There are a lot of errors in the Command Line course, both in the lesson text and how the tasks respond to what is input. I can progress fine, but I know these issues will confuse many people.
The task completion seems to check for the right command somewhere in the terminal, even if it was several lines back, this leads to lots of unneeded error messages when the task jump ahead of where you actually are in the lesson. There also seems to be some directory issues where the task completion requirement does not match with what is actually required to progress in the task.
Also, I think it would be beneficial to make it obvious that this is for Unix based systems and only some commands will work in Windows.