#!/usr/bin/perl

use strict;

if($ARGV[0] eq "" || $ARGV[1] eq "" || $ARGV[2] eq "") {
    print "Usage: replace.pl [search] [replace] [target dir]\n";
    exit();
}

my @files = <$ARGV[2]/*>;

foreach my $file (@files) {
    
    open(READFILE,"<$file");
    my(@lines) = <READFILE>; 
    close(READFILE);
    
    open(WRITEFILE,">$file");
    
    foreach my $line (@lines) {
	$line =~ s/$ARGV[0]/$ARGV[1]/g;
	print WRITEFILE $line;
    }
    
    close(WRITEFILE);
    
}