'\" te

.\" Copyright (c) 1982-2007 AT&T Knowledge Ventures

.\" To view license terms, see http://www.opensource.org/licenses/cpl1.0.txt

.\" Portions Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.

.TH ksh 1 "4 Jan 2012" "SunOS 5.11" "User Commands"

.SH NAME

ksh, ksh93, rksh \- Korn Shell, a standard and restricted command and programming language

.SH SYNOPSIS

.LP

.nf

\fBksh\fR [\fB\(+-abcefhikmnoprstuvxBCD\fR] [\fB-R\fR \fIfile\fR] [ \fB\(+-o\fR \fIoption\fR] ...

       [-] [\fIarg\fR ...]

.fi

.LP

.nf

\fBrksh\fR [\fB\(+-abcefhikmnoprstuvxBCD\fR] [\fB-R\fR \fIfile\fR] [\fB\(+-o\fR \fIoption\fR] ...

       [-] [\fIarg\fR ...]

.fi

.SH DESCRIPTION

.sp

.LP

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

.sp

.LP

See \fBInvocation\fR for the meaning of arguments to the shell.

.SS "Definitions"

.sp

.LP

A \fImetacharacter\fR is defined as one of the following characters:

.sp

.in +2

.nf

; & ( ) | < > NEWLINE SPACE TAB

.fi

.in -2

.sp

.sp

.LP

A \fIblank\fR is a \fBTAB\fR or a \fBSPACE\fR. 

.sp

.LP

An \fIidentifier\fR is a sequence of letters, digits, or underscores starting with a letter or underscore. Identifiers are used as components of \fIvariable names\fR. 

.sp

.LP

A \fIvname\fR is a sequence of one or more identifiers separated by a period (\fB\&.\fR) and optionally preceded by a period (\fB\&.\fR). \fIvnames\fR are used as function and variable names. 

.sp

.LP

A \fIword\fR is a sequence of \fIcharacters\fR from the character set defined by the current locale, excluding non-quoted \fImetacharacters\fR.

.sp

.LP

A \fIcommand\fR 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 \fBExecution\fR) 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.

.SS "Commands"

.sp

.LP

A \fIsimple-command\fR is a list of variable assignments (see \fBVariable Assignments\fR) or a sequence of \fIblank\fR-separated words which can be preceded by a list of variable assignments. See the \fBEnvironment\fR section of this manual page.

.sp

.LP

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 \fBexec\fR(2). The \fIvalue\fR of a simple-command is its exit status. If it terminates normally, its value is \fB0\fR-\fB255\fR. If it terminates abnormally, its value is \fB256+\fR\fIsignum\fR. The name of the signal corresponding to the exit status can be obtained by way of the \fB-l\fR option of the kill built-in utility. 

.sp

.LP

A \fIpipeline\fR is a sequence of one or more commands separated by \fB|\fR. The standard output of each command but the last is connected by a \fBpipe\fR(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 \fBpipefail\fR option is enabled. Each pipeline can be preceded by the reserved word\fB!\fR. This causes the exit status of the pipeline to become \fB0\fR if the exit status of the last command is \fBnon-zero\fR, and \fB1\fR if the exit status of the last command is \fB0\fR.

.sp

.LP

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

.sp

.LP

A semicolon (\fB;\fR) causes sequential execution of the preceding pipeline. An ampersand (\fB&\fR) causes asynchronous execution of the preceding pipeline, that is, the shell does \fInot\fR wait for that pipeline to finish. The symbol \fB|&\fR 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 \fB<&\fR and \fB>&\fR with \fBarg p\fR to commands and by using \fB-p\fR option of the built-in commands \fBread\fR and \fBprint\fR. The symbol \fB&&\fR (\fB||\fR) causes the \fIlist\fR following it to be executed only if the preceding pipeline returns a zero (\fBnon-zero\fR) value. One or more NEWLINEs can appear in a \fIlist\fR instead of a semicolon, to delimit a command. The first \fIitem\fR of the first \fIpipeline\fR of a \fIlist\fR that is a simple command not beginning with a redirection, and not occurring within a \fBwhile\fR, \fBuntil\fR, or \fBif\fR \fIlist\fR , can be preceded by a semicolon. This semicolon is ignored unless the \fBshowme\fR option is enabled as described with the \fBset\fR built-in.

