1 .\" $MirOS: src/bin/mksh/mksh.1,v 1.320 2013/08/10 14:11:39 tg Exp $
2 .\" $OpenBSD: ksh.1,v 1.147 2013/06/13 19:43:09 millert Exp $
4 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
5 .\" 2010, 2011, 2012, 2013
6 .\" Thorsten 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: August 10 2013 $
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
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 this option is used
251 or if the real user ID or group ID does not match the
252 effective user ID or group ID (see
256 Clearing the privileged option causes the shell to set
257 its effective user ID (group ID) to its real user ID (group ID).
258 For further implications, see
266 The following restrictions come into effect after the shell processes any
283 parameters cannot be changed.
285 Command names can't be specified with absolute or relative paths.
289 option of the built-in command
293 Redirections that create files can't be used (i.e.\&
300 The shell reads commands from standard input; all non-option arguments
301 are positional parameters.
310 .Pa /dev/ttyC Ns Ar name
312 .Pa /dev/tty Ns Ar name
313 are attempted in order.
316 begins with an exclamation mark
318 this is done in a subshell and returns immediately.
323 detach from controlling terminal (daemonise) instead.
326 In addition to the above, the options described in the
328 built-in command can also be used on the command line:
330 .Op Fl +abCefhkmnuvXx
333 can be used for single letter or long options, respectively.
339 option is specified, the first non-option argument specifies the name
340 of a file the shell reads commands from.
341 If there are no non-option
342 arguments, the shell reads commands from the standard input.
343 The name of the shell (i.e. the contents of $0)
344 is determined as follows: if the
346 option is used and there is a non-option argument, it is used as the name;
347 if commands are being read from a file, the file is used as the name;
348 otherwise, the basename the shell was called with (i.e. argv[0]) is used.
350 The exit status of the shell is 127 if the command file specified on the
351 command line could not be opened, or non-zero if a fatal syntax error
352 occurred during the execution of a script.
353 In the absence of fatal errors,
354 the exit status is that of the last command executed, or zero, if no
357 For the actual location of these files, see
359 A login shell processes the system profile first.
360 A privileged shell then processes the suid profile.
361 A non-privileged login shell processes the user profile next.
362 A non-privileged interactive shell checks the value of the
364 parameter after subjecting it to parameter, command, arithmetic and tilde
366 substitution; if unset or empty, the user mkshrc profile is processed;
367 otherwise, if a file whose name is the substitution result exists,
368 it is processed; non-existence is silently ignored.
370 The shell begins parsing its input by removing any backslash-newline
371 combinations, then breaking it into
373 Words (which are sequences of characters) are delimited by unquoted whitespace
374 characters (space, tab, and newline) or meta-characters
385 Aside from delimiting words, spaces and tabs are ignored, while newlines
386 usually delimit commands.
387 The meta-characters are used in building the following
392 .Ql \*(Lt\*(Lt\*(Lt ,
397 etc. are used to specify redirections (see
398 .Sx Input/output redirection
401 is used to create pipelines;
403 is used to create co-processes (see
407 is used to separate commands;
409 is used to create asynchronous pipelines;
413 are used to specify conditional execution;
422 is used in arithmetic expressions;
425 is used to create subshells.
427 Whitespace and meta-characters can be quoted individually using a backslash
429 or in groups using double
434 Note that the following characters are also treated specially by the
435 shell and must be quoted if they are to represent themselves:
449 The first three of these are the above mentioned quoting characters (see
453 if used at the beginning of a word, introduces a comment \*(en everything after
456 up to the nearest newline is ignored;
458 is used to introduce parameter, command, and arithmetic substitutions (see
462 introduces an old-style command substitution (see
466 begins a directory expansion (see
482 are used in file name generation (see
483 .Sx File name patterns
486 As words and tokens are parsed, the shell builds commands, of which there
488 .Em simple-commands ,
489 typically programmes that are executed, and
490 .Em compound-commands ,
495 statements, grouping constructs, and function definitions.
497 A simple-command consists of some combination of parameter assignments
501 input/output redirections (see
502 .Sx Input/output redirections
504 and command words; the only restriction is that parameter assignments come
505 before any command words.
506 The command words, if any, define the command
507 that is to be executed and its arguments.
508 The command may be a shell built-in command, a function,
509 or an external command
510 (i.e. a separate executable file that is located using the
513 .Sx Command execution
515 Note that all command constructs have an exit status: for external commands,
516 this is related to the status returned by
518 (if the command could not be found, the exit status is 127; if it could not
519 be executed, the exit status is 126); the exit status of other command
520 constructs (built-in commands, functions, compound-commands, pipelines, lists,
521 etc.) are all well-defined and are described where the construct is
523 The exit status of a command consisting only of parameter
524 assignments is that of the last command substitution performed during the
525 parameter assignment or 0 if there were no command substitutions.
527 Commands can be chained together using the
529 token to form pipelines, in which the standard output of each command but the
532 to the standard input of the following command.
533 The exit status of a pipeline is that of its last command, unless the
535 option is set (see there).
536 All commands of a pipeline are executed in separate subshells;
537 this is allowed by POSIX but differs from both variants of
540 where all but the last command were executed in subshells; see the
542 builtin's description for implications and workarounds.
543 A pipeline may be prefixed by the
545 reserved word which causes the exit status of the pipeline to be logically
546 complemented: if the original status was 0, the complemented status will be 1;
547 if the original status was not 0, the complemented status will be 0.
550 of commands can be created by separating pipelines by any of the following
558 The first two are for conditional execution:
559 .Dq Ar cmd1 No && Ar cmd2
562 only if the exit status of
566 is the opposite \*(en
568 is executed only if the exit status of
574 have equal precedence which is higher than that of
579 which also have equal precedence.
585 .Qq left-associative .
586 For example, both of these commands will print only
588 .Bd -literal -offset indent
589 $ false && echo foo \*(Ba\*(Ba echo bar
590 $ true \*(Ba\*(Ba echo foo && echo bar
595 token causes the preceding command to be executed asynchronously; that is,
596 the shell starts the command but does not wait for it to complete (the shell
597 does keep track of the status of asynchronous commands; see
600 When an asynchronous command is started when job control is disabled
601 (i.e. in most scripts), the command is started with signals
605 ignored and with input redirected from
607 (however, redirections specified in the asynchronous command have precedence).
610 operator starts a co-process which is a special kind of asynchronous process
614 Note that a command must follow the
618 operators, while it need not follow
623 The exit status of a list is that of the last command executed, with the
624 exception of asynchronous lists, for which the exit status is 0.
626 Compound commands are created using the following reserved words.
628 are only recognised if they are unquoted and if they are used as the first
629 word of a command (i.e. they can't be preceded by parameter assignments or
631 .Bd -literal -offset indent
632 case else function then ! (
633 do esac if time [[ ((
635 elif for select while }
638 In the following compound command descriptions, command lists (denoted as
640 that are followed by reserved words must end with a semicolon, a newline, or
641 a (syntactically correct) reserved word.
642 For example, the following are all valid:
643 .Bd -literal -offset indent
644 $ { echo foo; echo bar; }
645 $ { echo foo; echo bar\*(Ltnewline\*(Gt}
646 $ { { echo foo; echo bar; } }
651 .Dl $ { echo foo; echo bar }
657 There is no implicit way to pass environment changes from a
658 subshell back to its parent.
662 is executed, but not in a subshell.
667 are reserved words, not meta-characters.
668 .It Xo case Ar word No in
674 .Op ;; \*(Ba ;&\& \*(Ba ;\*(Ba\ \&
679 statement attempts to match
685 associated with the first successfully matched pattern is executed.
688 statements are the same as those used for file name patterns except that the
689 restrictions regarding
694 Note that any unquoted space before and after a pattern is
695 stripped; any space within a pattern must be quoted.
696 Both the word and the
697 patterns are subject to parameter, command, and arithmetic substitution, as
698 well as tilde substitution.
700 For historical reasons, open and close braces may be used instead of
705 .Ic case $foo { *) echo bar;; } .
707 The list terminators are:
710 Terminate after the list.
712 Fall through into the next list.
714 Evaluate the remaining pattern-list tuples.
719 statement is that of the executed
723 is executed, the exit status is zero.
725 .Oo in Ar word No ... Oc ;
726 .No do Ar list ; No done
730 in the specified word list, the parameter
732 is set to the word and
737 is not used to specify a word list, the positional parameters
740 For historical reasons, open and close braces may be used instead of
745 .Ic for i; { echo $i; } .
748 statement is the last exit status of
752 is never executed, the exit status is zero.
756 .No then Ar list ; Oc
758 .Oo else Ar list ; Oc
761 If the exit status of the first
765 is executed; otherwise, the
769 if any, is executed with similar consequences.
770 If all the lists following the
774 fail (i.e. exit with non-zero status), the
779 The exit status of an
781 statement is that of non-conditional
783 that is executed; if no non-conditional
785 is executed, the exit status is zero.
786 .It Xo select Ar name
787 .Oo in Ar word No ... Oc ;
788 .No do Ar list ; No done
792 statement provides an automatic method of presenting the user with a menu and
794 An enumerated list of the specified
796 is printed on standard error, followed by a prompt
801 A number corresponding to one of the enumerated words is then read from
804 is set to the selected word (or unset if the selection is not valid),
806 is set to what was read (leading/trailing space is stripped), and
809 If a blank line (i.e. zero or more
811 octets) is entered, the menu is reprinted without executing
816 completes, the enumerated list is printed if
820 the prompt is printed, and so on.
821 This process continues until an end-of-file
822 is read, an interrupt is received, or a
824 statement is executed inside the loop.
827 is omitted, the positional parameters are used
829 For historical reasons, open and close braces may be used instead of
834 .Ic select i; { echo $i; } .
837 statement is zero if a
839 statement is used to exit the loop, non-zero otherwise.
840 .It Xo until Ar list ;
846 except that the body is executed only while the exit status of the first
849 .It Xo while Ar list ;
855 is a pre-checked loop.
856 Its body is executed as often as the exit status of the first
861 statement is the last exit status of the
863 in the body of the loop; if the body is not executed, the exit status is zero.
864 .It Xo function Ar name
872 Note that redirections specified after a function definition are
873 performed whenever the function is executed, not when the function definition
875 .It Ar name Ns \&() Ar command
881 Whitespace (space or tab) after
883 will be ignored most of the time.
884 .It Xo function Ar name Ns \&()
893 .It Xo Ic time Op Fl p
897 .Sx Command execution
898 section describes the
901 .It \&(( Ar expression No ))
902 The arithmetic expression
904 is evaluated; equivalent to
907 .Sx Arithmetic expressions
911 .It Bq Bq Ar \ \&expression\ \&
916 commands (described later), with the following exceptions:
919 Field splitting and file name generation are not performed on arguments.
927 operators are replaced with
939 Parameter, command, and arithmetic substitutions are performed as expressions
940 are evaluated and lazy expression evaluation is used for the
945 This means that in the following statement,
947 is evaluated if and only if the file
949 exists and is readable:
950 .Bd -literal -offset indent
951 $ [[ \-r foo && $(\*(Ltfoo) = b*r ]]
954 The second operand of the
958 expressions are patterns (e.g. the comparison
959 .Ic \&[[ foobar = f*r ]]
961 This even works indirectly:
962 .Bd -literal -offset indent
963 $ bar=foobar; baz=\*(aqf*r\*(aq
964 $ [[ $bar = $baz ]]; echo $?
965 $ [[ $bar = \&"$baz" ]]; echo $?
968 Perhaps surprisingly, the first comparison succeeds,
969 whereas the second doesn't.
973 Quoting is used to prevent the shell from treating characters or words
975 There are three methods of quoting.
978 quotes the following character, unless it is at the end of a line, in which
981 and the newline are stripped.
982 Second, a single quote
984 quotes everything up to the next single quote (this may span lines).
985 Third, a double quote
987 quotes all characters, except
992 up to the next unquoted double quote.
996 inside double quotes have their usual meaning (i.e. parameter, command, or
997 arithmetic substitution) except no field splitting is carried out on the
998 results of double-quoted substitutions.
1001 inside a double-quoted string is followed by
1007 it is replaced by the second character; if it is followed by a newline, both
1010 and the newline are stripped; otherwise, both the
1012 and the character following are unchanged.
1014 If a single-quoted string is preceded by an unquoted
1016 C style backslash expansion (see below) is applied (even single quote
1017 characters inside can be escaped and do not terminate the string then);
1018 the expanded result is treated as any other single-quoted string.
1019 If a double-quoted string is preceded by an unquoted
1021 the latter is ignored.
1022 .Ss Backslash expansion
1023 In places where backslashes are expanded, certain C and
1028 style escapes are translated.
1045 means a hexadecimal digit, of thich there may be none up to four or eight;
1046 these escapes translate a Unicode codepoint to UTF-8.
1051 expand to the escape character.
1060 are explicitly excluded;
1061 octal sequences must have the none up to three octal digits
1063 prefixed with the digit zero
1065 hexadecimal sequences
1067 are limited to none up to two hexadecimal digits
1069 both octal and hexadecimal sequences convert to raw octets;
1071 where # is none of the above, translates to \e# (backslashes are retained).
1073 Backslash expansion in the C style mode slightly differs: octal sequences
1075 must have no digit zero prefixing the one up to three octal digits
1077 and yield raw octets; hexadecimal sequences
1079 greedily eat up as many hexadecimal digits
1081 as they can and terminate with the first non-hexadecimal digit;
1082 these translate a Unicode codepoint to UTF-8.
1087 is any octet, translates to Ctrl-# (which basically means,
1089 becomes DEL, everything else is bitwise ANDed with 0x1F).
1092 where # is none of the above, translates to # (has the backslash trimmed),
1093 even if it is a newline.
1095 There are two types of aliases: normal command aliases and tracked aliases.
1096 Command aliases are normally used as a short hand for a long or often used
1098 The shell expands command aliases (i.e. substitutes the alias name
1099 for its value) when it reads the first word of a command.
1100 An expanded alias is re-processed to check for more aliases.
1101 If a command alias ends in a
1102 space or tab, the following word is also checked for alias expansion.
1103 The alias expansion process stops when a word that is not an alias is found,
1104 when a quoted word is found, or when an alias word that is currently being
1106 Aliases are specifically an interactive feature: while they do happen
1107 to work in scripts and on the command line in some cases, aliases are
1108 expanded during lexing, so their use must be in a separate command tree
1109 from their definition; otherwise, the alias will not be found.
1110 Noticeably, command lists (separated by semicolon, in command substitutions
1111 also by newline) may be one same parse tree.
