  ### tclGetOpts - getopt NAME `getopt, optind, optindc` - parse command-line options in TCL SYNOPSIS `getopt arglist optstring optret argret` DESCRIPTION `getopt` sets the variable `optret` to the next option letter in `arglist` that matches a letter in `optstring`. `optstring` must contain the option letters the command using `getopt` will recognize; if a letter is followed by a colon, the option is expected to have an argument. The variable `argret` will be set to the option argument, if any. `getopt` sets the global variables `optind` and `optindc` to point to the next option letter in `arglist` to be processed; `optind` holds the index of the option in the list, and `optindc` holds the index of the option letter in the string. When all options have been processed (that is, up to the first non-option argument), `getopt` returns an empty string. The special option `--` may be used to delimit the end of the options; when it is encountered, `optret` will be set to the empty string, and the `--` will be skipped. If `getopt` encounters an option in `arglist` that is not described in `optstring`, or it finds an option with no argument when the option requires one, it sets `optret` to a blank string and `argret` to an error message. `getopt` returns `1` if an option was found, `0` if no more options were found, and `-1` if an error occurred. EXAMPLE The following script accepts the exclusive options `-a` and `-b`, and the option `-o` with an argument.
           #!/usr/local/bin/tclsh

           set opts(a) 0
           set opts(b) 0
           set opts(o) ""

           proc usage {} {
             puts stderr "Usage: $argv0 [ -a | -b ] [ -o <string> ]"
             exit 22
           }

           while { [ set err [ getopt $argv "abo:" opt arg ]] } {
             if { $err < 0 } then {
               puts stderr "$argv0: $arg"
               usage
             } else {
               switch -exact $opt {
                 a {
                   if { $found(b) } then {
                     puts stderr "$argv0: Only one of -a and -b may be specified!"
                     usage
                   } else {
                     set found(a) 1
                   }
                 }
                 b {
                   if { $found(a) } then {
                     puts stderr "$argv0: Only one of -a and -b may be specified!"
                     usage
                   } else {
                     set found(b) 1
                   }
                 }
                 o {
                   set found(o) $optarg
                 }
               }
             }
           }

           set argv [ lrange $argv $optind end ]

           if { $found(a) } then {
             puts stdout "Found option -a"
           }

           if { $found(b) } then {
             puts stdout "Found option -b"
           }

           if { [ string length $found(o) ] } then {
             puts stdout "Found option -o:
           }

           puts -nonewline stdout "The rest of the arguments are: "
           set prefix ""
           foreach arg $argv {
             puts -nonewline stdout "$prefix
             set prefix ", "
           }
           puts stdout ""
SEE ALSO `getopt(3C), typedopts` http://www.waxandwane.com/toolbox/tclGetOpts/ AUTHOR Ross Mohn, RPMohn@panix.com Johnson Earls WARNING Changing the value of the variable `optind`, or calling `getopt` with a different `arglist`, may lead to unexpected results.