[root@larrywen opt]# type adduser adduser is /usr/sbin/adduser [root@larrywen opt]# type useradd useradd is /usr/sbin/useradd [root@larrywen opt]# which useradd /usr/sbin/useradd [root@larrywen opt]# which adduser /usr/sbin/adduser [root@larrywen opt]# ls -l /usr/sbin/adduser /usr/sbin/useradd lrwxrwxrwx. 1 root root   7 Jul 21 14:11 /usr/sbin/adduser -> useradd -rwxr-x---. 1 root root 97040 Feb 24 2011 /usr/sbin/useradd

[root@larrywen /]# useradd zhink [root@larrywen /]# id zhink uid=501(zhink) gid=502(zhink) groups=502(zhink)