6405 the work without restriction and permission to sublicence derivates under the
6406 terms of any (OSI approved) Open Source licence,
6407 and parts of the BRL shell by
6411 .An Arnold Robbins ,
6414 The first release of
6418 and it was subsequently maintained by
6419 .An John R. MacMillan Aq Mt change!john@sq.sq.com ,
6420 .An Simon J. Gerraty Aq Mt sjg@zen.void.oz.au ,
6422 .An Michael Rendell Aq Mt michael@cs.mun.ca .
6423 The effort of several projects, such as Debian and OpenBSD, and other
6424 contributors including our users, to improve the shell is appreciated.
6425 See the documentation, CVS, and web site for details.
6427 The BSD daemon is Copyright \(co Marshall Kirk McKusick.
6428 The complete legalese is at:
6429 .Pa https://www.mirbsd.org/TaC\-mksh.txt
6431 .\" This boils down to: feel free to use mksh.ico as application icon
6432 .\" or shortcut for mksh or mksh/Win32; distro patches are ok (but we
6433 .\" request they amend $KSH_VERSION when modifying mksh). Authors are
6434 .\" Marshall Kirk McKusick (UCB), Rick Collette (ekkoBSD), Thorsten
6435 .\" Glaser, Benny Siegert (MirBSD), Michael Langguth (mksh/Win32).
6437 .\" As far as MirBSD is concerned, the files themselves are free
6438 .\" to modification and distribution under BSD/MirOS Licence, the
6439 .\" restriction on use stems only from trademark law's requirement
6440 .\" to protect it or lose it, which McKusick almost did.
6444 has a different scope model from
6447 which leads to subtile differences in semantics for identical builtins.
6448 This can cause issues with a
6450 to suddenly point to a local variable by accident; fixing this is hard.
6452 The parts of a pipeline, like below, are executed in subshells.
6453 Thus, variable assignments inside them are not visible in the
6454 surrounding execution environment.
6455 Use co-processes instead.
6456 .Bd -literal -offset indent
6457 foo \*(Ba bar \*(Ba read baz # will not change $baz
6458 foo \*(Ba bar \*(Ba& read \-p baz # will, however, do so
6462 provides a consistent set of 32-bit integer arithmetics, both signed
6463 and unsigned, with defined wraparound and sign of the result of a
6464 remainder operation, even (defying POSIX) on 64-bit systems.
6465 If you require 64-bit integer arithmetics, use
6466 .Nm lksh Pq legacy mksh
6467 instead, but be aware that, in POSIX, it's legal for the OS to make
6468 .Li print $((2147483647 + 1))
6469 delete all files on your system, as it's Undefined Behaviour.
6472 provides a consistent, clear interface normally.
6473 This may deviate from POSIX in optional or opinionated places, such
6474 as whether leading-digit-zero numbers should be interpreted as octal.
6475 .Ic set Fl o Ic posix
6476 will cause the shell (either
6480 to behave more like the standard expects.
6490 only supports the Unicode BMP (Basic Multilingual Plane) and maps
6491 raw octets into the U+EF80..U+EFFF wide character range; compare
6492 .Sx Arithmetic expressions .
6498 option dependent on the current
6500 locale for mksh to allow using the UTF-8 mode, within the constraints
6501 outlined above, in code portable across various shell implementations:
6502 .Bd -literal -offset indent
6503 case ${KSH_VERSION:\-} in
6504 *MIRBSD\ KSH*\*(Ba*LEGACY\ KSH*)
6505 case ${LC_ALL:\-${LC_CTYPE:\-${LANG:\-}}} in
6506 *[Uu][Tt][Ff]8*\*(Ba*[Uu][Tt][Ff]\-8*) set \-U ;;
6512 Suspending (using \*(haZ) pipelines like the one below will only suspend
6513 the currently running part of the pipeline; in this example,
6515 is immediately printed on suspension (but not later after an
6517 .Bd -literal -offset indent
6518 $ /bin/sleep 666 && echo fubar
6521 The truncation process involved when changing
6523 does not free old history entries (leaks memory) and leaks
6524 old entries into the new history if their line numbers are
6525 not overwritten by same-numer entries from the persistent
6526 history file; truncating the on-disc file to
6528 lines has always been broken and prone to history file corruption
6529 when multiple shells are accessing the file; the rollover process
6530 for the in-memory portion of the history is slow, should use
6533 This document attempts to describe
6536 .\" with vendor patches from insert-your-name-here,
6537 compiled without any options impacting functionality, such as
6541 which, on some systems only, enables
6542 .Ic set Fl o Ic posix
6545 automatically (whose behaviour differs across targets),
6546 for an operating environment supporting all of its advanced needs.
6548 Please report bugs in
6553 .Aq miros\-mksh@mirbsd.org
6558 .Pa irc.freenode.net
6559 .Pq Port 6697 SSL, 6667 unencrypted ,
6561 .Pa https://launchpad.net/mksh
OSDN Git Service
