Pipe symbol
Take the previous result as input to the following command
Job Control
Ctrl +z pause the current task into the background
Restart incoming
Jobs view the commands in the background
BG is in the background and running
Sleep 1000 Pause
FG does not add parameters but only transfers the most recent command
Tune in to the background and run
Variable
viewing system Variables
Custom variables
The first variable naming rule cannot be a number
Special characters need to use single quotation marks
The summation of variables
Current Terminal
Pstree
Global environment variable Export custom variable
Child shells can also query variables
Cancel variable unset
environment variable configuration file
Load configuration file
The system level is under/etc/.
User-level./.BASHRC
PS1/ETC/BASHRC inside definition
Modify PS1
Do not add square brackets
Add color display
PS2
Shell Basics 2
