The JSON must be inside of single quotes, or else the shell and curl think that it is all different command line arguments to be parsed.
curl -o -skd '{ "jsonrpc": "2.0", "method": "addAction", "params":{"action":{"id": "Syslog","name": "Syslog Action","isSystem": false,"type": "SendSyslogMessage","arguments": [{"key": "SyslogServerName","value": "10.41.155.233"},{"key": "SyslogServerUseTcp","value": "0"},{"key": "SyslogServerUseTls","value": "0"},{"key": "SyslogServerNoBsdCompat","value": "0"},{"key": "SyslogServerCaCertChain","value": ""},{"key": "SyslogServerAllowOffTimeRangeCerts","value": "0"},{"key": "SyslogServerPort","value": "514"}]}},"id": 1}'
2
solved Curl command execution in linux – globbing error [closed]