Hi all, Currently the unix package is a mishmash of different solutions to the portability problem. Here are all the ones I've found, along with what I think the best action would be. If this sounds reasonable then I'll start making patches and proposals as appropriate. (for POSIX/SUS, see http://www.opengroup.org/onlinepubs/009695399/) 1) Values outside of the scope of the package, conditionally available: * System.Posix.Signals.Exts.* Propose: Moving modules into a new package, unix-exts perhaps. 2) Things that fall back to probably-reasonable alternatives: * unsetEnv, setEnv * PATH_MAX Propose: Leave as they are. 3) Things falling back to functionality which can cause problems: * The Haskell usleep uses the C usleep (marked Obsolescent) if nanosleep (a Timer extension) isn't available. C's usleep interacts badly with GHC's threaded RTS. Propose: Leave as it is. 4) Things that raise errors at runtime if they are not available, but there is something we could fall back to: * getGroupEntryForID (getgrgid_r, thread-safe extension) * getGroupEntryForName (getgrnam_r, thread-safe extension) Propose: Write fallback code. 5) Things that raise errors at runtime if they are not available, but as far as I can see are required to be available anyway: * _PC_* in System/Posix/Files.hsc * getUserEntryForID (getpwuid) * getUserEntryForName (getpwnam) * grBufSize (sysconf, _SC_GETGR_R_SIZE_MAX) * pwBufSize (sysconf, _SC_GETPW_R_SIZE_MAX) * sysconfWithDefault (sysconf) Propose: Change to using them unconditionally and see if any platforms break. 6) Things depending on optional functionality, conditionally available: * setSymbolicLinkOwnerAndGroup depends on lchown, an XSI extension http://www.opengroup.org/onlinepubs/009695399/functions/lchown.html * RLIMIT_AS (ResourceTotalMemory), RLIM_SAVED_MAX, RLIM_SAVED_CUR (all of the rlimit stuff actually appears to be an XSI extension). Propose: Move to unix-xsi package. 7) Things that raise errors at runtime if they are not available: * getAllGroupEntries (getgrent, XSI extension) * getAllUserEntries (getpwent, setpwent, endpwent, XSI extensions) * Various in DynamicLinker.Prim Propose: Move to unix-xsi package. (for both 6 and 7, an alternative would be to just make them unconditionally used in the unix package; I'm not sure what platforms, if any, this would break on). 8) Things that are implemented only for certain compilers: * forkProcess (GHC-only) Propose: Write implementations for other compilers/interpreters. Thanks Ian