commit: 701fce456110a9d42429c0d08a1d755b8aa6858c
parent: 507638d422b5537e7652f70592c24c51cbdfc056
author: Brian Callahan <dodonpachi-github@mailinator.com>
date: Tue, 7 Apr 2015 17:47:34 -0400
Update man pages.
2 files changed, 2085 insertions(+), 3852 deletions(-)
diff --git a/oksh.1 b/oksh.1
@@ -1,8 +1,8 @@
-.\" $OpenBSD: ksh.1,v 1.155 2014/12/09 15:37:13 schwarze Exp $
+.\" $OpenBSD: ksh.1,v 1.159 2015/03/25 12:10:52 jca Exp $
.\"
.\" Public Domain
.\"
-.Dd $Mdocdate: December 9 2014 $
+.Dd $Mdocdate: March 25 2015 $
.Dt OKSH 1
.Os
.Sh NAME
@@ -495,9 +495,9 @@ and
are reserved words, not meta-characters.
.It Xo case Ar word No in
.Oo Op \&(
-.Ar \ pattern
-.Op \*(Ba Ar pattern
-.No ... No )
+.Ar pattern
+.Op | Ar pattern
+.No ... )
.Ar list No ;;\ \& Oc ... esac
.Xc
The
@@ -1347,6 +1347,8 @@ It works the same way as
.Ev PATH
for those directories not beginning with
.Ql /
+or
+.Ql .\&
in
.Ic cd
commands.
@@ -1491,7 +1493,7 @@ The list is colon separated, and each file may be followed by a
.Ql \&?
and a message to be printed if new mail has arrived.
Command, parameter, and
-arithmetic substitution is performed on the message, and, during substitution,
+arithmetic substitution is performed on the message and, during substitution,
the parameter
.Ic $_
contains the name of the file.
@@ -2827,7 +2829,7 @@ The
.Fl x
option sets
.Pq Ic +x No clears
-the export attribute of an alias, or, if no names are given, lists the aliases
+the export attribute of an alias or, if no names are given, lists the aliases
with the export attribute (exporting an alias has no effect).
.Pp
.It Ic bg Op Ar job ...
@@ -4165,7 +4167,7 @@ A command that exits with a zero value.
.Op Fl R Ns Op Ar n
.Op Fl Z Ns Op Ar n
.Op Fl i Ns Op Ar n
-.No \*(Ba Fl f Op Fl tux
+.No \&| Fl f Op Fl tux
.Oc
.Oo
.Ar name
@@ -4557,7 +4559,7 @@ sign
Other percent sequences can also be used to refer to jobs:
.Bl -tag -width "%+ | %% | %XX"
.It %+ \*(Ba %% \*(Ba %
-The most recently stopped job, or, if there are no stopped jobs, the oldest
+The most recently stopped job or, if there are no stopped jobs, the oldest
running job.
.It %-
The job that would be the
@@ -4808,7 +4810,10 @@ command above.
Deletes
.Ar n
characters before the cursor.
-.It delete-char-forward: Op Ar n
+.It Xo delete-char-forward:
+.Op Ar n
+.No Delete
+.Xc
Deletes
.Ar n
characters after the cursor.
diff --git a/sh.1 b/sh.1
@@ -1,3976 +1,2204 @@
-.\" $OpenBSD: sh.1,v 1.99 2014/12/09 15:37:13 schwarze Exp $
+.\" $OpenBSD: sh.1,v 1.126 2015/03/31 21:23:34 jmc Exp $
.\"
-.\" Public Domain
+.\" Copyright (c) 2015 Jason McIntyre <jmc@openbsd.org>
.\"
-.Dd $Mdocdate: December 9 2014 $
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.\"
+.Dd $Mdocdate: March 31 2015 $
.Dt SH 1
.Os
.Sh NAME
.Nm sh
-.Nd public domain Bourne shell
+.Nd command language interpreter
.Sh SYNOPSIS
.Nm sh
-.Bk -words
-.Op Fl +abCefhiklmnpruvXx
-.Op Fl +o Ar option
-.Op Fl c Ar string \*(Ba Fl s \*(Ba Ar file Op Ar argument ...
-.Ek
+.Op Fl abCefhimnuvx
+.Op Fl o Ar option
+.Op Fl c Ar string | Fl s | Ar file
.Sh DESCRIPTION
+The
.Nm
-is a reimplementation of the Bourne shell, a command interpreter for both
-interactive and script use.
-.Pp
-The options are as follows:
-.Bl -tag -width Ds
-.It Fl c Ar string
+utility is a
+.Em command language interpreter :
+it reads its input,
+breaks it down into parts,
+and then executes those parts.
+Its chief uses are in interfacing between the user and the operating system,
+reading commands on the command line,
+and in chaining together groups of commands in a very flexible manner,
+through a shell script.
+.Pp
+This version of
.Nm
-will execute the command(s) contained in
+is actually
+.Nm ksh
+in disguise.
+As such, it will also accept options documented in
+.Xr ksh 1 .
+This manual page describes only features
+relevant to a POSIX compliant
+.Nm .
+If portability is a concern,
+use only those features described in this page.
+.Pp
+The shell receives input as follows:
+.Pp
+.Bl -tag -width "-c stringXXX" -offset indent -compact
+.It Fl c Ar string
+Read commands from
.Ar string .
-.It Fl i
-Interactive shell.
-A shell is
-.Dq interactive
-if this
-option is used or if both standard input and standard error are attached
-to a
-.Xr tty 4 .
-An interactive shell has job control enabled, ignores the
-.Dv SIGINT ,
-.Dv SIGQUIT ,
-and
-.Dv SIGTERM
-signals, and prints prompts before reading input (see the
-.Ev PS1
-and
-.Ev PS2
-parameters).
-For non-interactive shells, the
-.Ic trackall
-option is on by default (see the
-.Ic set
-command below).
-.It Fl l
-Login shell.
-If the basename the shell is called with (i.e. argv[0])
-starts with
-.Ql -
-or if this option is used,
-the shell is assumed to be a login shell and the shell reads and executes
-the contents of
-.Pa /etc/profile
-and
-.Pa $HOME/.profile
-if they exist and are readable.
-.It Fl p
-Privileged shell.
-A shell is
-.Dq privileged
-if this option is used
-or if the real user ID or group ID does not match the
-effective user ID or group ID (see
-.Xr getuid 2
-and
-.Xr getgid 2 ) .
-A privileged shell does not process
-.Pa $HOME/.profile
-nor the
-.Ev ENV
-parameter (see below).
-Instead, the file
-.Pa /etc/suid_profile
-is processed.
-Clearing the privileged option causes the shell to set
-its effective user ID (group ID) to its real user ID (group ID).
-.It Fl r
-Restricted shell.
-A shell is
-.Dq restricted
-if this
-option is used;
-if the basename the shell was invoked with was
-.Dq rsh ;
-or if the
-.Ev SHELL
-parameter is set to
-.Dq rsh .
-The following restrictions come into effect after the shell processes any
-profile and
-.Ev ENV
-files:
-.Pp
-.Bl -bullet -compact
-.It
-The
-.Ic cd
-command is disabled.
-.It
-The
-.Ev SHELL ,
-.Ev ENV ,
-and
-.Ev PATH
-parameters cannot be changed.
-.It
-Command names can't be specified with absolute or relative paths.
-.It
-The
-.Fl p
-option of the built-in command
-.Ic command
-can't be used.
-.It
-Redirections that create files can't be used (i.e.\&
-.Ql \*(Gt ,
-.Ql \*(Gt\*(Ba ,
-.Ql \*(Gt\*(Gt ,
-.Ql \*(Lt\*(Gt ) .
-.El
.It Fl s
-The shell reads commands from standard input; all non-option arguments
-are positional parameters.
+Read commands from standard input
+(the default).
+.It Ar file
+Read commands from
+.Ar file .
.El
.Pp
-In addition to the above, the options described in the
+The options below can be specified with a
+.Sq Cm +
+rather than
+.Sq Fl ,
+meaning to unset the option.
+They can also be set or unset using the
.Ic set
-built-in command can also be used on the command line:
-both
-.Op Fl +abCefhkmnuvXx
-and
-.Op Fl +o Ar option
-can be used for single letter or long options, respectively.
-.Pp
-If neither the
-.Fl c
-nor the
-.Fl s
-option is specified, the first non-option argument specifies the name
-of a file the shell reads commands from.
-If there are no non-option
-arguments, the shell reads commands from the standard input.
-The name of the shell (i.e. the contents of $0)
-is determined as follows: if the
-.Fl c
-option is used and there is a non-option argument, it is used as the name;
-if commands are being read from a file, the file is used as the name;
-otherwise, the basename the shell was called with (i.e. argv[0]) is used.
-.Pp
-If the
-.Ev ENV
-parameter is set when an interactive shell starts (or,
-in the case of login shells,
-after any profiles are processed), its value is subjected to parameter,
-command, arithmetic, and tilde
-.Pq Sq ~
-substitution and the resulting file
-(if any) is read and executed.
-.Pp
-The exit status of the shell is 127 if the command file specified on the
-command line could not be opened, or non-zero if a fatal syntax error
-occurred during the execution of a script.
-In the absence of fatal errors,
-the exit status is that of the last command executed, or zero, if no
-command is executed.
-.Ss Command syntax
-The shell begins parsing its input by breaking it into
-.Em words .
-Words, which are sequences of characters, are delimited by unquoted whitespace
-characters (space, tab, and newline) or meta-characters
-.Po
-.Ql \*(Lt ,
-.Ql \*(Gt ,
-.Ql \*(Ba ,
-.Ql \&; ,
-.Ql \&( ,
-.Ql \&) ,
-and
-.Ql &
-.Pc .
-Aside from delimiting words, spaces and tabs are ignored, while newlines
-usually delimit commands.
-The meta-characters are used in building the following
-.Em tokens :
-.Ql \*(Lt ,
-.Ql \*(Lt& ,
-.Ql \*(Lt\*(Lt ,
-.Ql \*(Gt ,
-.Ql \*(Gt& ,
-.Ql \*(Gt\*(Gt ,
-etc. are used to specify redirections (see
-.Sx Input/output redirection
-below);
-.Ql \*(Ba
-is used to create pipelines;
-.Ql \&;
-is used to separate commands;
-.Ql &
-is used to create asynchronous pipelines;
-.Ql &&
-and
-.Ql ||
-are used to specify conditional execution;
-.Ql ;;
-is used in
-.Ic case
-statements;
-and lastly,
-.Ql \&( .. )\&
-is used to create subshells.
-.Pp
-Whitespace and meta-characters can be quoted individually using a backslash
-.Pq Sq \e ,
-or in groups using double
-.Pq Sq \&"
-or single
-.Pq Sq '
-quotes.
-Note that the following characters are also treated specially by the
-shell and must be quoted if they are to represent themselves:
-.Ql \e ,
-.Ql \&" ,
-.Ql ' ,
-.Ql # ,
-.Ql $ ,
-.Ql ` ,
-.Ql ~ ,
-.Ql { ,
-.Ql } ,
-.Ql * ,
-.Ql \&? ,
-and
-.Ql \&[ .
-The first three of these are the above mentioned quoting characters (see
-.Sx Quoting
-below);
-.Ql # ,
-if used at the beginning of a word, introduces a comment \(em everything after
-the
-.Ql #
-up to the nearest newline is ignored;
-.Ql $
-is used to introduce parameter, command, and arithmetic substitutions (see
-.Sx Substitution
-below);
-.Ql `
-introduces an old-style command substitution (see
-.Sx Substitution
-below);
-.Ql ~
-begins a directory expansion (see
-.Sx Tilde expansion
-below);
-and finally,
-.Ql * ,
-.Ql \&? ,
-and
-.Ql \&[
-are used in file name generation (see
-.Sx File name patterns
-below).
-.Pp
-As words and tokens are parsed, the shell builds commands, of which there
-are two basic types:
-.Em simple-commands ,
-typically programs that are executed, and
-.Em compound-commands ,
-such as
-.Ic for
-and
-.Ic if
-statements, grouping constructs, and function definitions.
-.Pp
-A simple-command consists of some combination of parameter assignments
-(see
-.Sx Parameters
-below),
-input/output redirections (see
-.Sx Input/output redirections
-below),
-and command words; the only restriction is that parameter assignments come
-before any command words.
-The command words, if any, define the command
-that is to be executed and its arguments.
-The command may be a shell built-in command, a function,
-or an external command
-(i.e. a separate executable file that is located using the
-.Ev PATH
-parameter; see
-.Sx Command execution
-below).
-Note that all command constructs have an exit status: for external commands,
-this is related to the status returned by
-.Xr wait 2
-(if the command could not be found, the exit status is 127; if it could not
-be executed, the exit status is 126); the exit status of other command
-constructs (built-in commands, functions, compound-commands, pipelines, lists,
-etc.) are all well-defined and are described where the construct is
-described.
-The exit status of a command consisting only of parameter
-assignments is that of the last command substitution performed during the
-parameter assignment or 0 if there were no command substitutions.
-.Pp
-Commands can be chained together using the
-.Ql |
-token to form pipelines, in which the standard output of each command but 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.
-A pipeline may be prefixed by the
-.Ql \&!
-reserved word, which causes the exit status of the pipeline to be logically
-complemented: if the original status was 0, the complemented status will be 1;
-if the original status was not 0, the complemented status will be 0.
-.Pp
-.Em Lists
-of commands can be created by separating pipelines by any of the following
-tokens:
-.Ql && ,
-.Ql || ,
-.Ql & ,
-.Ql |& ,
-and
-.Ql \&; .
-The first two are for conditional execution:
-.Dq Ar cmd1 No && Ar cmd2
-executes
-.Ar cmd2
-only if the exit status of
-.Ar cmd1
-is zero;
-.Ql ||
-is the opposite \(em
-.Ar cmd2
-is executed only if the exit status of
-.Ar cmd1
-is non-zero.
-.Ql &&
-and
-.Ql ||
-have equal precedence which is higher than that of
-.Ql & ,
-.Ql |& ,
-and
-.Ql \&; ,
-which also have equal precedence.
-Note that the
-.Ql &&
-and
-.Ql ||
-operators are
-.Qq left-associative .
-For example, both of these commands will print only
-.Qq bar :
-.Bd -literal -offset indent
-$ false && echo foo || echo bar
-$ true || echo foo && echo bar
-.Ed
-.Pp
-The
-.Ql &
-token causes the preceding command to be executed asynchronously; that is,
-the shell starts the command but does not wait for it to complete (the shell
-does keep track of the status of asynchronous commands; see
-.Sx Job control
-below).
-When an asynchronous command is started when job control is disabled
-(i.e. in most scripts), the command is started with signals
-.Dv SIGINT
-and
-.Dv SIGQUIT
-ignored and with input redirected from
-.Pa /dev/null
-(however, redirections specified in the asynchronous command have precedence).
-Note that a command must follow the
-.Ql &&
-and
-.Ql ||
-operators, while it need not follow
-.Ql & ,
-.Ql |& ,
-or
-.Ql \&; .
-The exit status of a list is that of the last command executed, with the
-exception of asynchronous lists, for which the exit status is 0.
-.Pp
-Compound commands are created using the following reserved words.
-These words
-are only recognized if they are unquoted and if they are used as the first
-word of a command (i.e. they can't be preceded by parameter assignments or
-redirections):
-.Bd -literal -offset indent
-case esac in while ]]
-do fi name ! {
-done for select ( }
-elif function then )
-else if until [[
-.Ed
-.Pp
-.Sy Note :
-Some shells (but not this one) execute control structure commands in a
-subshell when one or more of their file descriptors are redirected, so any
-environment changes inside them may fail.
-To be portable, the
-.Ic exec
-statement should be used instead to redirect file descriptors before the
-control structure.
-.Pp
-In the following compound command descriptions, command lists (denoted as
-.Em list )
-that are followed by reserved words must end with a semicolon, a newline, or
-a (syntactically correct) reserved word.
-For example, the following are all valid:
-.Bd -literal -offset indent
-$ { echo foo; echo bar; }
-$ { echo foo; echo bar\*(Ltnewline\*(Gt }
-$ { { echo foo; echo bar; } }
-.Ed
-.Pp
-This is not valid:
-.Pp
-.Dl $ { echo foo; echo bar }
-.Bl -tag -width Ds
-.It Pq Ar list
-Execute
-.Ar list
-in a subshell.
-There is no implicit way to pass environment changes from a
-subshell back to its parent.
-.It { Ar list ; No }
-Compound construct;
-.Ar list
-is executed, but not in a subshell.
-Note that
-.Ql {
-and
-.Ql }
-are reserved words, not meta-characters.
-.It Xo case Ar word No in
-.Oo Op \&(
-.Ar \ pattern
-.Op \*(Ba Ar pattern
-.No ... No )
-.Ar list No ;;\ \& Oc ... esac
-.Xc
-The
-.Ic case
-statement attempts to match
-.Ar word
-against a specified
-.Ar pattern ;
-the
-.Ar list
-associated with the first successfully matched pattern is executed.
-Patterns used in
-.Ic case
-statements are the same as those used for file name patterns except that the
-restrictions regarding
-.Ql \&.
-and
-.Ql /
-are dropped.
-Note that any unquoted space before and after a pattern is
-stripped; any space within a pattern must be quoted.
-Both the word and the
-patterns are subject to parameter, command, and arithmetic substitution, as
-well as tilde substitution.
-For historical reasons, open and close braces may be used instead of
-.Ic in
-and
-.Ic esac
-e.g.\&
-.Ic case $foo { *) echo bar; } .
-The exit status of a
-.Ic case
-statement is that of the executed
-.Ar list ;
-if no
-.Ar list
-is executed, the exit status is zero.
-.It Xo for Ar name
-.Oo in Ar word No ... Oc ;
-.No do Ar list ; No done
-.Xc
-For each
-.Ar word
-in the specified word list, the parameter
-.Ar name
-is set to the word and
-.Ar list
-is executed.
-If
-.Ic in
-is not used to specify a word list, the positional parameters
-($1, $2, etc.)\&
-are used instead.
-For historical reasons, open and close braces may be used instead of
-.Ic do
-and
-.Ic done
-e.g.\&
-.Ic for i; { echo $i; } .
-The exit status of a
-.Ic for
-statement is the last exit status of
-.Ar list ;
-if
-.Ar list
-is never executed, the exit status is zero.
-.It Xo if Ar list ;
-.No then Ar list ;
-.Oo elif Ar list ;
-.No then Ar list ; Oc
-.No ...
-.Oo else Ar list ; Oc
-.No fi
-.Xc
-If the exit status of the first
-.Ar list
-is zero, the second
-.Ar list
-is executed; otherwise, the
-.Ar list
-following the
-.Ic elif ,
-if any, is executed with similar consequences.
-If all the lists following the
-.Ic if
-and
-.Ic elif Ns s
-fail (i.e. exit with non-zero status), the
-.Ar list
-following the
-.Ic else
-is executed.
-The exit status of an
-.Ic if
-statement is that of non-conditional
-.Ar list
-that is executed; if no non-conditional
-.Ar list
-is executed, the exit status is zero.
-.It Xo select Ar name
-.Oo in Ar word No ... Oc ;
-.No do Ar list ; No done
-.Xc
-The
-.Ic select
-statement provides an automatic method of presenting the user with a menu and
-selecting from it.
-An enumerated list of the specified
-.Ar word Ns (s)
-is printed on standard error, followed by a prompt
-.Po
-.Ev PS3: normally
-.Sq #?\ \&
-.Pc .
-A number corresponding to one of the enumerated words is then read from
-standard input,
-.Ar name
-is set to the selected word (or unset if the selection is not valid),
-.Ev REPLY
-is set to what was read (leading/trailing space is stripped), and
-.Ar list
-is executed.
-If a blank line (i.e. zero or more
-.Ev IFS
-characters) is entered, the menu is reprinted without executing
-.Ar list .
-.Pp
-When
-.Ar list
-completes, the enumerated list is printed if
-.Ev REPLY
-is
-.Dv NULL ,
-the prompt is printed, and so on.
-This process continues until an end-of-file
-is read, an interrupt is received, or a
-.Ic break
-statement is executed inside the loop.
-If
-.Dq in word ...
-is omitted, the positional parameters are used
-(i.e. $1, $2, etc.).
-For historical reasons, open and close braces may be used instead of
-.Ic do
-and
-.Ic done
-e.g.\&
-.Ic select i; { echo $i; } .
-The exit status of a
-.Ic select
-statement is zero if a
-.Ic break
-statement is used to exit the loop, non-zero otherwise.
-.It Xo until Ar list ;
-.No do Ar list ;
-.No done
-.Xc
-This works like
-.Ic while ,
-except that the body is executed only while the exit status of the first
-.Ar list
-is non-zero.
