> perl -wnle "print qq(Files remaining ) . @ARGV; print $seen{$_} .= @ARGV; " file1 file2 file3

##</code><code>##

#!perl -w
use strict;

my %seen;
sub intersect {
    # see perlfaq4
};

my $first_file = shift @ARGV;
my @common = read_file($first_file);
for (@ARGV) {
    @common = intersect( \@common, [ read_file $_ ] );
};

print "$_\n" for @common;