Check and Kill Process Using a Specific Port

#!/bin/bash

# This script checks if a specified port is in use and offers to kill the process.
# It's useful for web developers to free up ports used by hung development servers.

if [ "$#" -ne 1 ]; then
    echo "Usage: $0 <port_number>"
    echo "Example: $0 3000"
    exit 1
fi

PORT=$1

echo "Checking if port $PORT is in use..."

# Use lsof to find processes listening on the specified port
# -i : selects files by IP address
# -P : inhibits the conversion of port numbers to port names
# -t : produces terse output with process IDs only
PID=$(lsof -i ":$PORT" -t)

if [ -n "$PID" ]; then
    echo "Port $PORT is in use by process with PID: $PID"
    
    # Get process name for better user feedback
    PROCESS_INFO=$(ps -p "$PID" -o comm=)
    echo "Process name: $PROCESS_INFO"
    
    read -rp "Do you want to kill this process (PID: $PID)? (y/N): " response
    
    if [[ "$response" =~ ^[Yy]$ ]]; then
        kill "$PID"
        if [ $? -eq 0 ]; then
            echo "Process $PID (name: $PROCESS_INFO) killed successfully."
        else
            echo "Failed to kill process $PID."
        fi
    else
        echo "Process $PID was not killed."
    fi
else
    echo "Port $PORT is not in use."
fi