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bug#21416: "--" syntax for ignoring flags doesn't seem to work right wit
From: |
Eric Blake |
Subject: |
bug#21416: "--" syntax for ignoring flags doesn't seem to work right with GNU /bin/echo |
Date: |
Fri, 4 Sep 2015 16:05:49 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 09/04/2015 01:30 PM, Robert "Finny" Merrill wrote:
> unicasting so it doesn't reopen the bug:
[re-adding the list with permission]
The bug-tracker is perfectly fine with adding additional comments even
to a closed bug; merely replying doesn't reopen a bug report.
>
> If POSIX says not to recognize "--" doesn't "not recognize" mean it
> shouldn't do anything at all? In that case, you're not actually
> following it since -- causes different behavior :)
You've quoted incomplete context, which changed the meaning.
>> http://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html
>>
>> "The echo utility shall not recognize the "--" argument in the
>> manner specified by Guideline 10 of XBD Utility Syntax Guidelines; "--"
>> shall be recognized as a string operand."
>>
>> "Implementations shall not support any options."
It's not "shall not be recognized [ever]", but "shall not be recognized
in the manner [common to most utilities]. The very next phrase says
that it "shall be recognized as a string operand".
Or put another way, as a special case for the 'echo' utility, '--' shall
be treated the same as any other argument, and always be output
literally, rather than being recognized as the special elided
end-of-options marker, because 'echo' does not understand options (at
least when POSIX rules are in effect).
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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bug#21416: "--" syntax for ignoring flags doesn't seem to work right with GNU /bin/echo, Bob Proulx, 2015/09/04