Interactive Shell scripts – reading user input

The read command is a shell built-in command for reading data from a file or keyboard.

The read command receives the input from the keyboard or a file until it receives a newline character. Then, it converts the newline character into a null character:

1. Read a value and store it in the variable, shown as follows:

   read variable
   echo $variable
   

   This will receive text from the keyboard. The received text will be stored in the variable.

2. Command read with prompt. Whenever we need to display the prompt with certain text, we use the –p option. The option -p displays the text that is placed after –p on the screen:

   #!/bin/bash
   # following line will print "Enter value: " and then read data
   # The received text will be stored in variable value
   read -p "Enter value :  " value

   Output:

   Enter value : abcd
   

3. If the variable name is not supplied next to the read command, then the received data or text will be stored in a special built-in variable called REPLY. Let's write...