(feat) Updated the git command blog.

content/post/Useful_Git_Commands.md

@@ -93,4 +93,14 @@ It is OK to repeatedly merge other branches to one branch. For example, we can r
 
 `git clone --filter=blob:none`: Download the git commit tree and the latest blob, but skipped the history blob at the time. Git will fetch for blob if you ask for history commit data. 
 
-If you are working with super large monorepo, you can use `scalar` command, an alternative `git` command that wraps up some `git` commands optimized for large repos. 
+If you are working with super large monorepo, you can use `scalar` command, an alternative `git` command that wraps up some `git` commands optimized for large repos. 
+
+If you have a series of commits, and you want to patch something up in the early commit, you can use: 
+
+```bash
+git commit -a --fixup=<old_commit_hash>
+# here, it will create a new patch commit on top of the head. 
+git rebase --autosquash main
+# apply the patch commit to the old commit, and then rebase the commit series. 
+# it runs rebase in the background, if it encounters something that cannot fix, that it will prompt you for rebasing. 
+```