How does one recover deleted device nodes without rebooting?

I had a shell script that had an undefined variable.

The script command that failed was

The variable $SOME_VARIABLE was undefined because of a typo. The infamous typo.

The script is fixed, but from an admin perspective the discovery has me wondering how to resolve a bigger problem.

Some device nodes were deleted when the script executed the broken command. In particular that caused me to hunt this down was the loss of /dev/dvb, which resulted in the system not being able to record.

I am not a udev guru at all. I have tinkered some to no avail with udevadm trying to recover the lost device nodes. I also tried booting to run level 1 and returning. That helps some but I notice a few other quirks. The only reliable method I have discovered is rebooting.

I do not believe mknod helps because that creates a static node.

I surfed the web with no success. Most people seem to recommend rebooting.

I would appreciate some ideas about recovering deleted device nodes.

Thanks.

What "tinkering" ?. Did you try a trigger with the appropriate subsystem (probably dvb) ?.

Reloading the DVB kernel module concerned (eg dvb-core) should be all that's required.

I tried the trigger command. Do you have a more specific command in mind?

Deleting the /dev/dvb node does not affect module status. I checked before posting. The lsmod output remains the same after /dev/dvb is deleted.

That's because you've got it the wrong way round. Reload the kernel driver and the device node should be recreated.

I tried the following.

Simulate the original script error with the undefined variable:
umount -f -l /dev/

rmmod cx2341x
rmmod cx18_alsa
rmmod cx18
rmmod dvb_core

modprobe dvb_core
modprobe cx18
modprobe cx2341x

At that point /dev/dvb still does not exist.

udevadmin trigger perhaps?

The device concerned may need reinitialising. Is it a USB-attached device? If so, physically reconnecting it should do the trick. Alternatively, udevadm trigger (as has already been suggested) with something like
where xxxx pertains to the vendor ID of the device concerned.

No luck thus far. I tried the following:

Where 14f1 is the vendor id of the TV capture card, harvested from the lspci command.

1) I don't have a definitive answer here, but you might want to check that "idVendor" is a valid attribute for that device.

https://wiki.archlinux.org/index.php...es_of_a_device

2) I'm in uncharted territory with this, but perhaps it is feasible to reset the device (to cause it to be re-initialised without rebooting the OS) as described here:
http://unix.stackexchange.com/questi...-a-pcie-device

Other than that, I'm not sure what else to suggest. Good luck.