Re: How to Install postgresql-client-11 on Ubuntu 18.04?

I have been, yes, but looking more closely, getting some ignores and errors, here's a shortened output of it:
sudo apt update | grep postgres

WARNING: apt does not have a stable CLI interface yet. Use with caution in scripts.

Ign http://apt.postgresql.org trusty-pgdg InRelease
Ign http://apt.postgresql.org trusty-pgdg Release.gpg
Ign http://apt.postgresql.org trusty-pgdg Release
Err http://apt.postgresql.org trusty-pgdg/main amd64 Packages
Ign http://apt.postgresql.org trusty-pgdg/main Translation-en_US
Ign http://apt.postgresql.org trusty-pgdg/main Translation-en
W: GPG error: http://repo.percona.com trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9334A25F8507EFA5
W: Failed to fetch http://apt.postgresql.org/pub/repos/apt/dists/trusty-pgdg/main/binary-amd64/Packages  404  Not Found [IP: 217.196.149.55 80]

E: Some index files failed to download. They have been ignored, or old ones used instead.