diff branch changes in git relative to common ancestor

If you are going to check the current branch against where you branch off, just add .... So the command would look like

git diff master...

It's the same as git diff master...HEAD. I am running git version 2.17.1. This might behave differently in an older version.

After extensively looking at git help rev-parse and experimenting around, I found this piece of information:

   <rev1>..<rev2>
       Include commits that are reachable from <rev2> but exclude those
       that are reachable from <rev1>. When either <rev1> or <rev2> is
       omitted, it defaults to HEAD.

   <rev1>...<rev2>
       Include commits that are reachable from either <rev1> or <rev2>
       but exclude those that are reachable from both. When either <rev1>
       or <rev2> is omitted, it defaults to HEAD.

Somehow I was always under the impression, that master..branch is what I need and forgot about master...branch (with three dots).

But experimenting with it showed, that the three-dot notation is exactly what I'm looking for:

$ git diff master...branch

shows only the differences of branch relative to where it took off of master.

What I'm looking for is basically a nicer way to run

$ git diff $(git merge-base master branch)..branch

How about creating an alias?

git config alias.diffbr '!f() { git diff $(git merge-base master $1)..$1; }; f'

Then you can simply do git diffbr branch.

If you want the alias to be available for all repositories on your machine add the --global argument to git config.

I know this is not the answer you're looking for here, but it might help someone else. Using a graphical tool like gitk, you can:

• Open gitk
• Click on H, right click and select "Mark this commit"
• Click on B, right click and select "Diff this -> marked commit"

Now you see all updated files to the right, and all the modified lines (per file) to the left.