installing new kernels

[Chris Lewis]

In article <2534 at sud509.ed.ray.com> heiser at tdw206.ed.ray.com (Bill Heiser - Unix Sys Admin) writes:
|I've always been under the impression that a machine should be
|in single user mode before installing a new kernel.  As such,
|I've always brought the machine down before removing /unix and
|installing the new version there.

|If a machine is in a controlled lab environment where no one
|else will be logged in, is there any reason not to install a
|new /unix while in multi-user mode (with me being logged in 
|across the ethernet)?  The procedure would be something like this:

|- build new kernel
|- get rid of all logged in users
|- cd /
|- remove (or move) old /unix
|- cp in new unix
|- shutdown -r (or whatever to reboot)

|Is there a problem with this?  All the manuals, etc, always
|say to be in single user.  Is there a reason for that?

The only difficulty with doing it this way is that any program that
tries to read /unix and /dev/kmem (such as "ps") will get grossly
confused.  Multi-user doesn't really matter, nor does having users logged
in, but ps will start behaving a bit strangely...  The /etc/rc.? shutdown
scripts might go a bit nutty if they attempt to do ps's to find out
the pids of stuff they have to kill.  But few (if any) of the shutdown
scripts do that.
-- 
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