Inter process communication using named pipe(FIFO)

   The drawback of normal pipe is only the processes related to process that created the pipe may communicate among them. A named pipe is one which is stored in the disk and two unrelated process can communicate each other.

syntax to create name pipe:

             mknod("mypipe",S_IFIFO|0644,0);/*Syntax to create named pipe in UNIX program*/

  

         from command prompt we can create named file 

         mknod mypipe p

Inter process communication using named pipes

(execute two programs simultaneously in two command prompts. Producer will get struck until a consumer is ready to read and consumer will get struck until a producer is ready to place data.)

//producer.c

#include<stdio.h>

#include<sys/stat.h>

#include<string.h>

#include<unistd.h>

#include<fcntl.h>

#include<errno.h>

#include<stdlib.h>

#define FIFO_NAME "XYZ"

void main()

{

  int num,fd;

   char s[300];

   mknod(FIFO_NAME,S_IFIFO|0666,0);

   printf("waiting for readers\n");

   fd=open(FIFO_NAME,O_WRONLY);

   printf("got a reader type some stuff");

   while(gets(s),!feof(stdin))

   {

     if((num=write(fd,s,strlen(s)))==-1)

       perror("write");

     else

     printf("speak:wrote %d bytes\n", num);

   }

}

OUTPUT:

  waiting for readers

  got a reader type some stuff

hi hello

  speak:wrote 8 bytes

//Consumer.c

#include<stdio.h>

#include<sys/stat.h>

#include<unistd.h>

#include<sys/types.h>

#include<fcntl.h>

#include<errno.h>

#define FIFO_NAME "XYZ"

void main()

{

  char s[300];

    int num,fd;

  mknod(FIFO_NAME,S_IFIFO|0666,0);

    printf("waiting for writers\n");

    fd=open(FIFO_NAME,O_RDONLY);

    printf("got a writer\n");

    do

     {

       if((num=read(fd,s,300))==-1)

             perror("read");

        else

         {

             s[num]='\0';

             printf("read %s ",s);

         }

     }while(num>0);

}

OUTPUT:

    waiting for writers

    got a writer 

    read hi hello

IPC using named pipe, pipe, producer consumer problem, shared memory, SIGPIPE , semaphores, inter process communication