OperatingSystems.md

July 5, 2025 · View on GitHub

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AIX

Type	Macro	Description
Identification	`_AIX`
Version	`_AIX'VR'`	V = Version R = Revision
Identification	`__TOS_AIX__`	Defined by xlC

If _AIX is defined, then the following macros can be used to determine the version. Notice that the macros indicates the mentioned version or higher. For example, if _AIX43 is defined, then _AIX41 will also be defined.

AIX Version	Macro
3.2.x	`_AIX3` `_AIX32`
4.1	`_AIX41`
4.3	`_AIX43`

Android

Type	Macro	Format	Description
Identification	`__ANDROID__`
Version	`__ANDROID_API__`	V	V = API Version Must be included from `<android/api-level.h>`

Notice that Android uses Linux kernel, and that the Linux macros also are defined for Android.

Example

Android Version	`__ANDROID_API__`
1.0	1
1.1	2
1.5	3
1.6	4
2.0	5
2.0.1	6
2.1	7
2.2	8
2.3	9
2.3.3	10
3.0	11

Amdahl UTS

Type	Macro
Identification	`UTS`

AmigaOS

Type	Macro	Description
Identification	`AMIGA`
Identification	`__amigaos__`	Defined by GNU C

Apollo AEGIS

Type	Macro
Identification	`aegis`

Apollo Domain/OS

Type	Macro
Identification	`apollo`

AROS

Originally Amiga Research Operating System, later renamed to AROS Research Operating System.

Type	Macro
Identification	`__AROS__`

Bada

Based on Nucleus OS.

BeOS

Type	Macro	Format	Description
Identification	`__BEOS__`
Version	`B_BEOS_VERSION`	0xVVRR	VV = Version RR = Revision Must be included from `<BeBuild.h>`

Blue Gene

Type	Macro	Description
Identification	`__bg__`	All Blue Gene systems Defined by XL C/C++ and GNU C
Version	`__bgq__`	Blue Gene/Q Defined for XL C/C++ and GNU C
Identification	`__THW_BLUEGENE__`	All Blue Gene systems Defined by XL C/C++
Version	`__TOS_BGQ__`	Blue Gene/Q Defined by XL C/C++

BSD Environment

Type	Macro	Format	Description
Identification	`__FreeBSD__` `__NetBSD__` `__OpenBSD__` `__bsdi__` `__DragonFly__` `__MidnightBSD__`
Version	`BSD`	YYYYMM	YYYY = Year MM = Month Must be included from `<sys/param.h>`
Version	`BSD4_2` `BSD4_3` `BSD4_4`		Must be included from `<sys/param.h>`
Identification	`_SYSTYPE_BSD`		Defined by DEC C

Example

Version	`BSD`	Macro
4.3 Net2	199103
4.4	199306	`BSD4_4`
4.4BSD-Lite2	199506

BSD/OS

Type	Macro
Identification	`__bsdi__`

ConvexOS

Type	Macro
Identification	`__convex__`

CP/M

Type	Macro	Format	Description
Identification	`__CPM`		Defined by Z88DK
Identification	`CPM`		Defined by Z88DK

Cygwin Environment

Type	Macro
Identification	`__CYGWIN__`

DG/UX

Type	Macro
Identification	`DGUX`
Identification	`__DGUX__`
Identification	`__dgux__`

DragonFly

Type	Macro
Identification	`__DragonFly__`

DYNIX/ptx

Type	Macro
Identification	`_SEQUENT_`
Identification	`sequent`

eCos

Type	Macro
Identification	`__ECOS`

Emscripten

Type	Macro	Format	Description
Identification	`EMSCRIPTEN`		From Emscripten 1.0.1a until Emscripten 1.30.6
Identification	`__EMSCRIPTEN__`		From Emscripten 1.3.7
Version	`__EMSCRIPTEN_major__`	V	V = Major version From Emscripten 1.21.4 Must be included from `<emscripten/version.h>`
Version	`__EMSCRIPTEN_minor__`	R	R = Minor version From Emscripten 1.21.4 Must be included from `<emscripten/version.h>`
Version	`__EMSCRIPTEN_tiny__`	P	P = Patch level From Emscripten 1.21.4 Must be included from `<emscripten/version.h>`

For more information see Detecting Emscripten in Preprocessor

Example

Version	`__EMSCRIPTEN_major__`	`__EMSCRIPTEN_minor__`	`__EMSCRIPTEN_tiny__`
3.1.41	3	1	41
3.1.41-git	3	1	41

EMX Environment

Type	Macro
Identification	`__EMX__`

FreeBSD

Type	Macro	Format	Description
Identification	`__FreeBSD__`
Identification	`__FreeBSD_kernel__`		From FreeBSD 8.3, 9.1, and 10.0.1
Version	`BSD`
Version	`__FreeBSD__`	V	V = Version
Version	`__FreeBSD_version`	?	Must be included from `<sys/param.h>`

Example

FreeBSD	`__FreeBSD__`	`__FreeBSD_version`
1.x	1
2.0-RELEASE	2	119411
2.2-RELEASE	2	220000
3.0-RELEASE	3	300005
4.0-RELEASE	4	400017
4.5-RELEASE	4	450000

For more information see the FreeBSD porters handbook.

