在ubuntu20中安装了docker，然后docker search 、docker pull命令一直提示：
Error response from daemon: Get "https://registry-1.docker.io/v2/": x509: certificate signed by unknown authority
后来发现是证书问题导致的，解决如下：
apt install ca-certificates
update-ca-certificates -f
#会如下显示：
root@zbs:/usr/share# update-ca-certificates -f
Clearing symlinks in /etc/ssl/certs...
done.
Updating certificates in /etc/ssl/certs...
128 added, 0 removed; done.