361 lines
8.8 KiB
Groff
361 lines
8.8 KiB
Groff
.\" $MirOS: src/bin/mksh/lksh.1,v 1.17 2016/02/11 20:12:09 tg Exp $
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.\"-
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.\" Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015, 2016
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.\" mirabilos <m@mirbsd.org>
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.\"
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.\" Provided that these terms and disclaimer and all copyright notices
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.\" are retained or reproduced in an accompanying document, permission
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.\" is granted to deal in this work without restriction, including un‐
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.\" limited rights to use, publicly perform, distribute, sell, modify,
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.\" merge, give away, or sublicence.
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.\"
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.\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
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.\" the utmost extent permitted by applicable law, neither express nor
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.\" implied; without malicious intent or gross negligence. In no event
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.\" may a licensor, author or contributor be held liable for indirect,
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.\" direct, other damage, loss, or other issues arising in any way out
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.\" of dealing in the work, even if advised of the possibility of such
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.\" damage or existence of a defect, except proven that it results out
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.\" of said person’s immediate fault when using the work as intended.
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.\"-
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.\" Try to make GNU groff and AT&T nroff more compatible
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.\" * ` generates ‘ in gnroff, so use \`
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.\" * ' generates ’ in gnroff, \' generates ´, so use \*(aq
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.\" * - generates ‐ in gnroff, \- generates −, so .tr it to -
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.\" thus use - for hyphens and \- for minus signs and option dashes
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.\" * ~ is size-reduced and placed atop in groff, so use \*(TI
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.\" * ^ is size-reduced and placed atop in groff, so use \*(ha
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.\" * \(en does not work in nroff, so use \*(en
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.\" * <>| are problematic, so redefine and use \*(Lt\*(Gt\*(Ba
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.\" Also make sure to use \& *before* a punctuation char that is to not
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.\" be interpreted as punctuation, and especially with two-letter words
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.\" but also (after) a period that does not end a sentence (“e.g.\&”).
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.\" The section after the "doc" macropackage has been loaded contains
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.\" additional code to convene between the UCB mdoc macropackage (and
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.\" its variant as BSD mdoc in groff) and the GNU mdoc macropackage.
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.\"
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.ie \n(.g \{\
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. if \*[.T]ascii .tr \-\N'45'
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. if \*[.T]latin1 .tr \-\N'45'
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. if \*[.T]utf8 .tr \-\N'45'
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. ds <= \[<=]
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. ds >= \[>=]
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. ds Rq \[rq]
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. ds Lq \[lq]
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. ds sL \(aq
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. ds sR \(aq
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. if \*[.T]utf8 .ds sL `
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. if \*[.T]ps .ds sL `
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. if \*[.T]utf8 .ds sR '
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. if \*[.T]ps .ds sR '
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. ds aq \(aq
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. ds TI \(ti
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. ds ha \(ha
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. ds en \(en
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.\}
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.el \{\
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. ds aq '
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. ds TI ~
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. ds ha ^
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. ds en \(em
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.\}
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.\"
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.\" Implement .Dd with the Mdocdate RCS keyword
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.\"
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.rn Dd xD
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.de Dd
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.ie \\$1$Mdocdate: \{\
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. xD \\$2 \\$3, \\$4
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.\}
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.el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8
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..
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.\"
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.\" .Dd must come before definition of .Mx, because when called
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.\" with -mandoc, it might implement .Mx itself, but we want to
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.\" use our own definition. And .Dd must come *first*, always.
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.\"
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.Dd $Mdocdate: February 11 2016 $
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.\"
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.\" Check which macro package we use, and do other -mdoc setup.
