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CURLOPT_POST

Section: curl_easy_setopt options (3)
Updated: May 05, 2017
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NAME

CURLOPT_POST - request a HTTP POST

SYNOPSIS

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.

DEFAULT

0, disabled

PROTOCOLS

HTTP

EXAMPLE

CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/foo.bin");
  curl_easy_setopt(curl, CURLOPT_POST, 1L);

  /* set up the read callback with CURLOPT_READFUNCTION */

  ret = curl_easy_perform(curl);

  curl_easy_cleanup(curl);
}

AVAILABILITY

Along with HTTP

RETURN VALUE

Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.