How to send line break with curl?

Question

I've tried the following to send a line break with curl, but \n is not interpreted by curl.

curl -X PUT -d "my message\n" http://localhost:8000/hello

How can I send a line break with curl?

Answer 1

Sometimes you want to provide the data to be sent verbatim.

The --data-binary option does that.

Answer 2

Your shell is passing \ followed by n rather than a newline to curl rather than "my message\n". Bash has support for another string syntax that supports escape sequences like \n and \t. To use it, start the string with $' and end the string with ':

curl -X PUT -d $'my message\n' http://localhost:8000/hello

See ANSI-C Quoting in the Bash Reference Manual

Answer 3

There's a much easier way!

curl -X PUT -d $'my message\n' http://localhost:8000/hello

This will use ANSI-C Quoting to insert the newline character.

No piping, no data files. See also Sending Newlines with cURL.

Answer 4

The solution for someone who doesn't want to use files, and doesn't want to resort to shell escaping magic is:

curl -X POST --data-binary @- http://url.com <<EOF
line one
line two
EOF

But this is literal newlines in the post data payload, and not in form fields.

Answer 5

Had similar issue. While uploading a CSV file from Mac to cloud storage, new lines were being removed. After downloading it, the entire file looked like a single line. I tried adding different EOL characters \n \r \r\n with no success. Using --data-binary instead of -d solved the issue.

Btw this issue occurred only from Mac. -d worked just fine while making the call from CentOS machine. This very much looks like due to Mac's newline character. But don't feel like debugging any more.

Thanks a lot for your help.

curl -X PUT -d @filename.csv https://cloudstorage -H "content-type: text/csv"

vs

curl -X PUT --data-binary @filename.csv https://cloudstorage -H "content-type: text/csv"

Answer 6

(I ended up here with a slightly different question, so I'm just going to post my answer because it might help future explorers)

My solution applies to people who are sending form-style data, i.e. key/value pairs in a query string. Use the encoded line break, which is %0A, just like how an encoded space is %20. You can use http://meyerweb.com/eric/tools/dencoder/ to convert other symbols.

So if you want to set the key message to the value:

line one
another

you would send

curl --data "message=line%20one%0Aanother" http://localhost:8000/hello

Answer 7

A very easy way, just Shift-Enter in the console for the break. Very readable typing it in too.

curl -d "line1
line2" http-echo.com

Server gets this: line1\nline2

Do this to remove the line break:

curl -d "line1 \
line2" http-echo.com

Server gets this: line1 line2

Answer 8

Not an answer to your question, but I would work around it by creating a temporary file containing the message and line break, and give curl that file to work on:

curl -X PUT -d @message.txt http://localhost:8000/hello

From the manual:

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. The contents of the file must already be URL-encoded. Multiple files can also be specified. Posting data from a file named 'foobar' would thus be done with --data @foobar.

Answer 9

I was using Sendgrid with this code (copied below) originally found here https://sendgrid.com/docs/API_Reference/Web_API_v3/index.html

\n\n worked in Gmail, but \n was ignored. I tried to double the escape and other suggestions. I also tried \r\n and that did not work in Gmail either. Note: I didn't bother to test other email clients, maybe it was a Gmail-specific problem.

    curl --request POST \
  --url https://api.sendgrid.com/v3/mail/send \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{"personalizations": [{"to": [{"email": "your.email@example.com"}]}],"from": {"email": "example@example.com"},"subject": "Hello, World!","content": [{"type": "text/plain", "value": "Heya!"}]}'

Eventually I gave up looking for a solution and switched the text/plain to text/html and just used <br /> tags.

Someone suggested that Sendgrid converts plaintext to HTML if you have a tracking pixel enabled, which makes sense. Maybe the newlines were destroyed in the plaintext-to-html conversion process. I assume the client wants a tracking pixel, so decided to switch to HTML.