Read of shell internal value command

Shell Internal value command read

read Read console input

 The goal is :
	 understand read Role of command 
	 Use read Assign values to multiple variables 
	 Use read Read a character 
	 Use read Limit time input 
	
 Introduce :
	read yes shell Built in commands , Used to read data from standard input and assign it to variable , If there is no redirection , The default is to read the data entered by the user from the terminal console , If redirected , Then you can read data from the file .
	
 grammar :read [options] [var1 var2]
options Said options , As shown below ,var Represents the variable used to store data , It could be a , It can be multiple 
	-n num  Read num Characters , Instead of a whole line of characters 
	-p prompt  Display prompt message , The tip is prompt
	-s  silent mode , The input characters will no longer be displayed on the screen 
	-t seconds  Set timeout , The unit is in seconds , If the user does not complete the input within the specified time , that read Will return a non 0 The exit status of , Indicates a read failure .

Instance of a : Multiple variable assignments

Example 2 : Read a character

Examples of three : Limit time input

Summary

read What is the order 
	 Used to read standard input ( Terminal console user input data )
read Assign values to multiple variables 
	read var1 var2
read Read a character 
	read -n 1 var1
read Limit time input 
	read -t  Number of seconds  var1