Checking That an Install Should Proceed
There are two ways to specify the installation requirements for your package. The first works only on 10.3 or later but is easier, safer, and involves modifying the Info.plist file. The second works on all versions of OS 10 and involves writing scripts.
The Requirements Mechanism
The requirements mechanism works only on systems running 10.3 or later. PackageMaker provides an interface to edit the requirements in the “Configuration” tab of the user interface. PackageMaker will make the necessary modifications to the Info.plist and will also write installation and volume check scripts for you.
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You can also specify the requirements by hand via editing the Info.plist. For more information, see Specifying Installation Requirements in the Software Distribution documentation.
This mechanism is safer as it does not involve executing arbitrary executables on the user's machine. Therefore, Installer.app will not present a warning before running these read-only checks.
InstallationCheck and VolumeCheck Scripts
In addition to scripts that scripts that run during the actual installation, you can also add scripts that check the user's machine to validate that an install can occur. The InstallationCheck
script validates that the install can be done on the user's machine while the VolumeCheck
validates that the install can be done on a specific volume. After 10.3, Installer.app asks the user before running these scripts.
For details on writing these scripts by hand, see the following pages in the Software Distribution documentation: