4 snippets across 3 stacks - Docker, Bash & Linux, Python
Also written as copy files
COPY [--chown=<user>:<group>] <src>... <dest>COPY package.json package-lock.json ./
COPY --chown=appuser:appuser . /app/Note COPY only handles local files from the build context. Copy dependency manifests (package.json, requirements.txt) before the rest of the source code so that dependency-install layers are cached when only your application code changes.
docker cp <container>:<path> <host_path>
docker cp <host_path> <container>:<path>docker cp web-api:/app/logs/error.log ./error.log
docker cp ./hotfix.js web-api:/app/hotfix.jsNote Works on both running and stopped containers. Useful for extracting crash logs or injecting a config file for debugging. Changes via cp do not persist across container recreation - use volumes for anything permanent.
cp [options] source destinationcp config.yml config.yml.bak
cp -r templates/ /opt/app/templates/
cp -i report.csv ~/Desktop/Note -r is required for directories (recursive copy). -i prompts before overwriting. Without -i, cp silently overwrites the destination. Use -a to preserve permissions, timestamps, and symlinks.
with open(path, 'rb') as f:
data = f.read()# Copy a binary file
with open("image.png", "rb") as src:
data = src.read()
with open("copy.png", "wb") as dst:
dst.write(data)
print(f"Copied {len(data)} bytes")Note Use 'rb' / 'wb' modes for binary files (images, archives, etc.). Never open binary files in text mode; it corrupts the data on some platforms.