-.\" $MirOS: src/bin/mksh/mksh.1,v 1.305 2013/02/19 18:45:20 tg Exp $
-.\" $OpenBSD: ksh.1,v 1.145 2013/01/17 21:20:25 jmc Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.320 2013/08/10 14:11:39 tg Exp $
+.\" $OpenBSD: ksh.1,v 1.147 2013/06/13 19:43:09 millert Exp $
.\"-
.\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
.\" 2010, 2011, 2012, 2013
.\" with -mandoc, it might implement .Mx itself, but we want to
.\" use our own definition. And .Dd must come *first*, always.
.\"
-.Dd $Mdocdate: February 19 2013 $
+.Dd $Mdocdate: August 10 2013 $
.\"
.\" Check which macro package we use, and do other -mdoc setup.
.\"
.Nm
.Bk -words
.Op Fl +abCefhiklmnprUuvXx
-.Op Fl T Ar /dev/ttyCn \*(Ba \-
+.Oo
+.Fl T Oo Ar \&! Oc Ns Ar tty
+\*(Ba
+.Ar \&\-
+.Oc
.Op Fl +o Ar option
.Oo
.Fl c Ar string \*(Ba
.It Fl s
The shell reads commands from standard input; all non-option arguments
are positional parameters.
-.It Fl T Ar tty
+.It Fl T Ar name
Spawn
.Nm
on the
.Xr tty 4
device given.
-Superuser only.
+The paths
+.Ar name ,
+.Pa /dev/ttyC Ns Ar name
+and
+.Pa /dev/tty Ns Ar name
+are attempted in order.
+Unless
+.Ar name
+begins with an exclamation mark
+.Pq Sq \&! ,
+this is done in a subshell and returns immediately.
If
-.Ar tty
-is a dash, detach from controlling terminal (daemonise) instead.
+.Ar name
+is a dash
+.Pq Sq \&\- ,
+detach from controlling terminal (daemonise) instead.
.El
.Pp
In addition to the above, the options described in the
last is piped (see
.Xr pipe 2 )
to the standard input of the following command.
-The exit status of a pipeline is that of its last command.
+The exit status of a pipeline is that of its last command, unless the
+.Ic pipefail
+option is set (see there).
All commands of a pipeline are executed in separate subshells;
this is allowed by POSIX but differs from both variants of
.At
.Ic exit
terminates the parent shell.
.Pp
+Another variant of substitution are the valsubs (value substitutions)
+.Pf ${\*(Ba\& Ns Ar command Ns \&;}
+which are also executed in the current environment, like funsubs, but
+share their I/O with the parent; instead, they evaluate to whatever
+the, initially empty, expression-local variable
+.Ev REPLY
+is set to within the
+.Ar command Ns No s .
+.Pp
If a substitution appears outside of double quotes, the results of the
substitution are generally subject to word or field splitting according to
the current value of the
before it is printed.
The default is
.Sq +\ \& .
+You may want to set it to
+.Sq \&[$EPOCHREALTIME]\ \&
+instead, to include timestamps.
.It Ev PWD
The current working directory.
May be unset or
.Nm
but a syntax error in GNU
.Nm bash .
+Setting the
+.Fl o Ar posix
+or
+.Fl o Ar sh
+shell options disable parsing of this redirection;
+it's a compatibility feature to legacy scripts, to
+not be used when writing new shell code.
.It Xo
.No &\*(Gt\*(Ba Ar file ,
.No &\*(Gt\*(Gt Ar file ,
Binary operators:
.Bd -literal -offset indent
,
-= *= /= %= += \-= \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
+= += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt= \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
\*(Ba\*(Ba
&&
\*(Ba
\*(ha
&
== !=
-\*(Lt \*(Lt= \*(Gt= \*(Gt
-\*(Lt\*(Lt \*(Gt\*(Gt
+\*(Lt \*(Lt= \*(Gt \*(Gt=
+\*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt \*(Lt\*(Lt \*(Gt\*(Gt
+ \-
* / %
.Ed
in all forms of arithmetic expressions, except as numeric arguments to the
.Ic test
built-in command.
-It is discouraged to prefix numbers with a sole zero
-.Pq Sq 0 ,
-because some shells may interpret them as base-8 integers.
+Prefixing numbers with a sole digit zero
+.Pq Sq 0
+leads to the shell interpreting it as base-8 integer in
+.Ic posix
+mode
+.Em only ;
+historically, (pd)ksh has never done so either anyway,
+and it's unsafe to do that, but POSIX demands it nowadays.
