Using curl for multipart/form-data with a file upload

Question

I have a server API that I have developed against the format used by Fiddler to do HTTP posts of files, which is a multipart/form-data post. I'm trying to get curl to do something similar (so I can stop using Fiddler for testing and instead have a separate program call out to curl programmatically).

Here is how it's set up in Fiddler, which is what I need to replicate. The file being uploaded is myfile.html file:

---------------------------acebdf13572468
Content-Disposition: form-data; name="fieldNameHere"; filename="myfile.html"
Content-Type: text/html

<@INCLUDE *C:\myfiles\myfile.html*@>
---------------------------acebdf13572468--

I need for curl to produce something similar: in particular the name= part, followed by the file content at the bottom of this part. I've tried this with:

curl -F "fieldNameHere=myfile.html" http://myapi.com/

When I do that, it seems to totally ignore my file though. Here's the verbose output if I add -v:

POST / HTTP/1.1
User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.27.1 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
Host: perl-h4.factset.io
Accept: */*
Content-Length: 166
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------981301fdaeb3

There isn't any file content at all (it's a large HTML file). So I think there might be something fundamental I'm missing here. Any pointers would be quite welcome.

Also, I have checked other Stack Overflow questions, like this: What is the right way to POST multipart/form-data using curl?

But they are basically saying to do something like what I'm doing here. So maybe the problem is not my syntax, but some other reason it doesn't want to read the file.

Peter Mortensen · Accepted Answer · 2025-07-03 18:01:54Z

25

Use:

curl -X POST  -F [email protected]  http://myapi.com/

or

-X POST is implied by -F (per comment), and quotes are optional

curl -F "[email protected]"  http://myapi.com/

edited Jul 3 at 18:01

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Oct 26, 2017 at 17:42

Scriptonomy

4,0551 gold badge18 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Daniel Stenberg Over a year ago

but no bonus points with the superfluous -X POST present there... =)

Stephen Over a year ago

Oh wow, so the problem is just that I was missing an @ sign. Amazing... thanks. I guess that tells curl that this is the name of an actual file?

Scriptonomy Over a year ago

Yes pretty much.

Peter Mortensen · Accepted Answer · 2025-07-03 18:09:11Z

11

For more complex requests:

curl
 -X POST "YOUR_API_URL"
 -H "Authorization: Bearer YOUR_TOKEN"
 -H "Accept: application/json"
 -H "Content-Type: multipart/form-data"
 -F "meta={\"YOUR_ATTRIBUTE\": \"YOUR_DATA\"};type=application/json"
 -F "text=PATH_TO_FILE;type=text/plain"

You can set several chunks together into one request. For more, check out Add blobs to objects in Azure Digital Twins!

edited Jul 3 at 18:09

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Jan 14, 2019 at 18:48

Adam Gerard

7462 gold badges9 silver badges24 bronze badges

Collectives™ on Stack Overflow

Using curl for multipart/form-data with a file upload

2 Answers 2

3 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related