Message Queue Process Communication

Reference: http://www.linuxidc.com/Linux/2011-08/39738.htm

# Include <sys/types. h>
# Include <sys/IPC. h>
# Include <sys/msg. h>
# Include <stdio. h>
# Include <stdlib. h>
# Include <unistd. h>
# Include < String . H>
 # Define Bufsz512
 Struct Message { //  Message structure  
      Long Msg_type;
 Char Msg_text [bufsz];
};

 Int Main ()
{
 Int Qid;
Key_t key;
 Int Len;
 Struct Message MSG;

 If (Key = ftok ( "  .  " , ' A  ' ) =- 1 ) //  Ftok gets a key  
 {
Perror ( "  Ftok  " );
Exit ( 1 );
}
 If (Qid = msgget (Key, ipc_creat | 0666 ) =-1 ){ //  Create a Message Queue  
 Perror ( "  Msgget  " );
Exit ( 1 );
}
Printf ( "  Opened queue % d \ n  " , Qid );
Puts ( " Please enter the message to queue:  " );
 If (Fgets (msg. msg_text, bufsz, stdin) = NULL) //  Get input from standard input  
 {
Puts ( "  No message  " );
Exit ( 1 );
}
MSG. msg_type = getpid ();
Len = strlen (msg. msg_text );
 If (Msgsnd (qid, & MSG, Len, 0 ) < 0 ){ //  Send message  
 Perror ( "  Message posted  " );
Exit ( 1 );
}
 If (Msgrcv (qid, & MSG, bufsz, 0 ,0 ) < 0 ){ //  Receive messages  
 Perror ( "  Msgrcv  " );
Exit ( 1 );
}
Printf ( "  Message is: % s \ n  " , (& MSG)-> msg_text );
If (Msgctl (qid, ipc_rmid, null) < 0 ){ //  Delete message  
 Perror ( "  Msgctl  " );
Exit ( 1 );
}
Exit ( 0 );
}

End