parallel port setup in this brave new udev world?

[Harald Hoyer]

Michael Wiktowy wrote:
> I have a parallel port scanner that has traditionally been pointed
> at /dev/parport0 (call me a savage if you want ... but it hasn't died
> yet so I haven't bought a newfangled usb one)
> 
> However, that device is nowhere to be found so I cannot use the udev
> permissions file to set the permissions on the device so that regular
> users can use xsane (and avoid the scolding for using xsane as root)
> 
> Oddly enough, root can run xsane fine eventhough there is no device for
> it to find ...
> 
> Three questions that I hope someone can enlighten me on:
> 
> 1) Is there a missing
> KERNEL="parport*", NAME="%n", SYMLINK="parport%e"
> line in the rules file for udev?


This is nonsense and would create:

/dev/0
/dev/parport -> /dev/0
/dev/1
/dev/parport1 -> /dev/1


If there is no rule, udev takes the kernel name... just load the ppdev module

> 
> 2) Why is it that root can find the parport device fine eventhough it
> does not seem to exist? i.e. the scanner is detected and runs fine while
> regular users can't find the scanner.


$ ll /dev/parport0
crw-rw----  1 root lp 99, 0  4. Okt 11:16 /dev/parport0

$ ll /dev/lp0
crw-rw----  1 root lp 6, 0  1. Okt 16:18 /dev/lp0


Maybe it accesses the scanner through /dev/lp0. Normal users do not have permissions for that file.

> 
> 3) How does one cause udevd to reread and reapply the rules/permissions
> in the etc files other than rebooting? "service udevd restart", "udevd",
> "udevstart" all give me no joy.

/sbin/udevstart _should_ do the job.