uv

init

# Create project in a new dir
cd ~ # parent folder
uv init demo

# Create project in the current dir
mkdir demo
cd demo
uv init

sync

• What is does?
• Read your pyproject.toml
• Create a .venv/ (if not there yet)
• Install all dependencies
• Create/update the uv.lock file
• It's similar to npm i

uv sync
uv sync --extra dev # also install "project.optional-dependencies.dev"

run

# Run the entrypoint of the project
uv run python main.py
uv run python main.py --arg1 value1

# Run python code
uv run python - <<'EOF'
  import sys
  sys.exit(1)
EOF

# Run python code interactively (and specify the version)
uv run --python [email protected] -- python
uv run --python 3.12.0 -- python

# Run an arbitrary command of a dependency
uv run ruff check

# Run a custom script
uv run start

# Run test deps
uv run pytest tests/

add

• Adds a dependency into pyproject.toml and installs it in the virtual environment .venv/

uv add "langchain"

# Add a dependency for a single file
# Dependency are added as comments to the file
echo 'import requests; print(requests.get("http://example.com"))' > demo.py
uv add requests --script demo.py

# Run it
uv run demo.py

uv lock

uv lock

uv python

• Install a python version for the current project

uv python install 3.10 3.11 3.12

uv python pin 3.11 # pin a version for the cwd

uv tool (uvx)

• Run tools in an ephemeral environment (similar to pipx, npx, etc)

# run
uvx pycowsay 'hello world!'
uv tool run pycowsay 'hello world!' # same

# install
uv tool install ruff # just install without running