 Hello and welcome you ever Enter a shell and then go a shell deeper and shell deeper and you have these children's shells and these parent shells and you have completely Lost track of how many shells deep you have gone Well, there's a variable fault for that a system variable I should be able to say echo dollar sign sh for shell LVL again all capital And that will tell me how many shells deep I am so I'm 18 shells deep I can run that again, and now I'm 19 shells deep I can run it again, and now I am 20 shells deep and if I exit out of one I can run it again, and you can see I'm 19 if I exit exit exit I can run it. I can see how many levels deep I'm in which could be helpful and It also works with their shell so I can go into my z shell here and I can run that same echo dollar sign shell level Variable, and you can see I'm this may shells deep and I can go again and again and again Again, and I can run that same variable Echoing it out, and you can see it on 21 levels deep This could be useful again if you don't know how many deep you are and you're just curious You could do that, but I could also see this being useful if you were to Put something in a script or your shell settings that because sometimes you're a few shells deep and you start exiting out and You don't want to exit all the way out in some cases And you don't know what level you're at and you might exit too far and completely close your terminal You could theoretically I haven't tried this But you should be able to alias your exit command to check that variable and give you a warning if you are at the Top-level shell. Anyway, that's just thought I found this interesting I'm just looking through system variables here, and that was what I found interesting. So again I'll sign shell level And I can see that I am 11 deep now. Whoops. I did not mean to go into it Okay, for most of you it's probably useless, but it's just interesting information It could be helpful and again I could theoretically see somebody putting an alias in there for their exit command that checks that variable And if it's at the one the you know the top-level Shell it will give you a warning so you don't accidentally close your terminal if you don't want it to anyway Thank you for watching. I hope that you have a great day