This method is common in centos.
Method 1:
GRUB: On the boot loader menu, type [e] to enter the editing mode. You will face a list of pilot projects. Find the following output line: kernel/vmlinuz-2.6.18-164.el5 ro root =/dev/vol/root rhgb quite
Press the arrow keys until the line is highlighted and then press e. Now, you can add 1 at the end of the text to instruct GRUB to guide the Linux mode of a single user.
Then press Enter to make the editing result take effect.
You will be taken with the edit mode screen. From here, press the B key and GRUB will guide the single-user Linux mode. After loading, you will face a shell prompt similar to the following: sh-3.2 # now, you can change the root command, the command is: passwd
You will be asked to retype the password for verification. After the password is changed, you can enter init 6 at the prompt to reboot. Then, you can log on as the root user as usual.
In the Password dialog box, enter the new password and enter the system.
Method 2:
Similar to the method, after entering the single-user mode, enter the command vi/etc/passwd at the prompt and remove the user's password transmission location x, force save, and restart! Modify the settings, force save the settings, and enter init 6 to restart the system. In the user dialog box, enter root and press enter to enter the system without entering the password. After the system restarts, it will be OK to change the password.
