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-.\"	$OpenBSD: ksh.1tbl,v 1.90 2005/02/05 12:36:21 jmc Exp $
-.\"
-.\"	Public Domain
-.\"
-.Dd August 19, 1996
-.Dt KSH 1
-.Os
-.Sh NAME
-.Nm ksh
-.Nd public domain Korn shell
-.Sh SYNOPSIS
-.Nm ksh
-.Op Fl +abCefhiklmnprsuvxX
-.Op Fl +o Ar option
-.Xo
-.Bk -words
-.Oo Oo Fl c Ar command-string
-.Op Ar command-name
-.Li \&| Fl s
-.Li \&| Ar file Oc
-.Ek
-.Op Ar argument ... Oc
-.Xc
-.Sh DESCRIPTION
-.Nm
-is a command interpreter intended for both interactive and shell
-script use.
-Its command language is a superset of the
-.Xr sh 1
-shell language.
-.Ss Shell startup
-The following options can be specified only on the command line:
-.Bl -tag -width Ds
-.It Fl c Ar command-string
-.Nm
-will execute the command(s) contained in
-.Ar command-string .
-.It Fl i
-Interactive mode; see below.
-.It Fl l
-Login shell; see below.
-.It Fl s
-The shell reads commands from standard input; all non-option arguments
-are positional parameters.
-.It Fl r
-Restricted mode; see below.
-.El
-.Pp
-In addition to the above, the options described in the
-.Ic set
-built-in command can also be used on the command line.
-.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
-.Ic $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 name the shell was called with (i.e.,
-.Li argv[0] )
-is used.
-.Pp
-A shell is
-.Dq interactive
-if the
-.Fl i
-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 (if available), ignores the
-.Dv SIGINT ,
-.Dv SIGQUIT ,
-and
-.Dv SIGTERM
-signals, and prints prompts before reading input (see
-.Ev PS1
-and
-.Ev PS2
-parameters).
-For non-interactive shells, the
-.Ic trackall
-option is on by default (see the
-.Ic set
-command below).
-.Pp
-A shell is
-.Dq restricted
-if the
-.Fl r
-option is used or if either the basename of the name the shell was invoked
-with or the
-.Ev SHELL
-parameter match the pattern
-.Dq \&*r\&*sh
-(e.g.,
-.Dq rsh ,
-.Dq rksh ,
-.Dq rpdksh ,
-etc.).
-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 > ,
-.Ql >| ,
-.Ql >> ,
-.Ql <> ) .
-.El
-.Pp
-A shell is
-.Dq privileged
-if the
-.Fl p
-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).
-.Pp
-If the basename of the name the shell is called with (i.e.,
-.Li argv[0] )
-starts with
-.Ql -
-or if the
-.Fl l
-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.
-.Pp
-If the
-.Ev ENV
-parameter is set when the 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.
-If the
-.Ev ENV
-parameter is not set (and not
-.Dv NULL )
-and
-.Nm pdksh
-was compiled with the
-.Dv DEFAULT_ENV
-macro defined, the file named in that macro is included (after the above
-mentioned substitutions have been performed).
-.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 < ,
-.Ql > ,
-.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 tokens:
-.Ql < ,
-.Ql <& ,
-.Ql << ,
-.Ql > ,
-.Ql >& ,
-.Ql >> ,
-etc. are used to specify redirections (see
-.Sx Input/output redirection
-below);
-.Ql |
-is used to create pipelines;
-.Ql |&
-is used to create co-processes (see
-.Sx Co-processes
-below);
-.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;
-.Ql \&(\&( .. \&)\&)
-is used in arithmetic expressions;
-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);
-.Ql {
-and
-.Ql }
-delimit
-.Xr csh 1
-style alterations (see
-.Sx Brace 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).
-The
-.Ql |&
-operator starts a co-process which is a special kind of asynchronous process
-(see
-.Sx Co-processes
-below).
-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 center
-case     else     function then     !
-do       esac     if       time     [[
-done     fi       in       until    {
-elif     for      select   while    }
-.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,
-.Bd -unfilled -offset indent
-.Ic { echo foo; echo bar; }
-.Ic { echo foo; echo bar<newline> }
-.Ic { { echo foo; echo bar; } }
-.Ed
-.Pp
-are all valid, but
-.Bd -unfilled -offset indent
-.Ic { echo foo; echo bar }
-.Ed
-.Pp
-is not.
-.Bl -tag -width Ds
-.It Ic \&( Ar list Ic \&)
-Execute
-.Ar list
-in a subshell.
-There is no implicit way to pass environment changes from a
-subshell back to its parent.
-.It Ic \&{ Ar list Ic \&}
-Compound construct;
-.Ar list
-is executed, but not in a subshell.
-Note that
-.Ic \&{
-and
-.Ic \&}
-are reserved words, not meta-characters.
-.It Xo Ic case Ar word Ic in [
-.Ns [ Ic \&( ] Ar pattern [
-.Ns Ic \&| Ar pattern ] ... Ic \&)
-.Ar list Ic \&;\&;
-.Ns ] Ar ...
-.Ic esac
-.Xc
-The
-.Ic case
-statement attempts to match
-.Ar word
-against the specified
-.Ar pattern Ns s ;
-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 Ic for Ar name No [
-.Ic in Ar word ... term Ns ]
-.Ic do Ar list Ic 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
-.Po
-.Ic $1 , $2 ,
-etc.\&
-.Pc
-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.
-.Ar term
-is either a newline or a
-.Ql \&; .
-.It Xo Ic if Ar list Ic then
-.Ar list [ Ic elif Ar list Ic then
-.Ar list ] Ar ... [ Ic else
-.Ar list ] Ic 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 Ic select Ar name No [
-.Ic in Ar word ... term Ns ]
-.Ic do Ar list Ic 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
-.Dq #?\ \&
-.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 .
-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
-.Ic in Ar word ...\&
-is omitted, the positional parameters are used (i.e.,
-.Ic $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 Ic until Ar list Ic do Ar list
-.Ic 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 Ic while Ar list Ic do Ar list
-.Ic 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 Ic function Ar name Ic \&{
-.Ar list Ic \&}
-.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 Ic () Ar command
-Mostly the same as
-.Ic function
-(see
-.Sx Functions
-below).
-.It Xo Ic time Op Fl p
-.Op Ar pipeline
-.Xc
-The
-.Ic time
-reserved word is described in the
-.Sx Command execution
-section.
-.It Ic (( Ar expression Ic ))
-The arithmetic expression
-.Ar expression
-is evaluated; equivalent to
-.Ic let Ar expression
-(see
-.Sx Arithmetic expressions
-and the
-.Ic let
-command below).
-.It Ic [[ Ar expression Ic ]]
-Similar to the
-.Ic test
-and
-.Ic \&[ Ar ... 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 Tn AND
-and
-.Fl o
-.Pq Tn OR
-operators are replaced with
-.Ql &&
-and
-.Ql || ,
-respectively.
-.It
-Operators (e.g.,
-.Sq Fl f ,
-.Sq = ,
-.Sq \&! ,
-etc.) 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 <
-and
-.Ql >
-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
-.Ic \&[ Ar str Ic \&]
-use
-.Ic \&[[ Fl n Ar str Ic \&]] ) .
-.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 statement
-.Pp
-.Dl Ic "[[ -r foo && $(< foo) = b*r ]]"
-.Pp
-the
-.Ic $(< foo)
-is evaluated if and only if the file
-.Pa foo
-exists and is readable.
-.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 sequences of the form
-.Ic \&"...`...\e\&"...`..\&" .
-.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:
-.Pp
-.Bl -item -offset indent -compact
-.It
-.Ic autoload='typeset -fu'
-.It
-.Ic functions='typeset -f'
-.It
-.Ic hash='alias -t'
-.It
-.Ic history='fc -l'
-.It
-.Ic integer='typeset -i'
-.It
-.Ic local='typeset'
-.It
-.Ic login='exec login'
-.It
-.Ic nohup='nohup '
-.It
-.Ic r='fc -e -'
-.It
-.Ic stop='kill -STOP'
-.It
-.Ic suspend='kill -STOP $$'
-.It
-.Ic type='whence -v'
-.El
-.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 Fl o Ic trackall
-or
-.Ic set Fl 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:
-.Ic cat , cc , chmod , cp ,
-.Ic date , ed , emacs , grep ,
-.Ic ls , mail , make , mv ,
-.Ic pr , rm , sed , sh ,
-.Ic vi ,
-and
-.Ic who .
-.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
-.Ic $ Ns Ar name
-or
-.Ic ${ Ns Ar ... Ns Ic \&} ;
-command substitutions take the form
-.Ic $( Ns Ar command Ns Ic \&)
-or
-.Ic ` Ns Ar command Ns Ic ` ;
-and arithmetic substitutions take the form
-.Ic $(( Ns Ar expression Ns Ic )) .
-.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 <space>: ,
-the sequence of characters
-.Dq <space>A<space>:<space><space>B::D
-contains 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
-The results of substitution are, unless otherwise specified, also subject to
-brace expansion and file name expansion (see the relevant sections below).
-.Pp
-A command substitution is replaced by the output generated by the specified
-command, which is run in a subshell.
-For
-.Ic $( Ns Ar command Ns Ic \&)
-substitutions, normal quoting rules are used when
-.Ar command
-is parsed; however, for the
-.Ic ` Ns Ar command Ns Ic `
-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
-.Ic \&< Ar file
-is interpreted to mean substitute the contents of
-.Ar file
-(note that
-.Ic $(< foo)
-has the same effect as
-.Ic $(cat foo) ,
-but it is carried out more efficiently because no process is started).
-.Pp
-.Sy Note:
-.Ic $( Ns Ar command Ns Ic \&)
-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 .
-The latter form can be treated as arrays by appending an array index of the
-form
-.Op Ar expr
-where
-.Ar expr
-is an arithmetic expression.
-Array indices are currently limited to the range 0 through 1023, inclusive.
-Parameter substitutions take the form
-.Ic $ Ns Ar name ,
-.Ic ${ Ns Ar name Ns Ic \&} ,
-or
-.Sm off
-.Xo
-.Ic ${ Ar name Oo Ar expr Oc
-.Ic \&} ,
-.Xc
-.Sm on
-where
-.Ar name
-is a parameter name.
-If substitution is performed on a parameter
-(or an array parameter element)
-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
-.Ic # , PWD ,
-etc.; 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
-.Ev 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 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
-and
-.Ic select
-loops set parameters as well as the
-.Ic getopts ,
-.Ic read
-and
-.Ic set Fl A
-commands.
-Lastly, parameters can be assigned values using assignment operators
-inside arithmetic expressions (see
-.Sx Arithmetic expressions
-below) or using the
-.Xo Ic ${ Ns Ar name Ns =
-.Ns Ar value Ns Ic \&}
-.Xc
-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
-.Ic ${ Ns Ar name Ns Ic \&}
-form of parameter substitution:
-.Bl -tag -width Ds
-.It Xo Ic ${ Ns Ar name Ns
-.Ic \&:\&- Ns Ar word Ns Ic \&}
-.Xc
-If
-.Ar name
-is set and not
-.Dv NULL ,
-it is substituted; otherwise,
-.Ar word
-is substituted.
