Essential for high salary-Linux Centos7 failure recovery, optimized startup and cracking of user passwords

1. Linux Centos7 boot process 1. Overview of the boot process

two。 Understand what an init process is

3.Systemd unit type

4. Systemd target corresponding to run level

II. MBR fault recovery

1. Let's do the experiment.

There are three steps to mbr recovery:

1. Back up the MBR boot sector to another disk

two。 Simulated destruction of the MBR boot sector

3. Boot mirror first aid mode for MBR sector recovery

two。 Restart the computer to view the device files

3. Create primary partition, format and mount

4. Backup file

5. Overwrite corrupted file

6. Enter the system first aid mode, restart the computer and quickly press the ESC key in the loading interface.

7. Create a mount point recovery file

8. Try to turn on the computer.

III. Grub menu recovery

Three steps to restore the 1.grub menu

two。 Boot first aid mode and load system image

3. Re-establish the loaded sda partition

4. Rebuild the grub menu profile

5. Exit the bash environment

6. Restart

Where do I put the 1.grub menu configuration file

two。 Delete the configuration file

3. Access to the system first aid

4. Re-establish the loaded sda partition

5. Rebuild the grub menu

6. Restart the computer and try to log in.

four。 Crack and modify Linux user password

1. Enter first aid mode

two。 Direct modification

3. Verify that you can log in.

five。 System service self-startup and self-shutdown, character interface and graphical interface

1. Switch between character interface and graphical interface

two。 Boot character interface boot

3. De-counterfeiting terminal setting system service on and off

4. Use commands to shut down and self-start services