Cron is one of those tools where the syntax looks obvious until a job fires at the wrong time and you start digging. Five behaviors below are documented in the man page and still catch people who've been writing cron for years. Each one is in a footnote most tutorials skip. Quick disclosure on this one: the cron builder I link to below is something I built. After enough years of writing 5-field expressions by hand, I wanted a tool that showed me the next 5 fire times in my actual local timezone before I committed. Free, client-side, no signup. Linking to it because it's the workflow I use now. I think most devs learn cron the same way. You copy something off Stack Overflow that looks close to what you want, you tweak a number, you commit it, and then a few days later something fires at the wrong time and you start reading the man page properly. The 5 behaviors below are the ones I see trip people up over and over. None are exotic. All are documented. All pass code review.…