Вам не нужно - заголовок "Content-Length: $ LENGTH" .
Посмотрите на примере Google:
http://code.google.com/apis/gdata/articles/using_cURL.html#creating-entries
curl --request POST --data-binary "@template_entry.xml" $URL
Обратите внимание, что запрос GET не поддерживает передачу данных.
Также помните, что POST-запрос имеет 2 разные схемы кодирования. Это первая форма:
$ nc -l -p 6666 &
$ curl --request POST --data-binary "@README" http://localhost:6666
POST / HTTP/1.1
User-Agent: curl/7.21.0 (x86_64-pc-linux-gnu) libcurl/7.21.0 OpenSSL/0.9.8o zlib/1.2.3.4 libidn/1.15 libssh2/1.2.6
Host: localhost:6666
Accept: */*
Content-Length: 9309
Content-Type: application/x-www-form-urlencoded
Expect: 100-continue
.. -*- mode: rst; coding: cp1251; fill-column: 80 -*-
.. rst2html.py README README.html
.. contents::
Вы, вероятно, запрашиваете это:
-F/--form name=content
(HTTP) This lets curl emulate a filled-in form in
which a user has pressed the submit button. This
causes curl to POST data using the Content- Type
multipart/form-data according to RFC2388. This
enables uploading of binary files etc. To force the
'content' part to be a file, prefix the file name
with an @ sign. To just get the content part from a
file, prefix the file name with the symbol . The
difference between @ and is then that @ makes a
file get attached in the post as a file upload,
while the makes a text field and just get the
contents for that text field from a file.