#!/usr/bin/perl -w
use strict;

my $regexp = $ARGV[0] || die "\nREQUIRES COMMAND-LINE ARGUMENT\n";
my $dir;
if (defined($ARGV[1])) {$dir = $ARGV[1]}
else {$dir = `pwd`}
chomp $dir;

print "\"$regexp\" in $dir/*.pl:\n";

my (%N_index, @files);

opendir(DIR, $dir) || die "can't open $dir";
@files = readdir(DIR);
closedir(DIR);

foreach my $pl (@files) {
        if ($pl =~ /\.pl$/) {
                my $content;
                open (PL, "<$dir/$pl") || die "can't open $dir/$pl"; 
#while (<PL>) {
                $content = do {local $/; <PL>};
#} that was the deleted "while loop"
                close (PL); my $N; 
                if ($content =~ /$regexp/) {
                        $_=$content;
                        $N =()= /$regexp/g;
                        $N_index{$pl}=$N;
                }   
        }   
}

my @rank = sort {$N_index{$b} <=> $N_index{$a}} keys %N_index;
foreach (@rank) {print "\t$N_index{$_} -- $_\n";}
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