dovecot - Aug 2010 - Dovecot lda with qmail

Dear All,
              According to my setup i can not call
|/var/qmail/bin/preline -f /usr/local/libexec/dovecot/dovecot-lda
from my /var/qmail/control/defaultdelivery file, Instead making a perl
file which will call the same for delivery of mails.

If i put the following code in my mail.pl  |/var/qmail/bin/preline -f
/usr/local/libexec/dovecot/dovecot-lda then it throws error in running
file from command line.

Warning: Use of "-f" without parentheses is ambiguous at
/var/qmail/bin/mail.pl line 2.
syntax error at /var/qmail/bin/mail.pl line 2, near "|"
Execution of /var/qmail/bin/mail.pl aborted due to compilation errors.

content of mail.pl

#!/usr/bin/perl
|/var/qmail/bin/preline -f /usr/local/libexec/dovecot/dovecot-lda

Any help will be useful for me.

Thanks

On Thu, 2010-08-19 at 10:37 +0530, Piyush Joshi wrote:
>               According to my setup i can not call
> |/var/qmail/bin/preline -f /usr/local/libexec/dovecot/dovecot-lda
> from my /var/qmail/control/defaultdelivery file, Instead making a perl
> file which will call the same for delivery of mails.
Why? What is the perl script going to do that the direct call isn't?
> #!/usr/bin/perl
> |/var/qmail/bin/preline -f /usr/local/libexec/dovecot/dovecot-lda
That's not a valid perl script.