Possible values from sys.platform?

┍━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━┑│ System              │ Value               │┝━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━┥│ Linux               │ linux or linux2 (*) ││ Windows             │ win32               ││ Windows/Cygwin      │ cygwin              ││ Windows/MSYS2       │ msys                ││ Mac OS X            │ darwin              ││ OS/2                │ os2                 ││ OS/2 EMX            │ os2emx              ││ RiscOS              │ riscos              ││ AtheOS              │ atheos              ││ FreeBSD 7           │ freebsd7            ││ FreeBSD 8           │ freebsd8            ││ FreeBSD N           │ freebsdN            ││ OpenBSD 6           │ openbsd6            │┕━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━┙

(*) Prior to Python 3.3, the value for any Linux version is always linux2; after, it is linux.

Mac OS X (10.4, 10.5, 10.7, 10.8):

darwin

Linux (2.6 kernel):

linux2

Windows XP 32 bit:

win32

Versions in brackets have been checked - other/newer versions are likely to be the same.

As others have indicated, sys.platform is derived from the name that the system vendor gives their system. However, Python also adds plat- to sys.path, so you can look at all the plat-* directories in the Python distribution.

This gives you the list

aix3 aix4 atheos beos5 darwin freebsd2 freebsd3 freebsd4 freebsd5 freebsd6 freebsd7 generic irix5 irix6 linux2 mac netbsd1 next3 os2emx riscos sunos5 unixware7

Of course, sys.platform can have additional values, when Python gets compiled on a system for which no platform-specific directory has been created.

From here.