1113 The following command aliases are defined automatically by the shell:
1114 .Bd -literal -offset indent
1115 autoload=\*(aqtypeset \-fu\*(aq
1116 functions=\*(aqtypeset \-f\*(aq
1117 hash=\*(aqalias \-t\*(aq
1118 history=\*(aqfc \-l\*(aq
1119 integer=\*(aqtypeset \-i\*(aq
1120 local=\*(aqtypeset\*(aq
1121 login=\*(aqexec login\*(aq
1122 nameref=\*(aqtypeset \-n\*(aq
1123 nohup=\*(aqnohup \*(aq
1124 r=\*(aqfc \-e \-\*(aq
1125 stop=\*(aqkill \-STOP\*(aq
1126 suspend=\*(aqkill \-STOP $$\*(aq
1127 type=\*(aqwhence \-v\*(aq
1130 Tracked aliases allow the shell to remember where it found a particular
1132 The first time the shell does a path search for a command that is
1133 marked as a tracked alias, it saves the full path of the command.
1135 time the command is executed, the shell checks the saved path to see that it
1136 is still valid, and if so, avoids repeating the path search.
1137 Tracked aliases can be listed and created using
1139 Note that changing the
1141 parameter clears the saved paths for all tracked aliases.
1144 option is set (i.e.\&
1145 .Ic set \-o Ic trackall
1148 the shell tracks all commands.
1149 This option is set automatically for non-interactive shells.
1150 For interactive shells, only the following commands are
1151 automatically tracked:
1171 The first step the shell takes in executing a simple-command is to perform
1172 substitutions on the words of the command.
1173 There are three kinds of
1174 substitution: parameter, command, and arithmetic.
1175 Parameter substitutions,
1176 which are described in detail in the next section, take the form
1179 .Pf ${ Ns Ar ... Ns } ;
1180 command substitutions take the form
1181 .Pf $( Ns Ar command Ns \&)
1183 .Pf \` Ns Ar command Ns \`
1184 or (executed in the current environment)
1185 .Pf ${\ \& Ar command Ns \&;}
1186 and strip trailing newlines;
1187 and arithmetic substitutions take the form
1188 .Pf $(( Ns Ar expression Ns )) .
1189 Parsing the current-environment command substitution requires a space,
1190 tab or newline after the opening brace and that the closing brace be
1191 recognised as a keyword (i.e. is preceded by a newline or semicolon).
1192 They are also called funsubs (function substitutions) and behave like
1199 terminates the parent shell.
1201 Another variant of substitution are the valsubs (value substitutions)
1202 .Pf ${\*(Ba\& Ns Ar command Ns \&;}
1203 which are also executed in the current environment, like funsubs, but
1204 share their I/O with the parent; instead, they evaluate to whatever
1205 the, initially empty, expression-local variable
1207 is set to within the
1208 .Ar command Ns No s .
1210 If a substitution appears outside of double quotes, the results of the
1211 substitution are generally subject to word or field splitting according to
1212 the current value of the
1217 parameter specifies a list of octets which are used to break a string up
1218 into several words; any octets from the set space, tab, and newline that
1222 .Dq IFS whitespace .
1223 Sequences of one or more
1225 whitespace octets, in combination with zero or one
1227 whitespace octets, delimit a field.
1228 As a special case, leading and trailing
1230 whitespace and trailing
1232 non-whitespace are stripped (i.e. no leading or trailing empty field
1233 is created by it); leading
1235 whitespace does create an empty field.
1240 .Dq \*(Ltspace\*(Gt: ,
1242 .Dq \*(Ltspace\*(GtA\*(Ltspace\*(Gt:\*(Ltspace\*(Gt\*(Ltspace\*(GtB::D ,
1243 the substitution for $VAR results in four fields:
1252 parameter is set to the
1254 string, no field splitting is done; if the parameter is unset, the default
1255 value of space, tab, and newline is used.
1257 Also, note that the field splitting applies only to the immediate result of
1259 Using the previous example, the substitution for $VAR:E
1260 results in the fields:
1273 This behavior is POSIX compliant, but incompatible with some other shell
1274 implementations which do field splitting on the word which contained the
1277 as a general whitespace delimiter.
1279 The results of substitution are, unless otherwise specified, also subject to
1280 brace expansion and file name expansion (see the relevant sections below).
1282 A command substitution is replaced by the output generated by the specified
1283 command which is run in a subshell.
1285 .Pf $( Ns Ar command Ns \&)
1287 .Pf ${\ \& Ar command Ns \&;}
1288 substitutions, normal quoting rules are used when
1290 is parsed; however, for the deprecated
1291 .Pf \` Ns Ar command Ns \`
1301 followed by any other character is unchanged).
1302 As a special case in command substitutions, a command of the form
1304 is interpreted to mean substitute the contents of
1308 has the same effect as
1311 Note that some shells do not use a recursive parser for command substitutions,
1312 leading to failure for certain constructs; to be portable, use as workaround
1313 .Ql x=$(cat) \*(Lt\*(Lt"EOF"
1314 (or the newline-keeping
1315 .Ql x=\*(Lt\*(Lt"EOF"
1316 extension) instead to merely slurp the string.
1318 recommends to use case statements of the form
1319 .Ql "x=$(case $foo in (bar) echo $bar ;; (*) echo $baz ;; esac)"
1320 instead, which would work but not serve as example for this portability issue.
1321 .Bd -literal -offset indent
1322 x=$(case $foo in bar) echo $bar ;; *) echo $baz ;; esac)
1323 # above fails to parse on old shells; below is the workaround
1324 x=$(eval $(cat)) \*(Lt\*(Lt"EOF"
1325 case $foo in bar) echo $bar ;; *) echo $baz ;; esac
1329 Arithmetic substitutions are replaced by the value of the specified expression.
1330 For example, the command
1331 .Ic print $((2+3*4))
1334 .Sx Arithmetic expressions
1335 for a description of an expression.
1337 Parameters are shell variables; they can be assigned values and their values
1338 can be accessed using a parameter substitution.
1339 A parameter name is either one
1340 of the special single punctuation or digit character parameters described
1341 below, or a letter followed by zero or more letters or digits
1346 The latter form can be treated as arrays by appending an array index of the
1351 is an arithmetic expression.
1354 are limited to the range 0 through 4294967295, inclusive.
1355 That is, they are a 32-bit unsigned integer.
1357 Parameter substitutions take the form
1359 .Pf ${ Ns Ar name Ns } ,
1362 .Pf ${ Ar name Oo Ar expr Oc }
1366 is a parameter name.
1367 Substitution of all array elements with
1368 .Pf ${ Ns Ar name Ns \&[*]}
1370 .Pf ${ Ns Ar name Ns \&[@]}
1371 works equivalent to $* and $@ for positional parameters.
1372 If substitution is performed on a parameter
1373 (or an array parameter element)
1374 that is not set, a null string is substituted unless the
1378 .Ic set Fl o Ic nounset
1382 is set, in which case an error occurs.
1384 Parameters can be assigned values in a number of ways.
1385 First, the shell implicitly sets some parameters like
1390 this is the only way the special single character parameters are set.
1391 Second, parameters are imported from the shell's environment at startup.
1392 Third, parameters can be assigned values on the command line: for example,
1398 multiple parameter assignments can be given on a single command line and they
1399 can be followed by a simple-command, in which case the assignments are in
1400 effect only for the duration of the command (such assignments are also
1401 exported; see below for the implications of this).
1402 Note that both the parameter name and the
1404 must be unquoted for the shell to recognise a parameter assignment.
1407 is also recognised; the old and new values are immediately concatenated.
1408 The fourth way of setting a parameter is with the
1414 commands; see their descriptions in the
1415 .Sx Command execution
1421 loops set parameters as well as the
1427 Lastly, parameters can be assigned values using assignment operators
1428 inside arithmetic expressions (see
1429 .Sx Arithmetic expressions
1432 .Pf ${ Ar name No = Ar value No }
1434 form of the parameter substitution (see below).
1436 Parameters with the export attribute (set using the
1440 commands, or by parameter assignments followed by simple commands) are put in
1441 the environment (see
1443 of commands run by the shell as
1444 .Ar name Ns = Ns Ar value
1446 The order in which parameters appear in the environment of a command is
1448 When the shell starts up, it extracts parameters and their values
1449 from its environment and automatically sets the export attribute for those
1452 Modifiers can be applied to the
1453 .Pf ${ Ns Ar name Ns }
1454 form of parameter substitution:
1457 .It ${ Ar name No :\- Ar word No }
1463 it is substituted; otherwise,
1467 .It ${ Ar name No :+ Ar word No }
1474 is substituted; otherwise, nothing is substituted.
1476 .It ${ Ar name No := Ar word No }
1482 it is substituted; otherwise, it is assigned
1484 and the resulting value of
1488 .It ${ Ar name No :? Ar word No }
1494 it is substituted; otherwise,
1496 is printed on standard error (preceded by
1498 and an error occurs (normally causing termination of a shell script, function,
1499 or script sourced using the
1504 is omitted, the string
1505 .Dq parameter null or not set
1509 is a variable which expands to the null string, the
1510 error message is also printed.
1513 Note that, for all of the above,
1515 is actually considered quoted, and special parsing rules apply.
1516 The parsing rules also differ on whether the expression is double-quoted:
1518 then uses double-quoting rules, except for the double quote itself
1520 and the closing brace, which, if backslash escaped, gets quote removal applied.
1522 In the above modifiers, the
1524 can be omitted, in which case the conditions only depend on
1526 being set (as opposed to set and not
1530 is needed, parameter, command, arithmetic, and tilde substitution are performed
1533 is not needed, it is not evaluated.
1535 The following forms of parameter substitution can also be used (if
1537 is an array, its element #0 will be substituted in a scalar context):
1539 .Bl -tag -width Ds -compact
1540 .It Pf ${# Ns Ar name Ns \&}
1541 The number of positional parameters if
1546 or not specified; otherwise the length
1548 of the string value of parameter
1551 .It Pf ${# Ns Ar name Ns \&[*]}
1552 .It Pf ${# Ns Ar name Ns \&[@]}
1553 The number of elements in the array
1556 .It Pf ${% Ns Ar name Ns \&}
1558 .Pq in screen columns
1559 of the string value of parameter
1562 .Pf ${ Ns Ar name Ns }
1563 contains a control character.
1565 .It Pf ${! Ns Ar name Ns }
1566 The name of the variable referred to by
1572 is a name reference (bound variable), created by the
1574 command (which is an alias for
1575 .Ic typeset Fl n ) .
1577 .It Pf ${! Ns Ar name Ns \&[*]}
1578 .It Pf ${! Ns Ar name Ns \&[@]}
1579 The names of indices (keys) in the array
1585 .Pf # Ar pattern No }
1589 .Pf ## Ar pattern No }
1594 matches the beginning of the value of parameter
1596 the matched text is deleted from the result of substitution.
1599 results in the shortest match, and two
1600 of them result in the longest match.
1601 Cannot be applied to a vector
1602 .Pq ${*} or ${@} or ${array[*]} or ${array[@]} .
1607 .Pf % Ar pattern No }
1611 .Pf %% Ar pattern No }
1614 Like ${..#..} substitution, but it deletes from the end of the value.
1615 Cannot be applied to a vector.
1620 .Pf / Ar pattern / Ar string No }
1624 .Pf // Ar pattern / Ar string No }
1627 Like ${..#..} substitution, but it replaces the longest match of
1629 anchored anywhere in the value, with
1635 it is anchored at the beginning of the value; if it begins with
1637 it is anchored at the end.
1638 Patterns that are empty or consist only of wildcards are invalid.
1641 replaces the first occurence of the search
1643 and two of them replace all occurences.
1648 is replaced by the empty string, i.e. deleted.
1649 Cannot be applied to a vector.
1650 Inefficiently implemented, may be slow.
1654 .Pf ${ Ar name : Ns Ar pos
1655 .Pf : Ns Ar len Ns }
1662 starting at position
1672 is negative, counting starts at the end of the string; if it
1673 is omitted, it defaults to 0.
1676 is omitted or greater than the length of the remaining string,
1677 all of it is substituted.
1682 are evaluated as arithmetic expressions.
1685 must start with a space, opening parenthesis or digit to be recognised.
1686 Cannot be applied to a vector.
1690 .Pf @# Ns Oo Ar seed Oc Ns }
1692 The internal hash of the expansion of
1694 with an optional (defaulting to zero)
1696 At the moment, this is NZAAT (a 32-bit hash based on
1697 Bob Jenkins' one-at-a-time hash), but this is not set.
1698 This is the hash the shell uses internally for its associative arrays.
1700 .It Pf ${ Ns Ar name Ns @Q}
1701 A quoted expression safe for re-entry, whose value is the value of the
1703 parameter, is substituted.
1708 may need extended globbing pattern
1711 .Pq \&\*(aq...\&\*(aq
1714 quote escaping unless
1718 The following special parameters are implicitly set by the shell and cannot be
1719 set directly using assignments:
1720 .Bl -tag -width "1 .. 9"
1722 Process ID of the last background process started.
1723 If no background processes have been started, the parameter is not set.
1725 The number of positional parameters ($1, $2, etc.).
1727 The PID of the shell, or the PID of the original shell if it is a subshell.
1730 use this mechanism for generating temporary file names; see
1734 The concatenation of the current single letter options (see the
1736 command below for a list of options).
1738 The exit status of the last non-asynchronous command executed.
1739 If the last command was killed by a signal,
1741 is set to 128 plus the signal number.
1743 The name of the shell, determined as follows:
1744 the first argument to
1746 if it was invoked with the
1748 option and arguments were given; otherwise the
1750 argument, if it was supplied;
1751 or else the basename the shell was invoked with (i.e.\&
1754 is also set to the name of the current script or
1755 the name of the current function, if it was defined with the
1757 keyword (i.e. a Korn shell style function).
1759 The first nine positional parameters that were supplied to the shell, function,
1760 or script sourced using the
1763 Further positional parameters may be accessed using
1764 .Pf ${ Ar number Ns } .
1766 All positional parameters (except 0), i.e. $1, $2, $3, ...
1769 outside of double quotes, parameters are separate words (which are subjected
1770 to word splitting); if used within double quotes, parameters are separated
1771 by the first character of the
1773 parameter (or the empty string if
1780 unless it is used inside double quotes, in which case a separate word is
1781 generated for each positional parameter.
1782 If there are no positional parameters, no word is generated.
1784 can be used to access arguments, verbatim, without losing
1786 arguments or splitting arguments with spaces.
1789 The following parameters are set and/or used by the shell:
1790 .Bl -tag -width "KSH_VERSION"
1793 When an external command is executed by the shell, this parameter is set in the
1794 environment of the new process to the path of the executed command.
1795 In interactive use, this parameter is also set in the parent shell to the last
1796 word of the previous command.
1798 The PID of the shell or subshell.
1803 It works the same way as
1805 for those directories not beginning with
1812 is set and does not contain
1814 or contains an empty path, the current directory is not searched.
1817 built-in command will display the resulting directory when a match is found
1818 in any search path other than the empty path.
1820 Set to the number of columns on the terminal or window.
1821 Always set, defaults to 80, unless the
1822 value as reported by
1824 is non-zero and sane enough (minimum is 12x3); similar for
1826 This parameter is used by the interactive line editing modes, and by the
1831 commands to format information columns.
1832 Importing from the environment or unsetting this parameter removes the
1833 binding to the actual terminal size in favour of the provided value.
1835 If this parameter is found to be set after any profile files are executed, the
1836 expanded value is used as a shell startup file.
