bug#15604: [coreutils] [PATCH] md5sum: Add option to ignore non-existant files

[Jim Meyering]

On Mon, Nov 23, 2015 at 5:24 PM, Pádraig Brady <address@hidden> wrote:
> On 23/11/15 16:05, Jim Meyering wrote:
>> On Mon, Nov 23, 2015 at 2:20 PM, Pádraig Brady <address@hidden> wrote:
>>>> I'll push a bit later today.
>>>
>>> Pushed at 
>>> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=v8.24-91-g9fd0662
>>> Marking http://bugs.gnu.org/15604 done
>>
>> Given how this warns/fails when using --check does nothing,
>>
>>   $ :|sha1sum --check
>>   sha1sum: 'standard input': no properly formatted SHA1 checksum lines found
>>   [Exit 1]
>>
>> should using --check with --ignore-missing also warn/fail when it
>> verifies no checksum?
>>
>>   $ :|sha1sum |sed s/-/no-such/ |sha1sum --check --ignore-missing; echo $?
>>   0
>
> It's a fair point, but I see the first error as verifying the
> checksum file itself, and so separate functionality.
>
> Related to this is outputting "MISSING" as well as "OK"
> unless --quiet is specified, though I thought the lack
> of "OK" if no files found would be enough indication
> of an issue in the normal usage?

I think a common expected usage of --ignore-missing would be
the case of an SHA1SUM file listing all possibly-verified files for
which it is common to verify only the one or two downloaded files.
In any invocation that ends up ignoring *all* file names, I would
want a loud warning and failure, to be sure that my eyes (and/or
any tool) notice something is wrong.

The absence of an "OK" is far easier to miss than a diagnostic.
At least a few are often expected to be missing, so I see little
value in emitting "MISSING" diagnostics.