How can I check to see if a process is stopped from the command-line?

You can check whether the process is in stopped state, T is ps output.

You can do:

[ "$(ps -o state= -p PID)" = T ] && kill -CONT PID

• [ "$(ps -o state= -p PID)" = T ] tests whether the output of ps -o state= -p PID is T, if so send SIGCONT to the process. Replace PID with the actual process ID of the process.

Another way would be

pid=1
status=`cat /proc/$pid/wchan`
if [ "$status" == "do_signal_stop" ] ; then
  echo "$pid sleeps: $status"
else
  echo "$pid does not sleep: $status"
fi