Thank you MK27 You are right, but I thought that at least "lsb_release" will work!!!

This program works in my office, but now I'm going to search more and read some services code to detect the way!!!!

But I have to say this too:
most of programs and distributions are in .deb, .rpm and tar.gz files. I think with these extensions the distribution is chosen by the user itself?!

Thanks again & again