/* Using a message queue IPC */
/* Receiving process */
/* Initial variant */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <errno.h>
#define MSQSIZ 1024

struct msgbf { long mtype;
                char mtext [1024];
                    };

int main (int argc, char * argv[])

{int msid, v; int i;
 struct msgbf mess;

 if (argc != 3) {printf ("Usage: <key> <type>\n"); exit (1);}

 /* Get message queue */
 msid = msgget ((key_t) atoi (argv[1]), 0);
 if (msid == -1) {printf("Cannot get message queue\n"); exit (1);}

 /* Read  a message of the specified type from 
    the specified queue (not more than 100 bytes) */
 
 v = msgrcv(msid,(struct msgbuf *)&mess, 100, 
            atoi(argv[2]), IPC_NOWAIT);
 if (v < 0){if (errno == ENOMSG)

            printf("No given message in the queue\n");
            else
            printf ("ERROR reading from queue\n");
            }
 else printf ("[%d]  %s\n", mess.mtype, mess.mtext);

/* Now remove the message queue */
    
 if (msgctl(msid,IPC_RMID, 0) <0)
            printf("Error in removing the message queue\n");
 else       printf("Removed the message queue, with key = %ld\n", 
            atoi(argv[1]));
exit(0);
 }