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GETOPT(1)               FreeBSD General Commands Manual              GETOPT(1)

NAME
     getopt - parse command options

SYNOPSIS
     args=`getopt optstring $*` ; errcode=$?; 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 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.  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.

           args=`getopt abo: $*`
           # you should not use `getopt abo: "$@"` since that would parse
           # the arguments differently from what the set command below does.
           if [ $? != 0 ]
           then
                   echo 'Usage: ...'
                   exit 2
           fi
           set -- $args
           # You cannot use the set command with a backquoted getopt directly,
           # since the exit code from getopt would be shadowed by those of set,
           # which is zero by definition.
           for i
           do
                   case "$i"
                   in
                           -a|-b)
                                   echo flag $i set; sflags="${i#-}$sflags";
                                   shift;;
                           -o)
                                   echo oarg is "'"$2"'"; oarg="$2"; shift;
                                   shift;;
                           --)
                                   shift; break;;
                   esac
           done
           echo single-char flags: "'"$sflags"'"
           echo oarg is "'"$oarg"'"

     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(3)

DIAGNOSTICS
     Getopt prints an error message on the standard error output and exits
     with status > 0 when it encounters an option letter not included in
     optstring.

HISTORY
     Written by Henry Spencer, working from a Bell Labs manual page.  Behavior
     believed identical to the Bell version.  Example changed in FreeBSD
     version 3.2 and 4.0.

BUGS
     Whatever getopt(3) has.

     Arguments containing white space or embedded shell metacharacters
     generally will not survive intact;  this looks easy to fix but isn't.
     People trying to fix getopt or the example in this manpage should check
     the history of this file in FreeBSD.

     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.

     Each shellscript has to carry complex code to parse arguments halfway
     correcty (like the example presented here). A better getopt-like tool
     would move much of the complexity into the tool and keep the client shell
     scripts simpler.

FreeBSD 11.0-PRERELEASE          April 3, 1999         FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | DIAGNOSTICS | HISTORY | BUGS

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