KSH93(1) User Commands KSH93(1)

NAME

ksh93, rksh93 - Korn Shell, a standard and restricted command and
programming language

SYNOPSIS

ksh93 [+-abcefhikmnoprstuvxBCD] [-R file] [+-o option] ... [-] [arg ...]
rksh93 [+-abcefhikmnoprstuvxBCD] [-R file] [+-o option] ... [-] [arg ...]

DESCRIPTION

ksh93 is a command and programming language that executes commands read
from a terminal or a file. rksh93 is a restricted version of the command
interpreter ksh93. rksh93 is used to set up login names and execution
environments whose capabilities are more controlled than those of the
standard shell.

See Invocation for the meaning of arguments to the shell.

Definitions

A metacharacter is defined as one of the following characters:

; & ( ) | < > NEWLINE SPACE TAB

A blank is a TAB or a SPACE.

An identifier is a sequence of letters, digits, or underscores starting
with a letter or underscore. Identifiers are used as components of
variable names.

A vname is a sequence of one or more identifiers separated by a period (.)
and optionally preceded by a period (.). vnames are used as function and
variable names.

A word is a sequence of characters from the character set defined by the
current locale, excluding non-quoted metacharacters.

A command is a sequence of characters in the syntax of the shell language.
The shell reads each command and carries out the desired action either
directly or by invoking separate utilities. A built-in command is a
command that is carried out by the shell itself without creating a separate
process. Some commands are built-in purely for convenience and are not
documented in this manual page. Built-ins that cause side effects in the
shell environment and built-ins that are found before performing a path
search (see Execution) are documented in this manual page. For historical
reasons, some of these built-ins behave differently than other built-ins
and are called special built-ins.

Commands

A simple-command is a list of variable assignments (see Variable
Assignments) or a sequence of blank-separated words which can be preceded
by a list of variable assignments. See the Environment section of this
manual page.

The first word specifies the name of the command to be executed. Except as
specified in this section, the remaining words are passed as arguments to
the invoked command. The command name is passed as argument 0. See
exec(2). The value of a simple-command is its exit status. If it
terminates normally, its value is between 0 and 255. If it terminates
abnormally, its value is 256 + signum. The name of the signal
corresponding to the exit status can be obtained by way of the -l option of
the kill built-in utility.

A pipeline is a sequence of one or more commands separated by |. The
standard output of each command but the last is connected by a pipe(2) to
the standard input of the next command. Each command, except possibly the
last, is run as a separate process. The shell waits for the last command
to terminate. The exit status of a pipeline is the exit status of the last
command unless the pipefail option is enabled. Each pipeline can be
preceded by the reserved word !. This causes the exit status of the
pipeline to become 0 if the exit status of the last command is non-zero,
and 1 if the exit status of the last command is 0.

A list is a sequence of one or more pipelines separated by ;, &, |&, &&, or
|, and optionally terminated by ;, &, or |&. Of these five symbols, ;, &,
and |& have equal precedence, which is lower than that of && and ||. The
symbols && and || have equal precedence.

A semicolon (;) causes sequential execution of the preceding pipeline. An
ampersand (&) causes asynchronous execution of the preceding pipeline, that
is, the shell does not wait for that pipeline to finish. The symbol |&
causes asynchronous execution of the preceding pipeline with a two-way pipe
established to the parent shell. The standard input and output of the
spawned pipeline can be written to and read from by the parent shell by
applying the redirection operators <& and >& with arg p to commands and by
using -p option of the built-in commands read and print. The symbol &&
(||) causes the list following it to be executed only if the preceding
pipeline returns a zero (non-zero) value. One or more NEWLINEs can appear
in a list instead of a semicolon, to delimit a command. The first item of
the first pipeline of a list that is a simple command not beginning with a
redirection, and not occurring within a while, until, or if list, can be
preceded by a semicolon. This semicolon is ignored unless the showme
option is enabled as described with the set built-in.

A command is either a simple-command or one of commands in the following
list. Unless otherwise stated, the value returned by a command is that of
the last simple-command executed in the command.

for vname [in word ...] ;do list ;done

Each time a for command is executed, vname is set to the next word
taken from the in word list. If in word ... is omitted, the for
command executes the do list once for each positional parameter
that is set starting from 1. Execution ends when there are no more
words in the list. See Parameter Expansion.

for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done

The arithmetic expression expr1 is evaluated first. The arithmetic
expression expr2 is repeatedly evaluated until it evaluates to zero
and when non-zero, list is executed and the arithmetic expression
expr3 is evaluated. If any expression is omitted, then it behaves
as if it evaluated to 1. See Arithmetic Evaluation.

select vname [in word ...] ;do list ;done

A select command prints on standard error (file descriptor 2) the
set of words, each preceded by a number. If in word ... is
omitted, the positional parameters starting from 1 are used
instead. See Parameter Expansion. The PS3 prompt is printed and a
line is read from the standard input. If this line consists of the
number of one of the listed words, then the value of the variable
vname is set to the word corresponding to this number. If this
line is empty, the selection list is printed again. Otherwise the
value of the variable vname is set to NULL. The contents of the
line read from standard input is saved in the variable REPLY. The
list is executed for each selection until a break or EOF is
encountered. If the REPLY variable is set to NULL by the execution
of list, the selection list is printed before displaying the PS3
prompt for the next selection.

case word in [ [(] pattern [| pattern] ... ) list ;;] ... esac

A case command executes the list associated with the first pattern
that matches word. The form of the patterns is the same as that
used for file name generation. See File Name Generation.

The ;; operator causes execution of case to terminate. If ;& is
used in place of ;; the next subsequent list, if any, is executed.

if list ;then list [;elif list ;then list] ... [;else list] ;fi

The list following if is executed and, if it returns a zero exit
status, the list following the first then is executed. Otherwise,
the list following elif is executed, and, if its value is zero, the
list following the next then is executed. Failing each successive
elif list, the else list is executed. If the if list has non-zero
exit status and there is no else list, then the if command returns
a zero exit status.

while list ;do list ;done
until list ;do list ;done

A while command repeatedly executes the while list and, if the exit
status of the last command in the list is zero, executes the do
list, otherwise the loop terminates. If no commands in the do list
are executed, then the while command returns a zero exit status.
until can be used in place of while to negate the loop termination
test.

((expression))

The expression is evaluated using the rules for arithmetic
evaluation described in this manual page. If the value of the
arithmetic expression is non-zero, the exit status is 0. Otherwise
the exit status is 1.

(list)

Execute list in a separate environment. If two adjacent open
parentheses are needed for nesting, a SPACE must be inserted to
avoid evaluation as an arithmetic command as described in this
section.

{ list;}

list is simply executed. Unlike the metacharacters, ( and ), { and
} are reserved words and must occur at the beginning of a line or
after a ; to be recognized.

[[ expression ]]

Evaluates expression and returns a zero exit status when expression
is true. See Conditional Expressions for a description of
expression.

function varname { list ;}
varname () { list ;}

Define a function which is referenced by varname. A function whose
varname contains a dot (.) is called a discipline function and the
portion of the varname preceding the last . must refer to an
existing variable.

The body of the function is the list of commands between { and }.
A function defined with the function varname syntax can also be
used as an argument to the . special built-in command to get the
equivalent behavior as if the varname () syntax were used to define
it. See Functions.

namespace identifier { list };

Defines or uses the name space identifier and runs the commands in
list in this name space. See Name Spaces.

time [pipeline]

If pipeline is omitted, the user and system time for the current
shell and completed child processes is printed on standard error.
Otherwise, pipeline is executed and the elapsed time as well as the
user and system time are printed on standard error. The TIMEFORMAT
variable can be set to a format string that specifies how the
timing information should be displayed. See Shell Variables for a
description of the TIMEFORMAT variable.

The following reserved words are recognized as reserved only when they are
the first word of a command and are not quoted:

case do done else
elif esac for fi
function if select then
time until while { }
[[ ]] !

Variable Assignments

One or more variable assignments can start a simple command or can be
arguments to the typeset, enum, export, or readonly special built-in
commands. The syntax for an assignment is of the form:

varname=word
varname[word]=word

No space is permitted between varname and the = or between = and
word. The variable varname is unset before the assignment.

varname=(assignlist)

No space is permitted between varname and the =. An assignlist can
be one of the following:

word ...

Indexed array assignment.

[word]=word ...

Associative array assignment. If prefixed by typeset -a,
creates an indexed array instead.

assignment ...

Compound variable assignment. This creates a compound
variable varname with sub-variables of the form
varname.name, where name is the name portion of assignment.
The value of varname contains all the assignment elements.
Additional assignments made to sub-variables of varname are
also displayed as part of the value of varname. If no
assignments are specified, varname is a compound variable
allowing subsequence child elements to be defined.

typeset [options] assignment ...

Nested variable assignment. Multiple assignments can be
specified by separating each of them with a ;. The
previous value is unset before the assignment.

. filename

Include the assignment commands contained in filename.

In addition, a += can be used in place of the = to signify adding
to or appending to the previous value. When += is applied to an
arithmetic type, word is evaluated as an arithmetic expression and
added to the current value. When applied to a string variable, the
value defined by word is appended to the value. For compound
assignments, the previous value is not unset and the new values are
appended to the current ones provided that the types are
compatible. The right hand side of a variable assignment undergoes
all the expansion listed below except word splitting, brace
expansion, and file name generation. When the left hand side is an
assignment is a compound variable and the right hand is the name of
a compound variable, the compound variable on the right will be
copied or appended to the compound variable on the left.

Comments

A word beginning with # causes that word and all the following characters
up to a NEWLINE to be commented, or ignored.

Aliasing

The first word of each command is replaced by the text of an alias if an
alias for this word has been defined. An alias name consists of any number
of characters excluding metacharacters, quoting characters, file expansion
characters, parameter expansion characters, command substitution
characters, the characters / and =. The replacement string can contain any
valid shell script including the metacharacters listed in the Commands
section. The first word of each command in the replaced text, other than
any that are in the process of being replaced, are tested for aliases. If
the last character of the alias value is a BLANK then the word following
the alias is also checked for alias substitution.

Aliases can be used to redefine built-in commands but cannot be used to
redefine the reserved words listed in the Commands section. Aliases can be
created and listed with the alias command and can be removed with the
unalias command.

Aliasing is performed when scripts are read, not while they are executed.
For an alias to take effect, the alias definition command has to be
executed before the command which references the alias is read. The
following aliases are compiled into the shell but can be unset or
redefined:

autoload='typeset -fu'
command='command '
compound='typeset -C'
fc=hist
float='typeset -lE'
functions='typeset -f'
hash='alias -t --'
history='hist -l'
integer='typeset -li'
nameref='typeset -n'
nohup='nohup '
r='hist -s'
redirect='command exec'
source='command .'
stop='kill -s STOP'
suspend='kill -s STOP $$'
times='{ { time;} 2>&1;}'
type='whence -v'

Tilde Substitution

After alias substitution is performed, each word is checked to see if it
begins with an unquoted tilde (~). For tilde substitution, word also
refers to the word portion of parameter expansion. See Parameter
Expansion.

If it does, the word up to a / is checked to see if it matches a user name
in the password database. If a match is found, the ~ and the matched login
name are replaced by the login directory of the matched user. If no match
is found, the original text is left unchanged. A ~ by itself, or in front
of a /, is replaced by $HOME. A ~ followed by a + or - is replaced by the
value of $PWD and $OLDPWD respectively.

In addition, when expanding a variable assignment, tilde substitution is
attempted when the value of the assignment begins with a ~, and when a ~
appears after a colon (:). The : also terminates a ~ login name.

Command Substitution

The standard output from a command enclosed in parentheses preceded by a
dollar sign - $(list) - or in a brace group preceded by a dollar sign - ${
list;}, - or in a pair of grave accents - `` - can be used as part or all
of a word. Trailing NEWLINEs are removed. In the second case, the { and }
are treated as a reserved words so that { must be followed by a blank and }
must appear at the beginning of the line or follow a ;. In the third
(obsolete) form, the string between the quotes is processed for special
quoting characters before the command is executed. See Quoting.

The command substitution $(cat file) can be replaced by the equivalent but
faster $(<file). The command substitution $(n <#) expands to the current
byte offset for file descriptor n. Except for the second form, the command
list is run in a subshell so that no side effects are possible. For the
second form, the final } will be recognized as a reserved word after any
token.

Arithmetic Substitution

An arithmetic expression enclosed in double parentheses preceded by a
dollar sign - $((arithmetic_expression)) - is replaced by the value of the
arithmetic expression within the double parentheses.

Process Substitution

Each command argument of the form <(list) or >(list) runs process list
asynchronously connected to some file in /dev/fd. The name of this file
becomes the argument to the command. If the form with > is selected then
writing on this file provides input for list. If < is used, then the file
passed as an argument contains the output of the list process.

For example,

paste <(cut -f1 file1) <(cut -f3 file2) | tee \
>(process1) >(process2)

cuts fields 1 and 3 from the files file1 and file2 respectively, pastes the
results together, and sends it to the processes process1 and process2. It
also displays the results to the standard output. The file, which is
passed as an argument to the command, is a UNIX pipe(2). Programs that
expect to lseek(2) on the file do not work.

Process substitution of the form <(list) can also be used with the <
redirection operator which causes the output of list to be standard input
or the input for whatever file descriptor is specified.

Parameter Expansion

A parameter is a variable, one or more digits, or any of the characters *,
@, #, ?, -, $, and !. A variable is denoted by a vname. To create a
variable whose vname contains a ., a variable whose vname consists of
everything before the last . must already exist. A variable has a value
and zero or more attributes. Variables can be assigned values and
attributes by using the typeset special built-in command. The attributes
supported by the shell are described later with the typeset special built-
in command. Exported variables pass values and attributes to the
environment.

The shell supports both indexed and associative arrays. An element of an
array variable is referenced by a subscript. A subscript for an indexed
array is denoted by an arithmetic expression, (see Arithmetic Evaluation),
between a [ and a ]. To assign values to an indexed array, use
vname=(value ...) or set -A vname value .... The value of all subscripts
must be in the range of 0 to 4,194,303. A negative subscript is treated as
an offset from the maximum current index +1 so that -1 refers to the last
element. Indexed arrays can be declared with the -a option to typeset.
Indexed arrays need not be declared. Any reference to a variable with a
valid subscript is legal and an array will be created if necessary.

An associative array is created with the -A option to typeset. A subscript
for an associative array is denoted by a string enclosed between [ and ].

Referencing any array without a subscript is equivalent to referencing the
array with subscript 0.

The value of a variable can be assigned by:

vname=value [vname=value] ...

or

vname[subscript]=value [vname[subscript]=value] ...

Note that no space is allowed before or after the =.

Attributes assigned by the typeset special built-in command apply to all
elements of the array. An array element can be a simple variable, a
compound variable or an array variable. An element of an indexed array can
be either an indexed array or an associative array. An element of an
associative array can also be either. To refer to an array element that is
part of an array element, concatenate the subscript in brackets. For
example, to refer to the foobar element of an associative array that is
defined as the third element of the indexed array, use ${vname[3][foobar]}.

