And just in case, for Debian and related distributions, the release information is stored into

And FWIW in CRUX I can use the crux command, which in turn is a script which just echoes the wanted info, hardcoded there. The lesson to be learnt here is that not only the question has nothing to do with Perl, but also that it is one that hardly has an answer, since it's up to each distro to provide that info, and each distro provides it, or possibly doesn't, in its own way, i.e. there appears not to be a standard.

However as fenLisesi++ points out, some more info seems to be available in /proc/version, specifically in the C compiler description: I've now checked 6 systems which comprise 4 different distros, namely CRUX, Mandriva, Debian and Gentoo; but I don't have the slightest idea how all this may be in general - and there are far many more distros out there...