实验

#include<sys/types.h>

#include<sys/stat.h>

#include<errno.h>

#include<fcntl.h>

#include<stdio.h>

#include<stdlib.h>

#include<limits.h>             

 

#define MYFIFO                 "/tmp/myfifo" /* 有名管道文件名*/

#defineMAX_BUFFER_SIZE            PIPE_BUF    /*定义在于limits.h中*/

      

int main(intargc, char * argv[]) /*参数为即将写入的字符串*/

{

       int fd;

       char buff[MAX_BUFFER_SIZE];

       int nwrite;

      

       if(argc <= 1)

       {

              printf("Usage: ./fifo_writestring\n");

              exit(1);

       }

       sscanf(argv[1], "%s", buff);

      

       /* 以只写阻塞方式打开FIFO管道 */

       fd = open(MYFIFO, O_WRONLY);

       if (fd == -1)

       {

              printf("Open fifo fileerror\n");

              exit(1);

       }

      

       /*向管道中写入字符串*/

       if ((nwrite = write(fd, buff,MAX_BUFFER_SIZE)) > 0)

       {

              printf("Write '%s' toFIFO\n", buff);

       }

      

       close(fd);

       exit(0);

}

 

(2)读管道的程序

 

#include<sys/types.h>

#include<sys/stat.h>

#include<errno.h>

#include<fcntl.h>

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<limits.h>             

 

#define MYFIFO                 "/tmp/myfifo"

#defineMAX_BUFFER_SIZE            PIPE_BUF /*定义在于limits.h中*/

 

int main()

{

       char buff[MAX_BUFFER_SIZE];

       int fd;

       int nread;

      

       /* 判断有名管道是否已存在，若尚未创建，则以相应的权限创建*/

       if (access(MYFIFO, F_OK) == -1)

       {

              if ((mkfifo(MYFIFO, 0666) < 0)&& (errno != EEXIST))

              {

                     printf("Cannot createfifo file\n");

                     exit(1);

              }

       }

      

       /* 以只读阻塞方式打开有名管道 */

       fd = open(MYFIFO, O_RDONLY);

       if (fd == -1)

       {

              printf("Open fifo fileerror\n");

              exit(1);

       }

      

       while (1)

       {

              memset(buff, 0, sizeof(buff));

              if ((nread = read(fd, buff,MAX_BUFFER_SIZE)) > 0)

              {

                     printf("Read '%s' fromFIFO\n", buff);

              }           

       }    

      

       close(fd);

       exit(0);

}