checking action of git-pull

Hello,
  I am working against a git repository which is updated at non regular
intervals; sometimes it takes a day and sometimes a week or two.

I have a script in crontab which runs daily which tries "git pull" of
this repository.

I want write a bash script which echoes yhe  result of this git pull
to a log file in such
a way that in case that any files were pulled, a short message
saying "files were pulled at date ddmmyyyy" will be added to a log file.
In case that there there were no changes, a message saying
"Already up-to-date (ddmmyyyy) will be added to a log file.

How can it be done ?
can I test somehow the return value of git pull in a bash script for
these two different
cases?

Regards,
Mark