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:
 * If we use dash, then we get the whole environment of mary:
 * We can add a group with the sg command. For example, we can add 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:
 * Settings → in /etc/sudoers file
 * Syntax:  Example:
 * Without NOPASSWD it asks the given user's password.
 * Setting superuser permission:
 * Syntax:  Example:
 * Without NOPASSWD it asks the given user's password.
 * Setting superuser permission: