while experimenting with various sound definitions and trying to solve a few problems I realized a file named dsp, which had somehow disappeared, was missing and that this was the cause of my inability to make the audio work.

However, I did not know how to get it back there. The cumbersome solution I finally found was to run the entire installation of my Mandrake 8.1 anew in update mode, so it just fixed things without changing anything else.

But I am almost sure there must be a more legant way to correct such problems. Any idea how?

Thanks.

man rpm

Pay special attention to the query options. If you know the name of a file and want to know what package it came from, do this:

rpm -q -f <name of file>

This will display the name of the file that originally installed the file. Then you can use rpm to re-install the package. Look at man rpm again and look at the update (-U or -F) options. When you do the full Mandrake update, it does this for all packages that are installed, which is sort of a waste of time, but it does work.

"dsp" is a device under /dev, there's a script in /dev called smptin like "MAKEDEV" that can do the dirty work using "mknod" itself. If you want to DIY you'll need the major and minor number from MAKEDEV and read man mknod first.
It should look smptin like "mknod -m 666 /dev/dsp c 14 3".