# File Size Monitor Script  

This Python snippet monitors the size of a specified file and alerts the user if the file grows beyond a specified threshold. This is useful for logging systems, large data files, or any scenario where unexpected file growth could indicate an issue.

```python
import os
import time

def monitor_file_size(file_path, max_size_mb, check_interval=60):
    """
    Monitor a file's size and alert if it exceeds a threshold.
    
    Args:
        file_path (str): Path to the file to monitor.
        max_size_mb (float): Maximum allowed file size in megabytes.
        check_interval (int): Time between checks in seconds (default: 60).
    """
    max_size_bytes = max_size_mb * 1024 * 1024  # Convert MB to bytes
    
    try:
        while True:
            if not os.path.exists(file_path):
                print(f"Error: File {file_path} does not exist.")
                break
            
            file_size = os.path.getsize(file_path)
            file_size_mb = file_size / (1024 * 1024)
            
            if file_size > max_size_bytes:
                print(f"ALERT: File {file_path} has exceeded {max_size_mb} MB. Current size: {file_size_mb:.2f} MB")
            else:
                print(f"File size OK: {file_size_mb:.2f} MB / {max_size_mb} MB")
            
            time.sleep(check_interval)
    
    except KeyboardInterrupt:
        print("\nMonitoring stopped.")
    except Exception as e:
        print(f"An error occurred: {e}")

# Example usage
if __name__ == "__main__":
    file_to_monitor = "/var/log/syslog"  # Example file (adjust as needed)
    monitor_file_size(file_to_monitor, max_size_mb=10)  # Alert if >10MB
```

## Explanation  

### What It Does  
This script:  
1. Continuously checks the size of a specified file at regular intervals.  
2. Converts the file size to megabytes (MB) for readability.  
3. Alerts the user if the file exceeds a specified threshold size.  
4. Gracefully handles interruptions (Ctrl+C) and errors.  

### Why It's Useful  
- **Log Management**: Prevents log files from growing uncontrollably.  
- **Disk Space Monitoring**: Helps avoid unexpected disk space issues.  
- **Customizable**: Adjust the threshold (`max_size_mb`) and check interval (`check_interval`) as needed.  

### How to Run It  
1. Save the script as `file_monitor.py`.  
2. Modify `file_to_monitor` and `max_size_mb` in the example usage.  
3. Run with Python:  
   ```bash
   python3 file_monitor.py
   ```  
4. Press `Ctrl+C` to stop monitoring.  

For production use, consider extending this script to send email alerts or integrate with logging systems.