在 OSX 中，可以以使用 ssh-add -K ~/.ssh/id_rsa 实现
参考 github 的帮助
Adding your SSH key to the ssh-agent
Before adding a new SSH key to the ssh-agent to manage your keys, you should have checked for existing SSH keys and generated a new SSH key.When adding your SSH key to the agent, use the default macOS
ssh-add command, and not an application installed by homebrew, or some other external source.
1.Start the ssh-agent in the background.
2.If you’re using macOS Sierra 10.12.2 or later, you will need to modify your
~/.ssh/config file to automatically load keys into the ssh-agent and store passphrases in your keychain.
3.Add your SSH private key to the ssh-agent and store your passphrase in the keychain. If you created your key with a different name, or if you are adding an existing key that has a different name, replace id_rsa in the command with the name of your private key file.
-K option is Apple’s standard version of
ssh-add, which stores the passphrase in your keychain for you when you add an ssh key to the ssh-agent.
If you don’t have Apple’s standard version installed, you may receive an error. For more information on resolving this error, see “Error: ssh-add: illegal option — K.”
4.Add the SSH key to your GitHub account.