the Unix date command: yesterday, tomorrow, nanoseconds

• date (Unix) - Wikipedia, the free encyclopedia
• https://www.gnu.org/software/coreutils/manual/html_node/date-invocation.html – the GNU date root manual page

GNU's date lets you specify yesterday, tomorrow, Sunday, … to be displayed following the format specification you supply. And (if available) you can also get nanoseconds displayed. Please do not complain, that precisions between nanoseconds and seconds are missing!

Maybe on your UNIX flavor computer GNU date is installed as gnudate or gdate (just like: gnutar, gtar, …).