Starts logging to the given file. Everything output by the mud will be saved. If timeformat is specified, it is considered a string to be passed to the C strftime() function, with special tags that are replace with the current time and/or date, and the resulting string is prefixed to each line. (See the strftime manual page for the possible tags.) If this argument is not given, nothing is prefixed to the lines.

It is not possible to log to more than one file at one time, if there is already a log file open, it will be closed and logging will continue to the new file.

With no arguments, this function stops logging output.