multi-threaded compiling

Hi,

I'd like to compile a project of mine using multiple logical cores.

I've attached the problem. It consists of two parts:

1) multi-threaded bash script and / or multi-threaded Makefile

Running bash script functions as expected, but executing the same line of
code with make and / or the command line, does not function. Perhaps
someone could explain to me why?

2) passing a string argument from a bash script and / or Makefile to the
gcc -D option

Running the makefile functions as expected, but I have not been able to get
similar code to work from a bash script. Can someone please explain to me
what I'm doing wrong?

Hope to hear from you soon.

Best regards,
Mischa Baars.