.sp

.LP

A \fIcommand\fR 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.

.sp

.ne 2

.mk

.na

\fB\fBfor\fR \fIvname\fR \fB[ in\fR \fIword\fR \fB\&... ] ;do\fR \fIlist\fR \fB;done\fR\fR

.ad

.sp .6

.RS 4n

Each time a \fBfor\fR command is executed, \fIvname\fR is set to the next \fIword\fR taken from the \fBin\fR \fIword\fR list. If \fBin\fR \fIword ...\fR is omitted, the \fBfor\fR command executes the \fBdo\fR \fIlist\fR once for each positional parameter that is set starting from 1. Execution ends when there are no more words in the list. See \fBParameter Expansion\fR. 

.RE

.sp

.ne 2

.mk

.na

\fB\fB(( [\fR\fIexpr1\fR\fB] ; [\fR\fIexpr2\fR] ; [\fIexpr3\fR\fB] )) ;do\fR \fIlist\fR \fB;done\fR\fR

.ad

.sp .6

.RS 4n

The arithmetic expression \fIexpr1\fR is evaluated first. The arithmetic expression \fIexpr2\fR is repeatedly evaluated until it evaluates to \fBzero\fR and when \fBnon-zero\fR, \fIlist\fR is executed and the arithmetic expression \fIexpr3\fR evaluated. If any expression is omitted, then it behaves as if it evaluated to \fB1\fR. See \fBArithmetic Evaluation\fR.

.RE

.sp

.ne 2

.mk

.na

\fB\fBselect\fR \fIvname\fR [ in \fIword\fR \fB\&... ] ;do\fR \fIlist\fR \fB;done\fR\fR

.ad

.sp .6

.RS 4n

A \fBselect\fR command prints on standard error (file descriptor 2) the set of \fIwords\fR, each preceded by a number. If \fBin\fR \fIword...\fR is omitted, the positional parameters starting from \fB1\fR are used instead. See \fBParameter Expansion\fR. The \fBPS3\fR prompt is printed and a line is read from the standard input. If this line consists of the number of one of the listed \fIword\fRs, then the value of the variable \fIvname\fR is set to the \fIword\fR corresponding to this number. If this line is empty, the selection list is printed again. Otherwise the value of the variable \fIvname\fR is set to \fBnull\fR. The contents of the line read from standard input is saved in the variable \fBREPLY\fR. The \fIlist\fR is executed for each selection until a break or \fBEOF\fR is encountered. If the \fBREPLY\fR variable is set to \fBnull\fR by the execution of \fIlist\fR, the selection list is printed before displaying the \fBPS3\fR prompt for the next selection.

.RE

.sp

.ne 2

.mk

.na

\fB\fBcase\fR \fIword\fR \fBin [ [(]\fR \fIpattern\fR \fB[ |\fR \fIpattern\fR \fB] ... )\fR \fIlist\fR \fB;; ] ... esac\fR\fR

.ad

.sp .6

.RS 4n

A \fBcase\fR command executes the \fIlist\fR associated with the first \fIpattern\fR that matches \fIword\fR. The form of the patterns is the same as that used for file name generation. See \fBFile Name Generation\fR. 

.sp

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

.RE

.sp

.ne 2

.mk

.na

\fB\fBif\fR \fIlist\fR \fB;then\fR \fIlist\fR \fB[ ;elif\fR \fIlist\fR \fB;then\fR \fIlist\fR ] \fB\&... [ ;else\fR \fIlist\fR \fB]\fR \fB;fi\fR\fR

.ad

.sp .6

.RS 4n

The \fIlist\fR following \fBif\fR is executed and, if it returns a \fBzero\fR exit status, the \fIlist\fR following the first \fBthen\fR is executed. Otherwise, the \fIlist\fR following \fBelif\fR is executed, and, if its value is \fBzero\fR, the \fIlist\fR following the next \fBthen\fR is executed. Failing each successive \fBelif\fR \fIlist\fR, the \fBelse\fR \fIlist\fR is executed. If the \fBif\fR \fIlist\fR has \fBnon-zero\fR exit status and there is no \fBelse\fR \fIlist\fR, then the \fBif\fR command returns a \fBzero\fR exit status.

