Crude script to activate a Python virtual environment in Git Bash. Probably works w/ MSYS2, not sure on Cygwin -> needs usecases.

activate

# Usage like activating venv on Linux: source /path/to/env/Scripts/activate
# Use 'deactivate_venv' on CL or pass argument '--deactivate' on the source command to deactivate env.

deactivate_venv() {
  if [[ -z ${_OLD_VIRTUAL_PATH} ]]; then
    printf "No virtual environment found!\n"
  else
    export PATH=$_OLD_VIRTUAL_PATH
    export PS1=$_OLD_VIRTUAL_PS1
    unset _OLD_VIRTUAL_PATH
    unset _OLD_VIRTUAL_PS1
    unset VIRTUAL_ENV
    
    printf "Python virtual environment deactivated!\n"
  fi
}

activate_venv() {
  __VIRTUAL_BIN__=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
  VIRTUAL_ENV=$(sed -n '2p' "${__VIRTUAL_BIN__}/activate.bat")
  
  export $(echo "$VIRTUAL_ENV" | sed -e 's/set //' -e 's/\"//g')
  export _OLD_VIRTUAL_PATH=$PATH
  export PATH=$__VIRTUAL_BIN__:$PATH
  export _OLD_VIRTUAL_PS1=$PS1
  export PS1='\[\033]0;$TITLEPREFIX:${PWD//[^[:ascii:]]/?}\007\]\n\[\033[32m\]\u@\h \[\033[35m\]$MSYSTEM \[\033[33m\]\w\[\033[36m\]`__git_ps1`\[\033[0m\]\n(`basename $VIRTUAL_ENV`) \$ '
  
  
  printf "Python virtual environment activated in %s\n" "$VIRTUAL_ENV"
}

main() {
  if [[ $1 == "--deactivate" ]]; then
    deactivate_venv
  else
    deactivate_venv
    activate_venv
 fi
}

main "$@"

# V20160813: append venv dir to PS1
# V20160312: strange line number thingie...
# V20160308: added deactivation method
# V20160307: It's-a-Bash! WINDOWS ONLY!