System Monitor 🔍

A powerful Bash script for real-time system monitoring. Displays CPU, memory, disk, and network metrics with colored output and threshold alerts.

🇷🇺 Russian Version

📊 Features

• CPU Monitoring: Load average (1, 5, 15 minutes) and core utilization
• Memory Tracking: RAM usage, available memory, and utilization percentages
• Disk Space: Root partition usage with filesystem information
• Network Statistics: Interface details with RX/TX traffic monitoring
• Process Count: Total number of running processes
• Color-coded Alerts: Visual warnings for critical thresholds
• Multiple Output Modes: Interactive, brief (machine-readable), and single-run

🚀 Quick Start

# Make script executable
chmod +x system-monitor.sh

# Single system snapshot
./system-monitor.sh

# Real-time monitoring (3-second intervals)
./system-monitor.sh -i 3

# Machine-readable output for scripting
./system-monitor.sh --brief

--help

system-monitor.sh - System Monitoring Tool (CPU, Memory, Disk, Network)

Usage: ./system-monitor.sh [OPTIONS]

OPTIONS:
  -i N         Update interval in seconds (default: single output)
  --brief      Brief output (machine-readable format)
  --no-color   Disable colored output
  --version    Show version information
  --help       Show this help message

EXAMPLES:
  ./system-monitor.sh                                  # Single output
  ./system-monitor.sh -i 5                            # Update every 5 seconds
  ./system-monitor.sh --brief                       # Brief output for scripting
  ./system-monitor.sh -i 2 --no-color          # No colors, 2-second interval

EXIT CODES:
  0 - Success
  1 - Invalid arguments
  2 - Missing dependencies

📋 Usage Examples

Basic Monitoring

# Single system status check
./system-monitor.sh

# Monitor with 5-second intervals
./system-monitor.sh -i 5

# Disable colors (for logging)
./system-monitor.sh --no-color -i 2

Integration with Other Tools

# Export metrics to file
./system-monitor.sh --brief > system_status.txt

# Monitor specific metric (using grep)
./system-monitor.sh --brief | grep "cpu_load_percent"

# Continuous monitoring with tee
./system-monitor.sh -i 10 | tee system_log.txt

⚙️ Installation

Available in the AUR (Arch User Repository):

yay -S system-monitor
# or
paru -S system-monitor

Direct Download (All Distributions)

wget https://raw.githubusercontent.com/DanLinX2004X/system-monitor/main/system-monitor.sh
chmod +x system-monitor.sh
sudo mv system-monitor.sh /usr/local/bin/system-monitor

Clone Repository

git clone https://github.com/DanLinX2004X/system-monitor.git
cd system-monitor
./system-monitor.sh -i 3

🛠️ Requirements

• Bash 4.0 or newer

• Linux environment

• Basic utilities: awk, grep, free, df, ps

• Recommended: bc for advanced calculations

#Debian/Ubuntu/...
sudo apt install bc

#RedHat/Fedora/CentOS/...
sudo yum install bc

#Arch/ShefOS/Manjaro/CachyOS/...
sudo pacman -S bc

📈 Monitored Metrics

Metric	Description	Warning Threshold	Critical Threshold
CPU Load	System load average	70% per core	90% per core
Memory Usage	RAM utilization	70%	90%
Disk Usage	Root partition space	80%	90%
Network I/O	Traffic statistics	N/A	N/A
Processes	Total running processes	N/A	N/A

🎨 Output Samples

Screeens

Brief Mode

timestamp=1705587600
cpu_load_1min=0.75
cpu_load_5min=0.68
cpu_load_15min=0.55
cpu_cores=4
mem_total_gb=15.60
mem_used_gb=8.45
mem_usage_percent=54.2

🔧 Advanced Usage

Custom Thresholds

Modify the colorize() function in the script to adjust warning/critical levels:

# Current thresholds (line ~45)
echo -e "Usage: $(colorize "${MEM_PERCENT}%" 70 90)"
# Change to: $(colorize "${MEM_PERCENT}%" 60 80) for more sensitive alerts

Cron Job for Regular Monitoring

Cron is a time-based job scheduler in Linux. You can use it to run your monitor at regular intervals.

