A Git pre-commit hook for validating code follows PHP's Fig Coding Standard. The script requires PEAR's Code Sniffer library. Change the variables to fit your project code structure. Just drop this file in your .git/hooks/ directory. This script is a modified file created by Soenke Ruempler.

gistfile1.sh

#!/bin/bash
# PHP CodeSniffer pre-commit hook for git
#
# @author Soenke Ruempler <soenke@ruempler.eu>
# @author Sebastian Kaspari <s.kaspari@googlemail.com>
#
# see the README

PHPCS_BIN=/usr/local/bin/phpcs
PHPCS_CODING_STANDARD=PSR2
PHPCS_IGNORE=lib/Smarty/,media/wifi/,tests/support/,migrations/,data/*.sqlite3,htdocs/css/images/,htdocs/images/,htdocs/js/,htdocs/vendor/
PHPCS_EXTENSIONS=php
TMP_STAGING=".tmp_staging"

# parse config
CONFIG_FILE=$(dirname $0)/config
if [ -e $CONFIG_FILE ]; then
    . $CONFIG_FILE
fi

# simple check if code sniffer is set up correctly
if [ ! -x $PHPCS_BIN ]; then
    echo "PHP CodeSniffer bin not found or executable -> $PHPCS_BIN"
    exit 1
fi

# stolen from template file
if git rev-parse --verify HEAD
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# this is the magic: 
# retrieve all files in staging area that are added, modified or renamed
# but no deletions etc
FILES=$(git diff-index --name-only --cached --diff-filter=ACMR $against -- )

if [ "$FILES" == "" ]; then
    exit 0
fi

# create temporary copy of staging area
if [ -e $TMP_STAGING ]; then
    rm -rf $TMP_STAGING
fi
mkdir $TMP_STAGING

# match files against whitelist
FILES_TO_CHECK=""
for FILE in $FILES
do
    echo "$FILE" | egrep -q "$PHPCS_FILE_PATTERN"
    RETVAL=$?
    if [ "$RETVAL" -eq "0" ]
    then
        FILES_TO_CHECK="$FILES_TO_CHECK $FILE"
    fi
done

if [ "$FILES_TO_CHECK" == "" ]; then
    exit 0
fi

# execute the code sniffer
if [ "$PHPCS_IGNORE" != "" ]; then
    IGNORE="--ignore=$PHPCS_IGNORE"
else
    IGNORE=""
fi

if [ "$PHPCS_ENCODING" != "" ]; then
    ENCODING="--encoding=$PHPCS_ENCODING"
else
    ENCODING=""
fi

if [ "$PHPCS_EXTENSIONS" != "" ]; then
    EXTENSIONS="--extensions=$PHPCS_EXTENSIONS"
else
    EXTENSIONS=""
fi

# Copy contents of staged version of files to temporary staging area
# because we only want the staged version that will be commited and not
# the version in the working directory
STAGED_FILES=""
for FILE in $FILES_TO_CHECK
do
  ID=$(git diff-index --cached HEAD $FILE | cut -d " " -f4)

  # create staged version of file in temporary staging area with the same
  # path as the original file so that the phpcs ignore filters can be applied
  mkdir -p "$TMP_STAGING/$(dirname $FILE)"
  git cat-file blob $ID > "$TMP_STAGING/$FILE"
  STAGED_FILES="$STAGED_FILES $TMP_STAGING/$FILE"
done

OUTPUT=$($PHPCS_BIN -s --standard=$PHPCS_CODING_STANDARD $EXTENSIONS $ENCODING $IGNORE $STAGED_FILES)
RETVAL=$?

# delete temporary copy of staging area
rm -rf $TMP_STAGING

if [ $RETVAL -ne 0 ]; then
    echo "$OUTPUT" | less
fi

exit $RETVAL