📝 Bash Scripting Basics Every DevOps Engineer Should Know

If you’re learning DevOps, Linux, or Cloud Computing, Bash scripting is one of the most valuable skills you can develop.

Up until now, you’ve probably been running Linux commands one by one in the terminal. But in real-world DevOps, repeating the same commands manually isn’t efficient. Instead, we automate those tasks using shell scripts.

Whether you’re deploying applications, monitoring servers, creating backups, or scheduling maintenance jobs, Bash scripting is often the first step toward automation.

In this article, I’ll cover:

✅ Why Bash scripting matters
✅ Terminal text editors (Nano & Vim)
✅ Creating your first Bash script
✅ Variables and special variables
✅ Conditionals (if, else)
✅ Loops (for, while)
✅ Functions
✅ Automating tasks with Cron

Let’s get started.

Why Bash Scripting Matters

Imagine typing the same five commands every day to:

• Deploy an application
• Back up a database
• Restart a service
• Clean old log files

Instead of repeating these commands manually, you can place them inside a script and execute them with a single command.

That’s automation.

In fact, Bash scripting is the foundation of many DevOps tools. Before Jenkins pipelines, Ansible playbooks, or Terraform modules execute tasks, they’re often running shell commands behind the scenes.

Learning Bash means learning how automation actually works.

Terminal Text Editors

When working on remote Linux servers through SSH, you usually won’t have a graphical editor like VS Code.

Instead, you’ll use terminal-based editors.

The two most common are Nano and Vim.

Nano

Nano is beginner-friendly and easy to use.

Open a file:

nano script.sh

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Useful shortcuts:

Shortcut Action Ctrl + O Save Ctrl + X Exit Ctrl + K Cut a line Ctrl + U Paste Ctrl + W Search

Nano displays these shortcuts at the bottom of the screen, making it easy for beginners.

Vim

Vim is one of the most powerful text editors available on Linux.

Open a file:

vim script.sh

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Unlike Nano, Vim uses different modes.

Mode Purpose Normal Execute commands Insert Type text Command Save, quit, search

Essential Vim commands:

i      → Enter Insert mode
Esc    → Return to Normal mode
:w     → Save
:q     → Quit
:wq    → Save and Quit
:q!    → Quit without saving
dd     → Delete current line
/text  → Search for text

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While Vim has a learning curve, it’s installed on almost every Linux system, making it a valuable tool to know.

Creating Your First Bash Script

A Bash script is simply a text file containing Linux commands.

Every script should begin with a shebang.

#!/bin/bash

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The shebang tells Linux which interpreter should execute the script.

Example:

#!/bin/bash

echo "Hello DevOps!"

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Save the file as:

hello.sh

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Make it executable:

chmod +x hello.sh

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Run it:

./hello.sh

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You can also execute it without making it executable:

bash hello.sh

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Working with Variables

Variables store values that can be reused throughout a script.

Example:

#!/bin/bash

name="DevOps Engineer"
count=5

echo "Hello, $name"
echo "Count: $count"

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Important Rules

• No spaces around =
• Use $ when accessing a variable
• Wrap variables inside double quotes

Correct:

name="John"
echo "$name"

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Incorrect:

name = "John"

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Command Substitution

Store command output inside a variable.

Example:

current_date=$(date)

echo "$current_date"

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Another example:

file_count=$(ls | wc -l)

echo "$file_count files found."

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This technique is commonly used in automation scripts.

Special Variables

Bash provides several built-in variables.

Variable Purpose $0 Script name $1 First argument $2 Second argument $# Number of arguments $? Exit status of previous command

Example:

./deploy.sh production

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Inside the script:

echo "$1"

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Output:

production

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Using Conditionals

Conditionals allow scripts to make decisions.

Example:

disk_usage=85

if [ "$disk_usage" -gt 80 ]; then
    echo "Disk usage is high!"
else
    echo "Disk usage is healthy."
fi

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Common Comparison Operators

Operator Meaning -eq Equal -ne Not equal -gt Greater than -lt Less than -ge Greater than or equal -le Less than or equal == String equality != String inequality -f File exists -d Directory exists

Checking Whether a File Exists

if [ -f "app.log" ]; then
    echo "Log file found."
else
    echo "Log file missing."
fi

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This is a common pattern in deployment and monitoring scripts.

Using Loops

Loops execute commands repeatedly.

For Loop

for server in web1 web2 web3
do
    echo "Deploying to $server"
done

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Loop through files:

for file in *.log
do
    echo "$file"
done

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Loop over numbers:

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

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While Loop

count=1

while [ "$count" -le 5 ]
do
    echo "$count"
    count=$((count+1))
done

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Real Example: Retry Until Success

attempt=0

while [ "$attempt" -lt 5 ]
do
    if curl -sf http://localhost:8080/health
    then
        echo "Service is running."
        break
    fi

    echo "Retrying..."

    attempt=$((attempt+1))

    sleep 5
done

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This pattern is widely used in deployment scripts.

Creating Functions

Functions help organize larger scripts.

Example:

log_message() {
    local message=$1
    echo "$(date): $message"
}

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Call the function:

log_message "Deployment started"

log_message "Deployment completed"

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Using functions makes scripts easier to read and maintain.

Automating Tasks with Cron

Automation becomes even more powerful when scripts run automatically.

Linux provides cron for scheduling tasks.

Edit your cron jobs:

crontab -e

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Cron format:

* * * * * command
│ │ │ │ │
│ │ │ │ └── Day of Week
│ │ │ └──── Month
│ │ └────── Day of Month
│ └──────── Hour
└────────── Minute

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Common Cron Examples

Run every day at 2:30 AM:

30 2 * * * /home/user/backup.sh

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Run every hour:

0 * * * * /home/user/health-check.sh

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Run every Monday at 9 AM:

0 9 * * 1 /home/user/report.sh

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Run every five minutes:

*/5 * * * * /home/user/monitor.sh

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Logging Cron Output

Always redirect cron output to a log file.

30 2 * * * /home/user/backup.sh >> /home/user/backup.log 2>&1

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This captures both:

• Standard output
• Error messages

Making troubleshooting much easier.

Best Practices for Bash Scripts

• Start every script with #!/bin/bash
• Use meaningful variable names
• Always quote variables
• Use functions for reusable logic
• Test scripts before running them in production
• Use absolute paths in cron jobs
• Log script output for easier debugging
• Add comments to improve readability

Quick Command Reference

Command Purpose nano file.sh Open file in Nano vim file.sh Open file in Vim chmod +x file.sh Make script executable ./file.sh Run script bash file.sh Execute with Bash crontab -e Edit cron jobs date Current date and time $(command) Command substitution $? Previous command exit status $# Number of arguments

Final Thoughts

Bash scripting is where Linux commands become automation.

By learning how to write scripts, use variables, create loops, organize code with functions, and schedule jobs with Cron, you’re building the foundation for more advanced DevOps tools like Jenkins, Ansible, Terraform, and Kubernetes.

These concepts may seem simple now, but they’re used every day in real production environments.

If you have any Bash scripting tips or favorite automation tricks, feel free to share them in the comments.

Happy Learning! 🐧🚀