Fuchsia

Type	Macro	Format	Description
Identification	`__Fuchsia__`		1
Version	`__Fuchsia_API_level__`	V	V = API level 1

GNU aka GNU/Hurd

The official name of this operating system is GNU. Hurd is the kernel in the GNU operating system. It is often listed as GNU/Hurd since there is also GNU/Linux and GNU/kFreeBSD, which are most of the GNU operating system with the Linux and FreeBSD kernels respectively.

Type	Macro
Identification	`__GNU__` 1
Identification	`__gnu_hurd__` 1

GNU/kFreeBSD

GNU/kFreeBSD is one of the Debian distros that is based on the FreeBSD kernel rather than the Linux or Hurd kernels.

Type	Macro
Identification	`__FreeBSD_kernel__` `&&` `__GLIBC__`

Notice that FreeBSD also defines __FreeBSD_kernel__ so the __GLIBC__ macro must be checked to distinguish it.

GNU/Linux

Type	Macro
Identification	`__gnu_linux__`

Haiku

Type	Macro	Format	Description
Identification	`__HAIKU__`
Version	`B_HAIKU_VERSION_'V'`	0x00VV0000	VV = Version Defined in advance before being reached. Must be included from `<BeBuild.h>`
Version	`B_HAIKU_VERSION`	0x00VVRRPP	VV = Version RR = Revision (Alpha and Beta ordering for VV+1) PP = Pre (0 or 1 if before RR+1) Must be included from `<BeBuild.h>`

Example

Haiku	`B_HAIKU_VERSION`
1 Alpha 1	`B_HAIKU_VERSION_1_ALPHA_1` = 0x00000100
1 Alpha 4	`B_HAIKU_VERSION_1_ALPHA_4` = 0x00000400
1 Beta 1	`B_HAIKU_VERSION_1_BETA_1` = 0x00000500
Git version before 1 Beta 4	`B_HAIKU_VERSION_1_PRE_BETA_4` = 0x00000701
1	`B_HAIKU_VERSION_1` = 0x00010000

HI-UX MPP

Type	Macro
Identification	`__hiuxmpp`

HP-UX

Type	Macro	Description
Identification	`_hpux`	Defined by HP UPC
Identification	`hpux`
Identification	`__hpux`

IBM OS/400

Type	Macro	Format	Description
Identification	`__OS400__`
Version	`__OS400_TGTVRM__`	VRM	V = Version R = Revision M = Modification

illumos

Type	Macro	Description
Identification	`__illumos__`	See also: 13726 distinguish ourselves with a macro
Identification	`sun`	Shared with Solaris; use not recommended
Identification	`__sun`	Shared with Solaris; use not recommended

Note that illumos forked from Solaris in ~2010, but continues to provide the identifying definitions that Solaris provided at the point of the fork.

INTEGRITY

Type	Macro
Identification	`__INTEGRITY`

Interix Environment

Type	Macro	Description
Identification	`__INTERIX`	Defined by GNU C and Visual C++

IRIX

Type	Macro
Identification	`sgi`
Identification	`__sgi`

Linux kernel

Systems based on the Linux kernel define these macros. There are two major Linux-based operating systems: GNU/Linux and Android, and numerous others like Ångström or OpenEmbedded

Type	Macro	Description
Identification	`__linux__`	1
Identification	`linux`	Obsolete (not POSIX compliant)
Identification	`__linux`	Obsolete (not POSIX compliant)

LynxOS

Type	Macro
Identification	`__Lynx__`

MacOS

Type	Macro	Description
Identification	`macintosh`	Mac OS 9
Identification	`Macintosh`	Mac OS 9
Identification	`__APPLE__` `&&` `__MACH__`	Mac OS X Defined by GNU C and Intel C++

Microware OS-9

Type	Macro	Description
Identification	`__OS9000`	Defined by Ultimate C/C++
Identification	`_OSK`	Defined by Ultimate C/C++

MidnightBSD

Type	Macro	Description
Identification	`__MidnightBSD__`
Identification	`__MidnightBSD_kernel__`
Version	`BSD`
Version	`__MidnightBSD_version`	Must be included from `<sys/param.h>`

MINIX

Type	Macro
Identification	`__minix`

MiNT

Originally MiNT is Not TOS, later renamed to MiNT is Now TOS.

