When Houdini quits from the command line, it may exit with one of the following codes:
| 0 | No error. |
| 1 | Generic error (catch-all code). |
| 2 | Misuse of shell built-ins (according to Bash documentation) |
| 3 | Failure to check out or verify an appropriate product license. |
| 4 | Socket communication failure. |
| 5 | Error while parsing UI definition file (.ui). |