Run ngrok tcp connection in background and get the public url

ngrok_tcp.sh

#!/bin/sh

LOCAL_PORT=${1-10000}

echo "Starting ngrok in the background on TCP port [ $LOCAL_PORT ]"
nohup ngrok tcp ${LOCAL_PORT} &>/dev/null &

echo -n "Extracting ngrok public URL for TCP ."
NGROK_PUBLIC_URL=""
while [ -z "$NGROK_PUBLIC_URL" ]; do
  # Run 'curl' against ngrok API and extract public URL for TCP using 'sed'
  export NGROK_PUBLIC_URL=$(curl --silent --max-time 10 --connect-timeout 5 \
                            --show-error http://127.0.0.1:4040/api/tunnels | \
                            sed -nE 's/.*public_url":"tcp:..([^"]*).*/\1/p')
  sleep 1
  echo -n "."
done

echo
echo "NGROK_PUBLIC_URL => [ tcp://$NGROK_PUBLIC_URL ]"