Hi, there is a simple solution:

I have the "Programming with perl-Modules" from Patwardhan and Irving (year 1997) where this information is not present...

#!/usr/bin/perl -w
 
use strict;
use Getopt::Long;
 
# If it comes to parallelizing, How many processes do we allow to star
+t
# default is amount of CPUs on that system. May be overridden by comma
+ndline
my $cpu = &num_cpus;
 
my $goback = GetOptions('cpu=i', \$cpu,
           'c=i',   \$cpu,
           'help',  \&cmdline_usage,
           'h',     \&cmdline_usage);
 
print "Number of CPUs here: $cpu\n";
print "Goback was: $goback\n";
 
 
# {{{ get the number of CPUs on that system
#     returns: number of CPUs or 1 if no /proc/cpuinfo was found
sub num_cpus {
    my $num_cpus = 0;
    my $infofile = '/proc/cpuinfo';
 
    if($^O eq 'linux') {         # Yes this is Linux we're running on
        if(-e $infofile) {       # and cpuinfo exists
            open FILE, $infofile;
            while(<FILE>) {
                $num_cpus++ if(/processor/);
            }
            close FILE;
        }
    } # elsif ... your favourite OS detection routine here
 
    # If this is not a known OS we're running on ($num_cpus is then 0)
    # so better be careful and assume 1 CPU
    return $num_cpus || 1;
}
# }}}
[download]

now this gives ok results *most* of the cases, but if you have commandline parameters separatedly, GetOpt silently ignores them:

rj@proxima:~ > pxp.pl -cpu 1
Number of CPUs here: 1
Goback was: 1

=> Ok

rj@proxima:~ > pxp.pl -cpu
Option cpu requires an argument
Number of CPUs here: 2
Goback was:

=> Ok

rj@proxima:~ > pxp.pl -cpu 1 -h=1
Option h does not take an argument
Number of CPUs here: 1
Goback was:

=> Ok

rj@proxima:~ > pxp.pl -cpu 1 -h 1
Usage:
 
-c, --cpu        set the number of CPUs (define parallelization)
-h, --help       print this usage information
Number of CPUs here: 1
Goback was: 1

=> IMHO not Ok

Ciao

Update: The last case definitedly is not ok according to 1211. Iīm citing:

If the option specifier is ``one:i'' (i.e. takes an optional integer argument), then the
  following situations are handled: 

     -one -two            -> $opt_one = '', -two is next option
     -one -2              -> $opt_one = -2

Now that means it WOULD have been ok if I declared h as h:i, but I havenīt.