Enter a level, single-user mode, change the root password (run level do not know watch here )
Specific operation is as follows:
Press the enter key while the power
2. enter the GRUB interface
3. Enter e, before the edit command guidance system
4. Select the second line of the line that begins with kernel, i.e., edit the kernel
5. enter e, the following interface
6. Enter a space, and then enter a number 1, i.e., after the start of operation of the guide system 1 level, single-user mode where the root password can modify the pattern
7. Enter Enter key to enter, save and return to previous level
8. At this time, according to B, boots, wait a little
9. After starting the user directly to the root, at this time can be modified Run passwd root password
10. After the amendment is successful, the reboot restart after it properly logged.
Extraneous: Changing the root password using this mode, you must be able to control the actual linux system filled with actual machine , that is, computer (server) in the side, and have the right to log in using single-user mode, or use remote tools, can not boot before doing the run level changes, but you can not use a single-user level.