8.4 Becoming Root
As you learned inSection 7.1, User Concept, some tasks in Linux
require root permissions, otherwise they cannot be executed. In order
to temporarily become root in a shell, proceed as follows:
-
Enter su. You are prompted for the root
password.
-
Enter the password. If you mistyped the root password, the
shell displays a message. In this case, you have to re-enter
su before retyping the password. If your password is
correct, a hash symbol # appears at the end of the
prompt, signaling that you are acting as root now.
-
Execute your task. For example, transfer ownership of a file to a
new user which only root is allowed to do:
chown wilber kde_quick.xml
-
After having completed your tasks as root, switch back to your
normal user account. To do so, enter
exit
The hash symbol disappears and you are acting as
normal
user again.
Alternatively, you can also use sudo (superuser
do
) to execute some tasks which normally are for roots
only. With sudo, administrators can grant certain users root
privileges for some commands. Depending on the system configuration, users
can then run root commands by entering their normal password only.
Due to a timestamp function, users are only granted a ticket
for a restricted period of time after having entered their password. The
ticket usually expires after a few minutes. In openSUSE, sudo requires
the root password by default (if not configured otherwise by your
system administrator).
For users, sudo is comfortable as it prevents you from switching
accounts twice (to root and back again). To change the ownership of a
file using sudo, only one command is necessary instead of three:
sudo chown wilber kde_quick.xml
After you have entered the password which you are prompted for, the
command is executed. If you enter a second root command shortly after
that, you are not prompted for the password again, because your ticket is
still valid. After a certain amount of time, the ticket automatically
expires and the password is required again. This also prevents unauthorized
persons from gaining root privileges in case a user forgets to switch
back to his normal user account again and leaves a root shell
open.
