diary:

Syntax:	diary ( )
	diary ( "filename" )

Description:

	The diary function writes a log of the current RLaB session
	(after the diary() function is invoked) to the file specified
	by the string argument or the default diary file `DIARY', if
	diary() is invoked without an argument.

	The diary file is opened in write mode. A string containing
	the date, and time are written when the file is opened.

	Invoking diary() a second time with no arguments will close
	the currently opened diary file.
