On 29 Jul 2003, David Magda wrote:

> To apply? I thought they could be applied in multi-user, but they
> wouldn't take effect until you reboot. Am I mistaken in this?

Strictly speaking, yes you are. Once a file is overwritten (by
a patch for example), the old contents are gone. If the old
contents stay in memory (i.e., are not paged out), life will be
OK, probably. But suppose something that's expecting the old
file pages in the new one? Boom.

Now, if the system is in mutliuser mode, but is otherwise
quiescent, then yeah, as a rule, you can get away with adding
patches - assuming a reboot is performed shortly thereafter.
But I wouldn't recommend it on a busy production system.

Patches for stuff that isn't currently being used can be
added in multiuser mode more safely. For example, if there
are no ssh sessions currently running on the machine, patching
ssh can be done safely by disabling it, adding the patch, and
then re-enabling it. No reboot required.

--
Rich Teer, SCNA, SCSA

President,
Rite Online Inc.

Voice: +1 (250) 979-1638
URL: http://www.rite-online.net