git hook that enforces that you've rebased origin/master before pushing

pre-push

#!/bin/sh

# Called by "git push" after it has checked the remote status, 
# but before anything has been pushed.  

# If this script exits with a non-zero status nothing will be pushed.
#
# This hook is called with the following parameters:
#
# $1 -- Name of the remote to which the push is being done
# $2 -- URL to which the push is being done
#
# If pushing without using a named remote those arguments will be equal.
#
# Information about the commits which are being pushed is supplied as lines to
# the standard input in the form:
#
#   <local ref> <local sha1> <remote ref> <remote sha1>
#
# This sample shows how to prevent push of commits where the log message starts
# with "WIP" (work in progress).

remote="$1"
branch="$(git rev-parse --abbrev-ref HEAD)"
printf -- "\n--- Checking rebase origin/master ---\n\n"
git fetch "$remote" "$branch"

# get last commit on origin/master
last_commit_master=$(git rev-parse origin/master)

# A user is rebased with origin/master if the last commit on origin/master is in the git history
if git merge-base --is-ancestor "$last_commit_master" HEAD
then
	exit 0
else
	printf "\nRebase required. Please run: \`git rebase origin/master\`"
	exit 1
fi