git config --global core.excludesfile ~/.gitignore
echo .DS_Store >> ~/.gitignore

Here's how to set-up globally a set of excludes when using GIT, in this case setting up GIT to ignore .DS_Store files on a Mac.

First add a common ignore file to the GIT configuration, in this case stored in the users home directory called .gitignore

Next add the exclude line for .DS_Store to the .gitignore file either with your favourite editor or simply with this command which will create it if it doesn't already exist as well.

Git ignore global

Bash