git-cheat-sheet

How to do stuff with git

Splitting a repo

Remove history of all but select files in cloned repo

$ 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

$ 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

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

Deleting all tags, locally and remotely

for tag in `git tag`;
do
    git tag -d $tag
    git push $REMOTE_NAME :refs/tags/$tag
done

Get an older version of a file

git cat-file -p $COMMIT_DIGEST:$FILE_PATH

Splitting a commit

From docs:

• Start an interactive rebase with git rebase -i <commit>^, where <commit> is the commit you want to split.
• Mark the commit you want to split with the action “edit”.
• When it comes to editing that commit, execute git reset HEAD^. The effect is that the HEAD is rewound by one, and the index follows suit. However, the working tree stays the same.
• Now add the changes to the index that you want to have in the first commit (git add)
• Commit the now-current index with whatever commit message is appropriate now.
• Repeat the last two steps until your working tree is clean.
• Continue the rebase with git rebase --continue.