Git - Online Repositories

Git - Online Repositories (e.g., GitHub)

Platforms like GitHub, GitLab, and Bitbucket provide web-based hosting for Git repositories, along with features for collaboration, issue tracking, and more. This section focuses on interacting with a GitHub repository using the command line.

Create a GitHub Repository

1. Go to GitHub.
2. Sign in to your account or create a new one.
3. Create a new repository by clicking the “New” button or the ’+’ icon in the navigation bar. Follow the on-screen instructions, giving your repository a name (e.g., my_first_repo). You can choose to initialize it with a README, .gitignore, and license.

Pushing an Existing Local Repository to GitHub

Tom has an existing local Git project and wants to host it on GitHub. First, he creates a new, empty repository on GitHub (e.g., named hello_world_project) without initializing it with a README, .gitignore, or license, as his local project already has its own history.

Tom has a local project with a hello.c file:

[tom@devbox ~]$ mkdir hello_world_project
[tom@devbox ~]$ cd hello_world_project/

[tom@devbox hello_world_project]$ echo '#include <stdio.h>
int main() {
  printf("Hello, Modern Git!\n");
  return 0;
}' > hello.c

[tom@devbox hello_world_project]$ gcc hello.c -o hello
[tom@devbox hello_world_project]$ ./hello

The above command will produce the following result:

Hello, Modern Git!

After verifying his code, he initializes a Git repository locally, adds, and commits his file:

[tom@devbox hello_world_project]$ git init -b main
Initialized empty Git repository in /home/tom/hello_world_project/.git/

[tom@devbox hello_world_project]$ git status -s
?? hello.c

[tom@devbox hello_world_project]$ git add hello.c

[tom@devbox hello_world_project]$ git status -s
A  hello.c

[tom@devbox hello_world_project]$ git commit -m "Initial commit with hello.c"

Next, he adds the GitHub repository URL (provided by GitHub when you create a new repository, e.g., https://github.com/yourusername/hello_world_project.git) as a remote named origin and pushes his main branch:

[tom@devbox hello_world_project]$ git remote add origin https://github.com/yourusername/hello_world_project.git

[tom@devbox hello_world_project]$ git push -u origin main

Authentication: When pushing to GitHub over HTTPS, Git will prompt for credentials. Instead of your password, you must use a Personal Access Token (PAT). You can generate a PAT from your GitHub account’s Developer settings. For SSH URLs (e.g., git@github.com:yourusername/hello_world_project.git), you’d use SSH keys. For more details, see GitHub’s documentation on PATs.

After successful authentication, the output will be similar to:

Enumerating objects: 3, done.
Counting objects: 100% (3/3), done.
Writing objects: 100% (3/3), 250 bytes | 250.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/yourusername/hello_world_project.git
 * [new branch]      main -> main
Branch 'main' set up to track remote branch 'main' from 'origin'.

Tom can now push any subsequent changes to this GitHub repository using git push.

Cloning a Repository from GitHub (Pull Operation)

Tom has successfully pushed his project to GitHub. Now, another developer, Jerry, can get a copy of this project.

Jerry creates a directory and clones the GitHub repository using its HTTPS URL:

[jerry@devbox ~]$ mkdir jerry_projects
[jerry@devbox ~]$ cd jerry_projects/

[jerry@devbox jerry_projects]$ git clone https://github.com/yourusername/hello_world_project.git

The above command produces output like:

Cloning into 'hello_world_project'...
remote: Enumerating objects: 3, done.
remote: Counting objects: 100% (3/3), done.
remote: Total 3 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (3/3), 250 bytes | 125.00 KiB/s, done.

He verifies the directory contents:

[jerry@devbox jerry_projects]$ ls
hello_world_project

[jerry@devbox jerry_projects]$ cd hello_world_project/
[jerry@devbox hello_world_project]$ ls
hello.c

Jerry now has a local copy and can start contributing. To get future updates from Tom, Jerry would use git pull inside his hello_world_project directory.