I'm running Arch Linux on my server, and I need to let users of the group usb access my weather station.

Here's my rule: /etc/udev/rules.d/usb-70.rules

SYSFS {idVendor} == "1941", SYSFS {idProduct} == "8021", MODE = "0666", GROUP = "usb"

Users in the usb group still can't see the device (permission denied). The Vendor and Product ID is confirmed correct, and I've rebooted 50 million times to no avail. Anyone have any ideas?

  • Could a later rule be overriding yours? Is this the complete file listing? What other files come later (in lexicographic order) in /etc/udev/rules.d? Jan 28, 2011 at 20:05
  • 3
    Run udevadm monitor to watch udev events, and then re-plug your USB device (or use udevadm trigger).
    – ephemient
    Feb 17, 2011 at 6:40
  • Or use udevadm test /sys/bus/usb/devices/1-2:3-4 where the path locates your USB device (this path will depend on where it's plugged in, but that's only for debugging). Apr 22, 2011 at 21:15

2 Answers 2


SYSFS has been replaced by ATTR, at least in the udev version used by Debian. So try this instead of your rule:

ATTR {idVendor} == "1941", ATTR {idProduct} == "8021", \
  MODE = "0666", GROUP = "usb"
  • I fail to see the difference
    – XTL
    Oct 10, 2012 at 8:24

Can you add SUBSYSTEM=="usb" to the beginning of that rule?

If the version of udev is old enough (no idea what Arch uses, sorry), it might be BUS=="usb", instead.

What are the permissions on the device?

If none of that helps, can you show us the udevadm info output for that device?

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