-.It Xo Ic ${ Ns Ar name Ns
-.Ic \&:\&+ Ns Ar word Ns Ic \&}
-.Xc
-If
-.Ar name
-is set and not
-.Dv NULL ,
-.Ar word
-is substituted; otherwise, nothing is substituted.
-.It Xo Ic ${ Ns Ar name Ns
-.Ic \&:\&= Ns Ar word Ns Ic \&}
-.Xc
-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.
-.It Xo Ic ${ Ns Ar name Ns
-.Ic \&:\&? Ns Ar word Ns Ic \&}
-.Xc
-If
-.Ar name
-is set and not
-.Dv NULL ,
-it is substituted; otherwise,
-.Ar word
-is printed on standard error (preceded by
-.Ar name Ns \&: )
-and an error occurs (normally causing termination of a shell script, function
-or .-script).
-If 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:
-.Bl -tag -width Ds
-.It Ic ${# Ns Ar name Ns Ic \&}
-The number of positional parameters if
-.Ar name
-is
-.Ql * ,
-.Ql @ ,
-not specified, or the length of the string value of parameter
-.Ar name .
-.It Xo Ic ${# Ns Ar name Ns
-.Ic [*\&]} , ${# Ns Ar name Ns Ic [@\&]}
-.Xc
-The number of elements in the array
-.Ar name .
-.Sm off
-.It Xo
-.Ic ${ Ar name Ic # Ar pattern
-.Sm on
-.Ic } ,
-.Sm off
-.Ic ${ Ar name Ic ## Ar pattern Ic \&}
-.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.
-.Sm off
-.It Xo
-.Ic ${ Ar name Ic % Ar pattern
-.Sm on
-.Ic } ,
-.Sm off
-.Ic ${ Ar name Ic %% Ar pattern Ic }
-.Xc
-.Sm on
-Like
-.Ic ${..#..}
-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 (i.e.,
-.Ic $1 , $2 ,
-etc.).
-.It Ev \&$
-The process ID of the shell, or the
-.Tn 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 the shell was invoked with (i.e.,
-.Li argv[0] ) ,
-or the
-.Ar command-name
-if it was invoked with the
-.Fl c
-option and the
-.Ar command-name
-was supplied, or the
-.Ar file
-argument, if it was supplied.
-If the
-.Ic posix
-option is not set,
-.Ic \&$0
-is the name of the current function or script.
-.It Ev 1 ... Ev 9
-The first nine positional parameters that were supplied to the shell, function
-or .-script.
-Further positional parameters may be accessed using
-.Ic ${ Ns Ar number Ns Ic \&} .
-.It Ev \&*
-All positional parameters (except parameter 0); i.e.,
-.Ic $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 \&_ No (underscore)
-When an external command is executed by the shell, this parameter is set in the
-environment of the new process to the path of the executed command.
-In interactive use, this parameter is also set in the parent shell to the last
-word of the previous command.
-When
-.Ev MAILPATH
-messages are evaluated, this parameter contains the name of the file that
-changed (see
-.Ev MAILPATH
-parameter below).
-.It Ev CDPATH
-Search path for the
-.Ic cd
-built-in command.
-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
-.Dq \&.
-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 interactive line editing modes, and by the
-.Ic select ,
-.Ic set Fl o ,
-and
-.Ic kill Fl l
-commands to format information columns.
-.It Ev EDITOR
-If the
-.Ev VISUAL
-parameter is not set, this parameter controls the command-line editing mode for
-interactive shells.
-See
-.Ev VISUAL
-parameter below for how this works.
-.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 HISTFILE
-The name of the file used to store command history.
-When assigned to, history is loaded from the specified file.
-Also, several invocations of the shell
-running on the same machine will share history if their
-.Ev HISTFILE
-parameters all point to the same file.
-.Pp
-.Sy Note:
-If
-.Ev HISTFILE
-isn't set, no history file is used.
-This is different from the original Korn shell, which uses
-.Pa $HOME/.sh_history ;
-in the future,
-.Nm pdksh
-may also use a default history file.
-.It Ev HISTSIZE
-The number of commands normally stored for history.
-The default is 500.
-.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 KSH_VERSION
-The version of the shell and the date the version was created (read-only).
-See also the version commands in
-.Sx Emacs editing mode
-and
-.Sx Vi editing mode
-sections, below.
-.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.
-Not yet implemented.
-.It Ev MAIL
-If set, the user will be informed of the arrival of mail in the named file.
-This parameter is ignored if the
-.Ev MAILPATH
-parameter is set.
-.It Ev MAILCHECK
-How often, in seconds, the shell will check for mail in the file(s) specified
-by
-.Ev MAIL
-or
-.Ev MAILPATH .
-If set to 0, the shell checks before each prompt.
-The default is 600 (10 minutes).
-.It Ev MAILPATH
-A list of files to be checked for mail.
-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,
-the parameter
-.Ic $_
-contains the name of the file.
-The default message is
-.Dq you have mail in $_ .
-.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 last argument processed when using
-.Ic getopts .
-Assigning 1 to this parameter causes
-.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 .'d files.
-An empty string resulting from a leading or trailing
-colon, or two adjacent colons, is treated as a
-.Dq \&. ,
-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,
-and the prompt string can be customised using
-backslash-escaped special characters (see below).
-.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 .
-.Pp
-Note that since the command-line editors try to figure out how long the prompt
-is (so they know how far it is to the edge of the screen), escape codes in
-the prompt tend to mess things up.
-You can tell the shell not to count certain
-sequences (such as escape codes) by using the
-.Li \e[ Ns Ar ... Ns Li \e]
-substitution (see below) or by prefixing your prompt with a non-printing
-character (such as control-A) followed by a carriage return and then delimiting
-the escape codes with this non-printing character.
-By the way, don't blame me for
-this hack; it's in the original
-.Xr ksh .
-The default is
-.Dq \&$\ \&
-for non-root users,
-.Dq \&#\ \&
-for root.
-.Pp
-The following backslash-escaped special characters can be used
-to customise the prompt:
-.Pp
-.Bl -tag -width "\eD{format}XX" -compact
-.It Li \ea
-Insert an ASCII bell character.
-.It Li \ed
-The current date, in the format
-.Dq Day Month Date
-for example
-.Dq Wed Nov 03 .
-.It Li \eD{ Ns Ar format Ns Li }
-The current date, with
-.Ar format
-converted by
-.Xr strftime 3 .
-The braces must be specified.
-.It Li \ee
-Insert an ASCII escape character.
-.It Li \eh
-The hostname, minus domain name.
-.It Li \eH
-The full hostname, including domain name.
-.It Li \ej
-Current number of jobs running
-(see
-.Sx Job control ,
-below).
-.It Li \el
-The controlling terminal.
-.It Li \en
-Insert a newline character.
-.It Li \er
-Insert a carriage return character.
-.It Li \es
-The name of the shell.
-.It Li \et
-The current time, in 24-hour HH:MM:SS format.
-.It Li \eT
-The current time, in 12-hour HH:MM:SS format.
-.It Li \e@
-The current time, in 12-hour HH:MM:SS AM/PM format.
-.It Li \eA
-The current time, in 24-hour HH:MM format.
-.It Li \eu
-The current user's username.
-.It Li \ev
-The current version of
-.Nm .
-.It Li \eV
-Like \ev, but more verbose.
-.It Li \ew
-The current working directory.
-.It Li \eW
-The basename of
-the current working directory.
-.It Li \e!
-The current history number
-(see
-.Li \e# ,
-below).
-Note: this sequence is not yet implemented.
-.It Li \e#
-The current command number.
-This could be different to the current history number,
-if
-.Ev HISTFILE
-contains a history list from a previous session.
-.It Li \e$
-The default prompt i.e.\&
-.Dq # \&
-if the effective UID is 0,
-otherwise
-.Dq $ \& .
-Note: this sequence is not yet implemented.
-.It Li \e Ns Ar nnn
-The octal character
-.Ar nnn .
-.It Li \e\e
-Insert a single backslash character.
-Note: this sequence is not yet implemented.
-.It Li \e[
-Normally the shell keeps track of the number of characters in the prompt.
-Use of this sequence turns off that count.
-.It Li \e]
-Use of this sequence turns the count back on.
-.El
-.Pp
-Note that the backslash itself may be interpreted by the shell.
-Hence, to set
-.Ev PS1
-either escape the backslash itself,
-or use double quotes.
-The latter is more practical:
-.Bd -literal -offset indent
-PS1="\eu "
-.Ed
-.Pp
-This is a more complex example,
-which does not rely on the above backslash-escaped sequences.
-It embeds the current working directory,
-in reverse video,
-in the prompt string:
-.Bd -literal -offset indent
-x=$(print \e\e001)
-PS1="$x$(print \e\er)$x$(tput so)$x\e$PWD$x$(tput se)$x> "
-.Ed
-.It Ev PS2
-Secondary prompt string, by default
-.Dq \&>\ \& ,
-used when more input is needed to complete a command.
-.It Ev PS3
-Prompt used by the
-.Ic select
-statement when reading a menu selection.
-Default is
-.Dq \&#\&?\ \& .
-.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.
-Default is
-.Dq \&+\ \& .
-.It Ev PWD
-The current working directory.
-May be unset or
-.Dv NULL
-if the shell doesn't know where it is.
-.It Ev RANDOM
-A random number generator.
-Every time
-.Ev RANDOM
-is referenced, it is assigned the next random number in the range
-0\-32767.
-By default,
-.Xr arc4random 3
-is used to produce values.
-If the variable
-.Ev RANDOM
-is assigned a value, the value is used as seed to
-.Xr srand 3
-and subsequent references of
-.Ev RANDOM
-will use
-.Xr rand 3
-to produce values, resulting in a predictable sequence.
-.It Ev REPLY
-Default parameter for the
-.Ic read
-command if no names are given.
-Also used in
-.Ic select
-loops to store the value that is read from standard input.
-.It Ev SECONDS
-The number of seconds since the shell started or, if the parameter has been
-assigned an integer value, the number of seconds since the assignment plus the
-value that was assigned.
-.It Ev TMOUT
-If set to a positive integer in an interactive shell, it specifies the maximum
-number of seconds the shell will wait for input after printing the primary
-prompt
-.Pq Ev PS1 .
-If the time is exceeded, the shell exits.
-.It Ev TMPDIR
-The directory shell temporary 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 .
-.It Ev VISUAL
-If set, this parameter controls the command-line editing mode for interactive
-shells.
-If the last component of the path specified in this parameter contains
-the string
-.Dq vi ,
-.Dq emacs
-or
-.Dq gmacs ,
-the
-.Xr vi ,
-.Xr emacs
-or
-.Xr gmacs
-(Gosling emacs) editing mode is enabled, respectively.
