how to manually add ssh key code example

Example 1: ssh add new key

$ eval "$(ssh-agent -s)"
> Agent pid 59566

Example 2: add ssh key to server

Generate ssh keys (Skip this step if you already have one).
To generate new RSA keys, enter this on the command line.
ssh-keygen -t -rsa
Follow the prompts. You do not need to enter a file name but you should enter a password to make your key more secure. The default file name is id_rsa.pub . By default the key file is saved at ~/.ssh/id_rsa.pub .
Copy your public keys to the remote server.
scp ~/.ssh/id_rsa.pub user@your_ip:/
Add your public key to the authorized keys file on remote server
To add you keys to the file, you can use the following command:
cat ~/id_rsa.pub >> ~/.ssh/authorized_keys

If you do not have the folder ~/.ssh/authorized_keys , you can create this with the following commands:
mkdir -p ~/.ssh
touch ~/.ssh/authorized_keys
Restart server for key changes to take effect