Bash script – Everything You Need to Know 

Key highlights 

• Bash scripting automates tasks using a sequence of commands in a script file. Works on Unix-based systems like Linux and macOS. 
• Essential Bash commands include echo, ls, cd, pwd, grep and awk. 
• Cron jobs schedule scripts for automatic execution. 
• File backups and system automation are simplified with bash scripting. 
• Best practices include writing readable code, implementing proper error handling, debugging efficiently and ensuring security by restricting file permissions and avoiding hardcoded credentials. 
• Bluehost VPS provides a secure and reliable hosting environment for bash scripts. 

Introduction 

Are you tired of typing the same commands over and over again? Do you want to automate repetitive tasks and boost your productivity in Linux? If so, then bash scripting is your best friend! 

Bash, short for Bourne Again Shell, is a widely used Unix shell and scripting language. It allows users to execute commands, automate tasks and create complex programs for system administration. 

In this blog, we will cover everything you need to know about bash scripting—from writing your first script to automating system operations. Let’s dive in! 

What is bash scripting? 

A bash script is a plain text file containing a series of commands that are executed in sequence. Instead of manually entering commands in the terminal, you can write them in a script and execute them all at once. 

Bash scripts can handle: 

• File operations – creating, modifying and deleting files. 
• Process automation – scheduling jobs and automating deployments. 
• User interaction – taking input and displaying output dynamically. 

For example, the following simple bash script prints a greeting message: 

#!/bin/bash 
echo "Hello, welcome to bash scripting!" 

This script, when executed, will display the message in the terminal. 

Why use bash scripting? 

Bash scripting is one of the most powerful tools available for system administrators, developers and DevOps engineers. It allows you to automate tasks, manage processes and optimize system performance without requiring complex programming skills. Here’s why you should use bash scripting in your workflow: 

1. Automation: 

Performing the same tasks repeatedly is time-consuming and prone to human error. Bash scripting helps by automating these processes, ensuring they are executed consistently without user intervention. 

For example, if you regularly clean up temporary files on your system, you can automate the process with a script instead of manually deleting them each time: 

bash 
#!/bin/bash 
rm -rf /tmp/* 
echo "Temporary files cleaned up!" 
 

This script removes all temporary files from the /tmp/ directory every time it runs. You can even schedule it using cron jobs to execute automatically at a fixed interval. 

2. Efficiency: 

Instead of running multiple commands manually, a bash script can execute several commands sequentially with just one execution. This is particularly useful for server management, backups and system maintenance. 

For example, let’s say you need to update your system, clear caches and restart a service. Instead of running these commands one by one, you can combine them into a single script: 

bash
#!/bin/bash 
sudo apt update && sudo apt upgrade -y 
sudo systemctl restart apache2 
echo "System updated and Apache restarted successfully!" 
 

With just one command, you’ve performed three critical tasks, improving efficiency. 

3. Flexibility: 

One of the biggest advantages of bash scripting is that it works across multiple Unix-based operating systems, including: 

• Linux distributions (Ubuntu, Debian, CentOS, Fedora) 
• MacOS (Bash is available by default) 
• Cloud environments (AWS, Google Cloud, Azure) 
• Embedded Linux systems (Raspberry Pi, IoT devices) 

As long as a system has bash installed, your scripts can run seamlessly without modification, making bash a cross-platform solution. 

4. System management: 

System administrators often need to manage large amounts of files, move logs, delete unnecessary files and automate deployments. Bash scripts make these tasks easier and more efficient. 

For instance, if you want to move all .log files from one directory to another, a bash script can do it instantly: 

bash 
#!/bin/bash 
mv /var/logs/*.log /home/user/log_backup/ 
echo "All log files have been moved to the backup folder!" 
 

Instead of manually moving files, the script does it automatically, preventing mistakes and saving time. 

Similarly, bash scripts can automate software deployments, ensuring a fast and consistent deployment process. 

5. Scheduling 

Bash scripting is perfect for task scheduling, allowing you to set scripts to run at specific times using cron jobs. This is helpful for: 

• Automated backups 
• System health checks 
• Log file rotations 
• Running maintenance scripts 

For example, if you want to back up logs every night at 11:30 PM, you can schedule a bash script using cron: 

bash 
crontab -e 
30 23 * * * /home/user/backup_logs.sh 
 

This ensures that the backup script runs daily without requiring manual execution, automating critical system tasks. 

Prerequisites: Setting up your environment 

Before diving into writing bash scripts, you need to make sure your system is set up correctly. Let’s go through the basic requirements and installation steps. 