1837 It typically contains function and alias definitions.
1839 Integer value of the shell's
1842 It indicates the reason the last system call failed.
1843 Not yet implemented.
1845 If set, this parameter is assumed to contain the shell that is to be used to
1846 execute commands that
1848 fails to execute and which do not start with a
1852 The editor used by the
1854 command (see below).
1858 but used when an undefined function is executed to locate the file defining the
1860 It is also searched when a command can't be found using
1864 below for more information.
1866 The name of the file used to store command history.
1867 When assigned to, history is loaded from the specified file.
1868 Also, several invocations of the shell will share history if their
1870 parameters all point to the same file.
1875 isn't set, no history file is used.
1876 This is different from
1880 The number of commands normally stored for history.
1881 The default is 2047.
1883 The default directory for the
1885 command and the value substituted for an unqualified
1891 Internal field separator, used during substitution and by the
1893 command, to split values into distinct arguments; normally set to space, tab,
1900 This parameter is not imported from the environment when the shell is
1903 The effective group id of the shell.
1905 The real group id of the shell.
1907 The real user id of the shell.
1909 The name and version of the shell (read-only).
1910 See also the version commands in
1911 .Sx Emacs editing mode
1916 The line number of the function or shell script that is currently being
1919 Set to the number of lines on the terminal or window.
1920 Always set, defaults to 24.
1923 .It Ev EPOCHREALTIME
1924 Time since the epoch, as returned by
1925 .Xr gettimeofday 2 ,
1926 formatted as decimal
1932 padded to exactly six decimal digits.
1934 The previous working directory.
1937 has not successfully changed directories since the shell started, or if the
1938 shell doesn't know where it is.
1942 it contains the argument for a parsed option, if it requires one.
1944 The index of the next argument to be processed when using
1946 Assigning 1 to this parameter causes
1948 to process arguments from the beginning the next time it is invoked.
1950 A colon separated list of directories that are searched when looking for
1951 commands and files sourced using the
1953 command (see below).
1954 An empty string resulting from a leading or trailing
1955 colon, or two adjacent colons, is treated as a
1957 (the current directory).
1959 The process ID of the shell's process group leader.
1961 An array containing the errorlevel (exit status) codes,
1962 one by one, of the last pipeline run in the foreground.
1964 The process ID of the shell's parent.
1966 The primary prompt for interactive shells.
1967 Parameter, command, and arithmetic
1968 substitutions are performed, and
1970 is replaced with the current command number (see the
1975 can be put in the prompt by placing
1980 The default prompt is
1987 is invoked by root and
1991 character, the default value will be used even if
1993 already exists in the environment.
1997 distribution comes with a sample
1999 containing a sophisticated example, but you might like the following one
2000 (note that ${HOSTNAME:=$(hostname)} and the
2001 root-vs-user distinguishing clause are (in this example) executed at
2003 assignment time, while the $USER and $PWD are escaped
2004 and thus will be evaluated each time a prompt is displayed):
2006 PS1=\*(aq${USER:=$(id \-un)}\*(aq"@${HOSTNAME:=$(hostname)}:\e$PWD $(
2007 if (( USER_ID )); then print \e$; else print \e#; fi) "
2010 Note that since the command-line editors try to figure out how long the prompt
2011 is (so they know how far it is to the edge of the screen), escape codes in
2012 the prompt tend to mess things up.
2013 You can tell the shell not to count certain
2014 sequences (such as escape codes) by prefixing your prompt with a
2015 character (such as Ctrl-A) followed by a carriage return and then delimiting
2016 the escape codes with this character.
2017 Any occurences of that character in the prompt are not printed.
2018 By the way, don't blame me for
2019 this hack; it's derived from the original
2021 which did print the delimiter character so you were out of luck
2022 if you did not have any non-printing characters.
2024 Since Backslashes and other special characters may be
2025 interpreted by the shell, to set
2027 either escape the backslash itself,
2028 or use double quotes.
2029 The latter is more practical.
2030 This is a more complex example,
2031 avoiding to directly enter special characters (for example with
2033 in the emacs editing mode),
2034 which embeds the current working directory,
2036 .Pq colour would work, too ,
2037 in the prompt string:
2038 .Bd -literal -offset indent
2040 PS1="$x$(print \e\er)$x$(tput smso)$x\e$PWD$x$(tput rmso)$x\*(Gt "
2043 Due to a strong suggestion from David G. Korn,
2045 now also supports the following form:
2046 .Bd -literal -offset indent
2047 PS1=$'\e1\er\e1\ee[7m\e1$PWD\e1\ee[0m\e1\*(Gt '
2050 Secondary prompt string, by default
2052 used when more input is needed to complete a command.
2056 statement when reading a menu selection.
2060 Used to prefix commands that are printed during execution tracing (see the
2063 Parameter, command, and arithmetic substitutions are performed
2064 before it is printed.
2067 You may want to set it to
2068 .Sq \&[$EPOCHREALTIME]\ \&
2069 instead, to include timestamps.
2071 The current working directory.
2074 if the shell doesn't know where it is.
2078 is referenced, it is assigned a number between 0 and 32767 from
2079 a Linear Congruential PRNG first.
2081 Default parameter for the
2083 command if no names are given.
2086 loops to store the value that is read from standard input.
2088 The number of seconds since the shell started or, if the parameter has been
2089 assigned an integer value, the number of seconds since the assignment plus the
2090 value that was assigned.
2092 If set to a positive integer in an interactive shell, it specifies the maximum
2093 number of seconds the shell will wait for input after printing the primary
2096 If the time is exceeded, the shell exits.
2098 The directory temporary shell files are created in.
2099 If this parameter is not
2100 set, or does not contain the absolute path of a writable directory, temporary
2101 files are created in
2104 The effective user id of the shell.
2107 Tilde expansion which is done in parallel with parameter substitution, is done
2108 on words starting with an unquoted
2110 The characters following the tilde, up to the first
2112 if any, are assumed to be a login name.
2113 If the login name is empty,
2122 parameter is substituted, respectively.
2123 Otherwise, the password file is
2124 searched for the login name, and the tilde expression is substituted with the
2125 user's home directory.
2126 If the login name is not found in the password file or
2127 if any quoting or parameter substitution occurs in the login name, no
2128 substitution is performed.
2130 In parameter assignments
2131 (such as those preceding a simple-command or those occurring
2139 tilde expansion is done after any assignment
2140 (i.e. after the equals sign)
2141 or after an unquoted colon
2143 login names are also delimited by colons.
2145 The home directory of previously expanded login names are cached and re-used.
2148 command may be used to list, change, and add to this cache (e.g.\&
2149 .Ic alias \-d fac=/usr/local/facilities; cd \*(TIfac/bin ) .
2150 .Ss Brace expansion (alteration)
2151 Brace expressions take the following form:
2152 .Bd -unfilled -offset indent
2155 .Ar prefix No { Ar str1 No ,...,
2156 .Ar strN No } Ar suffix
2161 The expressions are expanded to
2163 words, each of which is the concatenation of
2170 expands to four words:
2176 As noted in the example, brace expressions can be nested and the resulting
2177 words are not sorted.
2178 Brace expressions must contain an unquoted comma
2180 for expansion to occur (e.g.\&
2185 Brace expansion is carried out after parameter substitution
2186 and before file name generation.
2187 .Ss File name patterns
2188 A file name pattern is a word containing one or more unquoted
2198 Once brace expansion has been performed, the shell replaces file
2199 name patterns with the sorted names of all the files that match the pattern
2200 (if no files match, the word is left unchanged).
2201 The pattern elements have the following meaning:
2204 Matches any single character.
2206 Matches any sequence of octets.
2208 Matches any of the octets inside the brackets.
2209 Ranges of octets can be specified by separating two octets by a
2216 In order to represent itself, a
2218 must either be quoted or the first or last octet in the octet list.
2221 must be quoted or the first octet in the list if it is to represent itself
2222 instead of the end of the list.
2225 appearing at the start of the list has special meaning (see below), so to
2226 represent itself it must be quoted or appear later in the list.
2229 except it matches any octet not inside the brackets.
2231 .It *( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2233 Matches any string of octets that matches zero or more occurrences of the
2235 Example: The pattern
2244 .It +( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2246 Matches any string of octets that matches one or more occurrences of the
2248 Example: The pattern
2256 .It ?( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2258 Matches the empty string or a string that matches one of the specified
2260 Example: The pattern
2262 only matches the strings
2268 .It @( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2270 Matches a string that matches one of the specified patterns.
2271 Example: The pattern
2273 only matches the strings
2278 .It !( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
2280 Matches any string that does not match one of the specified patterns.
2281 Examples: The pattern
2283 matches all strings except
2289 matches no strings; the pattern
2291 matches all strings (think about it).
2294 Note that complicated globbing, especially with alternatives,
2295 is slow; using separate comparisons may (or may not) be faster.
2313 Note that none of the above pattern elements match either a period
2315 at the start of a file name or a slash
2317 even if they are explicitly used in a [..] sequence; also, the names
2321 are never matched, even by the pattern
2326 option is set, any directories that result from file name generation are marked
2329 .Ss Input/output redirection
2330 When a command is executed, its standard input, standard output, and standard
2331 error (file descriptors 0, 1, and 2, respectively) are normally inherited from
2333 Three exceptions to this are commands in pipelines, for which
2334 standard input and/or standard output are those set up by the pipeline,
2335 asynchronous commands created when job control is disabled, for which standard
2336 input is initially set to be from
2338 and commands for which any of the following redirections have been specified:
2339 .Bl -tag -width XXxxmarker
2341 Standard output is redirected to
2345 does not exist, it is created; if it does exist, is a regular file, and the
2347 option is set, an error occurs; otherwise, the file is truncated.
2348 Note that this means the command
2349 .Ic cmd \*(Ltfoo \*(Gtfoo
2352 for reading and then truncate it when it opens it for writing, before
2354 gets a chance to actually read
2356 .It \*(Gt\*(Ba Ar file
2359 except the file is truncated, even if the
2362 .It \*(Gt\*(Gt Ar file
2367 exists it is appended to instead of being truncated.
2368 Also, the file is opened
2369 in append mode, so writes always go to the end of the file (see
2372 Standard input is redirected from
2374 which is opened for reading.
2375 .It \*(Lt\*(Gt Ar file
2378 except the file is opened for reading and writing.
2379 .It \*(Lt\*(Lt Ar marker
2380 After reading the command line containing this kind of redirection (called a
2381 .Dq here document ) ,
2382 the shell copies lines from the command source into a temporary file until a
2386 When the command is executed, standard input is redirected from the
2390 contains no quoted characters, the contents of the temporary file are processed
2391 as if enclosed in double quotes each time the command is executed, so
2392 parameter, command, and arithmetic substitutions are performed, along with
2403 If multiple here documents are used on the same command line, they are saved in
2408 is given, the here document ends at the next
2410 and substitution will be performed.
2413 is only a set of either single
2417 quotes with nothing in between, the here document ends at the next empty line
2418 and substitution will not be performed.
2419 .It \*(Lt\*(Lt\- Ar marker
2422 except leading tabs are stripped from lines in the here document.
2423 .It \*(Lt\*(Lt\*(Lt Ar word
2430 This is called a here string.
2432 Standard input is duplicated from file descriptor
2435 can be a number, indicating the number of an existing file descriptor;
2438 indicating the file descriptor associated with the output of the current
2439 co-process; or the character
2441 indicating standard input is to be closed.
2444 is limited to a single digit in most shell implementations.
2448 except the operation is done on standard output.
2451 .Ic \*(Gt Ar file 2\*(Gt&1 .
2454 extension supported by
2456 which also supports the preceding explicit fd number, for example,
2459 .Ic 3\*(Gt Ar file 2\*(Gt&3
2462 but a syntax error in GNU
2468 shell options disable parsing of this redirection;
2469 it's a compatibility feature to legacy scripts, to
2470 not be used when writing new shell code.
2472 .No &\*(Gt\*(Ba Ar file ,
2473 .No &\*(Gt\*(Gt Ar file ,
2477 .Ic \*(Gt\*(Ba Ar file ,
2478 .Ic \*(Gt\*(Gt Ar file ,
2489 In any of the above redirections, the file descriptor that is redirected
2490 (i.e. standard input or standard output)
2491 can be explicitly given by preceding the
2492 redirection with a number (portably, only a single digit).
2493 Parameter, command, and arithmetic
2494 substitutions, tilde substitutions, and (if the shell is interactive)
2495 file name generation are all performed on the
2500 arguments of redirections.
2501 Note, however, that the results of any file name
2502 generation are only used if a single file is matched; if multiple files match,
2503 the word with the expanded file name generation characters is used.
2505 that in restricted shells, redirections which can create files cannot be used.
2507 For simple-commands, redirections may appear anywhere in the command; for
2513 any redirections must appear at the end.
2514 Redirections are processed after
2515 pipelines are created and in the order they are given, so the following
2516 will print an error with a line number prepended to it:
2518 .D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt/dev/null \*(Ba pr \-n \-t
2520 File descriptors created by input/output redirections are private to the
2521 Korn shell, but passed to sub-processes if
2526 .Ss Arithmetic expressions
2527 Integer arithmetic expressions can be used with the
2529 command, inside $((..)) expressions, inside array references (e.g.\&
2530 .Ar name Ns Bq Ar expr ) ,
2531 as numeric arguments to the
2533 command, and as the value of an assignment to an integer parameter.
2535 Expressions are calculated using signed arithmetic and the
2537 type (a 32-bit signed integer), unless they begin with a sole
2539 character, in which case they use
2541 .Po a 32-bit unsigned integer Pc .
2543 Expressions may contain alpha-numeric parameter identifiers, array references,
2544 and integer constants and may be combined with the following C operators
2545 (listed and grouped in increasing order of precedence):
2548 .Bd -literal -offset indent
2549 + \- ! \*(TI ++ \-\-
2553 .Bd -literal -offset indent
2555 = += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt= \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
2562 \*(Lt \*(Lt= \*(Gt \*(Gt=
2563 \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt \*(Lt\*(Lt \*(Gt\*(Gt
2569 .Bd -literal -offset indent
2570 ?: (precedence is immediately higher than assignment)
2574 .Bd -literal -offset indent
2578 Integer constants and expressions are calculated using an exactly 32-bit
2579 wide, signed or unsigned, type with silent wraparound on integer overflow.
2580 Integer constants may be specified with arbitrary bases using the notation
2581 .Ar base Ns # Ns Ar number ,
2584 is a decimal integer specifying the base, and
2586 is a number in the specified base.
2587 Additionally, base-16 integers may be specified by prefixing them with
2589 .Pq case-insensitive
2590 in all forms of arithmetic expressions, except as numeric arguments to the
2593 Prefixing numbers with a sole digit zero
2595 leads to the shell interpreting it as base-8 integer in
2599 historically, (pd)ksh has never done so either anyway,
2600 and it's unsafe to do that, but POSIX demands it nowadays.
2603 extension, numbers to the base of one are treated as either (8-bit
2604 transparent) ASCII or Unicode codepoints, depending on the shell's
2606 flag (current setting).
