---
title: "Logging Settings"
description: "Logging settings of LumiScan VGR (from v2.0.0) - log directory, size, number and age of log files, and log levels for the console and each logger."
product: "LumiScan VGR"
component: "lumiscan-vgr"
version: "1.8.4"
display_version: "1.8.4.8"
latest_version: true
language: "en"
url: "https://docs.hdvisionsystems.com/en/lumiscan-vgr/json-settings/logging.html"
---

# Logging Settings – LumiScan VGR

*From v2.0.0.*

The optional `logging` section of the settings file sets the log directory, the size, number and age of the log files, and the log level of the console and of each logger. A key that is absent keeps the LumiScan VGR default, so `"logging": {"level": "DEBUG"}` changes only the level. The schema of the section is `logging.schema.json`.

```json
"logging": {
    "logDir": "",
    "level": "INFO",
    "flushLevel": "INFO",
    "duplicateFilterSeconds": 600,
    "console": { "enabled": true, "stream": "STDOUT" },
    "file": { "enabled": true, "dailyDirectories": true, "maxFileSizeMb": 5, "maxFiles": -1, "retentionDays": 30 },
    "loggers": {
        "ProcessResult": { "level": "DEBUG", "file": { "maxFiles": 5, "retentionDays": 15 } }
    }
}
```

| Key | Meaning |
| --- | --- |
| `logDir` | The top-level folder of all log files. Empty: `<HDVAppData>\LumiScan VGR\logs` (see [Generated Data and Files](https://docs.hdvisionsystems.com/en/lumiscan-vgr/output-data.html)). |
| `level`, `flushLevel` | `TRACE`, `DEBUG`, `INFO`, `WARN`, `ERROR`, `CRITICAL` or `OFF`. Messages of the flush level or above are written to the file at once. |
| `duplicateFilterSeconds` | Identical messages in a row are dropped for this many seconds; `0` switches the filter off. |
| `console` | `enabled`, and `stream` (`STDOUT` or `STDERR`). |
| `file.dailyDirectories` | `true`: a new subfolder every day, `<logDir>\<YYYY-MM-DD>\<logger>.log`. `false`: one rotating file per logger, `<logDir>\<logger>.log`. |
| `file.maxFileSizeMb`, `file.maxFiles` | The size at which a file is rotated, and the number of files kept per logger (per day with `dailyDirectories`); `-1` for any number. |
| `file.retentionDays` | Logs older than this many days are deleted. `0` keeps everything. |
| `loggers` | Settings of single loggers by name: `LumiScanVGR` (main log), `ProcedureCallLogger`, `ProcessResult` and `Deprecated`. |

> [!IMPORTANT]
> Every folder named `YYYY-MM-DD` in `logDir` counts as a log day and is deleted when it is older than `retentionDays`. Do not use the folder for other data.

## Overriding the Settings File

The same keys can be set by the user in `%LOCALAPPDATA%\HD Vision Systems GmbH\LumiScan VGR\logging.json` and, for one run, by environment variables. These override the settings file, in this order (highest first):

1. `HDV_LOG_LEVEL` and `HDV_LOG_FLUSH_LEVEL`: the level and the flush level of all loggers.
2. `HDV_LOG_LEVELS` (for example `ProcessResult=trace,Deprecated=warn`) and `<LOGGER>_LOG_LEVEL`: single loggers. `HDV_LOG_DIR` sets the folder.
3. The user file `logging.json`, or the file named by `HDV_LOG_CONFIG`.
4. The `logging` section of the settings file, then the LumiScan VGR defaults.

The settings are read when LumiScan VGR starts; a change takes effect after a restart. The first lines of a start, before the settings file is read, are written with the defaults.

> [!NOTE]
> The loggers of LumiScan VGR are also used by the camera library and the camera plugins, so their messages follow these settings and are in the same log files. Only the `LumiScanAPI` log, which the LumiScan API keeps for itself in `<HDVAppData>\LumiScanAPI\logs`, ignores them.