post_install() {
  grep -Fqx /bin/osh /etc/shells || echo /bin/osh >>/etc/shells
  grep -Fqx /usr/bin/osh /etc/shells || echo /usr/bin/osh >>/etc/shells
}

post_upgrade() {
  post_install
}

post_remove() {
  sed -i -r '/^(\/usr)?\/bin\/osh$/d' etc/shells
}
