k6

#!/usr/bin/env sh

# Start the program in the background
exec "$@" &
program_pid=$!

# Silence warnings from here on
exec >/dev/null 2>&1

# Read from fd[3] in the background and send SIGTERM to running program
# when it closes. Fd[3] is the file descriptor used by the BEAM to
# communicate with this process (kind-of a fake stdin),
# since we are using :nouse_stdio with our port.
{
  while read _ <&3; do :; done
  kill -TERM $program_pid
} &

waiter_pid=$!

# Clean up
wait $program_pid
ret=$?

kill -KILL $waiter_pid

exit $ret