Linux/Mac: What is good method to determine platform at compile time?

Question

I would like to generalize a build system to compile on several (somewhat similar) platforms. What is a good method for determining the type of host that the shell script or Makefile is running on. I would like to distinguish between mac and linux, but also different specific distributions of linux (e.g. RHEL, Ubuntu). Cygwin is not important for me, but if you include it in your response I am sure others will find it valuable.

The rationale may include using the host type to fetch and install the correct versions of binary packages when it is more convenient to do so than compile from source. In addition, some commercial software is binary-packaged for specific distros, so part of the motivation is to grab the right binary.

Thanks,

SetJmp

Answer 1

uname -a to distinguish major *nix variants

Not so sure what the best way to distinguish red hat from ubuntu would be - could look for package managing tools and query installed packages, eventually helping you narrow down different debian derivatives, etc. There's probably something more obvious and up front though.

Answer 2

linux variants generally store distro information in /etc/issue.

most kernels will put info in /proc/version

Answer 3

Autotools to the rescue. It has tons of macros that help you do this kind of stuff.

http://www.lrde.epita.fr/~adl/autotools.html

Answer 4

It's not completely straightforward. You can use uname to find out the general parameters but to differentiate between distributions is a harder task. Maybe you should consider using something like autoconf to generalise your build system?

Answer 5

Just in case you're using Qt, there's this really nice set of defines, Q_OS_*, that guide you to the Operating System you're compiling on:

Q_OS_AIX
Q_OS_BSD4
Q_OS_BSDI
Q_OS_CYGWIN
Q_OS_DARWIN
Q_OS_DGUX
Q_OS_DYNIX
Q_OS_FREEBSD
Q_OS_HPUX
Q_OS_HURD
Q_OS_IRIX
Q_OS_LINUX
Q_OS_LYNX
Q_OS_MAC
Q_OS_MSDOS
Q_OS_NETBSD
Q_OS_OS2
Q_OS_OPENBSD
Q_OS_OS2EMX
Q_OS_OSF
...

They are defined in QtGlobal. There are even defines that help you figure out the compiler used Q_CC_* or the target Windowing System Q_WS_*.

But if you're not using Qt and want to go for a generic method, you most likely have to fall back to the Autotools package or CMake.

Determining Linux distributions is pretty tricky, but not hard. You first have to figure out what distributions you care about and then make all kinds of distribution specific file/configuration checks like in this example for the ones you've chosen, since you can't really support all of the myriad of Linux distros available out the. :-)

As for the Mac side i'll let the Mac experts answer, but it shouldn't be that hard, since at least the diversity issue is out of the question.