Determining full pathname of output file?

[albertoriva]

I'm writing a pipeline (using Nextflow 21.04.0) in which I need to store in a "native" variable the pathname to a file generated by a process. Something like this:

process Test {
  output:
  file("test.txt") into output_ch

  script:
  var = file("test.txt")
  """
  echo 123 > test.txt
  """
}

The problem is that if I do this, var will contain the path to "test.txt" relative to workflow.launchDir, and NOT to the task's execution directory (which is what instead the file() function in the output definition provides).

Is there a way to accomplish this? I've seen some references in the documentation to task.workDir, but that always returns "null" for me.

Thank you!