libudev advice needed

Question

I am embarking on a programming project that will need to confirm device identity of removable media (e.g. usb thumb drives) before it will go on to do a bunch of other cool stuff.

Some friends of mine pointed me towards using the Serial Number, and preliminary testing using the udevadm command indicates that this should work. I did some additional checking and it appears that if I can get the software working with libudev then it should (minimally) compile on ubuntu, slackware and gentoo, which would be a really nice benefit.

So I used bing to find a tutorial and got the Signal 11 site (http://www.signal11.us/oss/udev/) it's a very well-written tutorial. It actually seems to have everything I need. I download the code. Fix a couple of platform-specific bugs and then compile. BOOM! Gcc compiles without errors. So far so good.

But when I try to run it, it kicks up a couple of bugs, and I realize that I need to read some more tutorials so that I can understand libudev well enough to fix the bugs, and to turn out working software. Problem is that there really ISN'T any other tutorials (that I can find) and the kernel.org site that is the (only known?) site of the library documentation is down after a recent server compromise.

I considered just issuing udevadm directives to system() and then parsing results, but that's a really hackish way to put software together, and I am planning on releasing this to the community when I'm finished writing.

So how best for me to learn libudev??

Maciej · Answer 1 · 2017-07-12T20:24:13.850

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libudev is quite simple library. After reading library you've mentioned and using API documentation (site should be soon up) I was able to get what I wanted. udevadm is great help, after issuing # udevadm info --query=all --name=/path/to/dev you'll get all information that udev has about this device and what's more important, these are parameters used in property functions (e.g. udev_device_get_property_value(device, "ID_VENDOR")). So best way to learn libudev is to start using it with help of signal11 tutorial, API documentation and udevadm informations.

EDIT: libudev is currently part of systemd - documentation is available as manual pages - https://www.freedesktop.org/software/systemd/man/libudev.html#

edited Jul 12 '17 at 20:24

answered Sep 15 '11 at 18:21

Maciej

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It would be awesome to see some references in this answer. – karlphillip Feb 09 '12 at 19:32
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@karlphillip tutorial: http://www.signal11.us/oss/udev/ API: http://kernel.org/pub/linux/utils/kernel/hotplug/libudev/ – Maciej Feb 10 '12 at 08:41
Sadly, the link to the API reference is broken. :-( – Andrew Falanga Dec 07 '16 at 15:11
Link still broken. – Zimano May 01 '17 at 09:40
@AndrewFalanga libudev is now part of systemd, documentation available as manpages: https://www.freedesktop.org/software/systemd/man/libudev.html# – Maciej Jul 12 '17 at 20:26

score 0 · Answer 2 · answered Feb 19 '23 at 01:17

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For those looking in 2023...

As Maciej pointed out, libudev is now a part of systemd.

According to:

https://www.freedesktop.org/software/systemd/man/libudev.html#

...this library is supported, but should not be used in new projects. Please see sd-device(3) for an equivalent replacement with a more modern API.

Documentation for sd-device:

https://www.freedesktop.org/software/systemd/man/sd-device.html#

answered Feb 19 '23 at 01:17

Fermi-4

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The documentation on "sd-device" is right now very very minimalistic. I wonder, if the libudev-specific documentation can be used as it is stated that sd-device is an "equivalent" API... – Degoah Apr 12 '23 at 11:46

libudev advice needed

2 Answers2