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

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

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.

Cheers,
Alistair