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# os_log_debug

Sends a debug-level message to the logging system.

```
#define os_log_debug(log, format, ...)
```

## Parameters

`log`

The [`OS_LOG_DEFAULT`](/documentation/os/OS_LOG_DEFAULT) constant or a custom log object previously created by the [`os_log_create`](/documentation/os/os_log_create) function.

`format`

A constant string or format string that produces a human-readable log message. See [String Format Specifiers](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFStrings/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265).

## Discussion

Calling this function is equivalent to calling the `os_log_with_type` function and specifying a log type of <doc://com.apple.documentation/documentation/kernel/os_log_type_t/os_log_type_debug>.

## See Also

  <doc://com.apple.documentation/documentation/kernel/os_log_type_t/os_log_type_debug>


---

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