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.\"
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.ie \n(.g \{\
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. if \*[.T]utf8 .tr \[la]\*(Lt
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. if \*[.T]utf8 .tr \[ra]\*(Gt
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. ie d volume-ds-1 .ds tT gnu
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. el .ds tT bsd
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.\}
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.el .ds tT ucb
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.\"
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.\" Implement .Mx (MirBSD)
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.\"
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.ie "\*(tT"gnu" \{\
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. eo
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. de Mx
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. nr curr-font \n[.f]
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. nr curr-size \n[.ps]
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. ds str-Mx \f[\n[curr-font]]\s[\n[curr-size]u]
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. ds str-Mx1 \*[Tn-font-size]\%MirOS\*[str-Mx]
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. if !\n[arg-limit] \
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. if \n[.$] \{\
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. ds macro-name Mx
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. parse-args \$@
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. \}
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. if (\n[arg-limit] > \n[arg-ptr]) \{\
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. nr arg-ptr +1
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. ie (\n[type\n[arg-ptr]] == 2) \
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. as str-Mx1 \~\*[arg\n[arg-ptr]]
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. el \
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. nr arg-ptr -1
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. \}
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. ds arg\n[arg-ptr] "\*[str-Mx1]
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. nr type\n[arg-ptr] 2
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. ds space\n[arg-ptr] "\*[space]
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. nr num-args (\n[arg-limit] - \n[arg-ptr])
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. nr arg-limit \n[arg-ptr]
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. if \n[num-args] \
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. parse-space-vector
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. print-recursive
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..
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. ec
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. ds sP \s0
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. ds tN \*[Tn-font-size]
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.\}
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.el \{\
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. de Mx
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. nr cF \\n(.f
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. nr cZ \\n(.s
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. ds aa \&\f\\n(cF\s\\n(cZ
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. if \\n(aC==0 \{\
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. ie \\n(.$==0 \&MirOS\\*(aa
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. el .aV \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
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. \}
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. if \\n(aC>\\n(aP \{\
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. nr aP \\n(aP+1
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. ie \\n(C\\n(aP==2 \{\
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. as b1 \&MirOS\ #\&\\*(A\\n(aP\\*(aa
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. ie \\n(aC>\\n(aP \{\
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. nr aP \\n(aP+1
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. nR
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. \}
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. el .aZ
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. \}
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. el \{\
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. as b1 \&MirOS\\*(aa
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. nR
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. \}
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. \}
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..
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.\}
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.\"-
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.Dt LKSH 1
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.Os MirBSD
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.Sh NAME
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.Nm lksh
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.Nd Legacy Korn shell built on mksh
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.Sh SYNOPSIS
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.Nm
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.Bk -words
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.Op Fl +abCefhiklmnprUuvXx
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.Op Fl +o Ar opt
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.Oo
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.Fl c Ar string \*(Ba
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.Fl s \*(Ba
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.Ar file
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.Op Ar args ...
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.Oc
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.Ek
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.Sh DESCRIPTION
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.Nm
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is a command interpreter intended exclusively for running legacy
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shell scripts.
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It is built on
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.Nm mksh ;
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refer to its manual page for details on the scripting language.
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It is recommended to port scripts to
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.Nm mksh
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instead of relying on legacy or idiotic POSIX-mandated behaviour,
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since the MirBSD Korn Shell scripting language is much more consistent.
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.Pp
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Note that it's strongly recommended to invoke
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.Nm
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with at least the
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.Fl o Ic posix
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option, if not both that
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.Em and Fl o Ic sh ,
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to fully enjoy better compatibility to the
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.Tn POSIX
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standard (which is probably why you use
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.Nm
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over
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.Nm mksh
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in the first place) or legacy scripts, respectively.
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.Sh LEGACY MODE
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.Nm
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currently has the following differences from
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.Nm mksh :
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.Bl -bullet
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.It
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.\"XXX TODO: remove (some systems may wish to have lksh as ksh)
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There is no explicit support for interactive use,
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nor any command line editing or history code.
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Hence,
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.Nm
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is not suitable as a user's login shell, either; use
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.Nm mksh
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instead.
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.It
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The
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.Ev KSH_VERSION
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string identifies
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.Nm
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as
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.Dq LEGACY KSH
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instead of
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.Dq MIRBSD KSH .
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Note that the rest of the version string is identical between
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the two shell flavours, and the behaviour and differences can
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change between versions; see the accompanying manual page
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.Xr mksh 1
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for the versions this document applies to.
