release: add installation page

Sponsored by:	Rubicon Communications, LLC ("Netgate")

website/content/en/releases/12.4R/installation.adoc

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+---
+title: "FreeBSD 12.4-RELEASE Installation Instructions"
+sidenav: download
+---
+
+:releaseCurrent: 12.4-RELEASE
+:localRel: 12.4
+
+= FreeBSD {localRel}-RELEASE Installation Instructions
+
+== Abstract
+
+This article gives some brief instructions on installing FreeBSD {releaseCurrent} and upgrading the systems running earlier releases.
+
+== Table of Contents
+
+* <<install,Installing FreeBSD>>
+* <<upgrade,Upgrading FreeBSD>>
+
+[[install]]
+== Installing FreeBSD
+
+The Installing FreeBSD chapter of the FreeBSD Handbook provides more in-depth information about the installation program itself, including a guided walk-through with screenshots.
+
+[[upgrade]]
+== Upgrading FreeBSD
+
+If you are upgrading from a previous release of FreeBSD, please read upgrading section in the Release Notes for notable incompatibilities carefully.
+
+[[upgrade-source]]
+== Upgrading from Source
+
+The procedure for doing a source code based update is described in Updating FreeBSD from Source.
+
+For SVN use the releng/{localRel} branch which will be where any upcoming Security Advisories or Errata Notices will be applied.
+
+[[upgrade-binary]]
+== Upgrading Using "FreeBSD Update"
+
+The {{< manpage "freebsd-update" "8">}} utility supports binary upgrades of i386 and amd64 systems running earlier FreeBSD releases. Systems running 12.3-RELEASE can upgrade as follows:
+
+[.screen]
+----
+# freebsd-update fetch
+# freebsd-update install
+----
+
+Now the {{< manpage "freebsd-update" "8">}} utility can fetch bits belonging to {releaseCurrent}. During this process {{< manpage "freebsd-update" "8">}} will ask for help in merging configuration files.
+
+[.screen]
+----
+# freebsd-update upgrade -r 12.4-RELEASE
+# freebsd-update install
+----
+
+The system must now be rebooted with the newly installed kernel before the non-kernel components are updated.
+
+[.screen]
+----
+# shutdown -r now
+----
+
+After rebooting, {{< manpage "freebsd-update" "8">}} needs to be run again to install the new userland components:
+
+[.screen]
+----
+# freebsd-update install
+----
+
+At this point, users of systems being upgraded from earlier FreeBSD releases will be prompted by {{< manpage "freebsd-update" "8">}} to rebuild all third-party applications (e.g., ports installed from the ports tree) due to updates in system libraries.
+
+After updating installed third-party applications (and again, only if {{< manpage "freebsd-update" "8">}} printed a message indicating that this was necessary), run {{< manpage "freebsd-update" "8">}} again so that it can delete the old (no longer used) system libraries:
+
+[.screen]
+----
+# freebsd-update install
+----
+
+Finally, reboot into {releaseCurrent}
+
+[.screen]
+----
+# shutdown -r now
+----