Where did udevmonitor go?

In case you’re looking for the “udevmonitor” program on the Intrepid Ibex version of Ubuntu, it’s changed; use “udevadm monitor” now:

$ udevadm help
Usage: udevadm COMMAND [OPTIONS]
info query sysfs or the udev database
trigger request events from the kernel
settle wait for the event queue to finish
control control the udev daemon
monitor listen to kernel and udev events
test simulation run
version print the version number
help print this help text

It looks like udevmonitor was a symlink, and around April 2008, that symlink was removed. Someone asked about it on the Linux kernel mailing list and received this reply:

All udev tools are in one single binary called “udevadm”, which is
always in /sbin, and not like the old tools spread around in /sbin,
/usr/bin, /usr/sbin. See “man udev” for the reference to udevadm, and
“man udevadm” for the commands, which have been the individual tools
before.

So if you have a USB device that causes a hard freeze of your Linux computer when you plug it in, and you want to run udevmonitor to debug it, use udevadm monitor instead.