Simple script to find strings common to all files specified on command line. (the intersection)

intersect.pl

#!/usr/bin/env perl

# Read each file specified on command line and print lines found in all files
#
open(FH,$ARGV[0]); chomp(@isect = <FH>); close(FH);
shift(@ARGV);

while (@ARGV) { 
  ## read each file into an array and strip newlines
  open(FH,$ARGV[0]); chomp(@f = <FH>); close(FH);
  shift(@ARGV);
  @isect = intersection(@isect,@f);
}

print "$_\n" foreach (@isect);

sub intersection {
  (@a, @b) = @_;
  @union = @isect = ();
  %union = %isect = ();
  foreach $e (@a, @b) { $union{$e}++ && $isect{$e}++};
  @isect = keys %isect;
  return (@isect);
}