[BRLTTY] udev with systemd

[Mike Gorse]

On Fri, 8 Jan 2016, Mike Gorse wrote:

>> Please test the latest commit to verify that it's correct.
>
> Tested. Yes, that works.
>
>> Is there something we can do on remove in order to stop the service?
>
> I asked a colleague who is more familiar with systemd than I am, and he 
> pointed me to this link:
>
> http://unix.stackexchange.com/questions/63232/what-is-the-correct-way-to-write-a-udev-rule-to-stop-a-service-under-systemd
>
> However, when I run
> systemctl list-units --all --full |grep .device
> I get this for the Brailliant:
> dev-brltty-auto\x2dusb:25000072.device 
> loaded    active   plugged   Brailliant_40
> dev-bus-usb-003-039.device 
> loaded    active   plugged   Brailliant_40
>
> So it appears that I need a fixed device name that systemd could bind to for 
> any Braille display. I've just tested having the udev rules file create a 
> symlink called "braille" and have systemd bind to it, and now it unloades 
> when I remove the display. Patch attached.

On second thought, that patch isn't right--it makes systemd require the 
device in order to load brltty, which will break for a serial or a 
bluetooth device.