-.It Xo while Ar list ;
-.No do Ar list ;
-.No done
-.Xc
-A
-.Ic while
-is a pre-checked loop.
-Its body is executed as often as the exit status of the first
-.Ar list
-is zero.
-The exit status of a
-.Ic while
-statement is the last exit status of the
-.Ar list
-in the body of the loop; if the body is not executed, the exit status is zero.
-.It Xo function Ar name
-.No { Ar list ; No }
-.Xc
-Defines the function
-.Ar name
-(see
-.Sx Functions
-below).
-Note that redirections specified after a function definition are
-performed whenever the function is executed, not when the function definition
-is executed.
-.It Ar name Ns () Ar command
-Mostly the same as
-.Ic function
-(see
-.Sx Functions
-below).
-.It Bq Bq Ar \ \&expression\ \&
-Similar to the
-.Ic test
-and
-.Ic \&[ ... \&]
-commands (described later), with the following exceptions:
-.Bl -bullet -offset indent
-.It
-Field splitting and file name generation are not performed on arguments.
-.It
-The
-.Fl a
-.Pq AND
-and
-.Fl o
-.Pq OR
-operators are replaced with
-.Ql &&
-and
-.Ql || ,
-respectively.
-.It
-Operators (e.g.\&
-.Sq Fl f ,
-.Sq = ,
-.Sq \&! )
-must be unquoted.
-.It
-The second operand of the
-.Sq !=
-and
-.Sq =
-expressions are patterns (e.g. the comparison
-.Ic [[ foobar = f*r ]]
-succeeds).
-.It
-There are two additional binary operators,
-.Ql \*(Lt
-and
-.Ql \*(Gt ,
-which return true if their first string operand is less than, or greater than,
-their second string operand, respectively.
-.It
-The single argument form of
-.Ic test ,
-which tests if the argument has a non-zero length, is not valid; explicit
-operators must always be used e.g. instead of
-.No \&[ Ar str No \&]
-use
-.No \&[[ -n Ar str No \&]] .
-.It
-Parameter, command, and arithmetic substitutions are performed as expressions
-are evaluated and lazy expression evaluation is used for the
-.Ql &&
-and
-.Ql ||
-operators.
-This means that in the following statement,
-.Ic $(\*(Lt foo)
-is evaluated if and only if the file
-.Pa foo
-exists and is readable:
-.Bd -literal -offset indent
-$ [[ -r foo && $(\*(Lt foo) = b*r ]]
-.Ed
-.El
-.El
-.Ss Quoting
-Quoting is used to prevent the shell from treating characters or words
-specially.
-There are three methods of quoting.
-First,
-.Ql \e
-quotes the following character, unless it is at the end of a line, in which
-case both the
-.Ql \e
-and the newline are stripped.
-Second, a single quote
-.Pq Sq '
-quotes everything up to the next single quote (this may span lines).
-Third, a double quote
-.Pq Sq \&"
-quotes all characters, except
-.Ql $ ,
-.Ql `
-and
-.Ql \e ,
-up to the next unquoted double quote.
-.Ql $
-and
-.Ql `
-inside double quotes have their usual meaning (i.e. parameter, command, or
-arithmetic substitution) except no field splitting is carried out on the
-results of double-quoted substitutions.
-If a
-.Ql \e
-inside a double-quoted string is followed by
-.Ql \e ,
-.Ql $ ,
-.Ql ` ,
-or
-.Ql \&" ,
-it is replaced by the second character; if it is followed by a newline, both
-the
-.Ql \e
-and the newline are stripped; otherwise, both the
-.Ql \e
-and the character following are unchanged.
-.Pp
-.Sy Note :
-See
-.Sx POSIX mode
-below for a special rule regarding
-differences in quoting when the shell is in POSIX mode.
-.Ss Aliases
-There are two types of aliases: normal command aliases and tracked aliases.
-Command aliases are normally used as a short hand for a long or often used
command.
-The shell expands command aliases (i.e. substitutes the alias name
-for its value) when it reads the first word of a command.
-An expanded alias is re-processed to check for more aliases.
-If a command alias ends in a
-space or tab, the following word is also checked for alias expansion.
-The alias expansion process stops when a word that is not an alias is found,
-when a quoted word is found, or when an alias word that is currently being
-expanded is found.
-.Pp
-The following command aliases are defined automatically by the shell:
-.Bd -literal -offset indent
-hash='alias -t'
-type='whence -v'
-.Ed
-.Pp
-Tracked aliases allow the shell to remember where it found a particular
-command.
-The first time the shell does a path search for a command that is
-marked as a tracked alias, it saves the full path of the command.
-The next
-time the command is executed, the shell checks the saved path to see that it
-is still valid, and if so, avoids repeating the path search.
-Tracked aliases can be listed and created using
-.Ic alias -t .
-Note that changing the
-.Ev PATH
-parameter clears the saved paths for all tracked aliases.
-If the
-.Ic trackall
-option is set (i.e.\&
-.Ic set -o Ic trackall
-or
-.Ic set -h ) ,
-the shell tracks all commands.
-This option is set automatically for non-interactive shells.
-For interactive shells, only the following commands are
-automatically tracked:
-.Xr cat 1 ,
-.Xr cc 1 ,
-.Xr chmod 1 ,
-.Xr cp 1 ,
-.Xr date 1 ,
-.Xr ed 1 ,
-.Xr emacs 1 ,
-.Xr grep 1 ,
-.Xr ls 1 ,
-.Xr mail 1 ,
-.Xr make 1 ,
-.Xr mv 1 ,
-.Xr pr 1 ,
-.Xr rm 1 ,
-.Xr sed 1 ,
-.Xr vi 1 ,
-and
-.Xr who 1 .
-.Ss Substitution
-The first step the shell takes in executing a simple-command is to perform
-substitutions on the words of the command.
-There are three kinds of
-substitution: parameter, command, and arithmetic.
-Parameter substitutions,
-which are described in detail in the next section, take the form
-.Pf $ Ns Ar name
-or
-.Pf ${ Ns Ar ... Ns } ;
-command substitutions take the form
-.Pf $( Ns Ar command Ns \&)
-or
-.Pf ` Ns Ar command Ns ` ;
-and arithmetic substitutions take the form
-.Pf $(( Ns Ar expression Ns )) .
-.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
-.Ev IFS
-parameter.
-The
-.Ev IFS
-parameter specifies a list of characters which are used to break a string up
-into several words; any characters from the set space, tab, and newline that
-appear in the
-.Ev IFS
-characters are called
-.Dq IFS whitespace .
-Sequences of one or more
-.Ev IFS
-whitespace characters, in combination with zero or one
-.Pf non- Ev IFS
-whitespace
-characters, delimit a field.
-As a special case, leading and trailing
-.Ev IFS
-whitespace is stripped (i.e. no leading or trailing empty field is created by
-it); leading
-.Pf non- Ev IFS
-whitespace does create an empty field.
-.Pp
-Example: If
-.Ev IFS
-is set to
-.Dq \*(Ltspace\*(Gt: ,
-and VAR is set to
-.Dq \*(Ltspace\*(GtA\*(Ltspace\*(Gt:\*(Ltspace\*(Gt\*(Ltspace\*(GtB::D ,
-the substitution for $VAR results in four fields:
-.Sq A ,
-.Sq B ,
-.Sq
-(an empty field),
-and
-.Sq D .
-Note that if the
-.Ev IFS
-parameter is set to the
-.Dv NULL
-string, no field splitting is done; if the parameter is unset, the default
-value of space, tab, and newline is used.
-.Pp
-Also, note that the field splitting applies only to the immediate result of
-the substitution.
-Using the previous example, the substitution for $VAR:E
-results in the fields:
-.Sq A ,
-.Sq B ,
-.Sq ,
-and
-.Sq D:E ,
-not
-.Sq A ,
-.Sq B ,
-.Sq ,
-.Sq D ,
-and
-.Sq E .
-This behavior is POSIX compliant, but incompatible with some other shell
-implementations which do field splitting on the word which contained the
-substitution or use
-.Dv IFS
-as a general whitespace delimiter.
-.Pp
-The results of substitution are, unless otherwise specified, also subject to
-file name expansion (see the relevant section below).
-.Pp
-A command substitution is replaced by the output generated by the specified
-command, which is run in a subshell.
-For
-.Pf $( Ns Ar command Ns \&)
-substitutions, normal quoting rules are used when
-.Ar command
-is parsed; however, for the
-.Pf ` Ns Ar command Ns `
-form, a
-.Ql \e
-followed by any of
-.Ql $ ,
-.Ql ` ,
-or
-.Ql \e
-is stripped (a
-.Ql \e
-followed by any other character is unchanged).
-As a special case in command substitutions, a command of the form
-.Pf \*(Lt Ar file
-is interpreted to mean substitute the contents of
-.Ar file .
-Note that
-.Ic $(\*(Lt foo)
-has the same effect as
-.Ic $(cat foo) ,
-but it is carried out more efficiently because no process is started.
-.Pp
-.Sy Note :
-.Pf $( Ns Ar command Ns \&)
-expressions are currently parsed by finding the matching parenthesis,
-regardless of quoting.
-This should be fixed soon.
-.Pp
-Arithmetic substitutions are replaced by the value of the specified expression.
-For example, the command
-.Ic echo $((2+3*4))
-prints 14.
-See
-.Sx Arithmetic expressions
-for a description of an expression.
-.Ss Parameters
-Parameters are shell variables; they can be assigned values and their values
-can be accessed using a parameter substitution.
-A parameter name is either one
-of the special single punctuation or digit character parameters described
-below, or a letter followed by zero or more letters or digits
-.Po
-.Ql _
-counts as a letter
-.Pc .
-Parameter substitutions take the form
-.Pf $ Ns Ar name ,
-.Pf ${ Ns Ar name Ns } ,
-or
-.Sm off
-.Pf ${ Ar name Oo Ar expr Oc }
-.Sm on
-where
-.Ar name
-is a parameter name.
-If substitution is performed on a parameter
-that is not set, a null string is substituted unless the
-.Ic nounset
-option
-.Po
-.Ic set Fl o Ic nounset
-or
-.Ic set Fl u
-.Pc
-is set, in which case an error occurs.
-.Pp
-Parameters can be assigned values in a number of ways.
-First, the shell implicitly sets some parameters like
-.Ql # ,
-.Ql PWD ,
-and
-.Ql $ ;
-this is the only way the special single character parameters are set.
-Second, parameters are imported from the shell's environment at startup.
-Third, parameters can be assigned values on the command line: for example,
-.Ic FOO=bar
-sets the parameter
-.Dq FOO
-to
-.Dq bar ;
-multiple parameter assignments can be given on a single command line and they
-can be followed by a simple-command, in which case the assignments are in
-effect only for the duration of the command (such assignments are also
-exported; see below for the implications of this).
-Note that both the parameter name and the
-.Ql =
-must be unquoted for the shell to recognize a parameter assignment.
-The fourth way of setting a parameter is with the
-.Ic export ,
-.Ic readonly ,
-and
-.Ic typeset
-commands; see their descriptions in the
-.Sx Command execution
-section.
-Fifth,
-.Ic for
-loops set parameters as well as the
-.Ic getopts ,
-.Ic read ,
-and
-.Ic set -A
-commands.
-Lastly, parameters can be assigned values using assignment operators
-inside arithmetic expressions (see
-.Sx Arithmetic expressions
-below) or using the
-.Sm off
-.Pf ${ Ar name No = Ar value No }
-.Sm on
-form of the parameter substitution (see below).
-.Pp
-Parameters with the export attribute (set using the
-.Ic export
-or
-.Ic typeset Fl x
-commands, or by parameter assignments followed by simple commands) are put in
-the environment (see
-.Xr environ 7 )
-of commands run by the shell as
-.Ar name Ns = Ns Ar value
-pairs.
-The order in which parameters appear in the environment of a command is
-unspecified.
-When the shell starts up, it extracts parameters and their values
-from its environment and automatically sets the export attribute for those
-parameters.
-.Pp
-Modifiers can be applied to the
-.Pf ${ Ns Ar name Ns }
-form of parameter substitution:
+Some options have equivalent long names,
+indicated at the start of the description,
+which can be used with the
+.Fl o
+option.
.Bl -tag -width Ds
-.Sm off
-.It ${ Ar name No :- Ar word No }
-.Sm on
-If
-.Ar name
-is set and not
-.Dv NULL ,
-it is substituted; otherwise,
-.Ar word
-is substituted.
-.Sm off
-.It ${ Ar name No :+ Ar word No }
-.Sm on
-If
-.Ar name
-is set and not
-.Dv NULL ,
-.Ar word
-is substituted; otherwise, nothing is substituted.
-.Sm off
-.It ${ Ar name No := Ar word No }
-.Sm on
-If
-.Ar name
-is set and not
-.Dv NULL ,
-it is substituted; otherwise, it is assigned
-.Ar word
-and the resulting value of
-.Ar name
-is substituted.
-.Sm off
-.It ${ Ar name No :? Ar word No }
-.Sm on
-If
-.Ar name
-is set and not
-.Dv NULL ,
-it is substituted; otherwise,
-.Ar word
-is printed on standard error (preceded by
-.Ar name : )
-and an error occurs (normally causing termination of a shell script, function,
-or script sourced using the
-.Sq \&.
-built-in).
-If
-.Ar word
-is omitted, the string
-.Dq parameter null or not set
-is used instead.
-.El
-.Pp
-In the above modifiers, the
-.Ql \&:
-can be omitted, in which case the conditions only depend on
-.Ar name
-being set (as opposed to set and not
-.Dv NULL ) .
-If
-.Ar word
-is needed, parameter, command, arithmetic, and tilde substitution are performed
-on it; if
-.Ar word
-is not needed, it is not evaluated.
-.Pp
-The following forms of parameter substitution can also be used:
-.Pp
-.Bl -tag -width Ds -compact
-.It Pf ${# Ns Ar name Ns \&}
-The number of positional parameters if
-.Ar name
-is
-.Ql * ,
-.Ql @ ,
-or not specified; otherwise the length of the string value of parameter
-.Ar name .
-.Pp
-.It Pf ${# Ns Ar name Ns [*]}
-.It Pf ${# Ns Ar name Ns [@]}
-The number of elements in the array
-.Ar name .
-.Pp
-.Sm off
-.It Xo
-.Pf ${ Ar name
-.Pf # Ar pattern No }
-.Xc
-.It Xo
-.Pf ${ Ar name
-.Pf ## Ar pattern No }
-.Xc
-.Sm on
-If
-.Ar pattern
-matches the beginning of the value of parameter
-.Ar name ,
-the matched text is deleted from the result of substitution.
-A single
-.Ql #
-results in the shortest match, and two
-of them result in the longest match.
-.Pp
-.Sm off
-.It Xo
-.Pf ${ Ar name
-.Pf % Ar pattern No }
-.Xc
-.It Xo
-.Pf ${ Ar name
-.Pf %% Ar pattern No }
-.Xc
-.Sm on
-Like ${..#..} substitution, but it deletes from the end of the value.
-.El
-.Pp
-The following special parameters are implicitly set by the shell and cannot be
-set directly using assignments:
-.Bl -tag -width "1 ... 9"
-.It Ev \&!
-Process ID of the last background process started.
-If no background processes have been started, the parameter is not set.
-.It Ev \&#
-The number of positional parameters ($1, $2, etc.).
-.It Ev \&$
-The PID of the shell, or the PID of the original shell if it is a subshell.
-Do
-.Em NOT
-use this mechanism for generating temporary file names; see
-.Xr mktemp 1
-instead.
-.It Ev -
-The concatenation of the current single letter options (see the
-.Ic set
-command below for a list of options).
-.It Ev \&?
-The exit status of the last non-asynchronous command executed.
-If the last command was killed by a signal,
-.Ic $?\&
-is set to 128 plus the signal number.
-.It Ev 0
-The name of the shell, determined as follows:
-the first argument to
-.Nm
-if it was invoked with the
-.Fl c
-option and arguments were given; otherwise the
-.Ar file
-argument, if it was supplied;
-or else the basename the shell was invoked with (i.e.\&
-.Li argv[0] ) .
-.Ev $0
-is also set to the name of the current script or
-the name of the current function, if it was defined with the
-.Ic function
-keyword (i.e. a Korn shell style function).
-.It Ev 1 No ... Ev 9
-The first nine positional parameters that were supplied to the shell, function,
-or script sourced using the
-.Sq \&.
-built-in.
-Further positional parameters may be accessed using
-.Pf ${ Ar number Ns } .
-.It Ev *
-All positional parameters (except parameter 0) i.e. $1, $2, $3, ...
-If used
-outside of double quotes, parameters are separate words (which are subjected
-to word splitting); if used within double quotes, parameters are separated
-by the first character of the
-.Ev IFS
-parameter (or the empty string if
-.Ev IFS
-is
-.Dv NULL ) .
-.It Ev @
-Same as
-.Ic $* ,
-unless it is used inside double quotes, in which case a separate word is
-generated for each positional parameter.
-If there are no positional parameters, no word is generated.
-.Ic $@
-can be used to access arguments, verbatim, without losing
-.Dv NULL
-arguments or splitting arguments with spaces.
-.El
-.Pp
-The following parameters are set and/or used by the shell:
-.Bl -tag -width "EXECSHELL"
-.It Ev CDPATH
-Search path for the
-.Ic cd
-built-in command.
-It works the same way as
-.Ev PATH
-for those directories not beginning with
-.Ql /
-in
-.Ic cd
-commands.
-Note that if
-.Ev CDPATH
-is set and does not contain
-.Sq \&.
-or contains an empty path, the current directory is not searched.
-Also, the
-.Ic cd
-built-in command will display the resulting directory when a match is found
-in any search path other than the empty path.
-.It Ev COLUMNS
-Set to the number of columns on the terminal or window.
-Currently set to the
-.Dq cols
-value as reported by
-.Xr stty 1
-if that value is non-zero.
-This parameter is used by the
-.Ic set -o
-and
-.Ic kill -l
-commands to format information columns.
-.It Ev ENV
-If this parameter is found to be set after any profile files are executed, the
-expanded value is used as a shell startup file.
-It typically contains function and alias definitions.
-.It Ev ERRNO
-Integer value of the shell's
-.Va errno
-variable.
-It indicates the reason the last system call failed.
-Not yet implemented.
-.It Ev EXECSHELL
-If set, this parameter is assumed to contain the shell that is to be used to
-execute commands that
-.Xr execve 2
-fails to execute and which do not start with a
-.Dq #! Ns Ar shell
-sequence.
-.It Ev FCEDIT
-The editor used by the
-.Ic fc
-command (see below).
-.It Ev FPATH
-Like
-.Ev PATH ,
-but used when an undefined function is executed to locate the file defining the
-function.
-It is also searched when a command can't be found using
-.Ev PATH .
-See
-.Sx Functions
-below for more information.
-.It Ev HOME
-The default directory for the
-.Ic cd
-command and the value substituted for an unqualified
-.Ic ~
-(see
-.Sx Tilde expansion
-below).
-.It Ev IFS
-Internal field separator, used during substitution and by the
-.Ic read
-command, to split values into distinct arguments; normally set to space, tab,
-and newline.
-See
-.Sx Substitution
-above for details.
-.Pp
-.Sy Note :
-This parameter is not imported from the environment when the shell is
-started.
-.It Ev SH_VERSION
-The version of shell and the date the version was created (read-only).
-.It Ev LINENO
-The line number of the function or shell script that is currently being
-executed.
-.It Ev LINES
-Set to the number of lines on the terminal or window.
-.It Ev OLDPWD
-The previous working directory.
-Unset if
-.Ic cd
-has not successfully changed directories since the shell started, or if the
-shell doesn't know where it is.
-.It Ev OPTARG
-When using
-.Ic getopts ,
-it contains the argument for a parsed option, if it requires one.
-.It Ev OPTIND
-The index of the next argument to be processed when using
-.Ic getopts .
-Assigning 1 to this parameter causes
+.It Fl a
+allexport.
+Variable assignments are exported to all child processes
+of the running shell.
+If the assignment precedes a command it does not persist
+after that command has finished running,
+unless the command is a special builtin
+or one of the builtins
.Ic getopts
-to process arguments from the beginning the next time it is invoked.
-.It Ev PATH
-A colon separated list of directories that are searched when looking for
-commands and files sourced using the
-.Sq \&.
-command (see below).
-An empty string resulting from a leading or trailing
-colon, or two adjacent colons, is treated as a
-.Sq \&.
-(the current directory).
-.It Ev POSIXLY_CORRECT
-If set, this parameter causes the
-.Ic posix
-option to be enabled.
-See
-.Sx POSIX mode
-below.
-.It Ev PPID
-The process ID of the shell's parent (read-only).
