Creating your shell script to start/stop a Java application on Linux

Creating your start and stop script

With this script you can turn your jar file into a service on linux. 

Change the MATH constant to the name of your application and make sure you are correctly specifying 
the locationsof the files used in the variables.

For the correct operation of the script install it in the directory init.d and release its access as below:

chmod 755 *your_script*

service.bash

#!/bin/bash

### BEGIN INIT INFO
# Provides:                 MATH
# Required-Start:           $java $pgrep
# Required-Stop:            $java $pgrep
# Short-Description:        Start and stop MATH service.
# Description:              MATH it's a java appplication example
# Date-Creation:            2018-09-26
# Date-Last-Modification:   2018-09-26
# Author:                   Matheus Sant"Anna de Oliveira
### END INIT INFO

# Variables
APPDIR=/opt/MATH
PGREP=/usr/bin/pgrep
JAVA=/usr/bin/java
MATHJARFILE=/MATH.jar
ZERO=0
OKMSG=OK
MATHPORT=3131

#Colors
RED='\033[1;31m'
GREEN='\033[1;32m'
YELLOW='\033[1;33m'
BLUE='\033[1;34m'
NC='\033[0m' #No Color

# Start the MATH
start() {
    echo ""		
    echo "Starting MATH..."
    #Verify if the service is running
    $PGREP -f MATH > /dev/null
    VERIFIER=$?
    if [ $ZERO -eq $VERIFIER ]
    then
        echo -e "The service is ${YELLOW}already${NC} running"
    else
        #Run the jar file MATH service
        $JAVA -jar "-Dfile.encoding=UTF-8" $APPDIR$MATHJARFILE q > /dev/null 2>&1 &
        #sleep time before the service verification
        sleep 3
        #Verify if the service is running
        $PGREP -f MATH  > /dev/null
        VERIFIER=$?
        if [ $ZERO -eq $VERIFIER ]
        then
            echo -e "Service was ${GREEN}successfully${NC} started"
        else
            echo -e "${RED}Failed${NC} to start service"
        fi
    fi
    echo
}

# Stop the MATH
stop() {
    echo ""		
    echo "Stopping MATH..."
    #Verify if the service is running
    $PGREP -f MATH > /dev/null
    VERIFIER=$?
    if [ $ZERO -eq $VERIFIER ]
    then        
		#Kill the pid of java with the service name
		kill -9 $($PGREP -f MATH)
		#Sleep time before the service verification
		sleep 3
		#Verify if the service is running
		$PGREP -f MATH  > /dev/null
		VERIFIER=$?
		if [ $ZERO -eq $VERIFIER ]
		then
			echo -e "${RED}Failed${NC} to stop service"
		else
			echo -e "Service was ${GREEN}successfully${NC} stopped"
		fi        
    else
        echo -e "The service is ${YELLOW}already${NC} stopped"
    fi
    echo
}

# Verify the status of MATH
status() {
    echo ""		
    echo "Checking status of MATH..."
    img
    #Verify if the service is running
    $PGREP -f MATH > /dev/null
    VERIFIER=$?
    if [ $ZERO -eq $VERIFIER ]
    then
        echo -e "Service is ${GREEN}running${NC}"        
    else
        echo -e "Service is ${RED}stopped${NC}"
    fi
    echo
}

# Main logic from script
case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    status)
        status
        ;;
    restart|reload)
        stop
        start
        ;;
  *)
    echo "${RED}Invalid arguments${NC}"
    echo " Usages: $0 ${BLUE}{ start | stop | status | restart | reload }${NC}"
    exit 1
esac
exit 0