Could not execute ‘apt-key‘ to verify signature (is gnupg installed?)

所有答案都是：

因为tmp 文件夹权限不够

chmod 777 /tmp

apt-get update --allow-unauthenticated

然而没用，后在bing中找到答案

sudo apt-get clean
sudo mv /var/lib/apt/lists /tmp
sudo mkdir -p /var/lib/apt/lists/partial
sudo apt-get clean
sudo apt-get update