Using kmsgrab and triggerhappy for full-screen screenshots

roslof

In the past we could use raspi2png for screengrabs, but the tech is obsolete for modern OSes. Would like to combine a modern capture tool with triggerhappy for keyboard-triggered screen captures using the method in the thread linked above.

In 2025, it seems that kmsgrab might be a good alternative with Bookworm, but it needs sudo/root access, which may prohibit it from running in a script. Wondering if there is a way to run kmsgrab in this fashion, or if a different tool would be required.

I've already configured a triggerhappy conf file and it tries to run kmsgrab with a filename param, but it definitely needs sudo, which I think is a non-starter.

Is there a clever way to make this work?

Cheers!
-Ros

EDIT: I'm realizing that this may be a Pi 5 / Bookworm issue and thus is probably not ready for this forum.

Lolonois

You may succeed with giving the kmsgrab system admin capabilities, it does no longer require explicit sudo then.

sudo setcap cap_sys_admin+ep /path/to/kmsgrab

https://linux.die.net/man/8/setcap
https://linux.die.net/man/3/cap_from_text
https://man7.org/linux/man-pages/man7/capabilities.7.html

I did not debug to the end, but I strongly assume at some point DRM hits this method, which bails out with -EACCES ("Operation not permitted") when privileges are not met.