Type	Macro
Identification	`__MINT__`

MorphOS

Type	Macro
Identification	`__MORPHOS__`

MPE/iX

Type	Macro
Identification	`mpeix`
Identification	`__mpexl`

MSDOS

Type	Macro
Identification	`MSDOS`
Identification	`__MSDOS__`
Identification	`_MSDOS`
Identification	`__DOS__`

MSX

Type	Macro	Format	Description
Identification	`__MSX`		Defined by Z88DK
Identification	`MSX`		Defined by Z88DK

Native Client

Type	Macro
Identification	`__native_client__`

NetBSD

Type	Macro	Format	Description
Identification	`__NetBSD__`
Version	`BSD`
Version	`NetBSD'V'_'R'`		V = Version R = Revision Must be included from `<sys/param.h>`
Version	`__NetBSD_Version__`	VVRRAAPP00	VV = Version RR = Revision AA = Release PP = Patch From NetBSD 1.2D (?) until NetBSD 2.0H Must be included from `<sys/param.h>`
Version	`__NetBSD_Version__`	VVRR00PP00	VV = Version RR = Revision PP = Patch From NetBSD 2.99.9 Must be included from `<sys/param.h>`

Example

NetBSD	`__NetBSD_Version__`	Macro
0.8		`NetBSD0_8`
0.9		`NetBSD0_9`
1.0		`NetBSD1_0` = 1
1.0A		`NetBSD1_0` = 2
1.2D	102040000
1.2.1	102000100

NeXTSTEP

Type	Macro
Identification	`NeXT`

NonStop

Type	Macro
Identification	`__TANDEM`

Nucleus RTOS

Type	Macro
Identification	`__nucleus__`

OpenBSD

Type	Macro	Description
Identification	`__OpenBSD__`
Version	`BSD`
Version	`OpenBSD'V'_'R'`	V = Version R = Revision Must be included from `<sys/param.h>`

Example

OpenBSD	Macro
3.1	`OpenBSD3_1`
3.9	`OpenBSD3_9`

OS/2

Type	Macro
Identification	`OS2`
Identification	`_OS2`
Identification	`__OS2__`
Identification	`__TOS_OS2__`

Palm OS

Type	Macro	Description
Identification	`__palmos__`	Defined by GNU C in PRC-Tools

Plan 9

Type	Macro
Identification	`EPLAN9`

Pyramid DC/OSx

Type	Macro
Identification	`pyr`

QNX

Type	Macro	Format	Description
Identification	`__QNX__`		QNX 4.x, 7.x, 8.x
Identification	`__QNXNTO__`		QNX 6.x
Version	`_NTO_VERSION`	VRR	V = Version RR = Revision Only available when `__QNXNTO__` is defined. Must be included from `<sys/neutrino.h>`
Version	`BBNDK_VERSION_CURRENT`	VVRRRRPPPP	V = Version RRRR = Revision PPPP = Patch Only available on Blackberry 10 From Blackberry 10.1.0 Must be included from `<bbndk.h>`

Example

QNX	`_NTO_VERSION`
6.2	620

Reliant UNIX

Type	Macro
Identification	`sinux`

SCO OpenServer

Type	Macro	Description
Identification	`M_I386`	Defined by GNU C
Identification	`M_XENIX`	Defined by GNU C
Identification	`_SCO_DS`

SerenityOS

Type	Macro	Description
Identification	`__serenity__`	Defined by GNU C and Clang

Solaris

Type	Macro	Description
Identification	`sun`
Identification	`__sun`
Version	`__'System'_'Version'`	System = `uname -s` Version = `uname -r` Any illegal character is replaced by an underscore. Defined by Sun Studio

Use the SVR4 macros to distinguish between Solaris and SunOS.

#if defined(sun) || defined(__sun)
# if defined(__SVR4) || defined(__svr4__)
/* Solaris */
# else
/* SunOS */
# endif
#endif

Example

Solaris	Macro
2.7	`__SunOS_5_7`
8	`__SunOS_5_8`

Stratus VOS

Type	Macro	Format	Description
Identification	`__VOS__`
Version	`__VOS__`	V	V = Version

Notice that the __VOS__ macro is defined by the compiler, but as several compilers can co-exist in the same OS release, the version number is not reliable.

