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Network Operating Systems-I

notes Because it is so dangerous to be logged in as root, you should never use this account unless you
have to. The root account is meant to be used by the System Administrator to perform certain
duties which can be destructive and therefore should only be performed by an expert. Some
examples are emptying log files, mounting and unmounting file systems (more on this later
under Getting to CD’s and Floppies), installing or removing programs, and creating or deleting
user accounts.

If you are using Mandrake Linux, you will have a tool available to perform the most common
administration tasks, even when logged in as a regular user. This is called the Mandrake Control
Center, which you may find on your desktop or in the Configuration menu. It will ask you for
the root password when you start it for security reasons. As a result of this handy tool, you may
never need to actually log in as root.

Becoming superuser

No phone booth needed. The obvious way is to login as root. That’s the best way to do it if you
plan on doing a bunch of system maintenance type stuff, but it can be a pain if you’re logged in
as User with an X session and 14 programs open and connected to the Internet and you just need
to copy one file into /usr/lib so you can run this program you just downloaded. Fear not, there
is a better way. Type this:

[user]$ su
Password:*****
[root]#
Bang! Just like that, you are SuperUser! A few cautions: Although you are now SuperUser, this
is not a “login” shell, so your environment hasn’t changed. The biggest way this will effect you
is that some programs you normally run as root may appear to be missing. That’s because your
PATH environment variable, the list of places Linux looks for executables, does not contain /sbin
or /usr/sbin. If you try to run a command like shutdown (see below) and it complains, try typing
/sbin/shutdown instead. That should do it.
When you are finished with your maintenance tasks you should immediately change back to
normal user mode:
[root]# exit
[user]$

Note While you are SuperUser, your command prompt looks different. An ordinary
user is prompted with the dollar sign ($) while SuperUser gets a pound sign (#).
This makes it easy to tell which mode you are in. (This is true on most distributions, but the
prompts may be different on different distributions, and they can be customized.)
11.2 normal users in Linux

A “root” user has the power to do anything on a Linux system. A “normal user” will be assigned
some of these capabilities based on what group they are in, but is generally prevented from
running any commands that may affect the system outside of their home directory. Users can be
granted “sudo” rights, which allows them to run the sudo command and temporarily be granted
root privileges.

210 LoveLy professionaL university