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InstallShield 11.5 provides an easy way to search the registry for a desired value

Oftentimes when creating a new installer, it is necessary to provide for the contingency of previously installed software that will need to be removed. This can be a previous version of the same software (although those modules should maintain the same unique IDs, making this extra procedure unnecessary) or it can be a piece of software that will conflict with the software you’re trying to install (i.e. an old anti-virus program). Either way, in order to effectively remove the software, you’re going to need to:

1) Search for the program’s existence, and
2) Run its UninstallString from the registry.

Thankfully, InstallShield provides a couple of easy ways to accomplish this. The first (ideal) way to run the other software’s uninstaller is to do a simple system search for the registry key UninstallString for the program you wish to remove. The advantage to this method is that the search is very specific–it only looks within a particular key–so you can easily do 100 of these searches in the course of an install. In order to create the appropriate Custom Action within your MSI in this manner, do the following:

1) In the ‘System Search’ screen, add a new search by right-clicking and choosing ‘Add…’ (or hit Ins).
2) Choose ‘File Path, as specified by a registry entry’ at the next screen.
3) For the Registry Root choose ‘HKEY_LOCAL_MACHINE’
4) For the Registry Path type ‘SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\**ProgramName**’ (in other words, to uninstall Macromedia Flash, type ‘SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Macromedia Shockwave Player’
5) Under the optional Registry Value field, type ‘UninstallString’
6) Pick a memorable name for your new file-path variable like FLASH8PATH, then choose the top option to only store it in the tables, not use it as an install condition (you will attach the custom action later).

Your System Search is now complete, and will look for the UninstallString for Flash Player, then store that value to the variable FLASH8PATH. If you wish, you can immediately use this variable to create Install Conditions for different Custom Actions, either as an exists/does not exist check that launches an .exe or something, or by using the actual path contained in the variable. To launch the uninstaller, create the following Custom Action:

Working Directory: SystemFolder
Filename & Command Line: FLASH8PATH
Return Processing: Synchronous (Ignores exit code)
In-Script Execution: Immediate Execution

NB: You need to schedule the Custom Action after the AppSearch action in the InstallExecute sequence, because that’s when the MSI checks the registry for the key…it will fail otherwise.

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