Difference between git merge master and origin/master?

Question

Result of the command git merge origin/master:

javanoob@DELL:~/workspace/PROJECT_One$ git merge origin/master 
Updating d83ef9c..dd520ea
error: The following untracked working tree files would be overwritten by merge:
    sample.txt
Please move or remove them before you can merge.
Aborting

Result of the command git merge master:

javanoob@DELL:~/workspace/PROJECT_One$ git merge master
Already up-to-date.

When I do the command git merge origin/master It shows that there are some files which will be overwritten but if I do the same command without the prefix origin/ it says everything is already up-to-date.

What is wrong in this setup?

I don't know if it matters but before running these commands, I did run the command git fetch origin

Answer 1

git fetch fetches information on remote branches, but does not make any changes to your local master branch. Because of this, master and origin/master are still diverged. You'd have to merge them by using git pull.

When you make a commit, your local master branch is ahead of origin/master until you push those changes. This case is the opposite, where the origin/master branch is ahead of your local master branch. This is why you are getting different outcomes.

Read https://stackoverflow.com/a/7104747/2961170 for more information.

Answer 2

Using git merge origin/master refers to the master branch on the server. git merge master refers to your local master branch.

By using git pull you can merge them if they diverge.