Example for checking a port in bash

bash_check_port.sh

#!/bin/sh
# simple script to check if a port on a host is reachable

host=$1
port=$2

if [[ -z "$host" ]] || [[ -z "$port" ]];then
    echo "Usage: check_port <host> <port>"
    exit 1
fi

nc -z $host $port 2>&1 >/dev/null

if [ $? -ne 0 ];then
    echo "Port seems to be not reachable on host $host"
    exit 1
else
    echo "Successfully connected to port $port on host $host"
    exit 0
fi