What is the difference between double dot and triple dot for git log

Question

I want to get the changes between commit A and B. Basically what changes have been committed since commit A. Should I use a triple dot when running git log or a double dot?

Answer 1

the logging with two dots like

git log start-branch..end-branch

You will see a log of a series of commits. The commits will be all the commits reachable from end-branch that are not reachable from start-branch, So logging without dots is the same as Logging with two dots.

logging with three dots like

git log start-branch...end-branch

This three dot version of the command finds all commits that are reachable from start-branch, OR that are reachable from end-branch BUT that are NOT reachable from both start-branch AND end-branch. you will see all commits reachable from start-branch AND all commits reachable from end-branch BUT excluding any commits reachable from any common ancestor.

By example, from the history above, let’s think about what would we get from:

 git log topicB...topicA

From topicA we can reach this set of commits — G, F, E, D, C, B, A. From topicB we can reach J, I, H, D, C, B, A. That means that we can reach D, C, B, A from both of topicA AND topicB. So the returned commits would be G, F, E, J, I, H.