Question

#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <stdio.h>
#include <sys/ipc.h>
#include <time.h>
#include <sys/msg.h>
#include <sys/shm.h>



typedef struct{long type;char resultado[10];} MsgAnswerLoginStruct;


typedef struct{long tipo;int meupid;char login[20];char password[20];}MsgReqLoginStruct;


main(){

printf("i am here");

int msg_id, status;
MsgReqLoginStruct msg;
MsgAnswerLoginStruct msg2;

msg_id = msgget(2000, 0600 | IPC_CREAT);
if(msg_id == -1){
    printf("erro\n");
    exit(1);
}


status = msgrcv(msg_id, &msg, sizeof(msg) - sizeof(long) , 1,  0);
if(status < 0){
    printf("erro2\n");
    exit(1);
}


printf("Tentativa de Autenticação de PID = %d\n", msg.meupid);

}

here is my problem, this is a program that receives messages from the IPC, but he keeps waiting even when I am trying to send from another process..
And I put that printf to debug.. It doesnt appear on my console?! why ?
when I run program it just keeps waiting..
Thanks in advance guys!!

Answer 1

Because you are not flusing the buffer. It’s likely stdout is line buffered in your implementation.

Try:

printf("i am here\n");
                  ^^

Or

printf("i am here");
fflush(stdout);