#!/usr/bin/perl

# http://perlmonks.org/?node_id=1175477

use strict;
use warnings;

while(<DATA>)
  {
  s/^\S+\s+(\d+)computer(\d+).*\K/  $1host$2/;
  print;
  }

__DATA__
1.1.1.1   01computer12   01computer12.abc.com
1.1.1.2   34computer21   34computer21.abc.com