Remap ctrl to caps lock only when emacs is running, on linux

In windows I did this using an AutoHotKey script that chekced if an emacs' instance was running, and if so, it would make tha caps lock a ctrl key, but in linux I have no idea how to do it. I know how to remap a key for the whole system, just not for only an emacs instance... any idea?

Depending on your Desktop Enviorment, you will be able to set commands on startup. You only really need to put '''setxkbmap -option ctrl:swapcaps''' as a startup command asuming you're using Xorg.

yes I'm using xorg with dwm. I just use stxkbmap in the .xinitrc? Besides, it's still going to apply this change system-wise, which is better than nothing, but not ideal

Oh, a fellow wm autist I see. I remember dwm being a little bit of a pain to set autostart applications, I think there was a patch that executed a script on startup. And by the way, the setxkbmap is not global, just session-wide in the current user (you don't need to call 'sudo' for it), so no worries irreversably fucking up your keyboard.

In the distant past I remapped my Caps Lock key to Esc. I think I was experimenting with hard drugs and vim at the time.

There are several window managers, which are capable of remapping keys on a per application basis (StumpWM, FVWM, EXWM and others). On StumpWM the feature is called`define-remapped-keys`. On FVWM the module implementing this functionality is called `FakeKeypress`. I do not know if dwm implements something like this. There might be programs which are also capable to do this, but I could imagine they pose a security risk, since they have to intercept all key input.