Linux SysMonitor

A Bash-based Linux monitoring and log analysis tool designed to monitor system health, generate structured logs, and provide powerful log analysis capabilities.

Built as a hands-on DevOps learning project covering Linux administration, Bash scripting, troubleshooting, automation, and log management.

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Table of Contents

• Overview
• Features
• Project Structure
• Installation
• Usage
• Log Analysis
• Validation & Error Handling
• Sample Outputs
• Troubleshooting
• Technologies Used
• What I Learned
• Future Improvements

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Overview

Linux SysMonitor performs automated health checks on a Linux system and stores results in structured log files.

The accompanying analysis tool enables engineers to:

• Review health check results
• Filter logs by severity
• Identify recurring issues
• Generate summaries
• Perform time-based log analysis

This project was built to strengthen practical Linux and DevOps skills through real-world scripting and troubleshooting.

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Features

Health Monitoring

• CPU Usage Monitoring
• Memory Usage Monitoring
• Disk Usage Monitoring
• SSH Service Health Check
• Cron Service Health Check
• Network Connectivity Validation
• Open Port Inspection
• Recent System Log Collection
• Load Average Monitoring
• System Uptime Monitoring

Log Analysis

• Summary Reports
• Severity-Based Filtering
• Top Recurring Issues
• Time-Based Filtering
• Custom Log File Support
• Colored Terminal Output
• Input Validation
• Graceful Error Handling

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Architecture

+-------------------+
| health-check.sh   |
+-------------------+
          |
          v
+-------------------+
| Structured Logs   |
| logs/*.log        |
+-------------------+
          |
          v
+-------------------+
| analyse.sh        |
+-------------------+
          |
   +------+------+------+
   |             |      |
   v             v      v
Summary      Filtering  Top Issues

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Project Structure

linux-sysmonitor/
├── health-check.sh
├── analyse.sh
├── logs/
│   └── *.log
├── sample-output/
│   ├── sample-log.log
│   ├── summary.txt
│   ├── top-issues.txt
│   ├── critical.txt
│   └── since.txt
├── README.md
└── .gitignore

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Installation

Clone the Repository

git clone https://github.com/<your-username>/linux-sysmonitor.git
cd linux-sysmonitor

Make Scripts Executable

chmod +x health-check.sh
chmod +x analyse.sh

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🚦 Usage

Run a Full Health Check

./health-check.sh

This generates a timestamped log file under:

logs/

Example:

logs/2026-06-23-05-06.log

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Log Format

Generated logs follow the structure:

YYYY-MM-DD HH:MM:SS | LEVEL | MESSAGE

Example:

2026-06-23 05:06:37 | INFO | CPU usage is 10% — healthy
2026-06-23 05:06:37 | WARNING | cron is not running
2026-06-23 05:06:37 | CRITICAL | Disk usage is 96%

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Log Analysis

Generate Summary Report

./analyse.sh --summary

Example Output:

=================================
Log Summary
=================================
Total Entries: 11
INFO: 9
WARNING: 1
CRITICAL: 1
=================================

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Filter Logs by Severity

INFO Logs

./analyse.sh --level INFO

WARNING Logs

./analyse.sh --level WARNING

CRITICAL Logs

./analyse.sh --level CRITICAL

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Find Top Recurring Issues

Display the most frequent log entries:

./analyse.sh --top 5

Example:

4 CPU usage is 10% — healthy
3 Memory usage is 28% — healthy
2 cron is not running

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Time-Based Filtering

Display entries after a specific time:

./analyse.sh --since 10:30

Example:

./analyse.sh --since 14:00

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Analyse a Specific Log File

./analyse.sh --file logs/sample.log --summary

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Validation & Error Handling

Linux SysMonitor includes validation for:

• Missing arguments
• Invalid flags
• Invalid log levels
• Missing log files
• Missing logs directory
• Empty logs directory
• Invalid user input

Invalid Level

./analyse.sh --level TEST

Output:

Error: Invalid level. Use INFO, WARNING, or CRITICAL

Missing File

./analyse.sh --file missing.log

Output:

Error: File not found: missing.log

Missing Logs Directory

Error: logs directory does not exist

Empty Logs Directory

Error: No log files found

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📸 Sample Outputs

Store generated examples under:

sample-output/

Suggested files:

sample-output/
├── sample-log.log
├── summary.txt
├── top-issues.txt
├── critical.txt
├── since.txt
├── health-check.png
└── analysis-summary.png

Example screenshots:

sample-output/health-check.png
sample-output/analysis-summary.png

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Validation Commands

Generate a new log file:

./health-check.sh

Generate a summary:

./analyse.sh --summary

Display warning entries:

./analyse.sh --level WARNING

Display top recurring issues:

./analyse.sh --top 5

Display entries after a specific time:

./analyse.sh --since 12:00

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Troubleshooting

Permission Denied

chmod +x health-check.sh
chmod +x analyse.sh

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No Log Files Found

Generate a log first:

./health-check.sh

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Missing Logs Directory

mkdir -p logs

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Verify Script Quality

Install ShellCheck:

sudo apt update
sudo apt install shellcheck -y

Run analysis:

shellcheck health-check.sh
shellcheck analyse.sh

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Technologies Used

Category	Tools
Scripting	Bash
Monitoring	top, free, df
Networking	ping, ss
Text Processing	awk, grep, sort, uniq
Logging	Custom Structured Logs
Version Control	Git, GitHub
Quality Checks	ShellCheck

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What I Learned

Through this project I gained hands-on experience with:

• Linux Fundamentals
• Bash Scripting
• Shell Functions
• Conditional Logic
• Argument Parsing
• Log Management
• System Monitoring
• Process Monitoring
• Network Troubleshooting
• Text Processing with awk and grep
• Error Handling
• Defensive Scripting
• Git Branching & Pull Requests
• GitHub Project Management
• ShellCheck Best Practices

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Future Improvements

• Email Alerts
• Slack Notifications
• HTML Report Generation
• Systemd Service Integration
• Cron-Based Scheduling
• Prometheus Metrics Export
• Grafana Dashboard Integration
• Docker Packaging
• Configuration File Support
• Multi-Server Monitoring

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License

This project is intended for learning, experimentation, and portfolio demonstration purposes.

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Support

If you found this project useful, consider starring the repository and sharing feedback.

Happy scripting! 🐧