Run A Shell Script Daily with Cron.

To run a shell script daily using crontab on Linux , follow these steps:

1. Create a new shell script: Write your desired commands in a new file with a .sh extension, e.g., daily_script.sh. Make sure the script has execute permissions by running chmod +x daily_script.sh.
2. Open crontab: As the root user, open the crontab file using sudo crontab -e. This will launch your default text editor.
3. Add a new cron job: In the crontab file, add a new line with the following format:

   minute hour day month day_of_week command
   

   For a daily run at midnight, use:

   0 0 * * * /path/to/daily_script.sh
   

   Replace /path/to/daily_script.sh with the actual path to your script file.

Here's a breakdown of the fields:

• minute: 0 (runs at the beginning of the minute)
• hour: 0 (midnight)
• day: * (any day of the month)
• month: * (any month)
• day_of_week: * (any day of the week)

• command: the path to your shell script

• Save and exit: Save the changes to the crontab file and exit the editor.

• Verify the cron job: Check the cron logs (usually /var/log/cron or /var/log/syslog) to ensure the job is running correctly.

Tips:

• Make sure the script has execute permissions (chmod +x) and is located in a directory accessible by the cron daemon.
• If your script requires specific environment variables or dependencies, ensure they are set up correctly.
• You can add multiple cron jobs by adding new lines to the crontab file.
• To disable email output for a specific cron job, add >/dev/null 2>&1 at the end of the command line.

Example crontab entry:

0 0 * * * /home/user/daily_script.sh > /dev/null 2>&1

This will run the daily_script.sh script at midnight every day, and redirect any output to /dev/null to suppress email notifications.