-.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 (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 unquoted colon
-.Pq Sq \&: ,
-and 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 Brace expansion (alteration)
-Brace expressions, which take the form
-.Bd -unfilled -offset indent
-.Sm off
-.Xo Ar prefix Ic { Ar str No 1,...,
-.Ar str No N Ic } Ar suffix
-.Xc
-.Sm on
-.Ed
-.Pp
-are expanded to N words, each of which is the concatenation of
-.Ar prefix ,
-.Ar str Ns i
-and
-.Ar suffix
-(e.g.,
-.Dq a{c,b{X,Y},d}e
-expands to four words:
-.Dq ace ,
-.Dq abXe ,
-.Dq abYe ,
-and
-.Dq ade ) .
-As noted in the example, brace expressions can be nested and the resulting
-words are not sorted.
-Brace expressions must contain an unquoted comma
-.Pq Sq \&,
-for expansion to occur (i.e.,
-.Ic {}
-and
-.Ic {foo}
-are not expanded).
-Brace expansion is carried out after parameter substitution
-and before file name generation.
-.Ss File name patterns
-A file name pattern is a word containing one or more unquoted
-.Ql \&?
-or
-.Ql *
-characters or
-.Dq [..]
-sequences.
-Once brace expansion has been performed, 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 Ic \&?
-Matches any single character.
-.It Ic \&*
-Matches any sequence of characters.
-.It Ic \&[ Ns .. Ns Ic \&]
-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
-.Dq 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.
-.It Ic \&[\&! Ns .. Ns Ic \&]
-Like
-.Ic \&[ Ns .. Ns Ic \&] ,
-except it matches any character not inside the brackets.
-.Sm off
-.It Xo Ic \&*( Ar pattern Ic \&| No \ ...\ 
-.Ic \&| Ar pattern Ic \&)
-.Xc
-.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 Xo Ic \&+( Ar pattern Ic \&| No \ ...\ 
-.Ic \&| Ar pattern Ic \&)
-.Xc
-.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 Xo Ic \&?( Ar pattern Ic \&| No \ ...\ 
-.Ic \&| Ar pattern Ic \&)
-.Xc
-.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 Xo Ic \&@( Ar pattern Ic \&| No \ ...\ 
-.Ic \&| Ar pattern Ic \&)
-.Xc
-.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 Xo Ic \&!( Ar pattern Ic \&| No \ ...\ 
-.Ic \&| Ar pattern Ic \&)
-.Xc
-.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
-.Dq \&.
-and
-.Dq \&.\&. ,
-but the original
-.Xr ksh ,
-Bourne
-.Xr sh ,
-and
-.Xr 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
-.Ic \&[ Ns .. Ns Ic \&]
-sequence; also, the names
-.Dq \&.
-and
-.Dq \&.\&.
-are never matched, even by the pattern
-.Dq \&.\&* .
-.Pp
-If the
-.Ic markdirs
-option is set, any directories that result from file name generation are marked
-with a trailing
-.Ql / .
-.Pp
-The
-.Tn POSIX
-character classes (i.e.,
-.Ic \&[\&: Ns Ar class-name Ns Ic \&:\&]
-inside a
-.Ic \&[ Ns .. Ns Ic \&]
-expression) are not yet implemented.
-.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 Ic \&> 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 < foo > 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 Ic \&>\&| Ar file
-Same as
-.Ic \&> ,
-except the file is truncated, even if the
-.Ic noclobber
-option is set.
-.It Ic \&>\&> Ar file
-Same as
-.Ic \&> ,
-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 Ic \&< Ar file
-Standard input is redirected from
-.Ar file ,
-which is opened for reading.
-.It Ic \&<\&> Ar file
-Same as
-.Ic \&< ,
-except the file is opened for reading and writing.
-.It Ic \&<\&< 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 Ic \&<\&<\&- Ar marker
-Same as
-.Ic \&<\&< ,
-except leading tabs are stripped from lines in the here document.
-.It Ic \&<\&& 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 Ic \&>\&& Ar fd
-Same as
-.Ic \&<\&& ,
-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
-.Pp
-.Dl Ic cat /foo/bar 2\*(Gt&1 \*(Gt /dev/null \&| cat -n
-.Pp
-will print an error with a line number prepended to it.
-.Ss Arithmetic expressions
-Integer arithmetic expressions can be used with the
-.Ic let
-command, inside
-.Ic $(( Ns .. Ns Ic ))
-expressions, inside array references (e.g.,
-.Sm off
-.Ar name Ic \&[ Ar expr Ic \&] ) ,
-.Sm on
-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:
-.Bl -item -offset indent -compact
-.It
-.Ic \&+ \&- \&! \&~ \&+\&+ \&-\&-
-.El
-.Pp
-Binary operators:
-.Bl -item -offset indent -compact
-.It
-.Ic \&,
-.It
-.Ic = \&*= /= %= \&+= \&-= \&<\&<=
-.Ic \&>\&>= \&&= ^= \&|=
-.It
-.Ic \&|\&|
-.It
-.Ic \&&\&&
-.It
-.Ic \&|
-.It
-.Ic ^
-.It
-.Ic \&&
-.It
-.Ic == \&!=
-.It
-.Ic \&< \&<= \&>= \&>
-.It
-.Ic \&<\&< \&>\&>
-.It
-.Ic \&+ \&-
-.It
-.Ic \&* / %
-.El
-.Pp
-Ternary operators:
-.Bl -item -offset indent -compact
-.It
-.Ic \&?\&:
-(precedence is immediately higher than assignment)
-.El
-.Pp
-Grouping operators:
-.Bl -item -offset indent -compact
-.It
-.Ic \&( \&)
-.El
-.Pp
-Integer constants may be specified with arbitrary bases using the notation
-.Ar base Ns Ic \&# 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 Ic \&+
-Result is the argument (included for completeness).
-.It unary Ic \&-
-Negation.
-.It Ic \&!
-Logical
-.Tn NOT ;
-the result is 1 if argument is zero, 0 if not.
-.It Ic \&~
-Arithmetic (bit-wise)
-.Tn NOT .
-.It Ic \&+\&+
-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 Ic \&-\&-
-Similar to
-.Ic \&+\&+ ,
-except the parameter is decremented by 1.
-.It Ic \&,
-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 Ic =
-Assignment; variable on the left is set to the value on the right.
-.It Xo Ic \&*= /= \&+= \&-= \&<\&<=
-.Ic \&>\&>= \&&= ^= \&|=
-.Xc
-Assignment operators.
-.Ao Ar var Ac
-.Ao Ar op Ac =
-.Ao Ar expr Ac
-is the same as
-.Ao Ar var Ac =
-.Ao Ar var Ac
-.Ao Ar op Ac
-.Ic \&(
-.Ao Ar expr Ac
-.Ic \&) .
-.It Ic \&|\&|
-Logical
-.Tn 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 Ic \&&\&&
-Logical
-.Tn 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 Ic \&|
-Arithmetic (bit-wise)
-.Tn OR .
-.It Ic ^
-Arithmetic (bit-wise)
-.Tn XOR
-(exclusive-OR).
-.It Ic \&&
-Arithmetic (bit-wise)
-.Tn AND .
-.It Ic ==
-Equal; the result is 1 if both arguments are equal, 0 if not.
-.It Ic \&!=
-Not equal; the result is 0 if both arguments are equal, 1 if not.
-.It Ic \&<
-Less than; the result is 1 if the left argument is less than the right, 0 if
-not.
-.It Ic \&<= \&>= \&>
-Less than or equal, greater than or equal, greater than.
-See
-.Ic \&< .
-.It Ic \&<\&< \&>\&>
-Shift left (right); the result is the left argument with its bits shifted left
-(right) by the amount given in the right argument.
-.It Ic \&+ \&- \&* /
-Addition, subtraction, multiplication, and division.
-.It Ic %
-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 Ao Ar arg1 Ac Ic \ \&?
-.Ao Ar arg2 Ac Ic \ \&: Ao Ar arg3 Ac
-.Xc
-.No If Ao Ar arg1 Ac
-is non-zero, the result is
-.Ao Ar arg2 Ac ,
-otherwise
-.Ao Ar arg3 Ac .
-.El
-.Ss Co-processes
-A co-process, which is a pipeline created with the
-.Ic \&|\&&
-operator, is an asynchronous process that the shell can both write to (using
-.Ic print -p )
-and read from (using
-.Ic read -p ) .
-The input and output of the co-process can also be manipulated using
-.Ic \&>\&&p
-and
-.Ic \&<\&&p
-redirections, respectively.
-Once a co-process has been started, another can't
-be started until the co-process exits, or until the co-process's input has been
-redirected using an
-.Ic exec Ar n Ns Ic \&>\&&p
-redirection.
-If a co-process's input is redirected in this way, the next
-co-process to be started will share the output with the first co-process,
-unless the output of the initial co-process has been redirected using an
-.Ic exec Ar n Ns Ic \&<\&&p
-redirection.
-.Pp
-Some notes concerning co-processes:
-.Bl -bullet
-.It
-The only way to close the co-process's input (so the co-process reads an
-end-of-file) is to redirect the input to a numbered file descriptor and then
-close that file descriptor (e.g.,
-.Ic exec 3\&>\&&p\&; exec 3\&>\&&\&- ) .
-.It
-In order for co-processes to share a common output, the shell must keep the
-write portion of the output pipe open.
-This means that end-of-file will not be
-detected until all co-processes sharing the co-process's output have exited
-(when they all exit, the shell closes its copy of the pipe).
-This can be
-avoided by redirecting the output to a numbered file descriptor (as this also
-causes the shell to close its copy).
-Note that this behaviour is slightly
-different from the original Korn shell which closes its copy of the write
-portion of the co-process output when the most recently started co-process
-(instead of when all sharing co-processes) exits.
-.It
-.Ic print -p
-will ignore
-.Dv SIGPIPE
-signals during writes if the signal is not being trapped or ignored; the same
-is true if the co-process input has been duplicated to another file descriptor
-and
-.Ic print -u Ns Ar n
-is used.
-.El
-.Ss Functions
-Functions are defined using either Korn shell
-.Ic function Ar name
-syntax or the Bourne/POSIX shell
-.Fn name
-syntax (see below for the difference between the two forms).
-Functions are like
-.Li .-scripts
-in that they are executed in the current environment.
-However, unlike
-.Li .-scripts ,
-shell arguments (i.e., positional parameters
-.Ic $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
-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
-.Ic $0
-parameter is set to the name of the function (Bourne-style functions
-leave
-.Ic $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
-.Dv OPTIND
-untouched, so using
-.Ic getopts
-inside a function interferes with using
-.Ic getopts
-outside the function).
-In the future, the following differences will also be added:
-.Bl -bullet -offset indent
-.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
-.El
-.Ss POSIX mode
-The shell is intended to be
-.Tn POSIX
-compliant; however, in some cases,
-.Tn 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 Fl o Ic posix .
