步骤1：Generating a new SSH key
$ ssh-keygen -t rsa -b 4096 -C "your_email@example.com"> Enter file in which to save the key (/Users/lr/.ssh/id_rsa): /Users/your/.ssh/github.com/your/id_rsa
> Enter passphrase (empty for no passphrase): [Press enter]
> Enter same passphrase again: [Press enter]
Your identification has been saved in /Users/your/.ssh/github.com/your/id_rsa.
Your public key has been saved in /Users/your/.ssh/github.com/your/id_rsa.pub.
步骤2：Adding your SSH key to the ssh-agent
$ ssh -T git@github.comPermission denied (publickey).
$ ssh -vT git@github.comOpenSSH_7.7p1, LibreSSL 2.7.3
$ ssh-add -K /Users/your/.ssh/github.com/your/id_rsaIdentity added: id_rsa (id_rsa)
$ ssh -T git@github.comHi your! You've successfully authenticated, but GitHub does not provide shell access.
步骤3：Adding your SSH key to GitHub.com
登录：github.com
打开：settings > SSH and GPG keys
将公钥id_rsa.pub ( /Users/your/.ssh/github.com/your/id_rsa.pub ) 拷贝至New SSH Key中。
步骤4：Using SourceTree to access repositories of GitHub.com
在github.com新建远程仓库，用SourceTree克隆代码，然后修改代码，最后推送到远程仓库。
如果成功，则证明一切符合预期；
如果不成功，则根据具体情况进行调整。
常见问题：
SSH权限问题：Permissions 0644 for '/Users/your/.ssh/id_rsa' are too open.
chmod 0600 /Users/your/.ssh/id_rsa
GIT模式问题：使用了gitlab远程仓库的http地址，导致无权限推送新代码至远程仓库。
在SourceTree将克隆的本地仓库转换成SSH，再执行远程发布。
温馨提示：
同一个github账号，可以使用不同的ssh密钥以对应不同的仓库需要。
所以，当你将远程仓库克隆为本地仓库后，应及时对本地仓库进行自定义配置：
> 用户信息（用户名和邮件）
> .gitignore文件（忽略的文件和文件夹）
在本地仓库目录下执行命令：git config --list，可以查看当前仓库的配置信息
