X-Git-Url: https://git.xandkar.net/?p=git-cheat-sheet.git;a=blobdiff_plain;f=README.md;h=3dbce00338f4f05879d30dcba712e7f87206389e;hp=91c27665fffd9025ce85f5f9bc8aa0bc052bd875;hb=fe79085123faf9e524caa33bf00f0024b6589960;hpb=95f663c4c8150f23d128c2b8ef29056b318fb7b8

diff --git a/README.md b/README.md
index 91c2766..3dbce00 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,53 @@ git-cheat-sheet
 ===============
 
 How to do stuff with git
+
+
+Splitting a repo
+----------------
+
+##### Remove history of all but select files in cloned repo
+```sh
+$ git clone old new
+$ cd new
+$ git clean -dfx
+$ git gc --aggressive --prune=now
+$ git remote rm origin
+$ git filter-branch \
+    --prune-empty \
+    --index-filter '
+        git ls-tree -r --name-only HEAD \
+        | grep -v file_i_want_to_keep_1 \
+        | grep -v file_i_want_to_keep_.. \
+        | grep -v file_i_want_to_keep_n \
+        | xargs git rm --cached -r --ignore-unmatch
+    ' \
+    HEAD
+$ git gc --aggressive --prune=now
+```
+
+##### Remove history of previously-removed (not in current tree) files
+```sh
+$ git log --pretty=format: --name-status \
+    | awk '$0 != "" {print $2}' \
+    | sort -u > /tmp/tree.old
+$ git ls-tree -r --name-only HEAD > /tmp/tree.new
+$ git filter-branch \
+    --prune-empty \
+    --index-filter '
+        grep -Fvxf /tmp/tree.new /tmp/tree.old \
+        | xargs git rm --cached -r --ignore-unmatch
+    ' \
+    HEAD
+```
+
+
+Inserting a new root commit
+---------------------------
+```sh
+git checkout --orphan $TEMP_BRANCH
+git rm -rf .
+git commit --allow-empty -m $INIT_COMMIT_MSG
+git rebase --onto $TEMP_BRANCH --root $MAIN_BRANCH
+git branch -d $TEMP_BRANCH
+```