src/lksh.1 - platform/external/mksh - Git at Google

 .\" $MirOS: src/bin/mksh/lksh.1,v 1.10 2015/04/12 22:32:12 tg Exp $
 .\"-
 .\" Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015
 .\"	Thorsten “mirabilos” Glaser <tg@mirbsd.org>
 .\"
 .\" Provided that these terms and disclaimer and all copyright notices
 .\" are retained or reproduced in an accompanying document, permission
 .\" is granted to deal in this work without restriction, including un‐
 .\" limited rights to use, publicly perform, distribute, sell, modify,
 .\" merge, give away, or sublicence.
 .\"
 .\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
 .\" the utmost extent permitted by applicable law, neither express nor
 .\" implied; without malicious intent or gross negligence. In no event
 .\" may a licensor, author or contributor be held liable for indirect,
 .\" direct, other damage, loss, or other issues arising in any way out
 .\" of dealing in the work, even if advised of the possibility of such
 .\" damage or existence of a defect, except proven that it results out
 .\" of said person’s immediate fault when using the work as intended.
 .\"-
 .\" Try to make GNU groff and AT&T nroff more compatible
 .\" * ` generates ‘ in gnroff, so use \`
 .\" * ' generates ’ in gnroff, \' generates ´, so use \*(aq
 .\" * - generates ‐ in gnroff, \- generates −, so .tr it to -
 .\"   thus use - for hyphens and \- for minus signs and option dashes
 .\" * ~ is size-reduced and placed atop in groff, so use \*(TI
 .\" * ^ is size-reduced and placed atop in groff, so use \*(ha
 .\" * \(en does not work in nroff, so use \*(en
 .\" * <>| are problematic, so redefine and use \*(Lt\*(Gt\*(Ba
 .\" Also make sure to use \& especially with two-letter words.
 .\" The section after the "doc" macropackage has been loaded contains
 .\" additional code to convene between the UCB mdoc macropackage (and
 .\" its variant as BSD mdoc in groff) and the GNU mdoc macropackage.
 .\"
 .ie \n(.g \{\
 .	if \*[.T]ascii .tr \-\N'45'
 .	if \*[.T]latin1 .tr \-\N'45'
 .	if \*[.T]utf8 .tr \-\N'45'
 .	ds <= \[<=]
 .	ds >= \[>=]
 .	ds Rq \[rq]
 .	ds Lq \[lq]
 .	ds sL \(aq
 .	ds sR \(aq
 .	if \*[.T]utf8 .ds sL `
 .	if \*[.T]ps .ds sL `
 .	if \*[.T]utf8 .ds sR '
 .	if \*[.T]ps .ds sR '
 .	ds aq \(aq
 .	ds TI \(ti
 .	ds ha \(ha
 .	ds en \(en
 .\}
 .el \{\
 .	ds aq '
 .	ds TI ~
 .	ds ha ^
 .	ds en \(em
 .\}
 .\"
 .\" Implement .Dd with the Mdocdate RCS keyword
 .\"
 .rn Dd xD
 .de Dd
 .ie \\$1$Mdocdate: \{\
 .	xD \\$2 \\$3, \\$4
 .\}
 .el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8
 ..
 .\"
 .\" .Dd must come before definition of .Mx, because when called
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
 .Dd $Mdocdate: April 12 2015 $
 .\"
 .\" Check which macro package we use, and do other -mdoc setup.
 .\"
 .ie \n(.g \{\
 .	if \*[.T]utf8 .tr \[la]\*(Lt
 .	if \*[.T]utf8 .tr \[ra]\*(Gt
 .	ie d volume-ds-1 .ds tT gnu
 .	el .ds tT bsd
 .\}
 .el .ds tT ucb
 .\"
 .\" Implement .Mx (MirBSD)
 .\"
 .ie "\*(tT"gnu" \{\
 .	eo
 .	de Mx
 .	nr curr-font \n[.f]
 .	nr curr-size \n[.ps]
 .	ds str-Mx \f[\n[curr-font]]\s[\n[curr-size]u]
 .	ds str-Mx1 \*[Tn-font-size]\%MirOS\*[str-Mx]
 .	if !\n[arg-limit] \
 .	if \n[.$] \{\
 .	ds macro-name Mx
 .	parse-args \$@
 .	\}
 .	if (\n[arg-limit] > \n[arg-ptr]) \{\
 .	nr arg-ptr +1
 .	ie (\n[type\n[arg-ptr]] == 2) \
 .	as str-Mx1 \~\*[arg\n[arg-ptr]]
 .	el \
 .	nr arg-ptr -1
 .	\}
 .	ds arg\n[arg-ptr] "\*[str-Mx1]
 .	nr type\n[arg-ptr] 2
 .	ds space\n[arg-ptr] "\*[space]
 .	nr num-args (\n[arg-limit] - \n[arg-ptr])
 .	nr arg-limit \n[arg-ptr]
 .	if \n[num-args] \
 .	parse-space-vector
 .	print-recursive
 ..
