This is the procedure for updating (patching) the FreeBSD system by downloading (fetching) and installing the binary patches from a FreeBSD mirror.
What does patching mean?
If you have subscribed to FreeBSD errata notices or FreeBSD security advisories, which both are free announcement mail lists, then you will be notified of changes, that has been made to the FreeBSD system. You will be given valuable background information, related to each problem and security issue, but also its level of impact, workaround and solution. The solutions are called patches, because they fix (patch) problems and security issues. In order to keep your own FreeBSD system stable and secure, you should install these patches on your FreeBSD systems.
Determining version and patch level of FreeBSD.
Confirm, that you are running the current version and patch level of FreeBSD. The built-in freebsd-version utility can determine the installed, running and userland version and patch level of FreeBSD. These should all match, but it is not uncommon, that userland is different.
# freebsd-version -k -r -u
Download (fetch) and install patches for the FreeBSD system.
Fetch and install the binary patches from a FreeBSD mirror with the built-in FreeBSD update tool. When the tool lists, which files, that will be added and changed as part of the updating to the new patch level, you can press Space to list more files and Q to quit listing and continue the updating proces until you are back at the command prompt.
# freebsd-update fetch install
If not already set, I recommend, that the pager is set to cat.
# PAGER=cat freebsd-update fetch install
Rebooting FreeBSD.
If this update was performed on a server or other critical production system, then a reboot and test of services is recommended.
In the following example, your command history will be saved and users will have some time to exit properly.
# shutdown -r +30s
# exit
In the following example, the system rebooted right away. Your command history will be lost.
# reboot
Determine new patch level.
Confirm, that the system was patched by determining the new installed, running and userland version and patch level of FreeBSD.
# freebsd-version -k -r -u
More about updating FreeBSD.
⧐ How to upgrade to new minor and major releases of FreeBSD.
⧐ How to upgrade and audit packages in FreeBSD.