-.It Ev PS1
-The primary prompt for interactive shells.
-Parameter, command, and arithmetic
-substitutions are performed.
-.Ql \&!
-is replaced with the current command number (see the
-.Ic fc
-command below).
-A literal
-.Ql \&!
-can be put in the prompt by placing
-.Ql !!
-in
-.Ev PS1 .
-The default is
-.Sq $\ \&
-for non-root users,
-.Sq #\ \&
-for root.
-.It Ev PS2
-Secondary prompt string, by default
-.Sq \*(Gt\ \& ,
-used when more input is needed to complete a command.
-.It Ev PS4
-Used to prefix commands that are printed during execution tracing (see the
-.Ic set Fl x
-command below).
-Parameter, command, and arithmetic substitutions are performed
-before it is printed.
-The default is
-.Sq +\ \& .
-.It Ev PWD
-The current working directory.
-May be unset or
-.Dv NULL
-if the shell doesn't know where it is.
-.It Ev REPLY
-Default parameter for the
-.Ic read
-command if no names are given.
-.It Ev TMPDIR
-The directory temporary shell files are created in.
-If this parameter is not
-set, or does not contain the absolute path of a writable directory, temporary
-files are created in
-.Pa /tmp .
-.El
-.Ss Tilde expansion
-Tilde expansion, which is done in parallel with parameter substitution, is done
-on words starting with an unquoted
-.Ql ~ .
-The characters following the tilde, up to the first
-.Ql / ,
-if any, are assumed to be a login name.
-If the login name is empty,
-.Ql + ,
-or
-.Ql - ,
-the value of the
-.Ev HOME ,
-.Ev PWD ,
-or
-.Ev OLDPWD
-parameter is substituted, respectively.
-Otherwise, the password file is
-searched for the login name, and the tilde expression is substituted with the
-user's home directory.
-If the login name is not found in the password file or
-if any quoting or parameter substitution occurs in the login name, no
-substitution is performed.
-.Pp
-In parameter assignments
-(such as those preceding a simple-command or those occurring
-in the arguments of
-.Ic alias ,
-.Ic export ,
-.Ic readonly ,
-and
-.Ic typeset ) ,
-tilde expansion is done after any assignment
-(i.e. after the equals sign)
-or after an unquoted colon
-.Pq Sq \&: ;
-login names are also delimited by colons.
-.Pp
-The home directory of previously expanded login names are cached and re-used.
-The
-.Ic alias -d
-command may be used to list, change, and add to this cache (e.g.\&
-.Ic alias -d fac=/usr/local/facilities; cd ~fac/bin ) .
-.Ss File name patterns
-A file name pattern is a word containing one or more unquoted
-.Ql \&? ,
-.Ql * ,
-.Ql + ,
-.Ql @ ,
-or
-.Ql \&!
-characters or
-.Dq [..]
-sequences.
-The shell replaces file
-name patterns with the sorted names of all the files that match the pattern
-(if no files match, the word is left unchanged).
-The pattern elements have the following meaning:
-.Bl -tag -width Ds
-.It \&?
-Matches any single character.
-.It \&*
-Matches any sequence of characters.
-.It [..]
-Matches any of the characters inside the brackets.
-Ranges of characters can be
-specified by separating two characters by a
-.Ql -
-(e.g.\&
-.Dq [a0-9]
-matches the letter
-.Sq a
-or any digit).
-In order to represent itself, a
-.Ql -
-must either be quoted or the first or last character in the character list.
-Similarly, a
-.Ql \&]
-must be quoted or the first character in the list if it is to represent itself
-instead of the end of the list.
-Also, a
-.Ql \&!
-appearing at the start of the list has special meaning (see below), so to
-represent itself it must be quoted or appear later in the list.
-.Pp
-Within a bracket expression, the name of a
-.Em character class
-enclosed in
-.Sq [:
-and
-.Sq :]
-stands for the list of all characters belonging to that class.
-Supported character classes:
-.Bd -literal -offset indent
-alnum cntrl lower space
-alpha digit print upper
-blank graph punct xdigit
-.Ed
-.Pp
-These match characters using the macros specified in
-.Xr isalnum 3 ,
-.Xr isalpha 3 ,
-and so on.
-A character class may not be used as an endpoint of a range.
-.It [!..]
-Like [..],
-except it matches any character not inside the brackets.
-.Sm off
-.It *( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
-.Sm on
-Matches any string of characters that matches zero or more occurrences of the
-specified patterns.
-Example: The pattern
-.Ic *(foo|bar)
-matches the strings
-.Dq ,
-.Dq foo ,
-.Dq bar ,
-.Dq foobarfoo ,
-etc.
-.Sm off
-.It +( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
-.Sm on
-Matches any string of characters that matches one or more occurrences of the
-specified patterns.
-Example: The pattern
-.Ic +(foo|bar)
-matches the strings
-.Dq foo ,
-.Dq bar ,
-.Dq foobar ,
-etc.
-.Sm off
-.It ?( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
-.Sm on
-Matches the empty string or a string that matches one of the specified
-patterns.
-Example: The pattern
-.Ic ?(foo|bar)
-only matches the strings
-.Dq ,
-.Dq foo ,
-and
-.Dq bar .
-.Sm off
-.It @( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
-.Sm on
-Matches a string that matches one of the specified patterns.
-Example: The pattern
-.Ic @(foo|bar)
-only matches the strings
-.Dq foo
-and
-.Dq bar .
-.Sm off
-.It !( Ar pattern\*(Ba No ...\*(Ba Ar pattern )
-.Sm on
-Matches any string that does not match one of the specified patterns.
-Examples: The pattern
-.Ic !(foo|bar)
-matches all strings except
-.Dq foo
-and
-.Dq bar ;
-the pattern
-.Ic !(*)
-matches no strings; the pattern
-.Ic !(?)*\&
-matches all strings (think about it).
-.El
-.Pp
-Note that
-.Nm pdksh
-currently never matches
-.Sq \&.
-and
-.Sq .. ,
-but the original
-.Nm ksh ,
-Bourne
-.Nm sh ,
-and bash do, so this may have to change (too bad).
-.Pp
-Note that none of the above pattern elements match either a period
-.Pq Sq \&.
-at the start of a file name or a slash
-.Pq Sq / ,
-even if they are explicitly used in a [..] sequence; also, the names
-.Sq \&.
-and
-.Sq ..
-are never matched, even by the pattern
-.Sq .* .
-.Pp
-If the
-.Ic markdirs
-option is set, any directories that result from file name generation are marked
-with a trailing
-.Ql / .
-.Ss Input/output redirection
-When a command is executed, its standard input, standard output, and standard
-error (file descriptors 0, 1, and 2, respectively) are normally inherited from
-the shell.
-Three exceptions to this are commands in pipelines, for which
-standard input and/or standard output are those set up by the pipeline,
-asynchronous commands created when job control is disabled, for which standard
-input is initially set to be from
-.Pa /dev/null ,
-and commands for which any of the following redirections have been specified:
-.Bl -tag -width Ds
-.It \*(Gt Ar file
-Standard output is redirected to
-.Ar file .
-If
-.Ar file
-does not exist, it is created; if it does exist, is a regular file, and the
-.Ic noclobber
-option is set, an error occurs; otherwise, the file is truncated.
-Note that this means the command
-.Ic cmd \*(Lt foo \*(Gt foo
-will open
-.Ar foo
-for reading and then truncate it when it opens it for writing, before
-.Ar cmd
-gets a chance to actually read
-.Ar foo .
-.It \*(Gt\*(Ba Ar file
-Same as
-.Ic \*(Gt ,
-except the file is truncated, even if the
-.Ic noclobber
-option is set.
-.It \*(Gt\*(Gt Ar file
-Same as
-.Ic \*(Gt ,
-except if
-.Ar file
-exists it is appended to instead of being truncated.
-Also, the file is opened
-in append mode, so writes always go to the end of the file (see
-.Xr open 2 ) .
-.It \*(Lt Ar file
-Standard input is redirected from
-.Ar file ,
-which is opened for reading.
-.It \*(Lt\*(Gt Ar file
-Same as
-.Ic \*(Lt ,
-except the file is opened for reading and writing.
-.It \*(Lt\*(Lt Ar marker
-After reading the command line containing this kind of redirection (called a
-.Dq here document ) ,
-the shell copies lines from the command source into a temporary file until a
-line matching
-.Ar marker
-is read.
-When the command is executed, standard input is redirected from the
-temporary file.
-If
-.Ar marker
-contains no quoted characters, the contents of the temporary file are processed
-as if enclosed in double quotes each time the command is executed, so
-parameter, command, and arithmetic substitutions are performed, along with
-backslash
-.Pq Sq \e
-escapes for
-.Ql $ ,
-.Ql ` ,
-.Ql \e ,
-and
-.Ql \enewline .
-If multiple here documents are used on the same command line, they are saved in
-order.
-.It \*(Lt\*(Lt- Ar marker
-Same as
-.Ic \*(Lt\*(Lt ,
-except leading tabs are stripped from lines in the here document.
-.It \*(Lt& Ar fd
-Standard input is duplicated from file descriptor
-.Ar fd .
-.Ar fd
-can be a single digit, indicating the number of an existing file descriptor;
-the letter
-.Ql p ,
-indicating the file descriptor associated with the output of the current
-co-process; or the character
-.Ql - ,
-indicating standard input is to be closed.
-.It \*(Gt& Ar fd
-Same as
-.Ic \*(Lt& ,
-except the operation is done on standard output.
-.El
-.Pp
-In any of the above redirections, the file descriptor that is redirected
-(i.e. standard input or standard output)
-can be explicitly given by preceding the
-redirection with a single digit.
-Parameter, command, and arithmetic
-substitutions, tilde substitutions, and (if the shell is interactive)
-file name generation are all performed on the
-.Ar file ,
-.Ar marker ,
-and
-.Ar fd
-arguments of redirections.
-Note, however, that the results of any file name
-generation are only used if a single file is matched; if multiple files match,
-the word with the expanded file name generation characters is used.
-Note
-that in restricted shells, redirections which can create files cannot be used.
-.Pp
-For simple-commands, redirections may appear anywhere in the command; for
-compound-commands
-.Po
-.Ic if
-statements, etc.
-.Pc ,
-any redirections must appear at the end.
-Redirections are processed after
-pipelines are created and in the order they are given, so the following
-will print an error with a line number prepended to it:
-.Pp
-.D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt /dev/null \*(Ba cat -n
-.Ss Arithmetic expressions
-Integer arithmetic expressions can be used with the
-.Ic let
-command, inside $((..)) expressions, inside array references (e.g.\&
-.Ar name Ns Bq Ar expr ) ,
-as numeric arguments to the
-.Ic test
-command, and as the value of an assignment to an integer parameter.
-.Pp
-Expressions may contain alpha-numeric parameter identifiers, array references,
-and integer constants and may be combined with the following C operators
-(listed and grouped in increasing order of precedence):
-.Pp
-Unary operators:
-.Bd -literal -offset indent
-+ - ! ~ ++ --
-.Ed
-.Pp
-Binary operators:
-.Bd -literal -offset indent
-,
-= *= /= %= += -= \*(Lt\*(Lt= \*(Gt\*(Gt= &= ^= \*(Ba=
-\*(Ba\*(Ba
-&&
-\*(Ba
-^
-&
-== !=
-\*(Lt \*(Lt= \*(Gt= \*(Gt
-\*(Lt\*(Lt \*(Gt\*(Gt
-+ -
-* / %
-.Ed
-.Pp
-Ternary operators:
-.Bd -literal -offset indent
-?: (precedence is immediately higher than assignment)
-.Ed
-.Pp
-Grouping operators:
-.Bd -literal -offset indent
-( )
-.Ed
-.Pp
-A parameter that is NULL or unset evaluates to 0.
-Integer constants may be specified with arbitrary bases using the notation
-.Ar base Ns # Ns Ar number ,
-where
-.Ar base
-is a decimal integer specifying the base, and
-.Ar number
-is a number in the specified base.
-Additionally,
-integers may be prefixed with
-.Sq 0X
or
-.Sq 0x
-(specifying base 16)
-or
-.Sq 0
-(base 8)
-in all forms of arithmetic expressions,
-except as numeric arguments to the
-.Ic test
-command.
-.Pp
-The operators are evaluated as follows:
-.Bl -tag -width Ds -offset indent
-.It unary +
-Result is the argument (included for completeness).
-.It unary -
-Negation.
-.It \&!
-Logical NOT;
-the result is 1 if argument is zero, 0 if not.
-.It ~
-Arithmetic (bit-wise) NOT.
-.It ++
-Increment; must be applied to a parameter (not a literal or other expression).
-The parameter is incremented by 1.
-When used as a prefix operator, the result
-is the incremented value of the parameter; when used as a postfix operator, the
-result is the original value of the parameter.
-.It --
-Similar to
-.Ic ++ ,
-except the parameter is decremented by 1.
-.It \&,
-Separates two arithmetic expressions; the left-hand side is evaluated first,
-then the right.
-The result is the value of the expression on the right-hand side.
-.It =
-Assignment; the variable on the left is set to the value on the right.
-.It Xo
-.No *= /= += -= \*(Lt\*(Lt=
-.No \*(Gt\*(Gt= &= ^= \*(Ba=
-.Xc
-Assignment operators.
-.Sm off
-.Ao Ar var Ac Xo
-.Aq Ar op
-.No = Aq Ar expr
-.Xc
-.Sm on
-is the same as
-.Sm off
-.Ao Ar var Ac Xo
-.No = Aq Ar var
-.Aq Ar op
-.Aq Ar expr ,
-.Xc
-.Sm on
-with any operator precedence in
-.Aq Ar expr
-preserved.
-For example,
-.Dq var1 *= 5 + 3
-is the same as specifying
-.Dq var1 = var1 * (5 + 3) .
-.It \*(Ba\*(Ba
-Logical OR;
-the result is 1 if either argument is non-zero, 0 if not.
-The right argument is evaluated only if the left argument is zero.
-.It &&
-Logical AND;
-the result is 1 if both arguments are non-zero, 0 if not.
-The right argument is evaluated only if the left argument is non-zero.
-.It \*(Ba
-Arithmetic (bit-wise) OR.
-.It ^
-Arithmetic (bit-wise) XOR
-(exclusive-OR).
-.It &
-Arithmetic (bit-wise) AND.
-.It ==
-Equal; the result is 1 if both arguments are equal, 0 if not.
-.It !=
-Not equal; the result is 0 if both arguments are equal, 1 if not.
-.It \*(Lt
-Less than; the result is 1 if the left argument is less than the right, 0 if
-not.
-.It \*(Lt= \*(Gt= \*(Gt
-Less than or equal, greater than or equal, greater than.
-See
-.Ic \*(Lt .
-.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 + - * /
-Addition, subtraction, multiplication, and division.
-.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 :
-.Aq Ar arg3
-.Sm on
-.Xc
-If
-.Aq Ar arg1
-is non-zero, the result is
-.Aq Ar arg2 ;
-otherwise the result is
-.Aq Ar arg3 .
-.El
-.Ss Functions
-Functions are defined using either Korn shell
-.Ic function Ar function-name
-syntax or the Bourne/POSIX shell
-.Ar function-name Ns ()
-syntax (see below for the difference between the two forms).
-Functions are like
-.Li .-scripts
-(i.e. scripts sourced using the
-.Sq \&.
-built-in)
-in that they are executed in the current environment.
-However, unlike
-.Li .-scripts ,
-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
-.Ev PATH
-is searched.
-.Pp
-An existing function may be deleted using
-.Ic unset Fl f Ar function-name .
-A list of functions can be obtained using
-.Ic typeset +f
-and the function definitions can be listed using
-.Ic typeset -f .
-The
-.Ic autoload
-command (which is an alias for
-.Ic typeset -fu )
-may be used to create undefined functions: when an undefined function is
-executed, the shell searches the path specified in the
-.Ev FPATH
-parameter for a file with the same name as the function, which, if found, is
-read and executed.
-If after executing the file the named function is found to
-be defined, the function is executed; otherwise, the normal command search is
-continued (i.e. the shell searches the regular built-in command table and
-.Ev PATH ) .
-Note that if a command is not found using
-.Ev PATH ,
-an attempt is made to autoload a function using
-.Ev FPATH
-(this is an undocumented feature of the original Korn shell).
-.Pp
-Functions can have two attributes,
-.Dq trace
-and
-.Dq export ,
-which can be set with
-.Ic typeset -ft
+.Ic read
+makes the assignment.
+.It Fl b
+notify.
+The user is given notice asynchronously when background jobs complete.
+.It Fl C
+noclobber.
+Do not permit the redirection operator
+.Pq Sq >
+to clobber (overwrite) existing files.
+.It Fl e
+errexit.
+Exit the shell immediately should an error occur or a command fail.
+For pipelines and
+.Cm &&
+and
+.Cm ||
+constructs, only exit if the last component fails.
+errexit is ignored for
+.Ic while ,
+.Ic until ,
+.Ic if ,
and
-.Ic typeset -fx ,
-respectively.
-When a traced function is executed, the shell's
-.Ic xtrace
-option is turned on for the function's duration; otherwise, the
-.Ic xtrace
-option is turned off.
-The
-.Dq export
-attribute of functions is currently not used.
-In the original Korn shell,
-exported functions are visible to shell scripts that are executed.
-.Pp
-Since functions are executed in the current shell environment, parameter
-assignments made inside functions are visible after the function completes.
-If this is not the desired effect, the
-.Ic typeset
-command can be used inside a function to create a local parameter.
-Note that special parameters (e.g.\&
-.Ic \&$$ , $! )
-can't be scoped in this way.
-.Pp
-The exit status of a function is that of the last command executed in the
-function.
-A function can be made to finish immediately using the
-.Ic return
-command; this may also be used to explicitly specify the exit status.
-.Pp
-Functions defined with the
-.Ic function
-reserved word are treated differently in the following ways from functions
-defined with the
-.Ic ()
-notation:
-.Bl -bullet
-.It
-The $0 parameter is set to the name of the function
-(Bourne-style functions leave $0 untouched).
-.It
-Parameter assignments preceding function calls are not kept in the shell
-environment (executing Bourne-style functions will keep assignments).
-.It
-.Ev OPTIND
-is saved/reset and restored on entry and exit from the function so
-.Ic getopts
-can be used properly both inside and outside the function (Bourne-style
-functions leave
-.Ev OPTIND
-untouched, so using
-.Ic getopts
-inside a function interferes with using
-.Ic getopts
-outside the function).
-.El
-.Pp
-In the future, the following differences will also be added:
-.Bl -bullet
-.It
-A separate trap/signal environment will be used during the execution of
-functions.
-This will mean that traps set inside a function will not affect the
-shell's traps and signals that are not ignored in the shell (but may be
-trapped) will have their default effect in a function.
-.It
-The EXIT trap, if set in a function, will be executed after the function
-returns.
-.El
-.Ss POSIX mode
-The shell is intended to be POSIX compliant;
-however, in some cases, POSIX behaviour is contrary either to
-the original Korn shell behaviour or to user convenience.
-How the shell behaves in these cases is determined by the state of the
-.Ic posix
-option
-.Pq Ic set -o posix .
-If it is on, the POSIX behaviour is followed; otherwise, it is not.
-The
-.Ic posix
-option is set automatically when the shell starts up if the environment
-contains the
-.Ev POSIXLY_CORRECT
-parameter.
-The shell can also be compiled so that it is in POSIX mode by default;
-however, this is usually not desirable.
-.Pp
-The following is a list of things that are affected by the state of the
-.Ic posix
-option:
-.Bl -bullet
-.It
-Reading of
-.Ev $ENV :
-if not in
-.Ic posix
-mode, the
-.Ev ENV
-parameter is not expanded and included when the shell starts.
-.It
-Occurrences of
-.Ic \e\&"
-inside double quoted
-.Ic `..`
-command substitutions.
-In POSIX mode, the
-.Ic \e\&"
-is interpreted when the command is interpreted;
-in non-POSIX mode,
-the backslash is stripped before the command substitution is interpreted.
-For example,
-.Ic echo \&"`echo \e\&"hi\e\&"`\&"
-produces
-.Dq \&"hi\&"
-in POSIX mode,
-.Dq hi
-in non-POSIX mode.
-To avoid problems, use the
-.Ic $(...)\&
-form of command substitution.
-.It
-.Ic kill -l
-output.
-In POSIX mode, only signal names are listed (in a single line);
-in non-POSIX mode,
-signal numbers, names, and descriptions are printed (in columns).
-In the future, a new option
-.Pq Fl v No perhaps
-will be added to distinguish the two behaviours.
-.It
-.Ic echo
-options.
-In POSIX mode,
-.Fl e
+.Ic elif
+lists and pipelines beginning
+.Sq !\& .
