Single-user mode is equivalent to runlevel 1 on the system. If runlevel 1 is not configured properly, you will not be able to boot into single-user mode. Rescue mode requires a boot media, but single-user mode is specified as a kernel option using the installed boot loader and does not require additional boot media. However, it does require that the boot loader is working properly and that the filesystem be mounted. It does not provide the ability to start a network connection.
Possible reasons to use single-user mode include
. Forgot root password
. Repair runlevel other than runlevel 1
To boot into single-user mode, boot the system with the single kernel parameter.
Specifying a boot parameter differs from architecture to architecture.
Booting into Single-User Mode per Architecture
Architecture Single-User Mode Command
x86, x86_64 Press any key at the Booting Red Hat Enterprise Linux(<kernel-version>) message to view the GRUB menu. Press the E key to edit the currently selected boot line. Append the line with the word single, and press B to boot the system.
Once in single-user mode, your filesystem are mounted, so any installed applications should be available. Use the exit command to exit single-user mode and reboot the system.