getopts(C)                    06 January 1993                     getopts(C)


 Name

    getopts, getoptcvt - parse command options

 Syntax

    getopts optstring name [ arg ... ]

    /usr/lib/getoptcvt [ -b ] file

 Description

    The getopts command is used by shell procedures to parse positional pa-
    rameters and to check for legal options.  It supports all applicable
    rules of the command syntax standard (see Rules 3-10, Intro(C)).  It
    should be used in place of the getopt(C) command.  (See the ``Notes''
    below.)

    This feature is only available in the Bourne (sh) and Korn (ksh) shells.

    optstring must contain the option letters the command using getopts will
    recognize; if a letter is followed by a colon, the option is expected to
    have an argument, or group of arguments, which must be separated from it
    by white space.

    Each time it is invoked, getopts will place the next option in the shell
    variable name and the index of the next argument to be processed in the
    shell variable OPTIND.  Whenever the shell is invoked, OPTIND is initial-
    ized to 1. To process another set of arguments within a script, set
    OPTIND to 1 before invoking getopts.

    When an option requires an option-argument, getopts places it in the
    shell variable OPTARG.

    If an illegal option is encountered, getopts prints a message to standard
    error, and sets the name variable to ``?''.

    When the end of options is encountered, getopts exits with a status of 1.
    The special option ``--'' may be used to delimit the end of the options.

    By default, getopts parses the positional parameters.  If extra arguments
    (arg...) are given on the getopts command line, getopts will parse them
    instead.

    The /usr/lib/getoptcvt command reads the shell script in file, converts
    it to use getopts(C) instead of getopt(C), and writes the results to the
    standard output.

    -b   the results of running /usr/lib/getoptcvt will be portable to ear-
         lier UNIX releases.  /usr/lib/getoptcvt modifies the shell script in
         file so that when the resulting shell script is executed, it deter-
         mines at run time whether to invoke getopts(C) or getopt(C).

    So all new commands will adhere to the command syntax standard described
    in Intro(C), they should use getopts(C) or getopt(S) to parse positional
    parameters and check for options that are legal for that command (see
    ``Notes'' below).

 Examples

    The following fragment of a shell program (named foo) 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 option-argument:

       HELP="foo is the archetypal example program"
       USAGE="foo [[-h] | [[-a | -b] [-o list] [otherargs ... ]]]"

       if [ $# = 0 ]
       then
               echo $USAGE
               exit 1
       fi

       while getopts habo: c
       do
               case $c in
               h)      echo $HELP
                       echo $USAGE
                       exit 2;;
               a | b)  FLAG=$c;;
               o)      OARG=$OPTARG;;
               ?)     echo $USAGE
                       exit 3;;
               esac
       done
       shift `expr $OPTIND - 1`

    The shift command allows the shell program to continue to process any
    other arguments. This example will accept any of the following as
    equivalent:

       foo -a -o "xxx z yy"
       foo -o "xxx z yy" -a
       foo -a -o "xxx z yy" --

 See also

    Intro(C), getopt(S) and sh(C).

 Notes

    Although the following command syntax rule (see Intro(C)) relaxations are
    permitted under the current implementation, they should not be used
    because they may not be supported in future releases of the system.  As
    in the ``Examples'' section above, -a and -o are options to command, with
    option -o requiring an option-argument:

    command -ao xxx file
            (Rule 5 violation:  options with option-arguments must not be
            grouped with other options.)

    command -a -oxxx file
            (Rule 6 violation: there must be white space after an option that
            takes an option-argument.)

    Changing the value of the shell variable OPTIND or parsing different sets
    of arguments may lead to unexpected results.

 Diagnostics

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