I can't understand why people are quite happy to explore parts of their OS by GUI, yet immediately become "scared" to do the same in the CLI .. you can just as easily screw your system either way .. but once you understand a handful of commands for the CLI (and how to understand the documentation for what you don't know) you may find fixing things a little easier

(oddly, the CLI tends to be better documented .. once you learn how to read it)
Sure, you'll make mistakes (hopefully not big ones) .. but isn't that the way we learn .. and that equally applies to the GUI.
I found the easiest way to pick up the command line was every time you see a command given on a forum that you don't understand .. use the man pages to try to work it out .. some of it eventually sinks in

So if you see say
You'd look at:-
and see what the "-l" option does.
"|" means pipe (redirect) the output to the next command .. which is "grep" .. so then look at:-
to see what it's going to do with the output from "dpkg -l"
and you'll find that:-
"
dpkg -l" will list the current install status of ALL packages you have installed, but it would be a long list .. so instead of printing it ALL to screen, the output was piped (
|) to the "
grep" command which will search that output for all lines containing the string "
flash" which are then printed to screen.
So whoever wrote the command was looking for the current installation status of all packages containing the string "flash" .. or put another way, what "flash" packages you have installed.
Once you get your head round how to understand the man pages, it all starts to fall into place pretty quickly.
FYI, you can exit a man page and return to a normal $ prompt by hitting the "Q" key.
Here endeth the lesson for today

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