As a special
.Nm mksh
extension, numbers to the base of one are treated as either (8-bit
.It =
Assignment; the variable on the left is set to the value on the right.
.It Xo
-.No *= /= += \-= \*(Lt\*(Lt=
-.No \*(Gt\*(Gt= &= \*(ha= \*(Ba=
+.No += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt=
+.No \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba=
.Xc
Assignment operators.
.Sm off
.It \*(Lt
Less than; the result is 1 if the left argument is less than the right, 0 if
not.
-.It \*(Lt= \*(Gt= \*(Gt
+.It \*(Lt= \*(Gt \*(Gt=
Less than or equal, greater than or equal, greater than.
See
.Ic \*(Lt .
+.It \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt
+Rotate left (right); the result is similar to shift (see
+.Ic \*(Lt\*(Lt )
+except that the bits shifted out at one end are shifted in
+at the other end, instead of zero or sign bits.
.It \*(Lt\*(Lt \*(Gt\*(Gt
Shift left (right); the result is the left argument with its bits shifted left
(right) by the amount given in the right argument.
.It %
Remainder; the result is the remainder of the division of the left argument by
the right.
-The sign of the result is unspecified if either argument is negative.
.It Xo
.Sm off
.Aq Ar arg1 ?
.Aq Ar arg2 ;
otherwise the result is
.Aq Ar arg3 .
+The non-result argument is not evaluated.
.El
.Ss Co-processes
A co-process (which is a pipeline created with the
shell arguments (i.e. positional parameters $1, $2, etc.)\&
are never visible inside them.
When the shell is determining the location of a command, functions
-are searched after special built-in commands, before regular and
-non-regular built-ins, and before the
+are searched after special built-in commands, before builtins and the
.Ev PATH
is searched.
.Pp
.El
.Ss Command execution
After evaluation of command-line arguments, redirections, and parameter
-assignments, the type of command is determined: a special built-in, a
-function, a regular built-in, or the name of a file to execute found using the
+assignments, the type of command is determined: a special built-in command,
+a function, a normal builtin, or the name of a file to execute found using the
.Ev PATH
parameter.
The checks are made in the above order.
The original
.Nm ksh
and POSIX differ somewhat in which commands are considered
-special or regular:
+special or regular.
.Pp
-POSIX special commands
+POSIX special built-in utilities:
.Pp
.Ic \&. , \&: , break , continue ,
.Ic eval , exec , exit , export ,
.Ic readonly , return , set , shift ,
-.Ic trap , unset , wait
+.Ic times , trap , unset
.Pp
Additional
.Nm
-special commands
-.Pp
-.Ic builtin , global , times , typeset
-.Pp
-Very special commands
-.Pq non-POSIX
+commands keeping assignments:
.Pp
-.Ic alias , readonly , set , typeset
+.Ic builtin , global , typeset , wait
.Pp
-POSIX regular commands
+Builtins that are not special:
.Pp
-.Ic alias , bg , cd , command ,
+.Ic [ , alias , bg , bind ,
+.Ic cat , cd , command , echo ,
.Ic false , fc , fg , getopts ,
-.Ic jobs , kill , read , true ,
-.Ic umask , unalias
-.Pp
-Additional
-.Nm
-regular commands
-.Pp
-.Ic \&[ , chdir , bind , cat ,
-.Ic echo , let , mknod , print ,
-.Ic pwd , realpath , rename , sleep ,
-.Ic test , ulimit , whence
-.Pp
-In the future, the additional
-.Nm
-special and regular commands may be treated
-differently from the POSIX special and regular commands.
+.Ic jobs , kill , let , mknod ,
+.Ic print , pwd , read , realpath ,
+.Ic rename , sleep , test , true ,
+.Ic ulimit , umask , unalias , whence
.Pp
Once the type of command has been determined, any command-line parameter
assignments are performed and exported for the duration of the command.
The null command.
Exit status is set to zero.
.Pp
+.It Ic \&[ Ar expression Ic \&]
+See
+.Ic test .
+.Pp
.It Xo Ic alias
.Oo Fl d \*(Ba t Oo Fl r Oc \*(Ba
.Cm +\-x Oc
.Ev OPTIND ,
may lead to unexpected results.
.Pp
+.It global Ar ...
+See
+.Ic typeset .
+.Pp
.It Xo
.Ic hash
.Op Fl r
is syntactic sugar for
.No let \&" Ns Ar expr Ns \&" .
