🛠️ Linux Automation Toolkit

Bash scripting • Cron jobs • Git workflow • Docker containerization
Part of my CompTIA Linux+ XK0-005 hands-on study path.

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✅ Feature-to-Skill Map

Feature	What it Proves
Bash script for disk alerts	Able to write and execute shell scripts to monitor system usage
Cron job automation	Knows how to schedule repetitive tasks using crontab
Docker container execution	Understands script containerization and basic Dockerfile syntax
Git version control	Proficient in Git commit flow and history cleanup (rebase, squash)
Markdown documentation	Can write clear, structured technical documentation in README.md
Screenshot validation	Proves command-line output through real-world terminal screenshots

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📂 Folder Structure

linux-automation-toolkit/
├── scripts/
│   └── disk_alert.sh          # disk usage monitoring script
├── cron/
│   └── daily-job.txt          # crontab entry (runs 08:00 daily)
├── docker/
│   ├── Dockerfile             # container build instructions
│   └── disk_alert.sh          # script copy used in the image
├── docs/
│   ├── bash-basics.md         # quick Bash recap
│   └── version-control-notes.md
├── screenshots/               # proof-of-work images
│   ├── 01-disk-alert-script-nano.png
│   ├── 02-disk-alert-script-execution.png
│   ├── 03-disk-alert-log-output.png
│   ├── 04-cron-disk-alert-entry.png
│   └── 05-docker-run-disk-alert.png
└── README.md

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📜 disk_alert.sh (Bash Script)

Monitors / disk usage and appends a status line to /var/log/disk_alert.log.

#!/bin/bash
LOGFILE="/var/log/disk_alert.log"
THRESHOLD=80

USAGE=$(df / | tail -1 | awk '{print $5}' | tr -d '%')

if [ "$USAGE" -ge "$THRESHOLD" ]; then
    MESSAGE="$(date): WARNING – Disk usage is at ${USAGE}%"
else
    MESSAGE="$(date): OK – Disk usage is at ${USAGE}%"
fi

echo "$MESSAGE" >> "$LOGFILE"

Key Bash concepts: shebang, variables, command substitution, awk, comparison operators, redirection.

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📅 Cron Job Automation

Step	Command	Purpose
1️⃣	sudo crontab -e	Edit root crontab
2️⃣	Add line → 0 8 * * * /Users/carlossemeao/linux-automation-toolkit/scripts/disk_alert.sh	Run script daily @ 08:00
3️⃣	sudo crontab -l	Confirm job installed

📸 Screenshot:

Log sample:

Wed 11 Jun 2025 08:00:01 BST: OK – Disk usage is at 9%

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🐳 Docker Container Execution

A minimal image runs the script in isolation.

docker/Dockerfile

FROM debian:bullseye-slim
RUN apt-get update && apt-get install -y bash coreutils && rm -rf /var/lib/apt/lists/*
RUN mkdir -p /var/log
COPY disk_alert.sh /usr/local/bin/disk_alert.sh
RUN chmod +x /usr/local/bin/disk_alert.sh
CMD ["/usr/local/bin/disk_alert.sh"]

🔧 Build & Run

cd linux-automation-toolkit
docker build -t disk_alert.img ./docker
docker run --rm disk_alert.img

📸 Screenshot:

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📸 Development Screenshots

#	Description	Image
1	Script written in nano
2	Manual execution test
3	Log output on host
4	Cron job entry
5	Docker container output

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🧠 Lessons Learned

• Bash: variables, loops, conditions, logging
• Cron: scheduling, redirection to log files
• Docker: Dockerfile basics, custom entrypoint, container testing
• Git: clean repo structure, meaningful commits, Markdown documentation

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🚀 How to Extend

• Parameterize the script to monitor multiple mount points.
• Add email or Slack notifications on warning.
• Use Docker volumes to persist logs outside container.
• Integrate this with Ansible for fleet-wide deployment.

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📜 License

MIT