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Full Discussion: message queues
Top Forums UNIX for Advanced & Expert Users message queues Post 302228868 by tolkki on Monday 25th of August 2008 05:16:20 PM
Old 08-25-2008
message queues

#include <sys/ipc.h>
#include <sys/msg.h>

int main()
{
int qid;
int t;
struct msgbuf mesg;
qid=msgget(IPC_PRIVATE,IPC_CREAT);
mesg.mtype=1L;
mesg.mtext[0]=1;
t=msgsnd(qid,&mesg,1,0);
printf("%d",t);
}

the program prints -1 as the result of msgsnd ,which means that msgsnd doesn't work...any ideas??
 

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MESG(1) 						    BSD General Commands Manual 						   MESG(1)

NAME
mesg -- display (do not display) messages from other users SYNOPSIS
mesg [n | y] DESCRIPTION
The mesg utility is invoked by a user to control write access others have to a terminal device. Write access is allowed by default, and pro- grams such as talk(1) and write(1) may display messages on the terminal. The first terminal device in the sequence of devices associated with standard input, standard output and standard error is affected. The following options are available: n Disallow messages. y Permit messages to be displayed. If no arguments are given, mesg displays the present message status to the standard output. EXIT STATUS
The mesg utility exits with one of the following values: 0 Messages are allowed. 1 Messages are not allowed. >1 An error has occurred. EXAMPLES
Disallow messages from other users to the current terminal: mesg n Allow messages from other users to ttyp1 (assuming you are also logged in on that terminal): mesg y </dev/ttyp1 COMPATIBILITY
Previous versions of the mesg utility wrote the message status to the standard error output and affected the terminal attached to standard error without first trying the standard input or output devices. SEE ALSO
biff(1), talk(1), wall(1), write(1) STANDARDS
The mesg utility conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
A mesg command appeared in Version 1 AT&T UNIX. BSD
May 5, 2002 BSD
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