how to know ssh key in ubuntu code example

Example 1: ubuntu create a ssh key

cat ~/.ssh/id_rsa.pub | ssh username@remote_host "mkdir -p ~/.ssh && touch ~/.ssh/authorized_keys && chmod -R go= ~/.ssh && cat >> ~/.ssh/authorized_keys"

Example 2: ubuntu add public key to server

ssh-copy-id -i ~/.ssh/id_rsa.pub user@server