+.It Fl f
+noglob.
+Do not expand file name patterns.
+.It Fl h
+When a utility is first executed,
+hash (record) its location
+so that future invocations do not need to search for it.
+Builtins are not hashed, regardless of whether this option is set or not.
+This option is set by default for non-interactive shells.
+.It Fl i
+Enable behaviour convenient for an interactive shell.
+This option is set by default
+if the session is attached to a terminal.
+.It Fl m
+monitor.
+Fully enable job control:
+enable the
+.Ic bg
and
-.Fl E
-are not treated as options, but printed like other arguments;
-in non-POSIX mode, these options control the interpretation
-of backslash sequences.
-.It
.Ic fg
-exit status.
-In POSIX mode, the exit status is 0 if no errors occur;
-in non-POSIX mode, the exit status is that of the last foregrounded job.
-.It
-.Ic getopts .
-In POSIX mode, options must start with a
-.Ql - ;
-in non-POSIX mode, options can start with either
-.Ql -
-or
-.Ql + .
-.It
-.Ic set - .
-In POSIX mode, this does not clear the
-.Ic verbose
-or
-.Ic xtrace
-options; in non-POSIX mode, it does.
-.It
-.Ic set
-exit status.
-In POSIX mode, the exit status of
-.Ic set
-is 0 if there are no errors;
-in non-POSIX mode, the exit status is that of any
-command substitutions performed in generating the
-.Ic set
-command.
-For example,
-.Ic set -- `false`; echo $?\&
-prints 0 in POSIX mode, 1 in non-POSIX mode.
-This construct is used in most shell scripts that use the old
-.Xr getopt 1
-command.
-.It
-Argument expansion of the
-.Ic alias ,
-.Ic export ,
-.Ic readonly ,
-and
-.Ic typeset
-commands.
-In POSIX mode, normal argument expansion is done; in non-POSIX mode,
-field splitting, file globbing, and (normal) tilde expansion
-are turned off, while assignment tilde expansion is turned on.
-.It
-Signal specification.
-In POSIX mode, signals can be specified as digits, only
-if signal numbers match POSIX values
-(i.e. HUP=1, INT=2, QUIT=3, ABRT=6, KILL=9, ALRM=14, and TERM=15);
-in non-POSIX mode, signals can always be digits.
-.It
-Alias expansion.
-In POSIX mode, alias expansion is only carried out when reading command words;
-in non-POSIX mode, alias expansion is carried out on any
-word following an alias that ended in a space.
-For example, the following
-.Ic for
-loop uses parameter
-.Sq i
-in POSIX mode and
-.Sq j
-in non-POSIX mode:
-.Bd -literal -offset indent
-alias a='for ' i='j'
-a i in 1 2; do echo i=$i j=$j; done
-.Ed
-.It
-.Ic test .
-In POSIX mode, the expression
-.Sq Fl t
-(preceded by some number of
-.Sq \&!
-arguments) is always true as it is a non-zero length string;
-in non-POSIX mode, it tests if file descriptor 1 is a
-.Xr tty 4
-(i.e. the
-.Ar fd
-argument to the
-.Fl t
-test may be left out and defaults to 1).
+builtins;
+report completion status when jobs finish;
+report when a foreground process stops;
+and report when a job changes status.
+The processes of a job share their own process group.
+This option is set by default for interactive shells.
+.It Fl n
+noexec.
+Read commands but do not execute them \(en
+useful for checking syntax errors in scripts.
+This option is ignored for interactive shells.
+.It Fl o Ar option
+Specify an option by its long name.
+Those described below have no equivalent option letter:
+.Pp
+.Bl -tag -width "ignoreeof" -offset 3n -compact
+.It ignoreeof
+Ignore an end-of-file
+.Pq Sq ^D .
+EOF normally logs a user out,
+so setting this can prevent accidental logouts
+(the user will need to explicitly use the
+.Ic exit
+command).
+.It nolog
+Do not enter function definitions into command history.
+.It vi
+Enable
+.Xr vi 1
+command line editing.
.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
-.Ev PATH
-parameter.
-The checks are made in the above order.
-Special built-in commands differ from other commands in that the
-.Ev PATH
-parameter is not used to find them, an error during their execution can
-cause a non-interactive shell to exit, and parameter assignments that are
-specified before the command are kept after the command completes.
-Just to confuse things, if the
-.Ic posix
-option is turned off (see the
-.Ic set
-command below), some special commands are very special in that no field
-splitting, file globbing, nor tilde expansion is performed
-on arguments that look like assignments.
-Regular built-in commands are different only in that the
-.Ev PATH
-parameter is not used to find them.
-.Pp
-The original
-.Nm ksh
-and POSIX differ somewhat in which commands are considered
-special or regular:
-.Pp
-POSIX special commands
-.Pp
-.Ic \&. , \&: , break , continue ,
+.It Fl u
+nounset.
+If a command references an unset parameter,
+write an error to standard output instead of executing the command.
+This option is ignored for the special parameters
+.Sq *
+and
+.Sq @ .
+If the shell is not interactive,
+immediately exit.
+.It Fl v
+verbose.
+Write input to standard error after reading it.
+.It Fl x
+xtrace.
+Write a trace for each command to standard error after expanding it,
+and before executing it.
+.El
+.Sh BUILTINS
+The shell has a number of
+.Em built-ins
+available:
+utilities that are included as part of the shell.
+The shell does not need to search for them
+and can execute them directly.
+.Pp
+A number of built-ins are special in that
+a syntax error can cause a running shell to abort,
+and, after the built-in completes,
+variable assignments remain in the current environment.
+The following built-ins are special:
+.Ic .\& , :\& , break , continue ,
.Ic eval , exec , exit , export ,
.Ic readonly , return , set , shift ,
-.Ic times , trap , unset
-.Pp
-Additional
-.Nm
-special commands
-.Pp
-.Ic builtin , typeset
-.Pp
-Very special commands
-.Pq when POSIX mode is off
-.Pp
-.Ic alias , readonly , set , typeset
-.Pp
-POSIX regular commands
-.Pp
-.Ic alias , bg , cd , command ,
-.Ic false , fc , fg , getopts ,
-.Ic jobs , kill , pwd , read ,
-.Ic true , umask , unalias , wait
-.Pp
-Additional
-.Nm
-regular commands
-.Pp
-.Ic \&[ , echo , let , print ,
-.Ic pwd , test , ulimit , whence
+.Ic times , trap ,
+and
+.Ic unset .
.Pp
-In the future, the additional
+The built-ins available to
.Nm
-special and regular commands may be treated
-differently from the POSIX special and regular commands.
-.Pp
-Once the type of command has been determined, any command-line parameter
-assignments are performed and exported for the duration of the command.
-.Pp
-The following describes the special and regular built-in commands:
-.Pp
-.Bl -tag -width Ds -compact
-.It Ic \&. Ar file Op Ar arg ...
+are listed below.
+Unless otherwise indicated,
+they exit 0 on success,
+and >0 if an error occurs.
+.Bl -ohang
+.It Ic .\& Ar file
Execute the commands in
-.Ar file
+.Ar file ,
in the current environment.
-The file is searched for in the directories of
-.Ev PATH .
-If arguments are given, the positional parameters may be used to access them
-while
-.Ar file
-is being executed.
-If no arguments are given, the positional parameters are
-those of the environment the command is used in.
-.Pp
-.It Ic \&: Op Ar ...
-The null command.
-Exit status is set to zero.
-.Pp
-.It Xo Ic alias
-.Oo Fl d \*(Ba t Oo Fl r Oc \*(Ba
-.Cm +-x Oc
-.Op Fl p
-.Op Cm +
-.Oo Ar name
-.Op Ns = Ns Ar value
-.Ar ... Oc
-.Xc
-Without arguments,
-.Ic alias
-lists all aliases.
-For any name without a value, the existing alias is listed.
-Any name with a value defines an alias (see
-.Sx Aliases
-above).
-.Pp
-When listing aliases, one of two formats is used.
-Normally, aliases are listed as
-.Ar name Ns = Ns Ar value ,
-where
-.Ar value
-is quoted.
-If options were preceded with
-.Ql + ,
-or a lone
-.Ql +
-is given on the command line, only
-.Ar name
-is printed.
-.Pp
-The
-.Fl d
-option causes directory aliases, which are used in tilde expansion, to be
-listed or set (see
-.Sx Tilde expansion
-above).
-.Pp
-If the
-.Fl p
-option is used, each alias is prefixed with the string
-.Dq alias\ \& .
-.Pp
-The
-.Fl t
-option indicates that tracked aliases are to be listed/set (values specified on
-the command line are ignored for tracked aliases).
-The
-.Fl r
-option indicates that all tracked aliases are to be reset.
-.Pp
+The actual file need not be executable,
+and its location is determined by searching
+.Ev PATH
+if there are no slashes in the filename.
+The exit status is that of the last command returned,
+or zero if no commands were executed.
+If no readable file can be found,
+a non-interactive shell will abort;
+an interactive shell writes an error message
+and returns a non-zero exit status.
+.It Ic :\& Op Ar arg ...
The
-.Fl x
-option sets
-.Pq Ic +x No clears
-the export attribute of an alias, or, if no names are given, lists the aliases
-with the export attribute (exporting an alias has no effect).
-.Pp
-.It Ic bg Op Ar job ...
-Resume the specified stopped job(s) in the background.
-If no jobs are specified,
-.Ic %+
-is assumed.
-See
-.Sx Job control
-below for more information.
-.Pp
-.It Ic break Op Ar level
-Exit the
-.Ar level Ns th
-inner-most
-.Ic for ,
-.Ic until ,
-or
-.Ic while
-loop.
-.Ar level
-defaults to 1.
-.Pp
-.It Ic builtin Ar command Op Ar arg ...
-Execute the built-in command
-.Ar command .
-.Pp
-.It Xo
-.Ic cd
-.Op Fl LP
-.Op Ar dir
-.Xc
-Set the working directory to
-.Ar dir .
-If the parameter
-.Ev CDPATH
-is set, it lists the search path for the directory containing
-.Ar dir .
-A
-.Dv NULL
-path means the current directory.
+.Ic :\&
+command does nothing \(en
+it is a placeholder for when a command is required.
+Its exit status is always zero.
+.It Ic alias Op Ar name Ns Oo = Ns Ar value Oc Ar ...
+Define an alias
+.Ar name
+to
+.Ar value ;
+when the shell encounters a command name that is an alias,
+its value is substituted.
If
-.Ar dir
-is found in any component of the
-.Ev CDPATH
-search path other than the
-.Dv NULL
-path, the name of the new working directory will be written to standard output.
+.Ar value
+ends in a blank,
+the next word is checked for alias substitution too.
+If only a
+.Ar name
+is specified,
+display the value of that alias;
+if no arguments are given,
+list all aliases and their values.
+Aliases are visible in the current environment and that of subshells,
+but not by the parent process of the current shell
+or by utilities invoked by it.
+.It Ic bg Op Ar id ...
+Select a job by
+.Ar id
+(see the
+.Ic jobs
+command, below)
+to run in the background.
+The default job is
+.Qq %+ .
+.It Ic break Op Ar n
+Exit from the innermost
+.Ic for , while ,
+or
+.Ic until
+loop,
+or from loop level
+.Ar n .
+.It Ic cd Oo Fl L | P Oc Op Ar dir
+Change the current working directory to
+.Ar dir ,
+or
+.Ev $HOME
+by default.
If
.Ar dir
-is missing, the home directory
-.Ev HOME
-is used.
+is set to
+.Sq - ,
+change to the previous working directory and
+print the (now current) working directory.
If
.Ar dir
-is
-.Ql - ,
-the previous working directory is used (see the
-.Ev OLDPWD
-parameter).
-.Pp
-If the
-.Fl L
-option (logical path) is used or if the
-.Ic physical
-option isn't set (see the
-.Ic set
-command below), references to
-.Sq ..
-in
-.Ar dir
-are relative to the path used to get to the directory.
-If the
-.Fl P
-option (physical path) is used or if the
-.Ic physical
-option is set,
-.Sq ..
-is relative to the filesystem directory tree.
-The
-.Ev PWD
-and
-.Ev OLDPWD
-parameters are updated to reflect the current and old working directory,
-respectively.
+does not begin with a slash or dot,
+.Ev CDPATH
+is searched for the directory.
.Pp
-.It Xo
+The options to the
.Ic cd
-.Op Fl LP
-.Ar old new
-.Xc
-The string
-.Ar new
-is substituted for
-.Ar old
-in the current directory, and the shell attempts to change to the new
-directory.
+command are as follows:
+.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl L
+Do not resolve symbolic links before processing
+.Qq ..
+components.
+.It Fl P
+Resolve symbolic links before processing
+.Qq ..
+components.
+.El
+.It Ic command Oo Fl p | V | v Oc Ar command Op Ar arg ...
+Invoke
+.Ar command
+(and any optional arguments),
+overriding any functions with the same name,
+and without any of the properties that special built-ins have.
.Pp
-.It Xo
-.Ic command
-.Op Fl p
-.Ar cmd
-.Op Ar arg ...
-.Xc
-.Ar cmd
-is executed exactly as if
+The options to
.Ic command
-had not been specified, with two exceptions:
-firstly,
-.Ar cmd
-cannot be a shell function;
-and secondly, special built-in commands lose their specialness
-(i.e. redirection and utility errors do not cause the shell to
-exit, and command assignments are not permanent).
-.Pp
-If the
-.Fl p
-option is given, a default search path is used instead of the current value of
-.Ev PATH
-(the actual value of the default path is system dependent: on
-POSIX-ish systems, it is the value returned by
-.Ic getconf CS_PATH ) .
-.Pp
-.It Ic continue Op Ar level
-Jumps to the beginning of the
-.Ar level Ns th
-inner-most
-.Ic for ,
-.Ic until ,
-or
-.Ic while
-loop.
-.Ar level
-defaults to 1.
+are as follows:
.Pp
-.It Xo
-.Ic echo
-.Op Fl Een
-.Op Ar arg ...
-.Xc
-Prints its arguments (separated by spaces) followed by a newline, to the
-standard output.
-The newline is suppressed if any of the arguments contain the
-backslash sequence
-.Ql \ec .
-See the
-.Ic print
-command below for a list of other backslash sequences that are recognized.
-.Pp
-The options are provided for compatibility with
-.Bx
-shell scripts.
-The
-.Fl n
-option suppresses the trailing newline,
-.Fl e
-enables backslash interpretation (a no-op, since this is normally done), and
-.Fl E
-suppresses backslash interpretation.
-If the
-.Ic posix
-option is set, only the first argument is treated as an option, and only
-if it is exactly
-.Dq -n .
-.Pp
-.It Ic eval Ar command ...
-The arguments are concatenated (with spaces between them) to form a single
-string which the shell then parses and executes in the current environment.
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl p
+Use a default value for
+.Ev PATH
+to search for the command.
+.It Fl V
+Do not invoke
+.Ar command ,
+but identify how the shell will interpret it
+(such as a function or special built-in).
+.It Fl v
+Do not invoke
+.Ar command ,
+but identify the pathname the shell will use to run it.
+.El
.Pp
-.It Xo
+The exit status is that of
+.Ar command ,
+or 126 if
+.Ar command
+could not be invoked,
+or 127 if an error occurred in
+.Ic command
+itself or
+.Ar command
+could not be found.
+If the options
+.Fl V
+or
+.Fl v
+are given,
+the exit status is 0 on success,
+or >0 if an error occurs.
+.It Ic continue Op Ar n
+Go directly to the next iteration of the innermost
+.Ic for , while ,
+or
+.Ic until
+loop,
+or from loop level
+.Ar n .
+.It Ic eval Op Ar arg ...
+Concatenate the arguments given
+and interpret them as a command.
+The exit status is that of the resulting command,
+zero if no arguments are given,
+or >0 if the resulting command could not be correctly parsed.
+.It Ic exec Op Ar command Op Ar arg ...
+Replace the shell with
+.Ar command
+(and any optional arguments),
+without creating a new process.
+The exit status is that of
+.Ar command ,
+or 126 if
+.Ar command
+could not be invoked,
+or 127 if
+.Ar command
+could not be found.
+If no command is given but a redirection happens,
+the exit status is 1\(en125;
+otherwise
.Ic exec
-.Op Ar command Op Ar arg ...
-.Xc
-The command is executed without forking, replacing the shell process.
-.Pp
-If no command is given except for I/O redirection, the I/O redirection is
-permanent and the shell is
-not replaced.
-Any file descriptors which are opened or
-.Xr dup 2 Ns 'd
-in this way are made available to other executed commands (note that the Korn
-shell differs here: it does not pass on file descriptors greater than 2).
-.Pp
-.It Ic exit Op Ar status
-The shell exits with the specified exit status.
-If
-.Ar status
-is not specified, the exit status is the current value of the
-.Ic $?\&
-parameter.
+returns 0.
+.It Ic exit Op Ar n
+Exit the shell with exit status
+.Ar n ,
+or that of the last command executed.
+.It Ic export Oo Fl p Oc Ar name Ns Oo = Ns Ar value Oc Ar ...
+Make the variable
+.Ar name
+visible to subsequently run commands,
+optionally setting it to
+.Ar value .
.Pp
-.It Xo
-.Ic export
-.Op Fl p
-.Op Ar parameter Ns Op = Ns Ar value
-.Xc
-Sets the export attribute of the named parameters.
-Exported parameters are passed in the environment to executed commands.
-If values are specified, the named parameters are also assigned.
-.Pp
-If no parameters are specified, the names of all parameters with the export
-attribute are printed one per line, unless the
-.Fl p
-option is used, in which case
+The options to the
.Ic export
-commands defining all exported parameters, including their values, are printed.
+command are as follows:
.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl p
+List all exported variables in a manner that can be reinput to the shell.
+.El
.It Ic false
-A command that exits with a non-zero status.
-.Pp
+Return a false (non-zero) value.
.It Xo
.Ic fc
-.Cm -e - \*(Ba Fl s
-.Op Fl g
-.Op Ar old Ns = Ns Ar new
-.Op Ar prefix
+.Op Fl lnr
+.Op Fl e Ar editor
+.Op Fl s Op Ar old Ns = Ns Ar new
+.Op Ar first Op Ar last
.Xc
-Re-execute the selected command (the previous command by default) after
-performing the optional substitution of
-.Ar old
-with
-.Ar new .
-If
-.Fl g
-is specified, all occurrences of
+Edit commands from command history using
+.Xr ed 1 .
+After editing,
+the new commands are executed by the shell.
+.Pp
+The options to the
+.Ic fc
+command are as follows:
+.Pp
+.Bl -tag -width "-s [old=new]" -offset 3n -compact
+.It Fl e Ar editor
+Edit commands using
+.Ar editor .
+See also
+.Ev FCEDIT .
+.It Fl l
+List the command history.
+.It Fl ln
+List the command history without command numbers.
+.It Fl r
+Edit or list
+.Pq Fl lr
+commands in reverse order.
+.It Fl s Op Ar old Ns = Ns Ar new
+Reexecute a single command
+without invoking an editor.
+The first occurrence of the string
.Ar old
-are replaced with
+in the command is replaced by
.Ar new .
-The meaning of
-.Cm -e -
-and
-.Fl s
-is identical: re-execute the selected command without invoking an editor.
-This command is usually accessed with the predefined
-.Ic alias r='fc -e -' .
-.Pp
-.It Ic fg Op Ar job ...
-Resume the specified job(s) in the foreground.
-If no jobs are specified,
-.Ic %+
-is assumed.
-See
-.Sx Job control
-below for more information.
+.El
.Pp
-.It Xo
-.Ic getopts
-.Ar optstring name
-.Op Ar arg ...
-.Xc
-Used by shell procedures to parse the specified arguments (or positional
-parameters, if no arguments are given) and to check for legal options.
-.Ar optstring
-contains the option letters that
-.Ic getopts
-is to recognize.
-If a letter is followed by a colon, the option is expected to
-have an argument.
-Options that do not take arguments may be grouped in a single argument.
-If an option takes an argument and the option character is not the
-last character of the argument it is found in, the remainder of the argument is
-taken to be the option's argument; otherwise, the next argument is the option's
-argument.
-.Pp
-Each time
+A range of commands can be specified,
+.Ar first
+to
+.Ar last .
+Their format can be numerical,
+to select by command number;
+.Sq - Ns Ar n ,
+to select a command executed that number of commands previous;
+or a string which matches the beginning of the command.
+If no range is given,
+the last command in command history is edited,
+or reexecuted
+.Pq Fl s ,
+or the previous 16 commands in command history are listed
+.Pq Fl l .
+If
+.Ar first
+is newer than
+.Ar last ,
+commands are processed in reverse order
+(as if
+.Fl r
+had been given);
+if either are out of range,
+the oldest or newest values are used.
