For one, that is a useless use of cat, for another, why use -n when you just want to print your lines anyway? That's what -p is for. You can also put -i to good use here to edit the file inplace, as well as supply a suffix for a backup copy to be kept. perl -i.bak -pe 's/escaped_old_ip/new_ip/g' bigfile Details are available in said manpage. :^)

Makeshifts last the longest.