apt update时报错E: The repository 'http://dell.archive.canonical.com focal InRelease' is not signed.怎么处理？

当你遇到`apt update`报错"The repository 'http://dell.archive.canonical.com focal InRelease' is not signed."的问题时，这通常是因为你尝试更新的Dell官方软件仓库的公钥未被你的系统信任。为了解决这个问题，你需要添加该仓库的公钥以验证其内容。以下是步骤：

1. **打开终端**：按下Ctrl + Alt + T快捷键打开终端。

2. **获取公钥**：

   sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <KEY>

将 `<KEY>` 替换为实际的公钥ID，你可以从Dell的官方文档或网站上找到这个ID。

3. **添加存钥文件**：

   echo "deb http://dell.archive.canonical.com focal main restricted universe multiverse" | sudo tee /etc/apt/sources.list.d/dell.list > /dev/null

4. **刷新源列表**：

   sudo apt update

5. **如果还是失败，检查网络连接**：确保你的设备可以访问互联网，并确认DNS设置正常。

完成上述操作后，你应该能够成功地更新你的软件包。如果你仍然遇到问题，可能需要检查防火墙设置或者其他网络限制。

相关问题

W: http://archive.ubuntu.com/ubuntu/dists/jammy/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: http://archive.ubuntu.com/ubuntu/dists/jammy/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: GPG error: http://archive.ubuntu.com/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C E: The repository 'http://archive.ubuntu.com/ubuntu jammy InRelease' is not signed. W: http://security.ubuntu.com/ubuntu/dists/jammy-security/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: http://security.ubuntu.com/ubuntu/dists/jammy-security/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: GPG error: http://security.ubuntu.com/ubuntu jammy-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C E: The repository 'http://security.ubuntu.com/ubuntu jammy-security InRelease' is not signed. W: http://archive.ubuntu.com/ubuntu/dists/jammy-updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: http://archive.ubuntu.com/ubuntu/dists/jammy-updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: GPG error: http://archive.ubuntu.com/ubuntu jammy-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C E: The repository 'http://archive.ubuntu.com/ubuntu jammy-updates InRelease' is not signed. W: http://archive.ubuntu.com/ubuntu/dists/jammy-backports/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: http://archive.ubuntu.com/ubuntu/dists/jammy-backports/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg are ignored as the file is not readable by user '_apt' executing apt-key. W: GPG error: http://archive.ubuntu.com/ubuntu jammy-backports InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C E: The repository 'http://archive.ubuntu.com/ubuntu jammy-backports InRelease' is not signed. E: Problem executing scripts APT::Update::Post-Invoke 'rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true' E: Sub-process returned an error code

这个错误是由于apt-key无法读取/etc/apt/trusted.gpg.d/目录下的文件，导致无法验证Ubuntu软件源的签名。解决这个问题的方法是：

1. 使用以下命令导入缺失的公钥：

   sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 871920D1991BC93C

注意替换上述命令中的871920D1991BC93C为您的错误中所提到的缺失的公钥。

2. 如果上述命令无效，可以尝试使用以下命令：

   sudo apt-key adv --refresh-keys --keyserver keyserver.ubuntu.com

3. 如果上述命令仍然无效，可以尝试手动下载公钥并导入。首先，找到缺失的公钥的ID，例如871920D1991BC93C。然后，使用以下命令下载公钥：

   sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 871920D1991BC93C

最后，使用以下命令将公钥导入系统：

   sudo apt-key add /path/to/downloaded/key

注意替换上述命令中的/path/to/downloaded/key为您下载的公钥文件的路径。

完成上述步骤后，再次运行apt-get update应该就不会出现上述错误了。