hostify: try to translate everything that looks like IP addresses

hostify.pl

#!/usr/bin/perl
# hostify: try to translate everything that looks like IP addresses
# into hostnames. Leave them alone if DNS doesn't resolve them.

# echo "Please tip your 127.0.0.1 well." |hostify
# Please tip your localhost well.

use Socket;

sub host { return gethostbyaddr(inet_aton($_[0]), AF_INET) // $_[0]}

while(<>){
    # s/(\d+\.\d+\.\d+\.\d+)/host $1/ge;
    s/((\b25[0-5]|\b2[0-4][0-9]|\b[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3})/host $1/ge;
    print $_;
}

Might be able to use GNU sed s///e to do something like this without perl, see https://stackoverflow.com/questions/39349032/sed-replace-with-the-output-of-a-bash-command-using-capture-group-as-argument