Which runlevel is specifically designed for single-user mode in Linux?

The runlevel specifically designed for single-user mode in Linux is runlevel 1. In this mode, the system operates in a minimal state, providing only the essential services needed to perform administrative tasks. This typically includes a single user environment where the user can make changes to the system, troubleshoot issues, or perform maintenance without interference from other users or services.

Running in single-user mode is essential for tasks like password recovery, disk repairs, or modifying critical system files since it eliminates the complications that can arise from having multiple users logged in or services running. This mode is particularly useful for system administrators when needing to resolve issues that prevent the system from booting normally.

Other runlevels serve different purposes; for instance, runlevel 0 is used to halt the system, runlevel 2 is typically a multi-user mode without network services, and runlevel 3 provides multi-user support with network services enabled. Thus, runlevel 1 distinctly stands out as the designated single-user mode, emphasizing its role in providing a safe environment for system maintenance.