In the evaluation phase, IPS compares the packages currently installed on the system with the end state, and compares package manifests of old and new packages to determine three lists:
Actions that are being removed.
Actions that are being added.
Actions that are being updated.
The action lists are then updated in the following ways:
Directory and link actions are reference counted, and mediated link processing is done.
Hard links are marked for repair if their target file is updated. This is done because updating a target of a hard link in a manner that is safe for currently executing processes breaks the hard links.
Editable files moving between packages are correctly handled so that any user edits are not lost.
Action lists are sorted so that removals, additions, and updates occur in the correct order.
All currently installed packages are then cross-checked to make sure that no packages conflict. Example conflicts include two packages that deliver a file to the same location, or two packages that deliver the same directory with different directory attributes.
If conflicts exist, the conflicts are reported and pkg exits with an error message.
Finally, the action lists are scanned to determine whether any SMF services need to be restarted if this operation is performed, whether this change can be applied to a running system, whether the boot archive needs to be rebuilt, and whether the amount of space required is available.