# Launch options (/docs/reference/launch-options)

Command-line flags and environment variables accepted by the executable.

## Flags [#flags]

| Option                     | Effect                                                                    |
| -------------------------- | ------------------------------------------------------------------------- |
| `--x11`                    | Force the X11/XWayland overlay backend.                                   |
| `--update-offsets`         | Refresh live offsets and exit. `--refresh-offsets` is an alias.           |
| `--validate-config [path]` | Validate the supplied file, `CHUDCS2_CONFIG`, or `default.json` and exit. |

## Environment variables [#environment-variables]

| Variable                             | Effect                                                                 |
| ------------------------------------ | ---------------------------------------------------------------------- |
| `CHUDCS2_CONFIG`                     | Use a specific config file for startup.                                |
| `CHUDCS2_CONFIG_DIR`                 | Use a specific directory for profiles and `_settings.json`.            |
| `XDG_CONFIG_HOME`                    | Base directory for the user config fallback.                           |
| `DISPLAY`, `XAUTHORITY`              | X11 display authorization when the process is launched through `sudo`. |
| `WAYLAND_DISPLAY`, `XDG_RUNTIME_DIR` | Wayland display selection.                                             |

The former `CHUDCS2_SHM_NAME` and `CHUDCS2_SEM_NAME` variables are not read by the current executable. See [Packet layout](/docs/reference/shared-memory).