Day 5: Advanced Linux Shell Scripting for DevOps Engineers with User Management

Hello, DevOps Enthusiasts! 👋

As part of my #90DaysOfDevOps challenge, I dived into Advanced Linux Shell Scripting today, focusing on directory creation, backups, automation with crontab, and user management. Here's a detailed walkthrough of today's tasks and my solutions.

📌 Task 1: Create Directories Using Shell Script

Objective:

Create a bash script createDirectories.sh to generate a specified number of directories dynamically based on user inputs.

Code:

#!/bin/bash

<<Info
Author       : Amitabh Soni  
Date         : 25/11/24  
Description  : This script takes three arguments and creates a specified number of directories at once.  

Example      :  
./createDirectories.sh day 1 90 → Creates directories day1, day2, ..., day90.  
Info

# Loop through the range of directory numbers
for i in $(seq $2 $3); do
    mkdir "$1$i"
done

Example Execution:

• ./createDirectories.sh day 1 90 → Creates day1 to day90.

• ./createDirectories.sh Movie 20 50 → Creates Movie20 to Movie50.

Check out the script and output images below:

📌 Task 2: Backup Script

Objective:

Write a script to back up a directory or file and save it in a predefined backup folder.

Code:

#!/bin/bash

<<Info
Author       : Amitabh Soni  
Date         : 25/11/24  
Description  : This script creates a zip backup of a directory or file and stores it in the backup directory.  
Info

# Function to create a backup
function create_backup() {
    timestamp=$(date '+%Y-%m-%d_%H-%M-%S')  
    target_dir="/home/ubuntu/Day-05/backup"  
    backup_file="${target_dir}/backup_${timestamp}.zip"  

    # Create the zip file
    zip -r "$backup_file" "$1"  

    if [ $? -eq 0 ]; then
        echo "Backup created: $backup_file"  
    else
        echo "Error: Backup failed."  
    fi
}

create_backup "$1"

Steps:

1. Save the script as backup.sh.

2. Run it with the directory or file you want to back up:

    ./backup.sh /path/to/directory_or_file
   

Output:

• Script execution screenshot:

  

• Backup folder after execution:

  

📌 Task 3: Automating Backups with Cron and Crontab

Objective:

Automate the backup.sh script to run at regular intervals using crontab.

Steps:

1. Open the crontab editor:

    crontab -e
   

2. Add the following line to run the backup every minute:

    * * * * * /path/to/backup.sh /path/to/directory_or_file
   

Verifications:

• Watching real-time backups with watch ls:

  

• Final backup check:

  

📌 Task 4: User Management in Linux

Objective:

Create two users and display their usernames.

Steps:

1. Use adduser command to create users:

    sudo adduser username1  
    sudo adduser username2
   

2. Display usernames:

    cut -d: -f1 /etc/passwd | tail -2
   

Execution:

• Adding users:

  

• Password setup:

💡 Key Learnings:

• Leveraged shell scripting for dynamic tasks like directory creation and backups.

• Automated routine tasks with cron and crontab.

• Explored the fundamentals of Linux user management.

🔗 Check Out My Progress:

• LinkedIn

• GitHub Repo (Pull request)

Stay tuned for more updates from my #90DaysOfDevOps challenge! 🚀

What do you think about these tasks? Feel free to share your thoughts or ask questions in the comments below! 😊