[root@linux samba]# /usr/sbin/useradd -g machines -d /var/lib/nobody -s /bin/redwar$
Usage: useradd [options] LOGIN

Options:
  -b, --base-dir BASE_DIR       base directory for the new user account
                                home directory
  -c, --comment COMMENT         set the GECOS field for the new user account
  -d, --home-dir HOME_DIR       home directory for the new user account
  -D, --defaults                print or save modified default useradd
                                configuration
  -e, --expiredate EXPIRE_DATE  set account expiration date to EXPIRE_DATE
  -f, --inactive INACTIVE       set password inactive after expiration
                                to INACTIVE
  -g, --gid GROUP               force use GROUP for the new user account
  -G, --groups GROUPS           list of supplementary groups for the new
                                user account
  -h, --help                    display this help message and exit
  -k, --skel SKEL_DIR           specify an alternative skel directory
  -K, --key KEY=VALUE           overrides /etc/login.defs defaults
  -m, --create-home             create home directory for the new user
                                account
  -l,                       do not add user to lastlog database file
  -M,                       do not create user's home directory(overrides /etc/login.defs)
  -r,                       create system account
  -o, --non-unique              allow create user with duplicate
                                (non-unique) UID
  -p, --password PASSWORD       use encrypted password for the new user
                                account
  -s, --shell SHELL             the login shell for the new user account
  -u, --uid UID                 force use the UID for the new user account
[root@linux samba]#