Linux Basics/User management (System administrator)

The system administrator (superuser) and its functions The most important user in Linux is: root UID: 0, GID: 0 Root can access everything in the system! The „su” command: Changing user and executing command: For example, we can become user mary: su mary If we use dash, then we get the whole environment of mary: su - mary We can add a group with the sg command. For example, we can add info: sg info Sudo command With sudo command we can execute superuser commands. It asks the user's password, this is important because we don't want anybody to modify our system. Ubuntu-based systems get root permissions only by sudo, root user doesn't get password. We don't edit sudo's settings from directly the file. We use the following command instead: # visudo Settings → in /etc/sudoers file Syntax: <username> ALL=NOPASSWD: ALL Example: joska ALL=NOPASSWD: ALL Without NOPASSWD it asks the given user's password. Setting superuser permission: ALL=(ALL:ALL) ALL