I am implementing an IPC mechanism using message queues (Sys V).I can receive the messages using msgrcv() function. I am wondering how can I listen on the new messages. I would like to implement a mechanism that would notify me when there is a new message in the queue for me and I will call the msgrcv() function to retrieve the message.
View 4 RepliesI have this daemon I'm writing in Python, but I still a Python n00b. I've coded the part of the daemon that does the work, but not the part that receives messages. I need a simple system so that other processes on the same (Linux) computer can occasionally send text-string messages to the daemon (without needing to stay running all the time themselves). Once in the past we did something similar by (mis)using pyliblo to listen for OSC messages coming in on a certain port. That option isn't as workable here because the pyliblo interface (as near as I can tell) requires you to know in advance specifically what messages you are expecting, and forward them to specified functions, rather than just allowing you to generically process incoming messages as you see fit.
View 1 Replies View Relatedrecently I had been to interview where I had a question to be answered, that what are advantages and disadvantages when desiging an application in linux.
View 1 Replies View RelatedI have a pthread waiting forever on a POSIX message queue and then call mq_close and mq_unlink on the POSIX message queue. I've found that the pthread never wakes up from it's call to mq_receive and remains blocked indefinitely. Is there a way to wakeup all pthreads blocked on a POSIX message queue after calling mq_close/mq_unlink? The goal is to include error handling during message queue deletion to avoid leaving any pthreads blocked forever.
View 2 Replies View RelatedI want to communicate between two threads, each belonging to a different process. Iam using message queues for this. I use mq_open()call. I created the queues with the same queue name starting with a '/'. But when I open the queue, the queue ID is different in both the process. What should I do so that both the process have the same queue ID?
View 1 Replies View RelatedI was trying to use Message Queues for sending message from aninserted kernel module to user space. The function sys_msgsnd failedgiving the obvious error -EFAULT.However, I was able to send the message from kernel to user space when I had made the same driver part of kernel (and not inserting it).How is that possible?I am using linux.2.6.19.x (arch=ppc)I now use Netlink socket to communicate from kernel to user, but the aboveproblem seemed strange to me.
View 2 Replies View Relatedi am working on a project that uses message queues. i am able to successfully create them and they are working fine. now the problem is to close/remove message queues without software or mq_close / mq_unlink command. earlier when i worked on rh9, there is ipcs utility. we use ipcs to see all the existing message queues and ipcrm to remove them. however ipcs is not working for message queues in RHEL 5.3. Neither ipcs shows the exisiting message queues and neither we are able to use ipcrm. Plz guide to close/remove the queues with ipcs or any other command/utility from shell itself.
View 1 Replies View RelatedI'm using the Posix's mutexes in a project. I have 3 threads and 3 queues. The problem is: I used the mutexes to "protect" the access to the queues. But the first started thread monopolizes the use of the queues. See a example code:
[Code].....
I am learning network prgramming in linux in c,and try to build a server and in this server I want to bind the listening socket to a paricular Ip address and port.Bind function is showing error,I did not want to use wild card. Here is the code.
#include<stdio.h>
#include<sys/socket.h>
#include<strings.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<string.h>
[Code]...
We are trying to create a message forwarder program that receive a message on Port A and pass it on t Port B. Also receive a message from Port C and Pass it on to Port D as follows.
[Code]...
i have problem in socket programming, while displaying received message in file,i got a problem... i cant able to write it in the file.... this is the code....
Code:
/* tcpserver.c */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
[Code]....
now my problem is run time error i can able to create file but i cant able to write file....log.txt contain nothing.... as here i have give sample code... dont say not initialising function and all.... i have initialised , please only see func1() - my problem is only not able to write msg which i got received from the client..
Anyone know of the simple (!) command syntax to : a) download the full SQF tree from [URl].. b) maintain that tree WITHOUT having to download the whole dang thing again.
I'm 100% certain this is possible - that's exactly what source-code repository tools like subversion and git are supposed to do. But Git is complex and that site doesn't seem to have an obvious (to me) method of doing part b)
I have an Ubuntu Server running CUPS-PDF successfully. The problem that I am running into now is that we want to have different CUPS-PDF queues.Example:Joe from Finance wants his PDF prints to go to /home/finance which is samba shared out to all users in Finance. Mark from Operations needs logs printed out to /home/ops which is samba shared to all users in Operations and must be landscape.Finance and Operations print from the command line (lp -d print-queue filename) on the server via ssh since their app runs from a terminal.
I have looked and looked all over the net and through the cups-pdf documentation to see if there is a way to force the URI for the cups-pdf print queue instead of it going to the default of $HOME/Desktop as stated in my /etc/cups/cups-pdf.conf file. Basically, I want to set up a cups pdf printer called Finance, Advert and Ops that has all the options they need so when they print something from the linux applications, and they tell it to print to the virtual printer that they have permission to use and it go to the respective directory that they have access too.
I am trying to set up a print server here on a Squeeze system using the stock debian CUPS package. It seems that since Apple has bought this package, it has caused me nothing but grief. I have set up two different USB printers with raw print queues, and every time I send a print job to either of them, the job disappears into thin air, with no error output. In fact, when I look at the queue, it says the job was completed successfully. I look at the logs, and there is no output indicating any issues. Just for kicks, I reconfigured one of the printers to use a linux driver, and it printed just fine (a little slow, but fine). I set it back to raw, and the jobs disappear again into oblivion.
