TITLE: Python conda virtual environment in bash prompt
DATE: 2019-02-28
AUTHOR: John L. Godlee
====================================================================
I was forced to use the python package manager conda for some work,
as it proved to be the easiest way to install a certain python
module. A nice thing about conda is the ability to set up multiple
virtual environments which can each use different versions of
python modules. You can set a conda virtual environment with:
conda create -n envname
There are also lots of other options to set such as the python
version (python=3.6).
Then the environment is activated with:
source activate envname
By default, conda puts the name of the virtual environment
(envname) at the start of the PS1 bash prompt. For those of us with
customised bash prompts, this can look really ugly. For instance,
my prompt normally looks like this:
It would be nice to put the environment name somewhere else in the
prompt, which is what I set out to do. So the first things to do is
to stop conda putting the env name at the start of the prompt. Edit
~/.condarc to include:
changeps1: false
Then in ~/.bash_profile (or ~/.bashrc if on Linux), add the
following function above the PS1= lines:
get_conda_env ()
{
if [ ! -z "$CONDA_DEFAULT_ENV" ]; then
printf -- "%s" "($CONDA_DEFAULT_ENV)"
else
printf -- "%s" ""
fi
}
Then in the PS1= lines it's simple to just call the variable
created by get_conda_env():
PS1='$(check_conda_env)'
y bash prompt definition currently looks like this:
PS1='┏' # Elbow
PS1+='[\T]' # Time
PS1+=' ' # Space
PS1+='\u@\h' # User@hostname
PS1+=' ' # Space
PS1+='\[\e[31m\]\w\[\e[m\]' # current dir
PS1+=' ' # Space
PS1+='\[\e[96m\]$(__git_ps1 "[%s]")\[\e[m\]' # git branch
PS1+=' ' # Space
PS1+='\[\e[34m\]$(get_conda_env)\[\e[m\]' # conda env
PS1+=' ' # Space
PS1+='\n' # New line
PS1+='┗' # Elbow
PS1+='$' # $
PS1+=' ' # Space
