git pre-push hook to check and print how many commits behind origin/master you are

gistfile1.txt

#!/bin/bash

git-log-flat-message-author () {
  git log --format="%s %an" "$@"
}
git-log-flat-colored() {
  git --no-pager log --format="%C(yellow)%h%Creset %C(cyan)%cd%Creset %s %Cgreen%an%Creset" --date=short "$@"
}

REFERENCE_BRANCH="origin/releases/master"
# check if "origin/releases/master" branch exists, if so, fetch from origin and check if we're behind it
git rev-parse --verify ${REFERENCE_BRANCH} > /dev/null 2>&1
if [ "$?" == "0" ]; then

    echo "[-] Fetching from origin..."
    #git fetch origin

    echo "[-] Checking if your branch is in sync with ${REFERENCE_BRANCH} (ignoring automated build commits)..."
    NB_COMMITS_BEHIND=$(git rev-list --left-right --count ${REFERENCE_BRANCH}...@ | cut -f1)
    # check how many of the commits we're behind are really important ones (not automated version bumps from build scripts)
    NB_IMPORTANT_COMMITS_BEHIND=$(git-log-flat-message-author ${REFERENCE_BRANCH} | head -"${NB_COMMITS_BEHIND}" | grep -v "BUILD_BOT" | wc -l)

    if [ "${NB_IMPORTANT_COMMITS_BEHIND}" -gt "0" ]; then
      echo -e "[-] Your branch is ${NB_COMMITS_BEHIND} commits behind ${REFERENCE_BRANCH}, think about rebasing\n"
      git-log-flat-colored ${REFERENCE_BRANCH} | head -"${NB_COMMITS_BEHIND}"
      echo -e "\n[-] To rebase, run 'git rebase ${REFERENCE_BRANCH}' or 'remaster'"
    else
      echo -e "[-] Good job, your branch is in sync with ${REFERENCE_BRANCH}"
    fi

fi