Git

• Merge multiple commits
• Rewrite author history
• Only keep a sub-directory

Merge multiple commits

Merge multiple previous commits together in a single commit.

git rebase -i HEAD~[NUMBER OF COMMITS TO MERGE]

Then, replace pick by squash on lines you want to discard the log message. Finally, remove the commit messages you want to discard to avoid being left with a multiline commit.

Rewrite author history

Change the author name and email address of all your commits in the history.

git filter-branch --commit-filter '
        if [ "$GIT_AUTHOR_EMAIL" = "original@email.address" ];
        then
                GIT_AUTHOR_NAME="New Name";
                GIT_AUTHOR_EMAIL="new@email.address";
                git commit-tree "$@";
        else
                git commit-tree "$@";
        fi' HEAD

git push --force --tags origin HEAD:master

Only keep a sub-directory

If you only need a specific sub-directory from a git repository, use the following command to prune everything else:

cd <git repository>
git filter-branch --prune-empty --subdirectory-filter <path to sub-dir> HEAD