c - 如何写入命名管道而不是等待读取管道

Question

我正在写入管道，直到用户输入字符串“end”。如果用户输入字符串“end”，我想更进一步。在这里我必须关闭管道并打印消息“After Written to Pipe”。但即使我输入了“结束”字符串，它也没有打印“写入管道后”这一行。即使没有读取管道的进程，我如何关闭管道并走得更远？..

你好，这是我的代码。，

int main() {
int fd;
char *b, *c;
printf("Enter Str : ");
b = malloc(50);
gets(b);

while(strcmp(b,"end")!=0){
    if(access("MSG",F_OK) != -1)    // check pipe is already available.
    {
        fd = open("MSG", O_WRONLY);
        write(fd, b, strlen(b) );
    }
    else
    {
        if( mkfifo("MSG", 0666) != -1)  // create pipe if not available.
        {
            fd = open("MSG", O_WRONLY);
            write(fd, b, strlen(b) );               
        }
    }
    printf("Enter Str : ");
    gets(b);
}   
close(fd);
printf("After Written to Pipe");

}

Answer 1

来自mkfifo(3)手册页:

However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO for reading normally blocks until some other process opens the same FIFO for writing, and vice versa.

上面这段话的意思是write会阻塞，直到有人从FIFO中读取，这就是你在你的程序中看到的。