-If it is on, the
-.Tn 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
-.Dv POSIXLY_CORRECT
-parameter. (The shell can also be compiled so that it is in
-.Tn 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
-Occurrences of
-.Ic \e\&"
-inside double quoted
-.Ic `\&.\&.`
-command substitutions.
-In
-.Tn POSIX
-mode, the
-.Ic \e\&"
-is interpreted when the command is interpreted; in
-.Pf non- Tn POSIX
-mode, the
-backslash is stripped before the command substitution is interpreted.
-For example,
-.Ic echo \&"`echo \e\&"hi\e\&"`\&"
-produces
-.Dq \&"hi\&"
-in
-.Tn POSIX
-mode,
-.Dq hi
-in
-.Pf non- Tn POSIX
-mode.
-To avoid problems, use the
-.Ic $(...)\&
-form of command substitution.
-.It
-.Ic kill -l
-output.
-In
-.Tn POSIX
-mode, signal names are listed one per line; in
-.Pf non- Tn 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 fg
-exit status.
-In
-.Tn POSIX
-mode, the exit status is 0 if no errors occur; in
-.Pf non- Tn POSIX
-mode, the exit status is that of the last foregrounded job.
-.It
-.Ic eval
-exit status.
-If
-.Ic eval
-gets to see an empty command (i.e.,
-.Ic eval "`false`" ) ,
-its exit status in
-.Tn POSIX
-mode will be 0.
-In
-.Pf non- Tn POSIX
-mode, it will be the exit status of the last command substitution that was
-done in the processing of the arguments to
-.Ic eval
-(or 0 if there were no command substitutions).
-.It
-.Ic getopts .
-In
-.Tn POSIX
-mode, options must start with a
-.Ql - ;
-in
-.Pf non- Tn POSIX
-mode, options can start with either
-.Ql -
-or
-.Ql + .
-.It
-Brace expansion (also known as alternation).
-In
-.Tn POSIX
-mode, brace expansion is
-disabled; in
-.Pf non- Tn POSIX
-mode, brace expansion is enabled.
-Note that
-.Ic set Fl o Ic posix
-(or setting the
-.Ev POSIXLY_CORRECT
-parameter) automatically turns the
-.Ic braceexpand
-option off; however, it can be explicitly turned on later.
-.It
-.Ic set \&- .
-In
-.Tn POSIX
-mode, this does not clear the
-.Ic verbose
-or
-.Ic xtrace
-options; in
-.Pf non- Tn POSIX
-mode, it does.
-.It
-.Ic set
-exit status.
-In
-.Tn POSIX
-mode, the exit status of
-.Ic set
-is 0 if there are no errors; in
-.Pf non- Tn POSIX
-mode, the exit status is that of any
-command substitutions performed in generating the
-.Ic set
-command.
-For example,
-.Ic set \&-\&- `false`; echo $?\&
-prints 0 in
-.Tn POSIX
-mode, 1 in
-.Pf non- Tn POSIX
-mode.
-This construct is used in most shell scripts that use the old
-.Xr getopt 1
-command.
-.It
-Argument expansion of the
-.Ic alias ,
-.Ic export ,
-.Ic readonly ,
-and
-.Ic typeset
-commands.
-In
-.Tn POSIX
-mode, normal argument expansion is done; in
-.Pf non- Tn POSIX
-mode,
-field splitting, file globbing, brace expansion, and (normal) tilde expansion
-are turned off, while assignment tilde expansion is turned on.
-.It
-Signal specification.
-In
-.Tn POSIX
-mode, signals can be specified as digits, only
-if signal numbers match
-.Tn POSIX
-values (i.e., HUP=1, INT=2, QUIT=3, ABRT=6,
-KILL=9, ALRM=14, and TERM=15); in
-.Pf non- Tn POSIX
-mode, signals can always be digits.
-.It
-Alias expansion.
-In
-.Tn POSIX
-mode, alias expansion is only carried out when
-reading command words; in
-.Pf non- Tn POSIX
-mode, alias expansion is carried out on any
-word following an alias that ended in a space.
-For example, the following
-.Ic for
-loop
-.Pp
-.Bl -item -offset indent -compact
-.It
-.Ic alias a='for ' i='j'
-.It
-.Xo
-.Ic a i in 1 2; do echo i=$i j=$j;
-.Ic done
-.Xc
-.El
-.Pp
-uses parameter
-.Ic i
-in
-.Tn POSIX
-mode,
-.Ic j
-in
-.Pf non- Tn POSIX
-mode.
-.It
-Test.
-In
-.Tn POSIX
-mode, the expression
-.Sq Fl t
-(preceded by some number of
-.Sq Ic \&!
-arguments) is always true as it is a non-zero length string; in
-.Pf non- Tn 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).
-.El
-.Ss Strict Bourne shell mode
-When the
-.Ic sh
-option is enabled (see the
-.Ic set
-command),
-.Nm
-will behave like
-.Xr sh 1
-in the following ways:
-.Bl -bullet
-.It
-The parameter
-.Ic $_
-is not set to
-.Bl -dash
-.It
-the expanded alias' full program path after entering commands
-that are tracked aliases,
-.It
-the last argument on the command line after entering external
-commands, or
-.It
-the file that changed when
-.Ev MAILPATH
-is set to monitor a mailbox.
-.El
-.It
-File descriptors are left untouched when executing
-.Ic exec
-with no arguments.
-.It
-Backslash-escaped special characters are not substituted in
-.Ev PS1 .
-.It
-Sequences of
-.Sq Li (( Ns Ar ... Ns Li ))
-are not interpreted as arithmetic expressions.
-.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, and 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, brace expansion, 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
-.Tn POSIX
-differ somewhat in which commands are considered
-special or regular:
-.Pp
-.Tn POSIX
-special commands
-.Pp
-.Ic \&. , \&: , break , continue ,
-.Ic eval , exec , exit , export ,
-.Ic readonly , return , set , shift ,
-.Ic trap , unset
-.Pp
-Additional
-.Nm
-special commands
-.Pp
-.Ic builtin , times , typeset
-.Pp
-Very special commands
-.Pq Pf non- Tn POSIX
-.Pp
-.Ic alias , readonly , set , typeset
-.Pp
-.Tn POSIX
-regular commands
-.Pp
-.Ic alias , bg , cd , command ,
-.Ic false , fc , fg , getopts ,
-.Ic jobs , kill , read , true ,
-.Ic umask , unalias , wait
-.Pp
-Additional
-.Nm
-regular commands
-.Pp
-.Ic \&[ , echo , let , print ,
-.Ic pwd , test , ulimit , whence
-.Pp
-In the future, the additional
-.Nm
-special and regular commands may be treated
-differently from the
-.Tn POSIX
-special and regular commands.
-.Pp
-Once the type of the 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:
-.Bl -tag -width Ds
-.It Ic \&. Ar file Op Ar arg1 ...
-Execute the commands in
-.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.
-.It Ic \&: Op Ar ...
-The null command.
-Exit status is set to zero.
-.It Xo Ic alias
-.Op Fl d | Ic +-t Op Fl r
-.Op Ic +-px
-.Op Ic +-
-.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.
-In addition, if the
-.Fl p
-option is used, each alias is prefixed with the string
-.Dq alias\ \& .
-.Pp
-The
-.Fl x
-option sets
-.Po Ic \&+x
-\ clears
-.Pc
-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
-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
-.Fl d
-option causes directory aliases, which are used in tilde expansion, to be
-listed or set (see
-.Sx Tilde expansion
-above).
-.It Ic bg Op Ar job ...
-Resume the specified stopped job(s) in the background.
-If no jobs are specified,
-.Ic %\&+
-is assumed.
-This command is only available on systems which support job control (see
-.Sx Job control
-below for more information).
-.It Ic bind Op Fl l
-The current bindings are listed.
-If the
-.Fl l
-flag is given,
-.Ic bind
-instead lists the names of the functions to which keys may be bound.
-See
-.Sx Emacs editing mode
-for more information.
-.It Xo Ic bind Op Fl m
-.Ar string Ns = Ns Op Ar substitute
-.Ar ...
-.Xc
-.It Xo Ic bind
-.Ar string Ns = Ns Op Ar editing-command
-.Ar ...
-.Xc
-The specified editing command is bound to the given
-.Ar string ,
-which should consist of a control character (which may be written using caret
-notation, i.e., ^X), optionally preceded by one of the two prefix characters.
-If the
-.Fl m
-flag is given, the specified input
-.Ar string
-will afterwards be immediately replaced by the given
-.Ar substitute
-string, which may contain editing commands.
-.Pp
-Future input of the
-.Ar string
-will cause the editing command to be immediately invoked.
-Note that although only two prefix characters (usually
-.Tn ESC
-and ^X) are supported, some
-multi-character sequences can be supported.
-The following binds the arrow keys on an
-.Tn ANSI
-terminal, or
-.Xr xterm 1
-(these are in the default bindings).
-Of course some escape sequences won't work out quite this nicely.
-.Pp
-.Bl -item -compact
-.It
-.Ic bind '^[['=prefix-2
-.It
-.Ic bind '^XA'=up-history
-.It
-.Ic bind '^XB'=down-history
-.It
-.Ic bind '^XC'=forward-char
-.It
-.Ic bind '^XD'=backward-char
-.El
-.It Ic break Op Ar level
-Exit the
-.Ar level Ns th
-inner-most
-.Ic for ,
-.Ic select ,
-.Ic until ,
-or
-.Ic while
-loop.
-.Ar level
-defaults to 1.
-.It Ic builtin Ar command Op Ar arg1 ...
-Execute the built-in command
-.Ar command .
-.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.
-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.
-If
-.Ar dir
-is missing, the home directory
-.Ev HOME
-is used.
-If
-.Ar dir
-is
-.Ql - ,
-the previous working directory is used (see
-.Ev OLDPWD
-parameter).
-If the
-.Fl L
-option (logical path) is used or if the
-.Ic physical
-option (see the
-.Ic set
-command below) isn't set, references to
-.Dq \&.\&.
-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,
-.Dq \&.\&.
-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.
-.It Xo 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.
-.It Xo Ic command Op Fl pvV
-.Ar cmd Op Ar arg1 ...
-.Xc
-If neither the
-.Fl v
-nor
-.Fl V
-option is given,
-.Ar cmd
-is executed exactly as if
-.Ic command
-had not been specified, with two exceptions.
-First,
-.Ar cmd
-cannot be a shell function, and second, 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).
-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
-.Tn POSIX Ns ish
-systems, it is the value returned by
-.Ic getconf CS_PATH ) .
-.Pp
-If the
-.Fl v
-option is given, instead of executing
-.Ar cmd ,
-information about what would be executed is given (and the same is done for
-.Ar arg1 ... ) .
-For special and regular built-in commands and functions, their names are simply
-printed; for aliases, a command that defines them is printed; and for commands
-found by searching the
-.Ev PATH
-parameter, the full path of the command is printed.
