Running java program as a linux service

Recently, I was wondering about how the programs are running as a service in Linux. After a little googling,  i learned it is very simple. All we have to do is just write a script that starts, stops and restarts the program and register this script as a Linux service. Let me tell the scenario.

I have just written a simple java program that connects a database and sends cpu, memory and disk I/O information for monitoring the server performance. It is running on the Fedora Linux operating system. Java version 1.6.0_03. Java program is located under /LinuxAgent directory.

Thanks for google i found this script and changed the necessary parameters (Program path, java launcher, service name etc.)

Here is the contents of the script;

#!/bin/sh

# description: LinuxAgent

scriptFile=$(readlink -fn $(type -p $0))

scriptDir=$(dirname $scriptFile)

applDir="$scriptDir"

serviceName="LinuxAgent"

serviceNameLo="LinuxAgent"

serviceGroup="root"

pidFile="/var/run/$serviceNameLo.pid"

serviceLogFile="/var/log/$serviceNameLo.log"

javaCommand="java"

javaArgs="-jar /LinuxAgent/LinuxAgent.jar"

javaCommandLine="$javaCommand $javaArgs"

javaCommandLineKeyword="LinuxAgent"

maxShutdownTime=15

function makeFileWritable {

local filename="$1"

touch $filename || return 1

chgrp $serviceGroup $filename || return 1

chmod g+w $filename || return 1

return 0; }

function checkProcessIsRunning {

local pid="$1"

if [ -z "$pid" -o "$pid" == " " ]; then return 1; fi

if [ ! -e /proc/$pid ]; then return 1; fi

return 0; }

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; }

function startServiceProcess {

cd $applDir || return 1

rm -f $pidFile

makeFileWritable $pidFile || return 1

makeFileWritable $serviceLogFile || return 1

cmd="nohup $javaCommandLine >>$serviceLogFile 2>&1 & echo \$! >$pidFile"

#sudo -u $serviceUser $SHELL -c "$cmd" || return 1

$SHELL -c "$cmd" || return 1

sleep 0.1

pid="$(<$pidFile)"

if checkProcessIsRunning $pid; then :; else

echo "$serviceName service can not be started, log file $serviceLogFile ."

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 $pidFile

return 0

fi

sleep 0.1

done

echo "$serviceName can not stop in $maxShutdownTime , 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 $pidFile

return 0

fi

sleep 0.1

done

echo "Error: $serviceName can not stop in $maxShutdownTime+$killWaitTime "

return 1; }

function getServicePID {

if [ ! -f $pidFile ]; then return 1; fi

pid="$(<$pidFile)"

checkProcessIsRunning $pid || return 1

checkProcessIsOurService $pid || return 1

return 0; }

function startService {

getServicePID

if [ $? -eq 0 ]; then echo "$serviceName is already running"; return 0; fi

echo "$serviceName is starting"

startServiceProcess

if [ $? -ne 0 ]; then return 1; fi

return 0; }

function stopService {

getServicePID

if [ $? -ne 0 ]; then echo "$serviceName is not running"; return 0; fi

echo "$serviceName is stopping"

stopServiceProcess

if [ $? -ne 0 ]; then return 1; fi

return 0; }

function checkServiceStatus {

echo -n "$serviceName is controlling: "

if getServicePID; then

echo "LinuxAgent is running"

else

echo "LinuxAgent is not running"

fi

return 0; }

function main {

case "$1" in

start)

startService

;;

stop)

stopService

;;

restart)

stopService && startService

;;

status)

checkServiceStatus

;;

*)

echo "Usage: $0 {start|stop|restart|status}"

exit 1

;;

esac

}

main $1

Script must be saved under the /etc/inid.d directory and execute permission must be given;

$ chmod 755 /etc/init.d/LinuxAgent

Chkconfig utility registers the service;

$ chkconfig –add LinuxAgent

$ chkconfig LinuxAgent –level 12345 on

Now service is created and we start and stop service with these commands;

$ service LinuxAgent start

$ service LinuxAgent stop

To learn the status of the service;

$ service LinuxAgent status