cURL: Read from File or Stdin

Redirect or pipe the content of a file or the output of another command as the input of cURL, for example, making a POST request with cURL.

This is done by prefixing the data parameter with @, the rest is the filename to read data from. With -, the data is coming from stdin:

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$ seq 17000 1 17001 | \
  curl \
    --request POST \
    --include \
    --header 'Content-Type: application/json' \
    --data-binary @- \
    --no-buffer \
    https://example.com/data

Command seq 17000 1 17001 returns:

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2
17000
17001

The size of the above two numbers is 12 bytes (including two newlines). But when reading data via @ with --data option, “carriage returns and newlines will be stripped out” [1]. If you check your server, you will see the content length is only 10 bytes.

To correct this problem, we will send the raw data using --data-binary option instead. This preserves \n and \r characters.