Shell read read console input, use of read

1.read Read console input

read yes Shell Built in commands , It is used to read data from standard input and assign values to variables . If there is no redirection , The default is to read the data entered by the user from the keyboard ; If redirected , Then you can read data from the file .

1.1 Basic grammar

read (options) (variables)

options Said options , As shown in the following table ;
variables Represents the variable used to store data , There can be one , There can be more than one .
options and variables It's all optional , If the variable name is not provided , Then the read data will be stored in the environment variable REPLY in .
①options：

• -p： Specify the prompt when reading the value ;
• -t： Specifies the time to wait while reading the value （ second ） If -t Not adding means waiting

②variables

• Variable ： Specifies the variable name of the read value

1.2read Use

If the set time is exceeded , Then skip directly