[应用相关] 进程间通讯 小总结

#include<unistd.h>

#include<errno.h>

#include<stdio.h>

#include<stdlib.h>

#include<sys/types.h>

int main()

{

  int pipe_fd[2];

  pid_t  pid;

  char buf_r[100];

  char* p_wbuf;

  int r_num;

  memset(buf_r,0,sizeof(buf_r));

  if(pipe(pipe_fd)<0)

  {

    printf("pipe creat fail\n");

    return -1;

  }

  if((pid=fork())==0)

  {

     close(pipe_fd[1]);

     sleep(2);

     if((r_num=read(pipe_fd[0],buf_r,100))>0)

     {

         printf("%d numbers read from the pipe is %s\n",r_num,buf_r);

     }

    close(pipe_fd[0]);

    exit(0);

  }

  else if(pid>0)

  {

    close(pipe_fd[0]);

    if(write(pipe_fd[1],"hello",5)!=-1)

         printf("parent write1 hello!\n");

    if(write(pipe_fd[1],"pipe",5)!=-1)

         printf("parent write2 pipe!\n");

    close(pipe_fd[1]);

    sleep(3);

    waitpid(pid,NULL,0);

    exit(0);      

   }

}

fifo_read.c

#include<sys/types.h>

#include<sys/stat.h>

#include<errno.h>

#include<fcntl.h>

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#define FIFO  "/home/lm/myfifo"

void main()

{

     char  buf_r[100];

     int fd;

     int nread;

     

     if((mkfifo(FIFO,O_CREAT|O_EXCL)<0)&&(errno!=EEXIST))

         printf("cannot creat fifoserver\n");

     printf("prepareing for reading bytes....\n");

     memset(buf_r,0,sizeof(buf_r));

     

     fd=open(FIFO,O_RDONLY|O_NONBLOCK,0);

     if(fd==-1)

     {

         perror("open");

         exit(1);

     }

     while(1)

    {

      memset(buf_r,0,sizeof(buf_r));

      if((nread=read(fd,buf_r,100))==-1)

      {

          if(errno==EAGAIN)

               printf("no data yet\n");

      }

      printf("read %s from FIFO\n",buf_r);

      sleep(1);

    }

   pause();

   unlink(FIFO);

}

fifo_write .c

#include<sys/types.h>

#include<sys/stat.h>

#include<errno.h>

#include<fcntl.h>

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#define FIFO_SERVER  "/home/lm/myfifo"

main(int argc,char** argv)

{

     char  w_buf[100];

     int fd;

     int nwrite; 

     fd=open(FIFO_SERVER,O_WRONLY|O_NONBLOCK,0);

     if(argc==1)

     {

         printf("please send something\n");

         exit(-1);

     }

    strcpy(w_buf,argv[1]);

     if((nwrite=write(fd,w_buf,100))==-1)

      {

          if(errno==EAGAIN)

          printf("the FIFO has not been read yet,please try later\n");

      }

      else

      printf("write %s to the FIFO\n",w_buf);    

}