Linux添加用户（user）到用户组（group）

将⼀个⽤户添加到⽤户组中，千万不能直接⽤：

usermod -G groupA

这样做会使你离开其他⽤户组，仅仅做为 这个⽤户组 groupA 的成员。应该⽤ 加上 -a 选项：

usermod -a -G groupA user

(FC4: usermod -G groupA,groupB,groupC user)

-a 代表 append， 也就是 将⾃⼰添加到 ⽤户组groupA 中，⽽不必离开 其他⽤户组。命令的所有的选项，及其含义：Options:

-c, –comment COMMENT new value of the GECOS field

-d, –home HOME_DIR new home directory for the user account

-e, –expiredate EXPIRE_DATE set account expiration date to EXPIRE_DATE-f, –inactive INACTIVE set password inactive after expirationto INACTIVE

-g, –gid GROUP force use GROUP as new primary group-G, –groups GROUPS new list of supplementary GROUPS-a, –append append the user to the supplemental GROUPSmentioned by the -G option without removinghim/her from other groups

-h, –help display this help message and exit

-l, –login NEW_LOGIN new value of the login name-L, –lock lock the user account

-m, –move-home move contents of the home directory to the newlocation (use only with -d)

-o, –non-unique allow using duplicate (non-unique) UID

-p, –password PASSWORD use encrypted password for the new password-s, –shell SHELL new login shell for the user account-u, –uid UID new UID for the user account-U, –unlock unlock the user account查看⽤户所属的组使⽤命令：

$ groups user

或者查看⽂件：

$ cat /etc/group