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We've been developing a project in a subfolder of the repository of it's only consumer project for a while. And recently this project has been proven to have wider usage in other projects, so we decided to move it into a standalone repository of it's own. And I got this task.

The folder structure looks like this:

.
├── the_subproject
├── some_files_I_want_to_include
└── other_directories_or_files_in_the_project

I need to create a new repository including everything in the_subproject folder, and some files in the outer project (such as .gitignore, .editorconfig, etc.).

Git has a built-in subcommand filter-branch, but it seems it's not recommended and the documentation gives this project filter-repo instead.

filter-repo is not installed with Git by default, but the installation is easy anyway. It's main project is a single Python script, so all we need is to download this file, and put it into the Git execution path (git --exec-path).

On Windows 10, because my default Python 3 is named python instead of python3, I also need to edit git-filter-repo and change python3 to python in the first line.

After that, just run this command to see the help:

git filter-repo -h

For my task, I need to clone my project into a new folder, preferably with the new project name. If the repository is not newly cloned, this command will not run unless we add a --force parameter.

git clone my_project_remote new_project_name

Then cd to new_project_name, run this command:

git filter-repo --path some_file_I_want_to_include \
    --path  another_file_I_want_to_include \
    --subdirectory-filter the_subproject

After that, I got a new project including my subproject files, and a few other files I want to include, and all the Git history is preserved.

For the --path parameter, I can also include files or folders that do not exist in the current project tree. For example, my the_subproject was renamed from old_subproject_folder, I can use --path old_subproject_folder to include this rename history, although old_subproject_folder no longer exists in the current project tree.