CODEWITHSUNDEEP
node.jswindowsscheduled-tasks
Tomáš Hübelbauer
Tomáš Hübelbauer

Reputation: 10664

Node's spawn/exec not working when called from a scheduled Windows task

I'm facing a very odd issue where I have a Node script which invokes a process, it looks like this:

  // wslPath declared here (it's a shell file)
  const proc = cp.spawn('ubuntu.exe', ['run', wslPath]);

  let stdout = '';
  proc.stdout.on('data', data => stdout += data.toString());

  let stderr = '';
  proc.stderr.on('data', data => stderr += data.toString());

  return await new Promise((resolve, reject) => {
    proc.on('exit', async code => {
      await fs.remove(winPath);

      if (code) {
        reject({ code, stdout, stderr });
      }

      resolve({ stdout, stderr });
    });
  });

As you can see, the script invokes WSL. WSL is enabled on the computer. When I run this script manually, it works fine. When I log in to the computer the script is at using RDP from another computer and run it with the same credentials, it works fine as well. But when the script is invoked from a scheduled task which also runs with the same credentials, the spawn call returns:

(node:4684) UnhandledPromiseRejectionWarning: Error: spawn UNKNOWN
    at ChildProcess.spawn (internal/child_process.js:394:11)
    at Object.spawn (child_process.js:540:9)

I verified the user is the same by logging require('os').userInfo() and require('child_process').spawnSync('whoami', { encoding: 'utf8' }) and it returns the same in all three cases.

I assume it is because ubuntu.exe is not being found, but I don't know why that would be as the user is the same in all three cases.

What could be the reason for this and how can I debug this further?

Upvotes: 0

Views: 1314

Answers (1)

jfriend00
jfriend00

Reputation: 708036

The Windows Task Scheduler allows you to specify a user to run as (for privilege reasons), but does not give you the environment (PATH and other environment variables) that are configured for that user.

So, when running programs from the Windows Task Scheduler, it's important to not make any assumptions about what's in the environment (particularly the PATH). If my program depends on certain things in the environment, I will sometimes change my Task to be a .BAT file that first sets up the environment as needed and then launch my program from there.

Among other things, the simplest way to not rely on the path is to specify the full path to the executable you are running rather than assuming it will be found in the path somewhere. But, you also need to make sure that your executable can find any other resources it might need without any environment variables or you need to configure those environment variables for it before running.

Upvotes: 1

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