Getting only response header from HTTP POST using cURL

Question

One can request only the headers using HTTP HEAD, as option -I in curl(1).

$ curl -I /

Lengthy HTML response bodies are a pain to get in command-line, so I'd like to get only the header as feedback for my POST requests. However, HEAD and POST are two different methods.

How do I get cURL to display only response headers to a POST request?

Answer 1

-D, --dump-header <file>
       Write the protocol headers to the specified file.

       This  option  is handy to use when you want to store the headers
       that a HTTP site sends to you. Cookies from  the  headers  could
       then  be  read  in  a  second  curl  invocation by using the -b,
       --cookie option! The -c, --cookie-jar option is however a better
       way to store cookies.

and

-S, --show-error
       When used with -s, --silent, it makes curl show an error message if it fails.

and

-L/--location
      (HTTP/HTTPS) If the server reports that the requested page has moved to a different location (indicated with a Location: header and a 3XX response
      code), this option will make curl redo the request on the new place. If used together with -i/--include or -I/--head, headers from  all  requested
      pages  will  be  shown.  When authentication is used, curl only sends its credentials to the initial host. If a redirect takes curl to a different
      host, it won’t be able to intercept the user+password. See also --location-trusted on how to change this. You can limit the amount of redirects to
      follow by using the --max-redirs option.

      When curl follows a redirect and the request is not a plain GET (for example POST or PUT), it will do the following request with a GET if the HTTP
      response was 301, 302, or 303. If the response code was any other 3xx code, curl will re-send the following  request  using  the  same  unmodified
      method.

from the man page. so

curl -sSL -D - www.acooke.org -o /dev/null

follows redirects, dumps the headers to stdout and sends the data to /dev/null (that's a GET, not a POST, but you can do the same thing with a POST - just add whatever option you're already using for POSTing data)

note the - after the -D which indicates that the output "file" is stdout.

Answer 2

The other answers require the response body to be downloaded. But there's a way to make a POST request that will only fetch the header:

curl -s -I -X POST http://www.google.com

An -I by itself performs a HEAD request which can be overridden by -X POST to perform a POST (or any other) request and still only get the header data.

Answer 3

The Following command displays extra informations

curl -X POST http://httpbin.org/post -v > /dev/null

You can ask server to send just HEAD, instead of full response

curl -X HEAD -I http://httpbin.org/

Note: In some cases, server may send different headers for POST and HEAD. But in almost all cases headers are same.

Answer 4

For long response bodies (and various other similar situations), the solution I use is always to pipe to less, so

curl -i https://api.github.com/users | less

or

curl -s -D - https://api.github.com/users | less

will do the job.

Answer 5

Maybe it is little bit of an extreme, but I am using this super short version:

curl -svo. <URL>

Explanation:

-v print debug information (which does include headers)

-o. send web page data (which we want to ignore) to a certain file, . in this case, which is a directory and is an invalid destination and makes the output to be ignored.

-s no progress bar, no error information (otherwise you would see Warning: Failed to create the file .: Is a directory)

warning: result always fails (in terms of error code, if reachable or not). Do not use in, say, conditional statements in shell scripting...

Answer 6

Much easier – this is what I use to avoid Shortlink tracking – is the following:

curl -IL http://bit.ly/in-the-shadows

…which also follows links.

Answer 7

While the other answers have not worked for me in all situations, the best solution I could find (working with POST as well), taken from here:

curl -vs 'https://some-site.com' 1> /dev/null

Answer 8

headcurl.cmd (windows version)

curl -sSkv -o NUL %* 2>&1

• I don't want a progress bar -s,
• but I do want errors -S,
• not bothering about valid https certificates -k,
• getting high verbosity -v (this is about troubleshooting, is it?),
• no output (in a clean way).
• oh, and I want to forward stderr to stdout, so I can grep against the whole thing (since most or all output comes in stderr)
• %* means [pass on all parameters to this script] (well(https://stackoverflow.com/a/980372/444255), well usually that's just one parameter: the url you are testing

real-world example (on troubleshooting proxy issues):

C:\depot>headcurl google.ch | grep -i -e http -e cache

Hostname was NOT found in DNS cache
GET HTTP://google.ch/ HTTP/1.1
HTTP/1.1 301 Moved Permanently
Location: http://www.google.ch/
Cache-Control: public, max-age=2592000
X-Cache: HIT from company.somewhere.ch
X-Cache-Lookup: HIT from company.somewhere.ch:1234

---

Linux version

for your .bash_aliases / .bash_rc:

alias headcurl='curl -sSkv -o /dev/null $@  2>&1'