Some Linux commands interact with the user input through the standard input (which is your keyboard by default). For example, the read command reads input from the user and stores it in a variable. For example, you can run the command read weather:
elliot@ubuntu-linux:~$ read weather
It is raining.
It will then wait for you to enter a line of text. I entered the line It is raining. and so it stored the line in the weather variable. You can use the echo command to display the contents of a variable:
elliot@ubuntu-linux:~$ echo $weather
It is raining.
Notice that you have to precede the variable name with a dollar sign. The read command is particularly useful in shell scripts, which we will cover later on. Now notice I wrote the line It is raining. using my keyboard. However, I can redirect standard input to come from a file instead using the less-than sign <, for example:
elliot@ubuntu-linux:~$ read message < mydate.txt
This will read the contents of the...