1. A Unix-based operating system (Linux/macOS) – bash comes pre-installed 

Bash is pre-installed on most Linux distributions and macOS systems. You can check if bash is installed on your system by running: 

bash 
bash --version 
 

If Bash is installed, you’ll see an output like this: 

scss 
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) 
 

This confirms that bash is ready to use! 

For Windows users, you need to install Git bash or enable Windows Subsystem for Linux (WSL) to use bash commands. 

Also read: The Best Linux Commands You Should Know for Effective Usage 

2. Choose a text editor for writing scripts 

To write bash scripts, you need a text editor. Here are the best options: 

Nano – Simple, beginner-friendly command-line editor. 
Vim – Powerful but requires learning its commands. 
VS Code – Graphical editor with bash extensions for better development. 

To create and edit a script using Nano, use: 

bash 
nano myscript.sh 
 

This will open a new script file where you can start writing your bash script. 

3. Basic command-line knowledge 

Before diving into scripting, it’s essential to understand some basic Linux and UNIX commands: 

Command	Description
cd	Change directories
ls	List files and directories
mkdir	Create a new directory
rm -rf	Delete files or directories
pwd	Print current directory
chmod +x file.sh	Make a script executable

A good understanding of these commands will make writing and debugging bash scripts much easier. 

4. Install bash (if not already installed) 

If bash is not installed on your system, you can install it manually using package managers: 

For Debian-based systems (Ubuntu, Debian, etc.): 

bash 
sudo apt update && sudo apt install bash 
 

For RHEL-based systems (CentOS, Fedora, etc.): 

bash 
sudo yum install bash 

Once installed, verify the installation by running: 

bash 
bash --version 
 

How to write bash scripts? 

Bash scripting and creating a shell script is a fundamental skill for working with the Unix system, allowing you to automate routine tasks and streamline system operations. Whether you’re a beginner writing a simple script or an advanced user managing system administration tasks, understanding the bash shell and its scripting capabilities is essential. 

Understanding the shebang (#!) 

The first line of a bash script is the shebang (#!), which tells the system which interpreter to use. 

bash 
#!/bin/bash 
 

Writing your first bash script 

1. Create a new script file: 

bash 
nano myscript.sh 
 

2. Add the following lines: 

bash 
#!/bin/bash 
echo "Hello, this is my first Bash script!" 
 

3. Save and exit (CTRL+X, then Y, then Enter). 

Making the script executable 

Grant execution permission: 

bash 
chmod +x myscript.sh 
 

How to run a bash script? 

Execute the script using: 

Bash 
./myscript.sh 
 

Or: 

bash 
bash myscript.sh 

How to get script directory in Bash? 

When writing scripts, you may need to determine the directory where the script is located, especially when dealing with file paths. You can use the following command to get the script’s directory: 

#!/bin/bash SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)" echo "Script directory: $SCRIPT_DIR" 

This ensures that the script can reference files relative to its own location, regardless of where it’s executed. 

What are the comments in bash scripts? 

Comments improve script readability. Single-line comments start with #: 

bash 
# This script prints a message 
echo "Hello, World!" 

Variables and data types 

Define variables in bash without spaces: 

bash 
name="Alice" 
echo "Hello, $name!" 
 

Bash supports strings, integers and arrays, but all variables are treated as strings by default. 

Conditional statements 

Conditional statements control the script’s execution based on conditions. 

bash 
age=20 
if [ $age -ge 18 ]; then 
    echo "You are an adult." 
else 
    echo "You are a minor." 
fi 

Loops in bash 

Loops are an essential component of shell scripting, allowing scripts to execute commands repeatedly based on conditions. Bash provides several looping mechanisms, along with a list of patterns to facilitate decision-making, with the most common being the for loop and while loop. 

For loop example, 

Loops execute commands multiple times. 

bash 
for i in {1..5}; do 
    echo "Iteration $i" 
done 
 

While loop example, 

bash 
count=1 
while [ $count -le 3 ]; do 
    echo "Count: $count" 
    ((count++)) 

done 

Functions, arguments and input/output 

Functions make code reusable. 

bash 
greet() { 
    echo "Hello, $1!" 
} 
greet "Alice" 
 

Read user input: 

bash 
read -p "Enter your name: " name 
echo "Welcome, $name!" 
 

Essential bash scripting commands 

When working with Bash scripting, including the basics of bash scripting, you’ll frequently use various shell commands to interact with the system, navigate directories, process text and automate tasks. Below, we’ll break down some of the most essential bash commands with detailed explanations and practical examples to help you get started. 

