link = http://www.freebsd.org/ports/

pw is a command line utility to create, remove, modify, and display users and
groups, and functions as an editor of the system user and group files.
It is designed to be useful both as a directly executed command and for use
from shell scripts.

pw is a powerful and flexible means to modify accounts, but adduser is
recommended for creating new accounts, and rmuser for deleting accounts.

chpass allows both the system administrator and normal users to adjust
passwords, shells, and personal information. passwd is the more common
means to change passwords specifically, however.

rmuser
rmuser removes users from the system, including any traces beyond the user
database. rmuser performs the following steps:

    1.Removes the user's crontab(1) entry (if any).
    2.Removes any at(1) jobs belonging to the user.
    3.Kills all processes owned by the user
    4.Removes the user from the system's local password file.
    5.Removes the user's home directory (if it is owned by the user)
    6.Removes the incoming mail files belonging to the user from /var/mail.
    7.Removes all files owned by the user from temporary file storage areas
      such as /tmp.
    8.Finally, removes the username from all groups to which it belongs in
      /etc/group.

    Note: If a group becomes empty and the group name is the same as the
    username, the group is removed; this complements the per-user unique
    groups created by adduser(8).