How to set up:

Open your crontab file:

crontab -e

Add a line for hourly monitoring (runs at the beginning of each hour):**

0 * * * * /full/path/to/system-monitor.sh --brief >> /var/log/system-status.log

Cron time format explained:

# ┌───────────── minute (0-59)
# │ ┌───────────── hour (0-23)
# │ │ ┌───────────── day of month (1-31)
# │ │ │ ┌───────────── month (1-12)
# │ │ │ │ ┌───────────── day of week (0-6, Sunday=0)
# │ │ │ │ │
   0 * * * * command-to-execute

Useful cron examples:

# Every day at 6:30 AM
30 6 * * * /path/to/system-monitor.sh --brief >> /var/log/monitor.log

# Every 10 minutes
*/10 * * * * /path/to/system-monitor.sh --brief >> /var/log/monitor.log

# Every Monday at 9:00 AM
0 9 * * 1 /path/to/system-monitor.sh --brief >> /var/log/monitor.log

⚠️ Important notes:

• Use --brief mode for cron (single output, not continuous)

• Specify full path to the script (/home/username/...)

• The script must be executable (chmod +x system-monitor.sh)

• Cron runs with a minimal environment - test thoroughly

🐳 Docker Container Monitoring

You can use this script to monitor resources inside Docker containers.

Prerequisites:

The container must have:

• Bash shell

• Basic Linux utilities: ps, free, df, awk, grep

Step-by-step guide:

Check if the container has Bash:

docker exec container_name which bash

Copy the script into the container:

docker cp system-monitor.sh container_name:/tmp/

Make it executable inside the container:

docker exec container_name chmod +x /tmp/system-monitor.sh

Run the monitor:

# Single snapshot
docker exec container_name /tmp/system-monitor.sh --brief

# Continuous monitoring (if supported)
docker exec container_name /tmp/system-monitor.sh -i 5

Example with a specific container:

# Monitor a PostgreSQL container
docker cp system-monitor.sh postgres-container:/tmp/
docker exec postgres-container chmod +x /tmp/system-monitor.sh
docker exec postgres-container /tmp/system-monitor.sh --brief

⚠️ Limitations:

• Minimal containers (Alpine, scratch) may not have required utilities

• Read-only containers cannot have scripts copied in

• Some system metrics may not be available in containers

🔄 *lternative: Run from host system

You can also monitor containers from the host system:

# Monitor all containers resource usage
docker stats

# Monitor specific container from host
docker exec container_name cat /proc/loadavg
docker exec container_name free -h

⚙️ CI Integration & ShellCheck Fixes

• Continuous Integration (CI): Added GitHub Actions workflow to automatically check the script on every push and pull request.
  • Syntax check (bash -n)
  • ShellCheck validation
  • Dependency verification (awk, grep, free, df, ps, bc, ip)
  • Smoke tests & basic flag tests (--help, --version, --brief)
• ShellCheck Warnings: Fixed all warnings in system-monitor.sh to ensure clean, maintainable code.
  • Quotes around variables
  • Separate declaration and assignment for local variables
  • Word splitting issues resolved

✅ CI ensures that every future change maintains script correctness and readability.

🤝 Contributing

If you'd like to suggest improvements or report issues:

📝 Easiest Way (Recommended):

1. Create an Issue on GitHub - describe your idea or problem

2. I'll implement the changes myself and credit you in the commits

💻 For Advanced Users (if familiar with Git):

1. Fork the repository (click "Fork" in the top-right corner)

2. Make changes in your own repository

3. Create a Pull Request - I'll review and merge your changes

🐛 Reporting Bugs:

In your Issue, please include:

• Your operating system (Ubuntu, CentOS, etc.)

• Bash version (bash --version)

• Error message text

• What you expected to see

💡 Improvement Ideas:

• Add CPU temperature monitoring

• Support monitoring multiple disks

• Email/Telegram notifications

• Web interface or GUI

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Don't hesitate to share ideas! Even simple suggestions are highly valuable. 🚀

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🐛 Troubleshooting

"Command not found" errors

Ensure required packages are installed:

#Debian/Ubuntu/...
sudo apt install coreutils procps util-linux

#RedHat/Fedora/CentOS/...
sudo yum install coreutils procps util-linux

#Arch/ShefOS/Manjaro/CachyOS/...
sudo pacman -S coreutils procps util-linux

"Permission denied"

Make script executable:

chmod +x system-monitor.sh

No network statistics

Script uses primary route interface. Check available interfaces:

ip link show

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📄 License

This project is licensed under the GPL v3 License - see the LICENSE file for details.

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🙏 Acknowledgments

• Inspired by classic Unix monitoring tools (top, htop, vmstat)

• Color scheme inspired by modern terminal applications

• Thanks to the Bash scripting community for best practices