Newbie Question About System Update

[Bill Moran]

Matthias Buelow <mkb at incubus.de> wrote:

> Jim Campbell <jim-c at charter.net> writes:
> 
> >After that, I ran into problems.  It took me a little while to figure 
> >out how to do "boot -s".  However, it appears that a lot of the 
> >directories aren't mounted and the next scripts aren't in the path.  For 
> >example, I can't figure out how to do the "mergemaster -p".
> 
> You don't have to do it in single user mode, I never did.  I don't know
> why it is recommended that one boots in single user in the Makefile,
> perhaps to get a quiescent system without any users and services that
> would interfere.  But that can also be achieved by stopping the
> high-volume services on the machine after booting, and on a personal
> machine (workstation PC) it doesn't matter anyways.  Often it's not even
> possible to boot into single-user, for example if you don't have
> physical control over the machine (like in a co-lo situation).

This isn't really true.

Fact is, trying to update a running system could result in silent failures.
The system can not replace programs that are in use, so there's always the
chance that something or other won't get updated (cron would be an excellent
example ... do you always shut cron off when you update?  How about syslogd?)

That being said, I quite often do installworld on running systems because I
have no way to go to single-user mode.  It almost always works well enough
for my purposes, but I don't want anyone to think that it's "OK" to do this,
as it's not guaranteed to work, and will most likely result in some programs
not being updated (such as the examples in the previous paragraphs).

On a production system, you should have a serial terminal connected so you
can go to single-user mode remotely to do updates.  There are fairly
inexpensive serial terminal boxes available from a number of vendors, and
if you have a spare machine available, you can always hook it up as a
serial terminal.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com