ssh-add adds private key identities to the authentication agent
ssh-agent. For example ,while using git under linux , we can add ssh private key into github so that we can enable SSO .
ssh-add depends on
ssh-agent which means
ssh-agent service needs to be running while running
ssh-add , if below error been showed then it means somehow you don’t have
ssh-agent running .
$ ssh-add .ssh/id_ed25519 Error connecting to agent: Connection refused
$ eval "$(ssh-agent -s)"
$ eval `ssh-agent -c`
Now you should be able to add your SSH private key to the ssh-agent successfully.