Quickstart#

Installation#

conda install -c conda-forge conda-exec

Install conda-pypi as well if you want scripts with top-level PEP 723 dependencies from PyPI, and conda-lockfiles if you want script lock support.

Basic usage#

Run a command from a conda package without installing it into your current environment:

conda exec

conda exec ruff check .

ce (standalone)

ce ruff check .

The first invocation creates a cached environment. Later runs reuse that environment and skip the solve/download step.

conda-exec quickstart demo showing a first tool run, cache reuse, the ce alias, and cache listing

For more command-line patterns, see Run command-line tools.

Version constraints#

Pin a specific version using a match spec as the tool argument:

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

The binary name is extracted from the match spec automatically.

Extra packages#

Add additional packages to the ephemeral environment:

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

Custom channels#

Use packages from other channels:

conda exec -c bioconda samtools view file.bam

Run scripts#

Run a Python script that declares its dependencies inline using PEP 723 metadata:

# /// script
# requires-python = ">=3.12"
# dependencies = ["requests", "rich"]
#
# [tool.conda]
# channels = ["conda-forge", "bioconda"]
# dependencies = ["samtools>=1.19"]
# ///

import requests
from rich import print
print("Hello from conda exec!")

conda exec script.py

conda-exec parses the inline metadata, creates a cached environment with all declared dependencies (both conda and PyPI), and runs the script.

Note

Scripts with PyPI dependencies require conda-pypi to be installed. Conda-only scripts (using only [tool.conda] dependencies) work without it.

Scripts without metadata run directly with the current Python.

Lock script environments#

Generate lock data when a script should be repeatable across machines or after cache cleanup:

conda exec --lock script.py

This writes sidecar lock data next to the script. Future normal runs use the lock data when it matches the script’s dependency metadata.

For the step-by-step workflow, see Share a locked script.