+.It Ic fg Op Ar id ...
+Select a job by
+.Ar id
+(see the
+.Ic jobs
+command, below)
+to run in the foreground.
+The default job is
+.Qq %+ .
+.It Ic getopts Ar optstring name Op Ar arg ...
+When invoked,
.Ic getopts
-is invoked, it places the next option in the shell parameter
-.Ar name
-and the index of the argument to be processed by the next call to
+processes the positional parameters
+(or any
+.Ar arg
+passed to it)
+as a list of options and option arguments.
.Ic getopts
-in the shell parameter
-.Ev OPTIND .
-If the option was introduced with a
-.Ql + ,
-the option placed in
+sets the variable
.Ar name
-is prefixed with a
-.Ql + .
-When an option requires an argument,
-.Ic getopts
-places it in the shell parameter
-.Ev OPTARG .
+to the option found,
+.Ev OPTARG
+to its argument,
+and
+.Ev OPTIND
+to the index of the next variable to be processed.
.Pp
-When an illegal option or a missing option argument is encountered, a question
-mark or a colon is placed in
+The string
+.Ar optstring
+contains a list of acceptable options;
+a colon following an option indicates it may take an argument.
+If an option not recognised by
+.Ar optstring
+is found,
.Ar name
-(indicating an illegal option or missing argument, respectively) and
-.Ev OPTARG
-is set to the option character that caused the problem.
-Furthermore, if
+is set to
+.Sq ?\& ;
+if the first character of
.Ar optstring
-does not begin with a colon, a question mark is placed in
-.Ar name ,
+is a colon,
.Ev OPTARG
-is unset, and an error message is printed to standard error.
-.Pp
-When the end of the options is encountered,
-.Ic getopts
-exits with a non-zero exit status.
-Options end at the first (non-option
-argument) argument that does not start with a
-.Ql - ,
-or when a
-.Ql --
-argument is encountered.
-.Pp
-Option parsing can be reset by setting
-.Ev OPTIND
-to 1 (this is done automatically whenever the shell or a shell procedure is
-invoked).
-.Pp
-Warning: Changing the value of the shell parameter
-.Ev OPTIND
-to a value other than 1, or parsing different sets of arguments without
-resetting
-.Ev OPTIND ,
-may lead to unexpected results.
+is set to the unsupported option,
+otherwise an error message is displayed.
+.It Ic jobs Oo Fl l | p Oc Op Ar id ...
+Display the status of all jobs in the current shell environment,
+or those selected by
+.Ar id .
+.Pp
+The options to the
+.Ic jobs
+command are as follows:
.Pp
-.It Xo
-.Ic hash
-.Op Fl r
-.Op Ar name ...
-.Xc
-Without arguments, any hashed executable command pathnames are listed.
-The
-.Fl r
-option causes all hashed commands to be removed from the hash table.
-Each
-.Ar name
-is searched as if it were a command name and added to the hash table if it is
-an executable command.
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl l
+Additionally display the process group ID.
+.It Fl p
+Display only the process group ID.
+.El
.Pp
-.It Xo
-.Ic jobs
-.Op Fl lnp
-.Op Ar job ...
-.Xc
-Display information about the specified job(s); if no jobs are specified, all
-jobs are displayed.
-The
-.Fl n
-option causes information to be displayed only for jobs that have changed
-state since the last notification.
-If the
-.Fl l
-option is used, the process ID of each process in a job is also listed.
-The
-.Fl p
-option causes only the process group of each job to be printed.
-See
-.Sx Job control
-below for the format of
-.Ar job
-and the displayed job.
+Job
+.Ar id
+can be selected in one of the following ways:
.Pp
+.Bl -tag -width "%?string" -offset 3n -compact
+.It %%
+The current job.
+.It %+
+The current job.
+.It %-
+The previous job.
+.It % Ns Ar n
+Job number
+.Ar n .
+.It % Ns Ar string
+Job with command matching
+.Ar string .
+.It %? Ns Ar string
+Job with command containing
+.Ar string .
+.El
.It Xo
.Ic kill
-.Oo Fl s Ar signame \*(Ba
-.No - Ns Ar signum \*(Ba
-.No - Ns Ar signame Oc
-.No { Ar job \*(Ba pid \*(Ba pgrp No }
-.Ar ...
+.Op Fl l Op Ar signal
+.Op Fl s Ar signal
+.Oo Fl Ar signal Oc Ar pid ...
.Xc
-Send the specified signal to the specified jobs, process IDs, or process
-groups.
-If no signal is specified, the
-.Dv TERM
-signal is sent.
-If a job is specified, the signal is sent to the job's process group.
-See
-.Sx Job control
-below for the format of
-.Ar job .
+Send a signal,
+by default
+.Dv SIGTERM ,
+to the process with ID
+.Ar pid .
.Pp
-.It Xo
+The options to the
.Ic kill
-.Fl l
-.Op Ar exit-status ...
-.Xc
-Print the signal name corresponding to
-.Ar exit-status .
-If no arguments are specified, a list of all the signals, their numbers, and
-a short description of them are printed.
+command are as follows:
+.Pp
+.Bl -tag -width "-l [signal]" -offset 3n -compact
+.It Fl l Op Ar signal
+List all supported signals,
+or the signal name corresponding to
+.Ar signal
+number or the exit status of a command killed by a signal.
+.It Fl s Ar signal
+Send the process
+.Ar signal
+name.
+.It Fl Ar signal
+Send the process
+.Ar signal
+name or number.
+.It Ar pid
+A process ID,
+process group ID,
+or a job ID (see
+.Ic jobs ,
+above).
+The process ID 0 signals all processes in the current process group.
+.El
+.Pp
+The supported signal numbers are:
+.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It " 0"
+Do not signal a process,
+but determine whether an ID exists.
+.It " 1"
+.Dv SIGHUP :
+Terminal line hangup.
+.It " 2"
+.Dv SIGINT :
+Interrupt a program.
+.It " 3"
+.Dv SIGQUIT :
+Quit a program.
+.It " 6"
+.Dv SIGABRT :
+Call
+.Xr abort 3 .
+.It " 9"
+.Dv SIGKILL :
+Kill a program.
+Cannot be caught or ignored.
+.It "14"
+.Dv SIGALRM :
+Real-time timer expired.
+.It "15"
+.Dv SIGTERM :
+Software termination signal.
+.El
+.It Ic pwd Op Fl L | P
+Print the current working directory.
+.Pp
+The options to the
+.Ic pwd
+command are as follows:
+.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl L
+Print the logical path to the current working directory
+i.e. display symbolic links followed.
+.It Fl P
+Print the physical path to the current working directory
+i.e. display symbolic links resolved.
+.El
+.Pp
+If both options are given,
+the last specified is used;
+if none are given,
+the default is
+.Fl L .
+.It Ic read Oo Fl r Oc Ar name ...
+Read a line from standard input.
+The line is split into fields,
+with each field assigned to a variable,
+.Ar name ,
+in turn
+(first field assigned to first variable, and so on).
+If there are more fields than variables,
+the last variable will contain all the remaining fields.
+If there are more variables than fields,
+the remaining variables are set to empty strings.
+A backslash in the input line causes the shell to prompt for further input.
+.Pp
+The options to the
+.Ic read
+command are as follows:
+.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl r
+Ignore backslash sequences.
+.El
+.It Ic readonly Oo Fl p Oc Ar name Ns Op = Ns Ar value
+Mark variable
+.Ar name
+as readonly,
+and optionally set it to
+.Ar value .
+Readonly variables cannot be later assigned values or unset.
+.Pp
+The options to the
+.Ic readonly
+command are as follows:
.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl p
+Display the names and values of all readonly variables
+in a manner which can be reinput to the shell.
+.El
+.It Ic return Op Ar n
+Exit the current function or
+.Ic .\&
+script with exit status
+.Ar n ,
+or that of the last command executed.
.It Xo
-.Ic print
-.Oo
-.Fl nrsu Ns Oo Ar n Oc \*(Ba
-.Fl R Op Fl en
-.Oc
-.Op Ar argument ...
+.Ic set
+.Op Fl abCefhmnuvx
+.Op Fl o Op Ar option
+.Op Ar arg ...
.Xc
-.Ic print
-prints its arguments on the standard output, separated by spaces and
-terminated with a newline.
-The
-.Fl n
-option suppresses the newline.
-By default, certain C escapes are translated.
-These include
-.Ql \eb ,
-.Ql \ef ,
-.Ql \en ,
-.Ql \er ,
-.Ql \et ,
-.Ql \ev ,
-and
-.Ql \e0###
-.Po
-.Ql #
-is an octal digit, of which there may be 0 to 3
-.Pc .
-.Ql \ec
-is equivalent to using the
-.Fl n
-option.
-.Ql \e
-expansion may be inhibited with the
-.Fl r
-option.
-The
-.Fl s
-option prints to the history file instead of standard output; and the
-.Fl u
-option prints to file descriptor
+Set options and positional parameters.
+Without options or arguments,
+display the names and values of all shell variables.
+.Pp
+The options are described in the options description
+at the beginning of this manual.
+The sequence
+.Qq set -o
+displays the current option settings;
+the sequence
+.Qq set +o
+displays,
+in a format suitable to be reinput to the shell,
+a command suitable to achieve the current option settings.
+.Pp
+Any arguments are assigned to the positional parameters,
+with the special parameter
+.Sq #
+set to the number of positional parameters.
+The sequence
+.Qq set --
+indicates an end to option processing
+(i.e. only arguments follow);
+.Qq set --
+by itself unsets all positional parameters
+and sets
+.Sq #
+to zero.
+.It Ic shift Op Ar n
+Shift the positional parameters
.Ar n
-.Po
+times
+(by default once).
+Parameter 1 takes the value of parameter
+.Sq 1+ Ns Ar n ,
+parameter 2 takes
+.Sq 2+ Ns Ar n ,
+and so on.
+Parameters
+.Sq #
+to
+.Sq Po #\(mi Ns Ar n Pc Ns +1
+and downwards are unset and
+.Sq #
+is updated to the new number of positional parameters.
+If
.Ar n
-defaults to 1 if omitted
-.Pc .
+is 0,
+no change occurs.
+.It Ic times
+Display accumulated process times for the shell (user and system)
+and all child processes (user and system).
+.It Ic true
+Return a true (zero) value.
+.It Ic trap Op Ar action signal ...
+Perform
+.Ar action
+whenever
+.Ar signal
+is caught.
+Without arguments,
+display a list of all traps and actions,
+in a format suitable to be reinput to the shell.
.Pp
-The
-.Fl R
-option is used to emulate, to some degree, the
-.Bx
-.Xr echo 1
-command, which does not process
-.Ql \e
-sequences unless the
-.Fl e
-option is given.
-As above, the
-.Fl n
-option suppresses the trailing newline.
-.Pp
-.It Ic pwd Op Fl LP
-Print the present working directory.
-If the
-.Fl L
-option is used or if the
-.Ic physical
-option isn't set (see the
-.Ic set
-command below), the logical path is printed (i.e. the path used to
-.Ic cd
-to the current directory).
-If the
-.Fl P
-option (physical path) is used or if the
-.Ic physical
-option is set, the path determined from the filesystem (by following
-.Sq ..
-directories to the root directory) is printed.
+If
+.Ar action
+is
+.Sq -
+or an integer,
+reset
+.Ar signal
+to its default value;
+if it is empty
+.Pq Qq ,
+ignore
+.Ar signal .
+If
+.Ar signal
+is
+.Qq EXIT
+or 0,
+perform
+.Ar action
+when the shell exits;
+otherwise
+.Ar signal
+should be a signal name
+(without the SIG prefix)
+or number.
+.It Ic umask Oo Fl S Oc Op Ar mask
+Set the file mode creation mask to
+.Ar mask .
+The creation mask determines the default permissions
+a newly created file or directory will have.
+If
+.Ar mask
+is not specified,
+display the current creation mask.
.Pp
-.It Xo
-.Ic read
-.Op Fl rsu Ns Op Ar n
-.Op Ar parameter ...
-.Xc
-Reads a line of input from the standard input, separates the line into fields
-using the
-.Ev IFS
-parameter (see
-.Sx Substitution
-above), and assigns each field to the specified parameters.
-If there are more parameters than fields, the extra parameters are set to
-.Dv NULL ,
-or alternatively, if there are more fields than parameters, the last parameter
-is assigned the remaining fields (inclusive of any separating spaces).
-If no parameters are specified, the
-.Ev REPLY
-parameter is used.
-If the input line ends in a backslash and the
-.Fl r
-option was not used, the backslash and the newline are stripped and more input
-is read.
-If no input is read,
-.Ic read
-exits with a non-zero status.
+The options to the
+.Ic umask
+command are as follows:
.Pp
-The first parameter may have a question mark and a string appended to it, in
-which case the string is used as a prompt (printed to standard error before
-any input is read) if the input is a
-.Xr tty 4
-(e.g.\&
-.Ic read nfoo?'number of foos: ' ) .
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl S
+Display symbolic output.
+.El
.Pp
-The
-.Fl u Ns Ar n
-option causes input to be read from file descriptor
-.Ar n
-.Pf ( Ar n
-defaults to 0 if omitted).
-If the
-.Fl s
-option is used, input is saved to the history file.
+See
+.Xr chmod 1
+for the format of
+.Ar mask .
+.It Ic unalias Oo Fl a Oc Ar name ...
+Remove the alias definition of alias
+.Ar name .
.Pp
-.It Xo
-.Ic readonly
-.Op Fl p
-.Oo Ar parameter
-.Op Ns = Ns Ar value
-.Ar ... Oc
-.Xc
-Sets the read-only attribute of the named parameters.
-If values are given,
-parameters are set to them before setting the attribute.
-Once a parameter is
-made read-only, it cannot be unset and its value cannot be changed.
-.Pp
-If no parameters are specified, the names of all parameters with the read-only
-attribute are printed one per line, unless the
-.Fl p
-option is used, in which case
-.Ic readonly
-commands defining all read-only parameters, including their values, are
-printed.
+The options to the
+.Ic unalias
+command are as follows:
.Pp
-.It Ic return Op Ar status
-Returns from a function or
-.Ic .\&
-script, with exit status
-.Ar status .
-If no
-.Ar status
-is given, the exit status of the last executed command is used.
-If used outside of a function or
-.Ic .\&
-script, it has the same effect as
-.Ic exit .
-Note that
-.Nm pdksh
-treats both profile and
-.Ev ENV
-files as
-.Ic .\&
-scripts, while the original Korn shell only treats profiles as
-.Ic .\&
-scripts.
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl a
+Remove all alias definitions.
+.El
+.It Ic unset Oo Fl fv Oc Ar name ...
+Unset variable or function
+.Ar name .
.Pp
+The options to the
+.Ic unset
+command are as follows:
+.Pp
+.Bl -tag -width Ds -offset 3n -compact
+.It Fl f
+Treat
+.Ar name
+as a function.
+.It Fl v
+Treat
+.Ar name
+as a variable (the default).
+.El
+.It Ic wait Op Ar pid ...
+Wait until all the processes specified by process or job ID
+.Ar pid
+have terminated.
+If no
+.Ar pid
+is specified,
+wait until all processes have terminated.
+The exit status is 0 on success,
+1\(en126 if an error occurs,
+or 127 if
+.Ar pid
+was unknown.
+.El
+.Sh COMMAND HISTORY AND COMMAND LINE EDITING
+When a shell is interactive,
+it keeps a record of commands run in a
+.Em command history ,
+either internally in memory or in a file,
+as determined by
+.Dv HISTFILE .
+The command line and all the commands in command history
+can be edited using commands similar to those of
+.Xr vi 1 .
+.Pp
+There are two modes,
+.Em interactive
+and
+.Em command .
+The shell starts in interactive mode.
+In this mode text is entered normally.
+A
+.Aq newline
+executes the current command line.
+The command line, unless empty, is entered into command history.
+The
+.Aq ESC
+key is used to enter command mode,
+where commands similar to those used by
+.Xr vi 1
+are available.
+A Ctrl-L sequence
+.Pq ^L
+can be used in this mode to
+redraw the current command line.
+.Pp
+Where noted,
+some commands may be preceded by a numerical
+.Ar count ,
+which causes the command to be repeated that number of times.
+The term
+.Em word
+is used to denote a sequence of letters, digits, or underscores;
+.Em bigword
+denotes a sequence of whitespace delineated characters.
+.Pp
+The commands for command mode:
+.Bl -tag -width "<newline>"
+.It Ic =
+Display the possible shell word expansion.
+.It Ic \e
+Perform pathname expansion on the current word,
+matching the largest possible unique expansion,
+then enter insert mode.
+.It Ic *
+Perform pathname expansion on the current word,
+substituting every possible expansion,
+then enter insert mode.
+.It Ic @ Ns Ar c
+Perform the commands defined by the alias
+.No _ Ns Ar c ,
+where
+.Ar c
+is a single letter alphabetical character.
+.It Oo Ar count Oc Ns Ic ~
+Convert the character from lowercase to upper or vice versa.
+.It Oo Ar count Oc Ns Ic .\&
+Repeat the most recent non-motion command.
+If no
+.Ar count
+is given, use that of the repeated command,
+if any.
+.It Oo Ar n Oc Ns Ic v
+Use
+.Xr vi 1
+to edit command number
+.Ar n
+in command history,
+or the current command if none given.
.It Xo
-.Ic set Op Ic +-abCefhkmnpsuvXx
-.Op Ic +-o Ar option
-.Op Ic +-A Ar name
-.Op Fl -
-.Op Ar arg ...
+.Oo Ar count Oc Ns Ic l ,
+.Oo Ar count Oc Ns Aq space
.Xc
+Move right.
+.It Oo Ar count Oc Ns Ic h
+Move left.
+.It Oo Ar count Oc Ns Ic w
+Move to the start of the next word.
+.It Oo Ar count Oc Ns Ic W
+Move to the start of the next big word.
+.It Oo Ar count Oc Ns Ic e
+Move to the end of the current word,
+or the end of the next word if the cursor is currently
+at the end of a word.
+.It Oo Ar count Oc Ns Ic E
+Move to the end of the current bigword,
+or the end of the next bigword if the cursor is currently
+at the end of a bigword.
+.It Oo Ar count Oc Ns Ic b
+Move to the start of the current word,
+or the start of the next word if the cursor is currently
+at the start of a word.
+.It Oo Ar count Oc Ns Ic b
+Move to the start of the current bigword,
+or the start of the next bigword if the cursor is currently
+at the start of a bigword.
+.It Ic ^
+Move to the first non-blank character.
+.It Ic $
+Move to the end of the current line.
+.It Ic 0
+Move to the beginning of the current line.
+.It Oo Ar count Oc Ns Ic |\&
+Move to the beginning of the current line
+or the character position specified by
+.Ar count .
+.It Oo Ar count Oc Ns Ic f Ns Ar c
+Move to the next instance of the
+character
+.Ar c .
+.It Oo Ar count Oc Ns Ic F Ns Ar c
+Move to the last instance of the
+character
+.Ar c .
+.It Oo Ar count Oc Ns Ic t Ns Ar c
+Move to the character before the next instance of the
+character
+.Ar c .
+.It Oo Ar count Oc Ns Ic T Ns Ar c
+Move to the character after the last instance of the
+character
+.Ar c .
+.It Oo Ar count Oc Ns Ic ;\&
+Repeat the last
+.Ic f , F , t ,
+or
+.Ic T
+command.
+Ignore any
+.Ar count
+specified with the last command.
+.It Oo Ar count Oc Ns Ic ,\&
+Repeat the last
+.Ic f , F , t ,
+or
+.Ic T
+command,
+but in the opposite direction.
+Ignore any
+.Ar count
+specified with the last command.
+.It Ic a
+Enter insert mode after the current cursor position.
+.It Ic A
+Enter insert mode after the end of the current line.
+.It Ic i
+Enter insert mode at the current cursor position.
+.It Ic I
+Enter insert mode at the beginning of the current line.
+.It Ic R
+Enter insert mode at the current cursor position,
+replacing any characters thereafter.
+.It Oo Ar count Oc Ns Ic c Ns Ar motion
+Delete the characters between the cursor and the motion command specified,
+then enter insert mode.
+A special motion command,
+.Ic c ,
+may be used to delete the entire line.
The
-.Ic set
-command can be used to set
-.Pq Ic -
-or clear
-.Pq Ic +
-shell options, set the positional parameters, or set an array parameter.
-Options can be changed using the
-.Cm +-o Ar option
-syntax, where
-.Ar option
-is the long name of an option, or using the
-.Cm +- Ns Ar letter
-syntax, where
-.Ar letter
-is the option's single letter name (not all options have a single letter name).
