Backups are crucial for data security and disaster recovery. Whether you're safeguarding personal files or managing production environments, automating backups reduces risk and ensures data integrity.
In this blog, we’ll explore an industry-standard Bash script for automated, incremental backups using rsync, following best practices such as:
✔ Function-based scripting for readability and reusability
✔ Efficient incremental backups using rsync
✔ Automated backup rotation (retaining only the last 3 backups)
✔ Error handling and logging for reliability
Why Use Rsync for Backups?
Unlike full backups (e.g., ZIP-based archives), rsync efficiently synchronizes only changed files, making it:
- Faster – Transfers only modified data
- Storage-efficient – Keeps incremental backups, saving disk space
- Versatile – Supports remote backups over SSH
The Rsync Backup Script
Below is a function-based industry-standard Bash script that automates incremental backups with a 3-day retention policy.
🔹 Script: backup_and_rotation_rsync.sh
#! /bin/bash << readme This is an industry-standard script for incremental backups using rsync with a 3-day rotation. Usage: ./backup_and_rotation_rsync.sh <path to your source> <path to backup folder> readme # Function to display usage information function display_usage { echo "Usage: ./backup_and_rotation_rsync.sh <path to your source> <path to backup folder>" } # Check if the correct number of arguments is provided if [ $# -ne 2 ]; then display_usage exit 1 fi # Assign arguments to variables source_dir=$1 backup_dir=$2 timestamp=$(date '+%Y-%m-%d-%H-%M-%S') backup_target="${backup_dir}/backup_${timestamp}" log_file="${backup_dir}/backup_${timestamp}.log" # Function to check if rsync is installed function check_rsync_installed { if ! command -v rsync > /dev/null 2>&1; then echo "Error: rsync is not installed. Please install it and try again." >&2 exit 2 fi } # Function to create a backup using rsync function create_backup { mkdir -p "$backup_target" # Ensure backup directory exists rsync -av --delete "$source_dir/" "$backup_target/" > "$log_file" 2>&1 if [ $? -eq 0 ]; then echo "Backup completed successfully at $backup_target" else echo "Backup failed! Check log: $log_file" >&2 exit 3 fi } # Function to perform backup rotation (retain only the last 3 backups) function perform_rotation { backups=("${backup_dir}"/backup_*) # Find existing backups backups=($(ls -td "${backups[@]}" 2>/dev/null)) # Sort backups by timestamp (newest first) echo "Existing backups: ${backups[@]}" if [ "${#backups[@]}" -gt 3 ]; then echo "Performing rotation: Keeping latest 3 backups" backups_to_remove=("${backups[@]:3}") # Keep latest 3 backups echo "Removing backups: ${backups_to_remove[@]}" for backup in "${backups_to_remove[@]}"; do rm -rf "${backup}" done fi } # Run the functions in order check_rsync_installed create_backup perform_rotation Step-by-Step Explanation
1️⃣ Argument Validation
if [ $# -ne 2 ]; then display_usage exit 1 fi The script requires two arguments:
- Source directory – Folder to back up
- Backup directory – Where backups will be stored
- If not provided, it displays the correct usage and exits.
2️⃣ Checking Rsync Installation
function check_rsync_installed { if ! command -v rsync > /dev/null 2>&1; then echo "Error: rsync is not installed. Please install it and try again." >&2 exit 2 fi } Since rsync is essential for this script, we check if it's installed. If not, an error message prompts the user to install it.
3️⃣ Creating the Backup
function create_backup { mkdir -p "$backup_target" # Ensure backup directory exists rsync -av --delete "$source_dir/" "$backup_target/" > "$log_file" 2>&1 } - rsync -av preserves permissions, timestamps, and symbolic links.
- --delete removes files in the backup that no longer exist in the source.
- Logs are saved for later review.
4️⃣ Backup Rotation (Keeping Only Last 3 Backups)
function perform_rotation { backups=("${backup_dir}"/backup_*) backups=($(ls -td "${backups[@]}" 2>/dev/null)) # Sort backups by timestamp (newest first) if [ "${#backups[@]}" -gt 3 ]; then backups_to_remove=("${backups[@]:3}") # Keep latest 3 backups for backup in "${backups_to_remove[@]}"; do rm -rf "${backup}" done fi } This ensures only the latest 3 backups are retained by:
✅ Sorting backups by timestamp
✅ Keeping the latest 3
✅ Deleting older backups automatically
⏳ How to Use This Script
1️⃣ Make the script executable
chmod +x backup_and_rotation_rsync.sh 2️⃣ Run the script with the source and backup folder paths
./backup_and_rotation_rsync.sh /home/user/documents /backups 3️⃣ Check backup logs
cat /backups/backup_YYYY-MM-DD-HH-MM-SS.log 
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