addendum-01-gitignore.md

The .DS_Store file in MacOS

If you are a Mac user, you may have noticed that your computer sometimes creates files called .DS_Store which are visible when you run ls -a or git status.

What are these files?

Mac creates the .DS_Store files in each folder to store information about how the icons in that folder should be displayed. It is a hidden folder (becuase it starts with a .) which means that it doesn't appear in the finder, or when you run an ls, but it is there. You can see it by running ls -a.

Why do i care?

The .DS_Store file can cause conflicts if they end up in your git repository, especially when you're working on a project with other mac users.

What should I do?

Try not to commit .DS_Store files to your GitHub repos.

Here is one way to make sure git always ignores the .DS_Store file so that you remove the possibility of accidentally committing it to a repo.

One member of your team can create a file called .gitignore, which tells git to ignore certain files or file types.

1. cd into the folder containing your project (the folder must be a git repository). Make sure you're on the master branch and that all changse so far have been committed. git status should show the staging area is empty.

2. Add the .gitignore file

   touch .gitignore
   echo ".DS_Store" > .gitignore
   git add .gitignore
   git commit -m "make git ignore .DS_Store files"
   git push
   

That's it. Git will now always ignore the .DS_Store file in that repository.