How can I get the PID of a background process in a Xonsh script?

[ading2210]

This is trivial in bash with the $! variable, but I couldn't figure out how to do this in Xonsh.

Something like !(sleep 1 &) doesn't work, as waits until the command completes before returning anything.

If this isn't possible, then how should I start a background process then kill it later without resorting to Python's subprocess library?

[ading2210]

I've found a workaround for this using the xonsh.jobs module:

import xonsh

def get_last_job():
  jobs = list(xonsh.jobs.get_jobs().values())
  if not jobs:
    return None
  last_job = max(jobs, key=lambda x: x["started"])
  return last_job

sleep 10 &
j = get_last_job()

kill @(j["pids"][0])
kill @(j["pids"][0]) #no such process