There is nothing any issue with adduser
script. I had tested itself on diff type of OS. Please check it again with abc or xyz (do not start with numeric). After that use numeric start if it success.
Do not copy or paste the given script from http://www.indianGNU.org
Just write it manually.
[root@indianGNU.org ~]# ./adduser
Changing password for user 3xy3y.
passwd: all authentication tokens updated successfully.
User 3xy3y's password changed!
User 3xy3y will be forced to change password on next login!