From: Ben Finney on
Lao Ming <laomingliu(a)gmail.com> writes:

> Since I have all of my lab machines update their OS automatically from
> a cron job, I'm wondering if it's possible to do the same with public
> domain software?

I doubt much, if any at all, of the software you use is public domain.
Almost any zero-cost software is still subject to copyright, and will
have license terms attached to the acts of copying and redistribution
(and other acts).

> Is there some software which I can obtain to enable this?

Choose a free-software operating system that has systematic repositories
of software packaged and updated frequently, like Debian GNU/Linux
<URL:http://debian.org/>.

--
\ “If you are unable to leave your room, expose yourself in the |
`\ window.” —instructions in case of fire, hotel, Finland |
_o__) |
Ben Finney