On 25 May 2015 at 19:44, Jens Staal <staal1978@gmail.com> wrote:

> It did however not work (I guess the "..." and "##" are to blame?) so now
> I wonder how/if it is possible with the posix compiler on plan9?


It doesn't understand the named ... variant, which I suppose is more recent
tinkering. Use the older __VA_ARGS__.
Also I didn't think your use of ## was correct in any case (you can only
concatenate things that produce a valid token).

It looked as though

#define err(exitcode, format, ...) \
  errx(exitcode, format ": %s", __VA_ARGS__, strerror(errno))

etc might work.