A nameref is a variable that is a reference to another variable. A nameref
is created with the -n attribute of typeset. The value of the variable at
the time of the typeset command becomes the variable that is referenced
whenever the nameref variable is used. The name of a nameref cannot
contain a dot (.). When a variable or function name contains a dot (.) and
the portion of the name up to the first . matches the name of a nameref,
the variable referred to is obtained by replacing the nameref portion with
the name of the variable referenced by the nameref. If a nameref is used
as the index of a for loop, a name reference is established for each item
in the list. A nameref provides a convenient way to refer to the variable
inside a function whose name is passed as an argument to a function. For
example, if the name of a variable is passed as the first argument to a
function, the command

typeset -n var=$1

inside the function causes references and assignments to var to be
references and assignments to the variable whose name has been passed to
the function. If any of the floating point attributes, -E, -F or -X, or
the integer attribute, -i, is set for vname, then the value is subject to
arithmetic evaluation as described in this manual page. Positional
parameters, parameters denoted by a number, can be assigned values with the
set special built-in command. Parameter $0 is set from argument zero when
the shell is invoked.

The character $ is used to introduce substitutable parameters.

${parameter}
The shell reads all the characters from ${ to the matching } as
part of the same word even if it contains braces or metacharacters.
The value, if any, of the parameter is substituted. The braces are
required when parameter is followed by a letter, digit, or
underscore that is not to be interpreted as part of its name or
when the variable name contains a dot (.). The braces are also
required when a variable is subscripted unless it is part of an
Arithmetic Expression or a Conditional Expression. If parameter is
one or more digits then it is a positional parameter. A positional
parameter of more than one digit must be enclosed in braces. If
parameter is * or @, then all the positional parameters, starting
with $1, are substituted and separated by a field separator
character. If an array vname with last subscript * or @ is used,
or for index arrays of the form sub1..sub2 is used, then the value
for each of the elements between sub1 and sub2 inclusive (or all
elements for * and @) is substituted, separated by the first
character of the value of IFS.

${#parameter}
If parameter is * or @, the number of positional parameters is
substituted. Otherwise, the length of the value of the parameter
is substituted.

${#vname[*]}
${#vname[@]}
The number of elements in the array vname is substituted.

${@vname}
Expands to the type name or attributes of the variable referred to
by vname. See Type Variables.

${!vname}
Expands to the name of the variable referred to by vname. This is
vname except when vname is a name reference.

${!vname[subscript]}
Expands to name of the subscript unless subscript is * or @, or of
the form sub1..sub2. When subscript is *, the list of array
subscripts for vname is generated. For a variable that is not an
array, the value is 0 if the variable is set, otherwise it is null.
When subscript is @, it is the same as ${ vname[*]}, except that
when used in double quotes, each array subscript yields a separate
argument. When subscript is of the form sub1..sub2 it expands to
the list of subscripts between sub1 and sub2 inclusive using the
same quoting rules as @.

${!prefix*}
Expands to the names of the variables whose names begin with
prefix.

${parameter:-word}
If parameter is set and is non-null then substitute its value.
Otherwise substitute word.

${parameter:=word}
If parameter is not set or is null, set it to word. The value of
the parameter is then substituted. Positional parameters cannot be
assigned to in this way.

${parameter:?word}
If parameter is set and is non-null, substitute its value.
Otherwise, print word and exit from the shell, if the shell is not
interactive. If word is omitted then a standard message is
printed.

${parameter:+word}
If parameter is set and is non-null, substitute word. Otherwise
substitute nothing.

In the above, word is not evaluated unless it is to be used as the
substituted string. In the following example, pwd is executed only if d is
not set or is NULL:

print ${d:-$(pwd)}

If the colon (:) is omitted from the expression, the shell only checks
whether parameter is set or not.

${parameter:offset:length}
${parameter:offset}
Expands to the portion of the value of parameter starting at the
character (counting from 0) determined by expanding offset as an
arithmetic expression and consisting of the number of characters
determined by the arithmetic expression defined by length.

In the second form, the remainder of the value is used. A negative
offset counts backwards from the end of parameter.

One or more BLANKs is required in front of a minus sign to prevent
the shell from interpreting the operator as :-. If parameter is *
or @, or is an array name indexed by * or @, then offset and length
refer to the array index and number of elements respectively. A
negative offset is taken relative to one greater than the highest
subscript for indexed arrays. The order for associative arrays is
unspecified.

${parameter#pattern}
${parameter##pattern}
If the shell pattern matches the beginning of the value of
parameter, then the value of this expansion is the value of the
parameter with the matched portion deleted. Otherwise the value of
this parameter is substituted. In the first form the smallest
matching pattern is deleted and in the second form the largest
matching pattern is deleted. When parameter is @, *, or an array
variable with subscript @ or *, the substring operation is applied
to each element in turn.

${parameter%pattern}
${parameter%%pattern}
If the shell pattern matches the end of the value of parameter,
then the value of this expansion is the value of the parameter with
the matched part deleted. Otherwise substitute the value of
parameter. In the first form the smallest matching pattern is
deleted, and in the second form the largest matching pattern is
deleted. When parameter is @, *, or an array variable with
subscript @ or *, the substring operation is applied to each
element in turn.

${parameter/pattern/string}
${parameter//pattern/string}
${parameter/#pattern/string}
${parameter/%pattern/string}
Expands parameter and replaces the longest match of pattern with
the specified string. Each occurrence of \n in string is replaced
by the portion of parameter that matches the nth sub-pattern.

When string is null, the pattern is deleted and the / in front of
string can be omitted. When parameter is @, *, or an array
variable with subscript @ or *, the substitution operation is
applied to each element in turn. In this case, the string portion
of word is re-evaluated for each element.

In the first form, only the first occurrence of pattern is
replaced.

In the second form, each match for pattern is replaced by the
specified string.

The third form restricts the pattern match to the beginning of the
string.

The fourth form restricts the pattern match to the end of the
string.

The following parameters are automatically set by the shell:

# The number of positional parameters in decimal.

- Options supplied to the shell on invocation or by the set command.

? The decimal value returned by the last executed command.

$ The process number of this shell.

_ Initially, the value of _ is the absolute pathname of the shell or
script being executed as passed in the environment. It is
subsequently assigned the last argument of the previous command.

This parameter is not set for commands which are asynchronous.
This parameter is also used to hold the name of the matching MAIL
file when checking for mail.

! The process id or the pool name and job number of the last
background command invoked or the most recent job put in the
background with the bg built-in command. Background jobs started
in a named pool with be in the form pool.number where pool is the
pool name and number is the job number within that pool.

.sh.command
When processing a DEBUG trap, this variable contains the current
command line that is about to run.

.sh.edchar
This variable contains the value of the keyboard character (or
sequence of characters if the first character is an ESC, (ASCII
033) that has been entered when processing a KEYBD trap. If the
value is changed as part of the trap action, then the new value
replaces the key (or key sequence) that caused the trap. See the
Key Bindings section of this manual page.

.sh.edcol
The character position of the cursor at the time of the most recent
KEYBD trap.

.sh.edmode
The value is set to ESC when processing a KEYBD trap while in vi
insert mode. Otherwise, .sh.edmode is null when processing a KEYBD
trap. See the vi Editing Mode section of this manual page.

.sh.edtext
The characters in the input buffer at the time of the most recent
KEYBD trap. The value is null when not processing a KEYBD trap.

.sh.file
The pathname of the file than contains the current command.

.sh.fun
The name of the current function that is being executed.

.sh.match
An indexed array which stores the most recent match and sub-pattern
matches after conditional pattern matches that match and after
variables expansions using the operators #, %, or /. The 0th
element stores the complete match and the ith element stores the
ith sub-match. The .sh.match variable is unset when the variable
that has expanded is assigned a new value.

.sh.math
Used for defining arithmetic functions (see Arithmetic evaluation)
and stores the list of user-defined arithmetic functions.

.sh.name
Set to the name of the variable at the time that a discipline
function is invoked.

.sh.subscript
Set to the name subscript of the variable at the time that a
discipline function is invoked.

.sh.subshell
The current depth for sub-shells and command substitution.

.sh.value
Set to the value of the variable at the time that the set or append
discipline function is invoked. When a user-defined arithmetic
function is invoked, the value of .sh.value is saved and .sh.value
is set to long double precision floating point. .sh.value is
restored when the function returns.

.sh.version
Set to a value that identifies the version of this shell.

LINENO The current line number within the script or function being
executed.

OLDPWD The previous working directory set by the cd command.

OPTARG The value of the last option argument processed by the getopts
built-in command.

OPTIND The index of the last option argument processed by the getopts
built-in command.

PPID The process number of the parent of the shell.

PWD The present working directory set by the cd command.

RANDOM Each time this variable is referenced, a random integer, uniformly
distributed between 0 and 32767, is generated. The sequence of
random numbers can be initialized by assigning a numeric value to
RANDOM.

REPLY This variable is set by the select statement and by the read built-
in command when no arguments are supplied.

SECONDS
Each time this variable is referenced, the number of seconds since
shell invocation is returned. If this variable is assigned a
value, then the value returned upon reference is the value that was
assigned plus the number of seconds since the assignment.

SHLVL An integer variable the is incremented each time the shell is
invoked and is exported. If SHLVL is not in the environment when
the shell is invoked, it is set to 1.

The following variables are used by the shell:

CDPATH Defines the search path for the cd command.

COLUMNS
Defines the width of the edit window for the shell edit modes and
for printing select lists.

EDITOR If the VISUAL variable is not set, the value of this variable is
checked for the patterns as described with VISUAL and the
corresponding editing option is turned on.

See the set command in the Special Commands section of this manual
page.

ENV Performs parameter expansion, command substitution, and arithmetic
substitution on the value to generate the pathname of the script
that is executed when the shell is invoked. This file is typically
used for alias and function definitions. The default value is
$HOME/.kshrc.

See the Invocation section of this manual page.

ENV is not set by the shell.

FCEDIT Obsolete name for the default editor name for the hist command.
FCEDIT is not used when HISTEDIT is set.

The shell specifies a default value to FCEDIT.

FIGNORE
A pattern that defines the set of file names that is ignored when
performing file name matching.

FPATH The search path for function definitions. The directories in this
path are searched for a file with the same name as the function or
command when a function with the -u attribute is referenced and
when a command is not found. If an executable file with the name
of that command is found, then it is read and executed in the
current environment. Unlike PATH, the current directory must be
represented explicitly by dot (.) rather than by adjacent colon (:)
characters or a beginning or ending colon (:).

HISTCMD
The number of the current command in the history file.

HISTEDIT
The name for the default editor name for the hist command.

HISTFILE
If this variable is set when the shell is invoked, the value is the
pathname of the file that is used to store the command history.
See the Command Re-entry section of this manual page.

HISTSIZE
If this variable is set when the shell is invoked, then the number
of previously entered commands that are accessible by this shell is
greater than or equal to this number. The default is 512.

HOME The default argument (home directory) for the cd command.

HOME is not set by the shell. HOME is set by login(1).

IFS Internal field separators, normally SPACE, TAB, and NEWLINE that
are used to separate the results of command substitution or
parameter expansion and to separate fields with the built-in
command read. The first character of the IFS variable is used to
separate arguments for the "$*" substitution. See the Quoting
section of this manual page.

Each single occurrence of an IFS character in the string to be
split, that is not in the issspace character class, and any
adjacent characters in IFS that are in the issspace character
class, delimit a field. One or more characters in IFS that belong
to the issspace character class, delimit a field. In addition, if
the same issspace character appears consecutively inside IFS, this
character is treated as if it were not in the issspace class, so
that if IFS consists of two tab characters, then two adjacent tab
characters delimit a null field.

The shell specifies a default value to IFS.

JOBMAX This variable defines the maximum number running background jobs
that can run at a time. When this limit is reached, the shell will
wait for a job to complete before starting a new job.

LANG This variable determines the locale category for any category not
specifically selected with a variable starting with LC_ or LANG.

LC_ALL This variable overrides the value of the LANG variable and any
other LC_ variable.

LC_COLLATE
This variable determines the locale category for character
collation information.

LC_CTYPE
This variable determines the locale category for character handling
functions. It determines the character classes for pattern
matching. See the File Name Generation section of this manual
page.

LC_NUMERIC
This variable determines the locale category for the decimal point
character.

LINES If this variable is set, the value is used to determine the column
length for printing select lists. Select lists prints vertically
until about two-thirds of LINES lines are filled.

MAIL If this variable is set to the name of a mail file and the MAILPATH
variable is not set, then the shell informs the user of arrival of
mail in the specified file.

MAIL is not set by the shell. On some systems, MAIL is set by
login(1).

MAILCHECK
Specifies how often in seconds the shell checks for changes in the
modification time of any of the files specified by the MAILPATH or
MAIL variables. The default value is 600 seconds. When the time
has elapsed the shell checks before issuing the next prompt.

The shell specifies a default value to MAILCHECK.

MAILPATH
A colon (:) separated list of file names. If this variable is set,
then the shell informs the user of any modifications to the
specified files that have occurred within the last MAILCHECK
seconds. Each file name can be followed by a ? and a message that
is printed. The message undergoes parameter expansion, command
substitution, and arithmetic substitution with the variable $_
defined as the name of the file that has changed. The default
message is `you have mail in $_'.

PATH The search path for commands. Except in .profile, users cannot
change PATH if executing under rksh93. See the Execution section
of this manual page.

The shell specifies a default value to PATH.

PS1 The value of this variable is expanded for parameter expansion,
command substitution, and arithmetic substitution to define the
primary prompt string which by default is $. The character ! in
the primary prompt string is replaced by the command number. Two
successive occurrences of ! produces a single ! when the prompt
string is printed. See the Command Re-entry section of this manual
page.

The shell specifies a default value to PS1.

PS2 Secondary prompt string, by default, >.

The shell specifies a default value to PS2.

PS3 Selection prompt string used within a select loop, by default #?.

The shell specifies a default value to PS3.

PS4 The value of this variable is expanded for parameter evaluation,
command substitution, and arithmetic substitution and precedes each
line of an execution trace. By default, PS4 is +. When PS4 is
unset, the execution trace prompt is also +.

The shell specifies a default value to PS4.

SHELL The pathname of the shell is kept in the environment. At
invocation, if the basename of this variable is rsh, rksh, rksh93,
or krsh, the shell becomes restricted.

SHELL is not set by the shell. On some systems, SHELL is set by
login(1).

TIMEFORMAT
The value of this parameter is used as a format string specifying
how the timing information for pipelines prefixed with the time
reserved word should be displayed. The % character introduces a
format sequence that is expanded to a time value or other
information.

The format sequences and their meanings are as follows.

%% A literal %.

%[p][l]R The elapsed time in seconds.

%[p][l]U The number of CPU seconds spent in user mode.

%[p][l]S The number of CPU seconds spent in system mode.

%P The CPU percentage, computed as(U+S)/R.