 .	ec
 .	ds sP \s0
 .	ds tN \*[Tn-font-size]
 .\}
 .el \{\
 .	de Mx
 .	nr cF \\n(.f
 .	nr cZ \\n(.s
 .	ds aa \&\f\\n(cF\s\\n(cZ
 .	if \\n(aC==0 \{\
 .		ie \\n(.$==0 \&MirOS\\*(aa
 .		el .aV \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
 .	\}
 .	if \\n(aC>\\n(aP \{\
 .		nr aP \\n(aP+1
 .		ie \\n(C\\n(aP==2 \{\
 .			as b1 \&MirOS\ #\&\\*(A\\n(aP\\*(aa
 .			ie \\n(aC>\\n(aP \{\
 .				nr aP \\n(aP+1
 .				nR
 .			\}
 .			el .aZ
 .		\}
 .		el \{\
 .			as b1 \&MirOS\\*(aa
 .			nR
 .		\}
 .	\}
 ..
 .\}
 .\"-
 .Dt LKSH 1
 .Os MirBSD
 .Sh NAME
 .Nm lksh
 .Nd Legacy Korn shell built on mksh
 .Sh SYNOPSIS
 .Nm
 .Bk -words
 .Op Fl +abCefhiklmnprUuvXx
 .Op Fl +o Ar opt
 .Oo
 .Fl c Ar string \*(Ba
 .Fl s \*(Ba
 .Ar file
 .Op Ar args ...
 .Oc
 .Ek
 .Sh DESCRIPTION
 .Nm
 is a command interpreter intended exclusively for running legacy
 shell scripts.
 It is built on
 .Nm mksh ;
 refer to its manual page for details on the scripting language.
 It is recommended to port scripts to
 .Nm mksh
 instead of relying on legacy or idiotic POSIX-mandated behaviour,
 since the MirBSD Korn Shell scripting language is much more consistent.
 .Sh LEGACY MODE
 .Nm
 currently has the following differences from
 .Nm mksh :
 .Bl -bullet
 .It
 There is no explicit support for interactive use,
 nor any command line editing or history code.
 Hence,
 .Nm
 is not suitable as a user's login shell, either; use
 .Nm mksh
 instead.
 .It
 The
 .Ev KSH_VERSION
 string identifies
 .Nm
 as
 .Dq LEGACY KSH
 instead of
 .Dq MIRBSD KSH .
 Note that the rest of the version string is identical between
 the two shell flavours, and the behaviour and differences can
 change between versions; see the accompanying manual page
 .Xr mksh 1
 for the versions this document applies to.
 .It
 .Nm
 only offers the traditional ten file descriptors to scripts.
 .It
 .Nm
 uses
 .Tn POSIX
 arithmetics, which has quite a few implications:
 The data type for arithmetics is the host ISO C
 .Vt long
 data type.
 Signed integer wraparound is Undefined Behaviour.
 The sign of the result of a modulo operation with at least one
 negative operand is unspecified.
 Shift operations on negative numbers are unspecified.
 Division of the largest negative number by \-1 is Undefined Behaviour.
 The compiler is permitted to delete all data and crash the system
 if Undefined Behaviour occurs.
 .It
 The rotation arithmetic operators are not available.
 .It
 The shift arithmetic operators take all bits of the second operand into
 account; if they exceed permitted precision, the result is unspecified.
 .It
 The
 .Tn GNU
 .Nm bash
 extension &\*(Gt to redirect stdout and stderr in one go is not parsed.
 .It
 The
 .Nm mksh
 command line option
 .Fl T
 is not available.
