RHEL Linux - Red Hat System Administration Practice Exam

Which UID is always assigned to the superuser account, root?

1. 500

2. 1000

3. 1

4. 0

The correct answer is: 0

The superuser account, commonly known as the root account, is a critical component of Unix-like operating systems, including Red Hat Enterprise Linux (RHEL). The UID (User Identifier) that is always assigned to the root user is 0. This special UID grants unrestricted access to all commands and files on the system, allowing the root user to perform administrative tasks such as installing software, modifying system configurations, and accessing all users’ files. The choice of UID 0 for the root user is a standard in Unix-like systems, establishing a clear distinction for the highest level of permissions and control. Other user accounts, whether they are system accounts or regular user accounts, always receive UIDs that are greater than 0. The rationale behind this approach is to ensure that the root account has the highest level of authority, which is essential for system integrity and security. In contrast, UIDs like 500 and 1000 are typically assigned to the first regular user accounts created on many Linux distributions. This practice varies slightly across different distributions, but those UIDs are not relevant to the root account. As such, the only correct answer specifying the UID for the root account is 0.