Your first ephemeral run

This tutorial walks through running a tool with conda-exec for the first time.

Prerequisites

• conda 25.1 or later

• conda-rattler-solver installed

• conda-exec installed (conda install conda-exec)

Step 1: Run a tool

Run ruff, a fast Python linter:

conda exec

conda exec ruff check .

ce (standalone)

ce ruff check .

On the first run, you will see a progress message while the environment is created:

Creating environment for ruff... done (3.2s)

conda-exec:

1. Solves the environment (finding ruff and its dependencies)

2. Downloads and installs packages into a cache directory

3. Finds the ruff binary in the cached environment

4. Runs ruff check . and forwards the output

Step 2: Run it again

conda exec ruff check .

This time it starts instantly with no progress message because the cached environment already exists.

Step 3: Try the standalone alias

ce ruff check .

ce is a standalone command that works the same as conda exec.

Tip

Run conda exec --list to see all cached environments and their sizes.

What happened?

conda-exec created a cached environment at ~/.conda/exec/envs/ruff--<hash>/. This environment is isolated and disposable. It is not on your PATH and does not affect your other conda environments.

Next steps

conda-exec can also run Python scripts with inline dependency metadata. See the Run a script tutorial to learn how.