Curl: one-liner to test http/2 support

Question

I'm currently writing an unit test to check if http/2 is supported.

Is there a curl one-liner which checks if http/2 is supported and outputs a response that is easy to parse?

Answer 1

HTTP/2 supported:

$ curl -sI https://curl.se -o/dev/null -w '%{http_version}\n'
2

HTTP/2 not supported (instead serving 1.1 in this case):

$ curl -sI http://curl.se -o/dev/null -w '%{http_version}\n'
1.1

(curl 7.50.0 or later is required for this command line to work)

Answer 2

Run

curl --version

and look for HTTP2 on the Features list

Answer 3

Here you can find a list of Tools for debugging, testing and using HTTP/2.

Probably the easiest one from the command line is:

$ is-http2 www.cloudflare.com

But that requires npm install -g is-http2-cli

For testing using curl you may need to compile it using the nghttp library, in macOS this can be done by using brew you could use:

$ brew install curl --with-nghttp2

And then you could use what @daniel-stenberg suggests in his answer

$ curl -sI https://curl.haxx.se -o/dev/null -w '%{http_version}\n'

In where you will get a 2 if http2 is supported.

Answer 4

I used

curl -kvso /dev/null --http2 https://app.domain.com:443

which returned

...
> GET / HTTP/2
...
< HTTP/2 302
...

this is not checking if HTTP2 is supported, but check if HTTP2 actually works.