Web hosting bandwidth - 436 CHAPTER 30 MANAGING USERS Note As
436 CHAPTER 30 MANAGING USERS Note As in real life, a group can have many members and can be based around various interests. In a business environment, this might mean that a group is created for members of the accounting department, for example, or for the human resources department. By changing the permissions on files created by the group members, each group can have files that only the group members can access (although, as always, anyone with superuser powers can access all files). On a default Ubuntu system with just a handful of users, the group concept might seem somewhat redundant. However, the concept of groups is fundamental to the way Ubuntu works and cannot be avoided. Even if you don t make use of groups, Ubuntu still requires your user account to be part of one. In addition to actual human users, the Ubuntu system has its own set of user and group accounts. Various programs that access hardware resources or particular sets of files normally use these. Setting up system users and groups in this way makes the system more secure and easier to administer. Root User On most Linux systems, the root user has power over the entire system. Root can examine any file and configure any piece of hardware. Root typically belongs to its own unique group, also called root. Ubuntu is different in that the root account is deactivated by default. Instead, certain users, including the one set up during installation, can borrow root-like powers by simply typing their login password. This is done by preceding commands with sudo at the command- line prompt, or as needed when using GUI programs that affect system settings. If you wish, you can activate the root user account on your system and then log in to it when necessary. To activate the root account, use the following command: sudo passwd root After typing your own login password, you ll be invited to define a password for the root user. Because of its power, the root user can cause a lot of accidental damage, so it s rare for anyone to log in as root on bootup. Instead, you can switch to root user temporarily from an ordinary user account by typing the following: su This will prompt you for the root password and then log you in as root for as long as you need. When you ve finished, type exit, and you ll be returned to your ordinary user account.