Inno setup command line group parameter clarification

Question

I'm having trouble correctly using the /GROUP="" command line parameter for my installation when called by a parent installation. What exactly should be specified and what is the "base"?

For example, the parent installer determines the full path to where the start menu entries will be. If this path is passed to /GROUP, it gives an error about invalid characters; namely, :.

I know the parameter supports use of expand prefix, but does this mean the parent installer must determine which constant to "expand" rather than simply passing the already determined path?

UPDATE:
It seems I was mistaken in thinking I could select the "base" of the menu entries (all users, local). It seems this is done automatically, but perhaps this is a more complete example:
An older Wise installation determines the filesystem path where the menu entries will be installed. It then executes my installation and passes that path using /GROUP. This is where my problem arises because /GROUP expects only a directory, not a full path.

Answer 1

The /GROUP="x" parameter specifies the value for the {groupname} constant, eg. it should be of the form /GROUP="MyApp". It should not contain a path, or at least if it does contain one it should be a very shallow relative path such as /GROUP="MyCompany\MyApp".

If you are passing the parameter from a parent Inno install script and you want the child install to install icons into the same group as the parent then you should use /GROUP="{groupname}".

In all cases, the "root" of the path will automatically be chosen by Inno to be either {commonprograms} or {userprograms} depending on the PrivilegesRequired setting of the install script being run.

Note that if you are running the installer as part of an automatic update to an already-installed application, you should not pass the parameter at all. Inno will remember the user's previous selection and use this by default; in fact it's strongly recommended to not offer the user a chance to change this during interactive upgrades by setting the following:

[Setup]
DisableDirPage=auto
DisableProgramGroupPage=auto