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Chapter 4. General Updates

In-place upgrade from Red Hat Enterprise Linux 6 to Red Hat Enterprise Linux 7

An in-place upgrade offers a way of upgrading a system to a new major release of Red Hat Enterprise Linux by replacing the existing operating system. To perform an in-place upgrade, use the Preupgrade Assistant, a utility that checks the system for upgrade issues before running the actual upgrade, and that also provides additional scripts for the Red Hat Upgrade Tool. When you have solved all the problems reported by the Preupgrade Assistant, use the Red Hat Upgrade Tool to upgrade the system.
Note that the Preupgrade Assistant and the Red Hat Upgrade Tool are available in the Red Hat Enterprise Linux 6 Extras channel, see (BZ#1432080)

The setup package now provides a way to override unpredictable environment settings

The setup package now provides and sources the sh.local and csh.local files for overrides of environment variables from the /etc/profile.d directory, which is sourced last. Previously, an undefined order could result in unpredictable environment settings, especially when multiple scripts changed the same environment variable. (BZ#1344007)