How to avoid merge-commit hell on GitHub/BitBucket
"Todd A. Jacobs" already mentioned "rebase" is the concept here. This is just a more detailed way of doing things.
Let's say you're on the master branch
$ git branch
* master
You want to make a fix, so create a “fixbranch” which is branched from the master
$ git checkout -b fixbranch
Maybe you would have worked for a couple of days on this branch and had a couple of commits.
The day you wanted to push your commits to central master repo! Checkout master and get the latest changes from the central master repo
$ git checkout master
$ git pull origin master
Rebase your fixbranch with the master to have a clean history and resolve the conflicts if any in the local repo itself.
$ git checkout fixbranch
$ git rebase master
Now fixbranch is uptodate to with the central master, let me merge fixbranch into the master branch
$ git checkout master
$ git merge fixbranch
I’m done! let me push local master to the central master
$ git push origin master
https://git-scm.com/book/en/v2/Git-Branching-Rebasing
Rebase Feature Branches Before Merging
If you want to avoid merge commits, you need to ensure all commits are fast-forwards. You do this by making sure your feature branch rebases cleanly onto your line of development before a merge like so:
git checkout master
git checkout -b feature/foo
# make some commits
git rebase master
git checkout master
git merge --ff-only feature/foo
Rebase also has a lot of flags, including interactive rebasing with the -i flag, but you may not need that if you're keeping things as simple as possible and want to preserve all of your branch history on a merge.
Use the --ff-only Flag
Aside from rebasing, the use of the --ff-only flag will ensure that only fast-forward commits are allowed. A commit will not be made if it would be a merge commit instead. The git-merge(1) manual page says:
--ff-only
Refuse to merge and exit with a non-zero status unless the current HEAD is already up-to-date or the merge can be resolved as a fast-forward.