> "uv add"
One life-changing thing I've been using `uv` for:
System python version is 3.12:
$ python3 --version
Python 3.12.3
A script that requires a library we don't have, and won't work on our local python: $ cat test.py
#!/usr/bin/env python3
import sys
from rich import print
if sys.version_info < (3, 13):
print("This script will not work on Python 3.12")
else:
print(f"Hello world, this is python {sys.version}")
It fails: $ python3 test.py
Traceback (most recent call last):
File "/tmp/tmp/test.py", line 10, in <module>
from rich import print
ModuleNotFoundError: No module named 'rich'
Tell `uv` what our requirements are $ uv add --script=test.py --python '3.13' rich
Updated `test.py`
`uv` updates the script: $ cat test.py
#!/usr/bin/env python3
# /// script
# requires-python = ">=3.13"
# dependencies = [
# "rich",
# ]
# ///
import sys
from rich import print
if sys.version_info < (3, 13):
print("This script will not work on Python 3.12")
else:
print(f"Hello world, this is python {sys.version}")
`uv` runs the script, after installing packages and fetching Python 3.13 $ uv run test.py
Downloading cpython-3.13.5-linux-x86_64-gnu (download) (33.8MiB)
Downloading cpython-3.13.5-linux-x86_64-gnu (download)
Installed 4 packages in 7ms
Hello world, this is python 3.13.5 (main, Jun 12 2025, 12:40:22) [Clang 20.1.4 ]
And if we run it with Python 3.12, we can see that errors: $ uv run --python 3.12 test.py
warning: The requested interpreter resolved to Python 3.12.3, which is incompatible with the script's Python requirement: `>=3.13`
Installed 4 packages in 7ms
This script will not work on Python 3.12
Works for any Python you're likely to want: $ uv python list
cpython-3.14.0b2-linux-x86_64-gnu <download available>
cpython-3.14.0b2+freethreaded-linux-x86_64-gnu <download available>
cpython-3.13.5-linux-x86_64-gnu /home/dan/.local/share/uv/python/cpython-3.13.5-linux-x86_64-gnu/bin/python3.13
cpython-3.13.5+freethreaded-linux-x86_64-gnu <download available>
cpython-3.12.11-linux-x86_64-gnu <download available>
cpython-3.12.3-linux-x86_64-gnu /usr/bin/python3.12
cpython-3.12.3-linux-x86_64-gnu /usr/bin/python3 -> python3.12
cpython-3.11.13-linux-x86_64-gnu /home/dan/.local/share/uv/python/cpython-3.11.13-linux-x86_64-gnu/bin/python3.11
cpython-3.10.18-linux-x86_64-gnu /home/dan/.local/share/uv/python/cpython-3.10.18-linux-x86_64-gnu/bin/python3.10
cpython-3.9.23-linux-x86_64-gnu <download available>
cpython-3.8.20-linux-x86_64-gnu <download available>
pypy-3.11.11-linux-x86_64-gnu <download available>
pypy-3.10.16-linux-x86_64-gnu <download available>
pypy-3.9.19-linux-x86_64-gnu <download available>
pypy-3.8.16-linux-x86_64-gnu <download available>
graalpy-3.11.0-linux-x86_64-gnu <download available>
graalpy-3.10.0-linux-x86_64-gnu <download available>
graalpy-3.8.5-linux-x86_64-gnu <download available>