 .It
 Unless
 .Ic set -o posix
 is active,
 .Nm
 always uses traditional mode for constructs like:
 .Bd -literal -offset indent
 $ set -- $(getopt ab:c "$@")
 $ echo $?
 .Ed
 .Pp
 POSIX mandates this to show 0, but traditional mode
 passes through the errorlevel from the
 .Xr getopt 1
 command.
 .It
 Unlike
 .At
 .Nm ksh ,
 .Nm mksh
 in
 .Fl o Ic posix
 or
 .Fl o Ic sh
 mode and
 .Nm lksh
 do not keep file descriptors \*(Gt 2 private from sub-processes.
 .It
 .Nm lksh
 undefines an alias when a
 .Tn POSIX
 function with the same name is defined,
 to make that function immediately callable.
 In
 .Nm mksh ,
 aliases have precedence; the name must be quoted or
 .Ic unalias Ns ed
 to access it.
 .It
 Functions defined with the
 .Ic function
 reserved word share the shell options
 .Pq Ic set -o
 instead of locally scoping them.
 .El
 .Sh SEE ALSO
 .Xr mksh 1
 .Pp
 .Pa https://www.mirbsd.org/mksh.htm
 .Pp
 .Pa https://www.mirbsd.org/ksh\-chan.htm
 .Sh CAVEATS
 To use
 .Nm
 as
 .Pa /bin/sh ,
 compilation to enable
 .Ic set -o posix
 by default is highly recommended for better standards compliance.
 .Pp
 .Nm
 tries to make a cross between a legacy bourne/posix compatibl-ish
 shell and a legacy pdksh-alike but
 .Dq legacy
 is not exactly specified.
 .Pp
 The
 .Ic set
 built-in command does not have all options one would expect
 from a full-blown
 .Nm mksh
 or
 .Nm pdksh .
 .Pp
 Talk to the
 .Mx
 development team using the mailing list at
 .Aq miros\-mksh@mirbsd.org
 or the
 .Li \&#\&!/bin/mksh
 .Pq or Li \&#ksh
 IRC channel at
 .Pa irc.freenode.net
 .Pq Port 6697 SSL, 6667 unencrypted
 if you need any further quirks or assistance,
 and consider migrating your legacy scripts to work with
 .Nm mksh
 instead of requiring
 .Nm .
	.\" $MirOS: src/bin/mksh/lksh.1,v 1.10 2015/04/12 22:32:12 tg Exp $
	.\"-
	.\" Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015
	.\" Thorsten “mirabilos” Glaser <tg@mirbsd.org>
	.\"
	.\" Provided that these terms and disclaimer and all copyright notices
	.\" are retained or reproduced in an accompanying document, permission
	.\" is granted to deal in this work without restriction, including un‐
	.\" limited rights to use, publicly perform, distribute, sell, modify,
	.\" merge, give away, or sublicence.
	.\"
	.\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
	.\" the utmost extent permitted by applicable law, neither express nor
	.\" implied; without malicious intent or gross negligence. In no event
	.\" may a licensor, author or contributor be held liable for indirect,
	.\" direct, other damage, loss, or other issues arising in any way out
	.\" of dealing in the work, even if advised of the possibility of such
	.\" damage or existence of a defect, except proven that it results out
	.\" of said person’s immediate fault when using the work as intended.
	.\"-
	.\" Try to make GNU groff and AT&T nroff more compatible
	.\" * ` generates ‘ in gnroff, so use \`
	.\" * ' generates ’ in gnroff, \' generates ´, so use \*(aq
	.\" * - generates ‐ in gnroff, \- generates −, so .tr it to -
	.\" thus use - for hyphens and \- for minus signs and option dashes
	.\" * ~ is size-reduced and placed atop in groff, so use \*(TI
	.\" * ^ is size-reduced and placed atop in groff, so use \*(ha
	.\" * \(en does not work in nroff, so use \*(en
	.\" * <>\| are problematic, so redefine and use \(Lt\(Gt\*(Ba
	.\" Also make sure to use \& especially with two-letter words.
	.\" The section after the "doc" macropackage has been loaded contains
	.\" additional code to convene between the UCB mdoc macropackage (and
	.\" its variant as BSD mdoc in groff) and the GNU mdoc macropackage.
