downtimed is a program that monitors operating system downtime, uptime, shutdowns, and crashes and records such events. At OS startup it logs information about previous downtime. It then periodically updates a time stamp file on the disk, which is used to determine the approximate time when the system was last up and running. During a graceful system shutdown, it records a time stamp in another file. The downtimes(1) command line tool can be used to inspect records of past downtime.