crontabs中的标志是什么意思?

I have this line in my crontab:

0 0 * * * /usr/local/bin/php5 -d allow_url_fopen=on -f /path/to/file.php

I cannot find any comprehensive reference on the meaning of the "-d" and "-f" flags. What do they mean? And is there a page that explains these and other flags?

From PHP manual:

-d foo[=bar]     Define INI entry foo with value 'bar'
-f <file>        Parse and execute <file>.

So this means that file /path/to/file.php should be executed with allow_url_fopen option set on.

The flags relate to the php5 command.

-d defines a variable -f sets the file to execute

http://www.manpagez.com/man/1/php/