Curl post data and headers only

Question

I want to get the headers only from a curl request

curl -I www.google.com

All grand. Now I want to do that but to pass in post data too:

curl -I -d'test=test' www.google.com

But all I get is:

Warning: You can only select one HTTP request!

Anyone have any idea how to do this or am I doing something stupid?

Answer 1

The -I option tells curl to do a HEAD request while the -d'test=test' option tells curl to do a POST, so you're telling curl to do two different request types.

curl -s -d'test=test' -D- -o/dev/null www.google.com  

or, on Windows:

curl -s -d'test=test' -D- -onul: www.google.com  

That is the neatest way to do this as far as I can find. The options are:

• -D- Dump the header to the file listed, or stdout when - is passed, like this.
• -o/dev/null Send the body to the file listed. Here, we discard the body so we only see the headers.
• -s Silent (no progress bar)

Answer 2

-d means you are sending form data, via the POST method. -I means you are just peeking at the metadata via HEAD.

I'd suggest either

• Download to /dev/null and write the headers via the -D headerfile to the file headerfile
• Use -i to include the headers in the answers and skip everything from the first empty line.