- FIFO通信（first in first out）
FIFO 有名管道，實現無血緣關系進程通信。
----創建一個管道的偽文件
a.mkfifo testfifo 命令創建
b.也可以使用函數int mkfifo(const char *pathname, mode_t mode);
----內核會針對fifo文件開辟一個緩沖區，操作fifo文件，可以操作緩沖區，實現進程間通信–實際上就是文件讀寫
man 3 mkfifo
#include <sys/types.h>
#include <sys/stat.h>
int mkfifo(const char *pathname, mode_t mode);
注意事項：
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.
打開fifo文件時候，read端會阻塞等待write端open，write端同理，也會阻塞等待另外一段打開。
代碼示例：
file_w.c 寫端
#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 讀端
#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;
}
