#!/usr/bin/perl -w
use strict;
use IO::File;

my $verbose = 1;

my @fh;
while (my $name = shift @ARGV) {
  my $file = new IO::File;
  print "Opening $name\n" if $verbose;
  open ($file,$name);
  push @fh, $file;
}

my $n = 0;
READ: while (++$n) {
  my @filelines;
  for my $file (@fh) {
    my $line = <$file> || last READ;
    push @filelines, $line;
  }

  # Now @filelines contains the nth line from each file
  # so do whatever printing you want with it.  I'm going
  # to print out the first word on each line:

  print "$n = " if $verbose;
  print +(join " : ", map {chomp;(split /\s+/, $_, 2)[0]} @filelines),"\n";
}