Option Directories -- Package Directories

The pkg and site subdirectories within the opt directory structure are very similar in layout. They both contain application directories, whose names are of the form appname-version. Examples are emacs-19.15 and xlockmore-4.04BETA.

The main difference between the contents of the pkg and site directories is that pkg contains packages which are freely available on the Internet; thus, the appname directory normally contains the source code for the application as well as the "installed" files (the binaries, libraries, etc.) for the app. The site directory contains locally maintained packages; their source code is usually elsewhere, in a configuration management system's repository.

Pathnames which contain the pkg or site directory names are used in only one place: in symbolic links in the opt directory itself. Those links are normally of the form

appname ---> pkg/appname-version

appname ---> site/appname-version

The appname directories within pkg and site contain the actual files of the application--the source (in the case of pkg directories), the binaries, the documentation, everything. Just about the only things that aren't in an application's appname directory are log files that the application creates, PID files, user data files created or used by the application, and sometimes configuration files. The intent is that all "static" files related to an application be contained in its appname directory.