NAME

getopt − parse command options

SYNOPSIS

getopt optstring args

DESCRIPTION

Getopt is used to break up options in command lines for easy parsing by shell procedures and to check for legal options.  Optstring is a string of recognized option letters (see getopt(3C)); if a letter is followed by a colon, the option is expected to have an argument which may or may not be separated from it by white space. The special option −− is used to delimit the end of the options.  If it is used explicitly, getopt will recognize it; otherwise, getopt will generate it; in either case, getopt will place it at the end of the options.  The positional parameters ($1 $2 ...) of the shell are reset so that each option is preceded by a − and is in its own positional parameter; each option argument is also parsed into its own positional parameter. 

The most common use of getopt is in the shell’s set command (see the example below).  There, getopt converts the command line to a more easily parsed form.  Getopt writes the modified command line to the standard output. 

EXAMPLE

The following code fragment shows how one might process the arguments for a command that can take the options a or b, as well as the option o, which requires an argument:

set −− `getopt abo: $∗`
if [ $? != 0 ]
then
echo $USAGE
exit 2
fi
for i in $∗
do
case $i in
−a │ −b)FLAG=$i; shift;;
−o)OARG=$2; shift 2;;
−−)shift; break;;
esac
done

This code will accept any of the following as equivalent:

cmd −aoarg file file
cmd −a −o arg file file
cmd −oarg −a file file
cmd −a −oarg −− file file

SEE ALSO

sh(1), getopt(3C). 

DIAGNOSTICS

Getopt prints an error message on the standard error when it encounters an option letter not included in optstring.

INTERNATIONAL SUPPORT

8- and 16-bit data. 

Hewlett-Packard Company  —  Version B.1,  April 12, 1993