udev can not be described fully in this short article. The full release of udev is available at www.kernel.org/pub/linux/utils/kernel/hotplug. It also has been packaged and is available in most Linux distributions that use the 2.6 kernel, including Red Hat Fedora, Gentoo, Debian and SuSE.
A number of helper programs are included in the udev package that can be used in a variety of ways. See the thorough man pages provided with the udev program for more information on how to use them and what they are used for. udev also has the ability to control the permissions on the /dev entries, which is necessary for managing a /dev tree for a multiuser system. See the udev man page for details on how to do this.
If, after all of the documentation has been read and the example configuration files have been studied, anyone has any further questions about udev and how to use it, the linux-hotplug-devel mailing list is the place to turn. It can be reached at linux-hotplug-devel@lists.sourceforge.net, with full archives available to search at marc.theaimsgroup.com/?l=linux-hotplug-devel or news.gmane.org/gmane.linux.hotplug.devel.
LANANA's current device list: www.lanana.org/docs/device-list/devices.txt.
This article is based on the Ottawa Linux Symposium 2002 paper on udev: www.kroah.com/linux/talks/ols_2003_udev_paper/Reprint-Kroah-Hartman-OLS2003.pdf.
udev vs. devfs
For a detailed description of how udev compares with devfs: www.kernel.org/pub/linux/kernel/hotplug/udev_vs_devfs.
If anyone insists on comparing the two even further, read these e-mail threads, in the order in which they happened:
“devfs to be obsoleted by udev?”: marc.theaimsgroup.com/?t=106253338400006. This occurred when devfs was marked OBSOLETE in the 2.6 kernel source.
“devfs vs. udev”: marc.theaimsgroup.com/?t=106553049900002. A very long thread, with occasional flashes of strange behavior by a lot of uninformed people.
“DEVFS is very good compared to UDEV”: marc.theaimsgroup.com/?t=107221474500004. Again, another long thread that really doesn't say anything new, but it allows for those who have not already stated their opinion to do so.
“udev and devfs—The final word”: marc.theaimsgroup.com/?t=107283068500001. A long thread where the udev author gets fed up with the devfs vs. udev rants and tries to put the topic to rest. Unfortunately, this does not seem to have happened.
“removable media revalidation—udev vs. devfs or static /dev”: marc.theaimsgroup.com/?t=107298929800005. A good thread about how udev can try to handle removable media the same way devfs does. Pretty civil thread for the most part.
“devfs vs udev, thoughts from a devfs user”: marc.theaimsgroup.com/?t=107641609100052. Proof, that no matter how hard the udev author tries, some people still want to drag up this thread again and try to beat the topic to death. Nothing is brought up here that has not been discussed in the past threads.