The following scans a list of files (@files) for a
list of words (@words), and prints out the names of 
those files that contain a match: 

   $search = 'while (<>) { study;';
         foreach $word (@words) {
             $search .= "++\$seen{\$ARGV} if /\\b$word\\b/;\n";
         }
         $search .= "}";
         @ARGV = @files;
         undef $/;
         eval $search;               # this screams
         $/ = "\n";          # put back to normal input delimiter
         foreach $file (sort keys(%seen)) {
             print $file, "\n";
         }