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+# setup-auto-updates.sh
+
+A cross-compatible shell script for enabling unattended automatic updates on Debian and Ubuntu systems.  
+Designed for clean, predictable configuration using modern `Origins-Pattern` syntax.  
+Includes dry-run validation and systemd timer setup when supported.
+
+---
+
+**Version:** 2025-07-28  
+**License:** MIT
+
+---
+
+## Features
+
+- Detects Debian or Ubuntu and applies best-practice configuration
+- Configures `unattended-upgrades` to install regular and security updates automatically
+- Clears legacy `Allowed-Origins` and uses clean `Origins-Pattern` format
+- Supports both traditional and deb822-style APT sources
+- Enables systemd timers (`apt-daily.timer` and `apt-daily-upgrade.timer`) when available
+- Configures daily update checks, weekly autoclean, and auto-reboot at 4:00 AM if needed
+- Includes a dry-run validation with basic error detection
+- Prompts to delete the script after successful execution
+
+## Compatibility
+
+- **Debian**: Bookworm, Trixie, and newer
+- **Ubuntu**: Noble (24.04 LTS) and newer
+- Should be safe on any modern system with `unattended-upgrades` and `apt`
+
+## What It Does
+
+- Installs `unattended-upgrades` if missing
+- Writes a new `/etc/apt/apt.conf.d/50unattended-upgrades` using a robust and portable structure
+- Enables APT periodic updates via `/etc/apt/apt.conf.d/20auto-upgrades`
+- Enables systemd timers if `systemctl` is available
+- Does **not** run any updates itself or reboot your system directly
+
+## Example Output
+
+```
+[INFO] Unattended-upgrades configurator (Debian/Ubuntu)
+[INFO] Detected OS: Debian GNU/Linux 12 (bookworm)
+[INFO] Updating APT cache…
+[INFO] Installing unattended-upgrades…
+[INFO] Validating unattended-upgrades with a dry run…
+Allowed origins are: origin=Debian,archive=bookworm, origin=Debian,archive=bookworm-updates, ...
+[INFO] Timers:
+Mon 2025-07-28 06:40:14 MDT ... apt-daily-upgrade.timer
+Mon 2025-07-28 10:51:12 MDT ... apt-daily.timer
+[OK] Unattended updates configured. Regular + security updates will apply automatically; reboot at 04:00 if needed.
+```
+
+## Usage
+
+```bash
+sudo ./setup-auto-updates.sh
+```
+
+- Must be run as root
+- Prompts to delete itself after successful configuration if run interactively
+
+## Customization
+
+To change the default reboot time:
+
+```bash
+sudo REBOOT_TIME="03:30" ./setup-auto-updates.sh
+```
+
+To run without dry-run validation (not recommended), you can comment out or modify the `validate_with_dryrun()` function.
+
+## Notes
+
+- If APT is locked by another process, the script waits up to 3 minutes before proceeding
+- Dry-run validation logs are saved to `/tmp/unattended-upgrades-dryrun.*`
+- The script confirms presence of `systemctl` before enabling timers
+- Automatically overwrites existing configuration files with no backup:
+  - `/etc/apt/apt.conf.d/50unattended-upgrades`
+  - `/etc/apt/apt.conf.d/20auto-upgrades`
+
+## Self-Delete Behavior
+
+At the end of the script, a prompt asks if you'd like to remove the `.sh` file that was just executed.  
+This helps keep systems tidy after one-time provisioning.
+
+## Limitations
+
+- Does not configure granular package exclusions or holds
+- Will not trigger updates or reboots itself; configuration only
+- Does not install `powermgmt-base`, so power-check warnings may appear on laptops
+- Not compatible with non-Debian distributions (e.g., Fedora, Arch)
+
+## License
+
+MIT License – use freely, modify as needed, no warranties.
+
+---
+
+Created and maintained by a privacy-conscious, security-oriented Linux sysadmin.