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Re: option abbreviation exceptions

From: Jim Meyering
Subject: Re: option abbreviation exceptions
Date: Mon, 29 Dec 2008 18:02:39 +0100

Eric Blake <address@hidden> wrote:

> Eric Blake <ebb9 <at> byu.net> writes:
>>  Some of these programs recognize the @option{--help} and @option{--version}
>> -options only when one of them is the sole command line argument.
>> +options only when one of them is the sole command line argument.  For
>> +these programs, abbreviations of the long options are not recognized.
> In subsequent testing, I realized this is not entirely true.  Should I work on
> a followup patch that makes this sentence true?

Simplest might be to change "not recognized" to "not always recognized".

> For example,
> $ /bin/echo --help --version | head -n1
> --help --version
> $ /bin/echo --help | head -n1
> Usage: /bin/echo [OPTION]... [STRING]...
> $ /bin/echo --he | head -n1
> Usage: /bin/echo [OPTION]... [STRING]...
> $ /bin/echo -n -e hi\\n | head -n1
> hi
> Certainly some inconsistent behavior.  echo takes multiple arguments, but only
> when they are the short options -[neE] (I guess it's okay that they don't have
> long-option variants?).

Yes, I think so.  coreutils' echo is so old and rarely used
that it doesn't matter.  People should be using printf instead.

> But when --help or --version is present, echo acts
> like it takes exactly one argument.  The usage text doesn't really portray
> that.  The other thing that is awkward is that we are recognizing
> abbreviations; it seems like it would make more sense for "echo --he" to
> output "--he" rather than the help text.  POSIX isn't much help here, either,
> as it only specifies that portable apps can't use -n (but says nothing about -
> e), and we are already violating the (lame) POSIX requirement that -e be on by
> default, thus giving no guidance on whether we are better off requiring the
> user to write "/bin/echo -ne" instead of "/bin/echo -n -e" when they want both
> options.
> Another case in point:
> $ /bin/[ --help me | head -n1
> /bin/[: missing `]'
> $ /bin/[ --help | head -n1
> Usage: test EXPRESSION
> $ /bin/[ --hel | head -n1
> Usage: test EXPRESSION
> Should the last example also complain about missing `]', rather than printing
> help text?

test and [ have always had a conflicted relationship
with --help/--version.

Making [ accept no abbreviations does seem like it'd be an improvement.

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