foreach  (@files)
{
    open(LDATA, "$_") || warn "File does not open: $!\n";
    open(TMP, ">$_.tmp") || warn "File Write problem $_.tmp: $!\n";
    
    while (<LDATA>)
    {
        s/OLD/NEW/gi;
        print TMP $_;
    }
    close(LDATA);
    close(TMP);
    rename("$_.tmp", "$_") or warn "Could not rename '$_.tmp' to '$_': $!\n";
}