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? – Gilles Jan 28 '11 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 '11 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). – Gilles Apr 22 '11 at 21:15

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?


SYSFS has been replaced by ATTR, at least in the udev version used by Debian.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 '12 at 8:24

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