Linux study notes (12) -- login, logout and shutdown

This article takes CentOS7this as an example.

Directory structure of this article

1 Login and logout

1.1 Login

• Linux is a multi-user and multi-tasking operating system, and then use *system administrator** to configure the account to enter the system.
• When logging in, try to log in with the root account as little as possible to avoid misoperations with excessive permissions.
• If you need rootpermissions, you can log in as a normal user and then use su- 用户名the command to switch to the system administrator identity.

1.2 Log out user

logout

• Note: This command is not valid at the graphics run level and is valid at run level 3 .
  
  

2 Shut down and restart

2.1 Shut down immediately

shutdown -h  now

Shut down after 2.2 N minutes

shutdown -h [N]  

2.3 Restart the computer immediately

 shutdown -r now 

• Among them:
  hRepresentative halt
rRepresentativereboot

2.4 Shutdown

halt    

2.5 Restart the computer immediately

reboot

2.6 Synchronize memory data to hard disk

sync

2.7 Special attention

• When restarting or shutting down the system, the command is first executed syncto write the memory data to the disk to prevent the loss of important data.