Lists the files in your .ssh directory, if they exist

like ls: /Users/eddy/.ssh: No such file or directory 则没有ssh key

生成新的ssh key
第一步：生成public/private rsa key pair
在命令行中输入ssh-keygen -t rsa -C "your_email@example.com"

或者ssh-keygen -t rsa

默认会在相应路径下（/your_home_path）生成id_rsa和id_rsa.pub两个文件，如下面代码所示

ssh-keygen -t rsa -C "your_email@example.com"# Creates a new ssh key using the provided emailGenerating public/private rsa key pair.
Enter file in which to save the key (/your_home_path/.ssh/id_rsa):

第二步：输入passphrase（本步骤可以跳过）

设置passphrase后，进行版本控制时，每次与GitHub通信都会要求输入passphrase，以避免某些“失误”

Enter passphrase (empty for no passphrase): [Type a passphrase]

Enter same passphrase again: [Type passphrase again]

第三步：将新生成的key添加到ssh-agent中:

start the ssh-agent in the backgroundeval "$(ssh-agent -s)"Agent pid 59566ssh-add ~/.ssh/id_rsa

测试：
eddytekiMBP:~ eddy$ eval "$(ssh-agent -s)"
Agent pid 1871
eddytekiMBP:~ eddy$ ssh-add ~/.ssh/id_rsa
Identity added: /Users/eddy/.ssh/id_rsa (/Users/eddy/.ssh/id_rsa)
eddytekiMBP:~ eddy$

将ssh key添加到GitHub中
用自己喜欢的文本编辑器打开id_rsa.pub文件，里面的信息即为SSH key，将这些信息复制到GitHub的Add SSH key页面即可

不同的操作系统，均有一些命令，直接将SSH key从文件拷贝到粘贴板中，如下：

mac

pbcopy < ~/.ssh/id_rsa.pub# Copies the contents of the id_rsa.pub file to your clipboard
windows

clip < ~/.ssh/id_rsa.pub# Copies the contents of the id_rsa.pub file to your clipboard
linux

sudo apt-get install xclip# Downloads and installs xclip. If you don't have apt-get, you might need to use another installer (like yum)xclip -sel clip < ~/.ssh/id_rsa.pub# Copies the contents of the id_rsa.pub file to your clipboard

ssh-keygen -f "~/.ssh/known_hosts" -R 192.168.1.254