2615 Note that NUL bytes (integral value of zero) cannot be used.
2616 An unset or empty parameter evaluates to 0 in integer context.
2617 In Unicode mode, raw octets are mapped into the range EF80..EFFF as in
2618 OPTU-8, which is in the PUA and has been assigned by CSUR for this use.
2619 If more than one octet in ASCII mode, or a sequence of more than one
2620 octet not forming a valid and minimal CESU-8 sequence is passed, the
2621 behaviour is undefined (usually, the shell aborts with a parse error,
2622 but rarely, it succeeds, e.g. on the sequence C2 20).
2623 That's why you should always use ASCII mode unless you know that the
2624 input is well-formed UTF-8 in the range of 0000..FFFD.
2626 The operators are evaluated as follows:
2627 .Bl -tag -width Ds -offset indent
2629 Result is the argument (included for completeness).
2634 the result is 1 if argument is zero, 0 if not.
2636 Arithmetic (bit-wise) NOT.
2638 Increment; must be applied to a parameter (not a literal or other expression).
2639 The parameter is incremented by 1.
2640 When used as a prefix operator, the result
2641 is the incremented value of the parameter; when used as a postfix operator, the
2642 result is the original value of the parameter.
2646 except the parameter is decremented by 1.
2648 Separates two arithmetic expressions; the left-hand side is evaluated first,
2650 The result is the value of the expression on the right-hand side.
2652 Assignment; the variable on the left is set to the value on the right.
2654 .No += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt=
2655 .No \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
2657 Assignment operators.
2672 with any operator precedence in
2677 is the same as specifying
2678 .Dq var1 = var1 * (5 + 3) .
2681 the result is 1 if either argument is non-zero, 0 if not.
2682 The right argument is evaluated only if the left argument is zero.
2685 the result is 1 if both arguments are non-zero, 0 if not.
2686 The right argument is evaluated only if the left argument is non-zero.
2688 Arithmetic (bit-wise) OR.
2690 Arithmetic (bit-wise) XOR
2693 Arithmetic (bit-wise) AND.
2695 Equal; the result is 1 if both arguments are equal, 0 if not.
2697 Not equal; the result is 0 if both arguments are equal, 1 if not.
2699 Less than; the result is 1 if the left argument is less than the right, 0 if
2701 .It \*(Lt= \*(Gt \*(Gt=
2702 Less than or equal, greater than or equal, greater than.
2705 .It \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt
2706 Rotate left (right); the result is similar to shift (see
2708 except that the bits shifted out at one end are shifted in
2709 at the other end, instead of zero or sign bits.
2710 .It \*(Lt\*(Lt \*(Gt\*(Gt
2711 Shift left (right); the result is the left argument with its bits shifted left
2712 (right) by the amount given in the right argument.
2714 Addition, subtraction, multiplication, and division.
2716 Remainder; the result is the remainder of the division of the left argument by
2727 is non-zero, the result is
2729 otherwise the result is
2731 The non-result argument is not evaluated.
2734 A co-process (which is a pipeline created with the
2736 operator) is an asynchronous process that the shell can both write to (using
2738 and read from (using
2740 The input and output of the co-process can also be manipulated using
2744 redirections, respectively.
2745 Once a co-process has been started, another can't
2746 be started until the co-process exits, or until the co-process's input has been
2748 .Ic exec Ar n Ns Ic \*(Gt&p
2750 If a co-process's input is redirected in this way, the next
2751 co-process to be started will share the output with the first co-process,
2752 unless the output of the initial co-process has been redirected using an
2753 .Ic exec Ar n Ns Ic \*(Lt&p
2756 Some notes concerning co-processes:
2759 The only way to close the co-process's input (so the co-process reads an
2760 end-of-file) is to redirect the input to a numbered file descriptor and then
2761 close that file descriptor:
2762 .Ic exec 3\*(Gt&p; exec 3\*(Gt&\-
2764 In order for co-processes to share a common output, the shell must keep the
2765 write portion of the output pipe open.
2766 This means that end-of-file will not be
2767 detected until all co-processes sharing the co-process's output have exited
2768 (when they all exit, the shell closes its copy of the pipe).
2770 avoided by redirecting the output to a numbered file descriptor (as this also
2771 causes the shell to close its copy).
2772 Note that this behaviour is slightly
2773 different from the original Korn shell which closes its copy of the write
2774 portion of the co-process output when the most recently started co-process
2775 (instead of when all sharing co-processes) exits.
2780 signals during writes if the signal is not being trapped or ignored; the same
2781 is true if the co-process input has been duplicated to another file descriptor
2783 .Ic print \-u Ns Ar n
2787 Functions are defined using either Korn shell
2788 .Ic function Ar function-name
2789 syntax or the Bourne/POSIX shell
2790 .Ar function-name Ns \&()
2791 syntax (see below for the difference between the two forms).
2794 (i.e. scripts sourced using the
2797 in that they are executed in the current environment.
2800 shell arguments (i.e. positional parameters $1, $2, etc.)\&
2801 are never visible inside them.
2802 When the shell is determining the location of a command, functions
2803 are searched after special built-in commands, before builtins and the
2807 An existing function may be deleted using
2808 .Ic unset Fl f Ar function-name .
2809 A list of functions can be obtained using
2811 and the function definitions can be listed using
2815 command (which is an alias for
2817 may be used to create undefined functions: when an undefined function is
2818 executed, the shell searches the path specified in the
2820 parameter for a file with the same name as the function which, if found, is
2822 If after executing the file the named function is found to
2823 be defined, the function is executed; otherwise, the normal command search is
2824 continued (i.e. the shell searches the regular built-in command table and
2826 Note that if a command is not found using
2828 an attempt is made to autoload a function using
2830 (this is an undocumented feature of the original Korn shell).
2832 Functions can have two attributes,
2836 which can be set with
2841 When a traced function is executed, the shell's
2843 option is turned on for the function's duration.
2846 attribute of functions is currently not used.
2847 In the original Korn shell,
2848 exported functions are visible to shell scripts that are executed.
2850 Since functions are executed in the current shell environment, parameter
2851 assignments made inside functions are visible after the function completes.
2852 If this is not the desired effect, the
2854 command can be used inside a function to create a local parameter.
2858 uses static scoping (one global scope, one local scope per function)
2859 and allows local variables only on Korn style functions, whereas
2861 uses dynamic scoping (nested scopes of varying locality).
2862 Note that special parameters (e.g.\&
2864 can't be scoped in this way.
2866 The exit status of a function is that of the last command executed in the
2868 A function can be made to finish immediately using the
2870 command; this may also be used to explicitly specify the exit status.
2872 Functions defined with the
2874 reserved word are treated differently in the following ways from functions
2880 The $0 parameter is set to the name of the function
2881 (Bourne-style functions leave $0 untouched).
2883 Parameter assignments preceding function calls are not kept in the shell
2884 environment (executing Bourne-style functions will keep assignments).
2887 is saved/reset and restored on entry and exit from the function so
2889 can be used properly both inside and outside the function (Bourne-style
2894 inside a function interferes with using
2896 outside the function).
2898 Bourne-style function definitions take precedence over alias dereferences
2899 and remove alias definitions upon encounter, while aliases take precedence
2900 over Korn-style functions.
2903 In the future, the following differences may also be added:
2906 A separate trap/signal environment will be used during the execution of
2908 This will mean that traps set inside a function will not affect the
2909 shell's traps and signals that are not ignored in the shell (but may be
2910 trapped) will have their default effect in a function.
2912 The EXIT trap, if set in a function, will be executed after the function
2915 .Ss Command execution
2916 After evaluation of command-line arguments, redirections, and parameter
2917 assignments, the type of command is determined: a special built-in command,
2918 a function, a normal builtin, or the name of a file to execute found using the
2921 The checks are made in the above order.
2922 Special built-in commands differ from other commands in that the
2924 parameter is not used to find them, an error during their execution can
2925 cause a non-interactive shell to exit, and parameter assignments that are
2926 specified before the command are kept after the command completes.
2927 Regular built-in commands are different only in that the
2929 parameter is not used to find them.
2933 and POSIX differ somewhat in which commands are considered
2936 POSIX special built-in utilities:
2938 .Ic \&. , \&: , break , continue ,
2939 .Ic eval , exec , exit , export ,
2940 .Ic readonly , return , set , shift ,
2941 .Ic times , trap , unset
2945 commands keeping assignments:
2947 .Ic builtin , global , typeset , wait
2949 Builtins that are not special:
2951 .Ic [ , alias , bg , bind ,
2952 .Ic cat , cd , command , echo ,
2953 .Ic false , fc , fg , getopts ,
2954 .Ic jobs , kill , let , mknod ,
2955 .Ic print , pwd , read , realpath ,
2956 .Ic rename , sleep , test , true ,
2957 .Ic ulimit , umask , unalias , whence
2959 Once the type of command has been determined, any command-line parameter
2960 assignments are performed and exported for the duration of the command.
2962 The following describes the special and regular built-in commands:
2964 .Bl -tag -width false -compact
2965 .It Ic \&. Ar file Op Ar arg ...
2969 Execute the commands in
2971 in the current environment.
2972 The file is searched for in the directories of
2974 If arguments are given, the positional parameters may be used to access them
2978 If no arguments are given, the positional parameters are
2979 those of the environment the command is used in.
2981 .It Ic \&: Op Ar ...
2983 Exit status is set to zero.
2985 .It Ic \&[ Ar expression Ic \&]
2990 .Oo Fl d \*(Ba t Oo Fl r Oc \*(Ba
2995 .Op Ns = Ns Ar value
3001 For any name without a value, the existing alias is listed.
3002 Any name with a value defines an alias (see
3006 When listing aliases, one of two formats is used.
3007 Normally, aliases are listed as
3008 .Ar name Ns = Ns Ar value ,
3012 If options were preceded with
3016 is given on the command line, only
3022 option causes directory aliases which are used in tilde expansion to be
3029 option is used, each alias is prefixed with the string
3034 option indicates that tracked aliases are to be listed/set (values specified on
3035 the command line are ignored for tracked aliases).
3038 option indicates that all tracked aliases are to be reset.
3044 the export attribute of an alias, or, if no names are given, lists the aliases
3045 with the export attribute (exporting an alias has no effect).
3047 .It Ic bg Op Ar job ...
3048 Resume the specified stopped job(s) in the background.
3049 If no jobs are specified,
3054 below for more information.
3057 The current bindings are listed.
3062 instead lists the names of the functions to which keys may be bound.
3064 .Sx Emacs editing mode
3065 for more information.
3067 .It Xo Ic bind Op Fl m
3068 .Ar string Ns = Ns Op Ar substitute
3072 .Ar string Ns = Ns Op Ar editing-command
3075 The specified editing command is bound to the given
3077 which should consist of a control character
3078 optionally preceded by one of the two prefix characters
3079 and optionally succeded by a tilde character.
3082 will cause the editing command to be immediately invoked.
3085 flag is given, the specified input
3087 will afterwards be immediately replaced by the given
3089 string which may contain editing commands but not other macros.
3090 If a tilde postfix is given, a tilde trailing the one or
3091 two prefices and the control character is ignored, any
3092 other trailing character will be processed afterwards.
3094 Control characters may be written using caret notation
3095 i.e. \*(haX represents Ctrl-X.
3096 Note that although only two prefix characters (usually ESC and \*(haX)
3097 are supported, some multi-character sequences can be supported.
3099 The following default bindings show how the arrow keys, the home, end and
3100 delete key on a BSD wsvt25, xterm\-xfree86 or GNU screen terminal are bound
3101 (of course some escape sequences won't work out quite this nicely):
3102 .Bd -literal -offset indent
3103 bind \*(aq\*(haX\*(aq=prefix\-2
3104 bind \*(aq\*(ha[[\*(aq=prefix\-2
3105 bind \*(aq\*(haXA\*(aq=up\-history
3106 bind \*(aq\*(haXB\*(aq=down\-history
3107 bind \*(aq\*(haXC\*(aq=forward\-char
3108 bind \*(aq\*(haXD\*(aq=backward\-char
3109 bind \*(aq\*(haX1\*(TI\*(aq=beginning\-of\-line
3110 bind \*(aq\*(haX7\*(TI\*(aq=beginning\-of\-line
3111 bind \*(aq\*(haXH\*(aq=beginning\-of\-line
3112 bind \*(aq\*(haX4\*(TI\*(aq=end\-of\-line
3113 bind \*(aq\*(haX8\*(TI\*(aq=end\-of\-line
3114 bind \*(aq\*(haXF\*(aq=end\-of\-line
3115 bind \*(aq\*(haX3\*(TI\*(aq=delete\-char\-forward
3118 .It Ic break Op Ar level
3134 .Ar command Op Ar arg ...
3136 Execute the built-in command
3144 Read files sequentially, in command line order, and write them to
3150 or absent, read from standard input.
3151 Unless compiled with
3152 .Dv MKSH_NO_EXTERNAL_CAT ,
3153 if any options are given, an external
3155 utility is invoked instead if called from the shell.
3156 For direct builtin calls, the
3159 option is supported as a no-op.
3176 Set the working directory to
3180 is set, it lists the search path for the directory containing
3184 path means the current directory.
3187 is found in any component of the
3189 search path other than the
3191 path, the name of the new working directory will be written to standard output.
3194 is missing, the home directory
3201 the previous working directory is used (see the
3207 option (logical path) is used or if the
3209 option isn't set (see the
3211 command below), references to
3215 are relative to the path used to get to the directory.
3218 option (physical path) is used or if the
3222 is relative to the filesystem directory tree.
3227 parameters are updated to reflect the current and old working directory,
3231 option is set for physical filesystem traversal, and
3233 could not be set, the exit code is 1; greater than 1 if an
3234 error occurred, 0 otherwise.
3250 in the current directory, and the shell attempts to change to the new
3265 is executed exactly as if
3267 had not been specified, with two exceptions:
3270 cannot be a shell function;
3271 and secondly, special built-in commands lose their specialness
3272 (i.e. redirection and utility errors do not cause the shell to
3273 exit, and command assignments are not permanent).
3277 option is given, a default search path is used instead of the current value of
3279 the actual value of which is system dependent.
3283 option is given, instead of executing
3285 information about what would be executed is given (and the same is done for
3287 For special and regular built-in commands and functions, their names are simply
3288 printed; for aliases, a command that defines them is printed; and for commands
3289 found by searching the
3291 parameter, the full path of the command is printed.
3292 If no command is found
3293 (i.e. the path search fails), nothing is printed and
3295 exits with a non-zero status.
3300 option, except it is more verbose.
3302 .It Ic continue Op Ar level
3303 Jumps to the beginning of the
3321 this utility is not portable; use the Korn shell builtin
3325 Prints its arguments (separated by spaces) followed by a newline, to the
3327 The newline is suppressed if any of the arguments contain the
3332 command below for a list of other backslash sequences that are recognised.
3334 The options are provided for compatibility with
3339 option suppresses the trailing newline,
3341 enables backslash interpretation (a no-op, since this is normally done), and
3343 suppresses backslash interpretation.
