Learn Linux Shell Scripting - Fundamentals of Bash 4.4

Input redirection

Two other famous special devices, /dev/random and /dev/urandom, are best discussed in tandem with the next bit of redirection: input redirection.

Input normally comes from your keyboard, passed through by the Terminal to the command. The easiest example for this is the read command: it reads from stdin until it encounters a newline (when the Enter key is pressed) and then saves the input to the REPLY variable (or anything custom, should you have given that argument). It looks a bit like this:

reader@ubuntu:~$ read -p "Type something: " answerType something: Somethingreader@ubuntu:~$ echo ${answer}something

Easy. Now, let's say we run this command non-interactively, which means we cannot use a keyboard and Terminal to supply ...