[support] Can't clear cache with drush (file permissions)

[Tim Johnson]

I'm getting file permission errors while trying to clear caches
using drush.

FYI:
This is on my own workstation.
OS = Mac OSX
drush version 5.8
Running as user tim with :
linus:~ tim$ id
...,70(_www),...

apache is user _www

files involved are user:group _www:_www
permissions are 664 on files, 755 on the directory, which is 
  sites/default/files/js

I note that sites/default/files/css is being handled without error
and has permissions of 775

I want to automate this process for the command line as much as
possible so would like a solution that doesn't entail clearing from
the site itself

Would there be anything wrong with changing directory permissions on 
  sites/default/files/js to 775?
(My workstation is closed to the outside world)

TIA
-- 
Tim 
tim at tee jay forty nine dot com or akwebsoft dot com
http://www.akwebsoft.com