-If no command is found
-(i.e., the path search fails), nothing is printed and
-.Ic command
-exits with a non-zero status.
-The
-.Fl V
-option is like the
-.Fl v
-option, except it is more verbose.
-.It Ic continue Op Ar level
-Jumps to the beginning of the
-.Ar level Ns th
-inner-most
-.Ic for ,
-.Ic select ,
-.Ic until ,
-or
-.Ic while
-loop.
-.Ar level
-defaults to 1.
-.It Xo Ic echo Op Fl neE
-.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.
-.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.
-.It Xo 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 greater than 2 which are opened or
-.Xr dup 2 Ns 'd
-in this way are not made available to other executed commands (i.e., commands
-that are not built-in to the shell).
-Note that the Bourne shell differs here;
-it does pass these file descriptors on.
-.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.
-.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
-.Ic export
-commands defining all exported parameters, including their values, are printed.
-.It Ic false
-A command that exits with a non-zero status.
-.It Xo Ic fc
-.Oo Fl e Ar editor \*(Ba
-.Fl l Op Fl n Oc
-.Op Fl r
-.Op Ar first Op Ar last
-.Xc
-.Ar first
-and
-.Ar last
-select commands from the history.
-Commands can be selected by history number
-or a string specifying the most recent command starting with that string.
-The
-.Fl l
-option lists the command on stdout, and
-.Fl n
-inhibits the default command numbers.
-The
-.Fl r
-option reverses the order of the list.
-Without
-.Fl l ,
-the selected commands are edited by the editor specified with the
-.Fl e
-option, or if no
-.Fl e
-is specified, the editor specified by the
-.Ev FCEDIT
-parameter (if this parameter is not set,
-.Pa /bin/ed
-is used), and then executed by the shell.
-.It Xo Ic fc
-.Oo Fl e No \&- \&| Fl s Oc
-.Op Fl g
-.Op Ar old Ns = Ns Ar new
-.Op Ar prefix
-.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
-.Ar old
-are replaced with
-.Ar new .
-This command is usually accessed with the predefined
-.Ic alias r='fc -e -' .
-.It Ic fg Op Ar job ...
-Resume the specified job(s) in the foreground.
-If no jobs are specified,
-.Ic %\&+
-is assumed.
-This command is only available on systems which support job control (see
-.Sx Job control
-below for more information).
-.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
-.Ic getopts
-is invoked, it places the next option in the shell parameter
-.Ar name
-and the index of the next argument to be processed in the shell parameter
-.Ev OPTIND .
-If the option was introduced with a
-.Ql + ,
-the option placed in
-.Ar name
-is prefixed with a
-.Ql + .
-When an option requires an argument,
-.Ic getopts
-places it in the shell parameter
-.Ev OPTARG .
-When an illegal option or a missing option argument is encountered, a question
-mark or a colon is placed in
-.Ar name
-(indicating an illegal option or missing argument, respectively) and
-.Ev OPTARG
-is set to the option character that caused the problem.
-If
-.Ar optstring
-does not begin with a colon, a question mark is placed in
-.Ar name ,
-.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.
-.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.
-.It Xo Ic jobs Op Fl lpn
-.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.
-.It Xo Ic kill
-.Oo Fl s Ar signame \*(Ba
-.Fl Ar signum | Fl Ar signame Oc {
-.Ar job |
-.Ar pid |
-.Ar pgrp No } Ar ...
-.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 .
-.It Ic kill -l Op Ar exit-status ...
-Print the name of the signal that killed a process which exited with the
-specified
-.Ar exit-status Ns es.
-If no arguments are specified, a list of all the signals, their numbers and
-a short description of them are printed.
-.It Ic let Op Ar expression ...
-Each expression is evaluated (see
-.Sx Arithmetic expressions
-above).
-If all expressions are successfully evaluated, the exit status is 0 (1)
-if the last expression evaluated to non-zero (zero).
-If an error occurs during
-the parsing or evaluation of an expression, the exit status is greater than 1.
-Since expressions may need to be quoted,
-.Ic (( Ar expr Ic ))
-is syntactic sugar for
-.Ic let \&" Ns Ar expr Ns Ic \&" .
-.It Xo Ic print
-.Oo Fl nprsu Ns Ar n \*(Ba
-.Fl R Op Fl en Oc
-.Op Ar argument ...
-.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, the
-.Fl u
-option prints to file descriptor
-.Ar n
-.Po
-.Ar n
-defaults to 1 if omitted
-.Pc ,
-and the
-.Fl p
-option prints to the co-process (see
-.Sx Co-processes
-above).
-.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.
-.It Ic pwd Op Fl LP
-Print the present working directory.
-If the
-.Fl L
-option is used or if the
-.Ic physical
-option (see the
-.Ic set
-command below) isn't set, 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
-.Dq \&.\&.
-directories to the root directory) is printed.
-.It Xo Ic read Oo Fl prsu Ns Ar n
-.Oc 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.
-.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: ' ) .
-.Pp
-The
-.Fl u Ns Ar n
-and
-.Fl p
-options cause input to be read from file descriptor
-.Ar n
-or the current co-process (see
-.Sx Co-processes
-above for comments on this), respectively.
-If the
-.Fl s
-option is used, input is saved to the history file.
-.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.
-.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.
-.It Xo Ic set Op Ic +-abCefhkmnpsuvxX
-.Op Ic +-o Ar option
-.Op Ic +-A Ar name
-.Op Fl \&-
-.Op Ar arg ...
-.Xc
-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
-.Ic \&+ Ns Fl o Ar option
-syntax, where
-.Ar option
-is the long name of an option, or using the
-.Ic \&+\&- 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
-Sets the elements of the array parameter
-.Ar name
-to
-.Ar arg ... .
-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
-.Ar arg Ns s ) ,
-the rest are left untouched.
-.It Fl a Ic allexport
-All new parameters are created with the export attribute.
-.It Fl b Ic notify
-Print job notification messages asynchronously, instead of just before the
-prompt.
-Only used if job control is enabled
-.Pq Fl m .
-.It Ic csh-history
-Enables a subset of
-.Xr csh 1 Ns -style
-history editing using the
-.Ql !\&
-character.
-.It Fl C Ic noclobber
-Prevent
-.Ic \&>
-redirection from overwriting existing files
-.Po
-.Ic \&>\&|
-must be used to force an overwrite
-.Pc .
-.It Fl e 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 ,
-.Ic \&&\&& ,
-or
-.Ic \&|\&|
-statements.
-.It Fl f Ic noglob
-Do not expand file name patterns.
-.It Fl h Ic trackall
-Create tracked aliases for all executed commands (see
-.Sx Aliases
-above).
-Enabled by default for non-interactive shells.
-.It Fl i Ic interactive
-Enable interactive mode.
-This can only be set/unset when the shell is invoked.
-.It Fl k Ic keyword
-Parameter assignments are recognized anywhere in a command.
-.It Fl l Ic login
-The shell is a login shell.
-This can only be set/unset when the shell is invoked (see
-.Sx Shell startup
-above).
-.It Fl m Ic monitor
-Enable job control (default for interactive shells).
-.It Fl n Ic noexec
-Do not execute any commands.
-Useful for checking the syntax of scripts
-(ignored if interactive).
-.It Fl p Ic privileged
-Set automatically if, when the shell starts, the read UID or GID does not match
-the effective UID (EUID) or GID (EGID), respectively.
-See
-.Sx Shell startup
-above for a description of what this means.
-.It Fl r Ic restricted
-Enable restricted mode.
-This option can only be used when the shell is invoked.
-See
-.Sx Shell startup
-above for a description of what this means.
-.It Fl s Ic stdin
-If used where 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 ,
-if
-.Fl A
-is used).
-.It Fl u Ic nounset
-Referencing of an unset parameter is treated as an error, unless one of the
-.Ql - ,
-.Ql +
-or
-.Ql =
-modifiers is used.
-.It Fl v Ic verbose
-Write shell input to standard error as it is read.
-.It Fl x Ic xtrace
-Print commands and parameter assignments when they are executed, preceded by
-the value of
-.Ev PS4 .
-.It Fl X Ic markdirs
-Mark directories with a trailing
-.Ql /
-during file name generation.
-.It Ic bgnice
-Background jobs are run with lower priority.
-.It Ic braceexpand
-Enable brace expansion (a.k.a., alternation).
-.It Ic emacs
-Enable BRL emacs-like command-line editing (interactive shells only); see
-.Sx Emacs editing mode .
-.It Ic emacs-usemeta
-In emacs command-line editing, use the 8th bit as meta (^[) prefix.
-This is the default.
-.It Ic gmacs
-Enable gmacs-like command-line editing (interactive shells only).
-Currently identical to emacs editing except that transpose (^T) acts slightly
-differently.
-.It Ic ignoreeof
-The shell will not (easily) exit when end-of-file is read;
-.Ic exit
-must be used.
-To avoid infinite loops, the shell will exit if
-.Dv EOF
-is read 13 times in a row.
-.It Ic nohup
-Do not kill running jobs with a
-.Dv SIGHUP
-signal when a login shell exists.
-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)
-.Dq \&.\&.
-directories instead of
-.Dq logical
-directories (i.e., the shell handles
-.Dq \&.\&. ,
-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
-.Tn POSIX
-mode.
-See
-.Sx POSIX mode
-above.
-.It Ic sh
-Enable strict Bourne shell mode (see
-.Sx Strict Bourne shell mode ) .
-.It Ic vi
-Enable
-.Xr vi 1 Ns -like
-command-line editing (interactive shells only).
-.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
-.Tn ESC
-(^[) was entered.
-.Nm pdksh
-is always in viraw mode.
-.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
-.Dq 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.
-This is the default.
-.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
-.Dv \&- .
-.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.,
-.Ic $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 \(em it clears both the
-.Fl x
-and
-.Fl v
-options.
-.It Ic shift Op Ar number
-The positional parameters
-.Ar number Ns +1 ,
-.Ar number Ns +2 ,
-etc. are renamed to
-.Dq 1 ,
-.Dq 2 ,
-etc.
-.Ar number
-defaults to 1.
-.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
-and
-.Ic while
-statements.
-Symbolic links are followed for all
-.Ar file
-expressions except
-.Fl h
-and
-.Fl L .
-.Pp
-The following basic expressions are available:
-.Bl -tag -width 17n
-.It Fl r Ar file
-.Ar file
-exists and is readable.
-.It Fl w Ar file
-.Ar file
-exists and is writable.
-.It Fl x Ar file
-.Ar file
-exists and is executable.
-.It Fl a Ar file
-.Ar file
-exists.
-.It Fl e Ar file
-.Ar file
-exists.
-.It Fl f Ar file
-.Ar file
-is a regular file.
-.It Fl d Ar file
-.Ar file
-is a directory.
-.It Fl c Ar file
-.Ar file
-is a character special device.