The braces denote optional portions. The optional p is a digit
specifying the precision, the number of fractional digits after a
decimal point. A value of 0 causes no decimal point or fraction to
be output. At most three places after the decimal point can be
displayed. Values of p greater than 3 are treated as 3. If p is
not specified, the value 3 is used.

The optional l specifies a longer format, including hours if
greater than zero, minutes, and seconds of the form HHhMMmSS.FFs.
The value of p determines whether or not the fraction is included.

All other characters are output without change and a trailing
NEWLINE is added. If unset, the default value:

$'\nreal\t%2lR\nuser\t%2lU\nsys%2lS'

is used. If the value is null, no timing information is displayed.

TMOUT If set to a value greater than zero, TMOUT is the default time-out
value for the read built-in command. The select compound command
terminates after TMOUT seconds when input is from a terminal.
Otherwise, the shell terminates if a line is not entered within the
prescribed number of seconds while reading from a terminal. The
shell can be compiled with a maximum bound for this value which
cannot be exceeded.

The shell specifies a default value to TMOUT.

VISUAL If the value of this variable matches the pattern *[Vv][Ii]*, then
the vi option is turned on. See Special Commands. If the value
matches the pattern *gmacs*, the gmacs option is turned on. If the
value matches the pattern *macs*, then the emacs option is turned
on. The value of VISUAL overrides the value of EDITOR.

Field Splitting

After parameter expansion and command substitution, the results of
substitutions are scanned for the field separator characters (those found
in IFS) and split into distinct fields where such characters are found.
Explicit null fields ( or '') are retained. Implicit null fields, those
resulting from parameters that have no values or command substitutions with
no output, are removed.

If the braceexpand (-B) option is set, each of the fields resulting from
IFS are checked to see if they contain one or more of the brace patterns.
Valid brace patterns are:

{*,*[,*]...}
{l1..l2}
{n1..n2}
{n1..n2%fmt}
{n1..n2..n3}
{n1..n2..n3%fmt}

where * represents any character, l1, l2 are letters and n1, n2, n3 are
signed numbers and fmt is a format specified as used by printf. In each
case, fields are created by prepending the characters before the { and
appending the characters after the } to each of the strings generated by
the characters between the { and }. The resulting fields are checked to
see if they have any brace patterns.

In the first form, a field is created for each string between { and the
first comma (`,'), between a pair of commas (`,') and between the last
comma (`,') and the terminating }. The string represented by * can contain
embedded matching { and } without quoting. Otherwise, each { and } within
* must be quoted.

In the second form, l1 and l2 must both be either upper case or both be
lower case characters in the C locale. In this case a field is created for
each character from l1 to l2 inclusive.

In the remaining forms, a field is created for each number starting at n1.
This continues until it reaches n2 and increments n1 by n3. The cases
where n3 is not specified behave as if n3 were 1 if n1 <= n2, and -1
otherwise.

In forms which specify %fmt, any format flags, widths and precisions can be
specified and fmt can end in any of the specifiers cdiouxX. For example,
{a,z}{1..5..3%02d}{b..c}x expands to the 8 fields, a01bx, a01cx, a04bx,
a04cx, z01bx, z01cx, z04bx, and z04cx.

File Name Generation

Following splitting, each field is scanned for the characters *, ?, (, and
[, unless the -f option has been set. If one of these characters appears,
then the word is regarded as a pattern.

Each file name component that contains any pattern character is replaced
with a lexicographically sorted set of names that matches the pattern from
that directory. If no file name is found that matches the pattern, then
that component of the file name is left unchanged unless the pattern is
prefixed with ~(N) in which case it is removed. If FIGNORE is set, then
each file name component that matches the pattern defined by the value of
FIGNORE is ignored when generating the matching file names. The names .
and .. are also ignored. If FIGNORE is not set, the character . at the
start of each file name component is ignored unless the first character of
the pattern corresponding to this component is the character . itself. For
other uses of pattern matching the / and . are not specially treated.

* Match any string, including the null string. When used for file
name expansion, if the globstar option is on, two adjacent *s by
themselves match all files and zero or more directories and
subdirectories. If the two adjacent *s are followed by a /, only
directories and subdirectories match.

? Matches any single character.

[...] Match any one of the enclosed characters. A pair of characters
separated by - matches any character lexically between the pair,
inclusive. If the first character following the opening [ is a !
or ^, any character not enclosed is matched. A - can be included
in the character set by putting it as the first or last character.
Within [ and ], character classes can be specified with the syntax
[:class:] where class is one of the following classes defined in
the ANSI-C standard:

alnum alpha blank cntrl digit graph
lower print punct space upper word
xdigit

word is equivalent to alnum plus the character _. Within [ and ],
an equivalence class can be specified with the syntax [=c=] which
matches all characters with the same primary collation weight (as
defined by the current locale) as the character c. Within [ and ],
[.symbol.] matches the collating symbol symbol.

A pattern-list is a list of one or more patterns separated from each other
with an & or |. An & signifies that all patterns must be matched whereas |
requires that only one pattern be matched. Composite patterns can be
formed with one or more of the following sub-patterns:

?(pattern-list) Optionally matches any one of the specified
patterns.

*(pattern-list) Matches zero or more occurrences of the specified
patterns.

+(pattern-list) Matches one or more occurrences of the specified
patterns.

{n}(pattern-list) Matches n occurrences of the specified patterns.

{m,n}(pattern-list) Matches from m to n occurrences of the specified
patterns. If m is omitted, 0 is used. If n is
omitted at least m occurrences are matched.

@(pattern-list) Matches exactly one of the specified patterns.

!(pattern-list) Matches anything except one of the specified
patterns.

By default, each pattern, or sub-pattern matches the longest string
possible consistent with generating the longest overall match. If more
than one match is possible, the one starting closest to the beginning of
the string is chosen. However, for each of the compound patterns a - can
be inserted in front of the ( to cause the shortest match to the specified
pattern-list to be used.

When pattern-list is contained within parentheses, the backslash character
(\) is treated specially even when inside a character class. All ANSI-C
character escapes are recognized and match the specified character. In
addition the following escape sequences are recognized:

\d Matches any character in the digit class.

\D Matches any character not in the digit class.

\s Matches any character in the space class.

\S Matches any character not in the space class.

\w Matches any character in the word class.

\W Matches any character not in the word class.

A pattern of the form %(pattern-pairs) is a sub-pattern that can be used to
match nested character expressions. Each pattern-pair is a two character
sequence which cannot contain & or |. The first pattern-pair specifies the
starting and ending characters for the match. Each subsequent pattern-pair
represents the beginning and ending characters of a nested group that is
skipped over when counting starting and ending character matches. The
behavior is unspecified when the first character of a pattern-pair is
alphanumeric except for the following:

D Causes the ending character to terminate the search for this
pattern without finding a match.

E Causes the ending character to be interpreted as an escape
character.

L Causes the ending character to be interpreted as a quote character
causing all characters to be ignored when looking for a match.

Q Causes the ending character to be interpreted as a quote character
causing all characters other than any escape character to be
ignored when looking for a match.

%({}Q"E\), matches characters starting at { until the matching } is found
not counting any { or } that is inside a double quoted string or preceded
by the escape character (\). Without the {} this pattern matches any C
language string.

Each sub-pattern in a composite pattern is numbered, starting at 1, by the
location of the ( within the pattern. The sequence \n, where n is a single
digit and \n, comes after the nth sub-pattern, matches the same string as
the sub-pattern itself.

A pattern can contain sub-patterns of the form ~(options:pattern-list),
where either options or :pattern-list can be omitted. Unlike the other
compound patterns, these sub-patterns are not counted in the numbered sub-
patterns. :pattern-list must be omitted for options F, G, N and V below.
If options is present, it can consist of one or more of the following:

+ Enable the following options. This is the default.

- Disable the following options.

E The remainder of the pattern uses extended regular expression
syntax like the egrep(1) command.

F The remainder of the pattern uses fgrep(1) expression syntax.

g File the longest match (greedy). This is the default.

G The remainder of the pattern uses basic regular expression syntax
like the grep(1) command.

i Treat the match as case insensitive.

K The remainder of the pattern uses shell pattern syntax. This is
the default.

l Left anchor the pattern.

This is the default for K style patterns.

N This is ignored. However, when it is the first letter and is used
with file name generation, and no matches occur, the file pattern
expands to the empty string.

r Right anchor the pattern.

This is the default for K style patterns.

X The remainder of the pattern uses augmented regular expression
syntax.

P The remainder of the pattern uses perl(1) regular expression
syntax. Not all perl regular expression syntax is currently
implemented.

V The remainder of the pattern uses System V regular expression
syntax.

If both options and :pattern-list are specified, then the options apply
only to pattern-list. Otherwise, these options remain in effect until they
are disabled by a subsequent ~(...) or at the end of the sub-pattern
containing ~(...).

Quoting

Each of the metacharacters listed in the Definitions section of this manual
page has a special meaning to the shell and causes termination of a word
unless quoted. A character can be quoted, that is, made to stand for
itself, by preceding it with a backslash (\). The pair \NEWLINE is
removed. All characters enclosed between a pair of single quote marks ('')
that is not preceded by a $ are quoted. A single quote cannot appear
within the single quotes. A single quoted string preceded by an unquoted $
is processed as an ANSI-C string except for the following:

\0 Causes the remainder of the string to be ignored.

\cx Expands to the character CTRL-x.

\C[.name.] Expands to the collating element name.

\e Equivalent to the escape character (ASCII 033).

\E Equivalent to the escape character (ASCII 033).

Inside double quote marks (""), parameter and command substitution occur
and \ quotes the characters \, `, ", and $. A $ in front of a double
quoted string is ignored in the C or POSIX locale, and might cause the
string to be replaced by a locale specific string otherwise. The meaning
of $* and $@ is identical when not quoted or when used as a variable
assignment value or as a file name. However, when used as a command
argument, "$*" is equivalent to "$1d$2d...", where d is the first character
of the IFS variable, whereas "$@" is equivalent to "$1" "$2" ... Inside
grave quote marks (``), \ quotes the characters \, `, and $. If the grave
quotes occur within double quotes, then \ also quotes the character ".

The special meaning of reserved words or aliases can be removed by quoting
any character of the reserved word. The recognition of function names or
built-in command names cannot be altered by quoting them.

Arithmetic Evaluation

The shell performs arithmetic evaluation for arithmetic substitution, to
evaluate an arithmetic command, to evaluate an indexed array subscript, and
to evaluate arguments to the built-in commands shift and let. Arithmetic
evaluation is also performed on argument operands of the built-in command
printf that correspond to numeric format specifiers in the format operand.
See printf(1). Evaluations are performed using double precision floating
point arithmetic or long double precision floating point for systems that
provide this data type. Floating point constants follow the ANSI-C
programming language floating point conventions. The floating point
constants Nan and Inf can be used to represent "not a number" and infinity
respectively. Integer constants follow the ANSI-C programming language
integer constant conventions although only single byte character constants
are recognized and character casts are not recognized. Constants can be of
the form [base#]n where base is a decimal number between two and sixty-four
representing the arithmetic base and n is a number in that base. The
digits greater than 9 are represented by the lower case letters, the upper
case letters, @, and _ respectively. For bases less than or equal to 36,
upper and lower case characters can be used interchangeably.

An arithmetic expression uses the same syntax, precedence, and
associativity of expression as the C language. All the C language
operators that apply to floating point quantities can be used. In
addition, the operator ** can be used for exponentiation. It has higher
precedence than multiplication and is left associative. When the value of
an arithmetic variable or subexpression can be represented as a long
integer, all C language integer arithmetic operations can be performed.
Variables can be referenced by name within an arithmetic expression without
using the parameter expansion syntax. When a variable is referenced, its
value is evaluated as an arithmetic expression.

Any of the following math library functions that are in the C math library
can be used within an arithmetic expression:

rint round sin sinh sqrt tan tanh tgamma trunc abs
acos acosh asin asinh atan atan2 atanh cbrt ceil copysign
cos cosh erf erfc exp exp2 expm1 fabs fpclassify fdim
finite floor fma fmax fmin fmod hypot ilogb int isfinite
sinf isnan isnormal issubnormal issubordered iszero j0
j1 jn lgamma log log10 log2 logb nearbyint nextafter
nexttoward pow remainder rint round scanb signbit sin sinh
sqrt tan tanh tgamma trunc y0 y1 yn

In addition, arithmetic functions can be defined as shell functions with a
variant of the function name syntax:

function .sh.math.name ident { list ;}

where name is the function name used in the arithmetic expression and each
identified ident is a name reference to the long double precision floating
point argument. The value of .sh.value when the function returns is the
value of this function. User defined functions can take up to 3 arguments
and override C math library functions.

An internal representation of a variable as a double precision floating
point can be specified with the -E[n], -F[n], or -X[n] options of the
typeset special built-in command. The -E option causes the expansion of
the value to be represented using scientific notation when it is expanded.
The optional option argument n defines the number of significant figures.
The -F option causes the expansion to be represented as a floating decimal
number when it is expanded. The optional option argument n defines the
number of places after the decimal point in this case. The -X option
causes the expansion to be represented using the %a format defined by ISO
C-99. The optional option argument n defines the number of places after
the decimal (or radix) point in this case.

An internal integer representation of a variable can be specified with the
-i[n] option of the typeset special built-in command. The optional option
argument n specifies an arithmetic base to be used when expanding the
variable. If you do not specify an arithmetic base, base 10 is used.

Arithmetic evaluation is performed on the value of each assignment to a
variable with the -E, -F, -X or -i option. Assigning a floating point
number to a variable whose type is an integer causes the fractional part to
be truncated.

Prompting

When used interactively, the shell prompts with the value of PS1 after
expanding it for parameter expansion, command substitution, and arithmetic
substitution, before reading a command. In addition, each single ! in the
prompt is replaced by the command number. A !! is required to place a
literal ! in the prompt. If at any time a NEWLINE is typed and further
input is needed to complete a command, then the secondary prompt, that is,
the value of PS2, is issued.

Conditional Expressions

A conditional expression is used with the [[ compound command to test
attributes of files and to compare strings. Field splitting and file name
generation are not performed on the words between [[ and ]].

Each expression can be constructed from one or more of the following unary
or binary expressions:

-a file True, if file exists.

This option is the same as -e. This option is obsolete.

-b file True, if file exists and is a block special file.

-c file True, if file exists and is a character special file.

-d file True, if file exists and is a directory.

-e file True, if file exists.

-f file True, if file exists and is an ordinary file.

-g file True, if file exists and it has its setgid bit set.

-G file True, if file exists and its group matches the effective
group id of this process.

-h file True, if file exists and is a symbolic link.

-k file True, if file exists and it has its sticky bit set.

-L file True, if file exists and is a symbolic link.

-n string True, if length of string is non-zero.

-N file True, if file exists and the modification time is greater
than the last access time.

-o option True, if option named option is on.

-o ?option True, if option named option is a valid option name.

-O file True, if file exists and is owned by the effective user id of
this process.

