A simple application runner for managing the start/stop operations of binary executables on a Linux virtual machine (VM)

run.sh

#!/bin/bash

##################################################
# Run script for applications
# Usage: ./run.sh start
#        ./run.sh restart
#        ./run.sh stop
# Features:
# - Auto-detect application name and port (based on folder name) and binary (last by creation date)
# - Automatically checks if the application is running, shows its last logs
##################################################

# General variables (no need to change)
APP_NAME=$(basename "$(pwd)") # as a directory name
APP_PORT=$((8000 + (0x$(echo -n "$APP_NAME" | md5sum | awk '{print $1}' | cut -c1-8) % 1001))) # 8000-9000 based on the app name hash
LOG_FILE="log-${APP_NAME}.txt"
PID_FILE="${APP_NAME}.pid"
# Pick up variables from .env file if exists
[ -f .env ] && export $(grep -v '^#' .env | xargs)

# ❗️ Application specific variables, make sure to change them
BIN=$(find . -maxdepth 1 -type f -name "*.jar" | sort -nr | head -n 1) || { echo "ERROR: Binary not found!"; exit 1; } # last by creation date
CMD="java -jar '$BIN' --server.port=$APP_PORT"



# General functions (no need to change)...
start() {
    if [ -f "$PID_FILE" ] && ps -p "$(cat "$PID_FILE")" > /dev/null 2>&1; then
        echo "⚠️ Application $APP_NAME is already running."
        exit 1
    fi

    echo "Application $APP_NAME is starting..."
    echo "🚀 Command: $CMD"

    nohup bash -c "$CMD" >> "$LOG_FILE" 2>&1 &
    echo $! > "$PID_FILE"

    sleep 3
    logs

    check
}

stop() {
    if [ ! -f "$PID_FILE" ]; then
        echo "PID file not found."
        exit 1
    fi
    PID=$(cat "$PID_FILE")
    kill "$PID"; sleep 2
    ps -p "$PID" > /dev/null 2>&1 && kill -9 "$PID"
    rm -f "$PID_FILE"
    echo "🛑 Application $APP_NAME stopped."
}

restart() {
    stop
    start
}

logs() {
    if [ -f "$LOG_FILE" ]; then
        tail -n 100 "$LOG_FILE"
        echo "📔 To watch logs in real-time: tail -f $LOG_FILE -n 500"
    else
        echo "⚠️ Log file not found."
    fi
}

check() {
    if [ -f "$PID_FILE" ]; then
        PID=$(cat "$PID_FILE")
        if ps -p "$PID" > /dev/null 2>&1; then
            echo "✅ Application $APP_NAME is running with PID $PID."
        else
            echo "⚠️ Application $APP_NAME is not running, but PID file exists."
        fi
    else
        echo "🛑 Application $APP_NAME is not running."
    fi
}

case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    restart)
        restart
        ;;
    logs)
        logs
        ;;
    check)
        check
        ;;
    *)
        echo "Usage: $0 {start|stop|restart|logs|check}"
        exit 1
        ;;
esac