Add section on history cleanup

1 files changed, 69 insertions, 0 deletions

diff --git a/cheatsheet.txt b/cheatsheet.txt
index 92bee2e..20894f7 100644
--- a/cheatsheet.txt
+++ b/cheatsheet.txt
@@ -67,6 +67,75 @@ Rebasing
   git rebase origin[/master]
   git push --tags origin
 
+History Cleanup
+
+  This is the overall process for cleaning up the history in a feature
+  branch before merging it into master. The goal is to end up with a
+  nice and clean history in master, without any divergences and merges
+  that usually the result of the git merge command.
+
+  Note: make sure you have rerere enabled for this process to work
+  smoothly (~/.gitconfig).
+
+  Note: if you are just learning this procedure, make a local backup
+  copy of your repository in case things go badly and you need to
+  start from scratch.
+
+  To achieve this we first merge any unmerged changes that may be on
+  master and then rebase the whole thing on master. The end result of
+  this step is a history that first has all the commits that are from
+  master followed by all the commit from the feature branch (in other
+  words, master is now a prefix of our history which means we can
+  fastforward-only (--ff-only) merge this history into it):
+
+  git cout feature
+  git merge master
+  git rebase master
+
+  At this stage, run gitk and verify that you now have a linear history
+  that starts with master.
+
+  The second step is to clean up the commit history of our feature
+  branch since it may have "dirty", work-in-progress commits. This may
+  involve squashing several commits into one, rewording commit messages,
+  and possibly reordering the commits. The swiss army knife for this
+  is the interactive git rebase:
+
+  git rebase -i HEAD~<N>
+
+  Where <N> is the number of commits you would like to cleanup. Generally,
+  if you want to work on all the commits on this feature branch run gitk
+  and count the number of commits from the top to the first commit that
+  is on master (and if you know a better way to achieve the same result,
+  let me know). That is your <N>.
+  
+  Note also that the order of commits in the resulting edit file will
+  be the reverse of what you see in gitk.
+
+  Once in the edit file, use commands to squash, reword, or reorder
+  the history (note that squashing several commits automatically
+  means rewording the commit message). Note also that you can re-run
+  this command multiple times. For example, you can squash some
+  commits, then examine the history (with gitk), then squash some
+  more, etc.
+
+  Finally, once the history is cleaned up, we can merge it into
+  master:
+
+  git cout master
+  git merge --ff-only feature
+
+  Verify with gitk everything looks good on master and push:
+
+  git push
+  
+  It is also a good idea to delete the feature branch, both locally
+  and on the origin:
+
+  git br -d feature
+  git push origin :feature
+
+
 Submodules
 
   git config --global status.submoduleSummary true