- FIFO通信（first in first out）
FIFO 有名管道，实现无血缘关系进程通信。
----创建一个管道的伪文件
a.mkfifo testfifo 命令创建
b.也可以使用函数int mkfifo(const char *pathname, mode_t mode);
----内核会针对fifo文件开辟一个缓冲区，操作fifo文件，可以操作缓冲区，实现进程间通信–实际上就是文件读写
man 3 mkfifo
#include <sys/types.h>
#include <sys/stat.h>
int mkfifo(const char *pathname, mode_t mode);
注意事项：
FIFOs
Opening the read or write end of a FIFO blocks until the other end is also opened (by another process or thread). See
fifo(7) for further details.
打开fifo文件时候，read端会阻塞等待write端open，write端同理，也会阻塞等待另外一段打开。
代码示例：
file_w.c 写端
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>int main(int argc, char *argv[]) {if(argc != 2) {printf("./a.out filename1\n");return -1;}printf("begin open w\n");int o_ret = open(argv[1], O_WRONLY);printf("end open w\n");char buf[256];int num = 0;while (1) {memset(buf, '\0', sizeof(buf));sprintf(buf, "xiaoming--%d", num++);printf("strlen(buf) = %d\n", strlen(buf));write(o_ret, buf, strlen(buf));sleep(1);}close(o_ret);return 0;
}
file_r.c 读端
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>int main(int argc, char *argv[]) {if(argc != 2) {printf("./a.out filename1\n");return -1;}printf("begin open r\n");int o_ret = open(argv[1], O_RDONLY);printf("end open r\n");char buf[256];int num = 0;while (1) {memset(buf, '\0', sizeof(buf));read(o_ret, buf, sizeof(buf));printf("strlen(buf) = %d\n", strlen(buf));printf("read is%s\n", buf);}close(o_ret);return 0;
}
