It is important to log in with your user account instead of as the root user when performing day-to- day tasks. Some of the graphical administration tools will prompt you for the root password if you try to run them as a regular user. But, what if you are logged in as a user and need to perform an operation only the root user can do? It would be time consuming to close all your open windows, log out of the graphical desktop, log back in as root, execute root-only commands, log out again, and then log back in with your user account.
Instead, you can temporarily start a terminal session as root. From a shell prompt, execute the following command to temporarily become the root user:
Notice the space and then a hyphen after the su command. These are extremely important parts of the command. Without it, you have root privileges but you don’t inherit any of the environment variables of the root user, including the important PATH variable previously discussed. Without the proper PATH that includes /sbin/ and /usr/sbin/, it will appear as if many administrative commands don’t exist. After executing the su - command, you will be prompted to enter the root password before being granted access. If the correct root password is entered, you will notice that the prompt changes to show that the root user is the currently logged-in user.
When you no longer need to be root, type the exit command and then press Enter to return to your user shell.