set environment path in .nsi file without system reboot - environment-variables

Question

We are using an eclipse rcp product which is having .nsi file.
So, I want to set the path in environment variables in .nsi file.
I wrote the below piece of code:
Section "-Environment"
ReadRegStr $1 HKCU "Environment" "PATH"
;DetailPrint $1
StrCpy $0 $INSTDIR\MKS_Standalone\mkssi
;DetailPrint $0
StrLen $2 $1
;DetailPrint $2
StrLen $3 $0
;DetailPrint $3
IntOp $5 $5 & $5
IntOp $6 $2 - $3
;DetailPrint $6
IntCmp $2 0 labelWrite
labelLoop:
;DetailPrint $5/$6
StrCpy $4 $1 $3 $5
;DetailPrint $4
;DetailPrint $0
StrCmp $4 $0 labelEnd
IntOp $5 $5 + 1
IntCmp $6 $5 labelAdd labelAdd
Goto labelLoop
labelAdd:
WriteRegExpandStr HKCU "Environment" "PATH" $1;$INSTDIR\MKS_Standalone\mkssi
DetailPrint "Adding path environment."
Goto labelEnd
labelWrite:
WriteRegExpandStr HKCU "Environment" "PATH" $INSTDIR\MKS_Standalone\mkssi
DetailPrint "Adding path environment."
labelEnd:
SectionEnd
This piece of code is adding the path in environment variables but only after rebooting the machine.
Since my application is running on several machines, I cannot reboot the machine for updating path variables.
How can I set PATH using nsis without system reboot?

Answer 1

Child processes inherit their parents environment. You can update the installers environment like this: System::Call 'Kernel32::SetEnvironmentVariable(t "name", t "value")'.
You can announce the change to other running applications like this:
!include WinMessages.nsh
SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000`
Explorer.exe is usually the only process that handles this message and reloads its environment.