-p file True, if file exists and is a FIFO special file or a pipe.

-r file True, if file exists and is readable by current process.

-R name True if variable name is a name reference.

-s file True, if file exists and has size greater than zero.

-S file True, if file exists and is a socket.

-t fildes True, if file descriptor number fildes is open and associated
with a terminal device.

-u file True, if file exists and it has its setuid bit set.

-v name True, if variable name is a valid variable name and is set.

-w file True, if file exists and is writable by current process.

-x file True, if file exists and is executable by current process.
If file exists and is a directory, then true if the current
process has permission to search in the directory.

-z string True, if length of string is zero.

file1 -ef file2
True, if file1 and file2 exist and refer to the same file.

file1 -nt file2
True, if file1 exists and file2 does not, or file1 is newer
than file2.

file1 -ot file2
True, if file2 exists and file1 does not, or file1 is older
than file2.

string True, if string is not null.

string == pattern
True, if string matches pattern. Any part of pattern can be
quoted to cause it to be matched as a string. With a
successful match to pattern, the .sh.match array variable
contains the match and sub-pattern matches.

string = pattern
Same as ==, but is obsolete.

string != pattern
True, if string does not match pattern. When the string
matches the pattern the .sh.match array variable contains the
match and sub-pattern matches.

string =~ ere
True if string matches the pattern ~(E)ere where ere is an
extended regular expression.

string1 < string2
True, if string1 comes before string2 based on ASCII value of
their characters.

string1 > string2
True, if string1 comes after string2 based on ASCII value of
their characters.

In each of the above expressions, if file is of the form /dev/fd/n, where n
is an integer, the test is applied to the open file whose descriptor number
is n.

The following obsolete arithmetic comparisons are also supported:

exp1 -eq exp2 True, if exp1 is equal to exp2.

exp1 -ge exp2 True, if exp1 is greater than or equal to exp2.

exp1 -gt exp2 True, if exp1 is greater than exp2.

exp1 -le exp2 True, if exp1 is less than or equal to exp2.

exp1 -lt exp2 True, if exp1 is less than exp2.

exp1 -ne exp2 True, if exp1 is not equal to exp2.

A compound expression can be constructed from these primitives by using any
of the following, listed in decreasing order of precedence:

(expression)
True, if expression is true. Used to group expressions.

! expression
True, if expression is false.

expression1 && expression2
True, if expression1 and expression2 are both true.

expression1 || expression2
True, if either expression1 or expression2 is true.

Input and Output

Before a command is executed, its input and output can be redirected using
a special notation interpreted by the shell. The following can appear
anywhere in a simple command or can precede or follow a command and are not
passed on to the invoked command. Command substitution, parameter
expansion, and arithmetic substitution occur before word or digit is used
except as noted in this section. File name generation occurs only if the
shell is interactive and the pattern matches a single file. Field
splitting is not performed.

In each of the following redirections, if file is of the form /dev/sctp/
host/port, /dev/tcp/ host/port, or /dev/udp/ host/port, where host is a
hostname or host address, and port is a service specified by name or an
integer port number, then the redirection attempts to make a tcp, sctp or
udp connection to the corresponding socket.

No intervening space is allowed between the characters of redirection
operators.

<word Use file word as standard input (file descriptor 0).

>word Use file word as standard output (file descriptor 1). If the
file does not exist then it is created. If the file exists,
and the noclobber option is on, this causes an error,
otherwise, it is truncated to zero length.

>|word Same as >, except that it overrides the noclobber option.

>;word Write output to a temporary file. If the command completes
successfully rename it to word, otherwise, delete the
temporary file. >;word cannot be used with the exec(2)
built-in.

>>word Use file word as standard output. If the file exists, then
output is appended to it (by first seeking to the end-of-
file), otherwise, the file is created.

<>word Open file word for reading and writing as standard input.

<<[-]word The shell input is read up to a line that is the same as word
after any quoting has been removed, or to an end-of-file. No
parameter substitution, command substitution, arithmetic
substitution or file name generation is performed on word.
The resulting document, called a here-document, becomes the
standard input. If any character of word is quoted, then no
interpretation is placed upon the characters of the document.
Otherwise, parameter expansion, command substitution, and
arithmetic substitution occur, \NEWLINE is ignored, and \
must be used to quote the characters \, $ and `. If - is
appended to <<, then all leading tabs are stripped from word
and from the document. If # is appended to <<, then leading
SPACEs and TABs are stripped off the first line of the
document and up to an equivalent indentation is stripped from
the remaining lines and from word. A tab stop is assumed to
occur at every 8 columns for the purposes of determining the
indentation.

<<<word A short form of here document in which word becomes the
contents of the here-document after any parameter expansion,
command substitution, and arithmetic substitution occur.

<&digit The standard input is duplicated from file descriptor digit,
and similarly for the standard output using >& digit. See
dup(2).

<&digit- The file descriptor specified by digit is moved to standard
input. Similarly for the standard output using >&digit-.

<&- The standard input is closed. Similarly for the standard
output using >&-.

<&p The input from the co-process is moved to standard input.

>&p The output to the co-process is moved to standard output.

<#((expr)) Evaluate arithmetic expression expr and position file
descriptor 0 to the resulting value bytes from the start of
the file. The variables CUR and EOF evaluate to the current
offset and end-of-file offset respectively when evaluating
expr.

>#((expr)) The same as <# except applies to file descriptor 1.

<#pattern Seek forward to the beginning of the next line containing
pattern.

<##pattern The same as <#, except that the portion of the file that is
skipped is copied to standard output.

If one of the redirection operators is preceded by a digit, with no
intervening space, then the file descriptor number referred to is that
specified by the digit (instead of the default 0 or 1). If one of the
redirection operators other than >&- and the ># and <# forms, is preceded
by {varname} with no intervening space, then a file descriptor number > 10
is selected by the shell and stored in the variable varname. If >&- or the
any of the ># and <# forms is preceded by {varname} the value of varname
defines the file descriptor to close or position. For example:

... 2>&1

means file descriptor 2 is to be opened for writing as a duplicate of file
descriptor 1 and

exec [n]<file

means open file for reading and store the file descriptor number in
variable n. The order in which redirections are specified is significant.
The shell evaluates each redirection in terms of the (file_descriptor,
file) association at the time of evaluation. For example:

... 1>fname 2>&1

first associates file descriptor 1 with file fname. It then associates
file descriptor 2 with the file associated with file descriptor 1, that is,
fname. If the order of redirections were reversed, file descriptor 2 would
be associated with the terminal (assuming file descriptor 1 had been) and
then file descriptor 1 would be associated with file fname. If a command
is followed by & and job control is not active, the default standard input
for the command is the empty file /dev/null. Otherwise, the environment
for the execution of a command contains the file descriptors of the
invoking shell as modified by input and output specifications.

Environment

The environment is a list of name-value pairs that is passed to an executed
program in the same way as a normal argument list. See environ(7).

The names must be identifiers and the values are character strings. The
shell interacts with the environment in several ways. On invocation, the
shell scans the environment and creates a variable for each name found,
giving it the corresponding value and attributes and marking it export.
Executed commands inherit the environment. If the user modifies the values
of these variables or creates new ones, using the export or typeset -x
commands, they become part of the environment. The environment seen by any
executed command is thus composed of any name-value pairs originally
inherited by the shell, whose values can be modified by the current shell,
plus any additions which must be noted in export or typeset -x commands.
The environment for any simple-command or function can be augmented by
prefixing it with one or more variable assignments. A variable assignment
argument is a word of the form identifier=value. Thus:

TERM=450 cmd args

and

(export TERM; TERM=450; cmd args)

are equivalent (as far as the execution of cmd is concerned) except for
special built-in commands listed in the Built-Ins section, those that are
preceded with a dagger. If the obsolete -k option is set, all variable
assignment arguments are placed in the environment, even if they occur
after the command name.

The following example first prints a=b c and then c:

echo a=b c
set -k
echo a=b c

This feature is intended for use with scripts written for early versions of
the shell and its use in new scripts is strongly discouraged.

Functions

For historical reasons, there are two ways to define functions, the name()
syntax and the function name syntax. These are described in the Commands
section of this manual page.

Shell functions are read in and stored internally. Alias names are
resolved when the function is read. Functions are executed like commands
with the arguments passed as positional parameters. See the Execution
section of this manual page for details.

Functions defined by the function name syntax and called by name execute in
the same process as the caller and share all files and present working
directory with the caller. Traps caught by the caller are reset to their
default action inside the function. A trap condition that is not caught or
ignored by the function causes the function to terminate and the condition
to be passed on to the caller. A trap on EXIT set inside a function is
executed in the environment of the caller after the function completes.
Ordinarily, variables are shared between the calling program and the
function. However, the typeset special built-in command used within a
function defines local variables whose scope includes the current function.
They can be passed to functions that they call in the variable assignment
list that precedes the call or as arguments passed as name references.
Errors within functions return control to the caller.

Functions defined with the name() syntax and functions defined with the
function name syntax that are invoked with the . special built-in are
executed in the caller's environment and share all variables and traps with
the caller. Errors within these function executions cause the script that
contains them to abort.

The special built-in command return is used to return from function calls.

Function names can be listed with the -f or +f option of the typeset
special built-in command. The text of functions, when available, is also
listed with -f. Functions can be undefined with the -f option of the unset
special built-in command.

Ordinarily, functions are unset when the shell executes a shell script.
Functions that need to be defined across separate invocations of the shell
should be placed in a directory and the FPATH variable should contain the
name of this directory. They can also be specified in the ENV file.

Discipline Functions

Each variable can have zero or more discipline functions associated with
it. The shell initially understands the discipline names get, set, append,
and unset but on most systems others can be added at run time via the C
programming interface extension provided by the builtin built-in utility.
If the get discipline is defined for a variable, it is invoked whenever the
specified variable is referenced. If the variable .sh.value is assigned a
value inside the discipline function, the referenced variable is evaluated
to this value instead. If the set discipline is defined for a variable, it
is invoked whenever the specified variable is assigned a value. If the
append discipline is defined for a variable, it is invoked whenever a value
is appended to the specified variable. The variable .sh.value is specified
the value of the variable before invoking the discipline, and the variable
is assigned the value of .sh.value after the discipline completes. If
.sh.value is unset inside the discipline, then that value is unchanged. If
the unset discipline is defined for a variable, it is invoked whenever the
specified variable is unset. The variable is not unset unless it is unset
explicitly from within this discipline function.

The variable .sh.name contains the name of the variable for which the
discipline function is called, .sh.subscript is the subscript of the
variable, and .sh.value contains the value being assigned inside the set
discipline function. For the set discipline, changing .sh.value changes
the value that gets assigned. The variable _ is a reference to the
variable including the subscript if any. For the set discipline, changing
.sh.value will change the value that gets assigned. Finally, the expansion
${var.name}, when name is the name of a discipline, and there is no
variable of this name, is equivalent to the command substitution
${var.name;}.

Name Spaces

Commands and functions that are executed as part of the list of a namespace
command that modify variables or create new ones, create a new variable
whose name is the name of the name space as given by identifier preceded by
two dots (..). When a variable whose name is name is referenced, it is
first searched for using .identifier.name. Similarly, a function defined by
a command in the namespace list is created using the name space name
preceded by two dots (..).

When the list of a namespace command contains a namespace command, the
names of variables and functions that are created consist of the variable
or function name preceded by the list of identifiers, each preceded by two
dots (..).

Outside of a name space, a variable or function created inside a name space
can be referenced by preceding it with the name space name.

By default, variables staring with .sh are in the sh name space.

Typed Variables

Typed variables provide a way to create data structure and objects. A type
can be defined either by a shared library, by the enum built-in command
described below, or by using the -T option of the typeset built-in command.
With the -T option of typeset, the type name, specified as an option
argument to -T, is set with a compound variable assignment that defines the
type. Function definitions can appear inside the compound variable
assignment and these become discipline functions for this type and can be
invoked or redefined by each instance of the type. The function name
create is treated specially. It is invoked for each instance of the type
that is created but is not inherited and cannot be redefined for each
instance.

When a type is defined a special built-in command of that name is added.
These built-ins are declaration commands and follow the same expansion
rules as all the special built-in commands defined below that are preceded
by a dot (.). These commands can subsequently be used inside further type
definitions. The man page for these commands can be generated by using the
--man option or any of the other -- options described with getopts. The
-r, -a, -A, -h and -S options of typeset are permitted with each of these
new built-ins.

An instance of a type is created by invoking the type name followed by one
or more instance names. Each instance of the type is initialized with a
copy of the sub-variables except for sub-variables that are defined with
the -s option. Variables defined with -S are shared by all instances of
the type. Each instance can change the value of any sub-variable and can
also define new discipline functions of the same names as those defined by
the type definition as well as any standard discipline names. No
additional sub-variables can be defined for any instance.

When defining a type, if the value of a sub-variable is not set and the -r
attribute is specified, it causes the sub-variable to be a required sub-
variable. Whenever an instance of a type is created, all required sub-
variables must be specified. These sub-variables become readonly in each
instance.

When unset is invoked on a sub-variable within a type, and the -r attribute
has not been specified for this field, the value is reset to the default
value associative with the type. Invoking unset on a type instance not
contained within another type deletes all sub-variables and the variable
itself. A type definition can be derived from another type definition by
defining the first sub-variable name as _ and defining its type as the base
type. Any remaining definitions will be additions and modifications that
apply to the new type. If the new type name is the same is that of the
base type, the type will be replaced and the original type will no longer
be accessible.

The typeset command with -T and no option argument or operands will write
all the type definitions to standard output in a form that that can be read
in to create all the types.

Jobs

If the monitor option of the set command is turned on, an interactive shell
associates a job with each pipeline. It keeps a table of current jobs,
printed by the jobs command, and assigns them small integer numbers. When
a job is started asynchronously with &, the shell prints a line which looks
like:

[1] 1234

indicating that the job which was started asynchronously was job number 1
and had one (top-level) process, whose process id was 1234.

If you are running a job and wish to stop it, CTRL-z sends a STOP signal to
the current job. The shell normally displays a message that the job has
been stopped, and displays another prompt. You can then manipulate the
state of this job, putting it in the background with the bg command, or run
some other commands and then eventually bring the job back into the
foreground with the foreground command fg. A CTRL-z takes effect
immediately and is like an interrupt in that pending output and unread
input are discarded when it is typed.

A job being run in the background stops if it tries to read from the
terminal. Background jobs are normally allowed to produce output, but this
can be disabled by giving the command stty tostop. If you set this tty
option, then background jobs stop when they try to produce output like they
do when they try to read input.

A job pool is a collection of jobs started with list & associated with a
name.

There are several ways to refer to jobs in the shell. A job can be
referred to by the process id of any process of the job or by one of the
following:

%number The job with the specified number.

pool All the jobs in the job pool named by pool.

pool.number The job number number in the pool named by pool.

%string Any job whose command line begins with string.

%?string Any job whose command line contains string.

%% Current job.

%+ Equivalent to %%.

%- Previous job.

