Quick & dirty script to migrate pyenvs from one python version to a new one (e.g. 3.11.1 to 3.12.2). Old virtualenvs are first deleted in the process!

upgrade_pyenvs.zsh

old=$1
new=$2

if [[ -z "$old" || -z "$new" ]]; then
  echo "usage upgrade_pyenvs.zsh <old_version> <new_version>"
  exit 1
fi

for myenv in $(pyenv versions --bare | rg $old/envs); do
  myenv=${myenv##$old/envs/}
  echo "Upgrading $myenv"
  pyenv shell $myenv
  python -m pip freeze > requirements_$old_${myenv}.txt
  python -m pip freeze | cut -d"=" -f1 > requirements_${myenv}_names.txt
  
  ### !!!! this will first delete the "old" virtualenv, since renaming is not possible!
  pyenv virtualenv-delete $myenv
  if [[ $? -ne 0 ]]; then
    echo "Failed to delete or chose not to delete $myenv"
    continue
  fi
  pyenv virtualenv $new $myenv
  pyenv shell $myenv
  
  # this might throw errors that you will have to fix afterwards
  python -m pip install -r requirements_${myenv}_names.txt
done