Elevating privileges

As an administrator of the RHEL server or desktop system, there will be times when root access will be required. The root user or user ID 0 is the local administrator on the system. Although it's possible to log in to the system as a root user, as with most systems, it's preferred that root access is gained as required. There are two mechanisms that can be used:

• The substitute user or the su command
• Using the sudo command

First, we will look at the su command.

The su command

When a user issues the su command without specifying a username, they will be prompted for the root password. If authentication is successful, they will be presented with a root shell. The following are the valid mechanisms to gain root privileges with su:

• su -l: This presents a full login shell for root; all environment variables are set for root. The working directory of a user is changed to become the home directory of the root user, which is usually /root.
• su: This is the same as su -l.
• su...