In addition, unless noted otherwise, wherever a job can be specified, the
name of a background job pool can be used to represent all the jobs in that
pool.

The shell learns immediately whenever a process changes state. It normally
informs you whenever a job becomes blocked so that no further progress is
possible, but only just before it prints a prompt. This is done so that it
does not otherwise disturb your work. The notify option of the set command
causes the shell to print these job change messages as soon as they occur.

When the monitor option is on, each background job that completes triggers
any trap set for CHLD.

When you try to leave the shell while jobs are running or stopped, you are
warned that

You have stopped(running) jobs.

You can use the jobs command to see what they are. If you immediately try
to exit again, the shell does not warn you a second time, and the stopped
jobs are terminated. When a login shell receives a HUP signal, it sends a
HUP signal to each job that has not been disowned with the disown built-in
command.

Signals

The INT and QUIT signals for an invoked command are ignored if the command
is followed by & and the monitor option is not active. Otherwise, signals
have the values inherited by the shell from its parent. See the trap
built-in command.

Execution

Each time a command is read, the substitutions are carried out. If the
command name matches one of the ones in the Special Built-in Commands
section of this manual page, it is executed within the current shell
process. Next, the command name is checked to see if it matches a user
defined function. If it does, the positional parameters are saved and then
reset to the arguments of the function call. A function is also executed
in the current shell process. When the function completes or issues a
return, the positional parameter list is restored. For functions defined
with the function name syntax, any trap set on EXIT within the function is
executed. The exit value of a function is the value of the last command
executed. If a command name is not a special built-in command or a user
defined function, but it is one of the built-in commands, it is executed in
the current shell process.

The shell variables PATH and FPATH define the search path for the directory
containing the command. Alternative directory names are separated by a
colon (:). The default path is /bin:/usr/bin:, specifying /bin, /usr/bin,
and the current directory in that order. The current directory can be
specified by two or more adjacent colons, or by a colon at the beginning or
end of the path list. If the command name contains a slash (/), the search
path is not used. Otherwise, each directory in the list of directories
defined by PATH and FPATH is checked in order. If the directory being
searched is contained in the value of the FPATH variable and contains a
file whose name matches the command being searched, then this file is
loaded into the current shell environment as if it were the argument to the
. command except that only preset aliases are expanded, and a function of
the specified name is executed as described in this manual page.

If this directory is not in FPATH, the shell first determines whether there
is a built-in version of a command corresponding to a given pathname and,
if so, it is invoked in the current process. If no built-in is found, the
shell checks for a file named .paths in this directory. If found and there
is a line of the form:

FPATH=path

where path is an existing directory, then that directory is searched
immediately after the current directory as if it were found in the FPATH
variable. If path does not begin with /, it is checked for relative to the
directory being searched.

The .paths file is then checked for a line of the form:

PLUGIN_LIB=libname[:libname]...

Each library named by libname will be searched for as if it were an option
argument to builtin -f and, if it contains a built-in of the specified
name, this is executed instead of a command by this name.

Any built-in loaded from a library found this way will be associated with
the directory containing the .paths file so it will only execute if not
found in an earlier directory.

Finally, the directory will be checked for a file of the given name. If
the file has execute permission but is not an a.out file, it is assumed to
be a file containing shell commands. A separate shell is spawned to read
it. All non-exported variables are removed in this case. If the shell
command file doesn't have read permission, and/or if the setuid and setgid
bits are set on the file, then the shell executes an agent whose job it is
to set up the permissions and execute the shell with the shell command file
passed down as an open file. If the .paths contains a line of the form:

name=value

in the first or second line, then the environment variable name is modified
by prepending the directory specified by value to the directory list. If
value is not an absolute directory, then it specifies a directory relative
to the directory in which the executable was found. If the environment
variable name does not already exist it will be added to the environment
list for the specified command. A parenthesized command is executed in a
sub-shell without removing non-exported variables.

Command Re-entry
The text of the last HISTSIZE (default 512) commands entered from a
terminal device is saved in a history file. The file $HOME/.sh_history is
used if the HISTFILE variable is not set or if the file it names is not
writable. A shell can access the commands of all interactive shells which
use the same named HISTFILE. The built-in command hist is used to list or
edit a portion of this file. The portion of the file to be edited or
listed can be selected by number or by giving the first character or
characters of the command. A single command or range of commands can be
specified. If you do not specify an editor program as an argument to hist
then the value of the variable HISTEDIT is used. If HISTEDIT is unset, the
obsolete variable FCEDIT is used. If FCEDIT is not defined, then /bin/ed
is used. The edited commands are printed and executed again upon leaving
the editor unless you quit without writing. The -s option (and in obsolete
versions, the editor name -) is used to skip the editing phase and to re-
execute the command. In this case a substitution parameter of the form
old=new can be used to modify the command before execution. For example,
with the preset alias r, which is aliased to hist -s, typing `r bad=good c'
re-executes the most recent command which starts with the letter c,
replacing the first occurrence of the string `bad' with the string `good'.

Inline Editing Options

Normally, each command line entered from a terminal device is simply typed
followed by a NEWLINE (RETURN or LINE FEED). If either the emacs, gmacs,
or vi option is active, the user can edit the command line. To be in
either of these edit modes set the corresponding option. An editing option
is automatically selected each time the VISUAL or EDITOR variable is
assigned a value ending in either of these option names.

The editing features require that the user's terminal accept RETURN as
carriage return without line feed and that a SPACE must overwrite the
current character on the screen.

Unless the multiline option is on, the editing modes implement a concept
where the user is looking through a window at the current line. The window
width is the value of COLUMNS if it is defined, otherwise 80. If the
window width is too small to display the prompt and leave at least 8
columns to enter input, the prompt is truncated from the left. If the line
is longer than the window width minus two, a mark is displayed at the end
of the window to notify the user. As the cursor moves and reaches the
window boundaries the window is centered about the cursor. The mark is a >
(<, *) if the line extends on the right, left, or both sides of the window.

The search commands in each edit mode provide access to the history file.
Only strings are matched, not patterns, although a leading ^ in the string
restricts the match to begin at the first character in the line.

Each of the edit modes has an operation to list the files or commands that
match a partially entered word. When applied to the first word on the
line, or the first word after a ;, |, &, or (, and the word does not begin
with ~ or contain a /, the list of aliases, functions, and executable
commands defined by the PATH variable that could match the partial word is
displayed. Otherwise, the list of files that match the specified word is
displayed. If the partially entered word does not contain any file
expansion characters, a * is appended before generating these lists. After
displaying the generated list, the input line is redrawn. These operations
are called command name listing and file name listing, respectively. There
are additional operations, referred to as command name completion and file
name completion, which compute the list of matching commands or files, but
instead of printing the list, replace the current word with a complete or
partial match. For file name completion, if the match is unique, a / is
appended if the file is a directory and a space is appended if the file is
not a directory. Otherwise, the longest common prefix for all the matching
files replaces the word. For command name completion, only the portion of
the file names after the last / are used to find the longest command
prefix. If only a single name matches this prefix, then the word is
replaced with the command name followed by a space. When using a TAB for
completion that does not yield a unique match, a subsequent TAB provides a
numbered list of matching alternatives. A specific selection can be made
by entering the selection number followed by a TAB.

Key Bindings

The KEYBD trap can be used to intercept keys as they are typed and change
the characters that are actually seen by the shell. This trap is executed
after each character (or sequence of characters when the first character is
ESC) is entered while reading from a terminal.

The variable .sh.edchar contains the character or character sequence which
generated the trap. Changing the value of .sh.edchar in the trap action
causes the shell to behave as if the new value were entered from the
keyboard rather than the original value. The variable .sh.edcol is set to
the input column number of the cursor at the time of the input. The
variable .sh.edmode is set to ESC when in vi insert mode and is null
otherwise. By prepending ${.sh.editmode} to a value assigned to .sh.edchar
it causes the shell to change to control mode if it is not already in this
mode.

This trap is not invoked for characters entered as arguments to editing
directives, or while reading input for a character search.

emacs Editing Mode
This mode is entered by enabling either the emacs or gmacs option. The
only difference between these two modes is the way they handle ^T. To
edit, the user moves the cursor to the point needing correction and then
inserts or deletes characters or words as needed. All the editing commands
are control characters or escape sequences.

The notation for control characters is caret (^) followed by the character.

For example, ^F is the notation for CTRL/F. This is entered by depressing
f while holding down the CTRL (control) key. The SHIFT key is not
depressed. (The notation ^? indicates the DEL (delete) key).

The notation for escape sequences is M- followed by a character. For
example, M-f (pronounced Meta f) is entered by depressing ESC (ASCII 033)
followed by `f'. M-F is the notation for ESC followed by `F'.

All edit commands operate from any place on the line, not just at the
beginning. The RETURN or the LINE FEED key is not entered after edit
commands except when noted.

^F Move the cursor forward (right) one character.

M-[C Move the cursor forward (right) one character.

M-f Move the cursor forward one word. The emacs editor's idea of
a word is a string of characters consisting of only letters,
digits and underscores.

^B Move the cursor backward (left) one character.

M-[D Move the cursor backward (left) one character.

M-b Move the cursor backward one word.

^A Move the cursor to the beginning of the line.

M-[H Move the cursor to the beginning of the line.

^E Move the cursor to the end of the line.

M-[Y Move the cursor to the end of line.

^]char Move the cursor forward to the character char on the current
line.

M-^]char Move the cursor backwards to the character char on the
current line.

^X^X Interchange the cursor and the mark.

erase Delete the previous character. The user-defined erase
character is defined by the stty(1) command, and is usually
^H or #.

lnext Removes the next character's editing features. The user-
defined literal next character is defined by the stty(1)
command, or is ^V if not defined.

^D Delete the current character.

M-d Delete the current word.

M-^H MetaBACKSPACE. Delete the previous word.

M-h Delete the previous word.

M-^? MetaDEL. Delete the previous word. If your interrupt
character is ^? (DEL, the default), this command does not
work.

^T Transpose the current character with the previous character,
and advance the cursor in emacs mode. Transpose two previous
characters in gmacs mode.

^C Capitalize the current character.

M-c Capitalize the current word.

M-l Change the current word to lower case.

^K Delete from the cursor to the end of the line. If preceded
by a numerical parameter whose value is less than the current
cursor position, delete from specified position up to the
cursor. If preceded by a numerical parameter whose value is
greater than the current cursor position, then delete from
cursor up to specified cursor position.

^W Kill from the cursor to the mark.

M-p Push the region from the cursor to the mark on the stack.

kill Kill the entire current line. The user-defined kill
character is defined by the stty(1) command, usually a ^G or
@. If two kill characters are entered in succession, all
kill characters from then on cause a line feed. This is
useful when using paper terminals.

^Y Restore the last item removed from line. Yank the item back
to the line.

^L Line feed and print the current line.

M-^L Clear the screen.

^@ Null character. Set mark.

M-space MetaSPACE. Set the mark.

^J New line. Execute the current line.

^M Return. Execute the current line.

EOF End-of-file character, normally ^D, is processed as an
end-of-file only if the current line is null.

^P Fetch the previous command. Each time ^P is entered the
previous command back in time is accessed. Moves back one
line when it is not on the first line of a multi-line
command.

M-[A Equivalent to ^P.

M-< Fetch the least recent (oldest) history line.

M-> Fetch the most recent (youngest) history line.

^N Fetch the next command line. Each time ^N is entered the
next command line forward in time is accessed.

M-[B Equivalent to ^N.

^Rstring Reverse search history for a previous command line containing
string. If a parameter of zero is specified, the search is
forward. string is terminated by a RETURN or NEWLINE. If
string is preceded by a ^, the matched line must begin with
string. If string is omitted, then the next command line
containing the most recent string is accessed. In this case
a parameter of zero reverses the direction of the search.

^O Operate. Execute the current line and fetch the next line
relative to current line from the history file.

M-digits Escape. Define numeric parameter. The digits are taken as a
parameter to the next command. The commands that accept a
parameter are: ^F, ^B, ERASE, ^C, ^D, ^K, ^R, ^P, ^N, ^],
M-., M-, M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l, and
M-^H.

M-letter Soft-key. Search the alias list for an alias by the name
letter. If an alias of letter is defined, insert its value
on the input queue. letter must not be one of the
metafunctions in this section.

M-[letter Soft key. Search the alias list for an alias by the name
letter. If an alias of this name is defined, insert its
value on the input queue. This can be used to program
function keys on many terminals.

M-. The last word of the previous command is inserted on the
line. If preceded by a numeric parameter, the value of this
parameter determines which word to insert rather than the
last word.

M-_ Same as M-..

M-* Attempt filename generation on the current word. As asterisk
is appended if the word does not match any file or contain
any special pattern characters.

M-ESC Command or file name completion as described in this manual
page.

^I (TAB) Attempts command or file name completion as described in this
manual page. If a partial completion occurs, repeating this
behaves as if M-= were entered. If no match is found or
entered after SPACE, a TAB is inserted.

M-= If not preceded by a numeric parameter, generates the list of
matching commands or file names as described in this manual
page. Otherwise, the word under the cursor is replaced by
the item corresponding to the value of the numeric parameter
from the most recently generated command or file list. If
the cursor is not on a word, the word is inserted instead.

^U Multiply parameter of next command by 4.

\ Escape the next character. Editing characters, the user's
erase, kill and interrupt (normally ^?) characters can be
entered in a command line or in a search string if preceded
by a \. The \ removes the next character's editing features,
if any.

M-^V Display the version of the shell.

M-# If the line does not begin with a #, a # is inserted at the
beginning of the line and after each NEWLINE, and the line is
entered. This causes a comment to be inserted in the history
file. If the line begins with a #, the # is deleted and one
# after each NEWLINE is also deleted.

vi Editing Mode
There are two typing modes. Initially, when you enter a command you are in
the input mode. To edit, the user enters control mode by typing ESC (033)
and moves the cursor to the point needing correction and then inserts or
deletes characters or words as needed. Most control commands accept an
optional repeat count prior to the command.

When in vi mode on most systems, canonical processing is initially enabled
and the command is echoed again if the speed is 1200 baud or greater and it
contains any control characters or less than one second has elapsed since
the prompt was printed. The ESC character terminates canonical processing
for the remainder of the command and the user can then modify the command
line. This scheme has the advantages of canonical processing with the
type-ahead echoing of raw mode.

If the option viraw is also set, the terminal is always have canonical
processing disabled. This mode is implicit for systems that do not support
two alternate end of line delimiters, and might be helpful for certain
terminals.

Input Edit Commands

By default the editor is in input mode.

The following input edit commands are supported:

ERASE User defined erase character as defined by the stty(1) command,
usually ^H or #. Delete previous character.

^W Delete the previous blank separated word. On some systems the
viraw option might be required for this to work.

EOF As the first character of the line causes the shell to terminate
unless the ignoreeof option is set. Otherwise this character is
ignored.

lnext User defined literal next character as defined by stty(1) or ^V if
not defined. Removes the next character's editing features, if
any. On some systems the viraw option might be required for this
to work.

