NAME

getopt − parse command options

SYNOPSIS

set −− `getopt optstring $∗`

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 shell’s positional parameters ($1 $2 ...) 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. 

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.

Version 2.4  —  May 08, 1986