Lecture 2: Directories and Exception Handling

import os # Get current working directory current_dir = os.getcwd() print(f"Current directory: {current_dir}") # List directory contents print("\nDirectory contents:") for item in os.listdir('.'): print(f"- {item}") # Create a new directory os.mkdir('new_directory') # Create directories recursively os.makedirs('path/to/new/directory', exist_ok=True) # Remove a directory (must be empty) os.rmdir('new_directory') # Remove directory tree (use with caution!) import shutil shutil.rmtree('path/to/remove', ignore_errors=True)

import os import shutil # Check if path exists path = 'example.txt' if os.path.exists(path): print(f"{path} exists!") # Check if path is a file or directory if os.path.isfile(path): print(f"{path} is a file") elif os.path.isdir(path): print(f"{path} is a directory") # Get file size size = os.path.getsize(path) print(f"File size: {size} bytes") # Get file modification time mod_time = os.path.getmtime(path) from datetime import datetime print(f"Last modified: {datetime.fromtimestamp(mod_time)}") # Copy files shutil.copy('source.txt', 'destination.txt') # Move/rename files os.rename('old_name.txt', 'new_name.txt') # Delete a file os.remove('file_to_delete.txt')

import os def list_files(startpath): for root, dirs, files in os.walk(startpath): level = root.replace(startpath, '').count(os.sep) indent = ' ' * 4 * level print(f"{indent}{os.path.basename(root)}/") subindent = ' ' * 4 * (level + 1) for f in files: print(f"{subindent}{f}") # Example usage list_files('.') # Find all .py files in a directory tree def find_py_files(directory): py_files = [] for root, dirs, files in os.walk(directory): for file in files: if file.endswith('.py'): py_files.append(os.path.join(root, file)) return py_files # Count lines of code in all Python files def count_lines(directory): total_lines = 0 for py_file in find_py_files(directory): with open(py_file, 'r', encoding='utf-8') as f: lines = f.readlines() total_lines += len(lines) print(f"{py_file}: {len(lines)} lines") print(f"\nTotal lines of Python code: {total_lines}")

# View the built-in exception hierarchy def print_exception_hierarchy(exception_class, indent=0): print(' ' * indent + exception_class.__name__) for subclass in exception_class.__subclasses__(): print_exception_hierarchy(subclass, indent + 4) # Print the hierarchy starting from BaseException print_exception_hierarchy(BaseException)

import os import shutil from datetime import datetime, timedelta def cleanup_directory(directory, days_old=30, extensions=None, dry_run=False): """ Remove files older than specified days with given extensions. Args: directory (str): Directory to clean up days_old (int): Remove files older than this many days extensions (list): List of file extensions to consider (None means all) dry_run (bool): If True, only show what would be deleted """ if not os.path.exists(directory): print(f"Error: Directory '{directory}' does not exist.") return if not os.path.isdir(directory): print(f"Error: '{directory}' is not a directory.") return cutoff_time = datetime.now() - timedelta(days=days_old) total_size = 0 removed_count = 0 print(f"Cleaning up directory: {directory}") print(f"Removing files older than: {cutoff_time}") if extensions: print(f"File extensions: {', '.join(extensions) if extensions else 'All'}") print("-" * 50) for root, dirs, files in os.walk(directory, topdown=False): for file in files: if extensions and not any(file.lower().endswith(ext.lower()) for ext in extensions): continue file_path = os.path.join(root, file) try: mod_time = datetime.fromtimestamp(os.path.getmtime(file_path)) if mod_time < cutoff_time: file_size = os.path.getsize(file_path) print(f"Removing: {file_path} (Last modified: {mod_time}, Size: {file_size} bytes)") if not dry_run: try: if os.path.isfile(file_path): os.remove(file_path) elif os.path.isdir(file_path): shutil.rmtree(file_path) removed_count += 1 total_size += file_size except Exception as e: print(f" Error removing {file_path}: {e}") except Exception as e: print(f" Error processing {file_path}: {e}") print("-" * 50) print(f"Total files removed: {removed_count}") print(f"Total space freed: {total_size / (1024*1024):.2f} MB") # Example usage if __name__ == "__main__": import argparse parser = argparse.ArgumentParser(description='Clean up old files in a directory.') parser.add_argument('directory', help='Directory to clean up') parser.add_argument('--days', type=int, default=30, help='Remove files older than this many days (default: 30)') parser.add_argument('--ext', nargs='+', help='File extensions to include (e.g., .tmp .log)') parser.add_argument('--dry-run', action='store_true', help='Show what would be deleted without actually deleting') args = parser.parse_args() cleanup_directory( args.directory, days_old=args.days, extensions=args.ext, dry_run=args.dry_run )