1. echo – Print text to terminal 

The echo command is one of the most fundamental bash commands, primarily used for printing text or variables to the terminal. It is frequently used in scripts to display messages, outputs or debugging information. 

Basic usage: 

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

Output: 

Hello, World! 
 

This command prints “Hello, World!” to the terminal. 

Printing variables: 

bash 
#!/bin/bash 
name="Alice" 
echo "Hello, $name!" 
 

Output: 

Hello, Alice! 
 

Here, we assign the value “Alice“ to the variable $name and print it using echo. 

Printing without a new Line (-n option) 

bash 
#!/bin/bash 
echo -n "Enter your name: " 
read name 
echo "Hello, $name!" 
 

The -n flag prevents echo from adding a new line, so the cursor remains on the same line. 

Using escape sequences (-e option) 

bash 
#!/bin/bash 
echo -e "Hello,\nWelcome to Bash Scripting!" 
 

Output: 

css 

Hello, 
Welcome to Bash Scripting! 
 

The -e option enables escape sequences, such as \n (new line) and \t (tab). 

2. ls – List directory contents 

The ls command lists the files and directories inside a folder. 

Basic usage: 

bash 
ls 
 

Output: 

nginx 
Documents Downloads  Pictures  Music 
 

This lists all the files and directories in the current working directory. 

Listing hidden files (-a option) 

bash 
ls -a 
 

Output: 

.  ..  .bashrc . profile  Documents  Downloads 
 

The -a flag displays hidden files (files that start with a .). 

Listing files in a long format (-l option) 

bash 
ls -l 
 

Output: 

sql 
drwxr-xr-x  2 user user 4096 Mar 10 14:45 Documents 
-rw-r--r--  1 user user 1234 Mar 09 10:12 file.txt 
 

The -l option provides detailed information such as file permissions, owner, size and modification date. 

3. cd – Change directories 

The cd command allows you to navigate between directories. 

Basic usage: 

bash 
cd Documents 
 

This moves you into the document’s directory. 

Going up one level 

bash 
cd .. 
 

Moves to the parent directory. 

Navigating to the home directory (~) 

bash 
cd ~ 
 

Moves to the home directory of the logged-in user. 

Navigating Using Absolute and Relative Paths 

bash 
cd /home/user/Documents 
 

Moves to the Documents directory using an absolute path. 

bash 
cd Downloads/Files 
 

Moves to the files directory inside downloads using a relative path. 

4. pwd – Show current directory 

The pwd (Print Working Directory) command displays the full path of the current directory. 

Basic usage: 

bash 
pwd 
 

Output: 

arduino 
/home/user/Documents 
 

This tells you exactly where you are in the filesystem. 

5. grep – Search for patterns in text 

The grep command is a powerful text-searching tool used to find specific words or patterns inside files. 

Basic usage: 

bash 
grep "error" log.txt 
 

This search for the word “error” inside log.txt. 

Using grep with case-insensitive search (-i) 

bash 
grep -i "error" log.txt 
 

The -i flag makes the search case-insensitive, so it will match “Error”, “ERROR” and “error”. 

Searching for whole words (-w) 

bash 
grep -w "fail" system.log 
 

This searches for the whole word “fail”, avoiding partial matches like “failure”. 

Finding lines that do NOT match (-v) 

bash 
grep -v "success" log.txt 
 

The -v flag excludes lines containing “success”. 

Searching recursively in multiple files (-r) 

bash 
grep -r "ERROR" /var/logs/ 
 

This search for “ERROR” in all files inside /var/logs/. 

6. awk – Process structured text data 

The awk command is used for processing and analyzing structured text, like CSV files, system logs and tabular data. 

Basic usage: 

bash 
awk '{print $1}' file.txt 
 

Prints the first column of each line in file.txt. 

Filtering data based on conditions 

bash 
awk '$3 > 50 {print $1, $3}' scores.txt 
 

This prints the first and third columns only for rows where the third column value is greater than 50. 

Using awk to format text output 

Bash 
awk '{print "User: " $1 ", Score: " $3}' scores.txt 
 

Adds custom text formatting: 

yaml 
User: Alice, Score: 85 
User: Bob, Score: 73 
 

Extracting data from ls -l output 

bash 
ls -l | awk '{print $9, $5}' 
 

Extracts and prints file names and sizes from the ls -l command. 

How can you automate tasks using bash?

One of the biggest advantages of bash scripting is automation. Whether it’s scheduling system updates, backing up files or managing log files, automation saves time and reduces human errors. 

Bash scripts can run commands sequentially, ensuring that tasks are executed in the correct order. You can schedule scripts to run at specific intervals, handle file transfers and even send system notifications. 

