gpasswd (Add and Delete Users to Group)
The gpasswd (Group PASSWorD) command is often used to manage group members. With the -a option, you can add a user to a group. With the -d option, you can delete a user from a group. With the -M option, you can register all group members in a group.
Using this command with no option, you can also create a password for a group. As password creation isn’t a frequently used functionality of the command, you may find it easy to memorize with the fact that the gpasswd command was originally designed to manage the /etc/group file including group passwords.
Add a user to a group (-a option)
To add a user to a group, run the gpasswd -a [user name] [group name] command as the superuser. For example, to add user_a to a sudo group, run the command below. (You can get the same result as that of the usermod -aG command. You just need to be careful because the order of arguments is different).
gpasswd -a user_a sudo
To check the group status, run the groups command. You can see that user_a is now a member of the sudo group.
groups user_a
user_a : group_a sudo group_b group_c
Delete a user from a group (-d option)
To delete a user from a group, run the gpasswd -d [user name] [group name] command as the superuser. For example, to delete user_a from the sudo group, run the command below.
gpasswd -d user_a sudo
Removing user user_a from group sudo
To check the group status, run the groups command. You can see that user_a is no longer a member of the sudo group.
groups user_a
user_a : group_a group_b group_c
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