Welcome to Week 3 of the 90DaysOfDevOps – 2025 Edition! This week was all about Shell Scripting — one of the most powerful tools in a DevOps engineer’s toolkit. 🧑‍💻⚙️

Let’s break down Linux automation using Bash scripts — for user management, backups, and more — in the simplest way possible!

🐧 What is Shell Scripting in DevOps?

Shell scripting allows us to automate repetitive system admin tasks like:

Creating/deleting users
Resetting passwords
Taking backups
Scheduling tasks with cron

Instead of running 10 commands manually, you can write a script and run it once — saving time and avoiding mistakes. ✅

📘 1. User Account Management Script

Imagine you’re a system admin managing 100s of users. Doing everything manually would be exhausting.

So, I created a script:
user_management.sh – Your personal assistant for account management!

✨ Features Implemented:

Feature	What It Does
`--create`	Create a new user account
`--delete`	Delete an existing user
`--reset`	Reset password for a user
`--list`	Show all users with UID
`--help`	Show usage info

🧩 Real-Life Analogy:

Task	Real Life Example
Create User	Adding a new employee to a company
Reset Password	Giving them a new ID card
Delete User	Removing them from the system
List Users	Viewing employee directory

🛠 Sample Usage

bashCopyEdit./user_management.sh --create

Output:

pgsqlCopyEditEnter new username: devops_user
Enter password: ******
✅ User 'devops_user' created successfully!

🔐 Resetting Password

bashCopyEdit./user_management.sh --reset

pgsqlCopyEditEnter username to reset password: devops_user
Enter new password: ******
🔐 Password for 'devops_user' updated successfully.

📋 Listing Users

bashCopyEdit./user_management.sh --list

yamlCopyEditUsername: root, UID: 0
Username: devops_user, UID: 1001
Username: ubuntu, UID: 1002

☁️ 2. Backup with Rotation Script

Next, I created another script:
backup_with_rotation.sh – for safe and automated backups of any directory!

💡 Why Backups Matter?

If something breaks, a recent backup can save your project, your job, or even your company!

This script:

Creates a timestamped backup
Keeps only the last 3 backups
Can run daily via cron

🧪 Example:

bashCopyEdit./backup_with_rotation.sh /home/vaishnavi/documents

Output:

yamlCopyEdit✅ Backup created: backup_2025-08-06_13-45-20
🗑️ Deleted old backup: backup_2025-07-31_10-15-00

🧠 How It Works:

Step	Command
Create backup folder	`mkdir backup_$(date)`
Copy files	`cp -r source/* backup_folder/`
List backups	`ls -dt backup_*`
Keep only 3	`tail -n +4

🕒 Automating with Cron

To run the backup daily at 2:00 AM, I added this line using crontab -e:

bashCopyEdit0 2 * * * /home/vaishnavi/scripts/backup_with_rotation.sh /home/vaishnavi/documents

Now backups run automatically every day! 💥

🧰 3. Shell Scripting Cheatsheet

Command	Use
`read`	Take user input
`if` / `else`	Conditional checks
`case`	Menu-based options
`useradd`, `userdel`	Create/Delete users
`chpasswd`	Set passwords
`cron`	Schedule tasks

📝 Summary of Week 3

✅ Created CLI tool for Linux user management
✅ Automated backups with retention logic
✅ Scheduled tasks using cron
✅ Practiced writing production-grade Bash scripts

📢 Final Thoughts

Shell scripting is a DevOps superpower. Automate once, save hours forever. 🔁
Whether you're managing users or building CI/CD pipelines — Bash will always be by your side.

💡 "If you repeat a command more than twice — script it!"

📤 Connect With Me

🔗 Blog Series: https://hashnode.com/@VaishnaviTandekar
💻 GitHub Repo: 90DaysOfDevOps

🔖 Hashtags

#90DaysOfDevOps #ShellScripting #Bash #Automation #Linux #Cron #DevOpsBeginner #UserManagement #Backup

💻 DevOps Week 3: Shell Scripting for User Management & Backup Automation