Q:

git-commit -- show more lines of context

When doing a git commit git will open up $GIT_EDITOR for you to enter a commit message, with the diffs shown below. 
Is there a way of configuring git so that it shows more context in the diffs?  I'm thinking of something similar to grep's -C option, for showing more context in search results. 
Reading git-commit's manpage didn't enlighten me. 

A:

Reading showing more context in git add provided the solution.  Run the following command to provide 5 lines of context:
git config --global diff.context 5

