in reply to Re^2: How to get only files ending with a ,<word>
in thread How to get only files ending with a ,<word>

Then something like: 
my @comma_extensions = map { /,(\w+)$/ ? $1 : () } @files;

[download]
will produce what you want.
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In Section Seekers of Perl Wisdom