How to run .rpm files on different flavors of linux?
i.e. Ubuntu mandrak suse

alien

You could use alien as said to convert between package formats. But I'd try to find a package that works for your distro first. And, if not possible, try to find a tarball or zip file with the sources and compile it yourself.

I've only ever used rpm2tgz way back on Slack 9. Suppose that's something.

Installing a package not intended for your distribution and version will very often mess up your system because it doesn't rely on the same components, for instance libraries.

If you can't find a package for an application you need, my advice is to make yourself one so at least it will be easy to remove.

I have always compiled from source if i cannot find a package, even then, the package may not always have the feature(s) I want enabled in the package, so I would have to recompile from source anyway.
But Slackware is rpm2tgz, and very often the rpm packages do not work on Slack...
Not sure about Ubuntu, Mandrake, and Suse.

Mandrake and Suse work with rpm as far as I know...

Suse installs them with yast, I don't remember how Mandrake used to do it (I was still a newbie when I used it)

As for Ubuntu... it already has more packages then any other distro... If you actually do find something that isn't in it's repository, compiling from source is the safest option. Otherwise, use alien, as the others have said

Sometimes the converting procedure doesn't work, because all distros are different each other. In particular the "not-derived" distros. So, it's very hard to convert a .rpm package built for mandriva(and derives...) on slackware, they use different directories where save programs, etc...So, maybe files could be saved in different places and something couldn't work correctly. Bye.

ubuntu has lots and lots of software. You should not need to convert from any other distro.

If that was true there wouldn't be ubuntu users trying to learn how to compile from source or install binary packages. "A lot" != "everything".

Being that said, if the package doesn't exist, I agree that it's always better to create one, so the install/uninstall process is clean. If you can't for any reason, better compile from source and leave the source tree so you can do make uninstall.

I've never used alien and only rarely I use rpm2targz to be able to pick some binaries from a file, but when I do so I store them in my home and just tweak the LD_LIBRARY_PATH and be done with that. I don't like to go dropping .so files around that my package manager is not aware of, because they will cause problems and conflicts for sure in the future.