GETOPT(1)                  OpenBSD Reference Manual                  GETOPT(1)

NAME
     getopt - parse command options

SYNOPSIS
     args=`getopt optstring $*`; set -- $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(3)); if a letter is fol-
     lowed by a colon, the option is expected to have an argument which may or
     may not be separated from it by whitespace.  However, if a letter is fol-
     lowed by two colons, the argument is optional and may not be separated by
     whitespace - this is an extension not covered by POSIX.  The special op-
     tion `--' is used to delimit the end of the options.  getopt will place
     `--' in the arguments at the end of the options, or recognize it if used
     explicitly.  The shell arguments ($1, $2, ...) are reset so that each op-
     tion is preceded by a `-' and in its own shell argument; each option ar-
     gument is also in its own shell argument.

     Note that the construction set -- `getopt optstring $*` is not recommend-
     ed, as the exit value from ``set'' will prevent the exit value from
     getopt from being determined.

EXAMPLES
     The following code fragment shows how one might process the arguments for
     a command that can take the options -a and -b, and the option -o, which
     requires an argument.

           args=`getopt abo: $*`
           if [ $? -ne 0 ]
           then
                   echo 'Usage: ...'
                   exit 2
           fi
           set -- $args
           while [ $# -ge 0 ]
           do
                   case "$1"
                   in
                           -a|-b)
                                   flag="$1"; shift;;
                           -o)
                                   oarg="$2"; shift; shift;;
                           --)
                                   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

DIAGNOSTICS
     getopt prints an error message on the standard error output when it en-
     counters an option letter not included in [optstring].

SEE ALSO
     sh(1), getopt(3)

HISTORY
     Written by Henry Spencer, working from a Bell Labs manual page.  Behavior
     believed identical to the Bell version.

BUGS
     Whatever getopt(3) has.

     Arguments containing whitespace or embedded shell metacharacters general-
     ly will not survive intact; this looks easy to fix but isn't.

     The error message for an invalid option is identified as coming from
     getopt rather than from the shell procedure containing the invocation of
     getopt; this again is hard to fix.

     The precise best way to use the set command to set the arguments without
     disrupting the value(s) of shell options varies from one shell version to
     another.

OpenBSD 4.7                     April 12, 2009                               2
