Day 9 Task: Shell Scripting Challenge Directory Backup with Rotation

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Challenge Description

The task is to create a bash script that takes a directory as a command-line argument and performs a backup. The script should create timestamped backup folders and copy all the files from the specified directory into the backup folder. Additionally, it should implement a rotation mechanism to keep only the last 3 backups.

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Steps 🚀

1. Create a Folder and Make Some Files

First, you'll need to create a directory with some files to simulate the data that will be backed up. 📂 Use the following commands to create the directory and files: 💻

mkdir /root/datafile
touch /root/datafile/file1.txt
touch /root/datafile/file2.txt

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2. Install zip (if not already installed) 📦

Before running the script, ensure that zip is installed, as it will be used to compress the backups. To check if zip is installed, type: 🔍

zip

If zip is not installed, install it using:

sudo apt install zip

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3. crontab Job Scheduling 🕒

You can schedule your backup script to run periodically using crontab. For example, if you want the script to run every hour, do the following: ⏰

1. Open crontab for editing:

    crontab -e
   

2. Add the following line to schedule the job to run every hour:

    * 1 * * * bash /root/backup.sh /root/datafile /root/backup
   

This will run your backup script every hour and store backups in /root/backup.

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4. Bash Script for Backup and Rotation 🛠️

Here is the bash script that will create timestamped backups and implement a rotation mechanism to delete older backups, keeping only the last 3 backups. 🔄📅

#!/bin/bash

# Check if the required directories are provided
if [ -z "$1" ] || [ -z "$2" ]; then
    echo "Usage: $0 <source_directory> <backup_directory>"
    exit 1
fi

SOURCE_DIR="$1"
BACKUP_DIR="$2"
TIMESTAMP=$(date +"%Y-%m-%d_%H-%M-%S")
BACKUP_NAME="backup_$TIMESTAMP.zip"
BACKUP_PATH="$BACKUP_DIR/$BACKUP_NAME"

# Create a backup of the source directory
zip -r "$BACKUP_PATH" "$SOURCE_DIR"

# Output the backup creation message
echo "Backup created: $BACKUP_PATH"

# Implement backup rotation - Keep only the last 3 backups
BACKUP_COUNT=$(ls -1 "$BACKUP_DIR" | grep "backup_.*.zip" | wc -l)

if [ "$BACKUP_COUNT" -gt 3 ]; then
    # Delete the oldest backups
    ls -1t "$BACKUP_DIR"/backup_*.zip | tail -n +4 | xargs rm
    echo "Old backups removed, keeping only the last 3 backups."
fi

Explanation: 📄

1. Backup Creation: 💾

   • The script takes two arguments: the source directory and the backup directory. 📂

   • It generates a timestamp and creates a zip file of the source directory in the backup directory with a name like backup_YYYY-MM-DD_HH-MM-SS.zip. 🕒

   • It uses the zip command to compress the backup. 📦

2. Backup Rotation: 🔄

   • The script checks how many backup files exist in the backup directory. 📊

   • If there are more than 3 backups, the script deletes the oldest backups and retains only the 3 most recent backups. 🗑️✨

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5. Example Crontab Job 🕒

To run this script automatically every hour, add the following line to your crontab: ⏰

* 1 * * * bash /root/backup.sh /root/datafile /root/backup

This will ensure that backups are created every hour ⏰ and that older backups are rotated out 🔄, keeping only the latest three. 📂✨