SConscript

Import('env', 'lib')
env = env.Clone()

program = env.Program('foo', 'foo.c', LIBS=[lib])

SConstruct

env = Environment()

lib = env.Library('libfoo', 'libfoo.c')


Export('env', 'lib')

SConscript('SConscript')

transcript

$ scons --tree=all
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
gcc -o foo.o -c foo.c
gcc -o libfoo.o -c libfoo.c
ar rc libfoo.a libfoo.o
ranlib libfoo.a
gcc -o foo foo.o libfoo.a
+-.
  +-SConscript
  +-SConstruct
  +-foo
  | +-foo.o
  | | +-foo.c
  | | +-/usr/bin/gcc
  | +-/usr/bin/gcc
  | +-libfoo.a
  |   +-libfoo.o
  |   | +-libfoo.c
  |   | +-/usr/bin/gcc
  |   +-/usr/bin/ar
  |   +-/usr/bin/ranlib
  +-foo.c
  +-foo.o
  | +-foo.c
  | +-/usr/bin/gcc
  +-libfoo.a
  | +-libfoo.o
  | | +-libfoo.c
  | | +-/usr/bin/gcc
  | +-/usr/bin/ar
  | +-/usr/bin/ranlib
  +-libfoo.c
  +-libfoo.o
    +-libfoo.c
    +-/usr/bin/gcc
scons: done building targets.