#! /usr/bin/perl -w

$i=@ARGV;
if($i!=2 && $i!=1){
	die("Wrong usage!\n");
	exit(1);
	}
process_files(".");

sub process_files{
	my $line;
	my $file;
	my @files;
	opendir(CWD,"$_[0]") or die("Can't open the current dir!\n");
	chdir("$_[0]");
	@files=readdir CWD;
	foreach $file(@files){
		if($file eq "." || $file eq ".."){
			next;
			}
		if(-T $file){
			open(RF,"+<$file") or die("Can't open file: $file!\n");
			$j=1;
			if($i==1){
				while ($line=<RF>) {
					if(index($line,$ARGV[0])>=0){
						print "$file: $j: $line\n";
						}
					$j++;
					}
				}
			if($i==2){
				while($line=<RF>){
					if(($r=index($line,$ARGV[0]))>=0){
						substr($line,$r,length($ARGV[0]))=$ARGV[1];
						print RF $line;
						print "$file: $j: $line\n";
						}
					$j++;
					}
				}
			close(RF);
			}
		if(-d $file){
			process_files($file);#recursion
			}
		}
	chdir("..");
	closedir(CWD);
	}