Find if a previous soft is installed
 

Hi, i am a newbie on NSIS and also on this forum. The script that i wrote installs a soft in a directory that i choose. Is there a way to find out if the soft is already installed on the computer, before i get to the component page and how to calculate the space required for installation.

Hope i will hear from you soon,
Thanks

How about InstallDirRegKey? See NSIS manual,

http://nsis.sourceforge.net/Docs/Chapter4.html#4.8.1.22

Required space calculated automatically by the installer on components page and on directory page.

thanks i will try

i have done this:

!define company "Home"
!define prodname "TestApp"
!define regkey "Software\${company}\${prodname}"

Section
InstallDirRegKey HKLM "${regkey}"
SectionEnd

Error: command InstallDirRegKey not valid in Section

then use InstallDirRegKey outside a section!

As described in manual this is an installer attribute, so you need to add it like this e.g.

Name "my app"
OutFile "myapp.exe"
InstallDirRegKey HKLM "Software\NSIS" ""

ok i have done this:
Name "my app"
OutFile "myapp.exe"
InstallDirRegKey HKLM "${regkey}" ""

i tested the installer but what i should do so when i try to use the installer will warn me that i have the soft already installed

Provided that ${regkey} is defined properly, installer finds automatically any previous installation.
If you want to pop up a warning or set up another action regarding to that previous installation then,
Function .onInit
ClearErrors
ReadRegStr $0 HKLM "${regkey}" ""
IfErrors done
MessageBox MB_OK "Previous installation detected here $0"
# code here
done:
ClearErrors
# other code here
FunctionEnd

i have attached the source...please take a look...i did what you told me to do but has no effect

thanks

Hopefully this minimal out of script will help you,

code:
!define uninstaller "uninstall.exe"

!define prodname "testapl"

!define company "Home"

!define regkey "Software\${company}\${prodname}"



Outfile 'test.exe'

InstallDir '$PROGRAMFILES\${prodname}'

InstallDirRegKey HKLM "${regkey}" ""

AutoCloseWindow false

ShowInstDetails show



!include "mui.nsh"



!insertmacro MUI_PAGE_DIRECTORY

!insertmacro MUI_PAGE_INSTFILES



!insertmacro MUI_LANGUAGE "English"



Function .onInit   

   ClearErrors

   ReadRegStr $0 HKLM "${regkey}" ""

   IfErrors done

   MessageBox MB_OK "Previous installation detected here $0" IDOK



   done:

   ClearErrors

FunctionEnd



Section

	SetOutPath "$INSTDIR"

	WriteUninstaller "${uninstaller}"

	WriteRegStr HKLM "${regkey}" "" "$INSTDIR"

SectionEnd



Section "Uninstall"

  Delete "$INSTDIR\${uninstaller}"

  RMDIR "$INSTDIR"  

  DeleteRegKey HKLM "${regkey}"

SectionEnd

It works...thanks a lot