docs/libcurl/opts/CURLOPT_POST.3

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.TH CURLOPT_POST 3 "November 04, 2020" "libcurl 7.78.0" "curl_easy_setopt options"

.SH NAME
CURLOPT_POST \- request an HTTP POST
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POST, long post);
.SH 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 \fICURLOPT_POSTFIELDS(3)\fP or \fICURLOPT_COPYPOSTFIELDS(3)\fP
options to specify what data to post and \fICURLOPT_POSTFIELDSIZE(3)\fP or
\fICURLOPT_POSTFIELDSIZE_LARGE(3)\fP to set the data size.

Optionally, you can provide data to POST using the
\fICURLOPT_READFUNCTION(3)\fP and \fICURLOPT_READDATA(3)\fP options but then
you must make sure to not set \fICURLOPT_POSTFIELDS(3)\fP 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
\fICURLOPT_POSTFIELDSIZE(3)\fP or \fICURLOPT_POSTFIELDSIZE_LARGE(3)\fP
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 \fICURLOPT_HTTPHEADER(3)\fP.

Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header.
You can disable this header with \fICURLOPT_HTTPHEADER(3)\fP as usual.

If you use POST to an 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
\fICURLOPT_HTTPHEADER(3)\fP. With HTTP 1.0 or without chunked transfer, you
must specify the size in the request. (Since 7.66.0, libcurl will
automatically use chunked encoding for POSTs if the size is unknown.)

When setting \fICURLOPT_POST(3)\fP to 1, libcurl will automatically set
\fICURLOPT_NOBODY(3)\fP and \fICURLOPT_HTTPGET(3)\fP 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
\fICURLOPT_NOBODY(3)\fP or \fICURLOPT_HTTPGET(3)\fP or similar.
.SH DEFAULT
0, disabled
.SH PROTOCOLS
HTTP
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://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);
}
.fi
.SH AVAILABILITY
Along with HTTP
.SH RETURN VALUE
Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_POSTFIELDS "(3), " CURLOPT_HTTPPOST "(3), "