ipc.c

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#include<sys/types.h>

#define SEGSIZE 100
int main(int argc, char*argv[])
{
  int shmid;
  key_t key;
  char*segptr;
  char buff[]="Hello,How are you?";
  key=ftok(".",'s');
  if((shmid=shmget(key,SEGSIZE,IPC_CREAT|IPC_EXCL|0666))==-1)
  {
    if((shmid=shmget(key,SEGSIZE,0))==-1)
    {
      perror("shmget");
      exit(1);
    }
  }
  else
  {
    printf("Creating a new shared memory segment\n");
    printf("SHMID : %d\n",shmid);     
  }
 system("ipcs -m");
  if((segptr=(char*)shmat(shmid,0,0))==(char *)-1)
  {
    perror("shmat");
    exit(1);
  }
  printf("Writing data to the shared meomry...\n");
  strcpy(segptr,buff);
  printf("DONE\n");
  
  printf("Reading data from the shared meomry...\n");
  printf("DATA:%s\n",segptr);
  printf("DONE\n");
  
  if(shmdt(segptr)==-1)
  {
    perror("shmdt");
    exit(1);
  }
  printf("Removing shared meomry segment...\n");
  if(shmctl(shmid,IPC_RMID,0)==-1)
  {
    printf("Can't remove shared memory segment...\n ");
  }
  else
  {
    printf("Removed successfully.\n");
  }
  return 0;
}