#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
 
int main()
{
        int shmid;
        key_t key=0x1000;
 
        shmid=shmget(key,10,IPC_CREAT|0666);
        if(shmid<0)
        {
                printf("unable to create shared memory");
        }
 
        printf("shmid : %d\n",shmid);
 
        key=0x1010;
 
        shmid=shmget(key,10,IPC_CREAT|0666);
 
        printf("shmid : %d\n",shmid);
 
        shmid=shmget(IPC_PRIVATE,10,IPC_CREAT|0666);
}


Output:

[04mca8@LINTEL 04mca8]$ gcc shprog.c
[04mca8@LINTEL 04mca8]$ ./a.out
shmid : 98305
shmid : 131074