	.\"
	.ie \n(.g \{\
	. if \*[.T]ascii .tr \-\N'45'
	. if \*[.T]latin1 .tr \-\N'45'
	. if \*[.T]utf8 .tr \-\N'45'
	. ds <= \[<=]
	. ds >= \[>=]
	. ds Rq \[rq]
	. ds Lq \[lq]
	. ds sL \(aq
	. ds sR \(aq
	. if \*[.T]utf8 .ds sL `
	. if \*[.T]ps .ds sL `
	. if \*[.T]utf8 .ds sR '
	. if \*[.T]ps .ds sR '
	. ds aq \(aq
	. ds TI \(ti
	. ds ha \(ha
	. ds en \(en
	.\}
	.el \{\
	. ds aq '
	. ds TI ~
	. ds ha ^
	. ds en \(em
	.\}
	.\"
	.\" Implement .Dd with the Mdocdate RCS keyword
	.\"
	.rn Dd xD
	.de Dd
	.ie \\$1$Mdocdate: \{\
	. xD \\$2 \\$3, \\$4
	.\}
	.el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8
	..
	.\"
	.\" .Dd must come before definition of .Mx, because when called
	.\" with -mandoc, it might implement .Mx itself, but we want to
	.\" use our own definition. And .Dd must come first, always.
	.\"
	.Dd $Mdocdate: April 12 2015 $
	.\"
	.\" Check which macro package we use, and do other -mdoc setup.
	.\"
	.ie \n(.g \{\
	. if \[.T]utf8 .tr \[la]\(Lt
	. if \[.T]utf8 .tr \[ra]\(Gt
	. ie d volume-ds-1 .ds tT gnu
	. el .ds tT bsd
	.\}
	.el .ds tT ucb
	.\"
	.\" Implement .Mx (MirBSD)
	.\"
	.ie "\*(tT"gnu" \{\
	. eo
	. de Mx
	. nr curr-font \n[.f]
	. nr curr-size \n[.ps]
	. ds str-Mx \f[\n[curr-font]]\s[\n[curr-size]u]
	. ds str-Mx1 \[Tn-font-size]\%MirOS\[str-Mx]
	. if !\n[arg-limit] \
	. if \n[.$] \{\
	. ds macro-name Mx
	. parse-args \$@
	. \}
	. if (\n[arg-limit] > \n[arg-ptr]) \{\
	. nr arg-ptr +1
	. ie (\n[type\n[arg-ptr]] == 2) \
	. as str-Mx1 \~\*[arg\n[arg-ptr]]
	. el \
	. nr arg-ptr -1
	. \}
	. ds arg\n[arg-ptr] "\*[str-Mx1]
	. nr type\n[arg-ptr] 2
	. ds space\n[arg-ptr] "\*[space]
	. nr num-args (\n[arg-limit] - \n[arg-ptr])
	. nr arg-limit \n[arg-ptr]
	. if \n[num-args] \
	. parse-space-vector
	. print-recursive
	..
	. ec
	. ds sP \s0
	. ds tN \*[Tn-font-size]
	.\}
	.el \{\
	. de Mx
	. nr cF \\n(.f
	. nr cZ \\n(.s
	. ds aa \&\f\\n(cF\s\\n(cZ
	. if \\n(aC==0 \{\
	. ie \\n(.$==0 \&MirOS\\*(aa
	. el .aV \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
	. \}
	. if \\n(aC>\\n(aP \{\
	. nr aP \\n(aP+1
	. ie \\n(C\\n(aP==2 \{\
	. as b1 \&MirOS\ #\&\\(A\\n(aP\\(aa
	. ie \\n(aC>\\n(aP \{\
	. nr aP \\n(aP+1
	. nR
	. \}
	. el .aZ
	. \}
	. el \{\
	. as b1 \&MirOS\\*(aa
	. nR
	. \}
	. \}
	..
	.\}
	.\"-
	.Dt LKSH 1
	.Os MirBSD
	.Sh NAME
	.Nm lksh
	.Nd Legacy Korn shell built on mksh
	.Sh SYNOPSIS
	.Nm
	.Bk -words
	.Op Fl +abCefhiklmnprUuvXx
	.Op Fl +o Ar opt
	.Oo
	.Fl c Ar string \*(Ba
	.Fl s \*(Ba
	.Ar file
	.Op Ar args ...
	.Oc
	.Ek
	.Sh DESCRIPTION
	.Nm
	is a command interpreter intended exclusively for running legacy
	shell scripts.
