tar problem

[venabilis_(_at_)_uol_(_dot_)_com_(_dot_)_br]

Hi,

  I wrote a script to admin a bunch of openbsd machines where
one of the commands is "tar rf $tarfile $files", the problem is when
$tarfile doesn't exist tar gives me an error :
"tar: Failed open to read/write on backup.tar <no such file or 
directory>"

but its exit value is 0, shouldn't it be non-zero ?

Thanks for any help,

--venabilis