Creating software upgrades

Developer's Topics
Chapter 12, Custom Distribution Mastering Toolkit

An ``upgrade'' is an installation that preserves configuration information from a previously installed version of the component and allows the component to use that configuration.

During an upgrade, custom(ADM) must determine the following information for each component:

Which components currently on the system (if any) to upgrade to the new version.
Which packages (if any) of the new component to install.

To determine which existing components to upgrade, custom reads the following attributes in the CDMT input files:

upgradeVersions: defines the component versions that the component can upgrade. Use this attribute when the new component is a new version of an older component with the same name. See ``Specifying the upgrade versions''.
upgradeMapping: defines the component or package names that the component can upgrade. Use this attribute if the component or package name or location changed between versions. See ``Specifying packages to upgrade''.

See cdmtInput(CDMT) for more information about these attributes.

If custom detects an upgradable version on the system being installed (the components specified by upgradeVersions and upgradeMapping exist on the system), it passes the SSO_UPGRADE_COMPONENTS environment variable to the ccs and cqs scripts. This variable defines the list of existing components to upgrade. If the SSO_UPGRADE_COMPONENTS list contains at least one item, the component will be installed in ``upgrade mode''.

In upgrade mode, custom passes either the UPGRADE or OLD_CUSTOM_UPGRADE keyword to the ccs and cqs scripts (depending on whether the component to upgrade was cut to the SSO standard using the CDMT or to the old perms-list standard using the Software Mastering Toolkit (SMT).

NOTE: When the cqs receives either the UPGRADE or OLD_CUSTOM_UPGRADE keywords, it should run non-interactively and save any old configuration information in the directory specified by the CCS_PERSISTENT_STORAGE variable. See ``Component script environment variables'' for more information.

To determine which packages of the new component to install, custom uses command-line options. See custom(ADM) for details.