I just want to only turn on PHP errors and disable all notices and warnings in PHP files.
It is probably not the best thing to do. You need to at least check out your PHP error log for things going wrong ;)
# PHP error handling for development servers
php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_flag log_errors on
php_flag ignore_repeated_errors off
php_flag ignore_repeated_source off
php_flag report_memleaks on
php_flag track_errors on
php_value docref_root 0
php_value docref_ext 0
php_value error_log /home/path/public_html/domain/PHP_errors.log
php_value error_reporting -1
php_value log_errors_max_len 0