How do I copy a file in Python?

To copy a file in Python, use the shutil module, which provides high-level file operations. Here are the common methods and best practices:

1. Basic File Copy

Use shutil.copy() to copy a file to a destination directory or file path.

import shutil

# Copy a file to a directory (keeps original filename)
shutil.copy("source.txt", "destination_dir/")

# Copy and rename the file
shutil.copy("source.txt", "destination_dir/new_name.txt")

Notes:

Preserves file permissions but not metadata (e.g., timestamps).
Overwrites the destination file if it exists.

2. Preserve Metadata

Use shutil.copy2() to retain file metadata (e.g., creation/modification times):

shutil.copy2("source.txt", "destination.txt")

3. Copy File Contents Only

Use shutil.copyfile() to copy content without metadata or permissions:

shutil.copyfile("source.txt", "destination.txt")

4. Handle Directories

Use shutil.copytree() to copy an entire directory tree:

shutil.copytree("source_dir", "destination_dir")

Error Handling

Wrap the operation in a try block to catch common errors:

import shutil
import FileNotFoundError

try:
    shutil.copy("source.txt", "destination.txt")
except FileNotFoundError:
    print("Source file not found.")
except PermissionError:
    print("Permission denied.")
except shutil.SameFileError:
    print("Source and destination are the same file.")

Key Notes

Overwrite Behavior: All shutil methods overwrite the destination file if it exists.
Cross-Platform: Works on Windows, macOS, and Linux.
Symbolic Links: By default, shutil.copy follows symlinks. Use copy2(src, dst, follow_symlinks=False) to copy the symlink itself.
Large Files: Uses efficient buffering for large files.

Example Workflow

import os
import shutil

source = "data/report.pdf"
destination = "backups/report_backup.pdf"

# Ensure the destination directory exists
os.makedirs(os.path.dirname(destination), exist_ok=True)

# Copy the file
try:
    shutil.copy2(source, destination)
    print(f"Copied {source} to {destination}")
except FileNotFoundError:
    print(f"Error: {source} not found.")

Alternatives

pathlib (Python 3.5+):

  from pathlib import Path
  Path("source.txt").copy_to("destination.txt")

Avoid os.system:

  # ❌ Platform-dependent and insecure
  os.system("cp source.txt destination.txt")

Use shutil.copy() for most use cases and shutil.copy2() to preserve metadata. Always handle exceptions for robustness!