small letters
You want to change all capital letters into small letters. But then you want to change the first letter of a word into a capital letter. Your content is stored in r1.txt. The result of the script is stored in r2.txt
open (ERSTE, "r1.txt") || die "file not found\n"; @urls = <ERSTE>; close (ERSTE); open (OUTFILE, ">>r2.txt"); for(@urls) { $_ =~ tr/A-Z/a-z/; # change all in small letters $_ = "\u$_"; # change the first into big letters print OUTFILE $_,; $i++; } close (OUTFILE);