#!/bin/bash
#
# bookhub
#
# chkconfig: - 64 36
# description:  Books Hub Server.
# processname: bookhub
# config: /etc/bookshub/server.cfg
# pidfile: /home/sakhsl/bookhub/bookhub.pid

# Set this to your Java installation
JAVA_HOME=/usr/lib/java
 
serviceNameLo="bookhub"                                    # service name with the first letter in lowercase
serviceName="Books Hub Server"                             # service name
serviceUser="sakhsl"                                       # OS user name for the service
serviceGroup="sakhsl"                                      # OS group name for the service
serviceUserDir="/home/$serviceUser/$serviceNameLo"
applDir="$serviceUserDir"                                  # home directory of the service application
serviceLogFile="$serviceUserDir/$serviceNameLo.log"        # log file for StdOut/StdErr
servicePidFile="$serviceUserDir/$serviceNameLo.pid"        # name of PID file (PID = process ID number)
maxShutdownTime=15                                         # maximum number of seconds to wait for the daemon to terminate normally
javaExe="$JAVA_HOME/bin/java"                              # file name of the Java application launcher executable
javaArgs="-jar $applDir/$serviceNameLo.jar"                # arguments for Java launcher
javaCommandLine="$javaExe $javaArgs"                       # command line to start the Java service application
javaCommandLineKeyword="$serviceNameLo.jar"                # a keyword that occurs on the commandline, used to detect an already running service process and to distinguish it from others
 
# Makes the file $1 writable by the group $serviceGroup.
function makeFileWritable {
   local filename="$1"
   touch $filename || return 1
   chgrp $serviceGroup $filename || return 1
   chmod g+w $filename || return 1
   return 0; }
 
# Returns 0 if the process with PID $1 is running.
function checkProcessIsRunning {
   local pid="$1"
   if [ -z "$pid" -o "$pid" == " " ]; then return 1; fi
   if [ ! -e /proc/$pid ]; then return 1; fi  
   return 0; 
}
 
# Returns 0 if the process with PID $1 is our Java service process.
function checkProcessIsOurService {
   local pid="$1"
   if [ "$(ps -p $pid --no-headers -o comm)" != "$javaCommand" ]; then return 1; fi
   grep -q --binary -F "$javaCommandLineKeyword" /proc/$pid/cmdline
   if [ $? -ne 0 ]; then return 1; fi
   return 0; 
}
 
# Returns 0 when the service is running and sets the variable $pid to the PID.
function getServicePID {
   if [ ! -f $servicePidFile ]; then return 1; fi
   pid="$(<$servicePidFile)"
   checkProcessIsRunning $pid || return 1
   checkProcessIsOurService $pid || return 1
   return 0; 
}
 
function startServiceProcess {
   cd $applDir || return 1
   rm -f $servicePidFile
   makeFileWritable $servicePidFile || return 1
   makeFileWritable $serviceLogFile || return 1
   cmd="nohup $javaCommandLine >>$serviceLogFile 2>&1 & echo \$! >$servicePidFile"
   su -m $serviceUser -s $SHELL -c "$cmd" || return 1
   sleep 0.1
   pid="$(<$servicePidFile)"
   if checkProcessIsRunning $pid; then :; else
      echo -ne "\n$serviceName start failed, see logfile."
      return 1
   fi
   return 0; }
 
function stopServiceProcess {
   kill $pid || return 1
   for ((i=0; i<maxShutdownTime*10; i++)); do
      checkProcessIsRunning $pid
      if [ $? -ne 0 ]; then
         rm -f $servicePidFile
         return 0
         fi
      sleep 0.1
      done
   echo -e "\n$serviceName did not terminate within $maxShutdownTime seconds, sending SIGKILL..."
   kill -s KILL $pid || return 1
   local killWaitTime=15
   for ((i=0; i<killWaitTime*10; i++)); do
      checkProcessIsRunning $pid
      if [ $? -ne 0 ]; then
         rm -f $servicePidFile
         return 0
         fi
      sleep 0.1
      done
   echo "Error: $serviceName could not be stopped within $maxShutdownTime+$killWaitTime seconds!"
   return 1; }
 
function startService {
   getServicePID
   if [ $? -eq 0 ]; then echo -n "$serviceName is already running"; RETVAL=0; return 0; fi
   echo -n "Starting $serviceName   "
   startServiceProcess
   if [ $? -ne 0 ]; then RETVAL=1; echo "failed"; return 1; fi
   echo "started PID=$pid"
   RETVAL=0
   return 0; }
 
function stopService {
   getServicePID
   if [ $? -ne 0 ]; then echo -n "$serviceName is not running"; RETVAL=0; echo ""; return 0; fi
   echo -n "Stopping $serviceName   "
   stopServiceProcess
   if [ $? -ne 0 ]; then RETVAL=1; echo "failed"; return 1; fi
   echo "stopped PID=$pid"
   RETVAL=0
   return 0; }
 
function checkServiceStatus {
   echo -n "Checking for $serviceName:   "
   if getServicePID; then
    echo "running PID=$pid"
    RETVAL=0
   else
    echo "stopped"
    RETVAL=3
   fi
   return 0; }

function main {
   RETVAL=0
   case "$1" in
      start)                                               # starts the Java program as a Linux service
         startService
         ;;
      stop)                                                # stops the Java program service
         stopService
         ;;
      restart)                                             # stops and restarts the service
         stopService && startService
         ;;
      status)                                              # displays the service status
         checkServiceStatus
         ;;
      *)
         echo "Usage: $0 {start|stop|restart|status}"
         exit 1
         ;;
      esac
   exit $RETVAL
}
 
main $1