	It is built on
	.Nm mksh ;
	refer to its manual page for details on the scripting language.
	It is recommended to port scripts to
	.Nm mksh
	instead of relying on legacy or idiotic POSIX-mandated behaviour,
	since the MirBSD Korn Shell scripting language is much more consistent.
	.Sh LEGACY MODE
	.Nm
	currently has the following differences from
	.Nm mksh :
	.Bl -bullet
	.It
	There is no explicit support for interactive use,
	nor any command line editing or history code.
	Hence,
	.Nm
	is not suitable as a user's login shell, either; use
	.Nm mksh
	instead.
	.It
	The
	.Ev KSH_VERSION
	string identifies
	.Nm
	as
	.Dq LEGACY KSH
	instead of
	.Dq MIRBSD KSH .
	Note that the rest of the version string is identical between
	the two shell flavours, and the behaviour and differences can
	change between versions; see the accompanying manual page
	.Xr mksh 1
	for the versions this document applies to.
	.It
	.Nm
	only offers the traditional ten file descriptors to scripts.
	.It
	.Nm
	uses
	.Tn POSIX
	arithmetics, which has quite a few implications:
	The data type for arithmetics is the host ISO C
	.Vt long
	data type.
	Signed integer wraparound is Undefined Behaviour.
	The sign of the result of a modulo operation with at least one
	negative operand is unspecified.
	Shift operations on negative numbers are unspecified.
	Division of the largest negative number by \-1 is Undefined Behaviour.
	The compiler is permitted to delete all data and crash the system
	if Undefined Behaviour occurs.
	.It
	The rotation arithmetic operators are not available.
	.It
	The shift arithmetic operators take all bits of the second operand into
	account; if they exceed permitted precision, the result is unspecified.
	.It
	The
	.Tn GNU
	.Nm bash
	extension &\*(Gt to redirect stdout and stderr in one go is not parsed.
	.It
	The
	.Nm mksh
	command line option
	.Fl T
	is not available.
	.It
	Unless
	.Ic set -o posix
	is active,
	.Nm
	always uses traditional mode for constructs like:
	.Bd -literal -offset indent
	$ set -- $(getopt ab:c "$@")
	$ echo $?
	.Ed
	.Pp
	POSIX mandates this to show 0, but traditional mode
	passes through the errorlevel from the
	.Xr getopt 1
	command.
	.It
	Unlike
	.At
	.Nm ksh ,
	.Nm mksh
	in
	.Fl o Ic posix
	or
	.Fl o Ic sh
	mode and
	.Nm lksh
	do not keep file descriptors \*(Gt 2 private from sub-processes.
	.It
	.Nm lksh
	undefines an alias when a
	.Tn POSIX
	function with the same name is defined,
	to make that function immediately callable.
	In
	.Nm mksh ,
	aliases have precedence; the name must be quoted or
	.Ic unalias Ns ed
	to access it.
	.It
	Functions defined with the
	.Ic function
	reserved word share the shell options
	.Pq Ic set -o
	instead of locally scoping them.
	.El
	.Sh SEE ALSO
	.Xr mksh 1
	.Pp
	.Pa https://www.mirbsd.org/mksh.htm
	.Pp
	.Pa https://www.mirbsd.org/ksh\-chan.htm
	.Sh CAVEATS
	To use
	.Nm
	as
	.Pa /bin/sh ,
	compilation to enable
	.Ic set -o posix
	by default is highly recommended for better standards compliance.
	.Pp
	.Nm
	tries to make a cross between a legacy bourne/posix compatibl-ish
	shell and a legacy pdksh-alike but
	.Dq legacy
	is not exactly specified.
	.Pp
	The
	.Ic set
	built-in command does not have all options one would expect
	from a full-blown
	.Nm mksh
	or
	.Nm pdksh .
	.Pp
	Talk to the
	.Mx
	development team using the mailing list at
	.Aq miros\-mksh@mirbsd.org
	or the
	.Li \&#\&!/bin/mksh
	.Pq or Li \&#ksh
	IRC channel at
	.Pa irc.freenode.net
	.Pq Port 6697 SSL, 6667 unencrypted
	if you need any further quirks or assistance,
	and consider migrating your legacy scripts to work with
	.Nm mksh
	instead of requiring
	.Nm .