CPU Usage Daemon

• CPU Monitoring Daemon
  • Features
  • Prerequisites
  • Installation
  • Usage
  • Configuration
  • Technical Details
    • Process Management
    • CPU Monitoring
    • Error Handling
  • Logging
  • Error Codes
  • Contributing
  • License
  • Acknowledgments

A lightweight system daemon that monitors CPU usage in real-time and logs the metrics to syslog. This daemon is designed to run in the background and provide continuous CPU utilization statistics with minimal system overhead.

Features

• Runs as a proper Unix daemon process
• Real-time CPU usage monitoring
• Secure process isolation with double-forking
• Configurable PID file location
• Detailed syslog integration
• Clean process management and termination
• Automated build and run script

Prerequisites

• Linux-based operating system
• G++ compiler
• Root privileges (for daemon operations)
• System logger (syslog) configured

Installation

1. Clone the repository:

git clone https://github.com/stackanthony/cpu-usage-daemon.git
cd cpu-usage-daemon

2. Compile the project:

g++ -o mydaemon main.cpp utils.cpp

Usage

The project includes a convenient shell script to handle the building, running, and monitoring of the daemon.

1. Run the daemon:

./launch.sh

2. The script will:

   • Compile the source code
   • Prompt for a PID file location
   • Launch the daemon process
   • Start monitoring the syslog output

3. Monitor the daemon's output:

   • CPU usage statistics will be logged to syslog
   • The script automatically filters and displays relevant log entries

4. To stop the daemon:

   • Press Ctrl+C in the terminal running the script
   • The cleanup process will automatically terminate the daemon and remove the PID file

Configuration

The daemon supports the following configurations:

• PID File Location: Specified at runtime
• Polling Rate: Default is 1 second (can be modified in main.cpp)
• Working Directory: Automatically set to root (/)
• Log Level: Uses syslog with INFO level for metrics and ERR level for errors

Technical Details

Process Management

• Implements the double-fork technique for proper daemonization
• Creates a new session using setsid()
• Manages standard file descriptors
• Handles process isolation and zombie prevention

CPU Monitoring

• Reads CPU statistics from /proc/stat
• Calculates CPU usage percentage across all cores
• Tracks user, system, idle, I/O wait, and interrupt time
• Updates metrics at configurable intervals

Error Handling

• Comprehensive error checking and reporting
• Secure file operations
• Proper resource cleanup on termination
• Detailed error logging through syslog

Logging

The daemon logs its activity to syslog with the following format:

• CPU usage metrics: LOG_INFO level
• Operational messages: LOG_NOTICE level
• Error conditions: LOG_ERR level

Monitor the logs in real-time:

tail -f /var/log/syslog | grep --line-buffered mydaemon

Error Codes

The daemon may exit with the following status codes:

• 0: Normal termination
• 1: Configuration error
• Other non-zero values: System-specific error codes

Contributing

1. Fork the repository
2. Create a feature branch
3. Commit your changes
4. Push to the branch
5. Create a Pull Request

License

[MIT License]

Acknowledgments

• Based on standard Unix daemon design patterns
• Utilizes Linux process management best practices