Applying The Changes - Red Hat ENTERPRISE LINUX 4 - SECURITY GUIDE Manual

Chapter 3. Security Updates
Replace <old-kernel-package> in the previous example with the name of the older kernel RPM.
Note
It is not a requirement that the old kernel be removed. The default boot loader, GRUB,
allows for multiple kernels to be installed, then chosen from a menu at boot time.
Important
Before installing any security errata, be sure to read any special instructions contained
in the errata report and execute them accordingly. Refer to
Changes"

3.1.5. Applying the Changes

After downloading and installing security errata via Red Hat Network or the Red Hat errata website,
it is important to halt usage of the older software and begin using the new software. How this is
done depends on the type of software that has been updated. The following list itemizes the general
categories of software and provides instructions for using the updated versions after a package
upgrade.
Note
In general, rebooting the system is the surest way to ensure that the latest version of
a software package is used; however, this option is not always available to the system
administrator.
Applications
User-space applications are any programs which can be initiated by a system user. Typically, such
applications are used only when a user, script, or automated task utility launches them and they
do not persist for long periods of time.
Once such a user-space application is updated, halt any instances of the application on the
system and launch the program again to use the updated version.
Kernel
The kernel is the core software component for the Red Hat Enterprise Linux operating system. It
manages access to memory, the processor, and peripherals as well as schedules all tasks.
Because of its central role, the kernel cannot be restarted without also stopping the computer.
Therefore, an updated version of the kernel cannot be used until the system is rebooted.
Shared Libraries
Shared libraries are units of code, such as glibc, which are used by a number of applications
and services. Applications utilizing a shared library typically load the shared code when the
application is initialized, so any applications using the updated library must be halted and
relaunched.
To determine which running applications link against a particular library, use the lsof command
as in the following example:
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for general instructions about applying the changes made by an errata update.
Section 3.1.5, "Applying the