Replace all occurrences of '2013 Magento Inc.' with '2012 Magento Inc.' in all files with '.php, '.xml' and '.phtml' extensions under current directory tree
find . -name '*.php' -print0 -o -name '*.xml' -print0 -o -name '*.phtml' -print0 | xargs -0 sed -i '' 's/2013 Magento Inc./2012 Magento Inc./g'