-.It Fl b Ar file
-.Ar file
-is a block special device.
-.It Fl p Ar file
-.Ar file
-is a named pipe.
-.It Fl u Ar file
-.Ar file Ns 's
-mode has setuid bit set.
-.It Fl g Ar file
-.Ar file Ns 's
-mode has setgid bit set.
-.It Fl k Ar file
-.Ar file Ns 's
-mode has sticky bit set.
-.It Fl s Ar file
-.Ar file
-is not empty.
-.It Fl O Ar file
-.Ar file Ns 's
-owner is the shell's effective user ID.
-.It Fl G Ar file
-.Ar file Ns 's
-group is the shell's effective group ID.
-.It Fl h Ar file
-.Ar file
-is a symbolic link.
-.It Fl H Ar file
-.Ar file
-is a context dependent directory (only useful on HP-UX).
-.It Fl L Ar file
-.Ar file
-is a symbolic link.
-.It Fl S Ar file
-.Ar file
-is a socket.
-.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 (thus
-.Ic \&[ -o Ar foo
-.Ic -o -o \&! Ns Ar foo Ic \&]
-returns true if and only if option
-.Ar foo
-exists).
-.It Ar file1 Fl nt Ar file2
-.Ar file1
-is newer than
-.Ar file2
-or
-.Ar file1
-exists and
-.Ar file2
-does not.
-.It Ar file1 Fl ot Ar file2
-.Ar file1
-is older than
-.Ar file2
-or
-.Ar file2
-exists and
-.Ar file1
-does not.
-.It Ar file1 Fl ef Ar file2
-.Ar file1
-is the same file as
-.Ar file2 .
-.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
-.Tn POSIX
-rules described below).
-.It Ar string
-.Ar string
-has non-zero length.
-Note that there is the potential for problems if
-.Ar string
-turns out to be an operator (e.g.,
-.Fl r ) .
-It is generally better to use a test like
-.Sm off
-.Ic \&[\ X\&" Ar string Ic \&" Ic \ \&]
-.Sm on
-instead (double quotes are used in case
-.Ar string
-contains spaces or file globbing characters).
-.It Fl z Ar string
-.Ar string
-is empty.
-.It Fl n Ar string
-.Ar string
-is not empty.
-.It Ar string No = Ar string
-Strings are equal.
-.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 \&lt Ar number
-Numbers compare less than.
-.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):
-.Pp
-.Bl -tag -width "expr -o expr" -compact
-.It Ar expr Fl o Ar expr
-Logical
-.Tn OR .
-.It Ar expr Fl a Ar expr
-Logical
-.Tn AND .
-.It Ic \&! Ar expr
-Logical
-.Tn NOT .
-.It Ic \&( Ar expr Ic \&)
-Grouping.
-.El
-.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,
-.Ic \&[ -w /dev/fd/2 \&]
-tests if file descriptor 2 is writable.
-.Pp
-Note that some special rules are applied (courtesy of
-.Tn 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
-.Ic if \&[ $foo = bar \&]
-which fails if parameter
-.Ic foo
-is
-.Dv NULL
-or unset, if it has embedded spaces (i.e.,
-.Ev IFS
-characters), or if it is a unary operator like
-.Sq Ic \&!
-or
-.Sq Fl n .
-Use tests like
-.Ic if \&[ \&"X$foo\&" = Xbar \&]
-instead.
-.It Xo Ic time Op Fl p
-.Op Ar pipeline
-.Xc
-If a
-.Ar pipeline
-is given, the times used to execute the pipeline are reported.
-If no pipeline
-is given, then the user and system time used by the shell itself, and all the
-commands it has run since it was started, are reported.
-The times reported are the real time (elapsed time from start to finish),
-the user CPU time (time spent running in user mode), and the system CPU time
-(time spent running in kernel mode).
-Times are reported to standard error; the format of the output is:
-.Pp
-.Dl "0m0.00s real     0m0.00s user     0m0.00s system"
-.Pp
-If the
-.Fl p
-option is given the output is slightly longer:
-.Bd -literal -offset indent
-real     0.00
-user     0.00
-sys      0.00
-.Ed
-.Pp
-It is an error to specify the
-.Fl p
-option unless
-.Ar pipeline
-is a simple command.
-.Pp
-Simple redirections of standard error do not effect the output of the
-.Ic time
-command:
-.Pp
-.Dl time sleep 1 2> afile
-.Dl { time sleep 1; } 2> afile
-.Pp
-Times for the first command do not go to
-.Dq afile ,
-but those of the second command do.
-.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
-.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 Fl l
-command above).
-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 see \(em 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
-and
-.Dv EXIT
-traps in functions are not yet implemented.
-.It Ic true
-A command that exits with a zero value.
-.It Xo Ic typeset
-.Oo Op Ic +-Ulprtux
-.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 \&| Fl f Op Fl tux Oc
-.Oo 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.
-.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 Ns s
-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 3n
-.It Fl L Ns 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 R Ns 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 Z Ns 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.
-.It Fl i Ns 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 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 f
-Function mode.
-Display or set functions and their attributes, instead of parameters.
-.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
-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
-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.
-.El
-.It Xo Ic ulimit Op Fl acdfHlmnpsStv
-.Op Ar value
-.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 or the word
-.Dq unlimited .
-The limits affect the shell and any processes created by the shell after a
-limit is imposed.
-Note that some systems may not allow limits to be increased
-once they are set.
-Also note that the types of limits available are system
-dependent \(em some systems have only the
-.Fl f
-limit.
-.Bl -tag -width 5n
-.It Fl a
-Displays all limits; unless
-.Fl H
-is used, soft limits are displayed.
-.It Fl H
-Set the hard limit only (default is to set both hard and soft limits).
-.It Fl S
-Set the soft limit only (default is to set both hard and soft limits).
-.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 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 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
-.Tn CPU
-seconds 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
-.Pp
-As far as
-.Ic ulimit
-is concerned, a block is 512 bytes.
-.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 .
-.It Xo Ic unalias Op Fl adt
-.Op Ar name1 ...
-.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.
-.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 were already unset, zero
-otherwise.
-.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 ,
-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).
-.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 Fl m
-or
-.Ic set Fl o Ic 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.
-.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 10n
-.It Ic %\&+
-The most recently stopped job, or, if there are no stopped jobs, the oldest
-running job.
-.It Ic %% , %
-Same as
-.Ic %\&+ .
-.It Ic %\&-
-The job that would be the
-.Ic %\&+
-job if the latter did not exist.
-.It Ic % Ns Ar n
-The job with job number
-.Ar n .
-.It Ic %\&? Ns Ar string
-The job containing the string
-.Ar string
-(an error occurs if multiple jobs are matched).
-.It Ic % Ns Ar string
-The job starting with string
-.Ar string
-(an error occurs if multiple jobs are matched).
-.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:
-.Bd -unfilled -offset indent
-.Ic \&[ Ar number Ic \&] Ar flag status command
-.Ed
-.Pp
-where
-.Bl -tag -width "status"
-.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 %\&+ 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 "Running"
-.It Cm Running
-The job has neither stopped nor exited (note that running does not necessarily
-mean consuming
-.Tn CPU
-time \(em the process could be blocked waiting for some
-event).
-.It Cm 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 Cm 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, etc.; use
-.Ic kill -l
-for a list of signal descriptions).
-The
-.Dq core dumped
-message indicates the process created a core file.
-.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.
-.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.
-.Ss Interactive input line editing
-The shell supports three modes of reading command lines from a
-.Xr tty 4
-in an
-interactive session, which is controlled by the
-.Ic emacs ,
-.Ic gmacs ,
-and
-.Ic vi
-options (at most one of these can be set at once).
-If none of these options are enabled, the shell simply reads lines using the
-normal
-.Xr tty 4
-driver.
-If the
-.Ic emacs
-or
-.Ic gmacs
-option is set, the shell allows emacs-like editing of the command; similarly,
-if the
-.Ic vi
-option is set, the shell allows vi-like editing of the command.
-These modes are described in detail in the following sections.
-.Pp
-In these editing modes, if a line is longer than the screen width (see
-.Ev COLUMNS
-parameter),
-a
-.Ql > ,
-.Ql + ,
-or
-.Ql <
-character is displayed in the last column indicating that there are more
-characters after, before and after, or before the current position,
-respectively.
-The line is scrolled horizontally as necessary.
-.Ss Emacs editing mode
-When the
-.Ic emacs
-option is set, interactive input line editing is enabled.
-Warning: This mode is
-slightly different from the emacs mode in the original Korn shell.
-In this mode, various editing commands
-(typically bound to one or more control characters) cause immediate actions
-without waiting for a newline.
-Several editing commands are bound to particular
-control characters when the shell is invoked; these bindings can be changed
-using the
-.Ic bind
-command.
-.Pp
-The following is a list of available editing commands.
-Each description starts with the name of the command, an
-.Ar n
-(if the command can be prefixed with a count), and any keys the command is
-bound to by default (written using caret notation, i.e.,
-.Tn "ASCII ESC"
-character is
-written as ^[).
-A count prefix for a command is entered using the sequence
-.Ic ^\&[ Ns Ar n ,
-where
-.Ar n
-is a sequence of 1 or more digits; unless otherwise specified, if a count is
-omitted, it defaults to 1.
-Note that editing command names are used only with the
-.Ic bind
-command.
-Furthermore, many editing commands are useful only on terminals with
-a visible cursor.
-The default bindings were chosen to resemble corresponding
-Emacs key bindings.
-The users'
-.Xr tty 4
-characters (e.g.,
-.Dv ERASE )
-are bound to
-reasonable substitutes and override the default bindings.
-.Bl -tag -width Ds
-.It Ic abort ^G
-Useful as a response to a request for a
-.Ic search-history
-pattern in order to abort the search.
-.It Ic auto-insert Ar n
-Simply causes the character to appear as literal input.
-Most ordinary characters are bound to this.
-.It Ic backward-char Ar n Ic ^B
-Moves the cursor backward
-.Ar n
-characters.
-.It Ic backward-word Ar n Ic ^[B
-Moves the cursor backward to the beginning of the word; words consist of
-alphanumerics, underscore
-.Pq Sq _
-and dollar sign
-.Pq Sq $
-characters.
-.It Ic beginning-of-history ^[<
-Moves to the beginning of the history.
-.It Ic beginning-of-line ^A
-Moves the cursor to the beginning of the edited input line.
-.It Ic capitalize-word Ar n Ic ^[c , ^[C
-Uppercase the first character in the next
-.Ar n
-words, leaving the cursor past the end of the last word.
-.It Ic comment ^[#
-If the current line does not begin with a comment character, one is added at
-the beginning of the line and the line is entered (as if return had been
-pressed); otherwise, the existing comment characters are removed and the cursor
-is placed at the beginning of the line.
-.It Ic complete ^[^[
-.It Ic complete ^I
-Automatically completes as much as is unique of the command name or the file
-name containing the cursor.
