cron

https://man7.org/linux/man-pages/man5/crontab.5.html

1. 01intermediatecrondocker

   Reclaim disk space from Docker every Sunday

   A weekly cron line prunes Docker images, containers, networks and build cache untouched for seven days, and deliberately leaves volumes alone so data survives.

2. 02beginnercronbashcurlslack

   Tell a chat channel when a site goes down, once

   A five minute cron check posts to a chat webhook only when a site changes state, so an outage announces itself once and the recovery announces itself once.

3. 03beginnercronbashtar

   Back up one folder every night and keep two weeks

   A nightly cron job archives one folder to a dated tar.gz and deletes archives older than fourteen days, so a restore is always a single file away.