[CentOS] upgrade question.

Robert Nichols rnicholsNOSPAM at comcast.net
Fri Jan 9 16:49:33 UTC 2009

Brian wrote:
>    I've did some googling and have not came up with and answer yet. Is 
> there
> a list of packages that after update require a reboot, other then kernel?

That is a difficult question, and the answer depends on how certain you
need to be that no running process is still using the old version.  For
system daemons, a restart is typically done in the post-install script,
provided that can be done non-disruptively.  Long-running user processes
(shells, browsers, mail readers, etc., etc.) will still be using the old
versions of executables, libraries, and other resources until the user
terminates the process or logs out.  Library updates in particular are
a big problem because there is no reliable way to know whether the (now
unlinked) old version is still in use.  For a lot of files, "lsof |
egrep 'DEL|deleted'" will show deleted versions still in use, but
libraries in particular are typically mmap()ed and closed, so lsof
won't pick them up even though they are still in use.

For updates other than the kernel, there is almost always an answer
short of a full reboot.  But, finding that answer and being 100%
certain that it is a complete answer can be a challenge, and is,
say, bringing the system down to single-user mode momentarily all
that much better than simply rebooting?

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

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