The golden rule of DevOps: if you do something more than twice, automate it. Bash scripting is your first automation superpower.

Your first script

Create a file hello.sh:

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

The first line (#!/bin/bash) is the shebang, it tells the system to run this with Bash. Then make it executable and run it:

chmod +x hello.sh
./hello.sh

Variables

#!/bin/bash
name="DevOps Adda"
echo "Welcome to $name"

# Capture command output
today=$(date +%F)
echo "Today is $today"

Use quotes around variables ("$name") to avoid surprises with spaces.

Taking input

#!/bin/bash
read -p "What's your name? " user
echo "Hi $user, let's automate something!"

Conditionals

#!/bin/bash
if [ -f "/etc/passwd" ]; then
    echo "The file exists."
else
    echo "Not found."
fi

Common test flags: -f (file exists), -d (directory exists), -z (string empty), -eq/-ne/-gt/-lt (number comparisons).

Loops

#!/bin/bash
# Loop over a list
for service in nginx docker ssh; do
    echo "Checking $service..."
done

# Loop over files
for file in *.log; do
    echo "Found log: $file"
done

# While loop
count=1
while [ $count -le 3 ]; do
    echo "Attempt $count"
    count=$((count + 1))
done

Functions

#!/bin/bash
greet() {
    echo "Hello, $1!"   # $1 is the first argument
}

greet "World"
greet "DevOps"

A practical example: a backup script

#!/bin/bash
SOURCE="/home/user/project"
DEST="/backups"
STAMP=$(date +%Y%m%d-%H%M%S)

mkdir -p "$DEST"
tar -czf "$DEST/backup-$STAMP.tar.gz" "$SOURCE"

echo "Backup created: $DEST/backup-$STAMP.tar.gz"

Scheduling with cron

Run scripts automatically on a schedule:

crontab -e

Add a line (this runs the backup every day at 2 AM):

0 2 * * * /home/user/backup.sh

The five fields are: minute hour day-of-month month day-of-week. Use crontab.guru to decode schedules.

Good habits

  • Add set -e near the top so the script stops on the first error.
  • Use set -u to catch undefined variables.
  • Comment your scripts, future-you will thank you.
#!/bin/bash
set -euo pipefail

Practice challenge 🏋️

Write a script that checks if a website is up:

#!/bin/bash
read -p "Enter a URL: " url
if curl -s --head "$url" | grep "200 OK" > /dev/null; then
    echo "✅ $url is up!"
else
    echo "❌ $url seems down."
fi

What’s next?

You can automate tasks now. Time to learn the technology that changed how we ship software: containers.

👉 Next up: Docker for Absolute Beginners