Git merge after fetch - how, exactly?

I've read from various sources that it's usually a better idea to fetch then merge rather than simply pull as it allows for finer control. That said, I've yet to find actually how to do it. Case in point:

There was a small change made to some of the code in one of my GitHub repository's master branch. I was able to fetch it, but I don't know how to actually merge the differences in with my local master branch. git branch lists all of the local branches I have, but nothing indicating anything to merge to.

So, is it just something like git merge master or git merge origin/master? What am I missing?

git merge origin/master should work. Since master is usually a tracking branch, you could also do git pull from that branch and it will do a fetch & merge for you.

If you have local changes on your master that aren't reflected on origin, you might want git rebase origin/master to make sure your commits are 'on top'.

I typically do this:

git merge --ff-only @{u}

Which says, "only do a fast-forward merge from the upstream tracking branch." It's nice because if it fails, then I know I introduced something on master that is not upstream. I have that aliased to ff, just to make it easier to type.

If there are changes, and you simply want to merge them, you can do:

git merge @{u}

Which will merge in the upstream branch. However, if you'd like a cleaner history (and avoid the "Merging 'origin/master' into 'master'" commits, then you might want to consider rebasing instead:

git rebase @{u}

Of course, you can you origin/master instead of @{u} in any of these examples.

The command

git pull $some_url

is equivalent to

git fetch $some_url
git merge FETCH_HEAD

See also the git-pull(1) man page for details, especially the first two paragraphs of the description.