我不想再补充另一个答案，但我的特定场景在这里没有完全涵盖。我有一个本地回购，其中有我想保存的更改历史，还有一个在Github上为我创建的非空回购(即默认的README.md)。是的，你总是可以将Github回购重新创建为空回购，但在我的情况下，其他人有权限创建这个特定的回购，如果有一个简单的解决方案，我不想麻烦他。

在这种情况下，当你在设置远程源后尝试git push时，你会遇到这个错误:

 ! [rejected]        master -> master (fetch first)
error: failed to push some refs to 'git@github.com:<my repo>.git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

正如错误所示，我需要在设置远程原点后执行git拉取，但我需要指定——allow-unrelated-histories选项。如果没有这个选项，git pull会发出警告:没有共同提交。

下面是对我有效的命令序列:

git remote add origin <github repo url>
cp README.md README.md-save
git pull origin master --allow-unrelated-histories
mv README.md-save README.md
git commit -a
git push

这个对我来说很有用(需要的时候留作参考)

# Go into your existing directory and run below commands
cd docker-spring-boot
echo "# docker-spring-boot" >> README.md
git init
git add -A
git commit -m "first commit"
git branch -M master
git remote add origin https://github.com/devopsmaster/docker-spring-boot.git
git push -u origin master
                

截至2019年7月29日，Github向用户提供了在创建回购时完成这项任务的说明，并提供了几个选项:

在命令行上创建一个新的存储库

git init
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/user/repo.git
git push -u origin master

从命令行推送现有存储库

git remote add origin https://github.com/user/repo.git
git push -u origin master

从其他存储库导入代码

按导入按钮初始化进程。

对于视觉学习者来说:

从命令行导航到本地存储库目录。 在GitHub中创建一个新的存储库，它将为你提供一个以.git结尾的链接。 在cmd中运行:git remote add origin [your_GitHub_Repository_link](记住链接应该以.git结尾) 然后执行命令git push -u origin master

希望这对你有用。

我知道，这是一个老问题，但我试图解释每一步，所以它可以帮助别人。这是我如何添加一个现有的源代码到git:

Create the repo on the git, so you'll have the ssh || https where you're gonna remote add you source code. In your terminal go to the path of your project. Run git init (here you initiate the project as a git one). Run git add * (here you add all the files and folders from you project). Run git commit -m "Initial Commit." (here you commit your files and folders added in step #4; keep in mention that you can't push your changes without committing them). Run git remote add origin https://your_username@bitbucket.org/your_username/project-name.git (here you add a remote project where your source it's gonna be pushed; replace my link with your ssh || https from the step #1). Run git push -u origin master (here you push your source into the git repository).

注意:这些都是将源代码推入主分支的简单步骤。

如果你用的是Mac(这可能在PC上也一样)，这里有一个非常简单的方法来做到这一点。奇怪的是，我到处寻找这个简单的方法，但始终没有找到。

Do not do anything on Github (other than having an account, and not having used up all your available repos). Download GitHub for Mac and install. Go through the account setup, etc. Do NOT create any repositories for your existing project. "Add New Local Repository" in repositories. Select your existing folder. It'll ask if you want to do that, say yes. Once done, you'll see a list of all your files, etc. Commit them. Go to Repositories and Publish (this will create the new repo on GitHub for you, if you set up your account properly). Go to Repositories and Push (you'll either see the "nothing to push" thing, or it'll push your files/changes to the newly-auto-made repo). Wonder why you could not find this simple process anywhere else.

我知道不建议使用项目文件夹作为回购文件夹。我一直这样做，它总是有效的，它使它变得简单，而且我从来没有遇到过任何麻烦。