BASH: Script to determine whether an application is running.

app-status.sh

#!/bin/bash --

# File containing the process ID of the application, written by the application
PID_FILE='app.pid'

# The process name or some string unique to the application's process
PROCESS_NAME="java -Dspring.config.location=${HOME}/application.properties"

[[ $# -gt 0 && $1 = '-v' ]] && VERBOSE=1

if [[ -f ${PID_FILE} ]]; then
  [[ ${VERBOSE} ]] && echo "${PID_FILE} found"
  PID=$(cat "${PID_FILE}")
else
  [[ ${VERBOSE} ]] && echo "${PID_FILE} not found"
fi

if [[ ! ${PID} ]]; then
  [[ ${VERBOSE} ]] && echo "No process ID.  Searching processes by name."
  PID=$(pgrep -f "${PROCESS_NAME}")
fi

if [[ ${PID} ]]; then
  echo "Running: process ID = ${PID}"
  exit $(true)
else
  echo 'Not running: process ID not found'
  exit $(false)
fi