#+TITLE: socket-based command runner #+TAGS: utilities #+AUTHOR: Ed Langley ** Introduction Run a command everytime a line is written to a unix socket, passing the line written as the last argument to the command. Useful in an =after-save-hook= in emacs to run tests after the buffer is saved. Unlike file-watchers, this allows more precise control of when the tests are run, reducing the amount of time spent configuring ignore files and waiting for spurious reruns. ** Building Choose either building with zig: #+BEGIN_SRC zsh :results output :post proc zig build --verbose #+END_SRC Or nix: #+BEGIN_SRC zsh :results output :post proc nix build github:fiddlerwoaroof/sigexec #+END_SRC One can also run the flake's default app like: #+BEGIN_SRC zsh :results output :post proc nix run github:fiddlerwoaroof/sigexec <socket> <command...> #+END_SRC ** Usage #+BEGIN_SRC zsh rm /tmp/jest.sock ; $OLDPWD/zig-out/bin/zig-test /tmp/jest.sock npx jest -- #+END_SRC ** Full-stack example: *** In one terminal: #+begin_src zsh % nix run github:fiddlerwoaroof/sigexec /tmp/bar.sock echo NOTICE ME: input: # output: # warning: listening at /tmp/bar.sock # # NOTICE ME: input: 4 #+end_src *** In another terminal: #+begin_src zsh # in another terminal: % echo 4 | socat - unix-connect:/tmp/bar.sock # ACK! #+end_src #+NAME: proc #+BEGIN_SRC elisp :exports none (defun fix (fn inp) (cl-loop for old = inp then new for new = (funcall fn inp) until (equal new old) finally (cl-return new))) (s-join "\n" (funcall (fwoar/over (lambda (it) ( (lambda (v) (s-replace-regexp " \\(--\\|#\\)" " \\\\\n \\1" v)) (s-replace-regexp "/nix/store/[^/]*/\\(.* \\)" "/nix/.../\\1" (s-replace "/Users/edwlan" "~" it))))) (s-lines (s-trim *this*)))) #+END_SRC