How is SCons Constructing the Command Lines It Executes? the --debug=presub Option

Sometimes it's useful to look at the pre-substitution string that SCons uses to generate the command lines it executes. This can be done with the --debug=presub option:

      % scons -Q --debug=presub
      Building prog.o with action:
      cc -o prog.o -c -I. prog.c
      Building prog with action:
      cc -o prog prog.o