State of Conda, Oct. 2014

I have been using Conda (via Miniconda) for managing my Python development environments and packages for close to a year now, so I thought I’d write up my thoughts so far for others.

Conda is both an environment manager (an alternative to virtualenv) and an installation tool (an alternative to pip). You can also use Conda to build your packages and distribute them via Binstar.

So, what does Conda do well and what needs improvement? Continue reading “State of Conda, Oct. 2014”

State of Conda, Oct. 2014

Using Conda Environments and the Fish Shell

I recently started over with a fresh development environment and decided to try something new: I’m using Python 3 via miniconda. The first real hiccup I’ve run into is that conda’s environment activation/deactivation scheme only works in bash or zsh. I use fish. There is an open PR to get fish support for conda but in the meantime I hacked something together to help me out.

"Activating" a conda environment does a couple of things:

  • Puts the environment’s "bin" directory at the front of the PATH environment variable.
  • Sets a CONDA_DEFAULT_ENV environment variable that tells conda in which environment to do things when none is specified.
  • Adds the environment name to the prompt ala virtualenv.

Deactivating the environment resets everything to its pre-activation state. The fish functions I put together work like this:

~ > type python
python is /Users/---/miniconda3/bin/python
~ > condactivate env-name
(env-name) ~ > type python
python is /Users/---/miniconda3/envs/env-name/bin/python
(env-name) ~ > deactivate
~ > type python
python is /Users/---/miniconda3/bin/python

Here’s the text of the functions:

function condalist -d 'List conda environments.'
for dir in (ls $HOME/miniconda3/envs)
echo $dir
function condactivate -d 'Activate a conda environment' -a cenv
if test -z $cenv
echo 'Usage: condactivate <env name>'
return 1
# condabin will be the path to the bin directory
# in the specified conda environment
set condabin $HOME/miniconda3/envs/$cenv/bin
# check whether the condabin directory actually exists and
# exit the function with an error status if it does not
if not test -d $condabin
echo 'Environment not found.'
return 1
# deactivate an existing conda environment if there is one
if set -q __CONDA_ENV_ACTIVE
# save the current path
# put the condabin directory at the front of the PATH
set -xg PATH $condabin $PATH
# this is an undocumented environmental variable that influences
# how conda behaves when you don't specify an environment for it.
set -xg CONDA_DEFAULT_ENV $cenv
# set up the prompt so it has the env name in it
functions -e __original_fish_prompt
functions -c fish_prompt __original_fish_prompt
function fish_prompt
set_color blue
echo -n '('$CONDA_DEFAULT_ENV') '
set_color normal
# flag for whether a conda environment has been set
set -xg __CONDA_ENV_ACTIVE 'true'
function deactivate -d 'Deactivate a conda environment'
if set -q __CONDA_ENV_ACTIVE
# set PATH back to its default before activating the conda env
# unset this so that conda behaves according to its default behavior
# reset to the original prompt
functions -e fish_prompt
functions -c __original_fish_prompt fish_prompt
functions -e __original_fish_prompt
# aliases so condactivate and deactivate can have shorter names
function ca -d 'Activate a conda environment'
condactivate $argv
function cda -d 'Deactivate a conda environment'
deactivate $argv
# complete conda environment names when activating
complete -c condactivate -xA -a "(condalist)"
complete -c ca -xA -a "(condalist)"
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Or you can download it from

To use these, add them to the ~/.config/fish/ directory and source them from the end of the ~/.config/fish/ file:

source $HOME/.config/fish/
Using Conda Environments and the Fish Shell