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They told me Android couldn’t automate—Termux Crontab proved them wrong.

Back when I first dove into the world of open source, I was sitting in a crowded university lab, wrestling with a stubborn script that refused to run at the same time every day.

My eyes darted between the clock on my phone and the blinking cursor on my terminal, and I realized that true freedom isn’t just about access to code—it’s about the power to bend technology to your will.

That night, I discovered Termux Crontab. In a few simple commands, I transformed my Android device into a fully automated, always-on assistant—no proprietary lock-in, no closed doors, just pure FOSS ingenuity.

In this guide, you’ll learn how to harness that same open-source spirit to schedule your very first cron job on Termux.

Let’s embrace the ethos of collaboration and control—read on and start automating your Android world today!

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Table of Contents

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• What is Cron?
• Basic Cron Syntax
• Demystifying Cron Syntax Fields
  • 5.2 Setting File Permissions & Locations
• Setting Up Cron in Termux
• Use Case Examples
• Wrapping Up Your First Termux Crontab Job

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What is Cron?

Cron is a time-based job scheduler in Unix-like operating systems. Users schedule jobs (commands or scripts) to run periodically at fixed times, dates, or intervals. It’s a powerful utility for automating maintenance and administration tasks.

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Basic Cron Syntax

The cron syntax is straightforward once you get the hang of it. A crontab file contains one job per line, with the following structure:

* * * * * command_to_execute
| | | | |
| | | | +-- Day of the week (0 - 7) (Sunday=0 or 7)
| | | +---- Month (1 - 12)
| | +------ Day of the month (1 - 31)
| +-------- Hour (0 - 23)
+---------- Minute (0 - 59)

Each asterisk (*) represents a time field and can be replaced with specific values to define when the command should run. For example, if you want a command to run every day at 2:30 AM, you would use:

30 2 * * * command_to_execute

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Demystifying Cron Syntax Fields

Cron schedules are defined by five fields—minute, hour, day of month, month, and day of week—separated by spaces. Each field accepts:

• A single value (e.g., 5 → “at :05”)
• A range (1-5 → “days 1 through 5”)
• A list (0,30 → “at :00 and :30”)
• A step (*/15 → “every 15 minutes”)

For example,

30 7 * * 1-5 my_script.sh

runs my_script.sh every weekday at 7:30 AM. Play with an online cron expression tester (search “cron expression tester”) to get instant feedback on your schedules.

5.2 Setting File Permissions & Locations

Your cron job must point to an executable script. To prepare:

Store your scripts under (create if missing).

~/scripts/

Make executable:

chmod +x ~/scripts/backup.sh

Absolute paths only: cron won’t respect your $PATH, so always call

/data/data/com.termux/files/home/scripts/backup.sh.

With correct permissions and explicit paths, Termux Crontab can reliably launch any script without “permission denied” errors.

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Setting Up Cron in Termux

1. Install Cron in Termux: If you haven’t already, you’ll need to install the cron package in Termux. You can do this with the following command:

pkg install cronie X

After installation, start the cron service:

crond

Create a Crontab File: To schedule tasks, you’ll need to edit your crontab file. You can create or edit your crontab by typing:

crontab -e 

This will open an editor where you can define your cron jobs.

0 5 * * * /path/to/script.sh 

Understanding Cron Syntax: Cron jobs follow a specific syntax:

* * * * * command/to/run 

Each asterisk represents a time unit (minute, hour, day of month, month, day of week). For example:
This runs script.sh every day at 5:00 AM.

Running a Bash Script Every 5 Minutes: If you want to run a script every 5 minutes, you can add the following line to your crontab:

*/5 * * * * /path/to/script.sh

Running a Script at a Specific Time: To run a script at a specific time, such as 2:30 PM every day:

30 14 * * * /path/to/script.sh

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Use Case Examples

Sync Files Automatically: Use rsync to sync directories between your Android device and a server every hour.

0 * * * * rsync -av /source/directory/ /destination/directory

Backup Important Files: Create a backup of critical files every night at midnight.

0 0 * * * tar -czf /backup/location/backup.tar.gz /important/files/

Check for Software Updates: Automatically check for and install package updates daily.

0 2 * * * pkg update && pkg upgrade -y

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Wrapping Up Your First Termux Crontab Job

By now, you’ve:

• Installed and configured Termux Crontab
• Written and tested a basic cron schedule
• Learned troubleshooting tips for common errors

You’re officially on the path from manual nudges to hands-off automation. Imagine what else you could schedule—backups, notifications, even your morning coffee order (okay, maybe not that last one).

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