3349 option is set or this is a direct builtin call, only the first argument
3350 is treated as an option, and only if it is exactly
3352 Backslash interpretation is disabled.
3354 .It Ic eval Ar command ...
3355 The arguments are concatenated (with spaces between them) to form a single
3356 string which the shell then parses and executes in the current environment.
3360 .Op Ar command Op Ar arg ...
3362 The command is executed without forking, replacing the shell process.
3364 If no command is given except for I/O redirection, the I/O redirection is
3365 permanent and the shell is
3367 Any file descriptors greater than 2 which are opened or
3369 in this way are not made available to other executed commands (i.e. commands
3370 that are not built-in to the shell).
3371 Note that the Bourne shell differs here;
3372 it does pass these file descriptors on.
3374 .It Ic exit Op Ar status
3375 The shell exits with the specified exit status.
3378 is not specified, the exit status is the current value of the
3385 .Op Ar parameter Ns Op = Ns Ar value
3387 Sets the export attribute of the named parameters.
3388 Exported parameters are passed in the environment to executed commands.
3389 If values are specified, the named parameters are also assigned.
3391 If no parameters are specified, all parameters with the export attribute
3392 set are printed one per line; either their names, or, if a
3394 with no option letter is specified, name=value pairs, or, with
3397 commands suitable for re-entry.
3400 A command that exits with a non-zero status.
3404 .Oo Fl e Ar editor \*(Ba
3407 .Op Ar first Op Ar last
3412 select commands from the history.
3413 Commands can be selected by history number
3414 or a string specifying the most recent command starting with that string.
3417 option lists the command on standard output, and
3419 inhibits the default command numbers.
3422 option reverses the order of the list.
3425 the selected commands are edited by the editor specified with the
3429 is specified, the editor specified by the
3431 parameter (if this parameter is not set,
3433 is used), and then executed by the shell.
3437 .Cm \-e \- \*(Ba Fl s
3439 .Op Ar old Ns = Ns Ar new
3442 Re-execute the selected command (the previous command by default) after
3443 performing the optional substitution of
3449 is specified, all occurrences of
3457 is identical: re-execute the selected command without invoking an editor.
3458 This command is usually accessed with the predefined:
3459 .Ic alias r=\*(aqfc \-e \-\*(aq
3461 .It Ic fg Op Ar job ...
3462 Resume the specified job(s) in the foreground.
3463 If no jobs are specified,
3468 below for more information.
3475 Used by shell procedures to parse the specified arguments (or positional
3476 parameters, if no arguments are given) and to check for legal options.
3478 contains the option letters that
3481 If a letter is followed by a colon, the option is expected to
3483 Options that do not take arguments may be grouped in a single argument.
3484 If an option takes an argument and the option character is not the
3485 last character of the argument it is found in, the remainder of the argument is
3486 taken to be the option's argument; otherwise, the next argument is the option's
3491 is invoked, it places the next option in the shell parameter
3493 and the index of the argument to be processed by the next call to
3495 in the shell parameter
3497 If the option was introduced with a
3499 the option placed in
3503 When an option requires an argument,
3505 places it in the shell parameter
3508 When an illegal option or a missing option argument is encountered, a question
3509 mark or a colon is placed in
3511 (indicating an illegal option or missing argument, respectively) and
3513 is set to the option character that caused the problem.
3516 does not begin with a colon, a question mark is placed in
3519 is unset, and an error message is printed to standard error.
3521 When the end of the options is encountered,
3523 exits with a non-zero exit status.
3524 Options end at the first (non-option
3525 argument) argument that does not start with a
3529 argument is encountered.
3531 Option parsing can be reset by setting
3533 to 1 (this is done automatically whenever the shell or a shell procedure is
3536 Warning: Changing the value of the shell parameter
3538 to a value other than 1, or parsing different sets of arguments without
3541 may lead to unexpected results.
3552 Without arguments, any hashed executable command pathnames are listed.
3555 option causes all hashed commands to be removed from the hash table.
3558 is searched as if it were a command name and added to the hash table if it is
3559 an executable command.
3566 Display information about the specified job(s); if no jobs are specified, all
3570 option causes information to be displayed only for jobs that have changed
3571 state since the last notification.
3574 option is used, the process ID of each process in a job is also listed.
3577 option causes only the process group of each job to be printed.
3580 below for the format of
3582 and the displayed job.
3586 .Oo Fl s Ar signame \*(Ba
3587 .No \- Ns Ar signum \*(Ba
3588 .No \- Ns Ar signame Oc
3589 .No { Ar job \*(Ba pid \*(Ba pgrp No }
3592 Send the specified signal to the specified jobs, process IDs, or process
3594 If no signal is specified, the
3597 If a job is specified, the signal is sent to the job's process group.
3600 below for the format of
3606 .Op Ar exit-status ...
3608 Print the signal name corresponding to
3610 If no arguments are specified, a list of all the signals, their numbers, and
3611 a short description of them are printed.
3613 .It Ic let Op Ar expression ...
3614 Each expression is evaluated (see
3615 .Sx Arithmetic expressions
3617 If all expressions are successfully evaluated, the exit status is 0 (1)
3618 if the last expression evaluated to non-zero (zero).
3619 If an error occurs during
3620 the parsing or evaluation of an expression, the exit status is greater than 1.
3621 Since expressions may need to be quoted,
3622 .No \&(( Ar expr No ))
3623 is syntactic sugar for
3624 .No let \&" Ns Ar expr Ns \&" .
3627 Internally used alias for
3643 Create a device special file.
3644 The file type may be
3646 (block type device),
3648 (character type device),
3651 .Pq named pipe , Tn FIFO .
3652 The file created may be modified according to its
3658 (major device number),
3661 (minor device number).
3665 for further information.
3669 .Oo Fl nprsu Ns Oo Ar n Oc \*(Ba
3674 prints its arguments on the standard output, separated by spaces and
3675 terminated with a newline.
3678 option suppresses the newline.
3679 By default, certain C escapes are translated.
3680 These include these mentioned in
3681 .Sx Backslash expansion
3684 which is equivalent to using the
3687 Backslash expansion may be inhibited with the
3692 option prints to the history file instead of standard output; the
3694 option prints to file descriptor
3698 defaults to 1 if omitted
3702 option prints to the co-process (see
3708 option is used to emulate, to some degree, the
3711 command which does not process
3713 sequences unless the
3718 option suppresses the trailing newline.
3720 .It Ic printf Ar format Op Ar arguments ...
3722 Approximately the same as the
3724 utility, except it uses the same
3725 .Sx Backslash expansion
3726 and I/O code and does hot handle floating point as the rest of
3728 This is not normally part of
3730 however, distributors may have added this as builtin as a speed hack.
3731 Do not use in new code.
3734 Print the present working directory.
3737 option is used or if the
3739 option isn't set (see the
3741 command below), the logical path is printed (i.e. the path used to
3743 to the current directory).
3746 option (physical path) is used or if the
3748 option is set, the path determined from the filesystem (by following
3750 directories to the root directory) is printed.
3764 Reads a line of input, separates the input into fields using the
3768 above), and assigns each field to the specified parameters
3770 If no parameters are specified, the
3772 parameter is used to store the result.
3777 options, only no or one parameter is accepted.
3778 If there are more parameters than fields, the extra parameters are set to
3779 the empty string or 0; if there are more fields than parameters, the last
3780 parameter is assigned the remaining fields (including the word separators).
3782 The options are as follows:
3783 .Bl -tag -width XuXnX
3785 Store the result into the parameter
3791 Store the result without word splitting into the parameter
3795 as array of characters (wide characters if the
3797 option is enacted, octets otherwise).
3799 Use the first byte of
3802 if empty, instead of the ASCII newline character as input line delimiter.
3804 Instead of reading till end-of-line, read exactly
3806 bytes; less if EOF or a timeout occurs.
3808 Instead of reading till end-of-line, read up to
3810 bytes but return as soon as any bytes are read, e.g.\& from a
3811 slow terminal device, or if EOF or a timeout occurs.
3813 Read from the currently active co-process, see
3815 above for details on this.
3817 Read from the file descriptor
3819 (defaults to 0, i.e.\& standard input).
3820 The argument must immediately follow the option character.
3822 Interrupt reading after
3824 seconds (specified as positive decimal value with an optional fractional part).
3826 Normally, the ASCII backslash character escapes the special
3827 meaning of the following character and is stripped from the input;
3829 does not stop when encountering a backslash-newline sequence and
3830 does not store that newline in the result.
3831 This option enables raw mode, in which backslashes are not processed.
3833 The input line is saved to the history.
3836 If the input is a terminal, both the
3840 options set it into raw mode;
3841 they read an entire file if \-1 is passed as
3845 The first parameter may have a question mark and a string appended to it, in
3846 which case the string is used as a prompt (printed to standard error before
3847 any input is read) if the input is a
3850 .Ic read nfoo?\*(aqnumber of foos: \*(aq ) .
3852 If no input is read or a timeout occurred,
3854 exits with a non-zero status.
3856 Another handy set of tricks:
3859 is run in a loop such as
3860 .Ic while read foo; do ...; done
3861 then leading whitespace will be removed (IFS) and backslashes processed.
3862 You might want to use
3863 .Ic while IFS= read \-r foo; do ...; done
3865 Similarily, when using the
3869 option might be prudent; the same applies for:
3870 .Bd -literal -offset indent
3871 find . \-type f \-print0 \*(Ba \e
3872 while IFS= read \-d \*(aq\*(aq \-r filename; do
3873 print \-r \-\- "found \*(Lt${filename#./}\*(Gt"
3877 The inner loop will be executed in a subshell and variable changes
3878 cannot be propagated if executed in a pipeline:
3879 .Bd -literal -offset indent
3880 bar \*(Ba baz \*(Ba while read foo; do ...; done
3883 Use co-processes instead:
3884 .Bd -literal -offset indent
3885 bar \*(Ba baz \*(Ba&
3886 while read \-p foo; do ...; done
3887 exec 3\*(Gt&p; exec 3\*(Gt&\-
3894 .Op Ns = Ns Ar value
3897 Sets the read-only attribute of the named parameters.
3898 If values are given,
3899 parameters are set to them before setting the attribute.
3901 made read-only, it cannot be unset and its value cannot be changed.
3903 If no parameters are specified, the names of all parameters with the read-only
3904 attribute are printed one per line, unless the
3906 option is used, in which case
3908 commands defining all read-only parameters, including their values, are
3916 Prints the resolved absolute pathname corresponding to
3922 it's also checked for existence and whether it is a directory; otherwise,
3924 returns 0 if the pathname either exists or can be created immediately,
3925 i.e. all but the last component exist and are directories.
3936 Both must be complete pathnames and on the same device.
3937 This builtin is intended for emergency situations where
3939 becomes unusable, and directly calls
3942 .It Ic return Op Ar status
3943 Returns from a function or
3945 script, with exit status
3949 is given, the exit status of the last executed command is used.
3950 If used outside of a function or
3952 script, it has the same effect as
3956 treats both profile and
3960 scripts, while the original Korn shell only treats profiles as
3965 .Ic set Op Ic +\-abCefhiklmnprsUuvXx
3966 .Op Ic +\-o Ar option
3973 command can be used to set
3977 shell options, set the positional parameters, or set an array parameter.
3978 Options can be changed using the
3982 is the long name of an option, or using the
3983 .Cm +\- Ns Ar letter
3986 is the option's single letter name (not all options have a single letter name).
3987 The following table lists both option letters (if they exist) and long names
3988 along with a description of what the option does:
3991 Sets the elements of the array parameter
3997 is used, the array is reset (i.e. emptied) first; if
3999 is used, the first N elements are set (where N is the number of arguments);
4000 the rest are left untouched.
4002 An alternative syntax for the command
4003 .Ic set \-A foo \-\- a b c
4004 which is compatible to
4007 and also supported by
4011 .Ic foo=(a b c); foo+=(d e)
4019 extension allows specifying the indices used for
4021 .Pq from the above example, Ic a b c
4023 .Ic set \-A foo \-\- [0]=a [1]=b [2]=c
4025 .Ic foo=([0]=a [1]=b [2]=c)
4026 which can also be written
4028 because indices are incremented automatically.
4029 .It Fl a \*(Ba Fl o Ic allexport
4030 All new parameters are created with the export attribute.
4031 .It Fl b \*(Ba Fl o Ic notify
4032 Print job notification messages asynchronously, instead of just before the
4034 Only used if job control is enabled
4036 .It Fl C \*(Ba Fl o Ic noclobber
4037 Prevent \*(Gt redirection from overwriting existing files.
4038 Instead, \*(Gt\*(Ba must be used to force an overwrite.
4039 .It Fl e \*(Ba Fl o Ic errexit
4040 Exit (after executing the
4042 trap) as soon as an error occurs or a command fails (i.e. exits with a
4044 This does not apply to commands whose exit status is
4045 explicitly tested by a shell construct such as
4056 only the status of the last command is tested.
4057 .It Fl f \*(Ba Fl o Ic noglob
4058 Do not expand file name patterns.
4059 .It Fl h \*(Ba Fl o Ic trackall
4060 Create tracked aliases for all executed commands (see
4063 Enabled by default for non-interactive shells.
4064 .It Fl i \*(Ba Fl o Ic interactive
4065 The shell is an interactive shell.
4066 This option can only be used when the shell is invoked.
4067 See above for a description of what this means.
4068 .It Fl k \*(Ba Fl o Ic keyword
4069 Parameter assignments are recognised anywhere in a command.
4070 .It Fl l \*(Ba Fl o Ic login
4071 The shell is a login shell.
4072 This option can only be used when the shell is invoked.
4073 See above for a description of what this means.
4074 .It Fl m \*(Ba Fl o Ic monitor
4075 Enable job control (default for interactive shells).
4076 .It Fl n \*(Ba Fl o Ic noexec
4077 Do not execute any commands.
4078 Useful for checking the syntax of scripts
4079 (ignored if interactive).
4080 .It Fl p \*(Ba Fl o Ic privileged
4081 The shell is a privileged shell.
4082 It is set automatically if, when the shell starts,
4083 the real UID or GID does not match
4084 the effective UID (EUID) or GID (EGID), respectively.
4085 See above for a description of what this means.
4086 .It Fl r \*(Ba Fl o Ic restricted
4087 The shell is a restricted shell.
4088 This option can only be used when the shell is invoked.
4089 See above for a description of what this means.
4090 .It Fl s \*(Ba Fl o Ic stdin
4091 If used when the shell is invoked, commands are read from standard input.
4092 Set automatically if the shell is invoked with no arguments.
4098 command it causes the specified arguments to be sorted before assigning them to
4099 the positional parameters (or to array
4104 .It Fl U \*(Ba Fl o Ic utf8\-mode
4105 Enable UTF-8 support in the
4106 .Sx Emacs editing mode
4107 and internal string handling functions.
