Because the pkgadd and pkgrm commands update information in a software products database, it is important when you remove a package to use the pkgrm command--even though you might be tempted to use the rm command instead. For example, you could use the rm command to remove a binary executable file, but that is not the same as using pkgrm to remove the software package that includes that binary executable. Using the rm command to remove a package's files will corrupt the software products database. (If you really only want to remove one file, you can use the removef command, which will update the software product database correctly. See removef(1M) for more information.)
If you intend to keep multiple versions of a package (for example, multiple versions of a document processing application), install new versions into a different directory than the already installed package. The directory where a package is installed is referred to as the base directory, and you can manipulate the base directory by setting the basedir keyword in a special file called an administration file. See "Avoiding User Interaction When Adding Packages" and admin(4) for more information on use of an administration file and setting the base directory.