Git: add vs push vs commit

Question

1. git add adds your modified files to the queue to be committed later. Files are not committed

2. git commit commits the files that have been added and creates a new revision with a log... If you do not add any files, git will not commit anything. You can combine both actions with git commit -a

3. git push pushes your changes to the remote repository.

This figure from this git cheat sheet gives a good idea of the work flow

git add isn't on the figure because the suggested way to commit is the combined git commit -a, but you can mentally add a git add to the change block to understand the flow.

Lastly, the reason why push is a separate command is because of git's philosophy. git is a distributed versioning system, and your local working directory is your repository! All changes you commit are instantly reflected and recorded. push is only used to update the remote repo (which you might share with others) when you're done with whatever it is that you're working on. This is a neat way to work and save changes locally (without network overhead) and update it only when you want to, instead of at every commit. This indirectly results in easier commits/branching etc (why not, right? what does it cost you?) which leads to more save points, without messing with the repository.

git add selects changes

git commit records changes LOCALLY

git push shares changes

• git add adds files to the Git index, which is a staging area for objects prepared to be commited.
• git commit commits the files in the index to the repository, git commit -a is a shortcut to add all the modified tracked files to the index first.
• git push sends all the pending changes to the remote repository to which your branch is mapped (eg. on GitHub).

In order to understand Git you would need to invest more effort than just glancing over the documentation, but it's definitely worth it. Just don't try to map Git commands directly to Subversion, as most of them don't have a direct counterpart.

I find this image very meaningful :

(from : Oliver Steele -My Git Workflow (2008) )

I was confused about what 'add' really does. I just read a very enlightening paragraph from the book Git Pro that I'd like to add here, because it clarifies things

It turns out that Git stages a file exactly as it is when you run the git add command. If you commit now, the version of benchmarks.rb as it was when you last ran the git add command is how it will go into the commit, not the version of the file as it looks in your working directory when you run git commit. If you modify a file after you run git add, you have to run git add again to stage the latest version of the file

Excerpt From: Chacon, Scott. “Pro Git.” Springer, 2009-08-19T00:00:00+00:00. iBooks. This material may be protected by copyright.

add tells git to start tracking a file.

commit commits your current changes on your local repository

push pushes you local repo upstream.