YunoHost and all our apps are on the Git forge GitHub. Which means that if you want to work on an app, sooner or later you're going to have to deal with Git.
So let's see how to work with Git to be able to contribute in the context of YunoHost.
Branches are, as GitHub explains, "*a parallel version of a repository. It is contained within the repository, but does not affect the other branches. Allowing you to work freely without disrupting the "live" version.*"
The master branch is the branch that contains the version of the app users will actually install and use.
The usual thing to do is to work from the testing branch, and when everything is settled and tested, you can merge the testing branch in master, so users will enjoy the new release of your package.
If you don't have the permission to write on the repository, you will see (as on the picture) that you're going to create a fork (we'll see below what a fork is).
If you have the permission to write, you will just edit the file, without forking.
The first field is the name of your commit, a very short sentence to explain why you did this modification.
The second field is a large one for a more complete explanation, if you need it.
Finally, if you're editing a repository on which you have permission to write, you can either commit directly to the current branch or create a new branch.
It's usually better to create a new branch, that way you keep your modifications on a *parallel* version of the repository. Your modifications will be discussed in a pull request (explained below) then finally merged into the original branch.
But even if a fork is not the real repository, but just a copy, a fork is always linked to its parent. We'll see later that to create a fork is really useful when opening a pull request.
But, when you want to edit multiple files, the GitHub interface isn't really the best way. In such situation, you would rather clone the repository and work on a local repository.
You may still need to fork on your own account to be able to save your modifications if you don't have the permission on the distant repository.
After you have committed your changes, whether on a branch or a fork, you want to propose your modifications to be integrated into the main repository, or the original branch.
To do so, you're going to *create a pull request*. GitHub usually ask you directly if you want to do so.
When creating a pull request from a fork, to ease the work of the reviewers, **do never** uncheck the checkbox *Allow edits from maintainers*. That option simply allow the maintainers of the original repository to edit directly your work.
Following the [guide for packaging application within YunoHost](/packaging_apps_intro), your app has to be into the YunoHost-Apps organization, but if you have never contributed to an app before or never had any app into this organization you may not have the permission.
You have shockingly discovered that the wonderful app you love to use everyday does not yet have its YunoHost package. And because you're nice, you decided to create yourself the package, so everyone will enjoy that app the way you do.
The best is to start from the [example app](https://github.com/YunoHost/example_ynh). But as we have explained before, you don't want to fork, because if you do so, you're going to keep that link to the example app and it's really annoying.
`git clone` will download a copy of the repository. You will have the complete repository, with its branches, commits, and everything (into that apparently little `.git` directory).
*A side note though, if you expect to send your modifications back to the distant repository on GitHub, be sure to have the permission to write on this repository. Otherwise, fork before and clone your fork, on which you do have the permission.*
You do have your local copy of the repository, but because you have read carefully this documentation until then, you know that you should be sure to be on the testing branch before starting to work.
To see the branches, and to know on which you actually are, while into the directory of your repository, type `git branch`.
The current branch is highlighted and preceded by a `*`.
If it appears that you're not on the branch you wanted to be, or you're actually on master (which is bad !), you can move to another branch with `git checkout`
*Sometimes, you will encounter an impossible situation where Git is saying that you can't pull because you have local changes. But you don't care of those local modifications, you just want to get the last version of the distant branch. But Git don't care about what YOU want...*
To check the current status of your validation, you can use `git status`. It will show you which files will be included into your commit, and which files are modified, but not yet included.
`git status -v` will show also which part of the files are modified. A good way to be sure that you didn't make a mistake before committing.
Before committing, or after, or before starting to work. Whenever you feel like it !
You should consider adding your work to a separate branch, that way, it will be easy to create a pull request to merge into the testing branch and discuss with the other packagers what you suggest to change.
To create a new branch and move to this branch, you can use `git checkout -b my_new_branch`.
Your changes are validated, but only on your local clone of the repository. Now, you have to send those modifications back to the distant repository on GitHub.
In order to do that, you need to know what is your current branch. (If you don't know, `git branch` will give you that info).