# Hello World from the Command Line On this tutorial we are going to learn about the `echo` command in Bash This command prints to the screen whatever you send it. It's as easy as: ```{.bash .cb_test} @learner $ echo "hello world" @learner hello world ``` The great power of Unix is the pipe `|` the idea to connect programs that weren't made to be connected. so if we connect `tr` to our previous command we will get: ```{.prysk .cb_test} @learner $ echo "hello world" | tr '[:lower:]' '[:upper:]' @learner HELLO WORLD ```