Environment Variables

Configure conda using environment variables for temporary or system-wide settings

Overview

Conda can be configured using environment variables prefixed with CONDA_. These variables provide a way to:

• Temporarily override configuration for a single command
• Set system-wide defaults without modifying .condarc files
• Configure conda in containerized or CI/CD environments
• Pass configuration to conda programmatically

Environment variables have higher precedence than .condarc files but lower precedence than command-line arguments.

Core Environment Variables

These environment variables are automatically set by conda and used to track the current environment state:

CONDA_PREFIX · string

Absolute path to the currently active conda environment. This is the primary way to detect if a conda environment is active.

Example: /home/user/miniconda3/envs/myenv

CONDA_DEFAULT_ENV · string

Name of the currently active environment. For named environments, this is the environment name. For environments created with a path, this is the full path.

Example: myenv or /path/to/env

CONDA_SHLVL · integer

Shell level - indicates how many conda environments are currently stacked (activated on top of each other). Starts at 0 when no environment is active, increments with each activation.

Example: 1 (one environment active), 2 (stacked environments)

CONDA_PROMPT_MODIFIER · string

The string that is prepended to your shell prompt when an environment is active.

Example: (myenv)

CONDA_EXE · string

Full path to the conda executable being used.

Example: /home/user/miniconda3/bin/conda

CONDA_PYTHON_EXE · string

Path to the Python interpreter in the base conda environment.

Example: /home/user/miniconda3/bin/python

_CONDA_ROOT · string

Path to the root conda installation directory (base environment).

Example: /home/user/miniconda3

Configuration Environment Variables

Any configuration parameter in .condarc can be set via environment variables using the format CONDA_<PARAMETER_NAME> (uppercase, with underscores).

Common Configuration Variables

CONDA_CHANNELS · string

Comma-separated list of channels to use. Overrides the channels setting in .condarc.

export CONDA_CHANNELS="conda-forge,defaults"

CONDA_CHANNEL_PRIORITY · string

Set channel priority to strict, flexible, or disabled.

export CONDA_CHANNEL_PRIORITY="strict"

CONDA_ENVS_DIRS · string

Path separator-delimited list of directories to search for environments.

# Linux/macOS
export CONDA_ENVS_DIRS="/opt/envs:$HOME/envs"

# Windows
set CONDA_ENVS_DIRS=C:\envs;%USERPROFILE%\envs

CONDA_PKGS_DIRS · string

Path separator-delimited list of package cache directories.

export CONDA_PKGS_DIRS="/scratch/pkgs:$HOME/.conda/pkgs"

CONDA_SOLVER · string

Specify which solver to use: libmamba or classic.

export CONDA_SOLVER="libmamba"

CONDA_SUBDIR · string

Override the platform/architecture subdirectory (e.g., linux-64, osx-arm64, win-64).

export CONDA_SUBDIR="linux-64"

Network Configuration

CONDA_SSL_VERIFY · string

Control SSL certificate verification. Set to true, false, or a path to a CA bundle.

export CONDA_SSL_VERIFY="false"  # Disable (not recommended)
export CONDA_SSL_VERIFY="/path/to/cacert.pem"  # Use custom CA

HTTP_PROXY · string

HTTP proxy server URL.

export HTTP_PROXY="http://proxy.company.com:8080"

HTTPS_PROXY · string

HTTPS proxy server URL.

export HTTPS_PROXY="https://proxy.company.com:8080"

Behavior Modifiers

CONDA_ALWAYS_YES · string

Automatically answer yes to all prompts. Set to true or false.

export CONDA_ALWAYS_YES="true"

CONDA_QUIET · string

Suppress progress bars and non-essential output.

export CONDA_QUIET="true"

CONDA_VERBOSITY · integer

Control output verbosity. Higher numbers mean more verbose output (0-4).

export CONDA_VERBOSITY="2"

CONDA_JSON · string

Output results in JSON format.

export CONDA_JSON="true"

Developer Variables

CONDA_DEV · string

Enable development mode for running conda from source.

export CONDA_DEV="1"

CONDA_NO_PLUGINS · string

Disable all conda plugins except built-in ones.

