Advanced Linux Shell Scripting + User Management

Have you ever wondered how DevOps engineers handle repetitive tasks like creating 90 folders or backing up large directories — without typing 90 commands?

Let me show you how Linux Shell Scripting, Cron jobs, and a few simple commands can automate hours of work in seconds.

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🔧 Challenge 1: Create 90 Directories Instantly

When you open the 2023 folder in the DevOps repository and notice 90 sub-directories — what do you think?

Were they created manually?
Nope. They were created in 1 second using:

mkdir day{1..90}

Just like that, 90 folders. One command. 💥
That’s the power of Bash and Shell Scripting.

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✍️ Task 1: createDirectories.sh – A Dynamic Directory Generator

Let’s create a reusable script that can generate any number of directories with custom names.

🛠️ Script: createDirectories.sh

#!/bin/bash

# Check if arguments are passed
if [ "$#" -ne 3 ]; then
  echo "Usage: $0 <DirectoryName> <StartNumber> <EndNumber>"
  exit 1
fi

prefix=$1
start=$2
end=$3

for i in $(seq $start $end)
do
  mkdir "${prefix}${i}"
done

🔄 How to Use:

chmod +x createDirectories.sh

# Example 1:
./createDirectories.sh day 1 90
# Creates day1 day2 ... day90

# Example 2:
./createDirectories.sh Movie 20 50
# Creates Movie20 Movie21 ... Movie50

Simple, dynamic, and fast. 🏃‍♂️💨

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📆 Task 2: Automating Your Backups with a Script

As a DevOps engineer, backups are your safety net.

Here’s how you can write a quick backup script that compresses your code, logs, or entire directory into a .tar.gz file.

🛠️ backup.sh Script

#!/bin/bash

# Backup directory
source_dir="/home/yourname/projects"
backup_dir="/home/yourname/backups"

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

# Create archive
tar -czf "$backup_dir/project_backup_$(date +%F).tar.gz" "$source_dir"

echo "Backup completed at $(date)"

Replace paths with your local setup. ✅

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🕒 Task 3: Automate Backup with cron

Crontab lets you run the backup script on a schedule. To open the crontab editor:

crontab -e

To run the backup daily at 10 PM:

0 22 * * * /home/yourname/backup.sh

Cron syntax can be tricky, but once you get it — you automate everything.

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👤 Task 4: User Management in Linux

DevOps = automation + security.
So you must know how to manage users in a Linux system.

👇 Commands to Create & Manage Users:

# Create users
sudo useradd user1
sudo useradd user2

# Set passwords
sudo passwd user1
sudo passwd user2

# Display usernames
cut -d: -f1 /etc/passwd | grep user

🧠 System users = UID 0–999
👤 Normal users = UID 1000+

User management = Access control, security, and scripting power 💪

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💡 What I Learned Today:

• You don’t need to repeat anything manually in Linux — write a script and let it fly.

• Backups are not optional in DevOps — they’re mission-critical.

• Cron is like your invisible assistant, automating everything silently.

• User management is the foundation of permission control in Linux.

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🔺 Final Thoughts

Shell scripting is one of the most underrated superpowers in DevOps.

It saves time, improves consistency, and prepares you for automation at scale.
Today's tasks may look simple, but they lay the foundation for real-world DevOps workflows.

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