When you enter into the world of dedicated servers, you are going to hear new terminology, acronyms, and strange ways of pronouncing software titles. One common term that experienced system administrators will throw around is “root”. Just as the roots of a tree are its strength and foundation, root on a Linux server is the powerhouse. It is the only user on the server with absolute power. Other names for root include “superuser” and “admin”.
Having a root user on a server is important because the alternative is to allow a normal user to have administrative permissions, have access to system files, and have the ability to execute powerful commands, even ones that could cripple the server. Therefore, the policy of restricting administrative commands from normal users is a standard for all Unix-like operating systems, including Linux, Solaris, BSD variants, and Mac OS X. More recent versions of Windows also follow a similar policy.
When you do need to become root, there two different methods, depending on your Linux distribution. Many Linux distributions commonly used on dedicated servers, such as Redhat Enterprise Linux, Fedora, CentOS, SUSE Linux Enterprise, Debian and others rely on “su“, which stands for superuser. After you have connected to your server via SSH, you can become root with the following command:
Other distributions, such as Ubuntu Server Edition, rely on a command called “sudo“. Rather than logging in as the root user, you must insert “sudo” before any commands you wish to run as root. The system will prompt you for a password but will not log you in as root, unless you run “sudo su”. For example, to execute the copy command with sudo, type:
sudo cp filename-a new-location
Then, enter your password.