Talk:Udev

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Revision as of 16:23, 10 May 2016 by Netadmin (talk | contribs) (Noticed udev hotplug example assumes xauthority is in home directory, but display mangers may differ.)
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usbtiny extra udev rule?

In the udev rules for usbtiny, there are 2 rules listed. Howver, adding the second one to my udev rules resulted in me not an "rc=-1" communication error when I tried to use my usbtiny. When I commented out this rule:

"SBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="0479", GROUP="users", MODE="0666"

everything worked fine. Not sure what the root of the issue is, but this rule makes the usbtiny programer unusable. -- Ssalenik (talk) 04:09, 6 March 2012‎

About udev rules

udevadm info -a -n [device name]

and

udevadm info -a -p $(udevadm info -q path -n [device name])

gives the same output but the latter is recommended by some Khampf (talk) 20:57, 5 February 2013 (UTC)

Use of 'uaccess' instead of GROUP and MODE?

Bug openobex - relies on non-existing group plugdev, conflict with systemd made me rethink the rules I have been using for Logitech_Unifying_Receiver.

Currently, the following rule is taught to the user:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="1781", ATTRS{idProduct}=="0c9f", GROUP="users", MODE="0666"

What about changing it to:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="1781", ATTRS{idProduct}=="0c9f", TAG+="uaccess"

As a developer note, Ubuntu versions before 13.04 Raring needs TAG+="udev-acl" instead of uaccess. For compatibility with modern and legacy systems:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="1781", ATTRS{idProduct}=="0c9f", TAG+="uaccess", TAG+="udev-acl"

References:

Lekensteyn (talk) 10:16, 6 June 2013 (UTC)

Printers

Udev#Printers:

If you use multiple printers, /dev/lp[0-9] devices will be assigned randomly on boot, which will break e.g. CUPS configuration.

I don't use multiple printers, but doesn't system-config-printer handle this automatically? If so, a tip could be added. --Alad (talk) 08:38, 28 June 2014 (UTC)

It might, unfortunately its gtk3 dependency discouraged me from even trying... -- Lahwaacz (talk) 09:01, 28 June 2014 (UTC)

Additional detail on "Execute on VGA cable plug"

Not sure if it belongs in this wiki, but worth noting in the hot plug example that the Xauthority may be located elsewhere based on display manager.

This is the example:

KERNEL=="card0", SUBSYSTEM=="drm", ENV{DISPLAY}=":0", ENV{XAUTHORITY}="/home/username/.Xauthority", RUN+="/usr/bin/arandr"

If you have GDM and you check the Xauthority location as follows:

$ env | grep XAUTHORITY
XAUTHORITY=/run/user/1000/gdm/Xauthority

You will see the file is not in a home directory and you need to tweak the ENV{XAUTHORITY} accordingly.

Not sure if this bit of information is useful in the wiki or consider overly specific for this use case. Netadmin (talk) 16:22, 10 May 2016 (UTC)