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Using the IGWN Conda Distribution

This page describes how to use the the IGWN Conda Distribution, either via CVMFS, or with a local conda installation.

Supported platforms

The IGWN Conda Distribution is fully supported on Linux x86_64 only.

Best-effort support is provided for the following platforms

  • macOS x86_64
  • Windows x86_64

Using pre-built environments with CVMFS

The IGWN Conda Distribution is automatically built for Linux x86_64 and distributed with CVMFS as part of the IGWN Software Repository.

On systems where the CVMFS repository is available the IGWN Conda Distribution is available under


To use the IGWN Conda Distribution in CVMFS, following these steps:

1. Configure conda

On all IGWN shared computing centres, conda should be pre-built and pre-configured without any manual steps required from the user.

On other systems, conda can be configured with the following shell command

source /cvmfs/

Users of Mamba may also wish to source the script to fully configure that tool:

source /cvmfs/
source /cvmfs/

2. Activate a pre-built environment

The IGWN Conda Distribution in CVMFS provides a number of pre-built environments for Linux users, see Environments for full details of what environments are available, or run

conda env list

for a complete list. Once you have chosen, simply run

conda activate <env>

to activate the relevant environment.

Example: activating the igwn environment

conda activate igwn

Local usage

This section is designed for users of conda on a local machine, i.e. a laptop or desktop workstation. Users of the IGWN shared computing centres should refer to the CVMFS section above.

This guide presents a tiny subset of the conda capabilities, for more information see the links at the bottom of the page.

1. Install conda

The first thing to do is to install conda itself. We recommend installing conda from Mambaforge:

  1. Download the installer on the command line:

    curl -L -O$(uname)-$(uname -m).sh
  2. Install it:

    bash Mambaforge-$(uname)-$(uname -m).sh

    Note: the installer script will present a few questions to answer.

  1. Click here to download the installer (direct download link, parent page here).

  2. Double-click the installer file in your file browser.

2. Check the conda configuration

When installed correctly, you should be able to open a new terminal window and verify that conda works correctly:

conda info

This should produce output that looks something like this:

> conda info

     active environment : None
       user config file : C:\Users\mariecurie\.condarc
 populated config files : C:\Users\mariecurie\.condarc
          conda version : 4.10.3
    conda-build version : 3.21.4
         python version :
       virtual packages : __win=0=0
       base environment : C:\Users\mariecurie\Miniconda3  (writable)
      conda av data dir : C:\Users\mariecurie\Miniconda3\etc\conda
  conda av metadata url : None
           channel URLs :
          package cache : C:\Users\mariecurie\Miniconda3\pkgs
       envs directories : C:\Users\mariecurie\Miniconda3\envs
               platform : win-64
             user-agent : conda/4.10.3 requests/2.26.0 CPython/3.7.6 Windows/10 Windows/10.0.19041
          administrator : False
             netrc file : None
           offline mode : False

The output here will depend upon your choice of install location, and the operating system you are running.

Ensure that the conda-forge channel is configured

IGWN software is uploaded to the conda-forge package channel only. If you don't see references to conda-forge in the output of conda info above, you will have to manually configure the conda-forge channel as follows:

conda config --add channels conda-forge
conda config --set channel_priority strict

3. Create a new environment

Each installation of conda comes with a default environment named base; this is the environment that contains conda itself. It is highly recommended to not install scientific software into the base environment, instead you should create a new environment. This will help make sure that your conda installer doesn't become inoperable, and can be upgraded independently of the scientific software stack you are using.

To create a new environment called igwn, run the following in a terminal window:

conda create --name igwn

4. Activate the new environment

To use the environment, it must be 'activated', type the following:

conda activate igwn

You should then find that any scripts installed into the new environment are available for use, at the moment we don't have anything.

If you wish, when you finish working in an environment, you can deactivate it via

conda deactivate igwn

This should return your shell session back to the same state it was in before you activated the environment.

5. Install some packages

To install packages into the activate environment, just run conda install and pass it the names of all of the packages you want. For example, to install Python 3.9 and GWpy:

conda install "python=3.9" gwpy

Conda will then work out what exact versions of Python, GWpy and any other packages (dependencies) to install, and might ask you to proceed:

Proceed ([y]/n)?

Type y and press Enter to proceed.

You should immediately be able to start using the new software you have installed.

To install software into a different environment that isn't the active one, you can pass --name <env> to the conda install command:

conda install --name igwn gwpy

Quote package names when specifying versions

To minimise the chance of your shell getting confused, it's a good idea to put quotation marks around package names when calling conda install or similar commands. This is especially important when adding version specifiers to the package name, e.g. conda install gwpy>=2.1.0 will probably do something you don't want it to, but conda install "gwpy>=2.1.0" will do what it's supposed to.

Use conda list to list packages in an environment

The conda list command can be used to print the list of packages in an environment.

6. Updating packages

Updating specific packages

To update packages in an environment, simply run the following in a terminal window:

conda update <package> <package>


conda update gwpy

Conda will then work out what to do to update the requested packages and any upstream packages that need to be updated at the same time.

Conda might not update absolutely everything

In order to solve the environment to update most packages, conda may end up not updating some packages to the absolutely latest version. This will happen if the latest version of PackageA conflicts with the latest version of PackageB.

If you absolutely require that PackageA is updated, you should manually update that one using conda update packagea.

Updating all packages

To update all packages in an environment, run

conda update --all

For more information on conda and its usage, please refer to one of the following sources:

For more advanced usage tips related to use of conda for IGWN research, please refer to Advanced usage.