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Day 05 Integration & Deployment

Shell Scripting

Write bash scripts with variables, conditionals, loops, and functions. Automate backups and deployments.

~1 hour Hands-on Precision AI Academy

Today’s Objective

Write bash scripts with variables, conditionals, loops, and functions. Automate backups and deployments.

Shell Scripting is one of the most important topics in Linux in 5 Days. This lesson builds the foundation you need before moving to more advanced concepts — take time with each example and run the code yourself.

Bash Script Basics

script.sh
SCRIPT.SH
#!/bin/bash
# The shebang tells the OS to use bash
set -euo pipefail  # exit on error, undefined var, pipe failure

# Variables (no spaces around =)
NAME="World"
echo "Hello, $NAME!"
echo "Script: $0, Arg1: $1, All args: $@"

# Command substitution
TODAY=$(date +%Y-%m-%d)
FILE_COUNT=$(ls | wc -l)
echo "Today: $TODAY, Files: $FILE_COUNT"
Conditionals and Loops
CONDITIONALS AND LOOPS
# if/elif/else
if [ -f "file.txt" ]; then echo "File exists"
elif [ -d "mydir" ]; then echo "Directory exists"
else echo "Neither exists"
fi

# for loop
for file in *.txt; do echo "Processing: $file"
done

# while loop
COUNT=0
while [ $COUNT -lt 5 ]; do echo "Count: $COUNT" COUNT=$((COUNT + 1))
done
Functions and Error Handling
FUNCTIONS AND ERROR HANDLING
#!/bin/bash
set -euo pipefail

# Function
backup() { local SRC=$1 local DST=$2 local DATE=$(date +%Y%m%d_%H%M%S) cp -r "$SRC" "${DST}_${DATE}" echo "Backed up $SRC to ${DST}_${DATE}"
}

# Error handling
if ! command -v docker &>/dev/null; then echo "Error: Docker not installed" >&2 exit 1
fi

# Run backup
backup /var/www/html /backup/html
Cron: Schedule Scripts
CRON: SCHEDULE SCRIPTS
# Edit crontab
crontab -e

# Format: minute hour day month weekday command
# Run backup every day at 2am
0 2 * * * /home/bo/scripts/backup.sh >> /var/log/backup.log 2>&1

# Every 15 minutes
*/15 * * * * /home/bo/scripts/check-disk.sh

# Every Monday at 9am
0 9 * * 1 /home/bo/scripts/weekly-report.sh
📝 Day 5 Exercise
Write a Deployment Script
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Supporting Resources

Go deeper with these references.

Linux Die
Linux Command Reference Comprehensive reference for Linux commands, flags, and shell built-ins.
→
DigitalOcean
Linux Basics Tutorial Series Step-by-step tutorials for new Linux users with practical examples.
→
GitHub
Bash Guide Community bash guide covering scripting, arrays, functions, and error handling.
→

Day 5 Checkpoint

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