getpwnam returns undef if the account doesn't exist. Try this:

my $username = SomeSubToGetUsername;
my $check = getpwnam($username);
if ($check) {
# account exists
...
}
else {
# account does not exist
...
}
[download]

Hope this helps.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1