Every user on Linux belongs to a primary group. A user’s primary group is usually the group that is recorded in your Linux system’s /etc/passwd file. When a Linux user logs into their system, the primary group is usually the default group associated with the logged in account.

What is effective group Linux?

This group is the user’s primary group ID, stored in the user database (typically /etc/passwd ). This group becomes the real and effective group ID of the shell or other program launched by the login process. Nowadays, a process can be in multiple groups, so users can be in multiple groups, too.

How do Unix groups work?

A group is a collection of users who can share files and other system resources. For example, users who working on the same project could be formed into a group. Each group must have a name, a group identification (GID) number, and a list of user names that belong to the group. …