Operating Systems:
-----------------
SunOS .. 4.1:		sun		(abbr.: SunOS4)
Solaris:		sun __svr4__	(abbr.: solaris)
Silicon Graphics:	sgi
AIX:                    _AIX
Atari ST/TT MiNT:	atarist
Amiga, DICE:		AMIGA _DCC
Amiga, SAS/C:		AMIGA __SASC
BeOS                    __BEOS__
FreeBSD:                __FreeBSD__
Linux:			linux
NeXT:			NeXT
Sequent:		_SEQUENT_
Ultrix:			ultrix
IBM RS6000		_AIX _IBMR2
HP-UX			hpux
OS/2			OS2 (not set by all compilers; for some the configure
                             script adds it to the EXTRA_CFLAGS)
???			M_UNIX
Apple Unix		AUX		/* add -D_POSIX_SOURCE to CFLAGS */
Apple Darwin            __APPLE__, __MACH__
Windows NT/95/98        _WIN32, WINNT, _WINNT

Program Loaders:
---------------
msdos:			MSDOS

Processor Hardware:
------------------
Sparc			sparc
x86 (MWerks/Be)         __INTEL__
x86 (gcc)               i386, __i386__
x86 (icc)               _M_IX86
PowerPC (Darwin)        __ppc__
Itanium (ecc)           _M_IA64

compilers:
---------
gcc:			__GNUC__
Apple CC:               __GNUC__, __APPLE_CC__
Cygnus gcc for Win32    __CYGWIN32__ resp. __CYGWIN__
Metrowerks (Be)         __MWERKS__
EMX gcc for OS/2        __EMX__
Intel C/C++ Compiler    __INTEL_COMPILER (expands to version, e.g. 500)

-----------------------------------------------------------------------------

von HP-UX haben wills, hier der Output von gcc -E -dM < /dev/null:

#define __hp9000s800__ 1
#define __unix__ 1
#define __unix 1
#define __hppa 1
#define __hppa__ 1
#define __hpux 1
#define __hpux__ 1
#define __hp9000s700 1
#define __hp9000s700__ 1
#define __hp9000s800 1
#define _ILP32 1
#define __STDC_HOSTED__ 1
#define _PA_RISC1_1 1
#define _HPUX_SOURCE 1

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