How to boot system to single user mode (x86)

If you have an x86 host and you want to boot into single user mode, you can see following tips.

1. When GRUB menu appear, type e. It will bring you to the next detailed menu.
2. The next window will appear like below. Choose kernel and type e again.
   root (hd0,1,a)
   kernel /platform/i86pc/multiboot
   module /platform/i86pc/boot_archive

3. Enter a space and -s at the end of kernel line. Then press enter to return on the main menu.
   grub edit> kernel /platform/i86pc/multiboot -s
4. Type b to boot system into single user mode.