#!/usr/bin/perl

# start at the top

if($#ARGV<1)
{
   print "Usage: replace <old-string> <new-string>\n";
   exit(-1); 
}


$newbuff=pop(@ARGV);
$oldbuff=pop(@ARGV);

&dodir(".",0,$oldbuff,$newbuff);

sub dodir
{
    local($dir,$nlink,$old,$new)=@_;
    local($dev,$ino,$mode,$subcount);

    # at the top level, we need to find nlink ourselves

    ($dev,$ino,$mode,$nlinks)=stat('.') unless $nlink;
    
    # get the list of files in the current directory
    
    opendir(DIR,'.');
    local(@filenames)=readdir(DIR);
    closedir(DIR);

    if($nlinks==2)   # this dir has no subdirs.
    {
	for(@filenames)
	{
	    next if $_ eq '.';
	    next if $_ eq '..';
	    next if /^\./;
	    print "$dir/$_\n";
	    if(!-d)
	    {
		&replace($_,$old,$new);
	    }
	}
    }
    else             # this dir has subdirs.  
    {
	$subcount=$nlinks-2;
	for(@filenames)
	{
	    next if $_ eq '.';
	    next if $_ eq '..';
	    next if /^\./;
	    $name="$dir/$_";
	    print "$name\n";
	    if(!-d)
	    {
	        &replace($_,$old,$new);
	    }
	    next if $subcount==0;       #seen all the subdirs?
	    
	    # get link count and  check for directories...

	    ($dev,$ino,$mode,$nlink)=stat($_);
	    
	    next unless -d _;
	    
	    # it is really a directory, so do it recursively

	    chdir $_ || die "can't cd to $name";
	    &dodir($name,$nlinks,$old,$new);
	    chdir '..';
	    --$subcount;
	}
    }
}

sub replace
{
    local($fil,$old,$new)=@_;
    open(handle,"<$fil");
    open(h2,">$fil.tmp");
    local($count);
    
    $count=0;

    while(<handle>)
    {
	if(/$old/)
	{
	    $count++;
	}
	s/$old/$new/;
	print h2; 
    }

    print "   $count occurences found.\n";
    
    rename("$fil.tmp", $fil);
}