Add Auto-Squash Those Fixup Commits as a git til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1016 TILs and counting..._
+_1017 TILs and counting..._
 
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@@ -213,6 +213,7 @@ _1016 TILs and counting..._
 
 - [Accessing a Lost Commit](git/accessing-a-lost-commit.md)
 - [Amend Author Of Previous Commit](git/amend-author-of-previous-commit.md)
+- [Auto-Squash Those Fixup Commits](git/auto-squash-those-fixup-commits.md)
 - [Caching Credentials](git/caching-credentials.md)
 - [Change The Start Point Of A Branch](git/change-the-start-point-of-a-branch.md)
 - [Checking Commit Ancestry](git/checking-commit-ancestry.md)

git/auto-squash-those-fixup-commits.md

@@ -0,0 +1,29 @@
+# Auto-Squash Those Fixup Commits
+
+As a fan of [atomic commits](https://dev.to/jbranchaud/atomic-commits-4hk2), I
+sometimes find myself with some changes that are ready to stage that belong on
+an earlier commit. If it is the immediately previous, I'll do an `--amend`. For
+anything further back than that, I've come to love the use of `git commit
+--fixup <SHA>`.
+
+Once one or more _fixup_ commits are on the current branch, they'll need to be
+_squashed_ into the commits for which they've been targeted. This calls for a
+`git rebase`.
+
+Git knows how to squash fixup commits into the correct place, but you have to
+tell it to do so automatically. You can do that one of two ways.
+
+You can either include the `--autosquash` flag each time you rebase:
+
+```bash
+$ git rebase -i --autosquash
+```
+
+Or you can tell Git to always autosquash in your `~/.gitconfig`:
+
+```
+[rebase]
+	autoSquash = true
+```
+
+See the section on `--autosquash` in `man git-rebase` for more details.