(HTTP) Tells curl to use HTTP version 1.0 instead of using its internally preferred: HTTP 1.1.
--http1.1
(HTTP) Tells curl to use HTTP version 1.1. This is the internal default version. (Added in 7.33.0)
--http2
(HTTP) Tells curl to issue its requests using HTTP 2. This requires that the underlying libcurl was built to support it. (Added in 7.33.0)
--http2-prior-knowledge
(HTTP) Tells curl to issue its non-TLS HTTP requests using HTTP/2 without HTTP/1.1 Upgrade. It requires prior knowledge that the server supports HTTP/2 straight away. HTTPS requests will still do HTTP/2 the standard way with negotiated protocol version in the TLS handshake.
HTTP/2 support in general also requires that the underlying libcurl was built to support it. (Added in 7.49.0)
How would someone set http version to 1.0?
https://curl.haxx.se/docs/manpage.html
-0, --http1.0
(HTTP) Tells curl to use HTTP version 1.0 instead of using its internally preferred: HTTP 1.1.
--http1.1
(HTTP) Tells curl to use HTTP version 1.1. This is the internal default version. (Added in 7.33.0)
--http2
(HTTP) Tells curl to issue its requests using HTTP 2. This requires that the underlying libcurl was built to support it. (Added in 7.33.0)
--http2-prior-knowledge
(HTTP) Tells curl to issue its non-TLS HTTP requests using HTTP/2 without HTTP/1.1 Upgrade. It requires prior knowledge that the server supports HTTP/2 straight away. HTTPS requests will still do HTTP/2 the standard way with negotiated protocol version in the TLS handshake.
HTTP/2 support in general also requires that the underlying libcurl was built to support it. (Added in 7.49.0)