CustomLog
CustomLog file|pipe format|nickname
Server config, virtual host
The first argument is the filename to which log records should be
written. This is used exactly like the argument to
TransferLog; that is, it is either a full path,
relative to the current server root, or a pipe to a program.
The format argument specifies a format for each line of the log file.
The options available for the format are exactly the same as those
for the argument of the LogFormat directive. If
the format includes any spaces (which it will in almost all cases),
it should be enclosed in double quotes.
Instead of an actual format string, you can use a format nickname
defined with the LogFormat directive.