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• How to find out which python script is using resources?

  - by Jesse the Wind Wanderer

  Can someone tell me how to find out which python script is using lots of system resources? I can see with the 'top' command that a process called "python" is always near the top of the list. 2603 jesse 20 0 159m 27m 13m S 6 1.4 1:47.74 python Can someone tell me how to find this specific python script's name? I could go through the arduous process of disabling startup apps/processes until I finally found the one that starts this python process but there must be a better way of determining what exactly this python process is, yes? Doing a ps -AH doesn't yield anything useful. ps -AH 1 ? 00:00:00 init ... 1325 ? 00:00:00 lightdm 1382 tty7 00:01:57 Xorg 2265 ? 00:00:00 lightdm 2510 ? 00:00:00 gnome-session 2546 ? 00:00:00 ssh-agent 2560 ? 00:00:02 gnome-settings- 2582 ? 00:00:01 syndaemon 2578 ? 00:00:49 compiz 3009 ? 00:00:00 sh 3010 ? 00:00:01 gtk-window-deco 2590 ? 00:00:00 nm-applet 2591 ? 00:00:00 bluetooth-apple 2592 ? 00:00:00 indicator-ubunt 2593 ? 00:00:00 gnome-fallback- 2600 ? 00:00:05 nautilus 2601 ? 00:00:00 everpad 2603 ? 00:02:24 python

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• SQL SERVER – Validating Unique Columnname Across Whole Database

  - by pinaldave

  I sometimes come across very strange requirements and often I do not receive a proper explanation of the same. Here is the one of those examples. Asker: “Our business requirement is when we add new column we want it unique across current database.” Pinal: “Why do you have such requirement?” Asker: “Do you know the solution?” Pinal: “Sure I can come up with the answer but it will help me to come up with an optimal answer if I know the business need.” Asker: “Thanks – what will be the answer in that case.” Pinal: “Honestly I am just curious about the reason why you need your column name to be unique across database.” (Silence) Pinal: “Alright – here is the answer – I guess you do not want to tell me reason.” Option 1: Check if Column Exists in Current Database IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn') BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END Option 2: Check if Column Exists in Current Database in Specific Table IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn' AND OBJECT_ID = OBJECT_ID(N'tableName')) BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END I guess user did not want to share the reason why he had a unique requirement of having column name unique across databases. Here is my question back to you – have you faced a similar situation ever where you needed unique column name across a database. If not, can you guess what could be the reason for this kind of requirement?  Additional Reference: SQL SERVER – Query to Find Column From All Tables of Database Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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• How should I share variables between instances/classes?

  - by tesselode

  I'm making a game using LOVE, so everything is programmed in Lua. I've been experimenting with using classes and object orientation recently. I've found out that a nice system to use is having most of the game's code in different classes, and having a table of instances with all of the instances of any class in it. This way, I can go through every instance of every class and update and draw it by calling the same function. There is a problem, though. Let's say I have an instance of a player with variables for health and recharge time of a weapon. I also have a master instance which is responsible for drawing the HUD. How can I tell the master instance what the player's health is? Bad solutions: Assuming that the player instance will always have the same position in the table - that can be easily changed. Using global variables. Global variables are evil. Have the master instance outside of the instances table, and have the player set variables inside the master instance, which it then uses for HUD drawing. This is really bad because now I have to make a duplicate of every variable the master instance needs. What is the proper, standard way of sharing variables between instances? Do I need to change the way I keep track of instances?

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• SQL SERVER – Get Schema Name from Object ID using OBJECT_SCHEMA_NAME

  - by pinaldave

  Sometime a simple solution have even simpler solutions but we often do not practice it as we do not see value in it or find it useful. Well, today’s blog post is also about something which I have seen not practiced much in codes. We are so much comfortable with alternative usage that we do not feel like switching how we query the data. I was going over forums and I noticed that at one place user has used following code to get Schema Name from ObjectID. USE AdventureWorks2012 GO SELECT s.name AS SchemaName, t.name AS TableName, s.schema_id, t.OBJECT_ID FROM sys.Tables t INNER JOIN sys.schemas s ON s.schema_id = t.schema_id WHERE t.name = OBJECT_NAME(46623209) GO Before I continue let me say I do not see anything wrong with this script. It is just fine and one of the way to get SchemaName from Object ID. However, I have been using function OBJECT_SCHEMA_NAME to get the schema name. If I have to write the same code from the beginning I would have written the same code as following. SELECT OBJECT_SCHEMA_NAME(46623209) AS SchemaName, t.name AS TableName, t.schema_id, t.OBJECT_ID FROM sys.tables t WHERE t.name = OBJECT_NAME(46623209) GO Now, both of the above code give you exact same result. If you remove the WHERE condition it will give you information of all the tables of the database. Now the question is which one is better – honestly – it is not about one is better than other. Use the one which you prefer to use. I prefer to use second one as it requires less typing. Let me ask you the same question to you – which method to get schema name do yo use? and Why? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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• Does it make sense to write a build scripts in C++?

