file.cpp

一个演示多线程中共享文件操作符的例子。file是主线程

#include <cstdio>
#include <sys/stat.h>
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>
#include <sys/types.h>

using namespace std;
int main(int argc, char *argv[])
{
   int fd;
   int n;
   const char*mark = "This is parent process write.";
   char *str;

   if (argc != 2){
      cout << "Usage: ex1 <filename> " << endl;
      exit(0);
   }
   fd = open(argv[1],O_RDWR | O_CREAT | O_TRUNC ,   S_IRUSR | S_IWUSR);  
   if(fd == -1){
      perror("open error");
      exit(1);
   }
   n=fcntl(fd,F_GETFD,0);
   if (n == -1) 
   {
      perror("fcntl F_GETFD error");
      exit(1);
   }
   n = write(fd,mark, strlen(mark));
   if (n == -1) 
    {
      perror("write mark error");
      exit(1);
    }

//   if (fork()== 0)
   

   n =sprintf(str,"%d",fd);
   if (n == -1) 
    {
      perror("sprintf error");
      exit(1);
    }


　　execlp("./child", str,NULL);

   return 0;
}