No, you are not getting close. You don't specify what you want to do, all you do is give 1 example, and the code is so off it's unguessable what you want.

Do you want to repeat every two characters? Then you could just do:

die "No parameters given\n" unless @ARGV;
$ARGV [0] =~ s/(..)/$1$1/g;
print $ARGV [0], "\n";
[download]

If you want to do something else, please be more specific.

Abigail