Linux command line tool for uploading files over HTTP as multipart/form-data?

Use curl:

curl -F "file=@localfile;filename=nameinpost" url.com

It is possible to do this with wget only. At least with version 1.13.4 and maybe others. The --post-file option allows you to specify a file to send, so long as the postdata file is constructed properly.

I have also tested this with binary files and it works as expected. You do NOT need to base64 encode the file, but you do need to ensure your file does not contain the boundary.

The minimum command required to make this work would be:

wget --header="Content-type: multipart/form-data boundary=FILEUPLOAD" --post-file postfile http://domain/uploadform

and the postdata file would need to contain something like:

--FILEUPLOAD
Content-Disposition: form-data; name="comment"

I love uploading files!

--FILEUPLOAD
Content-Disposition: form-data; name="uploadFile"; filename="myfile.bin"; 
Content-Type: application/octet-stream
Media Type: application/octet-stream

Give me some automated file upload action!

--FILEUPLOAD--

A number of details are important here:

1. Lines in the post data file are terminated with \r\n. The only exception is data inside the file context.
2. Every BOUNDARY attribute in the postdata must match the BOUNDARY value in the call to wget. (FILEUPLOAD in the example)
3. All boundaries are prefixed with two hyphens "--" and terminated with \r\n
4. The last boundary is suffixed with two extra hyphens "--" and terminated with \r\n
5. Each piece of data, file content or parameter value, is surrounded by an empty line "\r\n"

I thought this might help someone since some controlled environments have wget but not curl.