Echo curl request header & body without sending it

Question

With the curl command line tool, is it possible to echo, print, or view the request, and not send it? Sort of like a -n option? I would like to see the request header & body, and anything else that's included. Is there anything else that's sent besides header & body?

Answer 1

A HTTP request is constructed with a request line, headers and a body.

curl does not seem to have a flag to do a "dry-run". Depending on your needs, you might be able to see what you want using netcat as a proxy:

$ nc -l localhost 8000 &
[1] 3150
$ curl --proxy localhost:8000 --silent --max-time 1 http://www.stackoverflow.com
GET http://www.stackoverflow.com HTTP/1.1
User-Agent: curl/7.19.7 (x86_64-pc-linux-gnu) libcurl/7.19.7 OpenSSL/0.9.8k zlib/1.2.3.3 libidn/1.15
Host: www.stackoverflow.com
Accept: */*
Proxy-Connection: Keep-Alive

[1]+  Done                    nc -l localhost 8000

Answer 2

Let me second the suggestion to use 'nc' (netcat) to get to see all the details without sending anything offsite to anywhere.

But you can also get all the details for any curl command line request by using the --trace or --trace-ascii commands that can dump all incoming and outgoing data and requests for inspection.

These options have the additional benefit in comparison to 'nc' that they can show the protocol details even for HTTPS operations and with "real" command lines etc.