http://www.autohotkey.com/board/topic/96903-simplified-versions-of-seans-stdouttovar/

StdOutToVar.ahk

StdOutToVar( sCmd ) { ;  GAHK32 ; Modified Version : SKAN 05-Jul-2013  http://goo.gl/j8XJXY                             
  Static StrGet := "StrGet"     ; Original Author  : Sean 20-Feb-2007  http://goo.gl/mxCdn  
   
  DllCall( "CreatePipe", UIntP,hPipeRead, UIntP,hPipeWrite, UInt,0, UInt,0 )
  DllCall( "SetHandleInformation", UInt,hPipeWrite, UInt,1, UInt,1 )

  VarSetCapacity( STARTUPINFO, 68, 0  )      ; STARTUPINFO          ;  http://goo.gl/fZf24
  NumPut( 68,         STARTUPINFO,  0 )      ; cbSize
  NumPut( 0x100,      STARTUPINFO, 44 )      ; dwFlags    =>  STARTF_USESTDHANDLES = 0x100 
  NumPut( hPipeWrite, STARTUPINFO, 60 )      ; hStdOutput
  NumPut( hPipeWrite, STARTUPINFO, 64 )      ; hStdError

  VarSetCapacity( PROCESS_INFORMATION, 16 )  ; PROCESS_INFORMATION  ;  http://goo.gl/b9BaI      
  
  If ! DllCall( "CreateProcess", UInt,0, UInt,&sCmd, UInt,0, UInt,0 ;  http://goo.gl/USC5a
              , UInt,1, UInt,0x08000000, UInt,0, UInt,0
              , UInt,&STARTUPINFO, UInt,&PROCESS_INFORMATION ) 
   Return "" 
   , DllCall( "CloseHandle", UInt,hPipeWrite ) 
   , DllCall( "CloseHandle", UInt,hPipeRead )
   , DllCall( "SetLastError", Int,-1 )     

  hProcess := NumGet( PROCESS_INFORMATION, 0 )                 
  hThread  := NumGet( PROCESS_INFORMATION, 4 )                      

  DllCall( "CloseHandle", UInt,hPipeWrite )

  AIC := ( SubStr( A_AhkVersion, 1, 3 ) = "1.0" )                   ;  A_IsClassic 
  VarSetCapacity( Buffer, 4096, 0 ), nSz := 0 
  
  While DllCall( "ReadFile", UInt,hPipeRead, UInt,&Buffer, UInt,4094, UIntP,nSz, UInt,0 )
   sOutput .= ( AIC && NumPut( 0, Buffer, nSz, "UChar" ) && VarSetCapacity( Buffer,-1 ) ) 
              ? Buffer : %StrGet%( &Buffer, nSz, "CP936" )
              ; ? Buffer : %StrGet%( &Buffer, nSz, "CP850" )
 
  DllCall( "GetExitCodeProcess", UInt,hProcess, UIntP,ExitCode )
  DllCall( "CloseHandle", UInt,hProcess  )
  DllCall( "CloseHandle", UInt,hThread   )
  DllCall( "CloseHandle", UInt,hPipeRead )

Return sOutput,  DllCall( "SetLastError", UInt,ExitCode )
}