-If the entire remaining command or file name is
-unique, a space is printed after its completion, unless it is a directory name
-in which case
-.Ql /
-is appended.
-If there is no command or file name with the current partial word
-as its prefix, a bell character is output (usually causing a beep to be
-sounded).
-.It Ic complete-command ^X^[
-Automatically completes as much as is unique of the command name having the
-partial word up to the cursor as its prefix, as in the
-.Ic complete
-command above.
-.It Ic complete-file ^[^X
-Automatically completes as much as is unique of the file name having the
-partial word up to the cursor as its prefix, as in the
-.Ic complete
-command described above.
-.It Ic complete-list ^[=
-List the possible completions for the current word.
-.It Xo Ic delete-char-backward Ar n Ic ERASE ,
-.Ic ^? , ^H
-.Xc
-Deletes
-.Ar n
-characters before the cursor.
-.It Ic delete-char-forward Ar n
-Deletes
-.Ar n
-characters after the cursor.
-.It Xo Ic delete-word-backward Ar n Ic ^[ERASE ,
-.Ic ^[^? , ^[^H , ^[h
-.Xc
-Deletes
-.Ar n
-words before the cursor.
-.It Ic delete-word-forward Ar n Ic ^[d
-Deletes characters after the cursor up to the end of
-.Ar n
-words.
-.It Ic down-history Ar n Ic ^N
-Scrolls the history buffer forward
-.Ar n
-lines (later).
-Each input line originally starts just after the last entry
-in the history buffer, so
-.Ic down-history
-is not useful until either
-.Ic search-history
-or
-.Ic up-history
-has been performed.
-.It Ic downcase-word Ar n Ic ^[L , ^[l
-Lowercases the next
-.Ar n
-words.
-.It Ic end-of-history ^[>
-Moves to the end of the history.
-.It Ic end-of-line ^E
-Moves the cursor to the end of the input line.
-.It Ic eot ^_
-Acts as an end-of-file; this is useful because edit-mode input disables
-normal terminal input canonicalization.
-.It Ic eot-or-delete Ar n Ic ^D
-Acts as
-.Ic eot
-if alone on a line; otherwise acts as
-.Ic delete-char-forward .
-.It Ic error
-Error (ring the bell).
-.It Ic exchange-point-and-mark ^X^X
-Places the cursor where the mark is and sets the mark to where the cursor was.
-.It Ic expand-file ^[\&*
-Appends a
-.Ql *
-to the current word and replaces the word with the result of performing file
-globbing on the word.
-If no files match the pattern, the bell is rung.
-.It Ic forward-char Ar n Ic ^F
-Moves the cursor forward
-.Ar n
-characters.
-.It Ic forward-word Ar n Ic ^[f
-Moves the cursor forward to the end of the
-.Ar n Ns th
-word.
-.It Ic goto-history Ar n Ic ^[g
-Goes to history number
-.Ar n .
-.It Ic kill-line KILL
-Deletes the entire input line.
-.It Ic kill-region ^W
-Deletes the input between the cursor and the mark.
-.It Ic kill-to-eol Ar n Ic ^K
-Deletes the input from the cursor to the end of the line if
-.Ar n
-is not specified; otherwise deletes characters between the cursor and column
-.Ar n .
-.It Ic list ^[?
-Prints a sorted, columnated list of command named or file names (if any) that
-can complete the partial word containing the cursor.
-Directory names have
-.Ql /
-appended to them.
-.It Ic list-command ^X?
-Prints a sorted, columnated list of command names (if any) that can complete
-the partial word containing the cursor.
-.It Ic list-file ^X^Y
-Prints a sorted, columnated list of file names (if any) that can complete the
-partial word containing the cursor.
-File type indicators are appended as described under
-.Ic list
-above.
-.It Ic newline ^J , ^M
-Causes the current input line to be processed by the shell.
-The current cursor position may be anywhere on the line.
-.It Ic newline-and-next ^O
-Causes the current input line to be processed by the shell, and the next line
-from history becomes the current line.
-This is only useful after an
-.Ic up-history
-or
-.Ic search-history .
-.It Ic no-op QUIT
-This does nothing.
-.It Ic prefix-1 ^[
-Introduces a 2-character command sequence.
-.It Ic prefix-2 ^X
-.It Ic prefix-2 ^[[
-Introduces a 2-character command sequence.
-.It Ic prev-hist-word Ar n Ic ^[\&. , ^[_
-The last
-.Pq Ar n Ns th
-word of the previous command is inserted at the cursor.
-.It Ic quote ^^
-The following character is taken literally rather than as an editing command.
-.It Ic redraw ^L
-Reprints the prompt string and the current input line.
-.It Ic search-character-backward Ar n Ic ^[^]
-Search backward in the current line for the
-.Ar n Ns th
-occurrence of the next character typed.
-.It Ic search-character-forward Ar n Ic ^]
-Search forward in the current line for the
-.Ar n Ns th
-occurrence of the next character typed.
-.It Ic search-history ^R
-Enter incremental search mode.
-The internal history list is searched
-backwards for commands matching the input.
-An initial
-.Ql ^
-in the search string anchors the search.
-The abort key will leave search mode.
-Other commands will be executed after leaving search mode.
-Successive
-.Ic search-history
-commands continue searching backward to the next previous occurrence of the
-pattern.
-The history buffer retains only a finite number of lines; the oldest
-are discarded as necessary.
-.It Ic set-mark-command ^[ Ns <space>
-Set the mark at the cursor position.
-.It Ic stuff
-On systems supporting it, pushes the bound character back onto the terminal
-input where it may receive special processing by the terminal handler.
-This is useful for the BRL ^T mini-systat feature, for example.
-.It Ic stuff-reset
-Acts like
-.Ic stuff ,
-then aborts input the same as an interrupt.
-.It Ic transpose-chars ^T
-If at the end of line, or if the
-.Ic gmacs
-option is set, this exchanges the two previous characters; otherwise, it
-exchanges the previous and current characters and moves the cursor one
-character to the right.
-.It Ic up-history Ar n Ic ^P
-Scrolls the history buffer backward
-.Ar n
-lines (earlier).
-.It Ic upcase-word Ar n Ic ^[U , ^[u
-Uppercase the next
-.Ar n
-words.
-.It Ic version ^V
-Display the version of
-.Nm .
-The current edit buffer is restored as soon as any
-key is pressed (the key is then processed, unless it is a space).
-.It Ic yank ^Y
-Inserts the most recently killed text string at the current cursor position.
-.It Ic yank-pop ^[y
-Immediately after a
-.Ic yank ,
-replaces the inserted text string with the next previously killed text string.
-.El
-.Ss Vi editing mode
-The vi command-line editor in
-.Nm
-has basically the same commands as the vi
-editor (see
-.Xr vi 1 ) ,
-with the following exceptions:
-.Bl -bullet
-.It
-You start out in insert mode.
-.It
-There are file name and command completion commands
-.Po
-.Ic = , \e , \&* , ^X ,
-.Ic ^E , ^F ,
-and, optionally,
-.Ic <tab>
-.Pc .
-.It
-The
-.Ic _
-command is different (in
-.Nm
-it is the last argument command, in vi it goes to
-the start of the current line).
-.It
-The
-.Ic /
-and
-.Ic G
-commands move in the opposite direction as the
-.Ic j
-command.
-.It
-Commands which don't make sense in a single line editor are not available
-(e.g., screen movement commands,
-.Xr ex 1 Ns -style
-colon
-.Pq Ic \&:
-commands, etc.).
-.El
-.Pp
-Note that the ^X stands for control-X; also <esc>, <space> and <tab> are used
-for escape, space, and tab, respectively (no kidding).
-.Pp
-Like vi, there are two modes \(em
-.Dq insert
-mode and
-.Dq command
-mode.
-In insert mode, most characters are simply put in the buffer at the
-current cursor position as they are typed; however, some characters are
-treated specially.
-In particular, the following characters are taken from
-current tty settings (see
-.Xr tty 1 )
-and have their usual meaning (normal values are in parentheses): kill (^U),
-erase (^?), werase (^W), eof (^D), intr (^C), and quit (^\e).
-In addition to
-the above, the following characters are also treated specially in insert mode:
-.Bl -tag -width 10n
-.It Ic ^H
-Erases previous character.
-.It Ic ^V
-Literal next.
-The next character typed is not treated specially (can be used
-to insert the characters being described here).
-.It Ic ^J ^M
-End of line.
-The current line is read, parsed, and executed by the shell.
-.It Ic <esc>
-Puts the editor in command mode (see below).
-.It Ic ^E
-Command and file name enumeration (see below).
-.It Ic ^F
-Command and file name completion (see below).
-If used twice in a row, the
-list of possible completions is displayed; if used a third time, the completion
-is undone.
-.It Ic ^X
-Command and file name expansion (see below).
-.It Ic <tab>
-Optional file name and command completion (see
-.Ic ^F
-above), enabled with
-.Ic set Fl o Ic vi-tabcomplete .
-.El
-.Pp
-In command mode, each character is interpreted as a command.
-Characters that
-don't correspond to commands, are illegal combinations of commands, or are
-commands that can't be carried out all cause beeps.
-In the following command descriptions, an
-.Ar n
-indicates the command may be prefixed by a number (e.g.,
-.Ic 10l
-moves right 10 characters); if no number prefix is used,
-.Ar n
-is assumed to be 1 unless otherwise specified.
-The term
-.Dq current position
-refers to the position between the cursor and the character preceding the
-cursor.
-A
-.Dq word
-is a sequence of letters, digits, and underscore characters or a sequence of
-non-letter, non-digit, non-underscore, non-whitespace characters (e.g.,
-.Dq ab2\&*\&&^
-contains two words) and a
-.Dq big-word
-is a sequence of non-whitespace characters.
-.Pp
-Special
-.Nm
-vi commands
-.Pp
-The following commands are not in, or are different from, the normal vi file
-editor:
-.Bl -tag -width 10n
-.It Ar n Ns _
-Insert a space followed by the
-.Ar n Ns th
-big-word from the last command in the history at the current position and enter
-insert mode; if
-.Ar n
-is not specified, the last word is inserted.
-.It Ic \&#
-Insert the comment character
-.Pq Sq #
-at the start of the current line and return the line to the shell (equivalent
-to
-.Ic \&I#^J ) .
-.It Ar n Ns Ic g
-Like
-.Ic G ,
-except if
-.Ar n
-is not specified, it goes to the most recent remembered line.
-.It Ar n Ns Ic v
-Edit line
-.Ar n
-using the vi editor; if
-.Ar n
-is not specified, the current line is edited.
-The actual command executed is
-.Ic fc Fl e Ic ${VISUAL;-${EDITOR:-vi}} Ar n .
-.It Ic \&* No and Ic ^X
-Command or file name expansion is applied to the current big-word (with an
-appended
-.Ql * ,
-if the word contains no file globbing characters) \(em the big-word is replaced
-with the resulting words.
