process_ctl, take 2

gistfile1.txt

#!/usr/local/bin/bash

pid_file="/Users/jcc/pid_file"
command="ping -i 60 localhost"

###############################################################################
##         user customization below this should not be required              ##
###############################################################################
function start {
   echo "starting..."
   #$command
   $command &
   pid=$!
   echo $pid > $pid_file
   echo "process id is $pid"
}

function stop {
   echo "stopping..."
   kill $pid
   #check to see if process died immediately
   updateProcessStatus

   #otherwise wait for it to die
   while [ ! -z "$pid" ]
   do
      echo "waiting for process $pid to stop..."
      sleep 2
      updateProcessStatus
   done
   rm $pid_file
   pid=""
   echo "process $pid stopped"
}


# update the global variable to indicate status
function updateProcessStatus {
  if [ ! -z "$pid" ]
  then
    #echo "checking for process $pid..."
    #BSD/POSIX doesn't support --no-headers
    count=$(ps -o %cpu= -p $pid|wc -l)
    #count=$(ps -lfhp $pid|wc -l)
    if [ "$count" -eq 0 ]
    then
      pid=""
    fi
  fi
}


function checkForAbandonedPidFile {
  if [ ! -z "$pid" ]
  then
    #BSD/POSIX doesn't support --no-headers
    count=$(ps -o %cpu= -p $pid|wc -l)
    #count=$(ps -lfhp $pid|wc -l)
    if [ "$count" -eq 0 ]
    then
      echo "WARNING: detected abandoned PID file. removing it now..."
      pid=""
      rm $pid_file
    fi
  fi
}


function checkForBlankPidFile {
  if [ -e "$pid_file" -a -z $"pid" ]
  then
    echo "WARNING: PID file found but with blank PID. removing it now..."
    rm $pid_file
  fi
}


function initPID {
  if [ ! -e "$pid_file" ]
  then
    # a little risky, but w/o a PID, assume process is not running
    pid=""
  else
    pid=$(cat "$pid_file")
    echo "process ID is $pid"
  fi  
}

initPID

checkForBlankPidFile

checkForAbandonedPidFile

case "$1" in
'start')
        if [ -z "$pid" ]
        then
            start
        else
            echo "process $pid already running"
        fi
        ;;

'stop')
        if [ ! -z "$pid" ]
        then
            stop
        else
            echo "process is not running"
        fi
        ;;
'status')
        if [ ! -z "$pid" ]
        then
            echo "process $pid is running"
        else
            echo "process is not running"
        fi
        ;;
*)
        echo "Usage: logstash_apache_logs { start | stop | status }"
        ;;
esac
exit 0