我先 make user directory，再用 useradd -u 600 -g staff -m -p 123456 -d /home/staff/peter peter，但最後 /etc/group 既 staff 竟然無 peter 呢個user，你地有無人試過？係唔係我做錯 d 乜野？

The primary group for "peter" is "staff" when you create the account. You will not see "peter" listed in /etc/group unless you have assigned a secondary or more group to it.

Take a look at /etc/passwd, you will find the gid of "peter" which should match the gid (staff) in /etc/group.

OIC

THANK A LOT