curl parses my json object in –raw-data as its arguments

I’m trying to post data to an API using curl, I’m using this bash script:

script.sh

send_command () {
        echo "{\"cmd\":\"$@\"}" 
        curl --request POST \
                 --data-raw "{\"cmd\":\"$@\"}" \
                 -H "Content-Type: application/json"\
                 "http://localhost:8080/addCmd/" 
}

command_1 () {
        send_command test_command \
        -I {{files1}} \
        ---files1 'my_file.txt'\
}

after sourcing from script.sh then running command_1 in the terminal, I get this error:

{"cmd":"test_command -I {{files1}} ---files1 my_file.txt"}
curl: option ---files1: is unknown
curl: try 'curl --help' or 'curl --manual' for more information

I changed ---files1 to --files1 and it produces the same error.

>Solution :

"$@" expands to multiple words (see 2.5.2 Special Parameters of the POSIX shell language specification).

Consequently, --data-raw "{\"cmd\":\"$@\"}" expands to more than 2 tokens if you passed multiple parameters to your function. For instance, invoking send_command a 'b c' d will expand to the following tokens:

'--data-raw' '{"cmd":"a' 'b c' 'd"}'

Which means that 'b c' and 'd"}' will be parsed as distinct parameters to curl.

If you want all parameters to expand to a single word, use "$*":

curl --data-raw '{"cmd":"'"$*"'"}'

(or the equivalent --data-raw "{\"cmd\":\"$*\"}", depending on whether you prefer to escape nested quotes.)

But this will still break when one of your parameters contains a double quote, because the result will be invalid JSON.

If you need to generate/construct JSON, I recommend using jq:

jq -nc --arg cmd "$*" '{$cmd}' | curl --data-raw @-

or

curl --data-raw "$(jq -nc --arg cmd "$*" '{$cmd}')"

This does not suffer from the same limitations and will properly escape any embedded quotes in your input.

Or, if you have HTTPie available:

http :8080/addCmd/ cmd="$*"