Backup Script with 5-Day Rotation

Introduction

This script automates the process of creating backups for a specified directory and implements a backup rotation mechanism to manage storage space efficiently.

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What is Backup Rotation?

Backup rotation is a process of systematically managing backups by retaining only the most recent copies and deleting older ones. This approach ensures:

1. Efficient Storage Utilization: Prevents disk space from being consumed by redundant backups.
2. Quick Recovery: Ensures access to recent backups without shifting through outdated copies.
3. Streamlined Maintenance: Simplifies the process of managing backup files.

By limiting the number of backups retained (e.g., the last 5), backup rotation achieves a balance between redundancy and storage efficiency.

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Why is Backup Rotation Required?

1. Limited Storage Capacity: Disk space is finite; retaining too many backups can exhaust available space quickly.
2. Prevent Redundancy: Keeping excessive backups often results in duplication and unnecessary clutter.
3. Focus on Relevance: Only the most recent backups are typically useful for recovery.
4. Maintenance Efficiency: Automating the rotation reduces manual intervention, saving time and effort.

Without backup rotation, backup systems may become unsustainable over time, leading to storage constraints and inefficiencies.

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About This Code

This script creates compressed backups of a source directory and retains only the latest 5 backups in the target directory. The older backups are automatically deleted to optimize storage space.

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Features

1. Automated Backup Creation: Compresses the source directory into a zip file with a timestamped name.
2. Backup Rotation: Ensures only the 5 most recent backups are retained.
3. Error Handling: Provides clear error messages if something goes wrong during backup creation or file deletion.

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Explanation of the Code Setup

1. Source Directory Setup:

   • A directory named data was created at /home/ubuntu/.
   • This directory (/home/ubuntu/data) contains 5 files: file1.txt, file2.txt, file3.txt, file4.txt, and file5.txt.

2. Script File:

   • A script file named backup.sh was created in /home/ubuntu/.
   • This file contains the backup and rotation code described in this document.

3. Destination Directory Setup:

   • A directory named backups was created at /home/ubuntu/.
   • This directory (/home/ubuntu/backups) is where all the backups are stored.
   • After running the script, the backups are compressed into zip files and saved in this directory. The rotation mechanism ensures that only the latest 5 backups are retained.

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How the Script Works

1. Usage Check: Validates that the source and backup directories are provided as arguments.
2. Backup Rotation:
   • Lists all existing backups in the target directory.
   • Deletes backups if there are more than 5, starting with the oldest.
3. Backup Creation:
   • Creates a compressed zip file of the source directory, named with the current timestamp.

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Code Walkthrough

Functions

1. display_usage:

   • Displays usage instructions if incorrect arguments are provided.

2. perform_rotation:

   • Checks the number of backups in the target directory.
   • Deletes backups exceeding the 5 most recent files.

3. create_backup:

   • Creates a timestamped zip file of the source directory in the backup directory.

Execution Flow

1. Validate arguments.
2. Execute perform_rotation to clean up old backups.
3. Execute create_backup to generate a new backup.

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Usage

Script Arguments

1. <path to source>: The directory to be backed up.
2. <path to backup>: The directory where the backup will be stored.

Example

./backup.sh /home/ubuntu/data /home/ubuntu/backups

Setting Executable Permissions

Before running the script, ensure it has executable permissions:

chmod +x backup.sh

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Benefits

1. Automates regular backups with minimal user intervention.
2. Prevents clutter in the backup directory by keeping only relevant files.
3. Ideal for systems with limited storage space.

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Limitations

• Requires zip to be installed on the system.
• Backup rotation is limited to 5 files by default (modifiable in the script).

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Future Enhancements

• Add email notifications for backup completion or failures.
• Support for incremental backups to reduce storage space further.
• Make the number of backups retained configurable through arguments or a configuration file.