Re: Q: device(file) permissions for USB

[Greg KH]

On Fri, Dec 07, 2001 at 12:45:21AM +0100, Rene Rebe wrote:
> 
> For usbfs I have to do script-hacking in /sbin/hotplug (I do not know
> how I did it since it is on my brothers box somewhere at the other
> end of Germany ... - but is was some if [$1 = "usb"]; then; chmod
> or maybe even some find /proc -name "xyz..." ...). Especially because
> I only got one parameter ($1 == usb?) the rest was empty. So even
> providing filesnames what got hot-plugged would be nice.

It's there in the DEVICE environment variable.  See
http://linux-hotplug.sourceforge.net/?selected=usb for more
documentation.

So a simple /sbin/hotplug script of:
	#!/bin/sh
	if [ "$1" == "usb" ]; then
		chmod 666 $DEVICE
	fi

would work just fine for your needs.

> Wouldn't it be nicer to use devfs and add this procfs hack for the
> "major dists"? - They could even mount devfs to /devfs and so use
> all the old-way in /dev and only use devfs for the usb stuff.

It's not a procfs hack, it is a stand alone filesystem.  The fact that
you happen to mount it within the /proc filesystem is your option.

The USB developers did not want to force people to use devfs to use USB
devices, and based on the fact that not a single distro is using devfs
(the one that did, now recommends that you disable it) backs up this
choice.

> I do not know why they adapt so slowly to such a cool technology
> anyway ...

See the numerous lkml posts about why this is so.

thanks,

greg k-h