A command that lets you understand the common arguments of the shell command

We know that there are two ways to receive incoming parameters in Shell. One is to pass parameters through a script, and the other is to receive incoming parameters through read. A simple example of passing a parameter through a script is as follows:

#  It's passed through the script, here $0 Refers to the script name ,$1 For the first 1 A parameter ,$2 For the first 2 A parameter 
[root@host ~]# ./script.sh 1 2
Total = 3
[root@host ~]# vim script.sh
#!/bin/bash
function add() {
  total=$(expr $1 + $2)
  echo -e "Total = $total"
}
add $1 $2

To receive incoming parameters through read, consider the basic format of read:

[

read [-rs] [-a ARRAY] [-d delim] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [var1 var2 var3......]

]

[root@host ~]# ./script.sh 
Enter Password:
The password your input is: Test@1234\
[root@host ~]# vim script.sh
#!/bin/bash
read -n10 -t30 -r -s -d $ -p "Enter Password:" password
echo -e "\nThe password your input is:$password"

-ES15en prompt statement, followed by input prompt message, here 'Enter Password: ' -ES18en number of arguments, sometimes to limit password length, or other input length limits, such as [Y/N], where only one bit is entered,-n1 -s block echo, no display of input content on the screen, 1 generally used for password input -ES23en wait time, here set 30 seconds, no input or incomplete input within 30 seconds, terminate -ES24en input threshold, here $, input to $, natural termination of input -r blocks the translation of special characters \, which are then treated as normal characters

From the above 1 example, basically includes most of the common functions above, especially -ES27en, -ES28en, -ES29en, -ES30en and other parameters, you can learn the read command very well

conclusion