how to run a shell script file from php

Question

i am using apache based application where front end is php and backend as java through socket am sending requests from php to java.

i am trying to run a shell script file in php and script contains killing old java process and will start new java process but it not working

This is my script:

/opt/APIController/RSN_API_Controller_start.sh

#!/bin/bash

service cassandra start

service httpd start

prid=$(ps aux| egrep '[R]SN_API_Controller.jar' | awk '{print $2}')

if [ -z "$prid" ]
then
        echo "No process to kill"
else
        kill -9 $prid
        echo "Successfully service stopped"
fi

pridold=$(ps aux| egrep '[R]snBlacklist.jar' | awk '{print $2}')

if [ -z "$pridold" ]
then
        echo "No process to kill"
else
        kill -9 $pridold
        echo "Successfully service stopped old jar file"
fi

nohup java -Djsse.enableSNIExtension=false -jar RSN_API_Controller.jar &

echo "Successfully service started"

and my php code for executing this script is

<?php
     //some lines
     shell_exec('sh /opt/APIController/RSN_API_Controller_start.sh');
     //some lines
?>

based on a button click it will execute this script, manually script killing and start new java process but through php script file not executing properly and am not able to find the exact issue.

please help me with this