add optionto set the docker 'device' command line argument

[djpnewton]

Not sure how to make a test for this.

Devices like /dev/null are already present in the docker container. So you need a new device present on the machine to share with docker.

You could do something like this https://stackoverflow.com/questions/23135589/create-dev-fakedevice-supporting-read-write-and-ioctl to make a new character device but you would need root to install it.

Would docker in docker help here?