if (-f $file) {
    open CONF, "<$file";
    my @contents = <CONF>;
    close CONF;

    foreach $content (@contents) {
        my @config = split /-/,$content;
        if ($content =~ /DEFAULT_IN/) {
            $default_in = $config[1];
            chomp($default_in);
        } elsif ($content =~ /DEFAULT_OUT/) {
            $default_out = $config[1];
            chomp($default_out);
        }
    }
}

##</code><code>##

print CONF "DEFAULT_IN-$def_path\nDEFAULT_OUT-$def_path_out\n";

##</code><code>##

if( ($def_path ne $default_in) || ($def_path_out ne $default_out) ) {
    # at least one of the values changed, write both
}