How to POST file contents using cURL?

Question

I want to do an HTTP POST of the contents (as a string) of a local file located at path/to/my-file.txt to a URL endpoint at http://example.com/.

For example, I might want to do the following:

Extract the contents of the file my-file.txt as a string.
URL encode the string.
Store the encoded string as a variable named foo.

Then do something like this:

curl -d "data=foo" http://example.com/

(I don't actually need the foo variable. It's just a convenient way to describe my question.)

What are the commands I would need to execute this? Do I need to write a shell script? If so, how might it look?

See https://stackoverflow.com/questions/5143915/test-file-upload-using-http-put-method — rogerdpack, Jan 22 '21 at 21:04

score 49 · Accepted Answer · edited Jun 07 '21 at 11:46

49

According to the last section of -d in man curl:

If you start the data with the letter @, the rest should be a file name to read the data from, or - if you want curl to read the data from stdin. Multiple files can also be specified. Posting data from a file named foobar would thus be done with --data @foobar. When --data is told to read from a file like that, carriage returns and newlines will be stripped out.

That is you don't have to do anything fancy just prepend your filename with a @.

edited Jun 07 '21 at 11:46

Lii

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answered Mar 19 '16 at 09:52

user556625

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And if you want some useful shell escaping (eg. to use jq to preprocess some JSON, try: ```curl ... -d @<(jq '{"schema": . | tostring }' myschema.avsc')``` Use-case: wrap a JSON document into a string of another JSON document to pass it to a REST API. (Confluent Schema Registry) – Cameron Kerr Jun 15 '18 at 00:14
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Also keep in mind that if you're uploading binary files, you should use `--data-binary`. – ahmet alp balkan Aug 07 '19 at 00:18
how can we post data from a url? – Jus12 Feb 19 '21 at 12:00
PLEASE How can I stop stripping line endings from the file input? I need it because of elasticsearch bulk format needs to ended with new line. – Čamo Jul 01 '21 at 14:27
@Čamo See the comment of Ahmet – gkephorus Nov 01 '21 at 11:39
I found it already. – Čamo Nov 01 '21 at 18:43

Pierz · Answer 2 · 2020-06-08T18:08:37.003

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As mentioned in this related question if you want the file uploaded without any changes (curl defaults to stripping carriage-return/line-feed characters) then you may want to use the --data-binary option:

curl -X POST --data-binary @path/to/my-file.txt http://example.com/

edited Jun 08 '20 at 18:08

answered May 07 '19 at 10:53

Pierz

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But I need to send application/json but with line endings – Čamo Jul 01 '21 at 14:28
I need it because of Elasticsearch _bulk api and the solution is to send header Content-Type: application/x-ndjson – Čamo Jul 01 '21 at 17:53

score 24 · Answer 3 · edited Aug 26 '20 at 05:43

24

To be explicitly clear, the accepted answer suggests:

curl -d "data=@path/to/my-file.txt" http://example.com/

The manual reference is here.

Also see this SE answer and this one also for multi-parts.

edited Aug 26 '20 at 05:43

Yonatan

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answered Mar 19 '16 at 10:38

Mowzer

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Not really. The way you state it can be confusing, and people might not know what you mean. The original question wanted to have `data=foo` sent to the server. The file called my-file.txt would contain only `data=foo`. Then the curl syntax would be `curl -X POST -d @path/to/my-file.txt http://example.com`. Your syntax is a bit non-standard and confusing. – Steve Storck Jul 17 '21 at 02:13
Does not upload the file for me. – Yuki Aug 04 '21 at 13:21

How to POST file contents using cURL?

3 Answers3