\ Escape the next ERASE or KILL character.

^I (TAB)
Attempts command or file name completion as described in this
manual page and returns to input mode. If a partial completion
occurs, repeating this behaves as if = were entered from control
mode. If no match is found or entered after SPACE, a TAB is
inserted.

Motion Edit Commands

The motion edit commands move the cursor.

The following motion edit commands are supported:

[count]l Move the cursor forward (right) one character.

[count][C Move the cursor forward (right) one character.

[count]w Move the cursor forward one alphanumeric word.

[count]W Move the cursor to the beginning of the next word that
follows a blank.

[count]e Move the cursor to the end of the word.

[count]E Move the cursor to the end of the current blank delimited
word.

[count]h Move the cursor backward (left) one character.

[count][D Move the cursor backward (left) one character.

[count]b Move the cursor backward one word.

[count]B Move the cursor to the preceding blank separated word.

[count]| Move the cursor to column count.

[count]fc Find the next character c in the current line.

[count]Fc Find the previous character c in the current line.

[count]fc Equivalent to f followed by h.

[count]Tc Equivalent to F followed by l.

[count]; Repeat count times the last single character find command: f,
F, t, or T.

[count], Reverse the last single character find command count times.

0 (zero) Move the cursor to the start of line.

^ Move the cursor to the first non-blank character in the line.

[H Move the cursor to the first non-blank character in the line.

$ Move the cursor to the end of the line.

[Y Move the cursor to the end of the line.

% Moves to the balancing (, ), {, }, [, or ]. If cursor is not
on one of the characters described in this section, the
remainder of the line is searched for the first occurrence of
one of the characters first.

Search Edit Commands

The search edit commands access your command history.

The following search edit commands are supported:

[count]k Fetch the previous command. Each time k is entered, the
previous command back in time is accessed.

[count]- Fetch the previous command. Each time - is entered, the
previous command back in time is accessed. Equivalent to k.

[count][A Fetch the previous command. Each time [A is entered, the
previous command back in time is accessed. Equivalent to k.

[count]j Fetch the next command. Each time j is entered, the next
command forward in time is accessed.

[count]+ Fetch the next command. Each time + is entered, the next
command forward in time is accessed. Equivalent to j.

[count][B Fetch the next command. Each time [B is entered, the next
command forward in time is accessed. Equivalent to j.

[count]G Fetch command number count. The default is the least recent
history command.

/string Search backward through history for a previous command
containing string. string is terminated by a RETURN or
NEWLINE. If string is preceded by a ^, the matched line must
begin with string. If string is null, the previous string is
used.

?string Search forward through history for a previous command
containing string. string is terminated by a RETURN or
NEWLINE. If string is preceded by a ^, the matched line must
begin with string. If string is null, the previous string is
used.

Same as / except that search is in the forward direction.

n Search in the backwards direction for the next match of the
last pattern to / or ? commands.

N Search in the forward direction for next match of the last
pattern to / or ? commands.

Text Modification Edit Commands

The following commands modify the line:

a Enter input mode and enter text after the current character.

A Append text to the end of the line. Equivalent to $a.

[count]cmotion
c[count]motion
Delete current character through to the character that motion
would move the cursor to, and enter input mode. If motion is
c, the entire line is deleted and input mode is entered.

C Delete the current character through to the end of line and
enter input mode. Equivalent to c$.

S Equivalent to cc.

[count]s Replace characters under the cursor in input mode.

D[count]dmotion
Delete the current character through to the end of line.
Equivalent to d$.

d [count]motion
Delete current character through to the character that motion
would move to. If motion is d, the entire line is deleted.

i Enter input mode and insert text before the current
character.

I Insert text before the beginning of the line. Equivalent to
0i.

[count]P Place the previous text modification before the cursor.

[count]p Place the previous text modification after the cursor.

R Enter input mode and replace characters on the screen with
characters you type overlay fashion.

[count]rc Replace the count characters starting at the current cursor
position with c, and advance the cursor.

[count]x Delete current character.

[count]X Delete preceding character.

[count]. Repeat the previous text modification command.

[count]~ Invert the case of the count characters starting at the
current cursor position and advance the cursor.

[count]_ Causes the count word of the previous command to be appended
and input mode entered. The last word is used if count is
omitted.

* Causes an * to be appended to the current word and file name
generation attempted. If no match is found, it rings the
bell. Otherwise, the word is replaced by the matching
pattern and input mode is entered.

\ Command or file name completion as described in this manual
page.

Other Edit Commands

The following miscellaneous edit commands are supported:

[count]ymotion
y[count]motion
Yank the current character through to the character to which
motion would move the cursor. Put the yanked characters in
the delete buffer. The text and cursor position are
unchanged.

yy Yank the current line.

Y Yank the current line from the current cursor location to the
end of the line. Equivalent to y$.

u Undo the last text modifying command.

U Undo all the text modifying commands performed on current
line.

[count]V Return the command:

hist -e ${VISUAL:-${EDITOR:-vi}} count

in the input buffer. If count is omitted, the current line
is used.

^L Line feed and print the current line. This command only
works in control mode.

^J New line. Execute the current line, regardless of mode.

^M Return. Execute the current line, regardless of mode.

# If the first character of the command is a #, delete this #
and each # that follows a NEWLINE.

Otherwise, send the line after inserting a # in front of each
line in the command.

This is command is useful for causing the current line to be
inserted in the history as a comment and un-commenting
previously commented commands in the history file.

[count]= If count is not specified, generate the list of matching
commands or file names as described in this manual page.

Otherwise, replace the word at the current cursor location
with the count item from the most recently generated command
or file list. If the cursor is not on a word, it is inserted
after the current cursor location.

@letter Search your alias list for an alias by the name letter. If
an alias of this name is defined, insert its value on the
input queue for processing.

^V Display version of the shell.

Built-in Commands
The following simple-commands are executed in the shell process. Input and
output redirection is permitted. Unless otherwise indicated, the output is
written on file descriptor 1 and the exit status, when there is no syntax
error, is 0. Except for :, true, false, echo, newgrp, and login, all
built-in commands accept -- to indicate the end of options. They also
interpret the option --man as a request to display the manual page onto
standard error and -? as a help request which prints a usage message on
standard error.

In the list below, commands that are preceded by one or two + symbols are
special built-in commands and are treated specially in the following ways:

1. Variable assignment lists preceding the command remain in effect
when the command completes.

2. I/O redirections are processed after variable assignments.

3. Errors cause a script that contains them to abort.

4. They are not valid function names.

5. Words following a command preceded by ++ that are in the format
of a variable assignment are expanded with the same rules as a
variable assignment. This means that tilde substitution is
performed after the = sign and field splitting and file name
generation are not performed.

+ : [arg ...]
The command only expands parameters.

+ . name [arg ...]
If name is a function defined with the function name reserved word
syntax, the function is executed in the current environment (as if
it had been defined with the name() syntax). Otherwise if name
refers to a file, the file is read in its entirety and the commands
are executed in the current shell environment. The search path
specified by PATH is used to find the directory containing the
file. If any arguments arg are specified, they become the
positional parameters while processing the . command and the
original positional parameters are restored upon completion.
Otherwise the positional parameters are unchanged. The exit status
is the exit status of the last command executed.

++ alias [-ptx] [name[=value]] ...
alias with no arguments prints the list of aliases in the form
name=value on standard output. The -p option causes the word alias
to be inserted before each one. When one or more arguments are
specified, an alias is defined for each name whose value is
specified. A trailing space in value causes the next word to be
checked for alias substitution. The obsolete -t option is used to
set and list tracked aliases. The value of a tracked alias is the
full pathname corresponding to the specified name. The value
becomes undefined when the value of PATH is reset but the alias
remains tracked. Without the -t option, for each name in the
argument list for which no value is specified, the name and value
of the alias is printed. The obsolete -x option has no effect.
The exit status is non-zero if a name is specified, but no value,
and no alias has been defined for the name.

bg [job ...]
This command is only on systems that support job control. Puts
each specified job into the background. The current job is put in
the background if job is not specified. See the Jobs section of
this manual page for a description of the format of job.

+ break [n]
Exit from the enclosing for, while, until, or select loop, if any.
If n is specified, then break n levels.

builtin [-ds] [-f file] [name ...]
If name is not specified, and no -f option is specified, the built-
ins are printed on standard output. The -s option prints only the
special built-ins. Otherwise, each name represents the pathname
whose basename is the name of the built-in. The entry point
function name is determined by prepending b_ to the built-in name.
A built-in specified by a pathname will only be executed when that
pathname would be found during the path search. Built-ins found in
libraries loaded via the .paths file will be associated with the
pathname of the directory containing the .paths file.

The ISO C/C++ prototype is int b_mycommand(int argc, char **argv,
Shbltin_t *context) for the built-in command mycommand where argv
is an array of argc elements and context is an optional pointer to
a Shbltin_t structure as described in <ast/shell.h> Special built-
ins cannot be bound to a pathname or deleted. The -d option
deletes each of the specified built-ins. On systems that support
dynamic loading, the -f option names a shared library containing
the code for built-ins. The shared library prefix and/or suffix,
which depend on the system, can be omitted. Once a library is
loaded, its symbols become available for subsequent invocations of
builtin. Multiple libraries can be specified with separate
invocations of the builtin command. Libraries are searched in the
reverse order in which they are specified. When a library is
loaded, it looks for a function in the library whose name is
lib_init() and invokes this function with an argument of 0.

cd [-LP] [arg]
cd [-LP] old new
This command has two forms.

In the first form it changes the current directory to arg. If arg
is a literal -, the directory is changed to the previous directory.
The shell variable HOME is the default arg. The variable PWD is
set to the current directory. The shell variable CDPATH defines
the search path for the directory containing arg. Alternative
directory names are separated by a colon (:). The default path is
NULL (specifying the current directory). The current directory is
specified by a null path name, which can appear immediately after
the equal sign or between the colon delimiters anywhere else in the
path list. If arg begins with a /, the search path is not used.
Otherwise, each directory in the path is searched for arg.

The second form of cd substitutes the string new for the string old
in the current directory name, PWD, and tries to change to this new
directory.

By default, symbolic link names are treated literally when finding
the directory name. This is equivalent to the -L option. The -P
option causes symbolic links to be resolved when determining the
directory. The last instance of -L or -P on the command line
determines which method is used. The cd command cannot be executed
by rksh93.

command [-pvVx] name [arg ...]
Without the -v or -V options, executes name with the arguments
specified by arg.

The -p option causes a default path to be searched rather than the
one defined by the value of PATH. Functions are not searched when
finding name. In addition, if name refers to a special built-in,
none of the special properties associated with the leading daggers
are honored. For example, the predefined alias redirect='command
exec' prevents a script from terminating when an invalid
redirection is specified.

With the -x option, if command execution would result in a failure
because there are too many arguments, E2BIG, the shell invokes
command name multiple times with a subset of the arguments on each
invocation. Arguments that occur prior to the first word that
expands to multiple arguments and after the last word that expands
to multiple arguments are passed on each invocation. The exit
status is the maximum invocation exit status.

With the -v option, command is equivalent to the built-in whence
command described in this section. The -V option causes command to
act like whence -v.

+ continue [n]
Resumes the next iteration of the enclosing for, while, until, or
select loop. If n is specified, then resume at the nth enclosing
loop.

disown [job ...]
Causes the shell not to send a HUP signal to each specified job, or
all active jobs if job is omitted, when a login shell terminates.

echo [arg ...]
When the first arg does not begin with a -, and none of the
arguments contain a backslash (\), prints each of its arguments
separated by a SPACE and terminated by a NEWLINE. Otherwise, the
behavior of echo is system dependent and print or printf described
in this section should be used. See echo(1) for usage and
description.

++ enum [-i] type[=(value ...)]
Creates a declaration command named type that is an integer type
that allows one of the specified values as enumeration names. If
=(value ...) is omitted, then type must be an indexed array
variable with at least two elements and the values are taken from
this array variable. If -i is specified the values are case
insensitive.

+ eval [arg ...]
The arguments are read as input to the shell and the resulting
commands are executed.

+ exec [-c] [-a name ...] [arg ...]
If arg is specified, the command specified by the arguments is
executed in place of this shell without creating a new process.
The -c option causes the environment to be cleared before applying
variable assignments associated with the exec invocation. The -a
option causes name rather than the first arg, to become argv[0] for
the new process. Input and output arguments can appear and affect
the current process. If arg is not specified, the effect of this
command is to modify file descriptors as prescribed by the
input/output redirection list. In this case, any file descriptor
numbers greater than 2 that are opened with this mechanism are
closed when invoking another program.

+ exit [n]
Causes the shell to exit with the exit status specified by n. The
value is the least significant 8 bits of the specified status. If
n is omitted, then the exit status is that of the last command
executed. An end-of-file also causes the shell to exit except for
a shell which has the ignoreeof option turned on. See set.

++ export [-p] [name[=value]] ...
If name is not specified, the names and values of each variable
with the export attribute are printed with the values quoted in a
manner that allows them to be re-entered. The export command is
the same as typeset -x except that if you use export within a
function, no local variable is created. The -p option causes the
word export to be inserted before each one. Otherwise, the
specified name s are marked for automatic export to the environment
of subsequently-executed commands.

false Does nothing, and exits 1. Used with until for infinite loops.

fg [job ...]
This command is only on systems that support job control. Each job
specified is brought to the foreground and waited for in the
specified order. Otherwise, the current job is brought into the
foreground. See Jobs for a description of the format of job.

getconf [name [pathname]]
Prints the current value of the configuration parameter specified
by name. The configuration parameters are defined by the IEEE
POSIX 1003.1 and IEEE POSIX 1003.2 standards. See pathconf(2) and
sysconf(3C).

