Detecting if a program is already installed with NSIS

Question

I\'m using NSIS to create an installer for a program, what is the best way to detect if this program is already installed? Also, since I\'m running the installer from the au

Answer 1

After creating your uninstaller create a product name entry in registry

!define PRODUCT_UNINST_ROOT_KEY "HKLM"
!define PRODUCT_UNINST_KEY "Software\Microsoft\Windows\CurrentVersion\Uninstall\${COMPANY_NAME} ${PRODUCT_NAME}"
Section -Post
  SetShellVarContext current
  WriteUninstaller "${UNINST_PATH}\uninst.exe"
  WriteRegStr ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}" "DisplayName" "$(^Name)"

To see if the product is installed do

Function IsProductInstalled
  ClearErrors
  ReadRegStr $2 ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}" "DisplayName"  
  StrCmp $2 "" exit

In your uninstall you should be doing

Section Uninstall
    DeleteRegKey ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}"