How to git commit nothing without an error?

Question

I'm trying to write a fabric script that does a git commit; however, if there is nothing to commit, git exits with a status of 1. The deploy script takes that as unsuccessful, and quits. I do want to detect actual failures-to-commit, so I can't just give fabric a blanket ignore for git commit failures. How can I allow empty-commit failures to be ignored so that deploy can continue, but still catch errors caused when a real commit fails?

def commit():     local("git add -p && git commit") 

Answer 1

Catch this condition beforehand by checking the exit code of git diff?

For example (in shell):

git add -A git diff-index --quiet HEAD || git commit -m 'bla' 

EDIT: Fixed git diff command according to Holger's comment.

Answer 2

From the git commit man page:

--allow-empty     Usually recording a commit that has the exact same tree as its     sole parent commit is a mistake, and the command prevents you     from making such a commit. This option bypassesthe safety, and     is primarily for use by foreign SCM interface scripts.