MirBSD manpage: getopt(1)

GETOPT(1)                    BSD Reference Manual                    GETOPT(1)

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(3)); 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 whitespace. The special option "--" 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 option is preceded by a "-"
     and in its own shell argument; each option argument is also in its own
     shell argument.

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.

           # make the errorlevel test in the two lines below work with mksh
           set -o sh
           set -- `getopt abo: $*`
           if test $? != 0
           then
                   echo 'Usage: ...'
                   exit 2
           fi
           for i
           do
                   case "$i"
                   in
                           -a|-b)
                                   flag=$i; 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.

     Please do not use getopt in new scripts, use the getopts builtin in
     mksh(1) instead. See also the CAVEATS below for more reasons.

CAVEATS

     The return value of set -- `getopt abo: $*` will be 0 in POSIX-conformant
     shells, such as mksh(1). Only the Bourne shell and AT&T UNIX ksh88 have
     the historic behaviour of returning the exit code of getopt there.

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.

MirBSD #10-current              June 21, 1993                                1