CURLOPT_POST (3) - Linux Manuals
CURLOPT_POST: request a HTTP POST
NAME
CURLOPT_POST - request a HTTP POSTSYNOPSIS
#include <curl/curl.h>CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POST, long post);
DESCRIPTION
A parameter set to 1 tells libcurl to do a regular HTTP post. This will also make the library use a "Content-Type: application/x-www-form-urlencoded" header. (This is by far the most commonly used POST method).Use one of CURLOPT_POSTFIELDS(3) or CURLOPT_COPYPOSTFIELDS(3) options to specify what data to post and CURLOPT_POSTFIELDSIZE(3) or CURLOPT_POSTFIELDSIZE_LARGE(3) to set the data size.
Optionally, you can provide data to POST using the CURLOPT_READFUNCTION(3) and CURLOPT_READDATA(3) options but then you must make sure to not set CURLOPT_POSTFIELDS(3) to anything but NULL. When providing data with a callback, you must transmit it using chunked transfer-encoding or you must set the size of the data with the CURLOPT_POSTFIELDSIZE(3) or CURLOPT_POSTFIELDSIZE_LARGE(3) options. To enable chunked encoding, you simply pass in the appropriate Transfer-Encoding header, see the post-callback.c example.
You can override the default POST Content-Type: header by setting your own with CURLOPT_HTTPHEADER(3).
Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with CURLOPT_HTTPHEADER(3) as usual.
If you use POST to a HTTP 1.1 server, you can send data without knowing the size before starting the POST if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER(3). With HTTP 1.0 or without chunked transfer, you must specify the size in the request.
When setting CURLOPT_POST(3) to 1, it will automatically set CURLOPT_NOBODY(3) to 0.
If you issue a POST request and then want to make a HEAD or GET using the same re-used handle, you must explicitly set the new request type using CURLOPT_NOBODY(3) or CURLOPT_HTTPGET(3) or similar.