Bash Script Examples: A Beginner's Guide to Automation

Bash scripting is one of the most valuable skills for Linux users, system administrators, and DevOps engineers. It allows you to automate repetitive tasks, schedule processes, and improve overall system efficiency. Whether you're looking to streamline server maintenance or automate daily tasks, learning how to create Bash scripts can save you significant time and effort.

This guide will introduce you to Bash scripting essentials, provide several examples, and explain how to run Bash scripts on a Linux server. In the end, you'll discover how to deploy and run Bash scripts on a SurferCloud VPS for enhanced performance and flexibility.

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What is a Bash Script?

A Bash script is a plain text file containing a sequence of commands that are executed sequentially by the Bash shell. Instead of typing commands one by one, you can store them in a script file and run them as a program. Bash scripts are typically used to automate server maintenance, backups, file manipulations, and more.

Bash scripts usually have a .sh file extension (for example, myscript.sh), but this is not strictly necessary. To execute the script, you need to give it the right permissions and run it from the terminal.

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How to Create a Bash Script

1. Create the Script File:
   Use a text editor like nano or vim to create a new file. nano myscript.sh
2. Add the Shebang Line:
   The first line of the script must specify the shell to be used. #!/bin/bash
3. Write Commands:
   Add the necessary Linux commands, variables, and logic. For example: #!/bin/bash echo "Hello, World!"
4. Make the Script Executable:
   Change the file permissions to make the script executable. chmod +x myscript.sh
5. Run the Script:
   Execute the script by typing: ./myscript.sh

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Basic Bash Script Examples

1. "Hello, World!" Script

The simplest Bash script example:

#!/bin/bash
echo "Hello, World!"

This script prints "Hello, World!" to the terminal.

2. Backup Files Script

This script creates a backup of a specific directory.

#!/bin/bash

SOURCE_DIR="/var/www/html"
BACKUP_DIR="/backup/$(date +%Y-%m-%d)"

mkdir -p $BACKUP_DIR
cp -r $SOURCE_DIR/* $BACKUP_DIR

echo "Backup completed. Files saved in $BACKUP_DIR"

How it works:

• SOURCE_DIR and BACKUP_DIR are variables that store paths.
• mkdir -p creates a directory (including any parent directories that do not exist).
• cp -r copies files recursively from SOURCE_DIR to BACKUP_DIR.

3. Disk Space Check Script

This script checks disk space usage and sends an alert if usage exceeds 80%.

#!/bin/bash

THRESHOLD=80
USAGE=$(df / | grep / | awk '{ print $5 }' | sed 's/%//')

if [ $USAGE -gt $THRESHOLD ]; then
  echo "Disk space usage is above $THRESHOLD%. Current usage: $USAGE%."
fi

How it works:

• The df / command shows disk usage, and awk extracts the percentage of disk space used.
• If disk usage exceeds the threshold (80%), the script sends a message to the terminal.

4. User Login Alert Script

This script sends an alert when a new user logs in.

#!/bin/bash

who | while read user_info; do
    echo "User Login Detected: $user_info"
done

How it works:

• The who command lists currently logged-in users.
• The while read loop processes each login entry and prints an alert.

5. System Update Script

This script automatically updates system packages on Ubuntu.

#!/bin/bash

echo "Updating system packages..."
sudo apt-get update -y
sudo apt-get upgrade -y
echo "System update completed."

How it works:

• sudo apt-get update refreshes the package list.
• sudo apt-get upgrade installs available package updates.
• The -y option automatically answers "yes" to any prompts.

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Variables, Loops, and Conditionals in Bash

1. Variables: NAME="SurferCloud" echo "Welcome to $NAME"
2. Conditionals (if/else): if [ $1 -gt 10 ]; then echo "The argument is greater than 10" else echo "The argument is less than or equal to 10" fi
3. Loops: for i in 1 2 3 4 5; do echo "Loop number $i" done
4. Functions: greet_user() { echo "Welcome, $1!" } greet_user "John"

These structures are essential for creating dynamic and robust Bash scripts.

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How to Run Bash Scripts on a SurferCloud VPS

When it comes to running Bash scripts on a VPS, SurferCloud makes it easy. Here's how you can run a Bash script on a SurferCloud VPS:

1. Connect to Your VPS:
   Use SSH to connect to your VPS: ssh user@your-vps-ip
2. Create Your Bash Script:
   Once inside the VPS, create your script using a text editor like nano. nano script.sh
3. Add Script Commands:
   Write the commands you want to automate. For example: #!/bin/bash echo "Running maintenance tasks"
4. Make the Script Executable: chmod +x script.sh
5. Run the Script: ./script.sh
6. Schedule Script Execution (Optional):
   To run the script at specific intervals, use cron jobs: crontab -e Add the following line to run the script every day at 2 a.m.: 0 2 * * * /path/to/script.sh

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Why SurferCloud is the Perfect Choice for Running Bash Scripts

If you want to run Bash scripts on a secure, high-performance VPS, SurferCloud is the perfect option. Here’s why:

• Global Data Centers: Choose from 16 locations worldwide for low-latency connections.
• Powerful VPS Plans: SurferCloud offers plans from 1 CPU and 1GB RAM to 64 CPU and 512GB RAM, supporting all Bash scripting needs.
• Enterprise-Grade Security: Benefit from DDoS protection and firewalls for uninterrupted service.
• Flexible Pricing: Choose hourly or monthly billing, with simple and transparent pricing.
• User-Friendly Dashboard: Easily create, manage, and monitor VPS instances through an intuitive control panel.

With SurferCloud, you get the reliability and performance required for running powerful Bash scripts at scale.

Get started with SurferCloud VPS and deploy your first Bash script in just minutes!

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Conclusion

Bash scripting is an essential skill for anyone managing Linux servers. It simplifies repetitive tasks, automates maintenance, and saves valuable time. With this guide, you’ve learned how to create, run, and automate Bash scripts for various use cases like backups, updates, and user monitoring.

If you want a fast, secure, and global platform to run your Bash scripts, SurferCloud VPS is the way to go. It offers low-latency servers, robust security, and flexible configurations for developers, DevOps engineers, and system administrators.