Pin package versions

conda-exec accepts version constraints as part of the tool argument, using conda’s match spec syntax.

Bare package name

With no constraint, the solver picks the latest version available:

conda exec ruff check .

Single version constraint

Note

Always quote match specs that contain version operators (>, <, =, !). Without quotes, the shell may interpret these characters as redirections or other special syntax.

Quote the tool argument when it contains a version specifier:

conda exec "ruff>=0.4" check .

The binary name (ruff) is extracted from the match spec automatically.

Multiple constraints

Combine constraints with commas for a version range:

conda exec "ruff>=0.4,<0.5" check .

Exact version

Pin to an exact version:

conda exec "ruff==0.4.3" check .

Add extra packages with –with

Use --with to install additional packages alongside the tool. Each --with value is a full match spec:

conda exec --with "python=3.12" jupyter lab
conda exec --with pytest --with hypothesis ruff check .

How specs affect caching

Each unique combination of specs and channels produces a different cache key. These three invocations create three separate cached environments:

conda exec ruff check .                    # ruff--<hash1>
conda exec "ruff>=0.4" check .             # ruff--<hash2>
conda exec --with pytest ruff check .      # ruff--<hash3>

This means you can have multiple versions of the same tool cached simultaneously without conflicts.

Force re-creation

If a cached environment is outdated or you want to pick up a newly released version, use --refresh to discard the existing cache and solve again:

conda exec --refresh ruff check .

This removes the cached environment for that specific spec/channel combination and creates a fresh one.