I have done this many times in the past, and never had any issues -- I even had this very same printer set up that way about a year ago, and it worked great. The only noteworthy thing that seems to have changed is that there are no longer any files called "mime.types" and "mime.convs". It seems they have been replaced by "raw.types" and "raw.convs". The contents of these two files are as follows:
raw.types: application/octet-stream
I have a fairly standard Exim setup for inbound and outbound mail. Recently our development team has put together a PHP app that allows us to send out bulk mails to our clients. The PHP app uses standard PEAR libraries to initiate an SMTP connection to localhost (application and mail server are on the same box). The idea here is that the application will send out roughly 10'000 emails in a very short time period (60 seconds or so) which Exim will then hold in its queue for delivery.
The problem comes in where after about 50 emails, Exim stops accepting mail and loggs the following error in the exim_main.log file: SMTP command timeout on connection from localhost [127.0.0.1] Could it be that this is because Exim immediately starts delivering the mail and then stops accepting new incoming connections? I thought that increasing the SMTP limits may be the problem here, but even after setting new values in the exim.conf file to the following, I still get the same problem:
queue_run_max = 5000
smtp_accept_max = 5000
smtp_accept_queue = 5000
This begs two questions: How do I resolve this? What is the best way for configuring Exim to accept a huge amount of mail into the queue in a very short time period, but then gradually delivery it once it's all in the queue? I've seen some people run separate Exim daemons for incoming and outgoing mail; is this a good solution?
am using a PC104 with Linux and i need to control it with a controller that is connected via RS-232 or USB port. I need to launch one or more application some specific message come through RS-232 port. Is that doable? If yes how? I am beginner with C++ on Linux so i don't really know specif libraries. If possible i would like to use pure C and not C++.
View 4 Replies View Relatedcan i just copy/backup postfix mail queues in /var/spool/postfix and paste that folder back in after i done migrating all users and mails to a new mailserver?
View 3 Replies View RelatedI want to send a message from IP to Another IP through command prompt. how can i do this.s
View 3 Replies View RelatedI need some direction on a small scripting question. I've been doing some development and storing the code on a network drive with multiple user access. My development is getting complex enough that it is time to set up a svn repo for it. I would like to set up a little script (if possible) that prints a message/reminder to whomever is accessing the code directory stating that the code is ultimately stored in svn and any changes need to be checked in, etc. Is there a way to have linux print a message to the screen based on a 'cd /specific_dir/' command? So far google is mum on the topic. Using Debian and bash shell.
View 5 Replies View RelatedI'm facing a scenario in which i need to block messages from being passed onto a message queue when my code is running. how to proceed.
View 8 Replies View RelatedMy level is starter with Ubuntu. Moderate experience with C.Problem starting with programming in C under Ubuntu.I have installed Anjuta IDE and made this classical program.
#include "stdio.h"
main()
{
[code]....
- how to add the date/time to the email (message body)
- how to as the user to add a picture
- how add on an error page a button to send it back to the form so that the input does not get lost
Here the program so far:
<?php
/*
CHFEEDBACK.PHP Feedback Form PHP Script Ver 2.15.0
Generated by thesitewizard.com's Feedback Form Wizard 2.15.0.
[code]....
How to communicate between two threads using message queue?
View 4 Replies View Relatedi trying to add text messge in textarea and i got error in connection and i don't know if it correct syntax. and i wonder when i was install xamp server it no password required. but i dont know what password that i input in my php connection.?
PHP Code:
<?php
$con�=�mysql_connection("localhost","root","123");
if(!$con)
{
[code]....
PHP Code:
<textarea�rows="3"�cols="30"�name="txtcomment"�wrap="physical">Leave�a�Comment
i have a client and server program in C. in that program server is requesting some parameters from client (like systems up time, total memory, no of process running etc).for this i used switch statements. but the problem i am having with this is that,
1. it is always going in default case on client side.2. and i also want my program to send requests/messages to client periodically. means after some interval (say after every 2,3 mins) server sends next request to client.
I am trying to create a socket server in user space and a client in kernel space and send big messages (a little over 64kbytes) between them.
I used an kernel socket programming examplefrom this link - url for the kernel client side.
When the client in kernel side sends out a 64k message, usually, the server side in the user space will get a big part of the message, but will stuck at waiting for the recv() to return to get the rest of it. So I am chopping the packets into small pieces, 1000 bytes each to send to the server. But only some times, the packets will all arrive at the server/receiver side, and the server and assemble the whole message. Many times, the server is stuck at waiting for the last a couple of byte from the sending side. From the sending side printk log, it has already sent every thing.
I am attaching some log here, and the code at the end. Can someone give me some idea on how to force the data to arrive at the receiver side? Maybe the kernel on the receiver side is holding part of the packet so
the receiver program in the user space is blocked at recv()? I tried adding TCP_NODELAY on sockets on both sender and receiver sides, both it did not help.
I got a connection from (10.16.216.217 , 1489)
- Server side stuck on recv()-
bytes_recieved 17384
bytes_recieved 32768, total received 50152, expected 65540
- Client side is already done -
code....
Following function obtains the system-maintained structure for a message queue:
Code:
And following function simply resizes a message queue to a user-defined value, namely, "size":
Code:
My question is if there is a theoretical limit on user-defined message queue sizes.
To put in other words, is it possible to increase the default message queue size to any user-defined value as long as that certain value does not exceed the size of system's physical memory ?
I use 64-bit Ubuntu 9.04.
why the message string isn�t output to the Applet window in the code below?
Code:
import javax.swing.*;
class printit extends JApplet {
[code].....
I just wrote a simple perl script to compare the following two files
[Code]...
I have a problem when using awk:
e.g: awk '{processing text}' File1 > File2
But when I'm processing the File1, I want to print out some messages to the screen (not the File2). How can I do that?