Sorry, I forgot to post an example:
# curl -v -F file=@test.tar.gz -T http:/mydomain.com
* About to connect() to mydomain.com port 80 (#0)
* Trying 192.168.15.1... connected
* Connected to mydomain.com (192.168.15.1) port 80 (#0)
> POST / HTTP/1.1
> User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> Host: mydomain.com
> Accept: */*
> Content-Length: 3337675
> Expect: 100-continue
> Content-Type: multipart/form-data; boundary=----------------------------a12017330dd6
>
< HTTP/1.1 100 Continue
< HTTP/1.1 413 Request Entity Too Large
< Server: nginx 1.7.8
< Date: Tue, 23 Dec 2014 19:14:32 GMT
< Content-Type: text/html
< Content-Length: 204
< Connection: keep-alive
<
<html>
<head><title>413 Request Entity Too Large</title></head>
<body bgcolor="white">
<center><h1>413 Request Entity Too Large</h1></center>
<hr><center>nginx 1.7.8</center>
</body>
</html>
* Connection #0 to host mydomain.com left intact
* Closing connection #0