例子：安装程序与卸载程序互相检查互斥

/************************
      CheckMutex.nsi
************************/
;NSIS 安装程序与卸载程序互相检查互斥的例子
;编写：zhfi
;邮箱：
;主页：http://hi.baidu.com/zhfi1022/

#定义自己的互斥名称：#
#注意安：装程序不能与卸载程序相同！#
!define MyMutex_Install     "MyMutex_Install"
!define MyMutex_UnInstall   "MyMutex_UnInstall"

;--------------------------------
;Include Modern UI

!include "MUI.nsh"
!include "LogicLib.nsh"

;--------------------------------
;General

  ;Name and file
  Name "Mutex Test"
  OutFile "Mutex.exe"

;--------------------------------
#添加安装页面：#
  !insertmacro MUI_PAGE_Welcome
  !insertmacro MUI_PAGE_InstFiles
  !insertmacro MUI_PAGE_Finish
#添加卸载页面：#
  !insertmacro MUI_UNPAGE_Welcome
  !insertmacro MUI_UNPAGE_InstFiles
  !insertmacro MUI_UNPAGE_Finish

;--------------------------------
;加入语言文件
 
  !insertmacro MUI_LANGUAGE "SimpChinese"

;--------------------------------
;安装程序部分

Function .onInit
InitPluginsDir
Call CreateMutex
FunctionEnd

Function CreateMutex
#检查安装互斥：#
ReCheck:
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_Install}") i .R1 ?e'
Pop $R0
  System::Call 'kernel32::CloseHandle(i R1) i.s'
#检查卸载互斥：#
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_UnInstall}") i .R3 ?e'
Pop $R2
  System::Call 'kernel32::CloseHandle(i R3) i.s'
#判断安装/卸载互斥的存在#
${If} $R0 != 0
  MessageBox MB_RetryCancel|MB_ICONEXCLAMATION "安装程序已经运行！" IdRetry ReCheck
Quit
${ElseIf} $R2 != 0
  MessageBox MB_RetryCancel|MB_ICONEXCLAMATION "卸载程序已经运行！" IdRetry ReCheck
Quit
${Else}
#创建安装互斥：#
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_Install}") i .R1 ?e'
Pop $R0
  StrCmp $R0 0 +2
Quit
${EndIf}
FunctionEnd

Section Install
  SetOutPath $EXEDIR
  WriteUninstaller "$EXEDIR\Uninstall.exe"
SectionEnd

;--------------------------------
;卸载程序部分

Function un.onInit
InitPluginsDir
Call un.CreateMutex
FunctionEnd

Function Un.CreateMutex
#检查安装互斥：#
ReCheck:
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_Install}") i .R1 ?e'
Pop $R0
  System::Call 'kernel32::CloseHandle(i R1) i.s'
#检查卸载互斥：#
CheckUnInstall:
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_UnInstall}") i .R3 ?e'
Pop $R2
  System::Call 'kernel32::CloseHandle(i R3) i.s'
#判断安装/卸载互斥的存在#
${If} $R0 != 0
  MessageBox MB_RetryCancel|MB_ICONEXCLAMATION "安装程序已经运行！" IdRetry ReCheck
Quit
${ElseIf} $R2 != 0
  MessageBox MB_RetryCancel|MB_ICONEXCLAMATION "卸载程序已经运行！" IdRetry ReCheck
Quit
${Else}
#创建卸载互斥：#
  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "${MyMutex_UnInstall}") i .R1 ?e'
Pop $R0
  StrCmp $R0 0 +2
Quit
${EndIf}
FunctionEnd

Section Uninstall
  SetOutPath $EXEDIR
  Delete "$EXEDIR\Uninstall.exe"
SectionEnd

#脚本结束！#