/usr/lib/perl5/Device/USB/FAQ.pod is in libdevice-usb-perl 0.36-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 | =head1 NAME
Device::USB::FAQ - Frequently Asked Questions for Device::USB
=head1 SYNOPSIS
perldoc Device::USB::FAQ
=head1 DESCRIPTION
This is an attempt to answer some of the frequently asked questions about
the Device::USB module
=head1 QUESTIONS
=head2 Which platforms does Device::USB support?
C<Device:USB> supports any platform that C<libusb> supports. This list
currently includes Linux, FreeBSD, NetBSD, OpenBSD, Darwin, and MacOS X.
There is a port of the C<libusb> library to the Windows environment called
C<LibUsb-Win32>. Because I don't have a development environment for testing
this library, C<Device::USB> does not yet support this library.
=head2 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
C<libusb> features to fail with a permission error.
Using the C<Device::USB> module as root avoids this feature, but is not
very satisfying from a security standpoint. (See the next question for
more options.)
=head2 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 C<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:
=over 4
=item 1)
F</dev/bus/usb> - pre-2.6.11: via devfs / post-2.6.11: via udev
=item 2)
F</proc/bus/usb> - usbfs
=back
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.
=head3 DEVFS / HOTPLUG
TODO
=head3 UDEV
If you use Debian/Ubuntu, look in the F</etc/udev/permissions.rules> file.
If you want to allow global access to all usb devices, make this change:
Change this:
SUBSYSTEM=="usb_device", MODE="0664"
To this:
SUBSYSTEM=="usb_device", MODE="0664", GROUP="usb"
After you reboot, all usb devices will inherit the mode and group specified.
If you want to only change permissions for certain devices, you can add this
on one line and adjust the product and vendor IDs:
SUBSYSTEM=="usb_device", GROUP="usb", \
SYSFS{idVendor}=="1234", SYSFS{idProduct}=="1234"
=head3 USBFS
The usbfs defaults to root as the user and group. This can be changed in the
F</etc/fstab> by adding the following on one line:
none /proc/bus/usb usbfs noauto,\
listuid=0,listgid=118,listmode=0664,\
busuid=0,busgid=118,busmode=0775,\
devuid=0,devgid=118,devmode=0664\
0 0
The value C<118> in the above should be replaced with the group id of
your usb group (created above). The list* values are to allow listing
devices, the bus* is to control access to the bus directories and the
dev* values control access to the device files. This approach does not
allow the kind of granular permission that the udev approach gives, so
it is all or nothing unless permissions are changed programmatically.
If your F</etc/fstab> file already has a line for F</proc/bus/usb>, add the
options above to the line that is already there rather than adding the
new line. For example, you would change
usbfs /proc/bus/usb usbfs noauto 0 0
to
usbfs /proc/bus/usb usbfs noauto,\
listuid=0,listgid=118,listmode=0664,\
busuid=0,busgid=118,busmode=0775,\
devuid=0,devgid=118,devmode=0664\
0 0
Once again, this needs to be all on one line with the C<\> characters
removed.
=head1 SEE ALSO
Device::USB and the C<libusb> library site at
L<http://libusb.sourceforge.net/>.
=head1 AUTHOR
G. Wade Johnson (gwadej at cpan dot org)
Paul Archer (paul at paularcher dot org)
Houston Perl Mongers Group
=head1 ACKNOWLEDGEMENTS
Thanks go to various users who submitted questions and answers for the
list. In particular, Anthony L. Awtrey who contributed the first FAQ answer.
=head1 COPYRIGHT & LICENSE
Copyright 2006-2013 Houston Perl Mongers
This document is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=cut
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