git clone git@github.com:user/my-project.git .
git clone repo-url full-path-to-folder
# example
git clone git@github.com:org/repo.git /full/path/to/folder
# will clone "repo" to "/full/path/to/folder"
cd /full/path/to/folder/
git status
git clone git@github.com:whatever folder-name
git clone git@github.com:whatever .
git clone [repo]
cd [name of sub-dir]
git filter-branch --prune-empty --subdirectory-filter [path to sub-dir] HEAD