The pathname argument is required for parameters whose value
depends on the location in the file system. If no arguments are
specified, getconf prints the names and values of the current
configuration parameters. The pathname / is used for each of the
parameters that requires pathname.

getopts [-a name] optstring vname [arg ...]
Checks arg for legal options. If arg is omitted, the positional
parameters are used. An option argument begins with a + or a -.
An option that does not begin with + or - or the argument -- ends
the options. Options beginning with + are only recognized when
optstring begins with a +. optstring contains the letters that
getopts recognizes. If a letter is followed by a :, that option is
expected to have an argument. The options can be separated from
the argument by blanks. The option -? causes getopts to generate a
usage message on standard error. The -a option can be used to
specify the name to use for the usage message, which defaults to
$0. getopts places the next option letter it finds inside variable
vname each time it is invoked. The option letter is prepended with
a + when arg begins with a +. The index of the next arg is stored
in OPTIND. The option argument, if any, gets stored in OPTARG. A
leading : in optstring causes getopts to store the letter of an
invalid option in OPTARG, and to set vname to ? for an unknown
option and to : when a required option argument is missing.
Otherwise, getopts prints an error message. The exit status is
non-zero when there are no more options. There is no way to
specify any of the options :, +, -, ?, [, and ]. The option # can
only be specified as the first option.

hist [-e ename] [-nlr] [first [last]]
hist -s [old=new] [command]
In the first form, a range of commands from first to last is
selected from the last HISTSIZE commands that were typed at the
terminal. The arguments first and last can be specified as a
number or as a string. A string is used to locate the most recent
command starting with the specified string. A negative number is
used as an offset to the current command number. If the -l option
is selected, the commands are listed on standard output.
Otherwise, the editor program ename is invoked on a file containing
these keyboard commands. If ename is not supplied, then the value
of the variable HISTEDIT is used. If HISTEDIT is not set, then
FCEDIT (default /bin/ed) is used as the editor. When editing is
complete, the edited command(s) is executed if the changes have
been saved. If last is not specified, then it is set to first. If
first is not specified, the default is the previous command for
editing and -16 for listing. The option -r reverses the order of
the commands and the option -n suppresses command numbers when
listing. In the second form, command is interpreted as first
described in this section and defaults to the last command
executed. The resulting command is executed after the optional
substitution old=new is performed.

jobs -lnp [job ...]
Lists information about each specified job, or all active jobs if
job is omitted. The -l option lists process ids in addition to the
normal information. The -n option only displays jobs that have
stopped or exited since last notified. The -p option causes only
the process group to be listed. See Jobs for a description of the
format of job.

kill [-s signame] job ...
kill [-n signum] job ...
kill -Ll [sig ...]
Sends either the TERM (terminate) signal or the specified signal to
the specified jobs or processes. Signals are either specified by
number with the -n option or by name with the -s option (as
specified in <signal.h>, stripped of the prefix `SIG' with the
exception that SIGCLD is named CHLD). For backwards compatibility,
the n and s can be omitted and the number or name placed
immediately after the -. If the signal being sent is TERM
(terminate) or HUP (hang up), then the job or process is sent a
CONT (continue) signal if it is stopped. The argument job can be
the process id of a process that is not a member of one of the
active jobs. See Jobs for a description of the format of job. In
the third form, kill -l or kill -L, if sig is not specified, the
signal names are listed. The -l option lists only the signal names
whereas -L lists each signal name and corresponding number.
Otherwise, for each sig that is a name, the corresponding signal
number is listed. For each sig that is a number, the signal name
corresponding to the least significant 8 bits of sig is listed.

let [arg ...]
Each arg is a separate arithmetic expression to be evaluated. let
only recognizes octal constants starting with 0 when the set option
letoctal is on. See the Arithmetic Evaluation section of this
manual page for a description of arithmetic expression evaluation.
The exit status is 0 if the value of the last expression is
non-zero, and 1 otherwise.

+ newgrp [arg ...]
Equivalent to exec /bin/newgrp arg ...

print [-CRenprsv] [-u unit] [-f format] [arg ...]
With no options or with option - or --, each arg is printed on
standard output. The -f option causes the arguments to be printed
as described by printf. In this case, any -e, -n, -r, or -R
options are ignored. Otherwise, unless the -R or -r options are
specified, the following escape conventions are applied:

\a Alert character (ASCII 007)

\b Backspace character (ASCII 010)

\c Causes print to end without processing more arguments and
not adding a NEWLINE

\f Form-feed character (ASCII 014)

\n NEWLINE character (ASCII 012)

\r RETURN character (ASCII 015)

\t TAB character (ASCII 011)

\v Vertical TAB character (ASCII 013)

\E Escape character (ASCII 033)

\\ Backslash character \

\0x Character defined by the 1, 2, or 3-digit octal string
specified by x

The -R option prints all subsequent arguments and options other
than -n. The -e causes the escape conventions to be applied. This
is the default behavior. It reverses the effect of an earlier -r.
The -p option causes the arguments to be written onto the pipe of
the process spawned with |& instead of standard output. The -v
option treats each arg as a variable name and writes the value in
the printf %B format. The -C option treats each arg as a variable
name and writes the values in the printf %#B format. The -s option
causes the arguments to be written onto the history file instead of
standard output. The -u option can be used to specify a one digit
file descriptor unit number unit on which the output is placed.
The default is 1. If the option -n is used, no NEWLINE is added to
the output.

printf format [arg ...]
The arguments arg are printed on standard output in accordance with
the ANSI-C formatting rules associated with the format string
format. If the number of arguments exceeds the number of format
specifications, the format string is reused to format remaining
arguments. The following extensions can also be used:

%b A %b format can be used instead of %s to cause escape
sequences in the corresponding arg to be expanded as
described in print.

%B A %B option causes each of the arguments to be treated as
variable names and the binary value of the variables is
printed. This is most useful for variables with an
attribute of b.

%H A %H format can be used instead of %s to cause characters
in arg that are special in HTML and XML to be output as
their entity name. The alternate flag # formats the output
for use as a URI.

%P A %P format can be used instead of %s to cause arg to be
interpreted as an extended regular expression and be
printed as a shell pattern.

%R A %R format can be used instead of %s to cause arg to be
interpreted as a shell pattern and to be printed as an
extended regular expression.

%q A %q format can be used instead of % s to cause the
resulting string to be quoted in a manner than can be input
again to the shell. When q is preceded by the alternative
format specifier, #, the string is quoted in manner
suitable for a field in a .csv format file.

%[(date-format)]T
A %[(date-format)]T format can be used to treat an argument
as a date/time string and to format the date/time according
to the date-format as defined for the date(1) command. For
example, `printf '%(%s)T' now' would print the current time
in UNIX timestamp format (seconds since 00:00:00 UTC,
January 1, 1970).

%Z A %Z format outputs a byte whose value is 0.

%d The precision field of the %d format can be followed by a .
and the output base. In this case, the # flag character
causes base # to be prepended.

# The # flag, when used with the %d format without an output
base, displays the output in powers of 1000 indicated by
one of the following suffixes: k M G T P E, and when used
with the %i format displays the output in powers of 1024
indicated by one of the following suffixes: Ki Mi Gi Ti Pi
Ei.

= The = flag centers the output within the specified field
width.

L The L flag, when used with the %c or %s formats, treats
precision as character width instead of byte count.

, The , flag, when used with the %d or %f formats, separates
groups of digits with the grouping delimiter (`,' in groups
of 3 in the C locale).

pwd [-LP]
Outputs the value of the current working directory. The -L option
is the default. It prints the logical name of the current
directory. If the -P option is specified, all symbolic links are
resolved from the name. The last instance of -L or -P on the
command line determines which method is used.

read [-ACSprsv] [-d delim] [-n n | -N n] [-t timeout] [-u unit]
[vname?prompt] [name ...]

The shell input mechanism. One line is read and is broken up into
fields using the characters in IFS as separators. The escape
character, \, is used to remove any special meaning for the next
character and for line continuation. The -d option causes the read
to continue to the first character of delim rather than NEWLINE.
The -n option causes at most n bytes to read rather a full line but
returns when reading from a slow device as soon as any characters
have been read. The -N option causes exactly n to be read unless
an end-of-file has been encountered or the read times out because
of the -t option. In raw mode, -r, the \ character is not treated
specially. The first field is assigned to the first vname, the
second field to the second vname, etc., with leftover fields
assigned to the last vname. When vname has the binary attribute
and -n or -N is specified, the bytes that are read are stored
directly into the variable. If -v is specified, then the value of
the first vname is used as a default value when reading from a
terminal device. The -A option causes the variable vname to be
unset and each field that is read to be stored in successive
elements of the indexed array vname. The -C option causes the
variable vname to be read as a compound variable. Blanks will be
ignored when finding the beginning open parenthesis. The -S option
causes the line to be treated like a record in a .csv format file
so that double quotes can be used to allow the delimiter character
and the new-line character to appear within a field. The -p option
causes the input line to be taken from the input pipe of a process
spawned by the shell using |&. If the -s option is present, the
input is saved as a command in the history file. The option -u can
be used to specify a one digit file descriptor unit unit to read
from. The file descriptor can be opened with the exec special
built-in command. The default value of unit n is 0. The option -t
is used to specify a time out in seconds when reading from a
terminal or pipe. If vname is omitted, then REPLY is used as the
default vname. An end-of-file with the -p option causes cleanup
for this process so that another can be spawned. If the first
argument contains a ?, the remainder of this word is used as a
prompt on standard error when the shell is interactive. The exit
status is 0 unless an end-of-file is encountered or read has timed
out.

++ readonly [-p] [vname[=value]] ...
If vname is not specified, the names and values of each variable
with the read-only attribute is printed with the values quoted in a
manner that allows them to be input again. The -p option causes
the word readonly to be inserted before each one. Otherwise, the
specified vnames are marked readonly and these names cannot be
changed by subsequent assignment.

+ return [n]
Causes a shell function or script to return to the invoking script
with the exit status specified by n. The value is the least
significant 8 bits of the specified status. If n is omitted, then
the return status is that of the last command executed. If return
is invoked while not in a function or a script, then it behaves the
same as exit.

+ set [+-BCGabefhkmnoprstuvx] [+-o [option]] ... [+-A vname] [arg ...]
The set command supports the following options:

-a All subsequent variables that are defined are automatically
exported.

-A Array assignment. Unset the variable vname and assign
values sequentially from the arg list. If +A is used, the
variable vname is not unset first.

-b Prints job completion messages as soon as a background job
changes state rather than waiting for the next prompt.

-B Enable brace pattern field generation. This is the default
behavior.

-C Prevents redirection (>) from truncating existing files.
Files that are created are opened with the O_EXCL mode.
Requires >| to truncate a file when turned on.

-e Unless contained in a || or && command, or the command
following an if, while or until command or in the pipeline
following !, if a command has a non-zero exit status,
execute the ERR trap, if set, and exit. This mode is
disabled while reading profiles.

-f Disables file name generation.

-G Causes the pattern ** by itself to match files and zero or
more directories and subdirectories when used for file name
generation. If followed by a / only directories and
subdirectories are matched.

-h Each command becomes a tracked alias when first
encountered.

-k Obsolete. All variable assignment arguments are placed in
the environment for a command, not just those that precede
the command name.

-m Background jobs run in a separate process group and a line
prints upon completion. The exit status of background jobs
is reported in a completion message. On systems with job
control, this option is turned on automatically for
interactive shells.

-n Read commands and check them for syntax errors, but do not
execute them. Ignored for interactive shells.

-o If no option name is supplied, the list of options and
their current settings are written to standard output.
When invoked with a +, the options are written in a format
that can be input again to the shell to restore the
settings. This option can be repeated to enable or disable
multiple options.

The following argument can be one of the following option
names:

allexport Same as -a.

bgnice All background jobs are run at a lower
priority. This is the default mode.

braceexpand Same as -B.

emacs Puts you in an emacs style inline editor for
command entry.

errexit Same as -e.

globstar Same as -G.

gmacs Puts you in a gmacs style inline editor for
command entry.

ignoreeof The shell does not exit on end-of-file. The
command exit must be used.

keyword Same as -k.

letoctal The let command allows octal constants
starting with 0.

markdirs All directory names resulting from file name
generation have a trailing / appended.

monitor Same as -m.

multiline The built-in editors use multiple lines on
the screen for lines that are longer than the
width of the screen. This might not work for
all terminals.

noclobber Same as -C.

noexec Same as -n.

noglob Same as -f.

nolog Do not save function definitions in the
history file.

notify Same as -b.

nounset Same as -u.

pipefail A pipeline does not complete until all
components of the pipeline have completed,
and the return value is the value of the last
non-zero command to fail or zero if no
command has failed.

privileged Same as -p.

showme When enabled, simple commands or pipelines
preceded by a a semicolon (;) is displayed as
if the xtrace option were enabled but is not
executed. Otherwise, the leading ; is
ignored.

trackall Same as -h.

verbose Same as -v.

vi Puts you in insert mode of a vi style inline
editor until you hit the escape character
033. This puts you in control mode. A
return sends the line.

viraw Each character is processed as it is typed in
vi mode.

xtrace Same as -x.

If no option name is supplied, the current options settings
are printed.

-p Disables processing of the $HOME/.profile file and uses the
file /etc/suid_profile instead of the ENV file. This mode
is on whenever the effective uid (gid) is not equal to the
real uid (gid). Turning this off causes the effective uid
and gid to be set to the real uid and gid.

-r Enables the restricted shell. This option cannot be unset
once set.

-s Sort the positional parameters lexicographically.

-t Obsolete. Exit after reading and executing one command.

-u Treat unset parameters as an error when substituting.

-v Print shell input lines as they are read.

-x Print commands and their arguments as they are executed.

-- Do not change any of the options. This is useful in
setting $1 to a value beginning with -. If no arguments
follow this option then the positional parameters are
unset.

As an obsolete feature, if the first arg is - then the -x and -v
options are turned off and the next arg is treated as the first
argument. Using + rather than - causes these options to be turned
off. These options can also be used upon invocation of the shell.
The current set of options can be found in $-. Unless -A is
specified, the remaining arguments are positional parameters and
are assigned, in order, to $1 $2 .... If no arguments are
specified, then the names and values of all variables are printed
on the standard output.

+ shift [n]
The positional parameters from $n+1 are renamed $1 ..., the default
n is 1. The parameter n can be any arithmetic expression that
evaluates to a non-negative number less than or equal to $#.

sleep seconds
Suspends execution for the number of decimal seconds or fractions
of a second specified by seconds.

+ trap [-p] [action] [sig] ...
The -p option causes the trap action associated with each trap as
specified by the arguments to be printed with appropriate quoting.
Otherwise, action is processed as if it were an argument to eval
when the shell receives signal(s) sig. Each sig can be specified
as a number or as the name of the signal. Trap commands are
executed in order of signal number. Any attempt to set a trap on a
signal that was ignored on entry to the current shell is
ineffective. If action is omitted and the first sig is a number,
or if action is -, then the trap(s) for each sig are reset to their
original values. If action is the null string then this signal is
ignored by the shell and by the commands it invokes. If sig is ERR
then action is executed whenever a command has a non-zero exit
status. If sig is DEBUG then action is executed before each
command. The variable .sh.command contains the contents of the
current command line when action is running. If sig is 0 or EXIT
and the trap statement is executed inside the body of a function
defined with the function name syntax, then the command action is
executed after the function completes. If sig is 0 or EXIT for a
trap set outside any function then the command action is executed
on exit from the shell. If sig is KEYBD, then action is executed
whenever a key is read while in emacs, gmacs, or vi mode. The trap
command with no arguments prints a list of commands associated with
each signal number.

true Does nothing, and exits 0. Used with while for infinite loops.

++ typeset [+-ACHSfblmnprtux] [+-EFLRXZi[n]] [+-M [mapname]]
[-T [tname=(assign_list)]] [-h str] [-a [type]] [vname[=value]]

Sets attributes and values for shell variables and functions. When
invoked inside a function defined with the function name syntax, a
new instance of the variable vname is created, and the variable's
value and type are restored when the function completes.

