Canon A20 Digicam on FC5

[rnicholas]

I have recently upgraded to FC5. My poor old digicam would not work, although all other USB devices that I have connected so far are OK.
The error message from gThumb suggested possible causes and it turned out that it is a permissions issue. Everything is fine if I use the camera and associated applications as Root.
However, this seems a clumsy way of going about things.
Apparently, I need a udev rule to allow the camera to work from my own ID.
Are you able to help me with this, please? I have looked in the books but I understand udev is something new in FC5.
Many thanks,
Richard

[Tim Watson]

You're right that it's a permissions problem. While the best solution is to become an expert on udev and write a rule for your camera, a workaround that will make all usb devices world writable by default is the following:

use your favourite editor to alter the /etc/udev/rules.d/50-udev.rules file so that the line (near the end of the file)

ACTION=="add", SUBSYSTEM=="usb_device", \
PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev}; printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", \
NAME="%c", MODE="0644"

becomes (you are changing MODE="644" to MODE-"666")

ACTION=="add", SUBSYSTEM=="usb_device", \
PROGRAM="/bin/sh -c 'K=%k; K=$${K#usbdev}; printf bus/usb/%%03i/%%03i $${K%%%%.*} $${K#*.}'", \
NAME="%c", MODE="0666"

What you will have done is to change the mode (permission) of usb devices from 644 to 666 (enabling anyone to read and write the device).

I hope that this helps,

Tim.

[Tim Watson]

I forgot to add that the official method involves using udevinfo when the camera is connected to discover the information needed to uniquely identify it. Then you create your own udev rules file with a low number (typically /etc/udev/rules.d/10-myudev.rules) with a line included that creates a name or symlink for the camera device file. Then you add a line to a new file, typically called /etc/security/console.perms.d/10-mydefault.perms that specifies that whoever is logged in at the console should be the owner of the newly specified camera device file.

The one change to one file in my earlier post is far simpler and ensures that all usb devices will be readable and writable but if you want to ensure that no-one else who is currently logged in to your machine can read and write your camera then the official method outlined above is to be preferred.

All the best,

Tim.