InstallShield 2012 Express Edition User Guide - Knowledge Base ...

Chapter 10: Customizing Installation Behavior
Using Custom Actions
Any custom actions that make changes to the target system during an installation should be undone with
a rollback execution custom action in the event of rollback. For example, if you have a custom action that
creates a file, you should create a second custom action that deletes the file, and schedule the second
action for rollback execution. (A rollback custom action should be scheduled before the custom action it
reverses.)
Commit Execution
Commit execution actions do not run until the InstallFinalize action completes successfully. This means
that they wait until the installation has completed transferring files, registering COM servers, and
creating shortcuts and registry entries. Then, any actions that are set to commit execution launch in the
order in which they appear in the sequence.
For example, if you have a custom action that creates a temporary file, you should create a second
custom action that deletes the file, and schedule it for commit execution.
Deferred, Rollback, or Commit Execution in System Context
Like deferred execution actions, deferred-execution-in-system-context actions do not launch until the
script that generated by the Windows Installer is run. However, actions of this type execute with no user
impersonation.
Similarly, rollback-execution-in-system-context and commit-execution-in-system-context actions
execute with no user impersonation.
Because of the elevation of privileges on Windows Vista and later systems, deferred custom actions must
be made in system context if they need to make system changes that require elevated privileges.
Deferred custom actions in user context may not have elevated privileges even if an administrator runs
the installation on a Windows Vista or later system, and thus should be avoided for custom actions
requiring higher-level privileges.
Note: Custom actions that run in the system context generally do not have access to network resources.
Changing When Custom Actions Are Launched
The items in the Custom Actions view are organized by chronological order, according to when they are
launched during installation, maintenance, or uninstallation. When you add a custom action to your
project, you specify when the custom action should be launched by adding the action to the appropriate
installation, maintenance, or uninstallation item.
Task To change when a custom action is launched, do one of the following:
• Drag the custom action from its current location to the new location.
• Right-click the custom action and click Move Up or Move Down.
• Click the custom action and then press CTRL+SHIFT+UP ARROW or CTRL+SHIFT+DOWN
ARROW.
The Custom Actions view is divided into the following main run-time categories:
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