How can i add break line in curl with json data? - bash

Question

I am using this bash script to post a new message to my rocket.chat instance.
#!/usr/bin/env bash
function usage {
programName=$0
echo "description: use this program to post messages to Rocket.chat channel"
echo "usage: $programName [-b \"message body\"] [-u \"rocket.chat url\"]"
echo " -b The message body"
echo " -u The rocket.chat hook url to post to"
exit 1
}
while getopts ":b:u:h" opt; do
case ${opt} in
u) rocketUrl="$OPTARG"
;;
b) msgBody="$OPTARG"
;;
h) usage
;;
\?) echo "Invalid option -$OPTARG" >&2
;;
esac
done
if [[ ! "${rocketUrl}" || ! "${msgBody}" ]]; then
echo "all arguments are required"
usage
fi
read -d '' payLoad << EOF
{"text": "${msgBody}"}
EOF
echo $payLoad
statusCode=$(curl \
--write-out %{http_code} \
--silent \
--output /dev/null \
-X POST \
-H 'Content-type: application/json' \
--data "${payLoad}" ${rocketUrl})
echo ${statusCode}
Everthings works fine, so i can send a new message like this
./postToRocket.sh -b "Hello from here" -u $RocketURL
But when i try to add a message with multiple lines like this
./postToRocket.sh -b "Hello from here\nThis is a new line" -u $RocketURL
it doesn't work. I get the following output:
{"text": "Hello from heren New Line"}
200
So what do i need to change, to use break line with these bash script. Any ideas?

Answer 1

First, the thing making the backslash in your \n disappear was the lack of the -r argument to read. Making it read -r -d '' payLoad will fix that. However, that's not a good solution: It requires your callers to pass strings already escaped for inclusion in JSON, instead of letting them pass any/every possible string.
To make valid JSON with an arbitrary string -- including one that can contain newline literals, quotes, backslashes, or other content that has to be escaped -- use jq:
payLoad=$(jq -n --arg msgBody "$msgBody" '{"text": $msgBody}')
...and then, after doing that, amend your calling convention:
./postToRocket.sh -b $'Hello from here\nThis is a new line' -u "$RocketURL"

Answer 2

I believe this has already been answered in SO here
Should work by adding the $ sign and using single quotes:
./postToRocket.sh -b $'Hello from here\nThis is a new line' -u $RocketURL