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.It
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.Nm
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uses
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.Tn POSIX
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arithmetics, which has quite a few implications:
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The data type for arithmetics is the host
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.Tn ISO
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C
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.Vt long
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data type.
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Signed integer wraparound is Undefined Behaviour; this means that...
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.Bd -literal -offset indent
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$ echo $((2147483647 + 1))
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.Ed
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.Pp
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\&... is permitted to, e.g. delete all files on your system
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(the figure differs for non-32-bit systems, the rule doesn't).
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The sign of the result of a modulo operation with at least one
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negative operand is unspecified.
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Shift operations on negative numbers are unspecified.
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Division of the largest negative number by \-1 is Undefined Behaviour.
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The compiler is permitted to delete all data and crash the system
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if Undefined Behaviour occurs (see above for an example).
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.It
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.Nm
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only offers the traditional ten file descriptors to scripts.
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.It
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.\"XXX TODO: move this to FPOSIX
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The rotation arithmetic operators are not available.
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.It
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The shift arithmetic operators take all bits of the second operand into
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account; if they exceed permitted precision, the result is unspecified.
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.It
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.\"XXX TODO: move this to FPOSIX
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The
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.Tn GNU
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.Nm bash
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extension &\*(Gt to redirect stdout and stderr in one go is not parsed.
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.It
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.\"XXX TODO: drop along with allowing interactivity
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The
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.Nm mksh
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command line option
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.Fl T
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is not available.
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.It
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Unless
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.Ic set -o posix
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is active,
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.Nm
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always uses traditional mode for constructs like:
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.Bd -literal -offset indent
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$ set -- $(getopt ab:c "$@")
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$ echo $?
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.Ed
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.Pp
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POSIX mandates this to show 0, but traditional mode
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passes through the errorlevel from the
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.Xr getopt 1
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command.
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.It
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.\"XXX TODO: move to FPOSIX/FSH
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Unlike
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.At
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.Nm ksh ,
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.Nm mksh
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in
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.Fl o Ic posix
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or
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.Fl o Ic sh
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mode and
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.Nm lksh
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do not keep file descriptors \*(Gt 2 private from sub-processes.
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.It
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Functions defined with the
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.Ic function
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reserved word share the shell options
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.Pq Ic set -o
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instead of locally scoping them.
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.El
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.Sh SEE ALSO
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.Xr mksh 1
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.Pp
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.Pa https://www.mirbsd.org/mksh.htm
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.Pp
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.Pa https://www.mirbsd.org/ksh\-chan.htm
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.Sh CAVEATS
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The distinction between the shell variants
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.Pq Nm lksh / Nm mksh
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and shell flags
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.Pq Fl o Ic posix / Ic sh
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will be reworked for an upcoming release.
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.Pp
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To use
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.Nm
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as
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.Pa /bin/sh ,
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compilation to enable
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.Ic set -o posix
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by default if called as
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.Nm sh
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is highly recommended for better standards compliance.
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For better compatibility with legacy scripts, such as many
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.Tn Debian
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maintainer scripts, Upstart and SYSV init scripts, and other
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unfixed scripts, using the compile-time options for enabling
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.Em both
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.Ic set -o posix -o sh
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when the shell is run as
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.Nm sh
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is recommended.
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.Pp
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.Nm
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tries to make a cross between a legacy bourne/posix compatibl-ish
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shell and a legacy pdksh-alike but
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.Dq legacy
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is not exactly specified.
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.Pp
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The
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.Ic set
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built-in command does not currently have all options one would expect
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from a full-blown
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.Nm mksh
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or
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.Nm pdksh .
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.Pp
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Talk to the
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.Mx
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development team using the mailing list at
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.Aq miros\-mksh@mirbsd.org
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or the
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.Li \&#\&!/bin/mksh
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.Pq or Li \&#ksh
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IRC channel at
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.Pa irc.freenode.net
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.Pq Port 6697 SSL, 6667 unencrypted
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if you need any further quirks or assistance,
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and consider migrating your legacy scripts to work with
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.Nm mksh
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instead of requiring
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.Nm .
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