一、子进程继承父进程的普通文件描述符

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>

int main()
{
	char buf[1024]={0};
	pid_t pid;
	int ret=0;

	int fd = open("./temp.txt", O_CREAT|O_TRUNC|O_RDWR, 0666);
	if( fd == -1 ){
		perror("open ./temp.txt");
		return -1;
	}
    
	if ((pid = fork()) < 0) {
		perror("fork");
		return -1;
	} 
	else if (pid == 0) {	//child process
		sleep(1);
		ret = sprintf(buf, "child process pid:%d,parent pid:%d\n", getpid(), getppid());
		write(fd, buf, ret);
		close(fd);
		exit(0);
	}
	else {					//parent process
		ret = sprintf(buf, "parent process pid:%d, child pid:%d\n", getpid(), pid);
		write(fd, buf, ret);
		close(fd);
	}	

	waitpid(pid, NULL, 0);
	
	return 0;
}#include <stdio.h>
#includ