1. Using cron for scheduling 

Cron is a built-in task scheduler in Unix-based systems that allows you to run scripts automatically at predefined times. Instead of manually executing scripts, cron does it for you! 

1.1 Setting up a cron job 

To schedule a script, open the crontab file using: 

bash 
crontab -e 
 

This opens the cron editor, where you can define tasks. 

1.2 Cron job syntax 

A typical cron job format: 

sql 
Minute  Hour  Day  Month  Weekday  Command 
 

Symbol	Meaning	Example
*	Any value	* * * * * runs every minute
*/n	Every n units	*/5 * * * * runs every 5 minutes
0 12 * * *	Specific time	Runs at 12:00 PM every day

For example: Running a script daily at midnight 

If you want to backup files at midnight every day, add this to the crontab: 

bash 
0 0 * * * /home/user/backup.sh 
 

This script runs at exactly 12:00 AM. 

1.3 Viewing scheduled cron jobs 

To list all cron jobs, run: 

bash 
crontab -l 
 

1.4 Removing a cron job 

To delete all cron jobs: 

bash 
crontab -r 
 

Cron is a powerful tool for automating repetitive tasks with zero manual intervention. 

Using cron for scheduling 

Cron jobs execute scripts at scheduled times. 

bash 
crontab -e 
0 5 * * * /home/user/backup.sh 
 

Runs backup.sh daily at 5 AM. 

2. Automating file backups 

Backups are crucial for data security. Manually copying files every day is inefficient—bash can automate this process. 

2.1 Basic backup script 

bash 
#!/bin/bash 
tar -czf /home/user/backup_$(date +%F).tar.gz /home/user/Documents 
echo "Backup completed!" 

This script: 

• Creates a compressed backup file (tar.gz). 
• Uses the current date in the filename (backup_YYYY-MM-DD.tar.gz). 
• Targets the /home/user/Documents folder. 

3. Automating backups with cron 

Schedule backups every Sunday at 2 AM: 

bash 
0 2 * * 0 /home/user/backup_script.sh 

Now, backups run automatically every week!  

3.1 Writing reusable scripts 

Reusable scripts save time and improve efficiency. Instead of rewriting similar scripts, create one script that accepts parameters and can be used in multiple situations. 

For example: A generalized backup script 

bash 
#!/bin/bash 
backup() { 
    tar -czf "$1_$(date +%F).tar.gz" "$1" 
    echo "Backup of $1 completed!" 
} 
 backup /home/user/Documents 
backup /var/logs 
 

Now, you can call backup <directory> anytime to back up any folder. 

3.2 Using arguments in scripts 

You can pass arguments to scripts to make them more flexible. 

bash 
#!/bin/bash 
echo "Hello, $1! Welcome to Bash scripting." 
 

Run it with: 

bash 
./script.sh Alice 
 

Output: 

css 
Hello, Alice! Welcome to Bash scripting. 

Bash scripting best practices 

By designing scripts with parameters and functions, you make them more flexible and reusable. 

Writing efficient and maintainable bash scripts requires more than just getting them to run. By following best practices, you ensure that your scripts are readable, secure and error-free. Whether you’re automating tasks, managing files or scheduling processes, a well-structured script saves time and prevents issues. 

Writing readable code 

Readable scripts are easier to understand, modify and debug. Always use clear variable names that describe their purpose rather than generic names. Proper indentation and formatting help organize script logic, making it easy to follow. Adding comments is essential, especially for complex sections, so that others (or even you in the future) can quickly understand the script’s purpose. 

A well-structured script improves collaboration, ensures easy maintenance and reduces the risk of misinterpretation. 

Handling errors gracefully 

Bash scripts should be designed to handle errors properly rather than failing silently. This means checking for potential failures and providing meaningful error messages when something goes wrong. Implementing proper error handling prevents unexpected issues from disrupting processes. 

Using mechanisms like exit codes and conditional checks, you can ensure that the script stops or takes corrective action when an error occurs. This is especially important when dealing with system files, user input or automated tasks that run unattended. 

Debugging bash scripts 

Even well-written scripts may not work perfectly on the first try. Debugging helps identify issues and improve script reliability. Bash provides built-in debugging tools that allow you to trace command execution and pinpoint problems. 

Using debugging flags and log messages, you can analyze how a script runs and detect errors before they cause major failures. Organizing scripts with functions and structured logic also makes debugging easier by isolating problems in specific sections rather than searching through an entire script. 

