What is the run level for single user mode?

Single user mode in Linux is represented by run level 1. This mode is primarily used for administrative tasks where only the root user is allowed access, and minimal services are started. It operates without a network and is useful for troubleshooting as it provides a safe environment to perform maintenance tasks such as repairing filesystems or resetting passwords.

Run level 1 is intentionally stripped down to ensure minimal interference, allowing system administrators to focus on important recovery and maintenance actions without the complications of a full multi-user environment. In this mode, the system does not start network services or other non-essential processes, making it easier to troubleshoot any issues.

The other run levels serve different purposes. Run level 0 is used to halt the system, while run levels 2 and 3 enable multi-user modes with varying degrees of functionality and service availability. Understanding these run levels is crucial for Linux administration, especially during system recovery tasks.