Git: Agent admitted failure to sign using the key. Permission denied (publickey).

已经配置完SSH keys后执行git clone时会报下面错误：

Agent admitted failure to sign using the key. 
Permission denied (publickey).

执行 ssh -T git@domain 时也会报这个错误，解决方法：
使用 ssh-add 命令把密钥添加到ssh-agent的高速缓存中：

 ssh-add   ~/.ssh/id_rsa 

注意：根据个人的密匙命名不同更改 id_rsa

参考：
Git: Agent admitted failure to sign using the key. Permission denied (publickey). fatal: Could …