Disable the aec key when centos is started.

Press any key to enter the GRUB boot program interface, where you can enter c for parameter input. if the parameter is 1, you can enter single-user mode, you can directly change the root password of the system. There are certain security risks in some production environments. You can set the password here by 1. first, set an md5 encrypted ciphertext:

Press any key to enter the GRUB boot program interface, where you can enter c for parameter input. if the parameter is 1, you can enter single-user mode, you can directly change the root password of the system. There are certain security risks in some production environments.

You can set a password here:

1. first set an md5 encrypted ciphertext:

# Grub-md5-crypt // will generate an encrypted string

2. modify the/etc/grub. conf file.

# Vim/etc/grub. conf

Add a line above the title and enter password -- md5 xxxxxxxxx (the ciphertext character generated in the first step)

3. save and restart. When you enter the grub boot page again, enter p and password. Improve security.