Re: POSIX misunderstanding

[Paul Eggert]

Albert Cahalan <address@hidden> writes:

> On Wed, 2004-08-18 at 13:49, Paul Eggert wrote:
>> Albert Cahalan <address@hidden> writes:
>> 
>> > Well, so does the --lines option.
>> 
>> No, that uses an allowed extension.  It's not prohibited, the way that
>> multi-digit options are prohibited.
>
> Where?

Guideline 3 says "Multi-digit options should not be allowed."
That's an explicit prohibition.

> You can have a "-W lines=42" option.

True.

> Guideline 10 seems to require that "head --help"
> be interpreted as "head -- help".

No, it talks only about the argument "--".  "head --help" does not
have an argument "--"; it has an argument "--help".

> the long options violate guideline 3.

I don't see why.  Guideline 3 is about short options.

> The "head" command is described using the word "follows", instead of
> the words "conforms to". (for "head", the standard says "This
> standard version of head follows the Utility Syntax Guidelines."

I don't know where you're getting that wording.  The current edition
of the standard says "The head utility shall conform to the Base
Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility
Syntax Guidelines."  This is a "shall" constraint on implementations
that claim conformance to the standard.  It's pretty straightforward.  See:
<http://www.opengroup.org/onlinepubs/000095399/utilities/head.html>

>> > Guideline 11 isn't even a problem at all, unless you
>> > artificially make it a problem.
>> 
>> Sure it is.  It says that order shouldn't matter unless the options
>> are mutually exclusive and one is documented to override the other.
>> Hence if options like "-1" are and "-3" are allowed, then "-13" must
>> be equivalent to "-1 -3" which in turn should be equivalent to "-3 -1"
>> or "-31".  I suspect that this problem is part of the reason that
>> multi-digit options were disallowed.
>
> As an implementation-specific option, this is multi-digit.
> So there is no ordering problem.

OK, I guess I was assuming that we were trying to escape from
Guideline 3 by saying that "1" and "3" are single-digit options and
"-13" combines them.  If we're not trying to do that, then fine,
Guideline 11 is not a problem.  However, we still run afoul of
Guideline 3.

> Why would the standard warn that some systems might not be standard?

The standard contains several warnings of that sort.  It's a pragmatic
document.  It hasn't been taken over by lawyers (yet :-).

> the standard does indeed mention that the utility syntax guidelines
> might be violated by some standard-conforming implementation

No, it doesn't say that.  It doesn't say that such an implementation
conforms to the standard.