# NSPR_LOG_FILE

This environment variable specifies the file to which log messages are
directed.

## Syntax

```
filespec
```

*filespec* is a filename. The exact syntax is platform specific.

## Description

Use this environment variable to specify a log file other than the
default. If {ref}`NSPR_LOG_FILE` is not in the environment, then log output
is written to `stdout` or `stderr`, depending on the platform. Set
{ref}`NSPR_LOG_FILE` to the name of the log file you want to use. NSPR
logging, when enabled, writes to the file named in this environment
variable.

For MS Windows systems, you can set {ref}`NSPR_LOG_FILE` to the special
(case-sensitive) value `WinDebug`. This value causes logging output to
be written using the Windows function `OutputDebugString()`, which
writes to the debugger window.