Security considerations 

Security is crucial in bash scripting, especially when scripts handle user input, system processes or sensitive data. Avoid storing passwords or sensitive information in plain text. Instead, use environment variables or secure credential management tools to keep data protected. 

Also read: Security Advice: Best Practices for a Strong Password Policy 

User input should always be validated to prevent security vulnerabilities like command injection. Restricting file permissions ensures that only authorized users can execute or modify scripts, preventing unintended access or manipulation. 

Hosting your bash scripts with VPS 

If you’re looking for a reliable and secure way to run your bash scripts, hosting them on a VPS (Virtual Private Server) is a great choice. A VPS gives you full control over your server environment, allowing you to automate tasks, schedule scripts and manage your system remotely without interruptions. 

Pros & cons of using VPS for bash scripting 

Pros	Cons
24/7 availability ensures scripts run even when your local system is off.	Requires additional cost for hosting.
Remote execution allows you to automate tasks from anywhere.	Needs some technical knowledge to set up and maintain.
Improved security with controlled access and encryption.	Can have performance limitations depending on the VPS plan.
Scalable resources allow handling larger tasks.	Potential downtime due to maintenance or network issues.

That’s why hosting your scripts with Bluehost VPS is a game-changer. With a dedicated, always-on environment, you can automate deployments, schedule cron jobs and execute complex scripts effortlessly, all while ensuring top-notch security and scalability. 

Why use a Bluehost VPS for bash scripting? 

At Bluehost, we provide a powerful hosting environment that makes running bash scripts easy and seamless. Hosting your scripts on our VPS comes with several key benefits: 

24/7 availability 

Unlike a local machine, a VPS runs 24/7, ensuring that your bash scripts execute without requiring your computer to be on. This is ideal for scheduled backups, monitoring and automated tasks. 

Remote execution & automation 

With a VPS, you can run scripts from anywhere, making it perfect for: 

• Automating deployments for websites or applications. 
• Running scheduled cron jobs for backups and maintenance. 
• Monitoring system performance and logging important metrics. 

Better security & data protection 

Hosting your scripts on a VPS enhances security in multiple ways: 

• Encryption: Use SSL/TLS for secure communication and protect sensitive data. 
• Permission control: Apply chmod 700 to restrict script access to the owner. 
• Firewall & access control: Configure UFW (ufw allow ssh) to limit access.  

For example: –  

chmod 700 my_secure_script.sh # Only the owner can execute 
ufw allow from 192.168.1.100 to any port 22 # Restrict SSH to a specific IP 

Improved performance & scalability 

If your scripts process large amounts of data, a VPS provides better hardware resources than a personal computer, ensuring faster execution. You can also scale your VPS resources as needed. 

Power your bash scripts with a hosting environment designed for efficiency, automation and security. With Bluehost VPS, you get the performance and scalability needed to handle complex scripts without interruptions. 

How to set up bash scripting on a Bluehost VPS 

Getting started with bash scripting on a Bluehost VPS is quick and simple. Follow these steps to set up and automate your scripts in just a few minutes 

Step 1: Purchase a Bluehost VPS plan 

• Choose a VPS hosting plan based on your requirements. 
• Set up your server with a Linux-based OS (Ubuntu, CentOS or Debian). 

Step 2: Access your VPS via SSH 

• Use an SSH client (like PuTTY or the terminal) to connect: ssh user@your-vps-ip-address  
• This gives you remote access to execute bash scripts from anywhere. 

Step 3: Upload your bash scripts to the VPS 

• Use scp (Secure Copy Protocol) to transfer scripts from your local machine: scp script.sh user@your-vps-ip:/home/user/ 
• Ensure scripts have execution permissions using: chmod +x script.sh 

Step 4: Set up scheduled script execution with cron 

• Automate scripts by adding them to the crontab for scheduled execution. 

Step 5: Monitor your scripts and logs 

• Store logs to track script execution: ./script.sh >> logs.txt 2>&1 
• Regularly check logs to ensure your scripts are running smoothly. 

By hosting your scripts on a Bluehost VPS, you gain reliability, security and automation, allowing your tasks to run seamlessly without manual intervention. 

Final thoughts 

Bash scripting is one of the most powerful tools for automating tasks, managing files and improving system efficiency. Whether you’re a beginner learning the basics or an experienced developer looking to optimize workflows, bash scripting can help you save time and effort. 

By following best practices, such as writing readable, secure and error-free scripts, you ensure that your scripts are efficient and maintainable. Additionally, hosting your bash scripts on a VPS server with Bluehost allows for reliable, scalable and 24/7 execution, making automation even more powerful. 

Make your scripts unstoppable. Get started with Bluehost today! 

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