17.3. Booting into Single-User Mode
One of the advantages of single-user mode is that you do not need a boot CD-ROM; however, it does not give you the option to mount the file systems as read-only or not mount them at all.
If your system boots, but does not allow you to log in when it has completed booting, try single-user mode.
In single-user mode, your computer boots to runlevel 1. Your local file systems are mounted, but your network is not activated. You have a usable system maintenance shell. Unlike rescue mode, single-user mode automatically tries to mount your file system.
Do not use single-user mode if your file system cannot be mounted successfully.
You cannot use single-user mode if the runlevel 1 configuration on your system is corrupted.
On an x86 system using GRUB, use the following steps to boot into single-user mode: