How can I get NSIS to install and execute files from a temp directory?

Question

I'm using the following NSIS script:

Name "My app wrapper"
Outfile "MyAppSetup.exe"
InstallDir $TEMP\MyApp\Install
Function .onInit
SetSilent silent
FunctionEnd
Section ""
    SetOutPath $TEMP\MyApp\Install
    File installer.msi
    File setup.exe
    Exec setup.exe
SectionEnd

The intention is that the installer will wrap up those two files, installer.msi and setup.exe (which is a bootstrapper to install prereqs and then call installer.msi) into the MyApp Setup.exe file. When MyAppSetup.exe is run, it should extract installer.msi and setup.exe to the $Temp\MyApp\Install directory, and it should run setup.exe from that directory.

However, when I run MyAppSetup from the desktop, it executes a setup.exe file that it finds on the desktop, and I don't even see a MyApp\Install directory in C:\Temp.

What do I need to do to get this script to install the files to the right location and to execute the right file?

Answer 1

Section
InitPluginsDir
SetOutPath "$pluginsdir\MyApp\Install" ;It is better to put stuff in $pluginsdir, $temp is shared

File installer.msi
File setup.exe

ExecWait '"$pluginsdir\MyApp\Install\setup.exe"' ;You should always use full paths and proper quotes

SetOutPath $exedir ;Change current dir so $temp and $pluginsdir is not locked by our open handle
SectionEnd