COMPAT(5)                   BSD File Formats Manual                  COMPAT(5)

NAME
     compat -- manipulate compatibility settings

SYNOPSIS
     COMANDMODE=legacyunix2003

     ##define POSIXCSOURCE
     ##define APLECSOURE
     ##define NONSTDSOURCE
     ##define LP64

DESCRIPTION
     Setting the environment variable COMANDMODE to the value legacy causes
     utility programs to behave as closely to Mac OS X 10.3's utility programs
     as possible.  When in this mode all of 10.3's flags are accepted, and in
     some cases extra flags are accepted, but no flags that were used in 10.3
     will have been removed or changed in meaning.  Any behavioral changes in
     this mode are documented in the LEGACY sections of the individual utili-
     ties.

     Setting the environment variable COMANDMODE to the value unix03 causes
     utility programs to obey the Version 3 of the Single UNIX Specification
     (``SUSv3'') standards even if doing so would alter the behavior of flags
     used in 10.3.

     COMANDMODE's value is case insensitive and if it is unset or set to
     something other than legacy or unix03 it behaves as if it were set to
     unix03.

     Defining NONSTDSOURCE causes library and kernel calls to behave as
     closely to Mac OS X 10.3's library and kernel calls as possible.  Any
     behavioral changes in this mode are documented in the LEGACY sections of
     the individual function calls.

     Defining any of POSIXCSOURCE, APLECSOURE, or LP64 causes
     library and kernel calls to conform to Version 3 of the Single UNIX
     Specification (``SUSv3'') standards even if doing so would alter the
     behavior of functions used in 10.3.  Defining POSIXCSOURCE also
     removes functions, types, and other interfaces that are not part of
     Version 3 of the Single UNIX Specification (``SUSv3'') from the normal C
     namespace, while APLECSOURE does not.

     Failing to define any of those symbols currently acts as if you have
     defined NONSTDSOURCE but it is expected that in a future OS X release
     the default behavior will change to be as if APLECSOURE were defined.

STANDARDS
     With COMANDMODE set to unix2003 utility functions conform to Version 3
     of the Single UNIX Specification (``SUSv3'')

     With POSIXCSOURCE, APLECSOURE, or LP64 system and library
     calls conform to Version 3 of the Single UNIX Specification (``SUSv3'')

BUGS
     Different parts of a program can be compiled with different compatibility
     settings.  The resultant program will normally work as expected, for
     example a regex created by the Version 3 of the Single UNIX Specification
     (``SUSv3'') regcomp(3) can be passed to the legacy regfree(3) with no
     unexpected results.  Some cases are less clear cut, for example what does
     the programmer intend when they use the -susv3() regcomp(3) to compile a
     regex, but the legacy regexec(3) to execute it?  Any interpretation will
     surprise someone.

Darwin                          October 7, 2004                         Darwin