4108 This flag is disabled by default, but can be enabled by setting it on the
4109 shell command line; is enabled automatically for interactive shells if
4110 requested at compile time, your system supports
4111 .Fn setlocale LC_CTYPE \&""
4113 .Fn nl_langinfo CODESET ,
4119 environment variables,
4120 and at least one of these returns something that matches
4124 case-insensitively; for direct builtin calls depending on the
4125 aforementioned environment variables; or for stdin or scripts,
4126 if the input begins with a UTF-8 Byte Order Mark.
4127 .It Fl u \*(Ba Fl o Ic nounset
4128 Referencing of an unset parameter, other than
4132 is treated as an error, unless one of the
4138 .It Fl v \*(Ba Fl o Ic verbose
4139 Write shell input to standard error as it is read.
4140 .It Fl X \*(Ba Fl o Ic markdirs
4141 Mark directories with a trailing
4143 during file name generation.
4144 .It Fl x \*(Ba Fl o Ic xtrace
4145 Print command trees when they are executed, preceded by
4149 Background jobs are run with lower priority.
4150 .It Fl o Ic braceexpand
4151 Enable brace expansion (a.k.a. alternation).
4152 This is enabled by default.
4153 If disabled, tilde expansion after an equals sign is disabled as a side effect.
4155 Enable BRL emacs-like command-line editing (interactive shells only); see
4156 .Sx Emacs editing mode .
4158 Enable gmacs-like command-line editing (interactive shells only).
4159 Currently identical to emacs editing except that transpose\-chars (\*(haT) acts
4160 slightly differently.
4161 .It Fl o Ic ignoreeof
4162 The shell will not (easily) exit when end-of-file is read;
4165 To avoid infinite loops, the shell will exit if
4167 is read 13 times in a row.
4168 .It Fl o Ic inherit\-xtrace
4171 upon entering functions.
4172 This is enabled by default.
4174 Do not kill running jobs with a
4176 signal when a login shell exits.
4177 Currently set by default, but this may
4178 change in the future to be compatible with
4182 doesn't have this option, but does send the
4187 In the original Korn shell, this prevents function definitions from
4188 being stored in the history file.
4189 .It Fl o Ic physical
4196 (i.e. the filesystem's)
4198 directories instead of
4200 directories (i.e. the shell handles
4202 which allows the user to be oblivious of symbolic links to directories).
4204 Note that setting this option does not affect the current value of the
4214 commands above for more details.
4215 .It Fl o Ic pipefail
4216 Make the exit status of a pipeline (before logically complementing) the
4217 rightmost non-zero errorlevel, or zero if all commands exited with zero.
4219 Enable a somewhat more
4222 As a side effect, setting this flag turns off
4224 mode, which can be turned back on manually, and
4232 Automatically enabled if the basename of the shell invocation begins with
4234 and this autodetection feature is compiled in
4236 As a side effect, setting this flag turns off
4238 mode, which can be turned back on manually, and
4244 command-line editing (interactive shells only).
4245 .It Fl o Ic vi\-esccomplete
4246 In vi command-line editing, do command and file name completion when escape
4247 (\*(ha[) is entered in command mode.
4248 .It Fl o Ic vi\-tabcomplete
4249 In vi command-line editing, do command and file name completion when tab (\*(haI)
4250 is entered in insert mode.
4251 This is the default.
4254 In the original Korn shell, unless
4256 was set, the vi command-line mode would let the
4258 driver do the work until ESC (\*(ha[) was entered.
4260 is always in viraw mode.
4263 These options can also be used upon invocation of the shell.
4265 options (with single letter names) can be found in the parameter
4268 with no option name will list all the options and whether each is on or off;
4270 will print the long names of all options that are currently on.
4272 Remaining arguments, if any, are positional parameters and are assigned, in
4273 order, to the positional parameters (i.e. $1, $2, etc.).
4276 and there are no remaining arguments, all positional parameters are cleared.
4277 If no options or arguments are given, the values of all names are printed.
4278 For unknown historical reasons, a lone
4280 option is treated specially \*(en it clears both the
4286 .It Ic shift Op Ar number
4287 The positional parameters
4297 .It Ic sleep Ar seconds
4298 Suspends execution for a minimum of the
4300 specified as positive decimal value with an optional fractional part.
4301 Signal delivery may continue execution earlier.
4303 .It Ic source Ar file Op Ar arg ...
4305 .Ic \&. Po Do dot Dc Pc ,
4306 except that the current working directory is appended to the
4316 this is implemented as a shell alias instead of a builtin.
4318 .It Ic test Ar expression
4319 .It Ic \&[ Ar expression Ic \&]
4323 and returns zero status if true, 1 if false, or greater than 1 if there
4325 It is normally used as the condition command of
4330 Symbolic links are followed for all
4337 The following basic expressions are available:
4344 is a block special device.
4347 is a character special device.
4359 group is the shell's effective group ID.
4362 mode has the setgid bit set.
4365 is a context dependent directory (only useful on HP-UX).
4379 owner is the shell's effective user ID.
4385 command above for a list of options).
4386 As a non-standard extension, if the option starts with a
4388 the test is negated; the test always fails if
4390 doesn't exist (so [ \-o foo \-o \-o !foo ] returns true if and only if option
4393 The same can be achieved with [ \-o ?foo ] like in
4397 can also be the short flag led by either
4401 .Pq no logical negation ,
4414 exists and is readable.
4418 .Xr unix 4 Ns -domain
4431 mode has the setuid bit set.
4434 exists and is writable.
4437 exists and is executable.
4438 .It Ar file1 Fl nt Ar file2
4447 .It Ar file1 Fl ot Ar file2
4456 .It Ar file1 Fl ef Ar file2
4462 has non-zero length.
4469 .It Ar string No = Ar string
4471 .It Ar string No == Ar string
4473 .It Ar string No \*(Gt Ar string
4474 First string operand is greater than second string operand.
4475 .It Ar string No \*(Lt Ar string
4476 First string operand is less than second string operand.
4477 .It Ar string No != Ar string
4478 Strings are not equal.
4479 .It Ar number Fl eq Ar number
4480 Numbers compare equal.
4481 .It Ar number Fl ne Ar number
4482 Numbers compare not equal.
4483 .It Ar number Fl ge Ar number
4484 Numbers compare greater than or equal.
4485 .It Ar number Fl gt Ar number
4486 Numbers compare greater than.
4487 .It Ar number Fl le Ar number
4488 Numbers compare less than or equal.
4489 .It Ar number Fl \< Ar number
4490 Numbers compare less than.
4493 The above basic expressions, in which unary operators have precedence over
4494 binary operators, may be combined with the following operators (listed in
4495 increasing order of precedence):
4496 .Bd -literal -offset indent
4497 expr \-o expr Logical OR.
4498 expr \-a expr Logical AND.
4503 Note that a number actually may be an arithmetic expression, such as
4504 a mathematical term or the name of an integer variable:
4505 .Bd -literal -offset indent
4506 x=1; [ "x" \-eq 1 ] evaluates to true
4509 Note that some special rules are applied (courtesy of
4511 ) if the number of arguments to
4513 or inside the brackets
4515 is less than five: if leading
4517 arguments can be stripped such that only one to three arguments remain,
4518 then the lowered comparison is executed; (thanks to XSI) parentheses
4520 lower four- and three-argument forms to two- and one-argument forms,
4521 respectively; three-argument forms ultimately prefer binary operations,
4522 followed by negation and parenthesis lowering; two- and four-argument forms
4523 prefer negation followed by parenthesis; the one-argument form always implies
4527 A common mistake is to use
4528 .Dq if \&[ $foo = bar \&]
4529 which fails if parameter
4533 or unset, if it has embedded spaces (i.e.\&
4535 octets), or if it is a unary operator like
4540 .Dq if \&[ x\&"$foo\&" = x"bar" \&]
4541 instead, or the double-bracket operator
4542 .Dq if \&[[ $foo = bar \&]]
4543 or, to avoid pattern matching (see
4546 .Dq if \&[[ $foo = \&"$bar" \&]]
4550 construct is not only more secure to use but also often faster.
4559 is given, the times used to execute the pipeline are reported.
4561 is given, then the user and system time used by the shell itself, and all the
4562 commands it has run since it was started, are reported.
4563 The times reported are the real time (elapsed time from start to finish),
4564 the user CPU time (time spent running in user mode), and the system CPU time
4565 (time spent running in kernel mode).
4566 Times are reported to standard error; the format of the output is:
4568 .Dl "0m0.00s real 0m0.00s user 0m0.00s system"
4572 option is given the output is slightly longer:
4573 .Bd -literal -offset indent
4579 It is an error to specify the
4583 is a simple command.
4585 Simple redirections of standard error do not affect the output of the
4589 .Dl $ time sleep 1 2\*(Gtafile
4590 .Dl $ { time sleep 1; } 2\*(Gtafile
4592 Times for the first command do not go to
4594 but those of the second command do.
4597 Print the accumulated user and system times used both by the shell
4598 and by processes that the shell started which have exited.
4599 The format of the output is:
4600 .Bd -literal -offset indent
4605 .It Ic trap Op Ar handler signal ...
4606 Sets a trap handler that is to be executed when any of the specified signals are
4611 string, indicating the signals are to be ignored, a minus sign
4613 indicating that the default action is to be taken for the signals (see
4615 or a string containing shell commands to be evaluated and executed at the first
4616 opportunity (i.e. when the current command completes, or before printing the
4619 prompt) after receipt of one of the signals.
4621 is the name of a signal (e.g.\&
4625 or the number of the signal (see the
4629 There are two special signals:
4631 (also known as 0) which is executed when the shell is about to exit, and
4633 which is executed after an error occurs (an error is something that would cause
4634 the shell to exit if the
4638 option were set \*(en see the
4642 handlers are executed in the environment of the last executed command.
4644 that for non-interactive shells, the trap handler cannot be changed for signals
4645 that were ignored when the shell started.
4649 lists, as a series of
4651 commands, the current state of the traps that have been set since the shell
4653 Note that the output of
4655 cannot be usefully piped to another process (an artifact of the fact that
4656 traps are cleared when subprocesses are created).
4658 The original Korn shell's
4660 trap and the handling of
4664 traps in functions are not yet implemented.
4667 A command that exits with a zero value.
4671 .Oo Op Ic +\-alpnrtUux
4676 .No \*(Ba Fl f Op Fl tux Oc
4678 .Op Ns = Ns Ar value
4683 .Oo Op Ic +\-alpnrtUux
4684 .Op Fl LRZ Ns Op Ar n
4686 .No \*(Ba Fl f Op Fl tux Oc
4688 .Op Ns = Ns Ar value
4691 Display or set parameter attributes.
4694 arguments, parameter attributes are displayed; if no options are used, the
4695 current attributes of all parameters are printed as
4697 commands; if an option is given (or
4699 with no option letter), all parameters and their values with the specified
4700 attributes are printed; if options are introduced with
4702 parameter values are not printed.
4706 arguments are given, the attributes of the named parameters are set
4710 Values for parameters may optionally be specified.
4713 the change affects the entire array, and no value may be specified.
4717 is used inside a function, any parameters specified are localised.
4718 This is not done by the otherwise identical
4725 equivalent to other programming languages' as it does not allow a
4726 function called from another function to access a parameter at truly
4727 global scope, but only prevents putting an accessed one into local scope.
4733 operates on the attributes of functions.
4734 As with parameters, if no
4736 arguments are given,
4737 functions are listed with their values (i.e. definitions) unless
4738 options are introduced with
4740 in which case only the function names are reported.
4743 Indexed array attribute.
4746 Display or set functions and their attributes, instead of parameters.
4750 specifies the base to use when displaying the integer (if not specified, the
4751 base given in the first assignment is used).
4752 Parameters with this attribute may
4753 be assigned values containing arithmetic expressions.
4755 Left justify attribute.
4757 specifies the field width.
4760 is not specified, the current width of a parameter (or the width of its first
4761 assigned value) is used.
4762 Leading whitespace (and zeros, if used with the
4764 option) is stripped.
4765 If necessary, values are either truncated or space padded
4766 to fit the field width.
4768 Lower case attribute.
4769 All upper case characters in values are converted to lower case.
4770 (In the original Korn shell, this parameter meant
4776 Create a bound variable (name reference): any access to the variable
4778 will access the variable
4780 in the current scope (this is different from
4789 is lazily evaluated at the time
4792 This can be used by functions to access variables whose names are
4793 passed as parametres, instead of using
4798 commands that can be used to re-create the attributes and values of
4801 Right justify attribute.
4803 specifies the field width.
4806 is not specified, the current width of a parameter (or the width of its first
4807 assigned value) is used.
4808 Trailing whitespace is stripped.
4809 If necessary, values are either stripped of leading characters or space
4810 padded to make them fit the field width.
4812 Read-only attribute.
4813 Parameters with this attribute may not be assigned to or unset.
4814 Once this attribute is set, it cannot be turned off.
4817 Has no meaning to the shell; provided for application use.
4821 is the trace attribute.
4822 When functions with the trace attribute are executed, the
4825 shell option is temporarily turned on.
4827 Unsigned integer attribute.
4828 Integers are printed as unsigned values (combine with the
4831 This option is not in the original Korn shell.
4833 Upper case attribute.
4834 All lower case characters in values are converted to upper case.
4835 (In the original Korn shell, this parameter meant
4836 .Dq unsigned integer
4839 option which meant upper case letters would never be used for bases greater
4847 is the undefined attribute.
4850 above for the implications of this.
4853 Parameters (or functions) are placed in the environment of
4854 any executed commands.
4855 Exported functions are not yet implemented.
4857 Zero fill attribute.
4858 If not combined with
4862 except zero padding is used instead of space padding.
4863 For integers, the number instead of the base is padded.
4876 options are changed, all others from this set are cleared,
4877 unless they are also given on the same command line.
4881 .Op Fl aBCcdefHiLlMmnOPpqrSsTtVvw
4884 Display or set process limits.
4885 If no options are used, the file size limit
4889 if specified, may be either an arithmetic expression or the word
4891 The limits affect the shell and any processes created by the shell after a
4893 Note that some systems may not allow limits to be increased
4895 Also note that the types of limits available are system
4896 dependent \*(en some systems have only the
4901 Display all limits; unless
4903 is used, soft limits are displayed.
4905 Set the socket buffer size to
4909 Set the number of cached threads to
4912 Impose a size limit of
4914 blocks on the size of core dumps.
4916 Impose a size limit of
4918 kibibytes on the size of the data area.
4920 Set the maximum niceness to
4923 Impose a size limit of
4925 blocks on files written by the shell and its child processes (files of any
4928 Set the hard limit only (the default is to set both hard and soft limits).
4930 Set the number of pending signals to
4933 Control flocks; documentation is missing.
4937 kibibytes on the amount of locked (wired) physical memory.
4939 Set the AIO locked memory to
4945 kibibytes on the amount of physical memory used.
4949 file descriptors that can be open at once.
4951 Set the number of AIO operations to
4954 Limit the number of threads per process to
4959 processes that can be run by the user at any one time.
4967 Set the maximum real-time priority to
4970 Set the soft limit only (the default is to set both hard and soft limits).
4972 Impose a size limit of
4974 kibibytes on the size of the stack area.
