Execute shell-command on file upload (hook)

Hi,
when i upload a file i want to execute some shell commands to work with this file.

in my case, when i upload a GPX file, there should be called a command-line i made (several commands piped one after each other) to generate some special files i want to use later.

for example:
gpsbabel -i gpx -f input.gpx -x simplify,crosstrack,error=0.002k -o gpx -F - | python gpx2svg | svgo -i - -o - | gzip -f > output.svgz

i made a hook for upload in config.php to test. this one works:

kirby()->hook('panel.file.upload', 'gpxExtract');
kirby()->hook('panel.file.replace', 'gpxExtract');

function gpxExtract($file) {
  try {
    // check file type
    if ($file->extension() == 'gpx') {

    f::write(kirby()->roots()->index() .'/log.txt', $file->filename());

      }
  } catch (Exception $e) {
      return response::error($e->getMessage());
  }
}

then i tried to exec or shell_exec my commandline (instead of the log-write commandline). but i can’t get it to work.

maybe it’s a syntax-problem. (i tried several things, without success)

thx in advance

Is exec() enabled on your server?

yes it is.

i was testing a little bit more in detail now… it seems to be a path-problem.

sorry =)

EDIT:
yes… path-problem. everything works as expected, now