In this video we'll talk a little bit more about the systemd UDFD plug and Play manager.
So systemd UDFD is a standard component on Linux distributions and it ensures
that hardware that is plugged in is enabled with the appropriate properties.
In order to do so, it processes rules and you can find these
rules in userlib UDEV rules d and in etcudevrules dash you can define
exactly what you want to happen when hardware device is plugged in.
Now the user lib UDEV directory contains the standard rules which are installed from packages and should not be modified. If ever
you want to modify, you will put your rules in etc UDEV rules D. But for this course, that's a little bit
too advanced, so let's not do that. One thing that I do want to show you is UDEV ADM monitor.
That's actually a very convenient command that helps you to trace what exactly is happening when
you are plugging in a device. So let me show you UDAV ADM monitor I'm starting
with sudo UDEV ADM monitor and that is going to wait. For hardware events to happen.
If nothing is happening, you can wait. For a long time.
Now let me plug in a USB thumb drive.
Here. As I'm using virtualization, I need to tell my virtualization software what to do with it.
I want it to connect to my CentOS machine. There we go. Okay.
There you can see the USB thumb drive being initiated. The interesting thing is
that you can. Trace the entire procedure. Like here for instance, where you can.
See that the exfat module is loaded.
If you scroll up, you can also see that it has initialized the USB thumb drive as a
device. SDA SDA One more interesting if ever you plug in a USB device and nothing is happening,
well, here you can see what has happened and that might help you in the troubleshooting.
So UDEV ADM monitor works for plugging in, but it also works if you
unplug the device. There you can see the different hardware events are happening.
If you are wondering what is this devices PCI000 and so on,
that is the hardware interface that you find in the sysval system.
So if you really want to go deep, all of this relates to files in the
sys file system because in the end sys is what is used for hardware management.