Timestamped Directory Backup with Rsync

#!/bin/bash

SOURCE_DIR="/var/www/mywebapp" # Directory to back up
BACKUP_ROOT_DIR="/mnt/backups/webapp" # Root directory for backups
DATE_SUFFIX=$(date +"%Y%m%d_%H%M%S")
BACKUP_TARGET_DIR="$BACKUP_ROOT_DIR/backup_$DATE_SUFFIX"
LATEST_LINK="$BACKUP_ROOT_DIR/latest" # Symlink to the latest backup

# Create backup root directory if it doesn't exist
mkdir -p "$BACKUP_ROOT_DIR"

echo "--- Starting backup of '$SOURCE_DIR' to '$BACKUP_TARGET_DIR' ---"

# Use rsync for efficient backup (e.g., --link-dest for incremental backups)
if [ -e "$LATEST_LINK" ]; then
    echo "Performing incremental backup..."
    # --archive: recursive, copy symlinks, preserve permissions, modification times, group, owner
    # --human-readable: output numbers in a human-readable format
    # --delete-excluded: delete excluded files on the receiving side
    # --exclude: exclude specific files/directories (e.g., node_modules, .git)
    # --link-dest: hardlink files that are unchanged from the previous backup
    rsync -avh --delete-excluded \
        --exclude='node_modules/' \
        --exclude='.git/' \
        --exclude='vendor/' \
        --link-dest="$LATEST_LINK" "$SOURCE_DIR/" "$BACKUP_TARGET_DIR/"
else
    echo "Performing full backup (first backup)..."
    rsync -avh --delete-excluded \
        --exclude='node_modules/' \
        --exclude='.git/' \
        --exclude='vendor/' \
        "$SOURCE_DIR/" "$BACKUP_TARGET_DIR/"
fi

# Update the 'latest' symlink
rm -f "$LATEST_LINK"
ln -s "$BACKUP_TARGET_DIR" "$LATEST_LINK"

echo "Backup completed successfully."
echo "Latest backup available at: $LATEST_LINK"
echo "--------------------------------------------------"