In some cases, Unix tests involve more CLI usage as compared to MS-Windows based applications.
Unix has an extensive CLI (Shell), which can be used to perform some activities instead of using the GUI (For someone familiar with these CLI commands, the usage is far more faster)
Linux share very similar CLI.
One should learn this CLI in order to test over Unix / Linux.
But there are also GUI applications created in Unix that are also tested like Windows applications. I've used some GUI shells for running Unix commands for testing which is definitely not my personal preference. I find I spent too much time learning the GUI and apply my commands and would rather just type out the characters of the commands themselves.