How to display metadata about single commit in git?

Supply the quiet option to show to suppress the diff.

git show --quiet HEAD

So for your example, author name:

git show --quiet --pretty=format:%an

git --no-pager show -s --format='%an <%ae>' COMMIT

• --no-pager supresses the pager
• -s suppresses diff output; short for --no-patch
• %an is the author name
• %ae is the author email

(Taken from quora.com)