#!/usr/bin/perl

FILE: for my $file (glob '*.txt') {
    open my $fh, '<', $file or die "$file: D'Oh! $!\n";
    while (<$fh>) {
        /(?=^(?:(?!green red blue).)*$).*?(green|red|blue)/i;
	do { 
	    print "$file \n";
	    next FILE;
	} if $1;
     }
   }