【ASK】git使用中出现Permission denied (publickey).

好久没有用git了，今天突然执行了一下

$git submodule update --init --recursive

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结果出现如下提示

Cloning into 'Submodules/********'...

Permission denied (publickey).

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由于确实好长时间没有摸过git了，一点印象都没有了。没办法，只能google了，还好一搜就得到一片经典官方帮助：

https://help.github.com/articles/generating-ssh-keys/

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Generating SSH keys

SSH keys are a way to identify trusted computers, without involving passwords. The steps below will walk you through generating an SSH key and adding the public key to your GitHub account.

We recommend that you regularly review your SSH keys list and revoke any that haven't been used in a while.

Tip: GitHub has a Mac client! You can use it without ever touching the command line.

Step 1: Check for SSH keys

First, we need to check for existing SSH keys on your computer. Open Terminal and enter:

ls -al ~/.ssh

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

Check the directory listing to see if you already have a public SSH key. By default, the filenames of the public keys are one of the following:

id_dsa.pub
id_ecdsa.pub
id_ed25519.pub
id_rsa.pub

Tip: If you receive an error that the ~/.ssh doesn't exist,, don't worry! We'll create it in Step 2.

Step 2: Generate a new SSH key

With Terminal still open, copy and paste the text below. Make sure you substitute in your GitHub email address.

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.

We strongly suggest keeping the default settings as they are, so when you're prompted to "Enter a file in which to save the key", just press Enter to continue.
```
# Enter file in which to save the key (/Users/you/.ssh/id_rsa): [Press enter]
```
You'll be asked to enter a passphrase.
```
# Enter passphrase (empty for no passphrase): [Type a passphrase]

# Enter same passphrase again: [Type passphrase again]
```
Tip: We strongly recommend a very good, secure passphrase. For more information, see "Working with SSH key passphrases".

After you enter a passphrase, you'll be given the fingerprint, or id, of your SSH key. It will look 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.com

Step 3: Add your key to the ssh-agent

To configure the ssh-agent program to use the SSH key you've generated:

Ensure ssh-agent is enabled:

# start the ssh-agent in the background

eval "$(ssh-agent -s)"

# Agent pid 59566

Add your generated SSH key to the ssh-agent:
```
ssh-add ~/.ssh/id_rsa
```

Step 4: Add your SSH key to your account

To configure your GitHub account to use your SSH key:

Copy the SSH key to your clipboard. Keep in mind that your key may also be named id_dsa.pub,id_ecdsa.pub or id_ed25519.pub, in which case you must change the filename as follows:

pbcopy < ~/.ssh/id_rsa.pub

# Copies the contents of the id_rsa.pub file to your clipboard

Warning: It's important to copy the key exactly without adding newlines or whitespace.

Add the copied key to GitHub:

In the top right corner of any page, click .
In the user settings sidebar, click SSH keys.
Click Add SSH key.
In the Title field, add a descriptive label for the new key. For example, if you're using a personal Mac, you might call this key "Personal MacBook Air".
Paste your key into the "Key" field.
Click Add key.
Confirm the action by entering your GitHub password.

Step 5: Test the connection

To make sure everything is working, you'll now try to SSH into . When you do this, you will be asked to authenticate this action using your password, which is the SSH key passphrase you created earlier.

Open Terminal and enter:

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)?

Verify the fingerprint in the message you see matches the following message, then type yes:

# Hi username! You've successfully authenticated, but GitHub does not

# provide shell access.

If the username in the message is yours, you've successfully set up your SSH key!

If you receive a message about "access denied," you can read these instructions for diagnosing the issue.

If you're switching from HTTPS to SSH, you'll now need to update your remote repository URLs. For more information, see Changing a remote's URL.

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讲的十分详细，再次感谢一下，一步一步安装文档所说进行，竟然意外的发现以前就在自己的github上已经做过类似的操作了。难道真是上了岁数，忘得一干二净......