export CONDA_NO_PLUGINS="true"

CONDA_NO_LOCK · string

Disable file locking (useful in some network file systems, but dangerous).

export CONDA_NO_LOCK="1"

How to Set Environment Variables

Temporary (Current Session Only)

Linux/macOS:

export CONDA_CHANNELS="conda-forge,defaults"
conda install numpy

Windows (CMD):

set CONDA_CHANNELS=conda-forge,defaults
conda install numpy

Windows (PowerShell):

$env:CONDA_CHANNELS="conda-forge,defaults"
conda install numpy

Permanent (All Sessions)

Linux/macOS (bash): Add to ~/.bashrc or ~/.bash_profile:

export CONDA_CHANNELS="conda-forge,defaults"
export CONDA_SOLVER="libmamba"

Linux/macOS (zsh): Add to ~/.zshrc:

export CONDA_CHANNELS="conda-forge,defaults"
export CONDA_SOLVER="libmamba"

Windows:

1. Open System Properties → Advanced → Environment Variables
2. Add new User or System variables with CONDA_ prefix

For a Single Command

Linux/macOS:

CONDA_CHANNELS="conda-forge" conda install numpy

Windows (CMD):

set CONDA_CHANNELS=conda-forge && conda install numpy

Common Use Cases

CI/CD Pipeline

Configure conda for automated builds:

export CONDA_ALWAYS_YES="true"
export CONDA_QUIET="true"
export CONDA_SOLVER="libmamba"
export CONDA_CHANNELS="conda-forge,defaults"

conda create -n build-env python=3.11
conda activate build-env
conda install numpy pandas

Corporate Proxy Environment

Configure network access through corporate proxy:

export HTTP_PROXY="http://user:[e-mail]:8080"
export HTTPS_PROXY="http://user:[e-mail]:8080"
export CONDA_SSL_VERIFY="/etc/ssl/certs/ca-bundle.crt"

conda install matplotlib

Cross-Platform Package Creation

Build packages for different platforms:

# Build for Linux on macOS
CONDA_SUBDIR="linux-64" conda create -n linux-env python=3.11

# Build for ARM on x86
CONDA_SUBDIR="osx-arm64" conda create -n arm-env python=3.11

Testing Different Solvers

Quickly test both solvers:

# Try with classic solver
CONDA_SOLVER="classic" conda install scipy

# Try with libmamba solver
CONDA_SOLVER="libmamba" conda install scipy

Priority and Overrides

Configuration sources are merged in this order (highest to lowest priority):

1. Command-line flags (e.g., --channel conda-forge)
2. Environment variables (e.g., CONDA_CHANNELS)
3. Environment .condarc ($CONDA_PREFIX/.condarc)
4. User .condarc (~/.condarc)
5. System .condarc ($CONDA_ROOT/.condarc)

To mark a variable as final and prevent it from being overridden by lower priority sources, append !important:

export CONDA_CHANNELS="conda-forge!important"

Environment Variable String Delimiters

For list parameters, conda uses specific delimiters:

• Most lists: Comma (,)
• Path lists (envs_dirs, pkgs_dirs): OS path separator (: on Unix, ; on Windows)
• Pinned/disallowed packages: Ampersand (&)

Examples:

# Comma-separated
export CONDA_CHANNELS="conda-forge,bioconda,defaults"

# Path separator
export CONDA_ENVS_DIRS="/opt/envs:/home/user/envs"  # Unix
set CONDA_ENVS_DIRS=C:\envs;D:\envs  # Windows

# Ampersand-separated
export CONDA_PINNED_PACKAGES="python=3.11&numpy>=1.20"

Checking Environment Variables

View all conda-related environment variables:

# Linux/macOS
env | grep CONDA

# Windows (CMD)
set | findstr CONDA

# Windows (PowerShell)
Get-ChildItem Env: | Where-Object {$_.Name -like "*CONDA*"}

View how conda interprets all configuration:

conda config --show
conda config --show-sources

See Also

• .condarc Configuration - File-based configuration
• Settings Reference - Complete list of all settings
• conda activate - Environment activation details