GNU parallel is a shell tool for executing jobs in parallel locally or using remote computers. A job is typically a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. If you use xargs today you will find GNU parallel very easy to use, as GNU parallel is written to have the same options as xargs. If you write loops in shell, you will find GNU parallel may be able to replace most of the loops and make them run faster by running several jobs in parallel. GNU parallel makes sure output from the commands is the same output as you would get had you run the commands sequentially. This makes it possible to use output from GNU parallel as input for other programs.
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.