String Manipulation

From regestry I get installdir:
c:\program files\software\driver

I need to change it to:
c:\program files\software\tools
and install my files here

What is better way to do it?

use the instruction

WriteRegStr HKLM SOFTWARE\MyApp "${MUI_PRODUCT}" $INSTDIR

But, in what part... begin..middle...or....end...
of the installation?

Using StrCpy is the easiest and the better way to do this (copy if you want):

StrCpy "$INSTDIR" "$INSTDIR" -7
StrCpy "$INSTDIR" "$INSTDIR\tools" 

And if you don't know the length of the last directory name use GetParent.