USB on Linux Systems

You are likely to get permission errors when trying to access the USB port on Linux systems. It is usually required to create a udev rule for your device in /etc/udev/rules.d/ with a name that ressembles the device, for example, 99-elgin-rm22.rules for Elgin RM-22 portable thermal printer:

# Elgin RM-22 udev rules
SUBSYSTEM="usb", ATTR{idVendor}=="20d1", ATTR{idProduct}=="7008", MODE="666"

If you need more information about your device, try lsusb -d 20d1:7008 -v.

References

• PyUSB library (see also their wiki pages)
• Writing udev rules
• An introduction to Udev: The Linux subsystem for managing device events