>By default the echo command takes the input (standard input or stdin) from the keyboard and returns the output (standard output or stdout) to the screen.

This isn't right is it? Echo doesn't read anything from stdin:

    echo <<< HelloWorld
    

Does this command makes any sense?

    $ ls | grep *.txt /tmp
    grep: /tmp: Is a directory

I found the whole text-fu section quite confusing...