[GRASS-dev] How to get stop a script with an error in a function

GRASS GRASS developer
,
1

*Glynn Clements* wrote:

Check the exit code from the command. Commands should use a non-zero
exit code if there was an error.

It would help to know exactly how the command is being run.

Hi,
You are absolutely right :slight_smile:
Among others, I'm using:
grass.run_command("r.in.gdal", flags= 'k', overwrite = 'o', input = src_file, output = target_file)

Shall I do something like
check_process=grass.run_command("r.in.gdal", flags= 'k', overwrite = 'o', input = src_file, output = target_file) if check_process=0:
   gdal_fatal (_("ERROR"))

?

Thanks
Antonio

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2

Hi,

2010/10/15 António Rocha <antonio.rocha@deimos.com.pt>:

check_process=grass.run_command("r.in.gdal", flags= 'k', overwrite = 'o',
input = src_file, output = target_file) if check_process=0:
gdal_fatal (_("ERROR"))

no, '0' means success, non-zero code is usually used for failure. Also
use '==' in conditions, so

ret = grass.run_command(...)
if ret != 0:
    grass.fatal('error')

Martin

--
Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa

3

[keep discussion in ML]

2010/10/15 António Rocha <antonio.rocha@deimos.com.pt>:

Thanks... You are right Zero is for success.
By the way, if a GRASS gunction, that I'm using through grass.run_command
is, prints something in Command Output, how can I "get" it in order to use
it?

try grass.read_command [1].

Martin

[1] http://grass.osgeo.org/programming7/namespacegrass_1_1script_1_1core.html#a7cf2b8f9c0c14e2e9c23acdfe9178433

--
Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa

4

António Rocha wrote:

> Check the exit code from the command. Commands should use a non-zero
> exit code if there was an error.
>
> It would help to know exactly how the command is being run.
>
>

Hi,
You are absolutely right :slight_smile:
Among others, I'm using:
grass.run_command("r.in.gdal", flags= 'k', overwrite = 'o', input = src_file, output = target_file)

  if grass.run_command(...) != 0:
      grass.fatal(...)

run_command and write_command return the exit code.

start_command, pipe_command, and feed_command return the Popen object;
you can check its .returncode attribute once it has terminated.

read_command and parse_command return the data written to the child's
stdout; there isn't any mechanism to retrieve the exit status for
these. OTOH, read_command is trivial to implement yourself if you need
this.

--
Glynn Clements <glynn@gclements.plus.com>