Python venv module cannot add virtual environment name to PS1, when using PROMPT_COMMAND?

Question

I use the official Git Bash prompt support for displaying the current branch as part of the prompt.

My problem is that activating a Python virtual environment ( python -m venv <dir> ) using source bin/activate doesn't display the virtual environment name - (atlassian-watchdog) - as part of the Bash prompt:

nlykkei:~/projects/atlassian-watchdog (master *)$

I've a strong feeling that it's failing, because I use PROMPT_COMMAND in ~/.bashrc instead of PS1 , but GIT_PS1_SHOWCOLORHINTS works only with PROMPT_COMMAND .

Is there any way to use PROMPT_COMMAND with Python virtual environments, so that the environment name gets added to the prompt, when it's active?

~/.git-prompt.sh :

# If you would like a colored hint about the current dirty state, set
# GIT_PS1_SHOWCOLORHINTS to a nonempty value. The colors are based on
# the colored output of "git status -sb" and are available only when
# using __git_ps1 for PROMPT_COMMAND or precmd.

bin/activate :

if [ -z "${VIRTUAL_ENV_DISABLE_PROMPT:-}" ] ; then
    _OLD_VIRTUAL_PS1="${PS1:-}"
    if [ "x(atlassian-watchdog) " != x ] ; then
       PS1="(atlassian-watchdog) ${PS1:-}"
    else
    if [ "`basename \"$VIRTUAL_ENV\"`" = "__" ] ; then
        # special case for Aspen magic directories
        # see http://www.zetadev.com/software/aspen/
        PS1="[`basename \`dirname \"$VIRTUAL_ENV\"\``] $PS1"
    else
        PS1="(`basename \"$VIRTUAL_ENV\"`)$PS1"
    fi
    fi
    export PS1
fi

~/.bashrc :

# git prompt
source ~/.git-prompt.sh
GIT_PS1_SHOWCOLORHINTS=1
PROMPT_COMMAND='__git_ps1 "\u:\w" "\\\$ "'

Answer 1

I just bumped into the same thing. Until git and venv work well together natively, consider including the part from env/bin/activate that sets the prompt in the PROMPT_COMMAND as a new function. Here's one way of doing that. See the comments for more info.

~/.bashrc :

# [...]

# Source in the original git-prompt.sh as necessary.
. ~/.git-prompt.sh

# Source a new function to be used as the prompt command (see below).
. ~/.git_ps1_venv

# Set whatever features you want.
GIT_PS1_SHOWCOLORHINTS=1

# I choose to have my original PS1 in a separate variable to keep the
# PROMPT_COMMAND line readable, and to be able to query it if needed.
ORIG_PS1='\u:\w'

# Call the new function (see below).
PROMPT_COMMAND='__git_ps1_venv "'"${ORIG_PS1}"'" "\\\$ "'

# [...]

~/.git_ps1_venv :

#!/usr/bin/env bash

__git_ps1_venv() {
  # Some local storage to not clutter the environment
  local pre=$1
  local post=$2

  # Let's only check for a virtual environment if the VIRTUAL_ENV variable is
  # set. This should eek out a little more performance when we're not in one
  # since we won't need to call basename.
  if [ -n "${VIRTUAL_ENV}" ] && [ -z "${VIRTUAL_ENV_DISABLE_PROMPT:-}" ]; then

    # There's no need to set _OLD_VIRTUAL_PS1 since it's used to replace PS1 on
    # a deactivate call. And since we're using PROMPT_COMMAND, PS1 isn't used.
    #
    #_OLD_VIRTUAL_PS1="${pre:-}"

    # The python venv module hard-codes the name of the virtual environment into
    # the activate script for my configuration, so we need to pull it out of
    # VIRTUAL_ENV to have an appropriate prefix. If we're doing that, might has
    # well comment out the hard-coded part and rely on the else in the
    # if-statement that follows it.
    #
    #if [ "x(env) " != x ] ; then
    #  PS1="(env) ${PS1:-}"
    #else

    # This is the else of the if-statement with PS1 replaced with pre.
    # Otherwise, no changes.
    if [ "`basename \"${VIRTUAL_ENV}\"`" = "__" ] ; then
      # special case for Aspen magic directories
      # see http://www.zetadev.com/software/aspen/
      pre="[`basename \`dirname \"${VIRTUAL_ENV}\"\``] ${pre}"
    else
      pre="(`basename \"${VIRTUAL_ENV}\"`) ${pre}"
    fi
  fi

  # Call the actual __git_ps1 function with the modified arguments
  __git_ps1 "${pre}" "${post}"
}