Re: tail question

[Bob Proulx]

Paul Eggert wrote:
> The only thing that's changed recently is the choice of the default
> behavior if neither the installer nor the user specifies a preference.
> In this case, coreutils looks at <unistd.h>'s _POSIX2_VERSION to
> determine the system default.  Some implementations have recently
> claimed (typically incorrectly, I guess) to conform to the POSIX
> 1003.1-2001 standard for utilities and have therefore set <unistd.h>'s
> _POSIX2_VERSION to 200112L.  The coreutils build process by default
> takes them at their word.
> 
> I typically use the latest Debian stable distribution (3.0r1).
> It doesn't have this problem since its <unistd.h> says that
> _POSIX2_VERSION is 199209L, which corresponds to POSIX 1003.2-1992.
> But I gather that other, more bleeding-edge distributions claim
> conformance to the newer POSIX standard.

And Debian unstable now claims 200112L in <unistd.h>.  But the Debian
maintainer of coreutils has modified it so that coreutils is still
conforming to the old standard and not yet the new one by default.
This is a good thing and giving them some breathing room.  Setting
_POSIX2_VERSION=200112 in the environment allows people to test
conformance to the newer standard and fix whatever needs to be fixed
without it being a panic to do so.

Bob