how to change file permissions in postfix?

In开发者_C百科 the postfix main.cf I have configured service to invoke external php script.

smtp      inet  n       -       -       -       -       smtpd -o content_filter=myservice:www-data


myservice    unix  -       n       n       -       1      pipe
flags=Rq user=me null_sender=
argv=/home/me/my_script.php

so far so good, my_script.php is executed. It creates the file my_file.txt in home dir. However I can only manage

-rw------- 1 me   www-data     16 2009-10-11 19:35 my_file.txt

How do I add 'r' permissions for www-data group ?

You can explicitly set that in your script.

You also haven't specified the group your script is running as (the group= parameter).

Why do you need to grant group permissions in the first place? That to me is generally (not always) a flag indicating lack of proper design.