How do you know when a reboot is required after yum update?

[steve]

Donald Russell wrote:
 > There have been times though when "things seemed odd" after a
 > particularly large number of updates were applied... rather than spend
 > untold amounts of time trying to solve them, I did a quick reboot...
 > perhaps that was overkill, but it definitely caused all processes to
 > restart.

Well, in general besides for a kernel update not much necessitates a reboot. In 
general, if 'things seem odd', you might want to consider one or more of the 
following things before a reboot:
a. Log out and log back in (if updates seem to contain a lot of desktop related 
stuff)
b. Log out, kill and restart the X/display manager (Ctrl+Alt+Backspace) (if 
there is an xorg package in the update)
c. Login through a virtual console (Ctrl+Atl+F[12345]) as root
     i. Go to init level 3 and return back to init level 5
    ii. Go to init level 1 and return back to init level 5
(if there are a whole bunch of updates which you don't want to check/guess about)

That was just a kind of thumb-rule -- the steps may/may not be necessary, but 
they are better than a reboot.

 > Perhaps if I knew more of the internal details of what's what, I'd have
 > known that all was needed was to restart daemon "x"...
 >
 > But, I'm not a member of that elite group (who know everything and are
 > much holier than "Windows mindset" people), so I do what works quickly
 > and leaves little unknown afterward.

Like Roberto, I do not intend to offend, but it is generally a good idea to:

a. Know what the services that are currently running on your system do. I don't 
mean you should read up all the man pages for all the daemons in depth, just 
learn why a service is/isn't required to run and then turn off the unnecessary ones.

b. Know what are the effect of the updates that you apply. Again, i don't mean 
read the changelog for all the updates being applied ...just check to see which 
area of the system they affect.

It takes just a little time but you'll learn a lot about your system that way. I 
know I do.

hth,
cheers,
- steve