🤖 Bash Scripting Basics for Automation in AlmaLinux: Beginner’s Journey

Ever felt like you’re doing the same commands over and over? 😩 Well, guess what - that’s exactly why bash scripting exists! I still remember my first script… It was just three lines, but when it worked? Man, I felt like a wizard! 🧙‍♂️ Today, I’m gonna show you how to write bash scripts that’ll automate all those boring tasks. And honestly? It’s easier than you think!

🤔 Why is Bash Scripting Important?

Let me tell you something - bash scripting changed my life. Okay, maybe that’s dramatic, but seriously, it’s THAT useful! Here’s why you need this:

• 🤖 Automate Everything - Stop typing the same commands daily
• ⏰ Save Hours - Let scripts do the work while you drink coffee
• 🎯 Fewer Mistakes - Scripts don’t have typos (once they work!)
• 💪 Feel Powerful - Control your system like a boss
• 📈 Career Boost - Every IT job loves automation skills
• 🚀 Work Smarter - Not harder, right?

Plus, there’s something really satisfying about watching your script do in seconds what used to take minutes! 😎

🎯 What You Need

Before we start scripting (and trust me, this is gonna be fun!), let’s check you have:

• ✅ AlmaLinux system ready to go
• ✅ Terminal access (we’ll live here!)
• ✅ Text editor (nano, vim, or whatever you like)
• ✅ 20 minutes to change your life (not kidding!)
• ✅ Willingness to make mistakes (that’s how we learn!)

📝 Step 1: Your First Bash Script

Alright, let’s write your first script! Don’t worry, we’ll start super simple.

Create Your First Script

# Create a script file
nano ~/my-first-script.sh

# Type this in the file:
#!/bin/bash
# My very first bash script!

echo "Hello from my script! 👋"
echo "Today is: $(date)"
echo "You are: $(whoami)"
echo "Your home is: $HOME"

Make It Executable

# Give execute permission
chmod +x ~/my-first-script.sh

# Run your script!
./my-first-script.sh

# You'll see:
# Hello from my script! 👋
# Today is: Mon Aug 19 15:30:45 EDT 2025
# You are: yourname
# Your home is: /home/yourname

Boom! You’re a scripter now! 🎉

Understanding the Shebang

#!/bin/bash  # This is the "shebang" - tells system to use bash

# You might also see:
#!/usr/bin/env bash  # More portable version
#!/bin/sh           # For POSIX shell (more basic)

🔧 Step 2: Variables and User Input

Variables are like containers for your data. Let’s play with them!

Basic Variables

nano ~/variables-demo.sh

#!/bin/bash
# Learning about variables

# Simple variables (no spaces around =)
name="AlmaLinux"
version=9
is_awesome=true

# Using variables (need $ to access)
echo "I'm using $name version $version"
echo "Is it awesome? $is_awesome"

# Command output in variables
current_date=$(date +%Y-%m-%d)
file_count=$(ls | wc -l)

echo "Today is: $current_date"
echo "Files in current directory: $file_count"

Getting User Input

nano ~/user-input.sh

#!/bin/bash
# Getting input from user

echo "What's your name? 🤔"
read user_name

echo "How old are you?"
read user_age

echo "Nice to meet you, $user_name!"
echo "Wow, $user_age years young! 🎂"

# Fancy input with prompt
read -p "What's your favorite color? " fav_color
echo "I love $fav_color too!"

# Secret input (for passwords)
read -s -p "Enter password: " password
echo ""  # New line after hidden input
echo "Password length: ${#password} characters"

🌟 Step 3: Conditions (If/Then/Else)

Time to make decisions in your scripts! This is where it gets interesting.

Basic If Statement

nano ~/check-disk.sh

#!/bin/bash
# Check disk space

# Get disk usage percentage
disk_usage=$(df -h / | awk 'NR==2 {print $5}' | sed 's/%//')

echo "Current disk usage: $disk_usage%"

if [ $disk_usage -gt 80 ]; then
    echo "⚠️ WARNING: Disk space is running low!"
elif [ $disk_usage -gt 60 ]; then
    echo "📊 Disk usage is moderate. Keep an eye on it."
else
    echo "✅ Plenty of disk space available!"
fi

Checking Files and Directories

nano ~/file-checker.sh

#!/bin/bash
# File and directory checker

file_to_check="$1"  # First argument passed to script

if [ -z "$file_to_check" ]; then
    echo "Usage: $0 <filename>"
    exit 1
fi

# Different file checks
if [ -e "$file_to_check" ]; then
    echo "✅ $file_to_check exists!"
    
    if [ -f "$file_to_check" ]; then
        echo "   📄 It's a regular file"
        echo "   Size: $(ls -lh "$file_to_check" | awk '{print $5}')"
    elif [ -d "$file_to_check" ]; then
        echo "   📁 It's a directory"
        echo "   Contains: $(ls "$file_to_check" | wc -l) items"
    fi
    
    if [ -r "$file_to_check" ]; then
        echo "   👀 Readable"
    fi
    if [ -w "$file_to_check" ]; then
        echo "   ✏️ Writable"
    fi
    if [ -x "$file_to_check" ]; then
        echo "   🏃 Executable"
    fi
else
    echo "❌ $file_to_check doesn't exist!"
fi

✅ Step 4: Loops - Do Things Repeatedly

Loops are where bash scripting really shines! Let’s automate repetitive tasks.

