配置SSH Keys到github，实现git clone 能力

clh899

　　问题：在机器没有配置git ssh keys 的时候，会出现一个错误：
　　Permission denied (publickey). fatal: The remote end hung up unexpectedly
　　配置步骤如下
Step 1: Check for SSH keys
　　First, we need to check for existing ssh keys on your computer. Open up Terminal andrun:
cd ~/.sshls# Lists the files in your .ssh directory　　Check the directory listing to see if you have a file named either id_rsa.pub or id_dsa.pub. If you don't have either of those files go to step2. Otherwise, you already have an existing keypair, and you can skip to step3.
Step2: Generate a new SSH key
　　To generate a new SSH key, enter the code below. We want the default
settings so when asked to enter a file in which to save the key, just
press enter.
ssh-keygen -t rsa -C "your_email@example.com"# Creates a new ssh key, using the provided email as a label# Generating public/private rsa key pair.# Enter file in which to save the key (/Users/you/.ssh/id_rsa): [Press enter]ssh-add id_rsa　　Now you need to enter a passphrase.
Whydo passphrases matter?
# Enter passphrase (empty for no passphrase): [Type a passphrase]# Enter same passphrase again: [Type passphrase again]　　Which should give you something like this:
# Your identification has been saved in /Users/you/.ssh/id_rsa.# Your public key has been saved in /Users/you/.ssh/id_rsa.pub.# The key fingerprint is:# 01:0f:f4:3b:ca:85:d6:17:a1:7d:f0:68:9d:f0:a2:db your_email@example.comStep3: Add your SSH key to GitHub
　　Run the following code to copy the key to your clipboard.
pbcopy < ~/.ssh/id_rsa.pub# Copies the contents of the id_rsa.pub file to your clipboard　　Alternatively, using your favorite text editor, you can open the ~/.ssh/id_rsa.pub fileand copy the contents of the file manually
　　Warning: it's important to copy the key exactly without adding newlinesor whitespace. Thankfully the pbcopycommand makes it easy to perform this setup perfectly.

• Goto your AccountSettings
  
  
• Click "SSHKeys" in the left sidebar
  
  
• Click"Add SSH key"
  
  
• Pasteyour key into the "Key" field
  
  
• Click"Add key"
  
  
• 　　Confirm the action by entering your GitHub password
  

Step4: Test everything out
　　To make sure everything is working you'll now SSH to GitHub. When you dothis, you will be asked to authenticate this action using your
password, which for this purpose is the passphrase you created earlier.
Don't change the git@github.com part.That's supposed to be there.
ssh -T git@github.com# Attempts to ssh to github　　You may see this warning:
# The authenticity of host 'github.com (207.97.227.239)' can't be established.# RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.# Are you sure you want to continue connecting (yes/no)?　　Don't worry, this is supposed to happen. Verify that the fingerprint matches the one here and type "yes".
# Hi username! You've successfully authenticated, but GitHub does not# provide shell access.　　If that username is correct, you've successfully set up your SSH key.
Don't worry about the shell access thing, you don't want that anyway.
　　If you see "access denied" please consider using HTTPS insteadof SSH. If you need SSH start attheseinstructions for diagnosing the issue.