The TemporaryFilename() command returns a string that can be used as the name of a temporary file.  At the time of the call to TemporaryFilename no such file exists on the file system.  This filename is of the form , where each  is replaced with a random character.

The TemporaryFilename(prefix) command returns a string of the form  where each  is replaced with a random character.

The filename returned TemporaryFilename() does not exist at the time of the call to TemporaryFilename.  However, it is possible that another process may create it between the call to TemporaryFilename and when the file is actually opened.

If no temporary file can be created, an exception is raised.