[GRASS-user] result from g.copy when layer exists

[Nick Ves]

Since we're talking about grass errors, is there a way to redirect the
warnings/errors ?

e.g. r.mapcalc "..." 2>error.log

On Fri, Jul 19, 2013 at 10:14 AM, Markus Metz
<markus.metz.giswork at gmail.com> wrote:
> On Thu, Jul 18, 2013 at 1:57 PM, Rainer M Krug <Rainer at krugs.de> wrote:
>> Nikos Alexandris <nik at nikosalexandris.net> writes:
>>
>>> Rainer MK wrote:
>>>> >> I am a bit irritated,  ut maybe I don't dee the reasoning behind this:'
>>>
>>>> >> ,----
>>>> >> | RASS 7.0.svn (grass):~ > g.copy rast=MASK,tmp
>>>> >> | WARNING: <tmp> already exists
>>>> >> | [Raster MASK present]
>>>> >> | GRASS 7.0.svn (grass):~ >
>>>> >> `----
>>>
>>>> >> If the layer already exists, shouldn't the command give actually an
>>>> >> error and not only a warning?
>>>
>>>> >> A warning implies for me that the command worked, but maybe something
>>>> >> unexpected could have happened (or happened) - but this one clearly did
>>>> >> not work, as the layer has not been copied?
>>>
>>> Glynn Clements:
>>>> > In GRASS, errors are fatal; the program will be terminated as soon as
>>>> > the error message has been printed.
>>>
>>> Rainer MK:
>>>> Exactly - if e.g. in r.mapcalc an invalid expression is entered,
>>>> r.mapcalc issues the error message and quits.
>>>
>>>> > Each of g.copy's options accept an arbitray number of
>>>> > source+destination pairs, and the various options aren't mutually
>>>> > exclusive (e.g. a single invocation can copy both raster and vector
>>>> > maps).
>>>
>>>> True.
>>>
>>>> > If it can't perform a particular copy for any reason, it generates a
>>>> > warning then moves on to the next item.
>>>
>>>> True - but this does not answer my question. But I looked at cp in bash,
>>>> and it behaves in the same way.
>>>> So I think I have to live with this.
>>>
>>> Just sharing my thoughts about: Imagine copying 1000 maps.  And one is meant
>>> to fail, say the 1st one of them.  You wouldn't, probably, like the copy
>>> process to be interrupted just for one map that failed. Right?
>>
>> Depends: when using in a script, I would like it to fail, as the
>> following commands might give wrong resuls as they would be based on the
>> previous map and not the copied one.
>>
>> Also, in a script this could mean that previous commands did not clean
>> their temporary files properly - other cause for an interruption of the
>> script.
>>
>> When doing it from the command prompt, I would say: just tell me which
>> ones failed - correct.
>>
>> SO the best would be a flag which says "error on map exists".
>
> The other way around: you can enforce copying (overwrite existing
> maps) with g.copy --o
>
> Markus M
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