Deleting ALL message queue Post: 73441

Sponsored Content

Top Forums Programming Deleting ALL message queue Post 73441 by Perderabo on Wednesday 1st of June 2005 10:51:26 AM

06-01-2005

Administrator Emeritus

The best way to get a systemwide list of the message queues is via popen("ipcs -q", "r") but that's not what you want to hear. Programs like ps, sar, vmstat, etc cannot be portably written. You must not realize this, or you would have broken with tradition and mentioned your specific OS as you posed the question.

With standard System V release 4, you would run namelist(3) on the kernel to obtain the address of msginfo. You would then open(2) /dev/kmem, lseek(2), to that address, and read(2) the data structure. You would know the the layout of the data structure because it is somewhere in /usr/include/sys.

This exact sequence of operations is not likely to work on modern OS's, even those based on System V, release 4. Some vendors do not want to support stuff like this and worked hard to render it impossible with a little bit of success. Others have fiddled greatly with the OS and different techniques must now be employed. In general, you need to obtain the source code for your OS, view ipcs.c and copy what it does.

Perderabo

View Public Profile for Perderabo

Find all posts by Perderabo

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

Unix message Queue

Hi, I am working closly with unix message queues i have encountered the following - after creating the Q and start working with it (pushing & pulling) i receive the following stange parameters on the q's - STIME=no_entry Qnum=0 CBYTES=4140 when this happens, the Q is disabled (meaning i...

2. Programming

a message queue question..

Hi there: Thanks first. When I use a message queue amony severl processes, will I have to synchronize the queue? I don't think I would have to because a message queue is implemented in a link listed. Correct me If I am wrong...

3. Programming

Message Queue Problem Again..

Is there any way one can delete , say , a particular message from a message queue on system V?

4. IP Networking

message queue problem

I am sending and retriving the message to the queue the problem is after retrieving the message can i see what is there in my message queue. (actually in my application i am encountring some garbage value) so i want to retieve this garbage value and also want to know its size how...

5. Programming

Message Queue with fork() help

hi all... ive been trying this program where i spawn 4 threads... and i am trying to use message queue to send msgs from 3 of the threads to the parent thread... but it doent seem to be working... ive almost pulled out my hair tryin to fix the prob :confused: another wierd thing...

6. Programming

message queue

Hello, i need to write a message queue "chat server", that should work only localy. Can anyone please help me with some ideas and peshaps code. I'm studying the UNIX IPC mechanisms right now. So far, i understand how it works but i still cannot get an idea how to write a chat programm... ...

7. Programming

How to limit max no of message in a posix message queue

Hii can anyone pls tell how to limit the max no of message in a posix message queue. I have made changes in proc/sys/fs/mqueue/msg_max But still whenever i try to read the value of max. message in the queue using attr.mq_curmsgs (where struct mq_attr attr) its giving the default value as 10....

8. Programming

Message Queue Problem

Hi all, I need help about message queues, i have a server-client program that communicates each other via msg queue, firstly server opens its msg queue and waits for msg then client opens server msg queue and its own msg queue(for receiving msg from server,clients sends msg to server msg...

9. Programming

UNIX Message Queue

Hello !!!!! I have a simple question but i can't find the answer anywhere hope to meet it here. Why it is a bad idea to pass pointers through message queues ? Most structs i see all of their char types are arrays... Is it becase having pointers means we could possibily send wrong bytes ? For...

10. Ubuntu

Message Queue in Linux

Hello How can I see the created message queues in the system?

LEARN ABOUT LINUX

ipcs

IPCS(1) 						     Linux Programmer's Manual							   IPCS(1)

NAME

       ipcs - provide information on ipc facilities

SYNOPSIS

       ipcs [-asmq] [-tclup]
       ipcs [-smq] -i id
       ipcs -h

DESCRIPTION

       ipcs provides information on the ipc facilities for which the calling process has read access.

       The -i option allows a specific resource id to be specified.  Only information on this id will be printed.

       Resources may be specified as follows:

       -m     shared memory segments

       -q     message queues

       -s     semaphore arrays

       -a     all (this is the default)

       The output format may be specified as follows:

       -t     time

       -p     pid

       -c     creator

       -l     limits

       -u     summary

SEE ALSO

       ipcrm(1), ipcmk(1)

CONFORMING TO

       The  Linux  ipcs  utility is not fully compatible to the POSIX ipcs utility.  The Linux version does not support the -b and -o options, but
       does support the -l and -u options not defined by POSIX. The portable application shall not use the -a, -b, -o, -l, and -u options.

AUTHOR

       krishna balasubramanian (balasub@cis.ohio-state.edu)

AVAILABILITY

       The ipcs command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

Linux 0.99							  9 October 1993							   IPCS(1)

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

Unix message Queue

Discussion started by: kel

2. Programming

a message queue question..

Discussion started by: yanhu

3. Programming

Message Queue Problem Again..

Discussion started by: satansfury

4. IP Networking

message queue problem

Discussion started by: ramneek