How to detect differences between local repo and remote repo in git?

Question

Say I did a git clone from a url for a repository. I made some changes to a file, did a git commit.

When I do a git pull, I see that it says \"Already up-to-date\"

Answer 1

My first advice is to not git pull. Do a git fetch followed by a git merge.

To answer your zero'th question: In fact, you are up-to-date. You have all the commits that the remote repository has. So, there is nothing left to fetch or merge¹.

To answer your first question:

1. git commit: commit your changes on your own branch, totally unrelated to what's going on in remote repositories.
2. git fetch origin: get the contents of the remote repository (origin), but keep them under origin/branch branches. Your own code is unaffected at this point.
3. git merge origin/master: merge origin/master which is the master branch of the remote repository origin (which you fetched just now) with your current branch.
4. git push origin: push back the commit and the merge to the remote repository

To answer your second question:

1. git fetch origin: update origin/branch branches.
2. git diff origin/master: get the difference between your current branch and the branch origin/master.

---

¹ Suppose this is what the commits in your repository initially look like, on branch master:

A -> B -> C -> D -> E
                    |
                    |\- master
                    |
                     \- origin/master

This is right after you cloned the repository. Now you say you have made a new commit on your local branch master:

A -> B -> C -> D -> E -> F
                    |    |
                    |     \- master
                    |
                     \- origin/master

So there are two things to observe here.

1. Assuming no activity by somebody else in the remote origin, there is nothing new to fetch. So git fetch origin master tells you there is nothing new.

2. If you do git merge origin/master, again, there is nothing to merge. origin/master is a prefix of master. In other words, master already contains all the commits that origin/master has, so there is nothing new to merge.

If you had used fetch and merge instead of pull, you could easily understand which part of the double-command (pull) is the one that results in unexpected (in your opinion) behavior.

Of course, after a git push origin master, you will get:

A -> B -> C -> D -> E -> F
                         |
                         |\- master
                         |
                          \- origin/master