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How to Automate System Updates Using Bash Scripts

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Automating system updates using Bash scripts and RHEL's yum or dnf package manager ensures your Red Hat Enterprise Linux (RHEL)-based systems remain secure and up-to-date. Below is a guide tailored for RHEL environments.

Steps for Automating System Updates

  1. Create a Bash Script for Updates The script will:
    • Update the package repository.
    • Upgrade installed packages.
    • Remove unused packages (optional).
    • Log the results for review.

Example Script:

#!/bin/bash

# Variables
LOG_FILE="/var/log/system_update.log"
DATE=$(date '+%Y-%m-%d %H:%M:%S')

# Update and upgrade
echo "[$DATE] Starting system update..." | tee -a $LOG_FILE

# Update package list and upgrade packages
if sudo dnf update -y; then
    echo "[$DATE] System update successful." | tee -a $LOG_FILE
else
    echo "[$DATE] System update failed." | tee -a $LOG_FILE
    exit 1
fi

# Clean up unused packages
if sudo dnf autoremove -y && sudo dnf clean all; then
    echo "[$DATE] Cleanup successful." | tee -a $LOG_FILE
else
    echo "[$DATE] Cleanup failed." | tee -a $LOG_FILE
fi

echo "[$DATE] Update process completed." | tee -a $LOG_FILE
exit 0

Replace dnf with yum if using an older RHEL version.

  1. Make the Script Executable Save the script as update_system.sh and make it executable.
chmod +x update_system.sh
  1. Test the Script Run the script manually to confirm it works.
./update_system.sh
  1. Schedule the Script Using cron Automate execution by scheduling the script with cron.
  • Open the crontab editor:
crontab -e

  • Add a line to schedule the script. For example:

    • Run daily at 2:00 AM:
    0 2 * * * /path/to/update_system.sh
    • Run weekly at 3:00 AM on Sundays:
    0 3 * * 0 /path/to/update_system.sh

  • Save and exit.

  1. Verify the Cron Job Check the scheduled cron job.
crontab -l
  1. Monitor Logs Review logs for successful updates or troubleshoot errors. The script logs updates to /var/log/system_update.log.

Advanced Automation Enhancements

  1. Email Notifications Configure the script to send email alerts upon success or failure.

Example (Add to Script):

if sudo dnf update -y; then
    echo "System update completed successfully." | mail -s "System Update Success" admin@example.com
else
    echo "System update failed!" | mail -s "System Update Failure" admin@example.com
fi
  1. Exclude Certain Packages Avoid updating specific packages by marking them as held.
sudo dnf mark exclude <package-name>
  1. Automate Kernel Updates Separately Automate kernel updates only when needed to avoid unnecessary reboots.

By combining Bash scripting with RHEL-specific tools like dnf-automatic, you can fully automate system updates, enhance security, and reduce administrative overhead.

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