Bash – Proper escaping of double quotations for curl post data

bashcommand linecurlescape-charactersshell

I'm trying to test out a server, by sending it JSON data and reading the response.

I need to POST data like {"item":"value with spaces"} but when I use curl I find that it sends the backslashes as well as the double quotes:

curl -d "{\"item\":\"value with spaces\"}" http://myserver.com/somerubyapp?get=stuff

The server actually receives "{\"item\":\"value with spaces\"}" including the double quotes on the ends of the string, the backslashes, and everything.

Am I using curl incorrectly, or is it an issue with my shell, bash?

Best Answer

It's a kind of necroposting but I've had the same problem recently (with a different backend) and found that the reason is in a wrong Content-Type. By default it's "text/plain" or "text/html", and in my case curl -H "Content-Type: application/json" -d ... solved the issue.

Related Solutions

Posting XML through cURL using –data-binary

The & is interpreted by the shell you should use quotes (') around the URL:

curl --data-binary @/opt/somefile.xml 'http://1.2.3.4/gateway/submit?source=FOO&conversationid=1234567'

Buffer Command Output Completely Before Piping to Another Command

This is similar to a couple of the other answers. If you have the “moreutils” package, you should have the sponge command. Try

commandA | sponge | { IFS= read -r x; { printf "%s\n" "$x"; cat; } | commandB; }

The sponge command is basically a pass-through filter (like cat) except that it does not start writing the output until it has read the entire input. I.e., it “soaks up” the data, and then releases it when you squeeze it (like a sponge). So, to a certain extent, this is “cheating” – if there’s a non-trivial amount of data, sponge almost certainly uses a temporary file. But it’s invisible to you; you don’t have to worry about housekeeping things like choosing a unique filename and cleaning up afterwards.

The { IFS= read -r x; { printf "%s\n" "$x"; cat; } | commandB; } reads the first line of output from sponge. Remember, this doesn’t appear until commandA has finished. Then it fires up commandB, writes the first line to the pipe, and invokes cat to read the rest of the output and write it to the pipe.

Best Answer

Related Solutions

Posting XML through cURL using –data-binary

Buffer Command Output Completely Before Piping to Another Command

Related Question