<!---- git ignore local files : TL;DR;---->
echo YOURFILE_OR_DIRECTOY >> .git/info/exclude
<!---- Description ---->
If you don't want to create a .gitignore file to share with others,
you can create rules that are not committed with the repository.
You can use this technique for locally-generated files that you don't
expect other users to generate, such as files created by your editor.
Use your favorite text editor to open the file called
.git/info/exclude within the root of your Git repository.
Any rule you add here will not be checked in, and will only ignore
files for your local repository.