Usepackage is a tool for managing the Unix environment for a multi-tool, multi-platform site. It is designed to simplify login scripts and allow administrators to control users' environments centrally. This tool should be considered primarily designed for sites where users have to deal with a number of different tools, or versions of tools, that are installed in different locations and require environment variables to be set. This is particularly a problem for developers, or anyone who has to manage a large toolset across multiple platforms (e.g. different versions of the Sun JDK which require various environment variables to be set correctly). One or more central configuration files control a number of different "packages" and their associated environment and dependencies for different platforms (this includes the standard PATH, MANPATH, and LD_LIBRARY_PATH variables). A single user command, use, can be invoked to source the appropriate environment information into the users' current shell.