Proper way to run the setup in silent mode is, and always be executing it with /SILENT command line parameter. For instance this way:
setup.exe /SILENT
After we clarified your requirement in comments I see, that you actually want to build a setup, which will run in silent mode without the mentioned command line parameter. Currently, there’s no built-in way to tell the compiler, that you want to build a silent setup, so we need to workaround this by re-running the setup with the /SILENT command line parameter when the setup is being initialized.
The following script shows this workaround:
[Setup]
AppName=My Program
AppVersion=1.5
DefaultDirName={pf}\My Program
[Code]
#ifdef UNICODE
#define AW "W"
#else
#define AW "A"
#endif
type
HINSTANCE = THandle;
function ShellExecute(hwnd: HWND; lpOperation: string; lpFile: string;
lpParameters: string; lpDirectory: string; nShowCmd: Integer): HINSTANCE;
external 'ShellExecute{#AW}@shell32.dll stdcall';
function InitializeSetup: Boolean;
begin
// if this instance of the setup is not silent which is by running
// setup binary without /SILENT parameter, stop the initialization
Result := WizardSilent;
// if this instance is not silent, then...
if not Result then
begin
// re-run the setup with /SILENT parameter; because executing of
// the setup loader is not possible with ShellExec function, we
// need to use a WinAPI workaround
if ShellExecute(0, '', ExpandConstant('{srcexe}'), '/SILENT', '',
SW_SHOW) <= 32
then
// if re-running this setup to silent mode failed, let's allow
// this non-silent setup to be run
Result := True;
end;
end;