.RE

.sp

.ne 2

.mk

.na

\fB\fBwhile\fR \fIlist\fR \fB;do\fR \fIlist\fR \fB;done\fR\fR

.ad

.br

.na

\fBuntil \fIlist\fR \fB;do\fR \fIlist\fR \fB;done\fR\fR

.ad

.sp .6

.RS 4n

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

.RE

.sp

.ne 2

.mk

.na

\fB\fB((\fR\fIexpression\fR\fB))\fR\fR

.ad

.sp .6

.RS 4n

The \fIexpression\fR is evaluated using the rules for arithmetic evaluation described in this manual page. If the value of the arithmetic expression is \fBnon-zero\fR, the exit status is \fB0\fR. Otherwise the exit status is \fB1\fR. 

.RE

.sp

.ne 2

.mk

.na

\fB\fB(\fR\fIlist\fR\fB;)\fR\fR

.ad

.sp .6

.RS 4n

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.

.sp

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

.RE

.sp

.ne 2

.mk

.na

\fB\fB[[\fR \fIexpression\fR \fB]]\fR\fR

.ad

.sp .6

.RS 4n

Evaluates \fIexpression\fR and returns a \fBzero\fR exit status when \fIexpression\fR is true. See \fBConditional Expressions\fR for a description of \fIexpression\fR.

.RE

.sp

.ne 2

.mk

.na

\fB\fBfunction\fR \fIvarname\fR \fB{\fR \fIlist\fR \fB;}\fR\fR

.ad

.br

.na

\fB\fIvarname\fR \fB() {\fR \fIlist\fR \fB;}\fR\fR

.ad

.sp .6

.RS 4n

Define a function which is referenced by \fIvarname\fR. A function whose \fIvarname\fR contains a \fB\&.\fR is called a discipline function and the portion of the \fIvarname\fR preceding the last \fB\&.\fR must refer to an existing variable. 

.sp

The body of the function is the \fIlist\fR of commands between \fB{\fR and \fB}\fR. A function defined with the function \fIvarname\fR syntax can also be used as an argument to the \fB\&.\fR special built-in command to get the equivalent behavior as if the \fIvarname\fR\fB()\fR syntax were used to define it. See \fBFunctions\fR.

.RE

.sp

.ne 2

.mk

.na

\fB\fBtime [\fR \fIpipeline\fR \fB]\fR\fR

.ad

.sp .6

.RS 4n

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

.RE

.sp

.LP

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

.br

.in +2

\fBcase\fR

.in -2

.br

.in +2

\fBdo\fR

.in -2

.br

.in +2

\fBdone\fR

.in -2

.br

.in +2

\fBelse\fR

.in -2

.br

.in +2

\fBelif\fR

.in -2

.br

.in +2

\fBesac\fR

.in -2

.br

.in +2

\fBfor\fR

.in -2

.br

.in +2

\fBfi\fR

.in -2

.br

.in +2

\fBfunction\fR

.in -2

.br

.in +2

\fBif\fR

.in -2

.br

.in +2

\fBselect\fR

.in -2

.br

.in +2

\fBthen\fR

.in -2

.br

.in +2

\fBtime\fR

.in -2

.br

.in +2

\fBuntil\fR

.in -2

.br

.in +2

\fBwhile\fR

.in -2

.br

.in +2

\fB{ }\fR

.in -2

.br

.in +2

\fB[[ ]]\fR

.in -2

.br

.in +2

\fB!\fR

.in -2

.SS "Variable Assignments"

.sp

.LP

One or more variable assignments can start a simple command or can be arguments to the \fBtypeset\fR, \fBexport\fR, or \fBreadonly\fR special built-in commands. The syntax for an \fIassignment\fR is of the form:

.sp

.ne 2

.mk

.na

\fB\fIvarname\fR\fB=\fR\fIword\fR\fR

.ad

.br

.na

\fB\fIvarname\fR\fB[\fR\fIword\fR\fB]=\fR\fIword\fR\fR

.ad

.sp .6

.RS 4n

No space is permitted between \fIvarname\fR and the \fB=\fR or between \fB=\fR and \fIword\fR. 

