udevedu: udev Event Dispatcher for Unprivileged user
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README.md Update README.md Jun 30, 2015
setup.py

README.md

udevedu: udev Event Dispatcher for Unprivileged user

udevedu is a little tool that allows you to call a Python function on udev events.

Usage

To install, run: sudo pip install . A script named udevedu will be put in /usr/bin. (You can also do pip install --user ., which will put the script ~/.local/bin, and you need to take care to add that to your $PATH.)

Put hooks in ~/.config/udevedu/hooks, which will be created the first time udevedu is invoked. Some sample hooks (read: hooks used by me, xiaq) are contained in the hook/ directory of the repository.

Anatomy of hook scripts

Three functions are looked for in hook scripts: init, check and react. They are all optional.

init function is called after udevedu has started and collected all hook scripts.

check and react is called when a udev event is received. If check doesn't exist or returns a true value, react is called. Both are passed two positional arguments, action and device which come from pyudev.Monitor.receive_device.

Notes:

  • check is actually not necessary, but it would save you one level of indentation.
  • check and react are called off the main thread, so that they may block.

Why not just write udev rules?

Because udevedu runs as an unprivileged user in arbitrary environment - e.g. from your WM script so that it can call xset, notify-send etc.

Other small bonuses:

  • You don't need to learn yet another arcane configuration language - the information of the event is available as easy-to-use pyudev objects
  • Hook functions are executed in separate threads, so that one blocking hook doesn't affect other hooks
  • It's also much easier to experiment and debug - just put from pdb import set_trace; set_trace() anywhere in the check or react function.

TODO

  • Automatic reload of hook scripts

  • pyudev.Monitor.receive_device is deprecated, should use new interface; maybe also use the asynchronous pyudev.MonitorObserver?