很久没用的树莓派。更新时出现的问题：

```bash $ sudo apt-get update Err:1 http://raspbian.raspberrypi.org/raspbian buster InRelease Temporary failure resolving 'raspbian.raspberrypi.org' Err:2 http://archive.raspberrypi.org/debian buster InRelease Temporary failure resolving 'archive.raspberrypi.org' Reading package lists… Done W: Failed to fetch http://raspbian.raspberrypi.org/raspbian/dists/buster/InRelease Temporary failure resolving 'raspbian.raspberrypi.org' W: Failed to fetch http://archive.raspberrypi.org/debian/dists/buster/InRelease Temporary failure resolving 'archive.raspberrypi.org' W: Some index files failed to download. They have been ignored, or old ones used instead. ```

通过([src](https://askubuntu.com/a/91595))：

```bash echo "nameserver 8.8.8.8" | sudo tee /etc/resolv.conf > /dev/null ```

解决。