I've done a bit of research on this subject and am turning up blanks. There seem to be implementation-dependent ways of doing Unix signal handling in Common Lisp, but is there a package that gives a cross-implementation way of doing signal handling?
I would mainly like to listen for SIGINT and do a graceful shutdown in my app. I'm using Clozure CL 1.7 on linux...like mentioned, it would be great for a package for this, but if I have to resort to implementation-specific code, that's fine.
I'm also not completely married to using SIGINT (although it's ideal). I can use another signal if needed.
If this is going to be messy, does anyone have any other suggestions for gracefully shutting down a lisp app from outside the app? One idea I had is to create a file the app monitors for, and if it detects the file, it shuts down...kind of hacky, though.
Thanks!
I can't find a general library for signal handling either. However, Slime implements "create a custom SIGINT handler" for most Lisp implementations. By looking at the CCL case of that code, I found ccl:*break-hook*. ccl:*break-hook* is not in the documentation, but the commit it was introduced in is located here.
This trivial example code works on my system (CCL 1.8, linux x86):
(setf ccl:*break-hook*
(lambda (cond hook)
(declare (ignore cond hook))
(format t "Cleaning up ...")
(ccl:quit)))
After this code is entered into a non-Slime REPL, sending SIGINT will cause the program to print "Cleaning up ..." and exit.