The sysupgrade utility has been added to OpenBSD-CURRENT for automatic updates.

In OpenBSD has added utility sysupgrade, designed for automatic system updates to a new release or snapshot of the CURRENT branch.

Sysupgrade downloads the necessary files for the update, verifies them using signify, copies bsd.rd (a special ramdisk that operates completely in memory, used for installing, updating, and recovering the system) to bsd.upgrade, and initiates a system reboot. The bootloader, upon detecting bsd.upgrade, will start its automatic loading (which can be canceled by the user) and automatically update the system to the previously loaded version.

Sysupgrade can already be used for automatic updates to the latest daily snapshots of CURRENT, and starting from the OpenBSD 6.6 release, it is expected to be used for upgrading from release to release. Before sysupgrade, similar actions had to be done manually or automated independently.

For applying security updates and bug fixes to stable OpenBSD releases, the syspatchutility is still recommended, applying binary patches with fixes to the base system.

Source: opennet.ru