Command line curl can display response header by using -D
option, but I want to see what request header it is sending. How can I do that?
If you want more alternatives, You can try installing a Modern command line HTTP client like httpie which is available for most of the Operating Systems with package managers like brew, apt-get, pip, yum etc
eg:- For OSX
brew install httpie
Then you can use it on command line with various options
http GET https://www.google.com