-The following table lists both option letters (if they exist) and long names
-along with a description of what the option does:
-.Bl -tag -width 15n
-.It Fl A Ar name
-Sets the elements of the array parameter
-.Ar name
+.Ar count
+argument is ignored for the commands
+.Ic 0 , ^ , $ ,
+and
+.Ic c .
+If the motion moves towards the beginning of the line
+the character under the cursor is not deleted;
+if it moves towards the end of the line
+it is deleted.
+.It Ic C
+Delete the characters between the cursor and the line end,
+then enter insert mode.
+.It Ic S
+Clear the entire line,
+then enter insert mode.
+.It Oo Ar count Oc Ns Ic r
+Replace the character under the cursor with the next typed character.
+With a
+.Ar count ,
+replace the current character
+and the corresponding number of following characters.
+.It Oo Ar count Oc Ns Ic _
+After the cursor,
+append a
+.Aq space
+and the
+.Ar count Ns th
+bigword (by default the last entered)
+from the previous input line,
+then enter insert mode.
+.It Oo Ar count Oc Ns Ic x
+Delete the character under the cursor,
+placing it in the save buffer.
+.It Oo Ar count Oc Ns Ic X
+Delete the character before the cursor,
+placing it in the save buffer.
+.It Oo Ar count Oc Ns Ic d Ns Ar motion
+Delete the characters between the cursor and the motion command specified,
+placing them in the save buffer.
+A special motion command,
+.Ic d ,
+may be used to delete the entire line.
+If the motion moves towards the beginning of the line
+the character under the cursor is not deleted.
+.It Oo Ar count Oc Ns Ic D
+Delete the characters between the cursor and the line end,
+placing them in the save buffer.
+.It Oo Ar count Oc Ns Ic y Ns Ar motion
+Yank (copy) the characters between the cursor and the motion command specified,
+placing them in the save buffer.
+A special motion command,
+.Ic y ,
+may be used to yank the entire line.
+If the motion moves towards the beginning of the line
+the character under the cursor is not yanked.
+.It Oo Ar count Oc Ns Ic Y
+Yank (copy) the characters between the cursor and the line end,
+placing them in the save buffer.
+.It Oo Ar count Oc Ns Ic p
+Paste the contents of the save buffer after the cursor.
+.It Oo Ar count Oc Ns Ic P
+Paste the contents of the save buffer before the cursor.
+.It Oo Ar count Oc Ns Ic u
+Undo the last change to the edit line.
+.It Oo Ar count Oc Ns Ic U
+Undo all changes to the edit line.
+.It Xo
+.Oo Ar count Oc Ns Ic k ,
+.Oo Ar count Oc Ns Ic -\&
+.Xc
+Replace the current command line with the previous entry in history.
+.It Xo
+.Oo Ar count Oc Ns Ic j ,
+.Oo Ar count Oc Ns Ic +\&
+.Xc
+Replace the current command line with the next entry in history.
+.It Oo Ar n Oc Ns Ic G
+Replace the current command line with command number
+.Ar n
+in command history,
+or the oldest command if none given.
+.It / Ns Ar pattern
+Moving backwards through history,
+replace the current command line with the first that matches
+.Ar pattern .
+A
+.Sq ^
+at the beginning of the pattern searches only for entries beginning with
+.Ar pattern .
+An empty pattern matches the last search.
+.It ? Ns Ar pattern
+As above,
+but searching forwards.
+.It Ic n
+Repeat the most recent pattern search.
+.It Ic N
+Repeat the most recent pattern search,
+but in the opposite direction.
+.El
+.Sh SHELL GRAMMAR
+The shell reads its input as described above.
+After that it follows a fairly simple chain of operations
+to parse that input:
+.Bl -dash
+.It
+The shell breaks the input into
+.Em words
+and
+.Em operators .
+Words are the command text the user wishes run;
+operators are special characters which describe
+how the shell should interact with the commands.
+.It
+The shell
+.Em expands
+the command text according to the rules of expansion.
+.It
+Words are subject to
+.Em field splitting ,
+where the command text is separated into commands
+and arguments to commands.
+.It
+The shell performs any
+.Em redirection .
+.It
+The shell runs the commands.
+Argument names are assigned to
+.Em positional parameters ,
+with the command name itself assigned parameter 0.
+.It
+If the command is not being run in the background,
+the shell waits for it to complete
+and collects its exit status.
+.El
+.Ss Quoting
+Some characters have special meaning to the shell and need
+.Em quoting
+if the user wants to indicate to the shell not to interpret them as such.
+The following characters need quoting if their literal meaning is desired:
+.Bd -literal -offset indent
+| & ; < > ( ) $ \` \e " \(aq <space> <tab> <newline>
+* ? [ # ~ = %
+.Ed
+.Pp
+A backslash
+.Pq \e
+can be used to quote any character except a newline.
+If a newline follows a backslash the shell removes them both,
+effectively making the following line part of the current one.
+.Pp
+A group of characters can be enclosed within single quotes
+.Pq \(aq
+to quote every character within the quotes.
+.Pp
+A group of characters can be enclosed within double quotes
+.Pq \&"
+to quote every character within the quotes
+except a backquote
+.Pq \`
+or a dollar sign
+.Pq $ ,
+both of which retain their special meaning.
+A backslash
+.Pq \e
+within double quotes retains its special meaning,
+but only when followed by a backquote, dollar sign,
+double quote, or another backslash.
+An at sign
+.Pq @
+within double quotes has a special meaning
+(see
+.Sx SPECIAL PARAMETERS ,
+below).
+.Pp
+Similarly command words need to be quoted
+if they are not to be interpreted as such.
+.Ss Expansion
+Shell
+.Em variables
+are arbitrary names assigned values using the
+.Sq =
+operator;
+the values can be retrieved using the syntax
+.No $ Ns Ar variable .
+Shell
+.Em parameters
+are variable names,
+numbers,
+or any of the characters listed in
+.Sx SPECIAL PARAMETERS .
+.Pp
+The shell is able to
+.Em expand
+certain elements of its syntax,
+allowing for a more concise notation
+and providing a convenience to the user.
+.Pp
+Firstly, tilde expansion occurs on words beginning with the
+.Sq ~
+character.
+Any characters following the tilde,
+up to the next colon, slash, or blank,
+are taken as a login name
+and substituted with that user's home directory,
+as defined in
+.Xr passwd 5 .
+A tilde by itself is expanded to the contents of the variable
+.Ev HOME .
+This notation can be used in variable assignments,
+in the assignment half,
+immediately after the equals sign or a colon,
+up to the next slash or colon, if any.
+.Pp
+.Dl PATH=~alice:~bob/jobs
+.Pp
+Parameter expansion happens after tildes have been expanded,
+with the value of the parameter being substituted.
+The basic format is:
+.Pp
+.D1 $ Ns Brq Ar parameter
+.Pp
+The braces are optional
+except for positional parameters 10 and higher,
+or where the parameter name is followed by other characters
+that would prevent it from being expanded.
+If parameter expansion occurs within double quotes,
+neither pathname expansion nor field splitting happens afterwards.
+.Pp
+Some special forms of parameter expansion are available.
+In the formats below,
+.Ar word
+itself is subject to expansion,
+and, if omitted,
+the empty string is used.
+If the colon is omitted,
+.Ar word
+is substituted only if
+.Ar parameter
+is unset (not if it is empty).
+.Bl -tag -width Ds
+.It $ Ns Brq Ar parameter Ns :- Ns Op Ar word
+Substitute
+.Ar parameter .
+If
+.Ar parameter
+is unset or empty,
+substitute
+.Ar word .
+.It $ Ns Brq Ar parameter Ns := Ns Op Ar word
+Substitute
+.Ar parameter .
+If
+.Ar parameter
+is unset or empty,
+first assign the value of
+.Ar word
to
-.Ar arg ...
+.Ar parameter .
+.It $ Ns Brq Ar parameter Ns :? Ns Op Ar word
+Substitute
+.Ar parameter .
If
-.Fl A
-is used, the array is reset (i.e. emptied) first; if
-.Ic +A
-is used, the first N elements are set (where N is the number of arguments);
-the rest are left untouched.
-.It Fl a \*(Ba Ic allexport
-All new parameters are created with the export attribute.
-.It Fl b \*(Ba Ic notify
-Print job notification messages asynchronously, instead of just before the
-prompt.
-Only used if job control is enabled
-.Pq Fl m .
-.It Fl C \*(Ba Ic noclobber
-Prevent \*(Gt redirection from overwriting existing files.
-Instead, \*(Gt\*(Ba must be used to force an overwrite.
-.It Fl e \*(Ba Ic errexit
-Exit (after executing the
-.Dv ERR
-trap) as soon as an error occurs or a command fails (i.e. exits with a
-non-zero status).
-This does not apply to commands whose exit status is
-explicitly tested by a shell construct such as
-.Ic if ,
-.Ic until ,
-.Ic while ,
-or
-.Ic !\&
-statements.
-For
-.Ic &&
+.Ar parameter
+is unset or empty,
+the result of the expansion of
+.Ar word
+is written to standard error
+and the shell exits with a non-zero exit status.
+If
+.Ar word
+is omitted,
+the string
+.Qq parameter null or not set
+is used.
+.It $ Ns Brq Ar parameter Ns :+ Ns Op Ar word
+Substitute
+.Ar word .
+If
+.Ar parameter
+is unset or empty,
+substitute the empty string.
+.It $ Ns Brq # Ns Ar parameter
+The length, in characters, of
+.Ar parameter .
+.It $ Ns Brq Ar parameter Ns % Ns Op Ar word
+Substitute
+.Ar parameter ,
+deleting the smallest possible suffix matching
+.Ar word .
+.It $ Ns Brq Ar parameter Ns %% Ns Op Ar word
+Substitute
+.Ar parameter ,
+deleting the largest possible suffix matching
+.Ar word .
+.It $ Ns Brq Ar parameter Ns # Ns Op Ar word
+Substitute
+.Ar parameter ,
+deleting the smallest possible prefix matching
+.Ar word .
+.It $ Ns Brq Ar parameter Ns ## Ns Op Ar word
+Substitute
+.Ar parameter ,
+deleting the largest possible prefix matching
+.Ar word .
+.El
+.Pp
+Command expansion has a command executed in a subshell
+and the results output in its place.
+The basic format is:
+.Pp
+.D1 $ Ns Pq Ar command
or
-.Ic || ,
-only the status of the last command is tested.
-.It Fl f \*(Ba Ic noglob
-Do not expand file name patterns.
-.It Fl h \*(Ba Ic trackall
-Create tracked aliases for all executed commands (see
-.Sx Aliases
-above).
-Enabled by default for non-interactive shells.
-.It Fl k \*(Ba Ic keyword
-Parameter assignments are recognized anywhere in a command.
-.It Fl m \*(Ba Ic monitor
-Enable job control (default for interactive shells).
-.It Fl n \*(Ba Ic noexec
-Do not execute any commands.
-Useful for checking the syntax of scripts
-(ignored if interactive).
-.It Fl p \*(Ba Ic privileged
-The shell is a privileged shell.
-It is set automatically if, when the shell starts,
-the real UID or GID does not match
-the effective UID (EUID) or GID (EGID), respectively.
-See above for a description of what this means.
-.It Fl s \*(Ba Ic stdin
-If used when the shell is invoked, commands are read from standard input.
-Set automatically if the shell is invoked with no arguments.
-.Pp
-When
-.Fl s
-is used with the
-.Ic set
-command it causes the specified arguments to be sorted before assigning them to
-the positional parameters (or to array
-.Ar name ,
+.D1 \` Ns Ar command Ns \`
+.Pp
+The results are subject to field splitting and pathname expansion;
+no other form of expansion happens.
+If
+.Ar command
+is contained within double quotes,
+field splitting does not happen either.
+Within backquotes,
+a backslash is treated literally unless it follows
+a dollar sign, backquote, or another backslash.
+Commands can be nested,
+though the backquoted version requires backslashes before the backquotes.
+If
+.Ar command
+is run in a subshell in the bracketed version,
+the syntax is identical to that of arithmetic expansion.
+In that case the shell attempts arithmetic expansion first,
+then attempts command substitution if that fails.
+Or a non-ambiguous version can be used:
+.Pp
+.D1 $( Pf ( Ar command Ns Pf ) \ \&)
+.Pp
+Arithmetic expansion works similarly,
+with an arithmetic expression being evaluated and substituted.
+The format is:
+.Pp
+.D1 $ Ns Pq Pq Ar expression
+.Pp
+Where
+.Ar expression
+is an integer, parameter name, or array reference,
+optionally combined with any of the operators described below,
+listed and grouped according to precedence:
+.Bl -tag -width Ds
+.It ()\&
+Operators within brackets have highest precedence.
+Compare 3+2*4, which is 11,
+since multiplication has higher precedence than addition,
+and (3+2)*4, which is 20.
+.It + - ~ !\&
+Unary plus
+(indicates a positive value; integers are positive by default),
+unary minus (indicates a negative value),
+bitwise NOT,
+and logical NOT
+(the result is 1 if the argument is zero, or 0 otherwise), respectively.
+.It * / %
+Multiplication, division, and modulus (remainder), respectively.
+.It + -
+Addition and subtraction, respectively.
+.It << >>
+Shift left or right, respectively.
+.It < <= > >=
+Less than, less than or equal to,
+greater than, and greater than or equal to, respectively.
+The result is 1 if true, or 0 otherwise.
+.It == !=
+Equal (the result is 1 if both arguments are equal, and 0 otherwise)
+and not equal (the result is 1 if both arguments are non-zero, and 0 otherwise),
+respectively.
+.It &
+Bitwise AND.
+.It ^
+Bitwise exclusive OR.
+.It |
+Bitwise inclusive OR.
+.It &&
+Logical AND.
+The result is 1 if both arguments are non-zero, or 0 otherwise.
+.It ||
+Logical OR.
+The result is 1 if either argument is non-zero, or 0 otherwise.
+.It Ar expression ? Ns Ar expr1 : Ns Ar expr2
+The result is
+.Ar expr1
if
-.Fl A
-is used).
-.It Fl u \*(Ba Ic nounset
-Referencing of an unset parameter is treated as an error, unless one of the
-.Ql - ,
-.Ql + ,
+.Ar expression
+is non-zero,
or
-.Ql =
-modifiers is used.
-.It Fl v \*(Ba Ic verbose
-Write shell input to standard error as it is read.
-.It Fl X \*(Ba Ic markdirs
-Mark directories with a trailing
-.Ql /
-during file name generation.
-.It Fl x \*(Ba Ic xtrace
-Print commands and parameter assignments when they are executed, preceded by
-the value of
-.Ev PS4 .
-.It Ic bgnice
-Background jobs are run with lower priority.
-.It Ic ignoreeof
-The shell will not exit when end-of-file is read;
-.Ic exit
-must be used.
-.It Ic interactive
-The shell is an interactive shell.
-This option can only be used when the shell is invoked.
-See above for a description of what this means.
-.It Ic login
-The shell is a login shell.
-This option can only be used when the shell is invoked.
-See above for a description of what this means.
-.It Ic nohup
-Do not kill running jobs with a
-.Dv SIGHUP
-signal when a login shell exits.
-Currently set by default, but this will
-change in the future to be compatible with the original Korn shell (which
-doesn't have this option, but does send the
-.Dv SIGHUP
-signal).
-.It Ic nolog
-No effect.
-In the original Korn shell, this prevents function definitions from
-being stored in the history file.
-.It Ic physical
-Causes the
-.Ic cd
-and
-.Ic pwd
-commands to use
-.Dq physical
-(i.e. the filesystem's)
-.Sq ..
-directories instead of
-.Dq logical
-directories (i.e. the shell handles
-.Sq .. ,
-which allows the user to be oblivious of symbolic links to directories).
-Clear by default.
-Note that setting this option does not affect the current value of the
-.Ev PWD
-parameter; only the
-.Ic cd
-command changes
-.Ev PWD .
-See the
-.Ic cd
-and
-.Ic pwd
-commands above for more details.
-.It Ic posix
-Enable POSIX mode.
-See
-.Sx POSIX mode
-above.
-.It Ic restricted
-The shell is a restricted shell.
-This option can only be used when the shell is invoked.
-See above for a description of what this means.
-.It Ic vi
-Enable
-.Xr vi 1 Ns -like
-command-line editing (interactive shells only).
-.It Ic vi-esccomplete
-In vi command-line editing, do command and file name completion when escape
-(^[) is entered in command mode.
-.It Ic vi-show8
-Prefix characters with the eighth bit set with
-.Sq M- .
-If this option is not set, characters in the range 128\-160 are printed as is,
-which may cause problems.
-.It Ic vi-tabcomplete
-In vi command-line editing, do command and file name completion when tab (^I)
-is entered in insert mode.
-.It Ic viraw
-No effect.
-In the original Korn shell, unless
-.Ic viraw
-was set, the vi command-line mode would let the
-.Xr tty 4
-driver do the work until ESC (^[) was entered.
-.Nm pdksh
-is always in viraw mode.
+.Ar expr2
+otherwise.
+.It = *= /= %= += -= <<= >>= &= ^= |=
+Assignment.
+The notation
+.Ar var Ns *= Ns Ar expression
+is equivalent to
+.Ar var Ns = Ns Ar var Ns * Ns Ar expression .
.El
.Pp
-These options can also be used upon invocation of the shell.
-The current set of
-options (with single letter names) can be found in the parameter
-.Sq $- .
-.Ic set Fl o
-with no option name will list all the options and whether each is on or off;
-.Ic set +o
-will print the long names of all options that are currently on.
-.Pp
-Remaining arguments, if any, are positional parameters and are assigned, in
-order, to the positional parameters (i.e. $1, $2, etc.).
-If options end with
-.Ql --
-and there are no remaining arguments, all positional parameters are cleared.
-If no options or arguments are given, the values of all names are printed.
-For unknown historical reasons, a lone
-.Ql -
-option is treated specially \- it clears both the
-.Fl x
-and
-.Fl v
-options.
-.Pp
-.It Ic shift Op Ar number
-The positional parameters
-.Ar number Ns +1 ,
-.Ar number Ns +2 ,
-etc. are renamed to
-.Sq 1 ,
-.Sq 2 ,
-etc.
-.Ar number
-defaults to 1.
-.Pp
-.It Ic test Ar expression
-.It Ic \&[ Ar expression Ic \&]
-.Ic test
-evaluates the
-.Ar expression
-and returns zero status if true, 1 if false, or greater than 1 if there
-was an error.
-It is normally used as the condition command of
-.Ic if
+After the various types of expansion listed above have been carried out,
+the shell subjects everything that did not occur in double quotes to
+.Em field splitting ,
+where words are broken up according to the value of the
+.Ev IFS
+variable.
+Each character of
+.Ev IFS
+is used to split fields;
+any
+.Ev IFS
+characters at the beginning and end of input are ignored.
+If
+.Ev IFS
+is unset, the default value consisting of
+.Aq space ,
+.Aq tab
and
-.Ic while
-statements.
-Symbolic links are followed for all
-.Ar file
-expressions except
-.Fl h
+.Aq newline
+is used; if the value of
+.Ev IFS
+is empty, no field splitting is performed.
+.Pp
+After field splitting,
+the shell matches filename patterns.
+.Bl -tag -width Ds
+.It ?
+A question mark matches any single character.
+.It *
+An asterisk matches multiple characters.
+.It [..]
+Matches any character enclosed in the brackets.
+The sense is negated if the first character is
+.Sq !\& .
+A closing bracket can be included in the list of characters to match
+by listing it as the first character after the opening bracket
+or by quoting it.
+Similarly a
+.Sq -
+should be specified last or quoted so that the shell does not think
+it is a character range (see below).
+.It [[: Ns Ar class Ns :]]
+Matches any character in the following character classes:
+.Bd -literal -offset indent
+alnum alpha blank cntrl
+digit graph lower print
+punct space upper xdigit
+.Ed
+.It Bq Ar x Ns - Ns Ar y
+Matches any character in the range between
+.Ar x
and
-.Fl L .
+.Ar y ,
+inclusive.
+.El
.Pp
-The following basic expressions are available:
-.Bl -tag -width 17n
-.It Fl a Ar file
-.Ar file
-exists.
-.It Fl b Ar file
-.Ar file
-is a block special device.
-.It Fl c Ar file
-.Ar file
-is a character special device.
-.It Fl d Ar file
-.Ar file
-is a directory.
-.It Fl e Ar file
+Slashes and full stops do not match the patterns above
+because of their use as path and filename characters.
+.Ss Redirection
+Redirection is used to open, close, or otherwise manipulate files,
+using redirection operators in combination with numerical
+.Em file descriptors .