Using + rather than - causes these options to be turned off. If no
vname arguments are specified, a list of vnames (and optionally the
values) of the variables is printed. Using + rather than -- keeps
the values from being printed. The -p option causes typeset
followed by the option letters to be printed before each name
rather than the names of the options. If any option other than -p
is specified, only those variables which have all of the specified
options are printed. Otherwise, the vnames and attributes of all
variables that have attributes are printed.

The following list of attributes can be specified:

-a Declares vname to be an indexed array. This is optional
unless except for compound variable assignments.

-A Declares vname to be an associative array. Sub-scripts are
strings rather than arithmetic expressions.

-b The variable can hold any number of bytes of data. The
data can be text or binary. The value is represented by
the base64 encoding of the data. If -Z is also specified,
the size in bytes of the data in the buffer is determined
by the size associated with the -Z. If the base64 string
assigned results in more data, it is truncated. Otherwise,
it is filled with bytes whose value is zero. The printf
format %B can be used to output the actual data in this
buffer instead of the base64 encoding of the data.

-C Causes each vname to be a compound variable. If value
names a compound variable it is copied into vname.
Otherwise, it unsets each vname.

-E Declares vname to be a double precision floating point
number. If n is non-zero, it defines the number of
significant figures that are used when expanding vname.
Otherwise, ten significant figures is used.

-f The names refer to function names rather than variable
names. No assignments can be made and the only other valid
options are -t, -u, and -x. The -t option turns on
execution tracing for this function. The -u option causes
this function to be marked undefined. The FPATH variable
is searched to find the function definition when the
function is referenced. If no options other than -f are
specified, then the function definition is displayed on
standard output. If +f is specified, then a line
containing the function name followed by a shell comment
containing the line number and path name of the file where
this function was defined, if any, is displayed. The names
refer to function names rather than variable names. No
assignments can be made and the only other valid options
are -S, -t, -u and -x. The -S option can be used with
discipline functions defined in a type to indicate that the
function is static. For a static function, the same method
will be used by all instances of that type no matter which
instance references it. In addition, it can only use value
of variables from the original type definition. These
discipline functions cannot be redefined in any type
instance. The -t option turns on execution tracing for
this function. The -u option causes this function to be
marked undefined. The FPATH variable will be searched to
find the function definition when the function is
referenced. If no options other than -f are specified,
then the function definition will be displayed on standard
output. If +f is specified, then a line containing the
function name followed by a shell comment containing the
line number and path name of the file where this function
was defined, if any, is displayed. The exit status can be
used to determine whether the function is defined so that
typeset -f .sh.math.name will return 0 when math function
name is defined and non-zero otherwise.

The -i attribute cannot be specified with -f.

-F Declares vname to be a double precision floating point
number. If n is non-zero, it defines the number of places
after the decimal point that are used when expanding vname.
Otherwise ten places after the decimal point is used.

-h Used within type definitions to add information when
generating information about the sub-variable on the man
page. It is ignored when used outside of a type
definition. When used with -f the information is
associated with the corresponding discipline function.

-H This option provides UNIX to hostname file mapping on non-
UNIX machines.

-i Declares vname to be represented internally as integer.
The right hand side of an assignment is evaluated as an
arithmetic expression when assigning to an integer. If n
is non-zero, it defines the output arithmetic base,
otherwise the output base is ten.

The -i attribute cannot be specified along with -R, -L, -Z,
or -f.

-l Used with -i, -E or -F to indicate long integer, or long
float. Otherwise, all upper-case characters are converted
to lower-case. The upper-case option, -u, is turned off.
Equivalent to -M tolower.

-L Left justify and remove leading blanks from value. If n is
non-zero, it defines the width of the field, otherwise it
is determined by the width of the value of first
assignment. When the variable is assigned to, it is filled
on the right with blanks or truncated, if necessary, to fit
into the field. The -R option is turned off.

The -i attribute cannot be specified with -L.

-m moves or renames the variable. The value is the name of a
variable whose value will be moved to vname. The original
variable will be unset. Cannot be used with any other
options.

-M Use the character mapping mapping such as tolower and
toupper when assigning a value to each of the specified
operands. When mapping is specified and there are not
operands, all variables that use this mapping are written
to standard output. When mapping is omitted and there are
no operands, all mapped variables are written to standard
output.

-n Declares vname to be a reference to the variable whose name
is defined by the value of variable vname. This is usually
used to reference a variable inside a function whose name
has been passed as an argument.

-p The name, attributes and values for the given vname are
written on standard output in a form that can be used as
shell input. If +p is specified, then the values are not
displayed.

-R Right justify and fill with leading blanks. If n is
non-zero, it defines the width of the field, otherwise it
is determined by the width of the value of first
assignment. The field is left filled with blanks or
truncated from the end if the variable is reassigned. The
-L option is turned off.

The -i attribute cannot be specified with -R.

-r The specified vnames are marked read-only and these names
cannot be changed by subsequent assignment.

-S When used within the assign_list of a type definition, it
causes the specified sub-variable to be shared by all
instances of the type. When used inside a function defined
with the function reserved word, the specified variables
will have function static scope. Otherwise, the variable
is unset prior to processing the assignment list.

-t Tags the variables. Tags are user definable and have no
special meaning to the shell.

-T If followed by tname, it creates a type named by tname
using the compound assignment assign_list to tname.
Otherwise, it writes all the type definitions to standard
output.

-u When given along with -i specifies unsigned integer.
Otherwise, all lower-case characters are converted to
upper-case. The lower-case option, -l, is turned off.
Equivalent to -M toupper.

-x The specified vnames are marked for automatic export to the
environment of subsequently-executed commands. Variables
whose names contain a . cannot be exported.

-X Declares vname to be a double precision floating point
number and expands using the %a format of ISO-C99. If n is
non-zero, it defines the number of hex digits after the
radix point that is used when expanding vname. The default
is 10.

-Z Right justify and fill with leading zeros if the first non-
blank character is a digit and the -L option has not been
set. Remove leading zeros if the -L option is also set.
If n is non-zero, it defines the width of the field,
otherwise it is determined by the width of the value of
first assignment.

The -i attribute cannot be specified with -Z.

ulimit [-HSacdfmnpstv] [limit]
Set or display a resource limit. Many systems do not support one
or more of these limits. The limit for a specified resource is set
when limit is specified. The value of limit can be a number in the
unit specified with each resource, or the value unlimited. When
more than one resource is specified, then the limit name and unit
is printed before the value.

If no option is specified, -f is assumed.

The following are the available resource limits:

-a Lists all of the current resource limits.

-c The number of 512-byte blocks on the size of core dumps.

-d The number of Kbytes on the size of the data area.

-f The number of 512-byte blocks on files that can be written
by the current process or by child processes (files of any
size can be read).

-H Specifies a hard limit for the specified resource.

A hard limit cannot be increased once it is set.

If neither the -H nor -S option is specified, the limit
applies to both. The current resource limit is printed
when limit is omitted. In this case, the soft limit is
printed unless -H is specified.

-m The number of Kbytes on the size of physical memory.

-n The number of file descriptors plus 1.

-p The number of 512-byte blocks for pipe buffering.

-s The number of Kbytes on the size of the stack area.

-S Specifies a soft limit for the specified resource.

A soft limit can be increased up to the value of the hard
limit.

If neither the -H nor -S option is specified, the limit
applies to both. The current resource limit is printed
when limit is omitted. In this case, the soft limit is
printed unless -H is specified.

-t The number of CPU seconds to be used by each process.

-v The number of Kbytes for virtual memory.

umask [-S] [mask]
The user file-creation mask is set to mask. mask can either be an
octal number or a symbolic value as described in chmod(1).

If a symbolic value is specified, the new umask value is the
complement of the result of applying mask to the complement of the
previous umask value. If mask is omitted, the current value of the
mask is printed. The -S option causes the mode to be printed as a
symbolic value. Otherwise, the mask is printed in octal.

See umask(2)

+ unalias [-a] name ...
The aliases specified by the list of names are removed from the
alias list. The -a option causes all the aliases to be unset.

+ unset [-fnv] vname ...
The variables specified by the list of vnames are unassigned, i.e.,
their values and attributes are erased. Read-only variables cannot
be unset. If the -f option is set, then the names refer to
function names. If the -v option is set, then the names refer to
variable names. The -f option overrides -v. If -n is set and name
is a name reference, then name is unset rather than the variable
that it references. The default is equivalent to -v. Unsetting
LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM, SECONDS, TMOUT, and _
removes their special meaning even if they are subsequently
assigned to.

wait [job]
Wait for the specified job and report its termination status. If
job is not specified, then all currently active child processes are
waited for. The exit status from this command is that of the last
process waited for if job is specified; otherwise it is zero. See
Jobs for a description of the format of job.

whence [-afpv] name ...
For each name, indicate how it would be interpreted if used as a
command name. The -v option produces a more verbose report. The
-f option skips the search for functions. The -p option does a
path search for name even if name is an alias, a function, or a
reserved word. The -a option is similar to the -v option but
causes all interpretations of the specified name to be reported.

Invocation

If the shell is invoked by exec(2), and the first character of argument
zero ($0) is -, then the shell is assumed to be a login shell and commands
are read from /etc/profile and then from either .profile in the current
directory or $HOME/.profile, if either file exists. Next, for interactive
shells, commands are read first from /etc/ksh.kshrc, and then from the file
named by performing parameter expansion, command substitution, and
arithmetic substitution on the value of the environment variable ENV, if
the file exists. If the -s option is not present and arg is specified and
a file by the name of arg exists, then it reads and executes this script.
Otherwise, if the first arg does not contain a /, a path search is
performed on the first arg to determine the name of the script to execute.
The script arg must have execute permission and any setuid and setgid
settings are ignored. If the script is not found on the path, arg is
processed as if it named a built-in command or function.

Commands are then read as described, and the following options are
interpreted by the shell when it is invoked:

-c If the -c option is present, then commands are read from the first
arg. Any remaining arguments become positional parameters starting
at 0.

-D A list of all double quoted strings that are preceded by a $ is
printed on standard output and the shell exits. This set of
strings is subject to language translation when the locale is not C
or POSIX. No commands are executed.

-E Reads the file named by the ENV variable or by $HOME/.kshrc if not
defined after the profiles.

-i If the -i option is present or if the shell input and output are
attached to a terminal (as told by tcgetattr(3C))), this shell is
interactive. In this case TERM is ignored (so that kill 0 does not
kill an interactive shell) and INTR is caught and ignored (so that
wait is interruptible). In all cases, QUIT is ignored by the
shell.

-R filename
The -R filename option is used to generate a cross reference
database that can be used by a separate utility to find definitions
and references for variables and commands.

-r If the -r option is present, the shell is a restricted shell.

-s If the -s option is present or if no arguments remain, then
commands are read from the standard input. Shell output, except
for the output of the Special Commands listed, is written to file
descriptor 2.

The remaining options and arguments are described under the set command.
An optional - as the first argument is ignored.

rksh93 Only
rksh93 is used to set up login names and execution environments whose
capabilities are more controlled than those of the standard shell.

The actions of rksh93 are identical to those of ksh93, except that the
following are disallowed:

+o Unsetting the restricted option

+o Changing directory. See cd(1).

+o Setting or unsetting the value or attributes of SHELL, ENV, FPATH,
or PATH

+o Specifying path or command names containing /

+o Redirecting output (>, >, |, >;, <>, and >>).

+o Adding or deleting built-in commands.

+o Using command -p to invoke a command.

These restrictions are enforced after .profile and the ENV files are
interpreted.

When a command to be executed is found to be a shell procedure, rksh93
invokes ksh93 to execute it. Thus, it is possible to provide to the end-
user shell procedures that have access to the full power of the standard
shell, while imposing a limited menu of commands. This scheme assumes that
the end-user does not have write and execute permissions in the same
directory. The net effect of these rules is that the writer of the
.profile has complete control over user actions, by performing guaranteed
setup actions and leaving the user in an appropriate directory (probably
not the login directory). The system administrator often sets up a
directory of commands, for example, /usr/rbin, that can be safely invoked
by rksh93.

USAGE

See largefile(7) for the description of the behavior of ksh93 and rksh93
when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

FILES

/etc/profile
The system initialization file, executed for login shells.

/etc/ksh.kshrc
The system wide startup file, executed for interactive shells.

$HOME/.profile
The personal initialization file, executed for login shells after
/etc/profile.

$HOME/.kshrc
Default personal initialization file, executed after
/etc/ksh.kshrc, for interactive shells when ENV is not set.

/etc/suid-profile
Alternative initialization file, executed instead of the personal
initialization file when the real and effective user or group id do
not match.

/dev/null
NULL device.

EXIT STATUS

The following exit values are returned:

non-zero
Returns non-zero when errors, such as syntax errors, are detected
by the shell.

If the shell is being used non-interactively, then execution of the
shell file is abandoned unless the error occurs inside a sub-shell
in which case the sub-shell is abandoned.

exit-status-of-last-command-executed
Returns the exit status of the last command executed.

Run time errors detected by the shell are reported by printing the
command or function name and the error condition. If the line
number that the error occurred on is greater than one, then the
line number is also printed in square brackets ([]) after the
command or function name.

See the ksh93 exit command for additional details.

INTERFACE STABILITY

The scripting interface is Uncommitted. The environment variables, .paths
feature, and editing modes are Volatile.

SEE ALSO

cat(1), cd(1), chmod(1), cut(1), date(1), echo(1), egrep(1), env(1),
fgrep(1), grep(1), login(1), newgrp(1), paste(1), perl(1), printf(1),
stty(1), test(1), umask(1), vi(1), dup(2), exec(2), fork(2), ioctl(2),
lseek(2), pathconf(2), pipe(2), ulimit(2), umask(2), rand(3C), sysconf(3C),
tcgetattr(3C), wait(3C), a.out(5), profile(5), attributes(7), environ(7),
largefile(7), standards(7)


Bolsky, Morris I. and Korn, David G., The New KornShell Command and
Programming Language, Prentice Hall, 1995..

POSIX-Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC 9945-2,
IEEE, 1993..

NOTES

ksh93 scripts should choose shell function names outside the namespace used
by reserved keywords of the ISO C99, C++ and JAVA languages to avoid
collisions with future enhancements to ksh93.

If a command is executed, and then a command with the same name is
installed in a directory in the search path before the directory where the
original command was found, the shell continues to exec the original
command. Use the -t option of the alias command to correct this situation.

Some very old shell scripts contain a caret (^) as a synonym for the pipe
character (|).

Using the hist built-in command within a compound command causes the whole
command to disappear from the history file.

The built-in command . file reads the whole file before any commands are
executed. alias and unalias commands in the file do not apply to any
commands defined in the file.

Traps are not processed while a job is waiting for a foreground process.
Thus, a trap on CHLD is not executed until the foreground job terminates.

It is a good idea to leave a space after the comma operator in arithmetic
expressions to prevent the comma from being interpreted as the decimal
point character in certain locales.

There might be some restrictions on creating a .paths file which is
portable across other operating systems.

If the system supports the 64-bit instruction set, /bin/ksh93 executes the
64-bit version of ksh93.

illumos March 8, 2021 illumos