For Loops

nano ~/backup-files.sh

#!/bin/bash
# Backup important files

# Create backup directory
backup_dir="$HOME/backups/$(date +%Y%m%d)"
mkdir -p "$backup_dir"

# List of files to backup
files_to_backup=(
    "/etc/hosts"
    "/etc/resolv.conf"
    "$HOME/.bashrc"
    "$HOME/.bash_profile"
)

# Loop through and backup each file
for file in "${files_to_backup[@]}"; do
    if [ -f "$file" ]; then
        echo "📦 Backing up: $file"
        cp "$file" "$backup_dir/" 2>/dev/null && echo "   ✅ Success!" || echo "   ❌ Failed!"
    else
        echo "⚠️ Skipping $file (not found)"
    fi
done

echo "🎉 Backup complete! Files saved to: $backup_dir"

While Loops

nano ~/monitor-service.sh

#!/bin/bash
# Monitor a service

service_name="httpd"  # Change to your service
check_interval=5      # Seconds between checks
max_checks=10        # Maximum number of checks

counter=0
echo "👀 Monitoring $service_name service..."

while [ $counter -lt $max_checks ]; do
    if systemctl is-active --quiet "$service_name"; then
        echo "✅ [$counter/$max_checks] $service_name is running"
    else
        echo "❌ [$counter/$max_checks] $service_name is DOWN!"
        # Try to restart
        echo "   🔄 Attempting restart..."
        sudo systemctl start "$service_name"
    fi
    
    ((counter++))
    sleep $check_interval
done

echo "Monitoring complete after $max_checks checks"

🎮 Quick Examples

Example 1: System Info Script 💻

nano ~/system-info.sh

#!/bin/bash
# Complete system information script

echo "======================================"
echo "     🖥️ SYSTEM INFORMATION REPORT"
echo "======================================"
echo ""

# Hostname and OS
echo "📍 Hostname: $(hostname)"
echo "🐧 OS: $(cat /etc/redhat-release)"
echo "🏗️ Kernel: $(uname -r)"
echo ""

# CPU Info
echo "🧠 CPU Information:"
echo "   Model: $(lscpu | grep 'Model name' | cut -d':' -f2 | xargs)"
echo "   Cores: $(nproc)"
echo "   Load: $(uptime | awk -F'load average:' '{print $2}')"
echo ""

# Memory
echo "💾 Memory Usage:"
free -h | grep "^Mem:" | awk '{print "   Total: "$2"\n   Used: "$3"\n   Free: "$4}'
echo ""

# Disk
echo "💿 Disk Usage:"
df -h / | awk 'NR==2 {print "   Total: "$2"\n   Used: "$3"\n   Available: "$4"\n   Usage: "$5}'
echo ""

# Network
echo "🌐 Network Interfaces:"
ip -4 addr show | grep inet | grep -v 127.0.0.1 | awk '{print "   "$NF": "$2}'
echo ""

# Top processes
echo "📊 Top 5 CPU-hungry processes:"
ps aux | sort -rk 3,3 | head -6 | tail -5 | awk '{print "   "$11" ("$3"%)"}'
echo ""

echo "======================================"
echo "Report generated: $(date)"

Example 2: Automated Backup Script 📦

nano ~/smart-backup.sh

#!/bin/bash
# Smart backup script with rotation

# Configuration
SOURCE_DIR="$HOME/Documents"
BACKUP_BASE="$HOME/Backups"
MAX_BACKUPS=7  # Keep only 7 days of backups

# Create backup filename with date
BACKUP_NAME="backup-$(date +%Y%m%d-%H%M%S).tar.gz"
BACKUP_PATH="$BACKUP_BASE/$BACKUP_NAME"

# Function to clean old backups
cleanup_old_backups() {
    echo "🧹 Cleaning old backups..."
    cd "$BACKUP_BASE"
    ls -t backup-*.tar.gz 2>/dev/null | tail -n +$((MAX_BACKUPS + 1)) | xargs -r rm -v
}

# Main backup process
echo "🚀 Starting backup process..."
echo "   Source: $SOURCE_DIR"
echo "   Destination: $BACKUP_PATH"

# Create backup directory if needed
mkdir -p "$BACKUP_BASE"

# Check if source exists
if [ ! -d "$SOURCE_DIR" ]; then
    echo "❌ Error: Source directory doesn't exist!"
    exit 1
fi

# Create the backup
echo "📦 Creating backup..."
tar -czf "$BACKUP_PATH" -C "$(dirname "$SOURCE_DIR")" "$(basename "$SOURCE_DIR")" 2>/dev/null

if [ $? -eq 0 ]; then
    SIZE=$(ls -lh "$BACKUP_PATH" | awk '{print $5}')
    echo "✅ Backup created successfully! Size: $SIZE"
    
