Re: Newbie question - testing for OS. . .

[Ken Smith]

On 12/19/06, Mike Shal <address@hidden> wrote:
> On 12/19/06, Dave Korn <address@hidden> wrote:
> > On 19 December 2006 22:08, bC wrote:
> >
> > >   I've built a couple simplistic make files to install my program, needed
> > > data files and libraries.... one aimed at being used on Fedora Core 3, the
> > > other on Fedora Core 5.  Those are currently the two favorites of my target
> > > audience; and I've found them to vary in what libraries are present by
> > > default.
> > >
> > >   I'd like to maintain just the one make file... so, I need a test and
> > > decision based upon which version of the OS the make utility finds itself
> > > running under.  I would appreciate a kick-start in the right direction.
> >
> >   Perhaps something along the lines of
> >
> > OS_VERSION=$(shell uname)
> >
>
> Though keep in mind that everytime you use $(OS_VERSION) it will
> execute another shell command. If you use $(OS_VERSION) in more than
> one place, you probably want:
>
> OS_VERSION:=$(shell uname)
>
> (note the ":=") This will execute the shell only once, when the
> variable is declared.

All good points.  I have only to add that uname without arguments will
give you useful platform information but it may lack any sort of
pertinent version information.  I find the following to be fairly
portable and a pretty good way to dial makefile settings to a
particular platform.

osname := $(shell uname -s)
osver := $(shell uname -r)
cpuarch := $(shell uname -m)

Then you can do things like this, for example.

Darwin-8.8.1-i386-CFLAGS := -DMACOSX_X86
SunOS-5.9-sun4u-CFLAGS := -DSOL9_SPARC

CFLAGS := $($(osname)-$(osver)-$(cpuarch)-CFLAGS)

 HTH,
 Ken Smith