1.查看是否已经有了ssh密钥：cd ~/.ssh
如果没有密钥则不会有此文件夹，有则备份删除
2.生存密钥：
$ ssh-keygen -t rsa -C "邮箱"
按3个回车，密码为空。
Your identification has been saved in /home/tekkub/.ssh/id_rsa.
Your public key has been saved in /home/tekkub/.ssh/id_rsa.pub.
The key fingerprint is:
………………
最后得到了两个文件：id_rsa和id_rsa.pub
id_rsa是RSA PRIVATE KEY，id_rsa.pub是公钥