Prevent git push --force for master branch (by @ErisDS from http://dev.ghost.org/prevent-master-push/)

pre-push

#!/bin/bash
# Prevents force-pushing to master.

protected_branch='master'  
current_branch=$(git symbolic-ref HEAD | sed -e 's,.*/\(.*\),\1,')
push_command=`ps -ocommand= -p $PPID`

if [[ $protected_branch = $current_branch && $push_command =~ force|delete|-f ]]
then  
  read -p "You're about to push master, is that what you intended? [y|n] " -n 1 -r < /dev/tty
  echo
  if echo $REPLY | grep -E '^[Yy]$' > /dev/null
  then
    exit 0 # push will execute
  fi
  exit 1 # push will not execute
else  
  exit 0 # push will execute
fi