$ curl http://archive.ubuntu.com/ubuntu/project/ubuntu-archive-keyring.gpg.sigs 2>/dev/null | gpg --no-default-keyring --keyring /usr/share/keyrings/ubuntu-master-keyring.gpg --output /etc/apt/trusted.gpg.d/ubuntu-archive-netupdate.gpg --decrypt
$ curl http:// archive. ubuntu. com/ubuntu/ project/ ubuntu- archive- keyring. gpg.sigs 2>/dev/null | gpg --no-default- keyring --keyring /usr/share/ keyrings/ ubuntu- master- keyring. gpg --output /etc/apt/ trusted. gpg.d/ubuntu- archive- netupdate. gpg --decrypt