4976 Impose a time limit of
4978 real seconds to be used by each process.
4980 Impose a time limit of
4982 CPU seconds spent in user mode to be used by each process.
4984 Set the number of vnode monitors on Haiku to
4989 kibibytes on the amount of virtual memory (address space) used.
4993 kibibytes on the amount of swap space used.
4998 is concerned, a block is 512 bytes.
5005 Display or set the file permission creation mask, or umask (see
5009 option is used, the mask displayed or set is symbolic; otherwise, it is an
5012 Symbolic masks are like those used by
5014 When used, they describe what permissions may be made available (as opposed to
5015 octal masks in which a set bit means the corresponding bit is to be cleared).
5018 sets the mask so files will not be readable, writable, or executable by
5020 and is equivalent (on most systems) to the octal mask
5028 The aliases for the given names are removed.
5031 option is used, all aliases are removed.
5036 options are used, the indicated operations are carried out on tracked or
5037 directory aliases, respectively.
5044 Unset the named parameters
5052 .Ar parameter Ns \&[*] ,
5053 attributes are kept, only values are unset.
5055 The exit status is non-zero if any of the parameters have the read-only
5056 attribute set, zero otherwise.
5058 .It Ic wait Op Ar job ...
5059 Wait for the specified job(s) to finish.
5062 is that of the last specified job; if the last job is killed by a signal, the
5063 exit status is 128 + the number of the signal (see
5064 .Ic kill \-l Ar exit-status
5065 above); if the last specified job can't be found (because it never existed, or
5066 had already finished), the exit status of
5071 below for the format of
5074 will return if a signal for which a trap has been set is received, or if a
5081 If no jobs are specified,
5083 waits for all currently running jobs (if any) to finish and exits with a zero
5085 If job monitoring is enabled, the completion status of jobs is printed
5086 (this is not the case when jobs are explicitly specified).
5095 the type of command is listed (reserved word, built-in, alias,
5096 function, tracked alias, or executable).
5099 option is used, a path search is performed even if
5101 is a reserved word, alias, etc.
5110 will find reserved words and won't print aliases as alias commands.
5121 option does not affect the search path used, as it does for
5123 If the type of one or more of the names could not be determined, the exit
5127 Job control refers to the shell's ability to monitor and control jobs which
5128 are processes or groups of processes created for commands or pipelines.
5129 At a minimum, the shell keeps track of the status of the background (i.e.\&
5130 asynchronous) jobs that currently exist; this information can be displayed
5134 If job control is fully enabled (using
5137 .Ic set \-o monitor ) ,
5138 as it is for interactive shells, the processes of a job are placed in their
5140 Foreground jobs can be stopped by typing the suspend
5141 character from the terminal (normally \*(haZ), jobs can be restarted in either the
5142 foreground or background using the
5146 commands, and the state of the terminal is saved or restored when a foreground
5147 job is stopped or restarted, respectively.
5149 Note that only commands that create processes (e.g. asynchronous commands,
5150 subshell commands, and non-built-in, non-function commands) can be stopped;
5155 When a job is created, it is assigned a job number.
5156 For interactive shells, this number is printed inside
5158 followed by the process IDs of the processes in the job when an asynchronous
5160 A job may be referred to in the
5167 commands either by the process ID of the last process in the command pipeline
5170 parameter) or by prefixing the job number with a percent
5173 Other percent sequences can also be used to refer to jobs:
5174 .Bl -tag -width "%+ x %% x %XX"
5175 .It %+ \*(Ba %% \*(Ba %
5176 The most recently stopped job, or, if there are no stopped jobs, the oldest
5179 The job that would be the
5181 job if the latter did not exist.
5183 The job with job number
5186 The job with its command containing the string
5188 (an error occurs if multiple jobs are matched).
5190 The job with its command starting with the string
5192 (an error occurs if multiple jobs are matched).
5195 When a job changes state (e.g. a background job finishes or foreground job is
5196 stopped), the shell prints the following status information:
5198 .D1 [ Ns Ar number ] Ar flag status command
5201 .Bl -tag -width "command"
5203 is the job number of the job;
5209 character if the job is the
5213 job, respectively, or space if it is neither;
5215 indicates the current state of the job and can be:
5216 .Bl -tag -width "RunningXX"
5217 .It Done Op Ar number
5220 is the exit status of the job which is omitted if the status is zero.
5222 The job has neither stopped nor exited (note that running does not necessarily
5223 mean consuming CPU time \*(en
5224 the process could be blocked waiting for some event).
5225 .It Stopped Op Ar signal
5226 The job was stopped by the indicated
5228 (if no signal is given, the job was stopped by
5230 .It Ar signal-description Op Dq core dumped
5231 The job was killed by a signal (e.g. memory fault, hangup); use
5233 for a list of signal descriptions.
5236 message indicates the process created a core file.
5239 is the command that created the process.
5240 If there are multiple processes in
5241 the job, each process will have a line showing its
5245 if it is different from the status of the previous process.
5248 When an attempt is made to exit the shell while there are jobs in the stopped
5249 state, the shell warns the user that there are stopped jobs and does not exit.
5250 If another attempt is immediately made to exit the shell, the stopped jobs are
5253 signal and the shell exits.
5256 option is not set and there are running jobs when an attempt is made to exit
5257 a login shell, the shell warns the user and does not exit.
5259 is immediately made to exit the shell, the running jobs are sent a
5261 signal and the shell exits.
5262 .Ss Interactive input line editing
5263 The shell supports three modes of reading command lines from a
5265 in an interactive session, controlled by the
5270 options (at most one of these can be set at once).
5273 Editing modes can be set explicitly using the
5276 If none of these options are enabled,
5277 the shell simply reads lines using the normal
5284 option is set, the shell allows emacs-like editing of the command; similarly,
5287 option is set, the shell allows vi-like editing of the command.
5288 These modes are described in detail in the following sections.
5290 In these editing modes, if a line is longer than the screen width (see the
5298 character is displayed in the last column indicating that there are more
5299 characters after, before and after, or before the current position,
5301 The line is scrolled horizontally as necessary.
5303 Completed lines are pushed into the history, unless they begin with an
5304 IFS octet or IFS white space, or are the same as the previous line.
5305 .Ss Emacs editing mode
5308 option is set, interactive input line editing is enabled.
5309 Warning: This mode is
5310 slightly different from the emacs mode in the original Korn shell.
5311 In this mode, various editing commands
5312 (typically bound to one or more control characters) cause immediate actions
5313 without waiting for a newline.
5314 Several editing commands are bound to particular
5315 control characters when the shell is invoked; these bindings can be changed
5320 The following is a list of available editing commands.
5321 Each description starts with the name of the command,
5322 suffixed with a colon;
5325 (if the command can be prefixed with a count); and any keys the command is
5326 bound to by default, written using caret notation
5327 e.g. the ASCII ESC character is written as \*(ha[.
5328 These control sequences are not case sensitive.
5329 A count prefix for a command is entered using the sequence
5330 .Pf \*(ha[ Ns Ar n ,
5333 is a sequence of 1 or more digits.
5334 Unless otherwise specified, if a count is
5335 omitted, it defaults to 1.
5337 Note that editing command names are used only with the
5340 Furthermore, many editing commands are useful only on terminals with
5342 The default bindings were chosen to resemble corresponding
5349 reasonable substitutes and override the default bindings.
5351 .It abort: \*(haC, \*(haG
5352 Abort the current command, empty the line buffer and
5353 set the exit state to interrupted.
5354 .It auto\-insert: Op Ar n
5355 Simply causes the character to appear as literal input.
5356 Most ordinary characters are bound to this.
5357 .It Xo backward\-char:
5359 .No \*(haB , \*(haXD , ANSI-CurLeft
5361 Moves the cursor backward
5364 .It Xo backward\-word:
5366 .No \*(ha[b , ANSI-Ctrl-CurLeft , ANSI-Alt-CurLeft
5368 Moves the cursor backward to the beginning of the word; words consist of
5369 alphanumerics, underscore
5374 .It beginning\-of\-history: \*(ha[\*(Lt
5375 Moves to the beginning of the history.
5376 .It beginning\-of\-line: \*(haA, ANSI-Home
5377 Moves the cursor to the beginning of the edited input line.
5378 .It Xo capitalise\-word:
5380 .No \*(ha[C , \*(ha[c
5382 Uppercase the first character in the next
5384 words, leaving the cursor past the end of the last word.
5385 .It clear\-screen: \*(ha[\*(haL
5386 Prints a compile-time configurable sequence to clear the screen and home
5387 the cursor, redraws the entire prompt and the currently edited input line.
5388 The default sequence works for almost all standard terminals.
5389 .It comment: \*(ha[#
5390 If the current line does not begin with a comment character, one is added at
5391 the beginning of the line and the line is entered (as if return had been
5392 pressed); otherwise, the existing comment characters are removed and the cursor
5393 is placed at the beginning of the line.
5394 .It complete: \*(ha[\*(ha[
5395 Automatically completes as much as is unique of the command name or the file
5396 name containing the cursor.
5397 If the entire remaining command or file name is
5398 unique, a space is printed after its completion, unless it is a directory name
5402 If there is no command or file name with the current partial word
5403 as its prefix, a bell character is output (usually causing a beep to be
5405 .It complete\-command: \*(haX\*(ha[
5406 Automatically completes as much as is unique of the command name having the
5407 partial word up to the cursor as its prefix, as in the
5410 .It complete\-file: \*(ha[\*(haX
5411 Automatically completes as much as is unique of the file name having the
5412 partial word up to the cursor as its prefix, as in the
5414 command described above.
5415 .It complete\-list: \*(haI, \*(ha[=
5416 Complete as much as is possible of the current word,
5417 and list the possible completions for it.
5418 If only one completion is possible,
5422 Note that \*(haI is usually generated by the TAB (tabulator) key.
5423 .It Xo delete\-char\-backward:
5425 .No ERASE , \*(ha? , \*(haH
5429 characters before the cursor.
5430 .It Xo delete\-char\-forward:
5436 characters after the cursor.
5437 .It Xo delete\-word\-backward:
5439 .No WERASE , \*(ha[\*(ha? , \*(ha[\*(haH , \*(ha[h
5443 words before the cursor.
5444 .It Xo delete\-word\-forward:
5448 Deletes characters after the cursor up to the end of
5451 .It Xo down\-history:
5453 .No \*(haN , \*(haXB , ANSI-CurDown
5455 Scrolls the history buffer forward
5458 Each input line originally starts just after the last entry
5459 in the history buffer, so
5461 is not useful until either
5462 .Ic search\-history ,
5463 .Ic search\-history\-up
5467 .It Xo downcase\-word:
5469 .No \*(ha[L , \*(ha[l
5480 or the current line, if not specified, interactively.
5481 The actual command executed is
5482 .Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n .
5483 .It end\-of\-history: \*(ha[\*(Gt
5484 Moves to the end of the history.
5485 .It end\-of\-line: \*(haE, ANSI-End
5486 Moves the cursor to the end of the input line.
5488 Acts as an end-of-file; this is useful because edit-mode input disables
5489 normal terminal input canonicalization.
5490 .It Xo eot\-or\-delete:
5496 if alone on a line; otherwise acts as
5497 .Ic delete\-char\-forward .
5498 .It error: (not bound)
5499 Error (ring the bell).
5500 .It exchange\-point\-and\-mark: \*(haX\*(haX
5501 Places the cursor where the mark is and sets the mark to where the cursor was.
5502 .It expand\-file: \*(ha[*
5505 to the current word and replaces the word with the result of performing file
5506 globbing on the word.
5507 If no files match the pattern, the bell is rung.
5508 .It Xo forward\-char:
5510 .No \*(haF , \*(haXC , ANSI-CurRight
5512 Moves the cursor forward
5515 .It Xo forward\-word:
5517 .No \*(ha[f , ANSI-Ctrl-CurRight , ANSI-Alt-CurRight
5519 Moves the cursor forward to the end of the
5522 .It Xo goto\-history:
5526 Goes to history number
5528 .It kill\-line: KILL
5529 Deletes the entire input line.
5530 .It kill\-region: \*(haW
5531 Deletes the input between the cursor and the mark.
5532 .It Xo kill\-to\-eol:
5536 Deletes the input from the cursor to the end of the line if
5538 is not specified; otherwise deletes characters between the cursor and column
5541 Prints a sorted, columnated list of command names or file names (if any) that
5542 can complete the partial word containing the cursor.
5543 Directory names have
5546 .It list\-command: \*(haX?
5547 Prints a sorted, columnated list of command names (if any) that can complete
5548 the partial word containing the cursor.
5549 .It list\-file: \*(haX\*(haY
5550 Prints a sorted, columnated list of file names (if any) that can complete the
5551 partial word containing the cursor.
5552 File type indicators are appended as described under
5555 .It newline: \*(haJ , \*(haM
5556 Causes the current input line to be processed by the shell.
5557 The current cursor position may be anywhere on the line.
5558 .It newline\-and\-next: \*(haO
5559 Causes the current input line to be processed by the shell, and the next line
5560 from history becomes the current line.
5561 This is only useful after an
5565 .Ic search\-history\-up .
5568 .It prefix\-1: \*(ha[
5569 Introduces a 2-character command sequence.
5570 .It prefix\-2: \*(haX , \*(ha[[ , \*(ha[O
5571 Introduces a 2-character command sequence.
5572 .It Xo prev\-hist\-word:
5574 .No \*(ha[. , \*(ha[_
5576 The last word, or, if given, the
5578 word (zero-based) of the previous (on repeated execution, second-last,
5579 third-last, etc.) command is inserted at the cursor.
5580 Use of this editing command trashes the mark.
5581 .It quote: \*(ha\*(ha , \*(haV
5582 The following character is taken literally rather than as an editing command.
5584 Reprints the last line of the prompt string and the current input line
5586 .It Xo search\-character\-backward:
5590 Search backward in the current line for the
5592 occurrence of the next character typed.
5593 .It Xo search\-character\-forward:
5597 Search forward in the current line for the
5599 occurrence of the next character typed.
5600 .It search\-history: \*(haR
5601 Enter incremental search mode.
5602 The internal history list is searched
5603 backwards for commands matching the input.
5606 in the search string anchors the search.
5607 The escape key will leave search mode.
5608 Other commands, including sequences of escape as
5614 key will be executed after leaving search mode.
5617 command will restore the input line before search started.
5620 commands continue searching backward to the next previous occurrence of the
5622 The history buffer retains only a finite number of lines; the oldest
5623 are discarded as necessary.
5624 .It search\-history\-up: ANSI-PgUp
5625 Search backwards through the history buffer for commands whose beginning match
5626 the portion of the input line before the cursor.
5627 When used on an empty line, this has the same effect as
5629 .It search\-history\-down: ANSI-PgDn
5630 Search forwards through the history buffer for commands whose beginning match
5631 the portion of the input line before the cursor.
5632 When used on an empty line, this has the same effect as
5634 This is only useful after an
5638 .Ic search\-history\-up .
