My super sweet Python run-module-in-a-venv script

venvexec.sh

#! /bin/bash -eu
shopt -s failglob

force=
while getopts "f" flag
do
  case $flag in
  f) force=y ;;
  esac
done
shift $((OPTIND - 1))

module_path=$1

log() {
  echo "$@" >&2
}

die() {
  log "$@"
  exit 1
}

[[ -e $module_path ]] || die "module does not exist: ${module_path}"
[[ -d $module_path ]] || die "module is not a directory: ${module_path}"
[[ -f $module_path/__main__.py ]] || die "module does not have a top-level script: ${module_path}"

venv_path=${module_path}_venv

cmp_optional() {
  [[ ! -e $1 && ! -e $2 ]] && return 0
  [[ -e $1 && -e $2 ]] || return 1
  cmp --silent $1 $2
}

if [[ -e $venv_path ]]
then
  if [[ -n "$force" ]]
  then
    log "discarding venv - force requested"
    rm -r $venv_path
  fi
  if ! cmp_optional $module_path/requirements.txt $venv_path/requirements.txt
  then
    log "discarding venv - requirements have changed"
    rm -r $venv_path
  fi
fi

if [[ ! -e $venv_path ]]
then
  log "creating venv at ${venv_path}"

  python3 -m venv $venv_path

  if [[ -f $module_path/requirements.txt ]]
  then
    cp $module_path/requirements.txt $venv_path/
    $venv_path/bin/pip install -r $venv_path/requirements.txt
  fi

  ln -s $(readlink -f $module_path) $venv_path/lib/*/site-packages/
fi

exec $venv_path/bin/python -m $(basename $module_path)