# Top level
my $choice = get_choice();
do_ip_manual() if $choice == 1;
do_ip_fromfile() if $choice == 2;

# Lower level
sub do_ip_manual {
    my ($user, $pass) = get_auth();
    ...
}

# Even lower level
...

##</code><code>##

my $ret = system "`xcopy "C:\\Program Files\\UltraVNC\\*.*" "\\\\$ip\\C\$\\Program Files\\UltraVNC\\*.*" /r/i/c/h/k/e/Y";
die "xcopy failed" if $ret;
$ret = 0;
...

##</code><code>##

open(DAT,">>$resultOutput") || die("Cannot Open File");
print DAT "Bad username or password on the following machines:\n";

##</code><code>##

open DAT, ">>$filename" || die "foo";

##</code><code>##

open DAT, (">>$filename" || die "foo");

##</code><code>##

open(my $dat, ">>", $resultOutput")    or die("Cannot Open File");
print $dat "Bad username or password on the following machines:\n";