+A minimum of ten (0\-9) descriptors are supported;
+by convention
+standard input is file descriptor 0,
+standard output file descriptor 1,
+and standard error file descriptor 2.
+In the examples given below,
+.Ar n
+represents a numerical file descriptor.
+The target for redirection is
.Ar file
-exists.
-.It Fl f Ar file
+and it is subject to all forms of expansion as listed above,
+except pathname expansion.
+If any part of the file descriptor or redirection operator is quoted,
+they are not recognised.
+.Bl -tag -width Ds
+.It Oo Ar n Oc Ns < Ns Ar file
+Open
.Ar file
-is a regular file.
-.It Fl G Ar file
-.Ar file Ns 's
-group is the shell's effective group ID.
-.It Fl g Ar file
-.Ar file Ns 's
-mode has the setgid bit set.
-.It Fl h Ar file
+for reading on file descriptor
+.Ar n ,
+by default standard input.
+.It Oo Ar n Oc Ns > Ns Ar file
+Write to
.Ar file
-is a symbolic link.
-.It Fl k Ar file
-.Ar file Ns 's
-mode has the
-.Xr sticky 8
-bit set.
-.It Fl L Ar file
+with file descriptor
+.Ar n ,
+by default standard output.
+If
.Ar file
-is a symbolic link.
-.It Fl O Ar file
-.Ar file Ns 's
-owner is the shell's effective user ID.
-.It Fl o Ar option
-Shell
-.Ar option
-is set (see the
-.Ic set
-command above for a list of options).
-As a non-standard extension, if the option starts with a
-.Ql \&! ,
-the test is negated; the test always fails if
-.Ar option
-doesn't exist (so [ -o foo -o -o !foo ] returns true if and only if option
-.Ar foo
-exists).
-.It Fl p Ar file
+does not exist,
+create it;
+if it does exist,
+truncate it to be empty before beginning to write to it.
+.It Oo Ar n Oc Ns >| Ns Ar file
+As above, but forces clobbering
+(see the
+.Fl C
+option).
+.It Oo Ar n Oc Ns >> Ns Ar file
+Append to
.Ar file
-is a named pipe.
-.It Fl r Ar file
+with file descriptor
+.Ar n ,
+by default standard output.
+If
.Ar file
-exists and is readable.
-.It Fl S Ar file
+does not exist,
+create it.
+.It Oo Ar n Oc Ns <<
+This form of redirection,
+called a
+.Em here document ,
+is used to copy a block of lines
+to a temporary file until a line matching
+.Ar delimiter
+is read.
+When the command is executed, standard input is redirected from the
+temporary file to file descriptor
+.Ar n ,
+or standard input by default.
+The basic format is:
+.Bd -unfilled -offset indent
+.Oo Ar n Oc Ns << Ns Ar delimiter
+text
+text
+\&...
+.Ar delimiter
+.Ed
+.Pp
+Provided
+.Ar delimiter
+doesn't contain any quoted characters,
+parameter, command, and arithmetic expansions are performed on
+the text block,
+and backslashes escape the special meaning of
+.Sq $ ,
+.Sq \` ,
+and
+.Sq \e .
+If multiple here documents are used on the same command line,
+they are saved and processed in order.
+.It Oo Ar n Oc Ns <<-
+Same as
+.Ic << ,
+except leading tabs are stripped from lines in
+.Ar block .
+.It Oo Ar n Oc Ns <& Ns Ar file
+Make file descriptor
+.Ar n ,
+by default standard input,
+a copy of the file descriptor denoted by
+.Ar file .
+If
.Ar file
-is a
-.Xr unix 4 Ns -domain
-socket.
-.It Fl s Ar file
+is
+.Sq - ,
+close file descriptor
+.Ar n
+or standard input.
+.It Oo Ar n Oc Ns >& Ns Ar file
+Make file descriptor
+.Ar n ,
+by default standard output,
+a copy of the file descriptor denoted by
+.Ar file .
+If
.Ar file
-is not empty.
-.It Fl t Op Ar fd
-File descriptor
-.Ar fd
-is a
-.Xr tty 4
-device.
-If the
-.Ic posix
-option is not set,
-.Ar fd
-may be left out, in which case it is taken to be 1 (the behaviour differs due
-to the special POSIX rules described above).
-.It Fl u Ar file
-.Ar file Ns 's
-mode has the setuid bit set.
-.It Fl w Ar file
+is
+.Sq - ,
+close file descriptor
+.Ar n
+or standard output.
+.It Oo Ar n Oc Ns <> Ns Ar file
+Open
.Ar file
-exists and is writable.
-.It Fl x Ar file
+for reading and writing on file descriptor
+.Ar n ,
+by default standard input.
+If
.Ar file
-exists and is executable.
-.It Ar file1 Fl nt Ar file2
-.Ar file1
-is newer than
-.Ar file2 .
-.It Ar file1 Fl ot Ar file2
-.Ar file1
-is older than
-.Ar file2 .
-.It Ar file1 Fl ef Ar file2
-.Ar file1
-is the same file as
-.Ar file2 .
-.It Ar string
-.Ar string
-has non-zero length.
-.It Fl n Ar string
-.Ar string
-is not empty.
-.It Fl z Ar string
-.Ar string
-is empty.
-.It Ar string No = Ar string
-Strings are equal.
-.It Ar string No != Ar string
-Strings are not equal.
-.It Ar number Fl eq Ar number
-Numbers compare equal.
-.It Ar number Fl ne Ar number
-Numbers compare not equal.
-.It Ar number Fl ge Ar number
-Numbers compare greater than or equal.
-.It Ar number Fl gt Ar number
-Numbers compare greater than.
-.It Ar number Fl le Ar number
-Numbers compare less than or equal.
-.It Ar number Fl \< Ar number
-Numbers compare less than.
+does not exist,
+create it.
.El
-.Pp
-The above basic expressions, in which unary operators have precedence over
-binary operators, may be combined with the following operators (listed in
-increasing order of precedence):
-.Bd -literal -offset indent
-expr -o expr Logical OR.
-expr -a expr Logical AND.
-! expr Logical NOT.
-( expr ) Grouping.
-.Ed
-.Pp
-On operating systems not supporting
-.Pa /dev/fd/ Ns Ar n
-devices (where
-.Ar n
-is a file descriptor number), the
-.Ic test
-command will attempt to fake it for all tests that operate on files (except the
-.Fl e
-test).
-For example,
-[ -w /dev/fd/2 ] tests if file descriptor 2 is writable.
-.Pp
-Note that some special rules are applied (courtesy of POSIX)
-if the number of
-arguments to
-.Ic test
-or
-.Ic \&[ ... \&]
-is less than five: if leading
-.Ql \&!
-arguments can be stripped such that only one argument remains then a string
-length test is performed (again, even if the argument is a unary operator); if
-leading
-.Ql \&!
-arguments can be stripped such that three arguments remain and the second
-argument is a binary operator, then the binary operation is performed (even
-if the first argument is a unary operator, including an unstripped
-.Ql \&! ) .
-.Pp
-.Sy Note :
-A common mistake is to use
-.Dq if \&[ $foo = bar \&] ,
-which fails if parameter
-.Dq foo
-is
-.Dv NULL
-or unset, if it has embedded spaces (i.e.\&
-.Ev IFS
-characters), or if it is a unary operator like
-.Sq \&!
+.Sh COMMANDS
+The shell first expands
+any words that are not variable assignments or redirections,
+with the first field being the command name
+and any successive fields arguments to that command.
+It sets up redirections, if any,
+and then expands variable assignments, if any.
+It then attempts to run the command.
+.Pp
+Firstly, it determines whether the command name contains any slashes.
+If it does not, and the shell implements the command as a special built-in,
+it then invokes the built-in.
+If not, but it is a non POSIX standard command,
+implemented as a shell function,
+it then invokes that.
+If not, but it is one of the commands
+.Ic alias , bg , cd , command ,
+.Ic false , fc , fg , getopts ,
+.Ic jobs , kill , newgrp , pwd ,
+.Ic read , true , umask , unalias ,
or
-.Sq Fl n .
-Use tests like
-.Dq if \&[ \&"X$foo\&" = Xbar \&]
-instead.
-.Pp
-.It Ic times
-Print the accumulated user and system times used both by the shell
-and by processes that the shell started which have exited.
-The format of the output is:
-.Bd -literal -offset indent
-0m0.00s 0m0.00s
-0m0.00s 0m0.00s
-.Ed
+.Ic wait ,
+it then invokes that.
.Pp
-.It Ic trap Op Ar handler signal ...
-Sets a trap handler that is to be executed when any of the specified signals are
-received.
-.Ar handler
-is either a
-.Dv NULL
-string, indicating the signals are to be ignored, a minus sign
-.Pq Sq - ,
-indicating that the default action is to be taken for the signals (see
-.Xr signal 3 ) ,
-or a string containing shell commands to be evaluated and executed at the first
-opportunity (i.e. when the current command completes, or before printing the
-next
-.Ev PS1
-prompt) after receipt of one of the signals.
-.Ar signal
-is the name of a signal (e.g.\&
-.Dv PIPE
-or
-.Dv ALRM )
-or the number of the signal (see the
-.Ic kill -l
-command above).
-.Pp
-There are two special signals:
-.Dv EXIT
-(also known as 0), which is executed when the shell is about to exit, and
-.Dv ERR ,
-which is executed after an error occurs (an error is something that would cause
-the shell to exit if the
-.Fl e
-or
-.Ic errexit
-option were set \- see the
-.Ic set
-command above).
-.Dv EXIT
-handlers are executed in the environment of the last executed command.
-Note
-that for non-interactive shells, the trap handler cannot be changed for signals
-that were ignored when the shell started.
-.Pp
-With no arguments,
-.Ic trap
-lists, as a series of
-.Ic trap
-commands, the current state of the traps that have been set since the shell
-started.
-Note that the output of
-.Ic trap
-cannot be usefully piped to another process (an artifact of the fact that
-traps are cleared when subprocesses are created).
-.Pp
-The original Korn shell's
-.Dv DEBUG
-trap and the handling of
-.Dv ERR
+Failing that, the value of
+.Ev PATH
+is used to search for the command.
+If it finds a match,
+and it is a POSIX standard command,
+implemented as a built-in or function,
+it then invokes it.
+Otherwise
+it attempts to execute the command in an environment separate from the shell.
+If it is unable to execute the command,
+it tries to run it as a shell script.
+.Pp
+Finally, if the command name does contain a slash,
+and it finds a match in
+.Ev PATH ,
+it attempts to execute the command in an environment separate from the shell.
+If it is unable to execute the command,
+it tries to run it as a shell script.
+.Pp
+A series of one or more commands separated by
+.Sq ;\&
+constitute a
+.Em sequential list ,
+where commands are executed in the order given.
+The exit status of a sequential list is that of the last command executed.
+The format for a sequential list is:
+.Pp
+.D1 Ar command\ \& ; Op Ar command ...
+.Pp
+A series of one or more commands separated by
+.Sq &
+constitute an
+.Em asynchronous list ,
+where the shell executes the command in a subshell
+and runs the next command without waiting for the previous one to finish.
+The exit status of an asynchronous list is always zero.
+The format for an asynchronous list is:
+.Pp
+.D1 Ar command No & Op Ar command ...
+.Pp
+A series of commands separated by
+.Sq |
+constitute a
+.Em pipeline ,
+where the output of one command
+is used as input for the next command.
+The exit status of a pipeline is that of the last command;
+if a pipeline begins
+.Sq !\&
+the exit status is inverted.
+The format for a pipeline is:
+.Pp
+.D1 Oo !\& Oc Ar command | command Op | Ar ...
+.Pp
+A series of commands separated by
+.Sq &&
+constitute an
+.Em AND list ,
+where a command is only executed if the exit status of the previous command was
+zero.
+The exit status of an AND list is that of the last command.
+The format for an AND list is:
+.Pp
+.D1 Ar command No && Ar command Op && Ar ...
+.Pp
+A series of commands separated by
+.Sq ||
+constitute an
+.Em OR list ,
+where a command is only executed if the exit status of the previous command was
+non-zero.
+The exit status of an OR list is that of the last command.
+The format for an OR list is:
+.Pp
+.D1 Ar command No || Ar command Op || Ar ...
+.Pp
+A series of commands separated by
+.Sq &&
+and
+.Sq ||
+constitute an
+.Em AND-OR list ,
+where
+.Sq &&
and
-.Dv EXIT
-traps in functions are not yet implemented.
+.Sq ||
+have equal precedence and are evaluated in the order they are given.
+The AND-OR list can be terminated with
+.Sq ;\&
+or
+.Sq &
+to have them execute sequentially or asynchronously, respectively.
+.Pp
+Command lists,
+as described above,
+can be enclosed within
+.Sq ()
+to have them executed in a subshell,
+or within
+.Sq {}
+to have them executed in the current environment:
+.Pp
+.D1 Pq Ar command ...
+.D1 Brq Ar \ \&command ... Ns ;\&
+.Pp
+Any redirections specified after the closing bracket apply to all commands
+within the brackets.
+An operator such as
+.Sq ;\&
+or a newline are needed to terminate a command list within curly braces.
+.Pp
+The shell has grammatical constructs
+which allow it to work its way (loop) through lists
+or evaluate things conditionally.
.Pp
-.It Ic true
-A command that exits with a zero value.
+A
+.Em for loop
+executes a series of commands for each item in a list.
+Its format is:
+.Bd -unfilled -offset indent
+.No for Ar name Op in Ar word ...
+do
+.No " " Ar command
+.No " " Ar ...
+done
+.Ed
.Pp
-.It Xo
-.Ic typeset
-.Oo
-.Op Ic +-lprtUux
-.Op Fl L Ns Op Ar n
-.Op Fl R Ns Op Ar n
-.Op Fl Z Ns Op Ar n
-.Op Fl i Ns Op Ar n
-.No \*(Ba Fl f Op Fl tux
-.Oc
-.Oo
+Firstly
+.Ar word ...
+is expanded to generate a list of items.
+The variable
.Ar name
-.Op Ns = Ns Ar value
-.Ar ...
-.Oc
-.Xc
-Display or set parameter attributes.
-With no
-.Ar name
-arguments, parameter attributes are displayed; if no options are used, the
-current attributes of all parameters are printed as
-.Ic typeset
-commands; if an option is given (or
-.Ql -
-with no option letter), all parameters and their values with the specified
-attributes are printed; if options are introduced with
-.Ql + ,
-parameter values are not printed.
+is set to each item, in turn,
+and the commands are executed for each item.
+The construct
+.Qq in word ...
+can be omitted,
+which is equivalent to: in \&"$@\&".
+The exit status is zero if there are no items
+or otherwise the exit status of the last command executed.
.Pp
-If
-.Ar name
-arguments are given, the attributes of the named parameters are set
-.Pq Ic -
-or cleared
-.Pq Ic + .
-Values for parameters may optionally be specified.
-If
-.Ic typeset
-is used inside a function, any newly created parameters are local to the
-function.
-.Pp
-When
-.Fl f
-is used,
-.Ic typeset
-operates on the attributes of functions.
-As with parameters, if no
-.Ar name
-arguments are given,
-functions are listed with their values (i.e. definitions) unless
-options are introduced with
-.Ql + ,
-in which case only the function names are reported.
-.Bl -tag -width Ds
-.It Fl f
-Function mode.
-Display or set functions and their attributes, instead of parameters.
-.It Fl i Ns Op Ar n
-Integer attribute.
-.Ar n
-specifies the base to use when displaying the integer (if not specified, the
-base given in the first assignment is used).
-Parameters with this attribute may
-be assigned values containing arithmetic expressions.
-.It Fl L Ns Op Ar n
-Left justify attribute.
-.Ar n
-specifies the field width.
-If
-.Ar n
-is not specified, the current width of a parameter (or the width of its first
-assigned value) is used.
-Leading whitespace (and zeros, if used with the
-.Fl Z
-option) is stripped.
-If necessary, values are either truncated or space padded
-to fit the field width.
-.It Fl l
-Lower case attribute.
-All upper case characters in values are converted to lower case.
-(In the original Korn shell, this parameter meant
-.Dq long integer
-when used with the
-.Fl i
-option.)
-.It Fl p
-Print complete
-.Ic typeset
-commands that can be used to re-create the attributes (but not the values) of
-parameters.
-This is the default action (option exists for ksh93 compatibility).
-.It Fl R Ns Op Ar n
-Right justify attribute.
-.Ar n
-specifies the field width.
-If
-.Ar n
-is not specified, the current width of a parameter (or the width of its first
-assigned value) is used.
-Trailing whitespace is stripped.
-If necessary, values are either stripped of leading characters or space
-padded to make them fit the field width.
-.It Fl r
-Read-only attribute.
-Parameters with this attribute may not be assigned to or unset.
-Once this attribute is set, it cannot be turned off.
-.It Fl t
-Tag attribute.
-Has no meaning to the shell; provided for application use.
-.Pp
-For functions,
-.Fl t
-is the trace attribute.
-When functions with the trace attribute are executed, the
-.Ic xtrace
-.Pq Fl x
-shell option is temporarily turned on.
-.It Fl U
-Unsigned integer attribute.
-Integers are printed as unsigned values (only
-useful when combined with the
-.Fl i
-option).
-This option is not in the original Korn shell.
-.It Fl u
-Upper case attribute.
-All lower case characters in values are converted to upper case.
-(In the original Korn shell, this parameter meant
-.Dq unsigned integer
-when used with the
-.Fl i
-option, which meant upper case letters would never be used for bases greater
-than 10.
-See the
-.Fl U
-option.)
-.Pp
-For functions,
-.Fl u
-is the undefined attribute.
-See
-.Sx Functions
-above for the implications of this.
-.It Fl x
-Export attribute.
-Parameters (or functions) are placed in the environment of
-any executed commands.
-Exported functions are not yet implemented.
-.It Fl Z Ns Op Ar n
-Zero fill attribute.
-If not combined with
-.Fl L ,
-this is the same as
-.Fl R ,
-except zero padding is used instead of space padding.
-.El
+A
+.Em while loop
+continuously executes a set of commands
+as long as the command or command list being tested in
+.Ar condition
+has a zero exit status.
+Its format is:
+.Bd -unfilled -offset indent
+.No while Ar condition
+do
+.No " " Ar command
+.No " " Ar ...
+done
+.Ed
.Pp
-.It Xo
-.Ic ulimit
-.Op Fl acdfHlmnpSst Op Ar value
-.Ar ...
-.Xc
-Display or set process limits.
-If no options are used, the file size limit
-.Pq Fl f
-is assumed.
-.Ar value ,
-if specified, may be either an arithmetic expression starting with a
-number or the word
-.Dq unlimited .
-The limits affect the shell and any processes created by the shell after a
-limit is imposed; limits may not be increased once they are set.
-.Bl -tag -width 5n
-.It Fl a
-Display all limits; unless
-.Fl H
-is used, soft limits are displayed.
-.It Fl c Ar n
-Impose a size limit of
-.Ar n
-blocks on the size of core dumps.
-.It Fl d Ar n
-Impose a size limit of
-.Ar n
-kilobytes on the size of the data area.
-.It Fl f Ar n
-Impose a size limit of
-.Ar n
-blocks on files written by the shell and its child processes (files of any
-size may be read).
-.It Fl H
-Set the hard limit only (the default is to set both hard and soft limits).
-.It Fl l Ar n
-Impose a limit of
-.Ar n
-kilobytes on the amount of locked (wired) physical memory.
-.It Fl m Ar n
-Impose a limit of
-.Ar n
-kilobytes on the amount of physical memory used.
-.It Fl n Ar n
-Impose a limit of
-.Ar n
-file descriptors that can be open at once.
-.It Fl p Ar n
-Impose a limit of
-.Ar n
-processes that can be run by the user at any one time.
-.It Fl S
-Set the soft limit only (the default is to set both hard and soft limits).
-.It Fl s Ar n
-Impose a size limit of
-.Ar n
-kilobytes on the size of the stack area.
-.It Fl t Ar n
-Impose a time limit of
-.Ar n
-CPU seconds spent in user mode to be used by each process.
-.\".It Fl v Ar n
-.\"Impose a limit of
-.\".Ar n
-.\"kilobytes on the amount of virtual memory used.
-.El
+Multiple commands may be given by grouping them in lists,
+as described above,
+or by separating them with newlines.
+The exit status is zero if the commands after
+.Qq do
+were never executed
+or otherwise the exit status of the last command executed.
+.Pp
+An
+.Em until loop
+continuously executes a set of commands
+as long as the command or command list being tested in
+.Ar condition
+has a non-zero exit status.
+Its format is:
+.Bd -unfilled -offset indent
+.No until Ar condition
+do
+.No " " Ar command
+.No " " Ar ...
+done
+.Ed
.Pp
-As far as
-.Ic ulimit
-is concerned, a block is 512 bytes.
