Ubuntu is a Debian-based Linux operating system. By default, there is no superuser (Root), but some system operations must be performed only with the permissions of a Super User, for example, manually release the memory. In other Linux operating systems (such as fedora), you can use Su to switch to a Super User. After the su command is entered, the system requires the root password. However, in Ubuntu, we do not know what the root password is. In this way, you need to use other methods to switch to a Super User In ubuntu. There are two main methods: 1) Sudo-I sudo is an enhanced version of Su, meaning do something as the supervisor. You can get the root permission without a password. However, it also has many restrictions. For example, by default, the root permission can only be used within five minutes. 2) If you want to keep using the root permission, you still need to use Su or get the root password. Use sudo passwd root to set the root password. Then you can use the su command freely.