When you use the pkg update command with no package FMRI or pattern specified, or with an asterisk character (*) as the pattern, all installed packages that have updates available are updated to the newest version allowed by the constraints imposed on the system by installed package dependencies and publisher configuration.
No new packages are installed unless they are new dependencies required by an updated installed package.
Installed packages are updated only if a configured publisher provides an updated version that fits the constraints of the image being updated. Constraints are imposed by package dependencies and by configuration such as the following that you can control as described in Chapter 5, Configuring Installed Images:
Packages locked at a particular version
Facets and variants set in the image
Package signing properties configured
Publisher search order and stickiness
If any required package cannot be installed, no packages are updated or installed. See Appendix A, Troubleshooting Package Installation and Update.
If non-global zones are installed in the current image, these zones are also updated. See Working with Non-Global Zones.