SVR4 Environment

Type	Macro	Description
Identification	`__sysv__`
Identification	`__SVR4`
Identification	`__svr4__`
Identification	`_SYSTYPE_SVR4`	Defined on IRIX

Syllable

Type	Macro
Identification	`__SYLLABLE__`

Symbian OS

Type	Macro
Identification	`__SYMBIAN32__`

Tru64 (OSF/1)

Type	Macro
Identification	`__osf__`
Identification	`__osf`

Ultrix

Type	Macro
Identification	`ultrix`
Identification	`__ultrix`
Identification	`__ultrix__`
Identification	`unix` & `vax`

UNICOS

Type	Macro	Format	Description
Identification	`_UNICOS`
Version	`_UNICOS`	V	V = Version

UNICOS/mp

Type	Macro	Description
Identification	`_CRAY` `__crayx1`

UNIX Environment

Type	Macro
Identification	`__unix__`
Identification	`__unix`

Notice that not all compilers defines these macros, e.g. the xlC or the DEC C/C++ compiler, so it may be better to use the POSIX or X/Open standard macros instead.

UnixWare

Type	Macro
Identification	`sco`
Identification	`_UNIXWARE7`

U/Win Environment

Type	Macro
Identification	`_UWIN`

VMS

Type	Macro	Format	Description
Identification	`VMS`
Identification	`__VMS`
Version	`__VMS_VER`	VVRREPPTT	VV = Version RR = Revision E = Edit number PP = Patch (01 = A, ... 26 = Z) TT = Type (22 = official)

Example

VMS	`__VMS_VER`
6.1	60100022
6.2	60200022
6.2-1I	60210922

VxWorks

Type	Macro	Description
Identification	`__VXWORKS__`	Defined by GNU C and Diab (from ?)
Identification	`__vxworks`	Defined by GNU C and Diab (from ?)
Version	`_WRS_VXWORKS_MAJOR`	Version Must be included from `<version.h>`
Version	`_WRS_VXWORKS_MINOR`	Revision Must be included from `<version.h>`
Version	`_WRS_VXWORKS_MAINT`	Patch/maintenance Must be included from `<version.h>`
Mode	`__RTP__`	For real-time mode
Mode	`_WRS_KERNEL`	For kernel mode

Example

VxWorks	`_WRS_VXWORKS_MAJOR`	`_WRS_VXWORKS_MINOR`	`_WRS_VXWORKS_MAINT`
6.2	6	2	0

Windows

Type	Macro	Description
Identification	`_WIN16`	Defined for 16-bit environments 1
Identification	`_WIN32`	Defined for both 32-bit and 64-bit environments 1
Identification	`_WIN64`	Defined for 64-bit environments 1
Identification	`__WIN32__`	Defined by Borland C++
Identification	`__TOS_WIN__`	Defined by xlC
Identification	`__WINDOWS__`	Defined for 16-bit-environments by Watcom C/C++ 1

Windows CE

Type	Macro	Format	Description
Identification	`_WIN32_WCE`		Defined by Embedded Visual C++
Version	`_WIN32_WCE`	VRR	V = Version R = Revision
Identification	`WIN32_PLATFORM_'P'`		P = Platform
Version	`WIN32_PLATFORM_'P'`	V	P = Platform V = Version

Example

Version	`_WIN32_WCE`
2.01	201
2.11	211
3.0	300
4.0	400
4.1	410
4.2	420
5.0	501

Platform	Macro	Value
H/PC 2000	`WIN32_PLATFORM_HPC2000`
H/PC Pro 2.11	`WIN32_PLATFORM_HPCPRO`	211
H/PC Pro 3.0	`WIN32_PLATFORM_HPCPRO`	300
Pocket PC	`WIN32_PLATFORM_PSPC`	1
Pocket PC 2002	`WIN32_PLATFORM_PSPC`	310
Windows Mobile 2003	`WIN32_PLATFORM_PSPC`	400
Smartphone 2002	`WIN32_PLATFORM_WFSP`	100

Wind/U Environment

Type	Macro	Format	Description
Identification	`_WINDU_SOURCE`
Version	`_WINDU_SOURCE`	0xVVRRPP	VV = Version RR = Revision PP = Patch

Example

Wind/U	`_WINDU_SOURCE`
3.1.2	0x030102

MVS/ESA, OS/390 and z/OS

Type	Macro	Description
Identification	`__MVS__`	Host
Identification	`__HOS_MVS__`	Host
Identification	`__TOS_MVS__`	Target

VM/ESA and z/VM

Type	Macro	Description
Identification	`__VM__`	Host
Identification	`__HOS_VM__`	Host
Identification	`__TOS_VM__`	Target