Cron Jobs in Five Minutes

Slide previews

1. 

   tips

   Stop Running Things Manually

   If you keep opening the terminal to run the same command on the same schedule, you are the cron job. It's time to fix that.

   swipe →
2. 02

   The Pain

   You Are Already The Cron Job

   Every morning. Every Friday. Every deploy. You SSH in, run the thing, close the window. Until you forget once, and now there's an incident.

   • Daily backup you keep meaning to script.
   • Cleanup that fails when you go on holiday.
   • Manual reports that should email themselves.

   
3. 03

   The Idea

   It's Just A Schedule + Command

   A cron job is one line. Five fields that say when, followed by the command. The whole thing is shorter than this body text.

   bash

   # Run every day at 6am
   0 6 * * *  /usr/local/bin/backup.sh
   
   # Run every Monday at 9am
   0 9 * * 1  npm run weekly-report

   
4. 04

   The Syntax

   Five Asterisks, Read Left To Right

   Minute, hour, day-of-month, month, day-of-week. Use a number, a list, or a star for any. That's the whole language.

   txt

   *  *  *  *  *  command
   |  |  |  |  |
   |  |  |  |  +-- day of week (0-6, Sun=0)
   |  |  |  +----- month (1-12)
   |  |  +-------- day of month (1-31)
   |  +----------- hour (0-23)
   +-------------- minute (0-59)

   
5. 05

   Where It Lives

   Pick The Wrapper That Fits

   The five asterisks haven't changed in decades. What changes is where you put them. Modern platforms hide the server entirely.

   • Linux: crontab -e on your VPS.
   • Vercel: vercel.json `crons` block.
   • GitHub Actions: schedule trigger on workflow.
   • App-level: node-cron, BullMQ, Sidekiq.

   
6. 06

   Gotchas

   Two Things That Will Bite

   Almost everyone trips on the same two issues the first time. Knowing them upfront saves an hour of confusion.

   • Timezone: most cron is UTC by default.
   • No retries: if it fails, it just fails.
   • Log everything. Cron runs silently.

   
7. 07

   Closing

   Five Asterisks. That's The Whole Wall.

   The syntax looked scary, so you ran things by hand. Five minutes of learning it pays back every week for the rest of your career.

   • If you do it twice, automate it.
   • Start with one daily job. Build from there.

   Tomorrow morning, something useful runs without you. Quietly. Reliably. Forever.

   

Slide 1 of 7