Start ngrok connection in background in fish shell with "source start_ngrok.sh".

start_ngrok.sh

#!/bin/sh

set NGROK_PUBLIC_URL ""

echo "Start ssh-access ngrok in background"
nohup ngrok start ssh-access &>/dev/null &

echo -e "Extracting ngrok port..."
while [ -z "$NGROK_PUBLIC_URL" ];
  sleep 1
  # Run 'curl' against ngrok API and extract public (using 'sed' command)
  set NGROK_PUBLIC_URL $(curl --silent --max-time 10 --connect-timeout 5 \
                            --show-error http://127.0.0.1:4040/api/tunnels | \
                            sed -nE 's/.*ngrok.i..([^"]*).*/\1/p')
end

echo "ngrok port => $NGROK_PUBLIC_URL"