A pre-receive hook script to prevent someone to commit certain files

pre-receive-hook.sh

#!/bin/sh

# Check to see if this is the first commit in the repository or not
if git rev-parse --verify HEAD >/dev/null 2>&1
then
    # We compare our changes against the previous commit
    against=HEAD^
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# Redirect output to screen.
exec 1>&2

# Check to see if we have updated the given file
if [ $(git diff-tree -r --name-only $against | grep <FILE_TO_BE_EXCLUDED> ) ];
then
    # Output colors
    red='\033[0;31m';
    green='\033[0;32m';
    yellow='\033[0;33m';
    default='\033[0;m';
    echo "${red}"
    echo "                                         "
    echo "                   |ZZzzz                "
    echo "                   |                     "
    echo "                   |                     "
    echo "      |ZZzzz      /^\            |ZZzzz  "
    echo "      |          |~~~|           |       "
    echo "      |        |-     -|        / \      "
    echo "     /^\       |[]+    |       |^^^|     "
    echo "  |^^^^^^^|    |    +[]|       |   |     "
    echo "  |    +[]|/\/\/\/\^/\/\/\/\/|^^^^^^^|   "
    echo "  |+[]+   |~~~~~~~~~~~~~~~~~~|    +[]|   "
    echo "  |       |  []   /^\   []   |+[]+   |   "
    echo "  |   +[]+|  []  || ||  []   |   +[]+|   "
    echo "  |[]+    |      || ||       |[]+    |   "
    echo "  |_______|------------------|_______|   "
    echo "                                         "
    echo "                                         "
    echo "${red} You are not allowed to commit this file    "
    echo "                                         "
    echo "${default}"
fi;

# set the exit code to 0 or 1 based upon your needs
# 0 = good to push
# 1 = exit without pushing.
exit 0;