I hope you have a better understanding of the groupmod command for group management in Linux. You can also use the id command to display GID, UID and other details. In case you are wondering, you can see the GID in the /etc/group file. rw-r-r- 1 abhishek testing 57 Feb 24 15:57 a.txt See it in the example below where I changed the group ID of group testing to 1020 and the file owned by this group still reflects the old GID. Second and more important thing is that the files owned by the group will be left with group ownership by a nonexistent group. First, there will be no checks performed regarding the login defs like GID_MIN, GID_MAX, SYS_GID_MIN, SYS_GID_MAX values to distinguish system groups and normal groups. Now this is a risky modification and should be avoided. You can change the GID of a group in the following manner: sudo groupmod -g GID groupname rw-r-r- 1 abhishek testgroup 0 Feb 24 16:39 ab.txtĪctually, the group ID remains the same even though the group name has been changed. It ‘changes’ the group ownership of the file to reflect the new group name: :~$ ls -l ab.txt Now, if I modify the group name from test_group to testgroup (removing the underscore from the name) :~$ sudo groupmod -n testgroup test_group rw-r-r- 1 abhishek test_group 0 Feb 24 16:39 ab.txt So, here’s a file belonging to user abhishek and group test_group. 1 Answer Sorted by: 8 AD mapping in SSSD is determined using an algorithm (probably a hash function) in the daemon itself: because it's built-in, if you keep the defaults the same, every computer using SSSD should map the IDs to the same value regardless of the computer being used. The good thing here is that even though you have changed the group name, it doesn’t affect any files owned by the group. If you want to change a group’s name, you can do that in this fashion: sudo groupmod -n new_groupname old_groupname I’ll use sudo in groupmod command examples here. Modifying group is an administrative task this is why you need to be a sudo user or use the root account to run this command. The syntax of the command is this: groupmod GROUP

The groupmod command in Linux modifies the given group by changing its name or the group ID (GID). In this tutorial, you’ll learn about the groupmod command. Geek University recommends the following video course to get you started with Linux.In earlier articles, you learned groupadd and groupdel commands. New groups are usually assigned GIDs starting from 1000: The GID of 0 corresponds to the root group and the GID of 100 usually represents the users group. Just like with UIDs, the first 100 GIDs are usually reserved for system use. Groups in Linux are defined by GIDs ( group IDs). If we create a new user on our Ubuntu system, it will be given the UID of 1001: When you create a new account, it will usually be give the next-highest unused number. For example, new users in Ubuntu start from 1000: New users are assigned UIDs starting from 500 or 1000. The range of values for a GID varies amongst different. Most Linux distributions reserve the first 100 UIDs for system use. A group identifier, often abbreviated to GID, is a numeric value used to represent a specific group. Notice how the root user has the UID of 0. This number is used to identify the user to the system and to determine which system resources the user can access.

A UID (user identifier) is a number assigned by Linux to each user on the system.

Gid linux