Here's a bit of code from page 10:

  #include "ourhdr.h"

  int
  main(void)
  {
    printf("hello world from process ID %d\n", getpid());
    exit(0);
  }

Ch 7 is the environment of a unix process. 7.2: "argc is the number of command line arguments and argv is an array of pointers to the arguments. We describe these in Section 7.4." exit codes are discussed in section 7.3, where he also talks about 0 in exit.

Granted, he does not discuss the syntax or NULL...

Looking through it.. I'll agree it isn't a beginner book. Intermediate at worst though.