NSIS unattended options

I want to build a NSIS-script, which has three section

• section Main
• section Minor
• section Shared

Shared is invisible and would be installed, if Main or Minor is checked. If I start the installer, every section (Main, Minor) is checked.

Now it should be able to define the section (in silent install). What have I to change, to only install Main or Minor or Both?

Name "Test"
Outfile "Test.exe"
;RequestExecutionLevel ?

!include "Sections.nsh"
!include "LogicLib.nsh"
!include "FileFunc.nsh" ;For GetOptions

Page Components "" "" EnforceSectionDependencies
Page InstFiles

Section /o "Main" SID_MAIN
DetailPrint Main
SectionEnd

Section /o "Minor" SID_MINOR
DetailPrint Minor
SectionEnd

Section "" SID_SHARED
DetailPrint Shared
SectionEnd

!macro CheckSectionSwitch sw sid
${GetOptions} $0 '${sw}' $9
${IfNot} ${Errors}
    StrCpy $1 1
    !insertmacro SelectSection ${sid}
${EndIf}
!macroend

Function .onInit
${GetParameters} $0
StrCpy $1 0 ;Any section swithes?
ClearErrors
!insertmacro CheckSectionSwitch '/Main' ${SID_MAIN}
!insertmacro CheckSectionSwitch '/Minor' ${SID_MINOR}

${If} $1 = 0
    ;Set defaults
    !insertmacro SelectSection ${SID_MAIN}
    !insertmacro SelectSection ${SID_MINOR}
${EndIf}

call EnforceSectionDependencies
FunctionEnd

Function EnforceSectionDependencies
!insertmacro UnselectSection ${SID_SHARED}
${If} ${SectionIsSelected} ${SID_MAIN}
${OrIf} ${SectionIsSelected} ${SID_MINOR}
    !insertmacro SelectSection ${SID_SHARED}
${EndIf}
FunctionEnd