Startup script for running daemon java process in docker and tail log file

startup.sh

#!/usr/bin/env bash

# Script to run a process that runs in the background, 
# then tail the log file in the forground. 
# Useful for running apps in Docker container  like subsonic, spark or apache.
# Author: [email protected]

function cleanup {
  kill `pidof tail` 2>/dev/null
  kill `pidof java` 2>/dev/null
}
trap cleanup EXIT
trap cleanup INT

cleanup

# Set file to tail
WATCH_FILE="/var/log/messages"

### Execute java daemonized program
echo "Hello Daemon"

RES=$?
if [[ ! ${RES} -eq 0 ]]; then
  echo "ERROR: Exit code was ${RES}"
  exit 1
fi

while ! stat ${WATCH_FILE} >/dev/null 2>&1; do
  echo "Waiting for ${WATCH_FILE}"
  sleep 1
done

tail -f ${WATCH_FILE} &

while kill -0 `pidof java` 2>/dev/null; do
  sleep 0.5
done