Q. User tom is a member of a group called sales and printer. I'd like to remove tom from a group called printer without editing any user configuration text files stored at /etc/ directory?
A. /etc/groups file defines group membership for each user. usermod command has -G option to set a list of supplementary groups which the user is also a member of. Each group is separated from the next by a comma, with no intervening whitespace. If the user is currently a member of a group which is not listed, the user will be removed from the group.
Step # 1: Find out user group identity
Use id command:
# id -nG {user-name}
# id -nG tom
Output:
sales printer
Step # 2: Remove user from printer group
Use the following syntax:
# usermod -G {groupname1,groupname2,...} {username}
To keep membership for sales only group (remove user tom from printer group), enter:
# usermod -G sales tom
# id -nG tom
Output:
sales
The following example remove user vivek from all groups except admin, audio, video and powerdev group:
# id -nG vivek
Output:
vivek adm dialout cdrom floppy audio dip video plugdev scanner netdev lpadmin powerdev admin
Modify group membership, enter:
# usermod -G admin, audio, video, powerdev vivek
# id -nG tom
Sample output:
vivek audio video powerdev admin
For more information, read usermod(8) command man page:
$ man usermod
- Email FAQ to a friend
- Printable version
- Rss Feed
- Last Updated: 3-3-08
{ 5 comments… read them below or add one }
Thanks for your website.
it’s very helpful.
lets say i want to add an existing user to an existing group. when the user belongs to other groups already. what command will i use.
using usermod-g “groupname” user will change the initial gropu of the user and delete him from another group.
usermod -G this will lead from the user being deleted ffrom all other groups except the one sspecified.
A user (pop)who is belong to SALES group. i want that pop is remove from SALES group. how can i do it. not tell me manually. i want command to remove it..
In one line (and nice for scripts):
Add a group: usermod -aG GROUP USER
Remove a group: usermod -G $(id -nG USER| sed -e ’s/GROUP //’ -e ’s/ /,/g’) USER
Can anyone tell me command(s) to add an user to a new group without mentioning all the groups the user previously belongs to? (I haven’t gone thru man)