Re: [gscan2pdf-help] Exit status of user defined tools?

[Alistair G. <akg...@gm...>]

On 14 March 2017 at 17:06, Alistair Grant <akg...@gm...> wrote:
> Hi Jeff,
>
> On 14 March 2017 at 16:58, Jeff <jf...@po...> wrote:
>> On 14/03/17 16:37, Alistair Grant wrote:
>>> Is the exit status of user defined tools checked?  And where does stderr go?
>>
>> No and nirvana, ATM.
>>
>> The trouble is that tools have all sorts of different ideas on what
>> should be returned and what should end up in stderr.
>>
>>> I'm currently trying to get gscan2pdf running inside a docker image.
>>> It appears to be mostly working, I can scan, delete pages, renumber,
>>> save, etc., but attempting to running textcleaner as a user defined
>>> task fails:
>>>
>>> DEBUG - Free space in /tmp/gscan2pdf-pcQB (Mb): 42126.60546875 (warning at 10)
>>> INFO - textcleaner -e stretch -f 23 -o 6 -T
>>> /tmp/gscan2pdf-pcQB/QZp0Rf3RmN.pnm /tmp/gscan2pdf-pcQB/lPP177XrQd.pnm
>>> ERROR - Exception 425: improper image header
>>> `/tmp/gscan2pdf-pcQB/lPP177XrQd.pnm' @ error/pnm.c/ReadPNMImage/282
>>> ERROR - Error reading /tmp/gscan2pdf-pcQB/lPP177XrQd.pnm: Exception
>>> 425: improper image header `/tmp/gscan2pdf-pcQB/lPP177XrQd.pnm' @
>>> error/pnm.c/ReadPNMImage/282.
>>>
>>> The improper image header is raised because the output file,
>>> lPP177XrQd.pnm, is 0 bytes long.
>>>
>>> If I copy and paste the textcleaner command in a separate shell it
>>> succeeds, i.e. I can view lPP177XrQd.pnm successfully.
>>
>> It sounds to me that there is a race condition. i.e. textcleaner returns
>> before the output file is written.
>>
>> I take it that it all works fine outside the Docker image?
>
> Yep, it was working in my previous environment (I've just wiped the
> drive on my laptop and re-installed the OS, so I don't have access to
> the old environment).
>
>> If so, it is going to be hard to debug.
>
> But this has reminded me of using wrapper scripts to debug, so I'll try that.
>
> Thanks for such a quick response.

Just FYI: textcleaner assumes that the current working directory is
writeable, and it wasn't inside docker.  I'll leave the wrapper script
in place that changes the working directory.

Thanks again,
Alistair