-v, --verbose Print debug information such as reception/transmission of frames and name/value pairs. -n, --null-out Discard download data. -s, --stat Print statistics. --no-tls Disable SSL/TLS. --no-connection-flow-control Disables connection level flow control. --no-stream-flow-control Disables stream level flow control. --upgrade Perform HTTP Upgrade for HTTP/2.0. This option is ignored if --no