.RE

.sp

.ne 2

.mk

.na

\fB\fIvarname\fR\fB=(\fR\fIassignlist\fR\fB)\fR\fR

.ad

.sp .6

.RS 4n

No space is permitted between \fIvarname\fR and the \fB=\fR. An \fIassignlist\fR can be one of the following:

.sp

.ne 2

.mk

.na

\fB\fIword ...\fR\fR

.ad

.sp .6

.RS 4n

Indexed array assignment.

.RE

.sp

.ne 2

.mk

.na

\fB\fB[\fR\fIword\fR\fB]=\fR\fIword ...\fR\fR

.ad

.sp .6

.RS 4n

Associative array assignment. If prefixed by \fBtypeset\fR \fB-a\fR, creates an indexed array instead.

.RE

.sp

.ne 2

.mk

.na

\fB\fIassignment ...\fR\fR

.ad

.sp .6

.RS 4n

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

.RE

.sp

.ne 2

.mk

.na

\fB\fBtypeset [\fR\fIoptions\fR] \fIassignment\fR \fB\&...\fR\fR

.ad

.sp .6

.RS 4n

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

.RE

In addition, a \fB+=\fR can be used in place of the \fB=\fR to signify adding to or appending to the previous value. When \fB+=\fR is applied to an arithmetic type, \fIword\fR is evaluated as an arithmetic expression and added to the current value. When applied to a string variable, the value defined by \fIword\fR 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. 

.RE

.SS "Comments"

.sp

.LP

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

.SS "Aliasing"

.sp

.LP

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, and \fB=\fR. The replacement string can contain any valid shell script including the metacharacters listed in the \fBCommands\fR 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. 

.sp

.LP

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

.sp

.LP

Aliasing is performed when scripts are read, not while they are executed. For an alias to take effect, the \fBalias\fR 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:

.sp

.in +2

.nf

autoload='typeset -fu'

command='command '

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'

.fi

.in -2

.sp

.SS "Tilde Substitution"

.sp

.LP

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

.sp

.LP

If it does, the word up to a \fB/\fR is checked to see if it matches a user name in the password database. If a match is found, the \fB~\fR 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 \fB~\fR by itself, or in front of a \fB/\fR, is replaced by \fB$HOME\fR. A \fB~\fR followed by a \fB+\fR or \fB-\fR is replaced by the value of \fB$PWD\fR and \fB$OLDPWD\fR respectively.

.sp

.LP

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

.SS "Command Substitution"

.sp

.LP

The standard output from a command enclosed in parentheses preceded by a dollar sign (\fB$\fR) or a pair of grave accents (\fB``\fR) can be used as part or all of a word. Trailing NEWLINEs are removed. In the second (obsolete) form, the string between the quotes is processed for special quoting characters before the command is executed. See \fBQuoting\fR. 

.sp

.LP

The command substitution \fB$(cat file)\fR can be replaced by the equivalent but faster \fB$(<file)\fR. The command substitution \fB$(\fR\fIn\fR\fB<#)\fR expands to the current byte offset for file descriptor \fIn\fR.

.SS "Arithmetic Substitution"

.sp

.LP

An arithmetic expression enclosed in double parentheses preceded by a dollar sign ( \fB$((\fR\fIarithmetic_expression\fR\fB))\fR) is replaced by the value of the arithmetic expression within the double parentheses.

.SS "Process Substitution"

.sp

.LP

Process substitution is only available on versions of the UNIX operating system that support the \fB/dev/fd\fR directory for naming open files. 

.sp

.LP

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

.sp

.LP

For example,

.sp

.in +2

.nf

paste <(cut -f1 \fIfile1\fR) <(cut -f3 \fIfile2\fR) | tee \e

     >(\fIprocess1\fR) >(\fIprocess2\fR)

.fi

.in -2

.sp

.sp

.LP

\fBcut\fRs fields 1 and 3 from the files \fIfile1\fR and \fIfile2\fR respectively, \fBpaste\fRs the results together, and sends it to the processes \fIprocess1\fR and \fIprocess2\fR. It also displays the results to the standard output. The file, which is passed as an argument to the command, is a UNIX \fBpipe\fR(2). Programs that expect to \fBlseek\fR(2) on the file do not work. 

