I'm about to hold a course for learning Linux. I'd like the participants to see what keys and key combinations I press. Is there anything like Mouseposé for Linux?
I've used key-mon and I'm really impressed with it. It does exactly what you want without eing a nuisance. The only let down, is that if you keep holding any of the modifiers down, e.g. control, then the consecutive key combinations (ctrl + x, then ctrl + s) will not display the control key as being pressed down.
For running e.g. a tutorial on Emacs navigation, this somewhat of a let down. Apart from that, I find key-mon great.
Key-mon is a little python program I found recently that seems to do exactly what you want. I have not tried it myself yet, so I can't comment on how well it works.
screenkey is "a screencast tool to display your keys". It allows a fair amount of customization and has worked really well for me personally. It does not have the same issue as key-mon when it comes to sequential combination including modifiers, instead it correctly displays the modifier that is being held down with each subsequent key press.