getopt Command

Purpose

Parses command line flags and parameters.

Syntax

getopt Format Tokens

Description

The getopt command parses a list of tokens using a format that specifies expected flags and arguments. A flag is a single ASCII letter and when followed by a : (colon) is expected to have an argument that may or may not be separated from it by one or more tabs or spaces. You can include multibyte characters in arguments, but not as a flag letter.

The getopt command completes processing when it has read all tokens or when it encounters the special token -- (double hyphen). The getopt command then outputs the processed flags, a -- (double hyphen), and any remaining tokens.

If a token fails to match a flag, the getopt command writes a message to standard error.

Examples

The getopt command can be used in a skeleton shell script to parse options, as in the following example:

#!/usr/bin/bsh
# parse command line into arguments
set -- `getopt a:bc $*`
# check result of parsing
if [ $? != 0 ]
then
        exit 1
fi
while [ $1 != -- ]
do
        case $1 in
        -a)     # set up the -a flag
                AFLG=1
                AARG=$2
                shift;;
        -b)     # set up the -b flag
                BFLG=1;;
        -c)     # set up the -c flag
                CFLG=1;;
        esac
        shift   # next flag
done
shift   # skip --
# now do the work
.
.
.
 

Note: In the C shell, use the following command to run the getopt command:

set argv=`getopt OptionString $*`

In each of the following examples, the getopt command would process the flags and arguments in the same way:

• -a ARG -b -c
• -a ARG -bc
• -aARG -b -c
• -b -c -a ARG

Files

Related Information

The bsh command, csh command.

The getopt subroutine.

Shells Overview in AIX Version 4.3 System User's Guide: Operating System and Devices.