5639 .It set\-mark\-command: \*(ha[ Ns Aq space
5640 Set the mark at the cursor position.
5641 .It transpose\-chars: \*(haT
5642 If at the end of line, or if the
5644 option is set, this exchanges the two previous characters; otherwise, it
5645 exchanges the previous and current characters and moves the cursor one
5646 character to the right.
5649 .No \*(haP , \*(haXA , ANSI-CurUp
5651 Scrolls the history buffer backward
5654 .It Xo upcase\-word:
5656 .No \*(ha[U , \*(ha[u
5661 .It version: \*(ha[\*(haV
5662 Display the version of
5664 The current edit buffer is restored as soon as a key is pressed.
5665 The restoring keypress is processed, unless it is a space.
5667 Inserts the most recently killed text string at the current cursor position.
5668 .It yank\-pop: \*(ha[y
5671 replaces the inserted text string with the next previously killed text string.
5675 The vi command-line editing mode is orphaned, yet still functional.
5677 The vi command-line editor in
5679 has basically the same commands as the
5681 editor with the following exceptions:
5684 You start out in insert mode.
5686 There are file name and command completion commands:
5687 =, \e, *, \*(haX, \*(haE, \*(haF, and, optionally,
5694 command is different (in
5696 it is the last argument command; in
5698 it goes to the start of the current line).
5704 commands move in the opposite direction to the
5708 Commands which don't make sense in a single line editor are not available
5709 (e.g. screen movement commands and
5718 there are two modes:
5723 In insert mode, most characters are simply put in the buffer at the
5724 current cursor position as they are typed; however, some characters are
5726 In particular, the following characters are taken from current
5731 and have their usual meaning (normal values are in parentheses): kill (\*(haU),
5732 erase (\*(ha?), werase (\*(haW), eof (\*(haD), intr (\*(haC), and quit (\*(ha\e).
5734 the above, the following characters are also treated specially in insert mode:
5735 .Bl -tag -width XJXXXXM
5737 Command and file name enumeration (see below).
5739 Command and file name completion (see below).
5740 If used twice in a row, the
5741 list of possible completions is displayed; if used a third time, the completion
5744 Erases previous character.
5745 .It \*(haJ \*(Ba \*(haM
5747 The current line is read, parsed, and executed by the shell.
5750 The next character typed is not treated specially (can be used
5751 to insert the characters being described here).
5753 Command and file name expansion (see below).
5755 Puts the editor in command mode (see below).
5757 Optional file name and command completion (see
5759 above), enabled with
5760 .Ic set \-o vi\-tabcomplete .
5763 In command mode, each character is interpreted as a command.
5765 don't correspond to commands, are illegal combinations of commands, or are
5766 commands that can't be carried out, all cause beeps.
5767 In the following command descriptions, an
5769 indicates the command may be prefixed by a number (e.g.\&
5771 moves right 10 characters); if no number prefix is used,
5773 is assumed to be 1 unless otherwise specified.
5775 .Dq current position
5776 refers to the position between the cursor and the character preceding the
5780 is a sequence of letters, digits, and underscore characters or a sequence of
5781 non-letter, non-digit, non-underscore, and non-whitespace characters (e.g.\&
5783 contains two words) and a
5785 is a sequence of non-whitespace characters.
5791 The following commands are not in, or are different from, the normal vi file
5797 Insert a space followed by the
5799 big-word from the last command in the history at the current position and enter
5802 is not specified, the last word is inserted.
5804 Insert the comment character
5806 at the start of the current line and return the line to the shell (equivalent
5816 is not specified, it goes to the most recent remembered line.
5826 is not specified, the current line is edited.
5827 The actual command executed is
5828 .Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n .
5830 Command or file name expansion is applied to the current big-word (with an
5833 if the word contains no file globbing characters) \*(en the big-word is replaced
5834 with the resulting words.
5835 If the current big-word is the first on the line
5836 or follows one of the characters
5843 and does not contain a slash
5845 then command expansion is done; otherwise file name expansion is done.
5846 Command expansion will match the big-word against all aliases, functions, and
5847 built-in commands as well as any executable files found by searching the
5851 File name expansion matches the big-word against the files in the
5853 After expansion, the cursor is placed just past the last
5854 word and the editor is in insert mode.
5857 .Oo Ar n Oc Ns \*(haF ,
5858 .Oo Ar n Oc Ns Aq tab ,
5860 .Oo Ar n Oc Ns Aq esc
5862 Command/file name completion.
5863 Replace the current big-word with the
5864 longest unique match obtained after performing command and file name expansion.
5866 is only recognised if the
5868 option is set, while
5870 is only recognised if the
5878 possible completion is selected (as reported by the command/file name
5879 enumeration command).
5881 Command/file name enumeration.
5882 List all the commands or files that match the current big-word.
5884 Display the version of
5886 The current edit buffer is restored as soon as a key is pressed.
5887 The restoring keypress is ignored.
5890 Execute the commands found in the alias
5894 Intra-line movement commands:
5897 .Oo Ar n Oc Ns h and
5898 .Oo Ar n Oc Ns \*(haH
5904 .Oo Ar n Oc Ns l and
5905 .Oo Ar n Oc Ns Aq space
5913 Move to the first non-whitespace character.
5915 .Oo Ar n Oc Ns \*(Ba
5920 Move to the last character.
5936 Move forward to the end of the word,
5942 Move forward to the end of the big-word,
5959 The editor looks forward for the nearest parenthesis, bracket, or
5960 brace and then moves the cursor to the matching parenthesis, bracket, or brace.
5962 .Oo Ar n Oc Ns f Ns Ar c
5966 occurrence of the character
5969 .Oo Ar n Oc Ns F Ns Ar c
5971 Move backward to the
5973 occurrence of the character
5976 .Oo Ar n Oc Ns t Ns Ar c
5978 Move forward to just before the
5980 occurrence of the character
5983 .Oo Ar n Oc Ns T Ns Ar c
5985 Move backward to just before the
5987 occurrence of the character
6004 command, but moves in the opposite direction.
6007 Inter-line movement commands:
6013 .Oo Ar n Oc Ns \*(haN
6017 next line in the history.
6022 .Oo Ar n Oc Ns \*(haP
6026 previous line in the history.
6034 is not specified, the number of the first remembered line is used.
6042 is not specified, it goes to the most recent remembered line.
6044 .Oo Ar n Oc Ns / Ns Ar string
6046 Search backward through the history for the
6054 the remainder of the string must appear at the start of the history line for
6057 .Oo Ar n Oc Ns \&? Ns Ar string
6061 except it searches forward through the history.
6067 occurrence of the last search string;
6068 the direction of the search is the same as the last search.
6074 occurrence of the last search string;
6075 the direction of the search is the opposite of the last search.
6077 Take the characters from the beginning of the line to the current
6078 cursor position as search string and do a backwards history search
6079 for lines beginning with this string; keep the cursor position.
6080 This works only in insert mode and keeps it enabled.
6090 times; goes into insert mode just after the current position.
6092 only replicated if command mode is re-entered i.e.\&
6100 except it appends at the end of the line.
6106 times; goes into insert mode at the current position.
6107 The insertion is only
6108 replicated if command mode is re-entered i.e.\&
6116 except the insertion is done just before the first non-blank character.
6122 characters (i.e. delete the characters and go into insert mode).
6124 Substitute whole line.
6125 All characters from the first non-blank character to the
6126 end of the line are deleted and insert mode is entered.
6128 .Oo Ar n Oc Ns c Ns Ar move-cmd
6130 Change from the current position to the position resulting from
6132 (i.e. delete the indicated region and go into insert mode); if
6136 the line starting from the first non-blank character is changed.
6138 Change from the current position to the end of the line (i.e. delete to the
6139 end of the line and go into insert mode).
6153 Delete to the end of the line.
6155 .Oo Ar n Oc Ns d Ns Ar move-cmd
6157 Delete from the current position to the position resulting from
6158 .Ar n move-cmd Ns s ;
6160 is a movement command (see above) or
6162 in which case the current line is deleted.
6164 .Oo Ar n Oc Ns r Ns Ar c
6168 characters with the character
6174 Enter insert mode but overwrite existing characters instead of
6175 inserting before existing characters.
6176 The replacement is repeated
6180 .Oo Ar n Oc Ns \*(TI
6182 Change the case of the next
6186 .Oo Ar n Oc Ns y Ns Ar move-cmd
6188 Yank from the current position to the position resulting from
6190 into the yank buffer; if
6194 the whole line is yanked.
6196 Yank from the current position to the end of the line.
6200 Paste the contents of the yank buffer just after the current position,
6208 except the buffer is pasted at the current position.
6211 Miscellaneous vi commands
6213 .It \*(haJ and \*(haM
6214 The current line is read, parsed, and executed by the shell.
6215 .It \*(haL and \*(haR
6216 Redraw the current line.
6220 Redo the last edit command
6224 Undo the last edit command.
6226 Undo all changes that have been made to the current line.
6227 .It Ar intr No and Ar quit
6228 The interrupt and quit terminal characters cause the current line to be
6229 deleted and a new prompt to be printed.
6232 .Bl -tag -width XetcXsuid_profile -compact
6233 .It Pa \*(TI/.mkshrc
6234 User mkshrc profile (non-privileged interactive shells); see
6236 The location can be changed at compile time (for embedded systems);
6237 AOSP Android builds use
6238 .Pa /system/etc/mkshrc .
6239 .It Pa \*(TI/.profile
6240 User profile (non-privileged login shells); see
6242 near the top of this manual.
6244 System profile (login shells); see
6248 .It Pa /etc/suid_profile
6249 Suid profile (privileged shells); see
6255 contains the system and suid profile.
6286 .Pa http://docsrv.sco.com:507/en/man/html.C/sh.C.html
6288 .Pa https://www.mirbsd.org/ksh\-chan.htm
6291 .%B "The KornShell Command and Programming Language"
6293 .%I "Prentice Hall PTR"
6294 .%P "xvi\ +\ 356 pages"
6295 .%O "ISBN 978\-0\-13\-516972\-8 (0\-13\-516972\-0)"
6298 .%A Morris I. Bolsky
6300 .%B "The New KornShell Command and Programming Language (2nd Edition)"
6302 .%I "Prentice Hall PTR"
6303 .%P "xvi\ +\ 400 pages"
6304 .%O "ISBN 978\-0\-13\-182700\-4 (0\-13\-182700\-6)"
6307 .%A Stephen G. Kochan
6309 .%B "\\*(tNUNIX\\*(sP Shell Programming"
6310 .%V "Revised Edition"
6313 .%P "xi\ +\ 490 pages"
6314 .%O "ISBN 978\-0\-672\-48448\-3 (0\-672\-48448\-X)"
6318 .%B "\\*(tNIEEE\\*(sP Standard for Information Technology \*(en Portable Operating System Interface (POSIX)"
6319 .%V "Part 2: Shell and Utilities"
6322 .%P "xvii\ +\ 1195 pages"
6323 .%O "ISBN 978\-1\-55937\-255\-8 (1\-55937\-255\-9)"
6327 .%B "Learning the Korn Shell"
6331 .%O "ISBN 978\-1\-56592\-054\-5 (1\-56592\-054\-6)"
6336 .%B "Learning the Korn Shell, Second Edition"
6340 .%O "ISBN 978\-0\-596\-00195\-7 (0\-596\-00195\-9)"
6344 .%B "KornShell Programming Tutorial"
6346 .%I "Addison-Wesley Professional"
6347 .%P "xxi\ +\ 324 pages"
6348 .%O "ISBN 978\-0\-201\-56324\-5 (0\-201\-56324\-X)"
6351 .Nm "The MirBSD Korn Shell"
6353 .An Thorsten Glaser Aq tg@mirbsd.org
6354 and currently maintained as part of The MirOS Project.
6355 This shell is based upon the Public Domain Korn SHell.
6356 The developer of mksh recognises the efforts of the pdksh authors,
6357 who had dedicated their work into Public Domain, our users, and
6358 all contributors, such as the Debian and OpenBSD projects.
6360 .\" Charles Forsyth, author of the (Public Domain) Bourne Shell clone,
6361 .\" which mksh is derived from, agreed to the following:
6363 .\" In countries where the Public Domain status of the work may not be
6364 .\" valid, its primary author hereby grants a copyright licence to the
6365 .\" general public to deal in the work without restriction and permis-
6366 .\" sion to sublicence derivates under the terms of any (OSI approved)
6367 .\" Open Source licence.
6369 See the documentation, CVS, and web site for details.
6371 The BSD daemon is Copyright \(co Marshall Kirk McKusick.
6372 The complete legalese is at:
6373 .Pa https://www.mirbsd.org/TaC\-mksh.txt
6375 .\" This boils down to: feel free to use mksh.ico as application icon
6376 .\" or shortcut for mksh or mksh/Win32; distro patches are ok (but we
6377 .\" request they amend $KSH_VERSION when modifying mksh). Authors are
6378 .\" Marshall Kirk McKusick (UCB), Rick Collette (ekkoBSD), Thorsten
6379 .\" Glaser, Benny Siegert (MirBSD), Michael Langguth (mksh/Win32).
6381 .\" As far as MirBSD is concerned, the files themselves are free
6382 .\" to modification and distribution under BSD/MirOS Licence, the
6383 .\" restriction on use stems only from trademark law's requirement
6384 .\" to protect it or lose it, which McKusick almost did.
6388 only supports the Unicode BMP (Basic Multilingual Plane).
6391 has a different scope model from
6394 which leads to subtile differences in semantics for identical builtins.
6395 This can cause issues with a
6397 to suddenly point to a local variable by accident; fixing this is hard.
6399 The parts of a pipeline, like below, are executed in subshells.
6400 Thus, variable assignments inside them are not visible in the
6401 surrounding execution environment.
6402 Use co-processes instead.
6403 .Bd -literal -offset indent
6404 foo \*(Ba bar \*(Ba read baz # will not change $baz
6405 foo \*(Ba bar \*(Ba& read \-p baz # will, however, do so
6409 provides a consistent set of 32-bit integer arithmetics, both signed
6410 and unsigned, with defined wraparound and sign of the result of a modulo
6411 operation, even (defying POSIX) on 64-bit systems.
6412 If you require 64-bit integer arithmetics, use
6413 .Nm lksh Pq legacy mksh
6414 instead, but be aware that, in POSIX, it's legal for the OS to make
6415 .Li print $((2147483647 + 1))
6416 delete all files on your system, as it's Undefined Behaviour.
6418 Suspending (using \*(haZ) pipelines like the one below will only suspend
6419 the currently running part of the pipeline; in this example,
6421 is immediately printed on suspension (but not later after an
6423 .Bd -literal -offset indent
6424 $ /bin/sleep 666 && echo fubar
6427 This document attempts to describe
6430 compiled without any options impacting functionality, such as
6434 which, on some systems only, enables
6436 automatically (whose behaviour differs across targets),
6437 for an operating environment supporting all of its advanced needs.
6438 Please report bugs in
6443 .Aq miros\-mksh@mirbsd.org
6448 .Pa irc.freenode.net
6449 .Pq Port 6697 SSL, 6667 unencrypted ,
6451 .Pa https://launchpad.net/mksh
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