post_install() {
  post_upgrade
}

post_upgrade() {
  echo '>>> Setting up shared system-wide drush configuration'
  echo '    by symlinking ~/.drush to /etc/drush for all users.'
  for user in $(cut --fields=1,6 --delimiter=: /etc/passwd | grep :/home); do
    user=($(echo $user | tr ':' ' '))
    path="${user[1]}/.drush"
    user="${user[0]}"
    [ -h "$path" -a "$(realpath "$path")" = /etc/drush ] ||
      sudo -Hu $user ln --backup --force --symbolic /etc/drush "$path"
  done
}