Add Copy A File From Another Branch as a git til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1094 TILs and counting..._
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@@ -232,6 +232,7 @@ _1094 TILs and counting..._
 - [Clone A Repo Locally From .git](git/clone-a-repo-locally-from-git.md)
 - [Configure Global gitignore File](git/configure-global-gitignore-file.md)
 - [Configuring The Pager](git/configuring-the-pager.md)
+- [Copy A File From Another Branch](git/copy-a-file-from-another-branch.md)
 - [Create A New Branch With Git Switch](git/create-a-new-branch-with-git-switch.md)
 - [Delete All Untracked Files](git/delete-all-untracked-files.md)
 - [Determine The Hash Id For A Blob](git/determine-the-hash-id-for-a-blob.md)

git/copy-a-file-from-another-branch.md

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+# Copy A File From Another Branch
+
+After doing some work on a large feature branch, I wanted to split out some of
+the work into a separate smaller branch to create an initial PR. There were
+several files on the feature branch that I knew needed to be part of this
+smaller branch.
+
+To bootstrap this smaller branch, I need to check it out from main and then
+copy over the needed files.
+
+First, let's create a fresh branch:
+
+```bash
+$ git branch --show-current
+large-feature-branch
+
+$ git checkout main
+$ git checkout -b new-smaller-branch
+```
+
+Now I can start pulling over the files I care about:
+
+```bash
+$ git checkout large-feature-branch some/file/ICareAbout.js
+```
+
+This form of `git-checkout` looks on the specified branch for the specified
+file and copies that over to the index.
+
+Note: this will copy over any local, working tree changes that you've made to
+the named file.