2.9BSD - /usr/src/cmd/sleep.c

   1: main(argc, argv)
   2: char **argv;
   3: {
   4:     int c, n;
   5:     char *s;
   6: 
   7:     n = 0;
   8:     if(argc < 2) {
   9:         printf("arg count\n");
  10:         exit(0);
  11:     }
  12:     s = argv[1];
  13:     while(c = *s++) {
  14:         if(c<'0' || c>'9') {
  15:             printf("bad character\n");
  16:             exit(0);
  17:         }
  18:         n = n*10 + c - '0';
  19:     }
  20:     sleep(n);
  21: }

Defined functions