In Mac OS X, GitBash, and Linux you can use the three ssh- commands to create and manage your identities.
ssh-keygen Creates key pairs.
ssh-agent Agent for providing keys to remote servers. The agent holds loaded keys in memory.
ssh-add adds private key identities to the authentication agent

1. Adding your SSH Keys to an SSH Agent to Avoid Typing the Passphrase
eval $(ssh-agent)
ssh-add <private-key-file>

ssh-add

TODO

ssh-agent

1. Start the ssh-agent in the background
eval ”$(ssh-agent -s)“

ssh-keygen

https://www.digitalocean.com/community/tutorials/ssh-essentials-working-with-ssh-servers-clients-and-keys

1. generate an ssh key pair
ssh-keygen

2. generate an ssh key pair with larger number of bits
ssh keys are 2048 bits by default
ssh-keygen -b 4096

3. removing or changing passphrase on private key
ssh-keygen -p

4. displaying the ssh key fingerprint
ssh-keygen -l