$ ./cppsym
_AIX
_AIX32
_AIX41
_AIX43
_ALL_SOURCE
_ANSI_C_SOURCE
_BIG_ENDIAN
__BIG_ENDIAN__
_IBMR2
_LARGE_FILE_API
_LONG_LONG
_LP64
__LP64__
_POSIX_C_SOURCE
_POSIX_SOURCE
_POWER
_XOPEN_SOURCE
_XOPEN_SOURCE_EXTENDED
__unix
__unix__