Software Structure

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Today, system software is structured in a manner to assist the administrator in installing all the software necessary to create a working system. Software dependencies are known by the installer, so that installing a software product will in turn install all the software required by the selected software. The installers will perform hardware scans and select the software needed to support the attached hardware. However, these processes may lead to installing unwanted or unexpected software. Understanding the organization of the system software will help in selecting the software to load and what is required to secure it.

Linux

Red Hat Linux uses rpm , Red Hat Package Manager, to install software. The files which make up a software system are grouped into packages. The rpm command installs this software into the appropriate location and checks for dependencies. It checks those packages on which the new package depends and it also makes sure the addition of this package will not interfere with the dependencies of any package already installed. It performs a number of checks during this phase. These checks verify that the command is not attempting to install an already installed package or attempting to install an older package over a newer version. The rpm command performs tasks which are required before the software is installed and those tasks which are needed after the installation.

Packages are organized into groups based on their function, for example, C Development, Networked Workstation, or Web Server.

HP-UX

HP-UX systems use the swinstall command to install software. The files which make up a software system are grouped into filesets. These filesets are independent autonomous units. Dependencies can be defined between filesets so that any fileset which depends on another fileset cannot be installed until the correct version of that fileset is installed.

Filesets are grouped into products. These groupings are used to contain everything which is included in a single purchasable product. Products can be grouped into bundles. These are groups of products which are sold together, like a workstation bundle or an e-business bundle.

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