Reading n characters without pressing the return key

The bash command read inputs text from the keyboard or standard input. We can use read to acquire input from the user interactively, but read is capable of more. Most input libraries in any programming language read the input from the keyboard and terminate the string when return is pressed. There are certain situations when return cannot be pressed and string termination is done based on a number of characters received (perhaps a single character). For example, in an interactive game, a ball is moved upward when + is pressed. Pressing + and then pressing return to acknowledge the + press is not efficient.

This recipe uses the read command to accomplish this task without having to press return.

How to do it...

You can use various options of the read command to obtain different results, as shown in the following steps:

1. The following statement will read n characters from input into the variable_name variable:

        read -n number_of_chars variable_name

Consider this example:

        $ read -n 2 var
        $ echo $var

2. Read a password in the non-echoed mode:

        read -s var

3. Display a message with read using the following command:

        read -p "Enter input:"  var

 

 

 

4. Read the input after a timeout:

        read -t timeout var

Consider the following example:

        $ read -t 2 var
        # Read the string that is typed within 2 seconds into
        variable var.

5. Use a delimiter character to end the input line:

        read -d delim_char var

 Consider this example:

        $ read -d ":" var
        hello:#var is set to hello