Copy content of SSH public key.
cat ~/.ssh/id_rsa.pub
or
sudo apt-get install xclipxclip -sel clip < ~/.ssh/id_rsa.pub
Copy/Install local public key to remote server
ssh-copy-id USERNAME@SERVER_IP
or
ssh-copy-id -i KEY_FILE_NAME ln-user@SERVER_IP
NOTE: ssh-copy-id
ssh-copy-id installs an SSH key on a server as an authorized key. Its purpose is to provision access without requiring a password for each login. This facilitates automated, passwordless logins and single sign-on using the SSH protocol.