init.c

   1 // init: The initial user-level program
   2
   3 #include "types.h"
   4 #include "stat.h"
   5 #include "user.h"
   6 #include "fcntl.h"
   7
   8 char *argv[] = { "sh", 0 };
   9
  10 int
  11 main(void)
  12 {
  13   int pid, wpid;
  14
  15   if(open("console", O_RDWR) < 0){
  16     mknod("console", 1, 1);
  17     open("console", O_RDWR);
  18   }
  19   dup(0);  // stdout
  20   dup(0);  // stderr
  21
  22   for(;;){
  23     printf(1, "init: starting sh\n");
  24     pid = fork();
  25     if(pid < 0){
  26       printf(1, "init: fork failed\n");
  27       exit();
  28     }
  29     if(pid == 0){
  30       exec("sh", argv);
  31       printf(1, "init: exec sh failed\n");
  32       exit();
  33     }
  34     while((wpid=wait()) >= 0 && wpid != pid)
  35       printf(1, "zombie!\n");
  36   }
  37 }