getopt(1)

getopt -- parse command options

Synopsis

set -- `getopt optstring $*`

Description

The getopts(1) command supersedes getopt. See the ``Notices'' section for more information.

getopt is used to break up options in command lines for easy parsing by shell procedures and to check for valid options. It recognizes supplementary code set characters in the argument given to optstring according to the locale specified in the LC_CTYPE environment variable (see LANG on environ(5)).

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 that 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 recognizes it; otherwise, getopt generates it; in either case, getopt places 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.

Files

/usr/lib/locale/locale/LC_MESSAGES/uxcore: language-specific message file (See LANG on environ(5).)

Diagnostics

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

Usage

Reset OPTIND to 1 when rescanning the options.

getopt does not support the part of Rule 8 of the command syntax standard (see intro(1)) that permits groups of option-arguments following an option to be separated by white space and quoted. For example,

cmd -a -b -o "xxx z yy" file

is not handled correctly. To correct this deficiency, use the getopts command instead of getopt.

If an option that takes an option-argument is followed by a value that is the same as an option listed in optstring (referring to the earlier ``Examples'' section, but using the following command line: cmd -o -a file), getopt always treats -a as an option-argument to -o; it never recognizes -a as an option. For this case, the for loop in the example shifts past the file argument.

Examples

The following code fragment shows how you might process the arguments for a command that can take the options a or b, as well as the option o that 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 accepts 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

Notices

Future directions

getopt will not be supported in the next major release. For this release a conversion tool has been provided, getoptcvt. For more information about getopts and getoptcvt, see getopts(1).

References

getopt(3C), getopts(1), sh(1)