lksh(1) BSD General Commands Manual lksh(1)
NAME
lksh -- Legacy Korn shell built on mksh
SYNOPSIS
lksh [-+abCefhiklmnprUuvXx] [-+o opt] [-c string | -s | file [args ...]]
DESCRIPTION
lksh is a command interpreter intended exclusively for running legacy
shell scripts. It is built on mksh; refer to its manual page for details
on the scripting language. It is recommended to port scripts to mksh
instead of relying on legacy or idiotic POSIX-mandated behaviour, since
the MirBSD Korn Shell scripting language is much more consistent.
LEGACY MODE
lksh has the following differences from mksh:
o There is no explicit support for interactive use, nor any command
line editing or history code. Hence, lksh is not suitable as a
user's login shell, either; use mksh instead.
o The KSH_VERSION string identifies lksh as ``LEGACY KSH'' instead of
``MIRBSD KSH''.
o lksh only offers the traditional ten file descriptors to scripts.
o lksh uses POSIX arithmetics, which has quite a few implications: The
data type for arithmetics is the host ISO C 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 com-
piler is permitted to delete all data and crash the system if Unde-
fined Behaviour occurs.
o The rotation arithmetic operators are not available.
o The shift arithmetic operators take all bits of the second operand
into account; if they exceed permitted precision, the result is
unspecified.
o The GNU bash extension &> to redirect stdout and stderr in one go is
not parsed.
o The mksh command line option -T is not available.
o Unless set -o posix is active, lksh always uses traditional mode for
constructs like:
$ set -- $(getopt ab:c "$@")
$ echo $?
POSIX mandates this to show 0, but traditional mode passes through
the errorlevel from the getopt(1) command.
o lksh, unlike AT&T UNIX ksh, does not keep file descriptors > 2 pri-
vate.
SEE ALSO
mksh(1)
https://www.mirbsd.org/mksh.htm
https://www.mirbsd.org/ksh-chan.htm
CAVEATS
To use lksh as /bin/sh, compilation to enable set -o posix by default is
highly recommended for better standards compliance.
lksh tries to make a cross between a legacy bourne/posix compatibl-ish
shell and a legacy pdksh-alike but ``legacy'' is not exactly specified.
The set built-in command does not have all options one would expect from
a full-blown mksh or pdksh.
Talk to the MirOS development team using the mailing list at
<miros-mksh@mirbsd.org> or the #!/bin/mksh (or #ksh) IRC channel at
irc.freenode.net (Port 6697 SSL, 6667 unencrypted) if you need any fur-
ther quirks or assistance, and consider migrating your legacy scripts to
work with mksh instead of requiring lksh.
MirBSD May 22, 2013 MirBSD
mksh R47 - Generated Sun Aug 25 10:37:46 CDT 2013