Re: diffutils 2.8 and -u/-U options

[Paul Eggert]

Ignacio Goyret <address@hidden> writes:

> May I ask what was the rationale behind disallowing -NUM altogether?
> I understand the desire to follow POSIX whims,

That was it, yes.  We've recently gotten a further interpretation from
the POSIX folks that will let us bring back -NUM as an extension to
POSIX, but the system integration work isn't done yet.  However,
please note that portable scripts will still not be able to use -NUM,
since POSIX does not require it.

> this move broke a bunch of tools that do not know anything about the
> new -U and -C options (eg, rcsdiff, cvs diff, etc).

rcsdiff and cvs diff both work with -C as far as I know.  And cvs diff
works with -U.  So the problem is limited to rcsdiff -U.  As a
workaround in the mean time, you can use --unified=NUM instead.  (This
works with both rcsdiff and cvs diff.)

> Is there an environment variable that one can set to make diff ignore
> these POSIX silliness

Yes.  _POSIX2_VERSION.  Please see the documentation.