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visual-studioinstallationregistryenvironment-variables

Using windows environment variables as registry values in Visual Studio Installer

Hey, i want to use windows environment variables as value for a registry entry. Unfortunately i can not simply write sth like %systemroot%\system32\MyScreensaver.scr.

As you can guess, i want to point some reg values to my own app, such as the auto start and screensaver and some other things.

Any ideas?

Solution

  • The Windows registry supports this natively with the REG_EXPAND_SZ registry value type.

    Just use REG_EXPAND_SZ instead of REG_SZ when you want to embed environment variables in the registry key value.

    Here is an example of C# code accessing a REG_EXPAND_SZ and the expansion is handled automatically:

    var registry = Registry.CurrentUser.OpenSubKey("Environment");
var temp = registry.GetValue("TEMP") as string;

    Here is an example of creating an expandable registry value:

    registry.SetValue("TEMP", @"%USERPROFILE%\AppData\Local\Temp", RegistryValueKind.ExpandString);

    Other platforms or scripting languages have other mechanisms to support this. Here is the low-level Win32 description of REG_EXPAND_SZ: