BASH

Checking if a TCP Port is Listening for Service Availability

Utilize this Bash snippet to quickly verify if a specific TCP port is actively listening on a host, crucial for checking web server or database service availability and diagnostics.

#!/bin/bash
HOST="localhost"
PORT="80" # Example: HTTP port

echo "Checking if $HOST:$PORT is listening..."

if nc -z -w 1 "$HOST" "$PORT" &>/dev/null; then
    echo "$HOST:$PORT is listening."
    exit 0
else
    echo "$HOST:$PORT is not listening."
    exit 1
fi

How it works: This script uses `netcat` (`nc`) to check if a specific TCP port on a given host is open and listening. The `-z` flag performs a zero-I/O scan, and `-w 1` sets a timeout of 1 second, making it a quick and efficient way to determine service availability.

Checking if a TCP Port is Listening for Service Availability

Need help integrating this into your project?