记一个PHP交互模式下的warning

PHP调试的时候出现了警告: 

[root@localhost ~]# php -a

Interactive shell

php > $endDate = date('Y-m-d', strtotime("-1 days"));

Warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in php shell code on line 1

Warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in php shell code on line 1

Warning: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in php shell code on line 1

Warning: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in php shell code on line 1

php >

php >

php > date_default_timezone_set('Asia/Shanghai');

php >

php > $endDate = date('Y-m-d', strtotime("-1 days"));

        This warning is repeated every time there is an instance of code containing the strtotime() PHP function.

        To solve it, you must specify a default timezone into the /sites/default/settings.php file. Just add the following line into it:

                    ini_set('date.timezone',date_default_timezone_get());