6 Basic Concepts
If this is your rst encounter with a Linux system you probably want to learn something
about the basic concepts of Linux before getting started. The graphical user interfaces
of Linux, Mac OS* and Windows* show rather similar desktop components, which
makes it easy to move from one graphical environment to the next. However, if you
take a look at the underlying system you will soon notice some dierences.
The following sections are meant to guide you through the rst steps with your Linux
system and to help Linux “newbies” to familiarize themselves in their new operating
system. You will learn about the user concept of Linux, the structure of the Linux le
system (where to nd what in the directory tree) and how to deal with access permis-
sions for les and directories, which are an essential feature in Linux.
Users who have been working with Mac OS will probably recognize that the concepts
explained in the following sections are rather similar to what they know already from
Mac OS. Windows users may realize some crucial dierences which are worth noticing.
6.1 User Concept
From the beginning, Linux has been designed as a multiuser system: Any number
of users can simultaneously work on one machine. These users can connect to the
system via dierent terminals or network connections. Usually users need to log in
to the system before starting a session. Personal information and individual desktop
conguration are stored separately for each user.
6.1.1 Distinct User Roles
Among the users working on a machine, Linux distinguishes between dierent kinds
of user roles: you can log in to a Linux machine as a “normal” user or as a superuser
(administrator), traditionally called root in Linux. The superuser has privileges which
authorize him to access all parts of the system and to execute administrative tasks.
He or she has the unrestricted capacity to make changes to the system and has un-
limited access to all les. If you are logged in as a normal user you lack these privi-
leges. User and root can of course be the same physical person but acting in dierent
roles.
The root user account is always created on your Linux system by default — during
installation you are therefore requested to specify a password for root. Which other
users can log in to your system depends on the method of authentication you choose
during installation (see Section 1.11, “Create New User” (page 17)).
Basic Concepts 73
