pre-push that prevents a push to master

pre-push

# Color Definitions
RED=$(tput setaf 1)
GREEN=$(tput setaf 2)
BOLD=$(tput bold)
NORMAL=$(tput sgr0)

printf "${BOLD}Preventing restricted pushes...${NORMAL}\n\n"

protected_branch='master'

policy='${RED}[Error] Pushing to or deleting '$protected_branch' is prevented in this repo via git hooks${NORMAL}'

current_branch=$(git symbolic-ref HEAD | sed -e 's,.*/\(.*\),\1,')

push_command=$(ps -ocommand= -p $PPID)

is_destructive='force|delete|\-f'

will_remove_protected_branch=':'$protected_branch

is_pushing_to_master=$protected_branch

do_exit(){
  echo $policy
  exit 1
}

if [[ $push_command =~ $is_destructive ]] && [ $current_branch = $protected_branch ]; then
  do_exit
fi

if [[ $push_command =~ $is_destructive ]] && [[ $push_command =~ $protected_branch ]]; then
  do_exit
fi

if [[ $push_command =~ $will_remove_protected_branch ]]; then
  do_exit
fi

if [[ $push_command =~ $is_pushing_to_master ]]; then
  do_exit
fi  

unset do_exit

printf "${GREEN}Allowed, proceeding with push!${NORMAL}\n\n"