Exit codes

Code	Meaning
0	Success
1	API error (4xx or 5xx response)
2	Authentication error
3	Validation error, including an invalid command line (unknown command or flag, missing argument)
4	Schema error
5	Internal error

API, authentication and validation errors come out as a JSON object {"error": {"code": …, "message": …}}. A command line that makes no sense (unknown command or flag) comes out as text, on stderr, with code 3.

if ! kobana billing invoices get "$ID" > fatura.json; then
  case $? in
    1) echo "The API rejected the request" ;;
    2) echo "Sign in again: kobana billing auth login" ;;
    3) echo "Invalid command or argument" ;;
  esac
fi