Getopt::Long::Configure ("bundling_values"); my $myOpt = 0; GetOptions('s=i'=> \$myOpt); print "bundling_values\n"; print "$myOpt\n\n"; $ test.pl -S1 Unknown option: S1 bundling_values 0 $ test.pl -s1 bundling_values 1 #### Getopt::Long::Configure ("bundling_values"); my $myOpt = 0; GetOptions('S=i'=> \$myOpt); print "bundling_values\n"; print"$myOpt\n\n"; $ test.pl -S1 Unknown option: S1 bundling_values 0 $ test.pl -s1 bundling_values 1 #### Getopt::Long::Configure ("bundling_values", "ignorecase_always"); my $myOpt = 0; GetOptions('S=i'=> \$myOpt); print "bundling_values, ignorecase_always\n"; print "$myOpt\n\n"; $ test.pl -S1 bundling_values, ignorecase_always 1 $ test.pl -s1 bundling_values, ignorecase_always 1