As others have said, you could install and use a desktop distribution and use it much like Windows and never end up entering anything to a command line. I guess another parallel is if you use Windows, you may also never use the command line, but there are rare occasions where that can happen and usually it's either because you were recommended or instructed to do so, or you learned enough about the system to eventually use it for more technical reasons than a casual user.

And then there are cases where you do more with Linux besides use it as a desktop. For instance a server, or maintain systems for others, or write code and scripts. In those cases, you'd find that you'd use the command line very much. Similarly the subtle differences between ">" and ">>" would be important if you wished to do something in a script I prefer, which is to use those to re-direct to a log file and also have the log file be newly created each time the script runs. Some scripts I have are invoked randomly as needed and each time they may be doing a repetitive task, but still unique to the time I'm running it. Therefore the first write to my log file will cause any existing log file to be replaced, and then following writes to the log file will append versus overwrite.

I did have the impression that Linux seemed to be mostly used for servers. If used in a server situation, is the command line version or the GUI version? I was thinking command line...

It could be either. Most of the time servers have no keyboard, monitor, or mouse attached, so a GUI is just a waste of space and is not installed. That doesn't mean it can't be installed though.

I think it is safe to assume that most machines used exclusively as some kind of server will likely use mainly the command line.
Last I saw Microsoft are heading that way a little too offering a command line only version and making a lot of tasks, such as creating Exchange mailboxes, much easier on the command line that through the GUI.