-If the current big-word is the first on the line (or
-follows one of the following characters:
-.Ql \&; ,
-.Ql | ,
-.Ql & ,
-.Ql ( ,
-or
-.Ql \&) )
-and does not contain a slash
-.Pq Sq /
-then the command expansion is done; otherwise file name expansion is done.
-Command expansion will match the big-word against all aliases, functions and
-built-in commands as well as any executable files found by searching the
-directories in the
-.Ev PATH
-parameter.
-File name expansion matches the big-word against the files in the
-current directory.
-After expansion, the cursor is placed just past the last
-word and the editor is in insert mode.
-.It Xo
-.Ar n Ns Ic \e Ns ,
-.Ar n Ns Ic ^F ,
-.Ar n Ns Ic <tab> ,
-.No and
-.Ar n Ns Ic <esc>
-.Xc
-Command/file name completion.
-Replace the current big-word with the
-longest unique match obtained after performing command and file name expansion.
-.Ic <tab>
-is only recognized if the
-.Ic vi-tabcomplete
-option is set, while
-.Ic <esc>
-is only recognized if the
-.Ic vi-esccomplete
-option is set (see
-.Ic set Fl o ) .
-If
-.Ar n
-is specified, the
-.Ar n Ns th
-possible completion is selected (as reported by the command/file name
-enumeration command).
-.It Ic \&= No and Ic ^E
-Command/file name enumeration.
-List all the commands or files that match the current big-word.
-.It Ic ^V
-Display the version of
-.Nm pdksh ;
-it is displayed until another key is pressed (this key is ignored).
-.It Ic @ Ns Ar c
-Macro expansion.
-Execute the commands found in the alias
-.Ar c .
-.El
-.Pp
-Intra-line movement commands:
-.Bl -tag -width Ds
-.It Xo Ar n Ns Ic h No and
-.Ar n Ns Ic ^H
-.Xc
-Move left
-.Ar n
-characters.
-.It Xo Ar n Ns Ic l No and
-.Ar n Ns Ic <space>
-.Xc
-Move right
-.Ar n
-characters.
-.It Ic \&0
-Move to column 0.
-.It Ic ^
-Move to the first non-whitespace character.
-.It Ar n Ns Ic \&|
-Move to column
-.Ar n .
-.It Ic $
-Move to the last character.
-.It Ar n Ns Ic b
-Move back
-.Ar n
-words.
-.It Ar n Ns Ic B
-Move back
-.Ar n
-big-words.
-.It Ar n Ns Ic e
-Move forward to the end of the word,
-.Ar n
-times.
-.It Ar n Ns Ic E
-Move forward to the end of the big-word,
-.Ar n
-times.
-.It Ar n Ns Ic w
-Move forward
-.Ar n
-words.
-.It Ar n Ns Ic W
-Move forward
-.Ar n
-big-words.
-.It Ic %
-Find match.
-The editor looks forward for the nearest parenthesis, bracket, or
-brace and then moves the cursor to the matching parenthesis, bracket, or brace.
-.It Ar n Ns Ic f Ns Ar c
-Move forward to the
-.Ar n Ns th
-occurrence of the character
-.Ar c .
-.It Ar n Ns Ic F Ns Ar c
-Move backward to the
-.Ar n Ns th
-occurrence of the character
-.Ar c .
-.It Ar n Ns Ic t Ns Ar c
-Move forward to just before the
-.Ar n Ns th
-occurrence of the character
-.Ar c .
-.It Ar n Ns Ic T Ns Ar c
-Move backward to just before the
-.Ar n Ns th
-occurrence of the character
-.Ar c .
-.It Ar n Ns Ic \&;
-Repeats the last
-.Ic f , F , t ,
-or
-.Ic T
-command.
-.It Ar n Ns Ic \&,
-Repeats the last
-.Ic f , F , t ,
-or
-.Ic T
-command, but moves in the opposite direction.
-.El
-.Pp
-Inter-line movement commands:
-.Bl -tag -width Ds
-.It Xo
-.Ar n Ns Ic j ,
-.Ar n Ns Ic + ,
-.No and
-.Ar n Ns Ic ^N
-.Xc
-Move to the
-.Ar n Ns th
-next line in the history.
-.It Xo
-.Ar n Ns Ic k ,
-.Ar n Ns Ic - ,
-.No and
-.Ar n Ns Ic ^P
-.Xc
-Move to the
-.Ar n Ns th
-previous line in the history.
-.It Ar n Ns Ic G
-Move to line
-.Ar n
-in the history; if
-.Ar n
-is not specified, the number of the first remembered line is used.
-.It Ar n Ns Ic g
-Like
-.Ic G ,
-except if
-.Ar n
-is not specified, it goes to the most recent remembered line.
-.It Ar n Ns Ic / Ns Ar string
-Search backward through the history for the
-.Ar n Ns th
-line containing
-.Ar string ;
-if
-.Ar string
-starts with
-.Ql ^ ,
-the remainder of the string must appear at the start of the history line for
-it to match.
-.It Ar n Ns Ic \&? Ns Ar string
-Same as
-.Ic / ,
-except it searches forward through the history.
-.It Ar n Ns Ic n
-Search for the
-.Ar n Ns th
-occurrence of the last search string; the directory of the search is the same
-as the last search.
-.It Ar n Ns Ic N
-Search for the
-.Ar n Ns th
-occurrence of the last search string; the directory of the search is the
-opposite of the last search.
-.El
-.Pp
-Edit commands
-.Bl -tag -width Ds
-.It Ar n Ns Ic a
-Append text
-.Ar n
-times; goes into insert mode just after the current position.
-The append is
-only replicated if command mode is re-entered (i.e., <esc> is used).
-.It Ar n Ns Ic A
-Same as
-.Ic a ,
-except it appends at the end of the line.
-.It Ar n Ns Ic i
-Insert text
-.Ar n
-times; goes into insert mode at the current position.
-The insertion is only
-replicated if command mode is re-entered (i.e., <esc> is used).
-.It Ar n Ns Ic I
-Same as
-.Ic i ,
-except the insertion is done just before the first non-blank character.
-.It Ar n Ns Ic s
-Substitute the next
-.Ar n
-characters (i.e., delete the characters and go into insert mode).
-.It Ic S
-Substitute whole line.
-All characters from the first non-blank character to the
-end of the line are deleted and insert mode is entered.
-.It Ar n Ns Ic c Ns Ar move-cmd
-Change from the current position to the position resulting from
-.Ar n move-cmd Ns s
-(i.e., delete the indicated region and go into insert mode); if
-.Ar move-cmd
-is
-.Ic c ,
-the line starting from the first non-blank character is changed.
-.It Ic C
-Change from the current position to the end of the line (i.e., delete to the
-end of the line and go into insert mode).
-.It Ar n Ns Ic x
-Delete the next
-.Ar n
-characters.
-.It Ar n Ns Ic X
-Delete the previous
-.Ar n
-characters.
-.It Ic D
-Delete to the end of the line.
-.It Ar n Ns Ic d Ns Ar move-cmd
-Delete from the current position to the position resulting from
-.Ar n move-cmd Ns s ;
-.Ar move-cmd
-is a movement command (see above) or
-.Ic d ,
-in which case the current line is deleted.
-.It Ar n Ns Ic r Ns Ar c
-Replace the next
-.Ar n
-characters with the character
-.Ar c .
-.It Ar n Ns Ic R
-Replace.
-Enter insert mode but overwrite existing characters instead of
-inserting before existing characters.
-The replacement is repeated
-.Ar n
-times.
-.It Ar n Ns Ic \&~
-Change the case of the next
-.Ar n
-characters.
-.It Ar n Ns Ic y Ns Ar move-cmd
-Yank from the current position to the position resulting from
-.Ar n move-cmd Ns s
-into the yank buffer; if
-.Ar move-cmd
-is
-.Ic y ,
-the whole line is yanked.
-.It Ic Y
-Yank from the current position to the end of the line.
-.It Ar n Ns Ic p
-Paste the contents of the yank buffer just after the current position,
-.Ar n
-times.
-.It Ar n Ns Ic P
-Same as
-.Ic p ,
-except the buffer is pasted at the current position.
-.El
-.Pp
-Miscellaneous vi commands
-.Bl -tag -width Ds
-.It Ic ^J No and Ic ^M
-The current line is read, parsed, and executed by the shell.
-.It Ic ^L No and Ic ^R
-Redraw the current line.
-.It Ar n Ns Ic \&.
-Redo the last edit command
-.Ar n
-times.
-.It Ic u
-Undo the last edit command.
-.It Ic U
-Undo all changes that have been made to the current line.
-.It Ar intr No and Ar quit
-The interrupt and quit terminal characters cause the current line to be
-deleted and a new prompt to be printed.
-.El
-.Sh FILES
-.Bl -tag -width "/etc/suid_profile" -compact
-.It Pa ~/.profile
-.It Pa /etc/profile
-.It Pa /etc/suid_profile
-.El
-.Sh SEE ALSO
-.Xr awk 1 ,
-.Xr csh 1 ,
-.Xr ed 1 ,
-.Xr getconf 1 ,
-.Xr getopt 1 ,
-.Xr sed 1 ,
-.Xr sh 1 ,
-.Xr stty 1 ,
-.Xr vi 1 ,
-.Xr dup 2 ,
-.Xr execve 2 ,
-.Xr getgid 2 ,
-.Xr getuid 2 ,
-.Xr open 2 ,
-.Xr pipe 2 ,
-.Xr wait 2 ,
-.Xr getopt 3 ,
-.Xr rand 3 ,
-.Xr signal 3 ,
-.Xr strftime 3 ,
-.Xr system 3 ,
-.Xr tty 4 ,
-.Xr environ 7
-.Pp
-.Rs
-.%A Morris Bolsky
-.%A David Korn
-.%T "The KornShell Command and Programming Language"
-.%D 1983
-.%O "ISBN 0-13-516972-0"
-.Re
-.Rs
-.%A Stephen G. Kochan
-.%A Patrick H. Wood
-.%T "UNIX Shell Programming"
-.%O "Hayden"
-.Re
-.Rs
-.%A "IEEE Inc."
-.%T "IEEE Standard for Information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities"
-.%D 1993
-.%O "ISBN 1-55937-266-9"
-.Re
-.Sh VERSION
-This page documents version @(#)PD KSH v5.2.14 99/07/13.2 of the public
-domain Korn shell.
-.Sh AUTHORS
-This shell is based on the public domain 7th edition Bourne shell clone by
-Charles Forsyth and parts of the BRL shell by Doug A. Gwyn, Doug Kingston,
-Ron Natalie, Arnold Robbins, Lou Salkind, and others.
-The first release of
-.Nm pdksh
-was created by Eric Gisin, and it was subsequently maintained by John R.\&
-MacMillan (change!john@sq.sq.com) and Simon J. Gerraty (sjg@zen.void.oz.au).
-The current maintainer is Michael Rendell (michael@cs.mun.ca).
-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.