I tried two ways to combine multiple commits in Git

When I put together a commit with rebase, I caused a petite or mischievous matter. I was advised that "patch should be used to reflect multiple commits at once", but when I googled, many methods of combining with rebase were introduced. I did not understand the difference between these two methods, so I will record it with my own caution.

Overview of the two methods in the first place

1. How to apply patch file

How to combine multiple commits into a single diff

• $ git diff -p <source branch> <derived branch >> a.patch Outputs the difference between the two branches as a patch file.
• Patch file name is arbitrary
• $ patch --dry-run -p1 < a.patch
  Check the difference file with a dry run (test run).
• $ patch -p1 < a.patch
  If you actually pour it after checking the difference, it will be in the state before git add.
• (+ Α) $ git diff <source branch> <derived branch> | patch -p1 In this way, you can also execute them all at once on one line.

2. How to put together with rebase

• $ git rebase -i HEAD ~ (number of commits going back from HEAD) Since vim starts up, edit and save the commit message and the sequence of commits.
• $ git push -f origin <branch>
  ** Be careful with forced pushes! !! ** **
• • The commit history before rebase has already been pushed, and if there is a conflict during rebase, follow the steps below.
• $ git co --ours(--theirs)
  If you can't apply only the changes in one branch at once, you have to edit it steadily ...?
• $ git add .
• $ git rebase --continue (continue rebase after conflict resolution) → When finished, again $ git push -f origin <branch>

Reference site

• Combine multiple commits into one with the [Git] rebase command
• Use git rebase -i to collect commits and clean the history!
• Be careful of conflicts when git pushing the summarized history.
• Modify the history of git commits (git rebase) 1/2
• Sort commits with git rebase

A little messy story with rebase

What failed

(@Personal branch) $ git merge develop
$ git rebase -i HEAD~Summarize commits with xx
$ git push -f origin <branch>

I took the above steps. What will happen? ... It was bad to use $ git rebase -i HEAD ~ xx if there was a commit by someone other than yourself between the commits you were trying to put together, as in this case. Putting it together with $ git rebase -i HEAD ~ xx, it also recommits other people's commits. At this time, it will be summarized as your own commit, so you will have committed yourself. I had to put together only my own commits first and then merge the develop branch. (See here)

Summary

General

• ** $ git push -f origin <branch> be careful! !! ** **
• When you rebase a branch with your commits distributed & someone else's commits, Recommit someone else's commit as your own commit.
• How to apply patch file → Since it does not modify the commit log of the personal branch, Can only be used to apply personal branch updates to the develop branch in bulk = Image of "extracting differences that are unique to individual branches as one difference and attaching them to the first commit of the develop branch"
• At this time, the commit log of the personal branch remains distributed.

approach

• (If you fall into this case) It is not good to merge as it is. → If you do, you can deal with it by recreating another branch & extracting your changes from the commit.
• The image of switching the root of a branch with $ git rebase.
• If your changes are scattered like this time: It seems that it is quick to re-cut in another branch and cherry-pick only for yourself. → Can be used as a wipe when you make a mistake in git operation ...
• If you can also use $ git reset, it will be easier to correct if you make a mistake. → It is even better if you can be aware of the options --soft, --hard, --mixed.
• Checkout to the branch to merge with → Merge a personal branch that has tampered with someone else's commit → You can also extract only the changes with $ git reset HEAD ^ without pushing (There is a possibility of a lot of conflicts ...)