test4.c

这个是学习嵌入式开发的重要例子

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

int main(int argc, char **argv)
{
  fprintf(stdout, "Self process id(pid) = %d\n", getpid());
  fprintf(stdout, "Parent process id(ppid) = %d\n", getppid());

#if 0
  // Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and errno set to  indicate the error.
  if (setuid(0) == 0)
  {
    fprintf(stdout, "setuid(0) successed.");
  }
  else
  {
    fprintf(stdout, "setuid(0) failed: %s\n", strerror(errno));
  }
#endif

  fprintf(stdout, "uid = %d\n", getuid());
  fprintf(stdout, "euid = %d\n", geteuid());

  fprintf(stdout, "gid = %d\n", getgid());
  fprintf(stdout, "egid = %d\n", getegid());

  return 0;
}