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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)                                                            User Commands                                                           MESG(1)

NAME
mesg - display (or do not display) messages from other users SYNOPSIS
mesg [option] [n|y] DESCRIPTION
The mesg utility is invoked by a user to control write access others have to the terminal device associated with standard error output. If write access is allowed, then programs such as talk(1) and write(1) may display messages on the terminal. Traditionally, write access is allowed by default. However, as users become more conscious of various security risks, there is a trend to remove write access by default, at least for the primary login shell. To make sure your ttys are set the way you want them to be set, mesg should be executed in your login scripts. ARGUMENTS
n Disallow messages. y Allow messages to be displayed. If no arguments are given, mesg shows the current message status on standard error output. OPTIONS
-v, --verbose Explain what is being done. -V, --version Display version information and exit. -h, --help Display help text and exit. 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. FILES
/dev/[pt]ty[pq]? SEE ALSO
login(1), talk(1), write(1), wall(1), xterm(1) HISTORY
A mesg command appeared in Version 6 AT&T UNIX. AVAILABILITY
The mesg command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/. util-linux July 2014 MESG(1)
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