+Multiple commands may be given by grouping them in lists,
+as described above,
+or by separating them with newlines.
+The exit status is zero if the commands after
+.Qq do
+were never executed
+or otherwise the exit status is that of the last command executed.
.Pp
-.It Xo
-.Ic umask
-.Op Fl S
-.Op Ar mask
-.Xc
-Display or set the file permission creation mask, or umask (see
-.Xr umask 2 ) .
-If the
-.Fl S
-option is used, the mask displayed or set is symbolic; otherwise, it is an
-octal number.
-.Pp
-Symbolic masks are like those used by
-.Xr chmod 1 .
-When used, they describe what permissions may be made available (as opposed to
-octal masks in which a set bit means the corresponding bit is to be cleared).
-For example,
-.Dq ug=rwx,o=
-sets the mask so files will not be readable, writable, or executable by
-.Dq others ,
-and is equivalent (on most systems) to the octal mask
-.Dq 007 .
+A
+.Em case conditional
+is used to run commands whenever a pattern is matched.
+Its format is:
+.Bd -unfilled -offset indent
+.No case Ar word No in
+.No " " Po Ar pattern Oo | Ar pattern ... Oc Pc Ar command Ns ;;
+.No " " Ar ...
+esac
+.Ed
.Pp
-.It Xo
-.Ic unalias
-.Op Fl adt
-.Op Ar name ...
-.Xc
-The aliases for the given names are removed.
-If the
-.Fl a
-option is used, all aliases are removed.
-If the
-.Fl t
-or
-.Fl d
-options are used, the indicated operations are carried out on tracked or
-directory aliases, respectively.
+In this case
+.Ar pattern
+is matched against the string resulting from the expansion of
+.Ar word .
+Multiple commands may be given by grouping them in lists,
+as described above,
+or by separating them with newlines.
+The initial
+.Sq (\&
+is optional,
+as is the terminating
+.Sq ;;
+for the final command.
+The exit status is zero if no patterns are matched
+or otherwise the exit status of the last command executed.
+.Pp
+An
+.Em if conditional
+is used to execute commands depending on the exit status of the command or
+command list being tested.
+Its format is:
+.Bd -unfilled -offset indent
+.No if Ar conditional
+then
+.No " " Ar command
+.No " " Ar ...
+.No elif Ar conditional
+then
+.No " " Ar command
+.No " " Ar ...
+.No else
+.No " " Ar command
+.No " " Ar ...
+fi
+.Ed
.Pp
-.It Xo
-.Ic unset
-.Op Fl fv
-.Ar parameter ...
-.Xc
-Unset the named parameters
-.Po
-.Fl v ,
-the default
-.Pc
-or functions
-.Pq Fl f .
-The exit status is non-zero if any of the parameters have the read-only
-attribute set, zero otherwise.
-.Pp
-.It Ic wait Op Ar job ...
-Wait for the specified job(s) to finish.
-The exit status of
-.Ic wait
-is that of the last specified job; if the last job is killed by a signal, the
-exit status is 128 + the number of the signal (see
-.Ic kill -l Ar exit-status
-above); if the last specified job can't be found (because it never existed, or
-had already finished), the exit status of
-.Ic wait
-is 127.
-See
-.Sx Job control
-below for the format of
-.Ar job .
-.Ic wait
-will return if a signal for which a trap has been set is received, or if a
-.Dv SIGHUP ,
-.Dv SIGINT ,
+Firstly the command(s) following
+.Qq if
+is executed;
+if its exit status is zero,
+the commands in the
+.Qq then
+block are executed and the conditional completes.
+Otherwise the commands in the
+.Qq elif
+block are executed;
+if the exit status is zero,
+the commands in the
+.Qq then
+block are executed and the conditional completes.
+Otherwise the next
+.Qq elif
+block, if any, is tried.
+If nothing from an
+.Qq if
or
-.Dv SIGQUIT
-signal is received.
-.Pp
-If no jobs are specified,
-.Ic wait
-waits for all currently running jobs (if any) to finish and exits with a zero
-status.
-If job monitoring is enabled, the completion status of jobs is printed
-(this is not the case when jobs are explicitly specified).
+.Qq elif
+block returns zero,
+the commands in the
+.Qq else
+block are run and the conditional completes.
+The
+.Qq elif
+and
+.Qq else
+blocks are optional.
.Pp
-.It Xo
-.Ic whence
-.Op Fl pv
-.Op Ar name ...
-.Xc
-For each
-.Ar name ,
-the type of command is listed (reserved word, built-in, alias,
-function, tracked alias, or executable).
-If the
-.Fl p
-option is used, a path search is performed even if
-.Ar name
-is a reserved word, alias, etc.
-Without the
-.Fl v
-option,
-.Ic whence
-is similar to
-.Ic command Fl v
-except that
-.Ic whence
-will find reserved words and won't print aliases as alias commands.
-With the
-.Fl v
-option,
-.Ic whence
-is the same as
-.Ic command Fl V .
-Note that for
-.Ic whence ,
-the
-.Fl p
-option does not affect the search path used, as it does for
-.Ic command .
-If the type of one or more of the names could not be determined, the exit
-status is non-zero.
-.El
-.Ss Job control
-Job control refers to the shell's ability to monitor and control jobs, which
-are processes or groups of processes created for commands or pipelines.
-At a minimum, the shell keeps track of the status of the background (i.e.\&
-asynchronous) jobs that currently exist; this information can be displayed
-using the
-.Ic jobs
-commands.
-If job control is fully enabled (using
-.Ic set -m
+Multiple commands may be given by grouping them in lists,
+as described above,
+or by separating them with newlines.
+The exit status is zero if nothing is executed from an
+.Qq if
or
-.Ic set -o monitor ) ,
-as it is for interactive shells, the processes of a job are placed in their
-own process group.
-Foreground jobs can be stopped by typing the suspend
-character from the terminal (normally ^Z), jobs can be restarted in either the
-foreground or background using the
-.Ic fg
-and
-.Ic bg
-commands, and the state of the terminal is saved or restored when a foreground
-job is stopped or restarted, respectively.
+.Qq elif
+block
+or otherwise the exit status of the last command executed.
+.Pp
+Functions allow the user to define a group of commands,
+executed whenever the function is invoked.
+Its format is:
+.Bd -unfilled -offset indent
+.Ar function Ns () Ar command-list
+.Ed
.Pp
-Note that only commands that create processes (e.g. asynchronous commands,
-subshell commands, and non-built-in, non-function commands) can be stopped;
-commands like
-.Ic read
-cannot be.
-.Pp
-When a job is created, it is assigned a job number.
-For interactive shells, this number is printed inside
-.Dq [..] ,
-followed by the process IDs of the processes in the job when an asynchronous
-command is run.
-A job may be referred to in the
-.Ic bg ,
-.Ic fg ,
-.Ic jobs ,
-.Ic kill ,
-and
-.Ic wait
-commands either by the process ID of the last process in the command pipeline
-(as stored in the
-.Ic $!\&
-parameter) or by prefixing the job number with a percent
-sign
-.Pq Sq % .
-Other percent sequences can also be used to refer to jobs:
-.Bl -tag -width "%+ | %% | %XX"
-.It %+ \*(Ba %% \*(Ba %
-The most recently stopped job, or, if there are no stopped jobs, the oldest
-running job.
-.It %-
-The job that would be the
-.Ic %+
-job if the latter did not exist.
-.It % Ns Ar n
-The job with job number
-.Ar n .
-.It %? Ns Ar string
-The job with its command containing the string
-.Ar string
-(an error occurs if multiple jobs are matched).
-.It % Ns Ar string
-The job with its command starting with the string
-.Ar string
-(an error occurs if multiple jobs are matched).
+The above simply defines a function;
+nothing is executed until the function is invoked.
+Commands may specify redirections
+and positional parameters are changed,
+for the duration of the function,
+to those passed to it.
+The special parameter
+.Sq #
+is temporarily changed too,
+though
+.Sq 0
+is not.
+After the function finishes,
+the positional parameters and
+.Sq #
+are restored to their original values.
+The exit status of a function definition is 0 if successful
+or >0 otherwise.
+The exit status of a function is that of the last command
+executed by the function.
+.Sh SPECIAL PARAMETERS
+Some parameters have special meaning to the shell
+and are listed below.
+.Bl -tag -width Ds
+.It 0
+The name of the shell or shell script.
+.It 1 ... n
+The
+.Em positional parameters .
+These parameters are set when a shell, shell script,
+or shell function is invoked.
+Each argument passed to a shell or shell script
+is assigned a positional parameter,
+starting at 1,
+and assigned sequentially.
+When a shell function is invoked,
+any arguments passed to it are temporarily reassigned to the
+positional parameters;
+when the function completes,
+the values are restored.
+Positional parameters 10 and above should be enclosed in {}.
+Positional parameters can be reassigned using the
+.Ic set
+command.
+.It @
+All positional parameters.
+Within double quotes,
+each parameter is output as a separate field.
+The resulting list completely matches what was passed to the shell.
+So "1 2" "3" is output as two parameters, "1 2" and "3".
+.It *
+All positional parameters.
+Within double quotes,
+all parameters are output as one field,
+separated by the first character of
+.Ev IFS
+(by default a space).
+The resulting list of words is amalgamated,
+losing the sense of how they were passed to the shell.
+So "1 2" "3" is output as one parameter, "1 2 3".
+.It #
+The number of positional parameters.
+.It ?
+The exit status of the most recent command.
+.It -
+The current shell options.
+.It $
+The process ID of the current shell.
+Subshells have the same PID as the current shell.
+.It !
+The process ID of the most recent background command.
.El
-.Pp
-When a job changes state (e.g. a background job finishes or foreground job is
-stopped), the shell prints the following status information:
-.Pp
-.D1 [ Ns Ar number ] Ar flag status command
-.Pp
-where...
-.Bl -tag -width "command"
-.It Ar number
-is the job number of the job;
-.It Ar flag
-is the
-.Ql +
-or
-.Ql -
-character if the job is the
-.Ic %+
+.Sh ENVIRONMENT
+The following environment variables affect the execution of
+.Nm :
+.Bl -tag -width "MAILCHECKXXX"
+.It Ev CDPATH
+Colon separated list of directories used by the
+.Ic cd
+command.
+.It Ev ENV
+Pathname to a file containing commands to be executed
+when an interactive shell is started.
+.It Ev FCEDIT
+Editor for the
+.Ic fc
+builtin.
+The default is
+.Xr ed 1 .
+.It Ev HISTFILE
+Pathname to a file to be used to record command history.
+The default is to not write command history to a file.
+.It Ev HISTSIZE
+The maximum number of commands stored in history.
+The default is 500.
+.It Ev HOME
+Pathname to a user's home directory.
+.It Ev IFS
+A list of characters to be used for field splitting.
+.It Ev LINENO
+The current line number in a script or function,
+starting at 1.
+This variable should not be set by users.
+.It Ev MAIL
+Pathname to a user's mailbox file.
+If set,
+.Nm
+reports the arrival of new mail
+(ascertained by checking a file's modification time)
+every
+.Ev MAILCHECK
+seconds.
+.Ev MAIL
+is overridden by
+.Ev MAILPATH .
+.It Ev MAILCHECK
+How often,
+in seconds,
+to check for new mail in either
+.Ev MAIL
or
-.Ic %-
-job, respectively, or space if it is neither;
-.It Ar status
-indicates the current state of the job and can be:
-.Bl -tag -width "RunningXX"
-.It Done Op Ar number
-The job exited.
-.Ar number
-is the exit status of the job, which is omitted if the status is zero.
-.It Running
-The job has neither stopped nor exited (note that running does not necessarily
-mean consuming CPU time \-
-the process could be blocked waiting for some event).
-.It Stopped Op Ar signal
-The job was stopped by the indicated
-.Ar signal
-(if no signal is given, the job was stopped by
-.Dv SIGTSTP ) .
-.It Ar signal-description Op Dq core dumped
-The job was killed by a signal (e.g. memory fault, hangup); use
-.Ic kill -l
-for a list of signal descriptions.
-The
-.Dq core dumped
-message indicates the process created a core file.
+.Ev MAILPATH .
+The default is 600 (10 minutes).
+If set to 0,
+check before issuing each prompt.
+.It Ev MAILPATH
+Pathname to a colon separated list of mailboxes.
+If set,
+.Nm
+reports the arrival of new mail
+(ascertained by checking a file's modification time)
+every
+.Ev MAILCHECK
+seconds.
+The default notification message
+.Pq Qq you have mail in $_
+can be changed per mailbox by appending
+.No % Ns Ar message
+to a pathname.
+.Ev MAILPATH
+overrides
+.Ev MAIL .
+.It Ev OLDPWD
+Pathname to the previous working directory.
+.It Ev OPTARG
+An option argument for the
+.Ic getopts
+command.
+.It Ev OPTIND
+An index to the next option for the
+.Ic getopts
+command.
+.It Ev PATH
+Pathname to a colon separated list of directories
+used to search for the location of executable files.
+A pathname of
+.Sq .\&
+represents the current working directory.
+The default value of
+.Ev PATH
+on
+.Ox
+is:
+.Bd -literal -offset 2n
+/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/local/bin
+.Ed
+.It Ev PPID
+The shell's parent process ID.
+Subshells have the same
+.Ev PPID
+as the parent of the current shell.
+.It Ev PS1
+User prompt displayed every time an interactive shell
+is ready to read a command.
+A
+.Sq !\&
+in the prompt is expanded to the number of the next command in history
+to be typed.
+The default value is
+.Sq $\ \&
+for normal users and
+.Sq #\ \&
+for root.
+.It Ev PS2
+Newline prompt displayed in an interactive shell
+when a newline has been entered
+before the command line completes.
+The default value is
+.Sq >\ \& .
+.It Ev PS4
+Trace prompt displayed in an interactive shell
+before each command is traced
+(see the
+.Fl x
+option).
+The default is
+.Sq +\ \& .
+.It PWD
+The absolute pathname to the current working directory.
+Assignments to this variable are ignored.
.El
-.It Ar command
-is the command that created the process.
-If there are multiple processes in
-the job, each process will have a line showing its
-.Ar command
-and possibly its
-.Ar status ,
-if it is different from the status of the previous process.
+.Sh ASYNCHRONOUS EVENTS
+The following signals affect the execution of
+.Nm :
+.Bl -tag -width "SIGQUITXXX"
+.It Dv SIGINT
+If a shell is interactive
+and in command line editing mode,
+editing is terminated on the current line
+and the command being edited is not entered into command history.
+Otherwise the signal is caught
+but no action is taken.
+.It Dv SIGQUIT
+Ignored if a shell is interactive.
+.It Dv SIGTERM
+Ignored if a shell is interactive.
+.It Dv SIGTSTP
+Ignored if a shell is interactive
+and the
+.Ic monitor
+option
+.Pq Fl m
+is set.
+.It Dv SIGTTIN
+Ignored if a shell is interactive
+and the
+.Ic monitor
+option
+.Pq Fl m
+is set.
+.It Dv SIGTTOU
+Ignored if a shell is interactive
+and the
+.Ic monitor
+option
+.Pq Fl m
+is set.
.El
-.Pp
-When an attempt is made to exit the shell while there are jobs in the stopped
-state, the shell warns the user that there are stopped jobs and does not exit.
-If another attempt is immediately made to exit the shell, the stopped jobs are
-sent a
-.Dv SIGHUP
-signal and the shell exits.
-Similarly, if the
-.Ic nohup
-option is not set and there are running jobs when an attempt is made to exit
-a login shell, the shell warns the user and does not exit.
-If another attempt
-is immediately made to exit the shell, the running jobs are sent a
-.Dv SIGHUP
-signal and the shell exits.
-.Sh FILES
-.Bl -tag -width "/etc/suid_profileXX" -compact
-.It Pa ~/.profile
-User's login profile.
-.It Pa /etc/profile
-System login profile.
-.It Pa /etc/suid_profile
-Privileged shell profile.
-.It Pa /etc/shells
-Shell database.
+.Sh EXIT STATUS
+The
+.Nm
+utility exits with one of:
+.Bl -tag -width "1-125"
+.It 0
+The script being executed contained only blank lines or comments.
+.It 1\(en125
+A non-interactive shell detected an error other than
+.Ar file
+not found.
+.It 126
+A command was found but was not executable.
+.It 127
+A non-interactive shell returned
+.Ar file
+not found.
.El
+.Pp
+Otherwise
+.Nm
+returns the exit status of the last command it invoked.
.Sh SEE ALSO
.Xr csh 1 ,
.Xr ed 1 ,
.Xr ksh 1 ,
-.Xr mg 1 ,
-.Xr stty 1 ,
.Xr vi 1 ,
-.Xr shells 5 ,
-.Xr environ 7 ,
.Xr script 7
-.Rs
-.%A Morris Bolsky
-.%A David Korn
-.%B The KornShell Command and Programming Language, 2nd Edition
-.%D 1995
-.%I Prentice Hall
-.%O ISBN 0131827006
-.Re
-.Rs
-.%A Stephen G. Kochan
-.%A Patrick H. Wood
-.%B UNIX Shell Programming, 3rd Edition
-.%D 2003
-.%I Sams
-.%O ISBN 0672324903
-.Re
-.Rs
-.%A IEEE Inc.
-.%D 1993
-.%O ISBN 1-55937-266-9
-.%T IEEE Standard for Information Technology \- Portable Operating \
- System Interface (POSIX) \- Part 2: Shell and Utilities
-.Re
-.Sh NOTES
-.Nm
-is implemented as a run-time option of
-.Nm pdksh ,
-with only those
-.Nm
-features whose syntax or semantics are incompatible with a traditional Bourne
-shell disabled.
-Since this leaves some
+.Sh STANDARDS
+The
.Nm
-extensions exposed, caution should be used where backwards compatibility with
-traditional Bourne or POSIX compliant shells is an issue.
-.Sh AUTHORS
-.An -nosplit
-This shell is based on the public domain 7th edition Bourne shell clone by
-.An Charles Forsyth
-and parts of the BRL shell by
-.An Doug A. Gwyn ,
-.An Doug Kingston ,
-.An Ron Natalie ,
-.An Arnold Robbins ,
-.An Lou Salkind ,
-and others.
-The first release of
-.Nm pdksh
-was created by
-.An Eric Gisin ,
-and it was subsequently maintained by
-.An John R. MacMillan Aq Mt change!john@sq.sq.com ,
-.An Simon J. Gerraty Aq Mt sjg@zen.void.oz.au ,
+utility is compliant with the
+.St -p1003.1-2008
+specification,
+except where noted below:
+.Bl -dash
+.It
+The flag
+.Op Fl h
+is documented by POSIX as hashing
+.Qq utilities invoked by functions as those functions are defined ;
+this implementation hashes utilities after first invocation
+(and functions be damned).
+.It
+POSIX says mail notifications via
+.Ev MAIL
and
-.An Michael Rendell Aq Mt michael@cs.mun.ca .
+.Ev MAILPATH
+should happen if a file is created,
+as well as if its modification time changes.
+This implementation of
+.Nm
+does not provide notification when these files are created.
+.It
+Command substitution occurring within double quotes
+is subject to pathname expansion but should not be.
+.It
+The built-in
+.Ic newgrp
+is unsupported.
+.It
The
-.Pa CONTRIBUTORS
-file in the source distribution contains a more complete list of people and
-their part in the shell's development.
-.\" .Sh BUGS
-.\" Any bugs in
-.\" .Nm pdksh
-.\" should be reported to pdksh@cs.mun.ca.
-.\" Please include the version of
-.\" .Nm pdksh
-.\" .Po
-.\" .Ic echo $KSH_VERSION
-.\" shows it
-.\" .Pc ,
-.\" the machine, operating system, and compiler you are using and a description of
-.\" how to repeat the bug (a small shell script that demonstrates the bug is best).
-.\" The following, if relevant (if you are not sure, include them), can also be
-.\" helpful: options you are using (both
-.\" .Pa options.h
-.\" and
-.\" .Ic set Fl o Ic options )
-.\" and a copy of your
-.\" .Pa config.h
-.\" (the file generated by the
-.\" .Pa configure
-.\" script).
-.\" New versions of
-.\" .Nm pdksh
-.\" can be obtained from ftp://ftp.cs.mun.ca/pub/pdksh.
-.\" .Pp
-.\" BTW, the most frequently reported bug is:
-.\" .Bd -literal -offset indent
-.\" $ echo hi | read a; echo $a # Does not print hi
-.\" .Ed
-.\" .Pp
-.\" I'm aware of this and there is no need to report it.
+.Ic break
+and
+.Ic continue
+built-ins should exit/return from the outermost loop if the argument
+.Ar n
+is greater than the level of loops.
+.El
