On Fri, 06.01.12 14:55, Richard Shaw (hobbes1069@xxxxxxxxx) wrote: > Ok, I didn't know how to make the subject any shorter, but there's a > big BUT in this, but (hehe) first a summary. > > I have a user of MythTV that has capture devices which require a > firmware be uploaded. As a consequence, the /dev paths are not always > created by the time mythbackend tries to start. A solution to this is > to create a mythbackend.path unit file which will wait for the devices > to be created, BUT, they occasionally fail to initialize and the path > unit file doesn't seem to have a timeout option (or option for what to > do once the timeout is reached). > > A partial solution would be to use a timer unit file, but it too > doesn't do quite what I need. It doesn't appear that I can wait for > the start of one unit file (mythbackend.path) while starting a > different unit file (mythbackend.service) once the timeout is reached. > > I could use the same 'After=...' as I have on the main service file > which would approximate the same startup time, but that's rather > hackish. I am assuming that having two unit files (a path and a timer) > trying to start the same service isn't an issue and that the first one > wins. > > Below is the entire message I was sent with his solution which is even > more complicated than what I'm proposing, but appears to work. Drop a udev rules file into /lib/udev/rules.d (if this is for a package) or /etc/udev/rules.d (if this is just a local installation) where you match the device and add the systemd tag to it: SUBSYSTEM=="foobar", SOMEMOREMATCHESHERE, TAG+="systemd" (Replace foobar with the subsystem name of your device and SOMEMOREMATCHESHERE with some sensible matches that identify your device uniquely). That will result in a .device unit to show up in systemd whenever the device is available, named after the /dev path (or /sys path if it doesn't have a device node). Then, you can add the following to your service: Wants=dev-waldo.device After=dev-waldo.device (Assuming your device is called /dev/waldo) And that should do the job. Lennart -- Lennart Poettering - Red Hat, Inc. -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
