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Debian Packages:
udev
hotplug
A problem that plagued earlier versions of the GNU/Linux kernel was
that each time a USB device (and other devices) was connected a
different mount point would be assigned. This issue was addressed in
the 2.6 kernels using udev
with hotplug. With
udev, naming rules (e.g., in
/etc/udev/rules.d/local.rules) are used to provide stable
names for use in /etc/fstab. Udev
uses
information exported by the kernel drivers to the sysfs filesystem
(usually mounted on /sys) to identify specific devices and to then
associate them with specific names in /dev.
The key to using udev
is with the rules that are defined
to identify and distinguish the different USB devices that may be
connected. A tutorial for writing udev rules is available from
https://www.reactivated.net/udevrules.php.
The first step is to identify the USB device in some way. The
udevinfo command can be used to identify a device path,
which can then be used to identify information about the device on
that path. For example, to identify a specific Flash Memory device
which is recognised in GNU/Linux as a SCSI device, connect the device
and run the command:
$ udevinfo -a -p $(udevinfo -q path -n /dev/sdc)
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The /dev/sdc path here is whatever the dmesg
command identifies. Select some identifying piece of information,
like the product identifier (the line that starts with
SYSFS{product}=), and add that to
/etc/udev/rules.d/local.rules (each rule must be on a single line).
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