mksh/src/lksh.1 - nest-cam/4320010/mksh - Git at Google

 .\" $MirOS: src/bin/mksh/lksh.1,v 1.18 2016/08/10 18:20:05 tg Exp $
 .\"-
 .\" Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015, 2016
 .\"	mirabilos <m@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 \& *before* a punctuation char that is to not
 .\" be interpreted as punctuation, and especially with two-letter words
 .\" but also (after) a period that does not end a sentence (“e.g.\&”).
 .\" 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: August 10 2016 $
 .\"
 .\" 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.
 .Pp
 Note that it's strongly recommended to invoke
 .Nm
 with at least the
 .Fl o Ic posix
 option, if not both that
 .Em and Fl o Ic sh ,
 to fully enjoy better compatibility to the
 .Tn POSIX
 standard (which is probably why you use
 .Nm
 over
 .Nm mksh
 in the first place) or legacy scripts, respectively.
 .Sh LEGACY MODE
 .Nm
 currently has the following differences from
 .Nm mksh :
 .Bl -bullet
 .It
 .\"XXX TODO: remove (some systems may wish to have lksh as ksh)
 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
 uses
 .Tn POSIX
 arithmetics, which has quite a few implications:
 The data type for arithmetics is the host
 .Tn ISO
 C
 .Vt long
 data type.
 Signed integer wraparound is Undefined Behaviour; this means that...
 .Bd -literal -offset indent
 $ echo $((2147483647 + 1))
 .Ed
 .Pp
 \&... is permitted to, e.g. delete all files on your system
 (the figure differs for non-32-bit systems, the rule doesn't).
 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 (see above for an example).
 .It
 .\"XXX TODO: move this to FPOSIX
 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
 .\"XXX TODO: move this to FPOSIX
 The
 .Tn GNU
 .Nm bash
 extension &\*(Gt to redirect stdout and stderr in one go is not parsed.
 .It
 .\"XXX TODO: drop along with allowing interactivity
 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
 .\"XXX TODO: move to FPOSIX/FSH
 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
 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
 The distinction between the shell variants
 .Pq Nm lksh / Nm mksh
 and shell flags
 .Pq Fl o Ic posix / Ic sh
 will be reworked for an upcoming release.
 .Pp
 To use
 .Nm
 as
 .Pa /bin/sh ,
 compilation to enable
 .Ic set -o posix
 by default if called as
 .Nm sh
 is highly recommended for better standards compliance.
 For better compatibility with legacy scripts, such as many
 .Tn Debian
 maintainer scripts, Upstart and SYSV init scripts, and other
 unfixed scripts, using the compile-time options for enabling
 .Em both
 .Ic set -o posix -o sh
 when the shell is run as
 .Nm sh
 is recommended.
 .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 currently 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 1.18 2016/08/10 18:20:05 tg Exp $
	.\"-
	.\" Copyright (c) 2008, 2009, 2010, 2012, 2013, 2015, 2016
	.\" mirabilos <m@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 \& before a punctuation char that is to not
	.\" be interpreted as punctuation, and especially with two-letter words
	.\" but also (after) a period that does not end a sentence (“e.g.\&”).
	.\" 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: August 10 2016 $
	.\"
	.\" 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.
	.Pp
	Note that it's strongly recommended to invoke
	.Nm
	with at least the
	.Fl o Ic posix
	option, if not both that
	.Em and Fl o Ic sh ,
	to fully enjoy better compatibility to the
	.Tn POSIX
	standard (which is probably why you use
	.Nm
	over
	.Nm mksh
	in the first place) or legacy scripts, respectively.
	.Sh LEGACY MODE
	.Nm
	currently has the following differences from
	.Nm mksh :
	.Bl -bullet
	.It
	.\"XXX TODO: remove (some systems may wish to have lksh as ksh)
	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
	uses
	.Tn POSIX
	arithmetics, which has quite a few implications:
	The data type for arithmetics is the host
	.Tn ISO
	C
	.Vt long
	data type.
	Signed integer wraparound is Undefined Behaviour; this means that...
	.Bd -literal -offset indent
	$ echo $((2147483647 + 1))
	.Ed
	.Pp
	\&... is permitted to, e.g. delete all files on your system
	(the figure differs for non-32-bit systems, the rule doesn't).
	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 (see above for an example).
	.It
	.\"XXX TODO: move this to FPOSIX
	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
	.\"XXX TODO: move this to FPOSIX
	The
	.Tn GNU
	.Nm bash
	extension &\*(Gt to redirect stdout and stderr in one go is not parsed.
	.It
	.\"XXX TODO: drop along with allowing interactivity
	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
	.\"XXX TODO: move to FPOSIX/FSH
	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
	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
	The distinction between the shell variants
	.Pq Nm lksh / Nm mksh
	and shell flags
	.Pq Fl o Ic posix / Ic sh
	will be reworked for an upcoming release.
	.Pp
	To use
	.Nm
	as
	.Pa /bin/sh ,
	compilation to enable
	.Ic set -o posix
	by default if called as
	.Nm sh
	is highly recommended for better standards compliance.
	For better compatibility with legacy scripts, such as many
	.Tn Debian
	maintainer scripts, Upstart and SYSV init scripts, and other
	unfixed scripts, using the compile-time options for enabling
	.Em both
	.Ic set -o posix -o sh
	when the shell is run as
	.Nm sh
	is recommended.
	.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 currently 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 .