Hashnode Blog: Automated System Monitoring with a Bash Script

Introduction

Monitoring system health is crucial for administrators and developers working with Linux systems. In this blog, I’ll walk through a Bash script I created to automatically log system information like uptime, disk space, and memory usage at regular intervals. This project simplifies system diagnostics by generating periodic reports in a structured format.

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Project Overview

The script continuously logs critical system metrics into a System_info.txt file at user-defined intervals. It provides a lightweight alternative to complex monitoring tools and demonstrates how Bash scripting can automate repetitive tasks.

Key Features:

• Automated logging of uptime, disk space, and memory usage.

• Customizable intervals (default: 3 seconds).

• Timestamped reports for trend analysis.

• Error-resistant file appending.

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Code Breakdown

#!/bin/bash

# This script logs system information at defined intervals
REPORT_FILE="System_info.txt"
Sleep_Interval=3

while true;
do
    Timestamp=$(date)    

    # Append section headers to the report
    echo "--------System Info Report ($Timestamp)--------" >> "$REPORT_FILE"

    # Log system uptime
    echo "Uptime:" >> "$REPORT_FILE"
    uptime >> "$REPORT_FILE"

    # Log disk space (root partition)
    echo "Free Disk Space (root):" >> "$REPORT_FILE"
    df -h >> "$REPORT_FILE"

    # Log memory usage
    echo "Free Memory:" >> "$REPORT_FILE"
    free -m | head -2 >> "$REPORT_FILE"

    echo "-------System Info Report Ended ($Timestamp)--------" >> "$REPORT_FILE"

    # User feedback
    echo ".....Report Saved to $REPORT_FILE | Next check in $Sleep_Interval seconds....."

    sleep "$Sleep_Interval"
done

How It Works:

1. Loop Structure:

   • Uses an infinite while loop to run continuously.

   • Sleep_Interval controls the delay between checks (default: 3 seconds)[4].

2. Metric Collection:

   • Uptime: Uses uptime to show system runtime and load averages[2][3].

   • Disk Space: df -h displays human-readable storage metrics for all mounted partitions[2][4].

   • Memory Usage: free -m shows RAM usage in megabytes, filtered to display only essential lines[5].

3. Output Formatting:

   • Timestamps each report section for easy tracking.

   • Uses >> to append data without overwriting previous logs.

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Applications

• Long-term Monitoring: Run overnight to identify resource spikes.

• Troubleshooting: Capture system states before/after critical operations.

• Server Maintenance: Monitor shared servers without GUI tools[3][4].

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Key Takeaways

Building this script helped me:

1. Master loop structures in Bash scripting.

2. Learn to combine CLI tools (df, free, uptime) for system diagnostics[2][5].

3. Implement persistent logging with file appending.

4. Create user-friendly status updates during script execution.

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Optimization Ideas

1. Alert System: Add thresholds to trigger warnings (e.g., disk >90% full)[3][4].

2. HTML Reports: Format output for web viewing using sed/awk.

3. Email Integration: Send logs periodically via mail command.

4. Process Monitoring: Include top CPU/memory consumers using ps[5].

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Conclusion

This project demonstrates how simple scripts can automate system monitoring tasks effectively. For developers and sysadmins, mastering such scripts reduces dependency on third-party tools while improving Linux command-line proficiency.

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