Build a Zero-Dependency Terminal Reminder System (Cron + Shell)

As Linux users, we often rely on heavy tools for things that could be solved with a few lines of shell. In this tutorial, I’ll show you how I built a zero-dependency reminder system that lives entirely in the terminal.

No GUI. No background apps. No distractions. Just a clean, minimal workflow that reminds you of important tasks like system updates.

💡 The Idea

The concept is simple:

•Step 1: A cron job writes reminders to a file

•Step 2: Your shell displays that file on startup

•Step 3: You see reminders naturally when opening a terminal

This turns your shell into a passive notification system.

📁 Step 1: Create a Reminder File

We’ll store reminders in a simple file:

touch ~/.todo

This file will act as your lightweight task list.

⏰ Step 2: Add a Weekly Cron Job

Edit your crontab:

crontab -e

Add the following line:

0 9 * * 1 echo "$(date '+%Y-%m-%d %H:%M') - Run sudo pacman -Syu" >> /home/mosaid/.todo

•Explanation:

•0 9 * * 1: Every Monday at 09:00

•echo: Adds a timestamped reminder

•>>: Appends instead of overwriting

🖥️ Step 3: Display Reminders in Your Shell

Now we make the reminders visible when opening a terminal.

For Bash:

echo 'cat ~/.todo' >> ~/.bashrc

For Zsh:

echo 'cat ~/.todo' >> ~/.zshrc

Now every new terminal session will display your reminders automatically.

✨ Step 4: Make It Cleaner

Instead of dumping the entire file, show only recent entries:

tail -n 5 ~/.todo

Update your shell config:

echo 'echo "---- TODO ----"' >> ~/.bashrc
echo 'tail -n 5 ~/.todo' >> ~/.bashrc

🎨 Optional: Highlight Important Tasks

grep --color=always pacman ~/.todo

This makes update reminders stand out visually.

🧹 Optional: Clean Completed Tasks

Once you’ve updated your system, remove the reminder:

sed -i '/pacman -Syu/d' ~/.todo

You can also automate cleanup if needed.

🚀 Extending the System

This is where things get interesting. You can easily expand this idea:

•Backups: Weekly backup reminders

•Disk cleanup: Notify when to clean cache

•Security: Remind yourself to check logs

•Multiple machines: Sync .todo with git

You now have a fully customizable reminder system.

⚖️ Cron vs Systemd Timers

Cron is simple and works everywhere, but modern systems also support systemd timers.

•Cron: Easy, universal, quick setup

•Systemd timers: More robust, better logging, tighter integration

If you want a more advanced setup, consider migrating later.

🧠 Why This Works

This approach is powerful because:

•No dependencies: Uses only built-in tools

•Zero overhead: No background services

•Contextual: Appears exactly when you open a terminal

•Hackable: Fully customizable to your workflow

It embraces the Unix philosophy: do one thing well.

🏁 Conclusion

What started as a simple cron job becomes a flexible, minimal reminder system that integrates seamlessly into your daily workflow.

Sometimes, the best tools aren’t the most complex—they’re the ones you fully control.