Can you delete a user from a group in Linux?

Can. Deletion method: 1. Use usermod to delete the user from the group, the syntax is "sudo usermod -G root username"; 2. Use gpasswd to delete the user from the specified group, the syntax is "sudo gpasswd -d username group name"; 3. Edit "/etc/group" file to manually remove users from groups.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

In Linux, a user can be a member of one primary group and one or several secondary (secondary) groups. The file "/etc/group" defines group membership for each user in a Linux system.

In this tutorial, we will learn how to delete a user in a Linux group. We will use both methods and will also show how to manually remove a user from a group by deleting it from the "/etc/group" file.

Create Linux User

For the purpose of this tutorial, we will create a user named "testuser". When a new user is created, a new primary group with the same name as the user is also created.

We will create a new user by issuing the following command:

$ sudo useradd -m testuser

Now we can create a password for this user:

$ sudo passwd testuser
Changing password for user testuser.
New password: 
BAD PASSWORD: The password contains the user name in some form
Retype new password: 
passwd: all authentication tokens updated successfully.

I used the same password as my username, so I got a warning that some form of the username should not be included in the password.

Add users to groups

First, we will create two new groups using the groupadd command, the command will be as follows:

$ sudo groupadd testgroup1$ sudo groupadd testgroup2

Now we add the "testuser" user to the two groups created above and add the "testuser" user to the "root" group using the following command:

$ sudo usermod -a -G root testuser
$ sudo usermod -a -G testgroup1 testuser
$ sudo usermod -a -G testgroup2 testuser

Okay, now take a look at the "/etc/group" file and you can see that "testuser" is a member of these three groups.

$ cat /etc/grouproot:x:0:testuser.............testuser:x:1001:testgroup1:x:1002:testusertestgroup2:x:1003:testuser

Find out which group the user belongs to

We can also use the following two alternative methods to check which group the user belongs to

$ groups testuser
testuser : testuser testgroup1 testgroup2 root$ id -nG testuser
testuser testgroup1 testgroup2 root

You can see that the output is very similar and these commands accomplish the same thing.

Use usermod to remove users from groups

We can use the usermod command to remove one user from one or more groups at a time. When using usermod, you must specify which secondary groups the user will be kept in. Let me explain with an example.

$ groups testuser
testuser : testuser testgroup1 testgroup2 root

In order to remove the user "testuser" from the "testgroup1" and "testgroup2" groups, run the following command (i.e., keep only testuser in the "root" group, which is Main "testuser" group):

$ sudo usermod -G root testuser

Results$ groups testuser
testuser : testuser root

So to divide users into more groups you need to mention separated by comma (,) The group name, for example:

$ sudo usermod -G root,testgroup1 testuser

Results# groups testusertestuser : testuser root testgroup1

Use gpasswd to remove the user from the group

Another way to accomplish similar results One command is gpasswd. Unlike usermod, we use this command to remove users from specified groups.

To remove a user from a specific group, we can use the gpasswd command:

$ sudo gpasswd -d testuser root
Removing user testuser from group root

$ groups testuser
testuser : testuser testgroup1 testgroup2

$ sudo gpasswd -d testuser testgroup1
Removing user testuser from group testgroup1

$ groups testuser
testuser : testuser testgroup2

Removing a user from a group (manually)

We can also remove users from groups by manually editing the file '/etc/group'. The effects of this method will be applied to the user after a reboot.

You can edit the "/etc/group" file using your favorite text editor:

$ cat /etc/group
.............sssd:x:993:sshd:x:74:chrony:x:992:vagrant:x:1000:slocate:x:21:vboxsf:x:991:testuser:x:1001:testgroup1:x:1002:testusertestgroup2:x:1003:testuser$ groups testuser
testuser : testuser testgroup1 testgroup2 root

Now we will manually edit the last two entries to remove testuser and remove testuser from testgroup1 and testgroup2 (the edited file should look like this):

$ cat /etc/group.............
sssd:x:993:
sshd:x:74:
chrony:x:992:
vagrant:x:1000:
slocate:x:21:
vboxsf:x:991:
testuser:x:1001:
testgroup1:x:1002:
testgroup2:x:1003:

The changes will be made after a reboot and the user is now removed from both groups:

$ groups testuser
testuser : testuser root

Conclusion

In this tutorial, we learned how to remove a user from a group using usermod, gpasswd, and manually deleting the user from the “/etc/group” file.

Related recommendations: "Linux Video Tutorial"

The above is the detailed content of Can you delete a user from a group in Linux?. For more information, please follow other related articles on the PHP Chinese website!