Difference between "curl -XPUT --data-binary @${file_path}" and "curl -XPUT -T ${file_path}"?

Question

While using curl to POST or PUT a file to a url, there are two different ways to load the file content:

1. -T ${file_path}
2. --data-binary @${file_path} or -d $@{file_path} (for ascii data files)

What is the difference between these two options?

Answer 1

To understand differences between these options, you can either read the man page or make some experiments.

The man page

-d, --data

Sends the specified data in a POST request to the HTTP server, in the same way that a browser does when a user has filled in an HTML form and presses the submit button. This will cause curl to pass the data to the server using the content-type application/x-www-form-urlencoded. [...]

-T, --upload-file

This transfers the specified local file to the remote URL. [...] If this is used on an HTTP(S) server, the PUT command will be used. [...]

Make some experiments

Run netcat in listening mode (macOS version):

nc -l localhost 8989 

Create a test file:

echo test>test 

Run the curl commands and check the results on the listening side:

% curl -d "name=test" localhost:8989 POST / HTTP/1.1 Host: localhost:8989 User-Agent: curl/7.84.0 Accept: */* Content-Length: 9 Content-Type: application/x-www-form-urlencoded name=test % curl -T test localhost:8989 PUT /test HTTP/1.1 Host: localhost:8989 User-Agent: curl/7.84.0 Accept: */* Content-Length: 5 Expect: 100-continue test 

To answer your question, the -d option make a POST request by sending the data with the x-www-form-urlencoded format, and -T send a PUT request without formatting the data.