Just fix the sudo apt-get update errors and warnings

I often do sudo apt-get update when using linux, but I often get warnings. This time the cleaning

If it increases again, it may be irritating (2020/05/16)

Two this time

E: The repository 'http://ppa.launchpad.net/kazam-team/unstable-series/ubuntu bionic Release' does not have a Release file.

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://nvidia.github.io/nvidia-docker/ubuntu18.04/amd64  InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6ED91CA3AC1160CD

Since it is difficult to see the top, I will also post plain text ↓

E: The repository 'http://ppa.launchpad.net/kazam-team/unstable-series/ubuntu bionic Release' does not have a Release file.

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://nvidia.github.io/nvidia-docker/ubuntu18.04/amd64 InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6ED91CA3AC1160CD

Solution 1

The public key has expired, so I'll update it.

See also: https://linuxconfig.org/how-to-list-and-remove-ppa-repository-on-ubuntu-18-04-bionic-beaver-linux

Solution 2

I'll delete the repository of the ppa file.

 sudo apt-add-repository -r ppa:kazam-team/unstable-series

See also: https://linuxconfig.org/how-to-list-and-remove-ppa-repository-on-ubuntu-18-04-bionic-beaver-linux