Master.cf Transport type - piping to Perl. How can I specify path to Perl?

[James Brown]

I have Postfix Admin’s Vacation setup and would like to use the Perl at 
/usr/local/bin/perl rather than /usr/bin/perl.

I have:

vacation        unix    -       n       n       -       -       pipe
        flags=DRhu user=_vacation argv="/usr/local/bin/perl 
/var/spool/vacation/vacation.pl" -f ${sender} -- ${recipient}

But Iog shows:

2019-01-21 15:48:09.726114+1100  localhost pipe[8806]: 8A484E5F63E: 
to=<testvacationuser#bordo.com...@autoreply.bordo.com.au>, 
orig_to=<testvacationu...@bordo.com.au>, relay=vacation, delay=0.25, 
delays=0.21/0.02/0/0.03, dsn=4.3.0, status=deferred (temporary failure. Command 
output: pipe: fatal: pipe_command: execvp "/usr/local/bin/perl: No such file or 
directory )

Any suggestions on how to accomplish this?

Thanks,

James.