Post-Receive hook. Runs when the repository is pushed to.

post-receive

#!/bin/bash
while read oldrev newrev refname
do
  if [ "$refname" == "refs/heads/master" ]; then
    WORKDIR=/path/to/local/repo
    export GIT_DIR=$WORKDIR/.git
    pushd $WORKDIR >/dev/null
    git pull --quiet >/dev/null
    # run some code
    popd >/dev/null
  fi
done