[perlpetual@joesatch practice]$ perl wwn_final.pl 
Enter 
       a for lowercase and colons.
       b to do it the other way around.
       q to quit a
Enter the wwn or q to quit: 10000000C9ABCDEF
10:00:00:00:c9:ab:cd:ef
Enter the wwn or q to quit: 10:00:00:00:c9:ab:cd:ef
Invalid Length Or Incorrect Format
Enter the wwn or q to quit: 10000000C9ABCDEG
Invalid Length Or Incorrect Format
Enter the wwn or q to quit: 10000000abcdefga
Invalid Length Or Incorrect Format
Enter the wwn or q to quit: 10000000abcdefab
10:00:00:00:ab:cd:ef:ab
Enter the wwn or q to quit: q
Invalid Length Or Incorrect Format
[perlpetual@joesatch practice]$ perl wwn_final.pl 
Enter 
       a for lowercase and colons.
       b to do it the other way around.
       q to quit b
Enter the wwn with : or q to quit: 10:00:00:00:c9:ab:cd:ef
10000000c9abcdef
Enter the wwn with : or q to quit: 10:00:00:00:c9:ab:cd:eg
Invalid Length Or Incorrect Format
Enter the wwn with : or q to quit: 10:00:00:00:c9:ab:cd:e 
Invalid Length Or Incorrect Format
Enter the wwn with : or q to quit: 10000000c9abcdef
Invalid Length Or Incorrect Format
Enter the wwn with : or q to quit: q
Invalid Length Or Incorrect Format
[perlpetual@joesatch practice]$