.SS "Parameter Expansion"

.sp

.LP

A parameter is a variable, one or more digits, or any of the characters \fB*\fR, \fB@\fR, \fB#\fR, \fB?\fR, \fB-\fR, \fB$\fR, and \fB!\fR. A variable is denoted by a \fIvname\fR. To create a variable whose \fIvname\fR contains a \fB\&.\fR, a variable whose \fBvname\fR 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 \fBtypeset\fR special built-in command. The attributes supported by the shell are described later with the \fBtypeset\fR special built-in command. Exported variables pass values and attributes to the environment. 

.sp

.LP

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 \fBArithmetic Evaluation\fR), between a \fB[\fR and a \fB]\fR. Use \fBset -A\fR \fIvname value ...\fR to assign values to an indexed array. The value of all subscripts must be in the range of \fB0\fR through \fB1,048,575\fR. Indexed arrays do not need to be declared. Any reference to a variable with a valid subscript is legal and an array is created if necessary. 

.sp

.LP

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

.sp

.LP

Referencing any array without a subscript is equivalent to referencing the array with subscript \fB0\fR.

.sp

.LP

The value of a variable can be assigned by:

.sp

.in +2

.nf

\fIvname\fR=\fIvalue\fR [\fIvname\fR=\fIvalue\fR] ...

.fi

.in -2

.sp

.sp

.LP

or

.sp

.in +2

.nf

\fIvname\fR[\fIsubscript\fR]=\fIvalue\fR [\fIvname\fR[\fIsubscript\fR]=\fIvalue\fR] ...

.fi

.in -2

.sp

.sp

.LP

No space is allowed before or after the \fB=\fR. A \fInameref\fR is a variable that is a reference to another variable. A \fInameref\fR is created with the \fB-n\fR attribute of \fBtypeset\fR. The value of the variable at the time of the \fBtypeset\fR command becomes the variable that is referenced whenever the \fInameref\fR variable is used. The name of a \fInameref\fR cannot contain a dot (\fI\&.\fR). When a variable or function name contains a \fB\&.,\fR and the portion of the name up to the first \fB\&.\fR matches the name of a \fInameref\fR, the variable referred to is obtained by replacing the \fInameref\fR portion with the name of the variable referenced by the \fInameref\fR. If a \fInameref\fR is used as the index of a \fBfor\fR loop, a name reference is established for each item in the list. A \fInameref\fR 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

.sp

.in +2

.nf

 typeset -n var=$1

.fi

.in -2

.sp

.sp

.LP

inside the function causes references and assignments to \fIvar\fR to be references and assignments to the variable whose name has been passed to the function. If either of the floating point attributes, \fB-E\fR, or \fB-F\fR, or the integer attribute, \fB-i\fR, is set for \fIvname\fR, then the \fIvalue\fR is subject to arithmetic evaluation as described in this manual page. Positional parameters, parameters denoted by a number, can be assigned values with the \fBset\fR special built-in command. Parameter \fB$0\fR is set from argument zero when the shell is invoked. The character \fB$\fR is used to introduce substitutable parameters.

.sp

.ne 2

.mk

.na

\fB\fB${\fR\fIparameter\fR\fB}\fR\fR

.ad

.sp .6

.RS 4n

The shell reads all the characters from \fB${\fR to the matching \fB}\fR 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 \fIparameter\fR is followed by a letter, digit, or underscore that is not to be interpreted as part of its name, when the variable name contains a \fB\&.\fR, or when a variable is subscripted. If \fIparameter\fR 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 \fIparameter\fR is \fB*\fR or \fB@\fR, then all the positional parameters, starting with \fB$1\fR, are substituted and separated by a field separator character. If an array \fIvname\fR with subscript \fB*\fR or \fB@\fR is used, then the value for each of the elements is substituted, separated by the first character of the value of \fBIFS\fR.

.RE

.sp

.ne 2

.mk

.na

\fB\fB${#\fR\fIparameter\fR\fB}\fR\fR

.ad

.sp .6

.RS 4n

If \fIparameter\fR is \fB*\fR or \fB@\fR, the number of positional parameters is substituted. Otherwise, the length of the value of the \fIparameter\fR is substituted.

.RE

.sp

.ne 2

.mk

.na

\fB\fB${#\fR\fIvname\fR\fB[*]}\fR\fR

.ad

.br

.na

\fB\fB${#\fR\fIvname\fR\fB[@]}\fR\fR

.ad

.sp .6

.RS 4n

The number of elements in the array \fIvname\fR is substituted.

.RE

.sp

.ne 2

.mk