Make msm a flag... 
#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long; 
 
my $string = 'string';
my $length = 'length';
my $msm    = 'msm';

my $result = GetOptions ('des=s' => \$string,
                         'a=s'   => \$string,
                         'd=s'   => \$string,
                         'r=i'   => \$length, 
                         'v=s'   => \$string,
                         'msm'   => \$msm);

[download]
Or simply my $msm;

In reply to Re^3: Syntax errors in setting path.. by Khen1950fx
in thread Syntax errors in setting path.. by Anonymous Monk

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