A totally untested script for upgrading a virtualenv

rebuild-virtualenv

#!/bin/bash

set -eu

if [[ -z "${1-}" ]]; then
  echo "USAGE: $0 VIRTUAL_ENV_DIR"
  exit 1
fi

venv="$1"
. "$venv/bin/activate"

cleanup() {
  [ -e "${tmp_reqs-}" ] && rm "${tmp_reqs}"
  [ ! -e "$venv" ] && mv "$venv.old" "$venv"
}

trap cleanup EXIT

tmp_reqs="$(mktemp /tmp/requirements.txt.XXXXX)"

pip freeze > "$tmp_reqs"
deactivate
mv "$venv" "$venv.old"
virtualenv "$venv"
. "$venv/bin/activate"
pip install -r "$tmp_reqs"

echo "Done."
echo "Remove the old virtualenv once you've confirmed that the new one works:"
echo "    $venv.old"