The LogFile property is used to specify the name of a file
that will contain a log of all client activity. The LogFormat
and LogLevel properties affect the specific format for the file
and the level of detail included in the log. It is recommended that
you specify an absolute path to the log file, otherwise the path will
be relative to the current working directory. You may include
environment variables in the path surrounded by percent (%) symbols
and they will be expanded.
If the log file does not exist it will be created when the server
is started. If file already exists, the server will append the new
logging data to the file. The server must have permission to create
and/or modify the specified file.
Setting this property to an empty string after the server has been
started will have the effect of disabling logging, setting the logging
level to 0 and the logging format to ftpLogNone.