UAC plug-in

From NSIS Wiki

Author: Anders (talk, contrib)

Plugin Info

  • Version: 0.2.4c (20150526)
  • Type: Runtime plugin
  • Character encoding: Ansi
  • Minimum OS: Win95/NT4 (Elevation on Win2000+)
  • Minimum NSIS Version: 2.45
  • License: zlib
  • Download: (50 KB)


This plug-in attempts to work around UAC installation problems on Win2000+. This plug-in allows your installer to operate with a user level process and an admin level process. This allows you to accomplish things that would otherwise be very difficult. For example, you can have an elevated installer instance launch another process as the user.

It all started in this thread. It has been field tested with good results. It is still definitely in the beta stage (i.e. use at your own risk).

Basic Example

Basic script for a all users/shared installer.
It runs the installed application as the correct user...
!define S_NAME "UAC_Basic example"
Name "${S_NAME}"
OutFile "${S_NAME}.exe"
RequestExecutionLevel user ; << Required, you cannot use admin!
InstallDir "$ProgramFiles\${S_NAME}"
!include MUI2.nsh
!include UAC.nsh
!macro Init thing
!insertmacro UAC_RunElevated
${Switch} $0
${Case} 0
	${IfThen} $1 = 1 ${|} Quit ${|} ;we are the outer process, the inner process has done its work, we are done
	${IfThen} $3 <> 0 ${|} ${Break} ${|} ;we are admin, let the show go on
	${If} $1 = 3 ;RunAs completed successfully, but with a non-admin user
		MessageBox mb_YesNo|mb_IconExclamation|mb_TopMost|mb_SetForeground "This ${thing} requires admin privileges, try again" /SD IDNO IDYES uac_tryagain IDNO 0
	;fall-through and die
${Case} 1223
	MessageBox mb_IconStop|mb_TopMost|mb_SetForeground "This ${thing} requires admin privileges, aborting!"
${Case} 1062
	MessageBox mb_IconStop|mb_TopMost|mb_SetForeground "Logon service not running, aborting!"
	MessageBox mb_IconStop|mb_TopMost|mb_SetForeground "Unable to elevate, error $0"
SetShellVarContext all
Function .onInit
!insertmacro Init "installer"
Function un.onInit
!insertmacro Init "uninstaller"
!insertmacro MUI_PAGE_WELCOME
!insertmacro MUI_PAGE_FINISH
!insertmacro MUI_LANGUAGE "English"
Function PageFinishRun
; You would run "$InstDir\MyApp.exe" here but this example has no application to execute...
!insertmacro UAC_AsUser_ExecShell "" "$WinDir\notepad.exe" "" "" ""
SetOutPath $InstDir
# TODO: File "MyApp.exe"
WriteUninstaller "$InstDir\Uninstall.exe"
Section Uninstall
SetOutPath $Temp ; Make sure $InstDir is not the current directory so we can remove it
# TODO: Delete "$InstDir\MyApp.exe"
Delete "$InstDir\Uninstall.exe"
RMDir "$InstDir"

Important Notes

  1. If you need to use the UAC plugin for the uninstaller as well, you will need to initalize the UAC plugin for the uninstaller, such as through un.onInit.
  2. The outer/user process does not display any output as to what occurred. For example, if you have the outer/user process create a shortcut, and it fails, the inner/admin process currently visible will not display anything to indicate that a problem occurred. This is because the outer/user process does not yet communicate back to the inner/admin process.
  3. When a standard or limited user supplies administrator information into the Run As dialog, you may experience permissions trouble with any extracted file. For example, if a Windows 2000 standard user supplies administrator info into the Run As dialog, and the NSIS installer extracts an .exe file, then trying to call that .exe through an Exec can fail. If this is a problem, you will want to use the AccessControl plug-in.
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