To make sure the usbtmc devices have lax permissions, I do the following.
First, I create a group called “usbtmc” and add myself to the group
groupadd usbtmc gpasswd -a awebster usbtmc
Log out and log in again to get the permissions set correctly.
Next, you’ll have to edit some udev rules in
/lib/udev/rules.d/51-usbtmc.rules. On Debian systems this should be put in
and add the following line to one of these files
# this is the general rule that covers usbtmc devices KERNEL=="usbtmc/*", MODE="0666", GROUP="usbtmc" KERNEL=="usbtmc[0-9]", MODE="0666", GROUP="usbtmc"
This will make it such that every time there’s a
/dev/usbtmc[0-9] device, it will belong to the group
usbtmc and have 0666 permissions.
On Debian you have to reload the rules:
udevadm control --reload-rules udevadm trigger
Unplug and re-plug the device. Verify that it works
ls -la /dev/usbtmc0 crw-rw-rw- 1 root usbtmc 180, 0 May 5 13:09 /dev/usbtmc0
You should have free reign to the device now.