Linux Single User Mode

1. Ubuntu

a. 开机按 shift 进入GRUB



In fact: "generic" or "recovery mode" whichever is OK!

b. "e"



c. ctrl+x or F10



d. poweroff



but:  shell> reboot -f            /// You can make it!

2. CentOS6

a. GRUB



b. "e" ， 末尾输入：空格 1



c. "b"  boot

3.
CentOS7

Boot
your system in single user mode.

chroot your system

chroot /sysroot

reset the root password.

passwd

Update SELinux information.

touch /.autorelabel

Exit chroot

exit

Reboot your system.

reboot

Login with new password.

That’s All.