##
system(
$useradd,
qq|-c "fullname"|,
...
##
##
-c "value-of-$fullname"
##
##
system ($useradd,
'-c', $fullname,
'-d', "/home/sites/site$site_count/users/$username",
'-g', "site$site_count",
'-G', "site-adm$site_count",
'-p', $password,
'-s', '/bin/false',
'-u', $uid, $username);
##
##
system('cat -n /etc/group');
system('cat', '-n /etc/group');
system('cat', '-n', '/etc/group');