    # Clean old backups
    cleanup_old_backups
    
    # Show current backups
    echo "📋 Current backups:"
    ls -lh "$BACKUP_BASE"/backup-*.tar.gz | tail -5
else
    echo "❌ Backup failed!"
    exit 1
fi

Example 3: User Management Script 👥

nano ~/user-manager.sh

#!/bin/bash
# Interactive user management script

show_menu() {
    echo ""
    echo "========================================="
    echo "     👥 USER MANAGEMENT MENU"
    echo "========================================="
    echo "1) 📋 List all users"
    echo "2) ➕ Create new user"
    echo "3) 🔐 Change user password"
    echo "4) 👀 Show user info"
    echo "5) ❌ Delete user"
    echo "6) 🚪 Exit"
    echo "========================================="
}

# Function to list users
list_users() {
    echo "📋 System users (UID >= 1000):"
    awk -F: '$3 >= 1000 {print "   👤 " $1 " (UID: " $3 ")"}' /etc/passwd
}

# Function to create user
create_user() {
    read -p "Enter username: " username
    
    if id "$username" &>/dev/null; then
        echo "❌ User $username already exists!"
    else
        sudo useradd -m "$username"
        echo "✅ User $username created!"
        read -p "Set password now? (y/n): " setpass
        if [[ $setpass == "y" ]]; then
            sudo passwd "$username"
        fi
    fi
}

# Main loop
while true; do
    show_menu
    read -p "Choose option (1-6): " choice
    
    case $choice in
        1) list_users ;;
        2) create_user ;;
        3) 
            read -p "Username: " username
            sudo passwd "$username"
            ;;
        4)
            read -p "Username: " username
            id "$username" 2>/dev/null || echo "User not found!"
            ;;
        5)
            read -p "Username to delete: " username
            read -p "Are you sure? (yes/no): " confirm
            if [[ $confirm == "yes" ]]; then
                sudo userdel -r "$username" 2>/dev/null && echo "✅ Deleted!" || echo "❌ Failed!"
            fi
            ;;
        6) 
            echo "👋 Goodbye!"
            exit 0
            ;;
        *)
            echo "❌ Invalid option!"
            ;;
    esac
done

🚨 Fix Common Problems

Problem 1: “Permission denied” ❌

Your script won’t run?

# Check permissions
ls -l script.sh

# Fix it!
chmod +x script.sh

# Or run with bash directly
bash script.sh

Problem 2: “Command not found” ❌

Script can’t find commands?

# Add full paths in script
/usr/bin/echo "Hello"  # Instead of just 'echo'

# Or set PATH at script beginning
#!/bin/bash
PATH=/usr/bin:/bin:/usr/sbin:/sbin:$PATH

Problem 3: Variables Not Working ❌

Variables acting weird? Here’s why:

# WRONG - spaces around =
name = "John"  # This won't work!

# RIGHT - no spaces
name="John"

# WRONG - no $ when accessing
echo name  # Prints "name"

# RIGHT - use $
echo $name  # Prints "John"
echo ${name}  # Also works, better for complex cases

Problem 4: Script Hangs Forever ❌

# Add timeout to commands
timeout 5 ping google.com

# Add counter to loops
max_attempts=10
counter=0
while [ $counter -lt $max_attempts ]; do
    # Your code here
    ((counter++))
done

# Always have exit condition!

📋 Simple Commands Summary

💡 Tips for Success

1. Start Small 🐣 - Don’t try to automate everything at once
2. Test Often 🧪 - Run your script after each change
3. Use Comments 📝 - Future you will thank present you!
4. Error Handling 🛡️ - Always check if commands succeeded
5. Backup First 💾 - Before your script changes files
6. Debug Mode 🐛 - Use bash -x to see what’s happening

Honestly? My first scripts were terrible. But you know what? They worked! And that’s all that matters when you’re learning. 😊

🏆 What You Learned

Holy cow, look what you can do now:

• ✅ Write and run bash scripts
• ✅ Use variables and get user input
• ✅ Make decisions with if/then/else
• ✅ Create loops for repetitive tasks
• ✅ Build real automation scripts
• ✅ Debug when things go wrong
• ✅ Create interactive menus

🎯 Why This Matters

Here’s the thing - bash scripting literally changes how you work:

• 🚀 Automate boring daily tasks
• ⏰ Schedule scripts with cron for total automation
• 💼 Essential skill for any Linux job
• 🧠 Think like a programmer
• 💰 Save hours every week
• 😎 Impress everyone with your automation skills

You know what happened last month? I wrote a script that automated our backup process. What used to take an hour every Friday now runs automatically at 2 AM. My manager thinks I’m some kind of wizard! 🧙‍♂️ And honestly? You can do this too!

Remember: Every expert scripter started with “Hello World”. Keep practicing, keep experimenting, and don’t be afraid to break things (in a test environment!). You’re on your way to becoming an automation master! 🌟

Happy scripting! May your scripts run flawlessly and your automation dreams come true! 🤖🚀