Martin,

Thank you very much for the answer! Unfortunately I'm still stuck :-( Please take a look at the following code and tell me why it's still asynchronous. It display properly messages: "testFunct" and then "end of testFunct", but it never reach the .then or .done.
Thank you in advance!

    function testFunc() {
     alert("testFunc");
     lic = cockpit.spawn(["/usr/share/cockpit/testSoftware/connectExternalSystem"], {
     directory: "/usr/share/cockpit/testSoftware",
     err: "message"
     })
     .then(function() {
     alert("in .then of testFunc. Error: "+message);
            })
            .done(function() {
     alert("in .done of testFunc. Error: "+message);
     });
     alert("end of testFunc");
    }

czw., 10 sty 2019 o 09:02 Martin Pitt <martin@piware.de> napisał(a):
Hello Magik,

. [2019-01-09 21:51 +0100]:
> I'm C programmer learning now Cockpit. My problem is as follows: for some
> of the operation I must use external helper and I must wait for it output.
> The cockpit.spawn() function returns the promise, which is non-blocking
> operation (as expected). How can I make it work as blocking one? Which
> mean: the rest of the code in the function should be done after receiving
> full output of the cockpit.spawn (done() or fail())

This is a common pitfal when coming from the world of synchronous programming
languages (such as C or Python) and starting with asynchronous JavaScript.
Daniel's await proposal can certainly help to make async code look like it was
written in a sync style; but honestly, it's really best to let go of this
pattern when writing JS.

So instead of

  output = cockpit.spawn(..).make_this_magically_sync();
  followup_action(output);

actually use JavaScript promises as they are intended:

  cockpit.spawn(..)
      .then(output => {
          followup_action(output);
      })
      .catch(err => {
          console.error(err);
      });

i. e. organize the stuff that depends on the result into promise handlers.

Martin
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