Linux: File Ownership

Users and Groups

Linux makes use a users and groups. When looking at /etc/passwd you can see the user and group ids of all users on the system.

redhat:x:30582:30583::/home/redhat:/bin/bash
manali:x:30583:30584::/home/manali:/bin/bash
armtest:x:30584:30585::/home/armtest:/bin/bash

Each user is assigned a user Id and group id. The default group in Redhat is a group with the same name as the user.

The groups are defined in /etc/group. A user may be a member of more than one group.

redhat:x:30583:
manali:x:30584:
armtest:x:30585:

File Ownership

Files have a User and Group Owners. The test file is owned by user michael and group test. In this case the file cna be read and edited by michael and all members of the root group.

-rw-rw-r-- 1 michael root 0 Aug 15 20:41 test

Directories can also be assigned to a group. This allows the files stored in it, to be shared by a group.

Change the User Owner

chown <newuser> <file>

Change the Group Owner

chgrp <new_group> <file>