device_connection_string: "<ADD DEVICE CONNECTION STRING HERE>"

"HostName=PulseAzure-BetterTogetherDemo.azure-devices.net;DeviceId=ubuntu1804-ko-001;SharedAccessKey=xdWDu2gnzsfsdfdsfds="

sed -i "s/<ADD DEVICE CONNECTION STRING HERE>/$CSTRING/g" config.yaml
sed: -e expression #1, char 38: unterminated `s' command