starting server with nohup and redirecting input, output

Question

I have a init.d script that starts a python socket server. Because I want this to run as a daemon, I use nohup to start it. I also want to redirect stdout and stderr to a log file. My problem is that I am also trying to capture the PID of the process to save to a file, which I can't seem to do.

# Start server
echo "Starting server."
nohup ${PROGDIR}/${PROGNAME} -l $IPADDR >>${LOGDIR}/${OUTLOG} 2>>${LOGDIR}/${OUTLOG} </dev/null &
PID=$!

This was able to capture the PID, but redirection did not work. (Was I redirecting nohup rather than the program?)

Next I tried something like:

nohup /bin/bash -c '...'

But I lost the PID. At this point, I seemed to be getting the PID of nohup /bin/bash -c. As I am not very familiar with shell scripts, I thought I would ask for help before I shoot myself in the foot.

So my question is, how can I capture the PID and redirect the server output to the logfile? I am on a debian (raspberry pi) and am writing an init script using rc-update.d.

Answer 1

If you're on a Debian variant, you have start-stop-daemon available, which does all this for you in a much cleaner way. In particular:

start-stop-daemon --make-pidfile --pidfile "$PIDFILE" --background \
    --no-close --exec "${PROGDIR}/${PROGNAME}" --start -- -l "$IPADDR" \
    >> "${LOGDIR}/${OUTLOG}" 2>> "${LOGDIR}/${OUTLOG}" </dev/null

should be pretty close to what you want. It puts the PID in a file instead of into a variable, but you can of course read it back out into a variable easily.