如何克隆GitHub仓库并推送到GitLab？及执行git remote add命令时出现“fatal: not a git repository”错误的问题咨询

Hey there! Let's work through both your questions: first resolving that frustrating Git error, then walking through the full process of cloning a GitHub repo and pushing it to GitLab.

Why You're Getting the "fatal: not a git repository" Error #

That error pops up for two key reasons in your case:

1. You're not in a Git repository directory: The git remote add command only works inside a folder that has a .git subfolder (i.e., a directory initialized with Git or cloned from a repo). You tried running the command in a regular folder, so Git couldn't find the repository files it needs.
2. You used a repository ID instead of a URL: The 123456789 from the meta tag is an internal GitHub ID—not the clone URL Git requires. You need to use the actual HTTPS or SSH URL of the repository (you can copy this from the "Code" button on the GitHub repo page).

Quick Fix for the Error #

If you haven't already cloned the GitHub repo, start with this:

# Clone the GitHub repo to your local machine
git clone https://github.com/[your-github-username]/[repo-name].git

# Navigate into the cloned repo directory (this is now a Git repo!)
cd [repo-name]

Now you can safely run git remote add commands inside this directory, using the proper repository URL instead of the ID.

Full Steps to Clone GitHub Repo & Push to GitLab #

Follow these steps to move your repo over completely:

1. Clone the GitHub repository locally
   Use the command above to pull the repo to your computer. This ensures you have all branches, commits, and files locally.

2. Create an empty repository on GitLab

   • Go to GitLab and create a new project.
   • Do NOT initialize it with a README, .gitignore, or license—leave it completely empty. This avoids merge conflicts when pushing your existing repo.

3. Add GitLab as a remote repository
   Inside your local repo directory, run this command (replace the URL with your new GitLab repo's clone URL):

   git remote add gitlab https://gitlab.com/[your-gitlab-username]/[new-gitlab-repo-name].git
   

   Here, gitlab is just a friendly name for the remote—you can use any name except origin (which is already linked to GitHub by default).

4. Push all content to GitLab

   • Push your main branch first (replace main with master if that's your default branch):

     git push gitlab main
     

   • To push all branches (so every branch from GitHub is copied to GitLab):

     git push --all gitlab
     

   • To push all tags (if your repo has release tags):

     git push --tags gitlab
     

5. (Optional) Switch your default remote to GitLab
   If you want to use GitLab as your primary repo going forward:

   # Rename the GitHub remote to something like "github" (optional but helpful)
   git remote rename origin github
   
   # Rename the GitLab remote to "origin" (the default name Git uses)
   git remote rename gitlab origin
   

   Now when you run git push or git pull, it will default to GitLab instead of GitHub.

内容的提问来源于stack exchange，提问作者Rashi