Re: true,false: --version,--help exit code

[Jim Meyering]

On Tue, Jun 3, 2014 at 5:16 AM, Pádraig Brady <address@hidden> wrote:
> On 06/03/2014 01:12 PM, Eric Blake wrote:
...
>> Oh, good point.  Maybe it's better to consistently have --help/--version
>> return status 0 (we successfully printed output) or 1 (we encountered
>> write failure) regardless of the program being executed (which means
>> true is doing it right, and 'false --version' is the odd man out,
>> opposite to what the most recent patch proposal does).  I'd wait for
>> Paul and/or Jim to weigh in on this, since they made the decisions
>> behind the current unpatched behavior.
>
> My slight preference is to change true to be consistent,
> as then it's consistent on all implementations, not
> just within coreutils. I.E. the following would now hold everywhere:
>
>   true --help > /dev/full && echo always ok

My rationale in making true --help > /dev/full diagnose the error was
to consistently enable detection of write failure.  With --help and
--version, we are outside the bounds of POSIX spec. The amended
spec is that the program must print the requested output and exit
with status reflecting success or failure of the write. Without that
check, someone attempting to write-then-parse that help output
would be unable to distinguish the successful case and one in which
the write hit e.g., EIO or ENOSPC.

IMHO, there is no reason to ignore such a write error.
Hence, false --version and false --help (currently always failing) are the
ones I would change, so that they succeed when there is no write error.