joshkunz / uecron

A cron-like program for executing scripts when device status changes occur.

UEcron

UEcron is a cron-like that allows you to execute a given program when devices are added, changed, or removed. This program offers a simpler standalone approach as opposed to the integrated complex solutions like udev rules. I originally created this project to monitor virtual devices created in network namespaces (something that cannot easily be done with udev).

This project directly accesses the kernel's "uevent" system for device notifications and does not rely on udev in any way.

Basic usage

uecrond --config <path to uetab>

Which will start uecron listening for device events. When a device event occurs that matches a line in the supplied "uetab" the associated command will be executed. The "uetab" format follows the standard cron layout:

# Device path (everything after /sys)   action          command
/devices/virtual/net/somebr0            add,remove      do_something_great

An example uetab is located in the repository

The set of available actions is add, remove and change. Any additional that was in the event is supplied to the command as environment variables. The exact set of environment variables changes depending on the event type and type of device, but the variables will always be prefixed with UECRON_.

Options

usage: uecrond [-h] --config CONFIG [--foreground]

optional arguments:
  -h, --help            show this help message and exit
  --config CONFIG, -c CONFIG
                        Path to configuration file
  --foreground, -f      Run in the foreground instead of daemonizing.