Q. a number of systems automatically delete all user files when a user logs off or a job terminates unless the user explicitly requests that they be kept other systems keep all files unless the user explicitly deletes them.

converse the relative merits of each approach.

Answer: Deleting every files not specifically saved by the user has the advantage of minimizing the file space needed for each user by not saving unwanted or unnecessary files. Saving all files unless purposely deleted is more secure for the user in that it is not possible to lose files inadvertently by forgetting to save them.