Could not open a connection to your authentication agent

执行ssh-add时出现Could not open a connection to your authentication agent

ssh-add ~/.ssh/id_rsa 提示如下图

执行$ ssh-agent.exe bash仍然提示Could not open a connection to your authentication agent
执行  eval `ssh-agent`  （是～键上的那个`） 
执行 ssh-add ~/.ssh/id_rsa

查看ssh-add -l