Git Basics

Some Commands

• git clone: Clone a git repository
• git config --global user.name "Sanyika": Set username
• git config --global user.email "sanyika@gggmail.com": Set email
• git init: Initialize a local repository
• git add <file>: Add a file
• git status: Check current status
• git commit -m "My beautiful commit": Commit with a message
• git push: Push changes
• git pull: Pull changes, update local repository
• git branch <new_branch_name>: Create a new branch
• git checkout <branch_name>: Switch to a branch
• git checkout -- .: Discard all unstaged changes locally. In newer git versions, git restore . works similarly.
• git merge <branch_name>: Merge a branch into the current branch

Source: link

Terminology

• Local repository: The local working repository, e.g., ~/ros2_ws/src/my_repo
• Remote repository: Usually an online remote backup repository, e.g., github.com/my_name/my_repo

Preparations

If you haven't done so already, register on GitHub.

Using the Template

Navigate to https://github.com/sze-info/ros2_cpp_template.

Here, use the green button to create a package named my_awesome_package with your user:

Then you will see this page, where you need to fill in the repository name and click the green button to create the repository:

Clone Your Package with git clone

If your GitHub username is mycoolusername and the repository (and package) name is my_awesome_package, you can do it like this:

cd ~/ros2_ws/src

git clone https://github.com/mycoolusername/my_awesome_package

git clone https://github.com/horverno/my_awesome_package

Replace Everything in VS Code

cd ~/ros2_ws/src/my_awesome_package

code .

1. Replace ros2_cpp_template with my_awesome_package
2. Replace sze-info with mycoolusername
3. Replace todo as appropriate

Build

The package can now be built:

cd ~/ros2_ws/

colcon build --packages-select my_awesome_package

The terminal will return a message confirming that the my_awesome_package package has been built.

Run

Run in the usual way:

source ~/ros2_ws/install/local_setup.bash

ros2 launch my_awesome_package launch_example1.launch.py

Track Changes with git status

When we replaced the package name, several files were modified:

cd ~/ros2_ws/src/my_awesome_package

git status

Git status

The same in VS Code looks like this:

Git status in VS Code

Update Remote Repository with git push

We want to add all changes to the commit:

git add .

Fill in the commit message:

git commit -m "Initial commit of my_awesome_package"

Actually push the changes to GitHub servers:

git push

Git status after add

In VS Code, this is simpler: Commit, then Sync Changes:

Git status Sync (push)

Update Local Repository with git pull

In case the local version is not the latest, the remote stored on GitHub can be updated:

Git status (pull)

Sources

• docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Creating-Your-First-ROS2-Package.html
• docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Cpp-Publisher-And-Subscriber.html
• docs.ros.org/en/humble/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Py-Publisher-And-Subscriber.html