.Pp
+.It let]
+Internally used alias for
+.Ic let .
+.Pp
.It Xo
.Ic mknod
.Op Fl m Ar mode
.Ic if ,
.Ic until ,
.Ic while ,
-.Ic && ,
-.Ic \*(Ba\*(Ba ,
or
.Ic !\&
statements.
+For
+.Ic &&
+or
+.Ic \*(Ba\*(Ba ,
+only the status of the last command is tested.
.It Fl f \*(Ba Fl o Ic noglob
Do not expand file name patterns.
.It Fl h \*(Ba Fl o Ic trackall
.Ql /
during file name generation.
.It Fl x \*(Ba Fl o Ic xtrace
-Print commands and parameter assignments when they are executed, preceded by
+Print command trees when they are executed, preceded by
the value of
.Ev PS4 .
.It Fl o Ic bgnice
To avoid infinite loops, the shell will exit if
.Dv EOF
is read 13 times in a row.
+.It Fl o Ic inherit\-xtrace
+Do not reset
+.Fl o Ic xtrace
+upon entering functions.
+This is enabled by default.
.It Fl o Ic nohup
Do not kill running jobs with a
.Dv SIGHUP
and
.Ic pwd
commands above for more details.
+.It Fl o Ic pipefail
+Make the exit status of a pipeline (before logically complementing) the
+rightmost non-zero errorlevel, or zero if all commands exited with zero.
.It Fl o Ic posix
Enable a somewhat more
.Px
.Ar n Ns th
occurrence of the last search string;
the direction of the search is the opposite of the last search.
+.It Ar ANSI-CurUp
+Take the characters from the beginning of the line to the current
+cursor position as search string and do a backwards history search
+for lines beginning with this string; keep the cursor position.
+This works only in insert mode and keeps it enabled.
.El
.Pp
Edit commands
.\" Open Source licence.
.\"
See the documentation, CVS, and web site for details.
+.Pp
+The BSD daemon is Copyright \(co Marshall Kirk McKusick.
+The complete legalese is at:
+.Pa https://www.mirbsd.org/TaC\-mksh.txt
+.\"
+.\" This boils down to: feel free to use mksh.ico as application icon
+.\" or shortcut for mksh or mksh/Win32; distro patches are ok (but we
+.\" request they amend $KSH_VERSION when modifying mksh). Authors are
+.\" Marshall Kirk McKusick (UCB), Rick Collette (ekkoBSD), Thorsten
+.\" Glaser, Benny Siegert (MirBSD), Michael Langguth (mksh/Win32).
+.\"
+.\" As far as MirBSD is concerned, the files themselves are free
+.\" to modification and distribution under BSD/MirOS Licence, the
+.\" restriction on use stems only from trademark law's requirement
+.\" to protect it or lose it, which McKusick almost did.
+.\"
.Sh CAVEATS
.Nm
only supports the Unicode BMP (Basic Multilingual Plane).
-It has a different scope model from
+.Pp
+.Nm
+has a different scope model from
.At
.Nm ksh ,
which leads to subtile differences in semantics for identical builtins.
+This can cause issues with a
+.Ic nameref
+to suddenly point to a local variable by accident; fixing this is hard.
.Pp
The parts of a pipeline, like below, are executed in subshells.
-Thus, variable assignments inside them fail.
+Thus, variable assignments inside them are not visible in the
+surrounding execution environment.
Use co-processes instead.
.Bd -literal -offset indent
foo \*(Ba bar \*(Ba read baz # will not change $baz
foo \*(Ba bar \*(Ba& read \-p baz # will, however, do so
.Ed
+.Pp
+.Nm mksh
+provides a consistent set of 32-bit integer arithmetics, both signed
+and unsigned, with defined wraparound and sign of the result of a modulo
+operation, even (defying POSIX) on 64-bit systems.
+If you require 64-bit integer arithmetics, use
+.Nm lksh Pq legacy mksh
+instead, but be aware that, in POSIX, it's legal for the OS to make
+.Li print $((2147483647 + 1))
+delete all files on your system, as it's Undefined Behaviour.
.Sh BUGS
Suspending (using \*(haZ) pipelines like the one below will only suspend
the currently running part of the pipeline; in this example,
.Ed
.Pp
This document attempts to describe
-.Nm mksh\ R43
+.Nm mksh\ R48
and up,
compiled without any options impacting functionality, such as
.Dv MKSH_SMALL ,
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