Device::USB::FAQ 0.21

Device::USB::FAQ Perl module contains Frequently Asked Questions for Device::USB.

This is an attempt to answer some of the frequently asked questions about the Device::USB module.

Which platforms does Device::USB support?

Device:USB supports any platform that libusb supports. This list currently includes Linux, FreeBSD, NetBSD, OpenBSD, Darwin, and MacOS X.

There is a port of the libusb library to the Windows environment called LibUsb-Win32. Because I dont have a development environment for testing this library, Device::USB does not yet support this library.

Do I have to use Device::USB as root?

By default, access to the USB devices on a Unix-based system appear to be limited to the root account. This usually causes access to most of the libusb features to fail with a permission error.

Using the Device::USB module as root avoids this feature, but is not very satisfying from a security standpoint. (See the next question for more options.)

How do I enable use of Device::USB as a non-root user?

Some of the attributes of USB devices are available to non-root users, but accessing many of the more interesting features require special privileges. According to the libusb source, the open() function requires either device nodes to be present or the usbfs file system to be mounted in specific locations. Those places in order are:

1)
/dev/bus/usb - pre-2.6.11: via devfs / post-2.6.11: via udev
2)
/proc/bus/usb - usbfs

Look in both locations on your system for which of these two methods your libusb will use.

No matter which method your system uses, you will probably want to create a separate group to control access. Run this command to add a system group:

addgroup --system usb

or

groupadd --system usb

You can then add users to that group to allow access to your usb devices.