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Sometimes Lisp hangs due to an infinite loop, making the whole of Emacs unresponsive, so it can't process any input, C-g included. So, I was hoping for there to be a way to maybe send it an emergency call from the outside, which would interrupt the Lisp interpreter, but would not kill Emacs altogether. I've experimented with sending some signals by means of
kill -s <signal>, but Emacs seems to quit no matter what signal it is.