  - by Klaim

  I'm using CMake to generate my projects IDE/makefiles, but I still need to call custom "scripts" to manipulate my compiled files or even generate code. In previous projects I've been using Python and it was OK, but now I'm having serious trouble managing a lot of dependencies in two very big projects I'm working on so I want to minimize the dependencies everywhere. Someone suggested to me to use C++ to write my build scripts instead of adding a language dependency just for that. The projects themeselves already use C++ so there are several advantages that I can see: to build the whole project, only a C++ compiler and CMake would be necessary, nothing else (all the other dependencies are C or C++); C++ type safety (when using modern C++) makes everything easier to get "correct"; it's also the language I know the better so I'm more at ease with it even if I'm able to write some good Python code; potential gain in execution speed (but i don't think it will really be perceptible); However, I think there might be some drawbacks and I'm not sure of the real impact as I didn't try yet: might be longer to write the code (that said I'm not sure because I'm efficient enough in C++ to write something that work quickly, so maybe for this system it wouldn't be so long to write) (compilation time shouldn't be a problem for this case); I must assume that all the text files I'll read as input are in UTF-8, I'm not sure it can be easilly checked at runtime in C++ and the language will not check it for you; libraries in C++ are harder to manage than in scripting languages; I lack experience and forsight so maybe I'm missing advantages and drawbacks. So the question is: does it make sense to use C++ for this? do you have experiences to report and do you see advantages and disadvantages that might be important?

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• How do I create my own programming language and a compiler for it

  - by Dave

  I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, JavaScript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist someone like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (i.e. like Thread, Synchronization, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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• virtual install from ISO not getting virtual kernel

  - by Pete

  I have a KVM host (12.04.5) that I have been installing guests on in variety of ways. I just noticed recently one of my guests was running a generic kernel when I'm fairly certain I specified minimum virtual machine during install from a 12.04.2 server iso. From what I understand it should be running a stripped down kernel "optimized" for VMs. I set up another server to test, this time using a 14.04.1, and sure enough I ended up with uname -r returning 3.13.0-32-generic. It seems that if I use an .iso to install, I end up with generic regardless. However building with the vmbuilder ... --flavour virtual --suite precise ... (I don't have trusty available yet) script gives me an ubuntu 12.04.5 LTS system running kernel 3.2.0-67-virtual. The server FAQ mentions I should be getting the virtual kernel. What are practical advantages of using linux-image-virtual kernel? gives me the impression that it doesn't really matter functionally (in my case I only have a couple VMs running). I first thought was maybe I was somehow not applying the correct options because the installer F4 menu doesn't really give great feedback if the mode has been selected or not. Looking in the log /var/log/installers/syslog I see Command line: file=/cdrom/preceed/ubuntu-server-minimalvm.seed ... I know that I can install the virtual kernel package down the road, but why am I not, or should I be getting the virtual flavor of kernel from an ISO install when doing an minimum VM install?

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• How do I create my own programming language and a compiler for it

  - by Dave

  I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, Javascript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist some one like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (ie like Thread, Synchronisation, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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• Very large log files, what should I do?

  - by Masroor

  (This question deals with a similar issue, but it talks about a rotated log file.) Today I got a system message regarding very low /var space. As usual I executed the commands in the line of sudo apt-get clean which improved the scenario only slightly. Then I deleted the rotated log files which again provided very little improvement. Upon examination I find that some log files in the /var/log has grown up to be very huge ones. To be specific, ls -lSh /var/log gives, total 28G -rw-r----- 1 syslog adm 14G Aug 23 21:56 kern.log -rw-r----- 1 syslog adm 14G Aug 23 21:56 syslog -rw-rw-r-- 1 root utmp 390K Aug 23 21:47 wtmp -rw-r--r-- 1 root root 287K Aug 23 21:42 dpkg.log -rw-rw-r-- 1 root utmp 287K Aug 23 20:43 lastlog As we can see, the first two are the offending ones. I am mildly surprised why such large files have not been rotated. So, what should I do? Simply delete these files and then reboot? Or go for some more prudent steps? I am using Ubuntu 14.04.

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• wrong kernel running after install

  - by ticktockhouse

  I have installed Ubuntu 14.04 from unetbootin. When it reboots after the install, uname -r says: 3.5.0-17-generic ..this means that no modules have loaded for the kernel that is actually installed (3.13.0-32-generic). Does anyone know why this kernel should be installed via the install process? Is it an artifact of using Unetbootin? Booting into the Unetbootin image gives the correct kernel, and thus the modules load. Knowing why is one thing, but I'm not sure how to remedy it now. Because no modules are loaded, I can't connect to the network or connect a USB drive. I've tried update-grub, which seems to find the correct kernel, but doesn't seem to tell the system to boot from it. I've also tried selecting the kernel at boot time using the "Advanced Options for Ubuntu", and the 3.13.x kernel is the only one listed. Selecting this lead to the 3.5.x kernel stubbornly loading.. I'm a fairly accomplished sysadmin, but this one has me flummoxed :) Can anyone help?

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• Ask the Readers: How Do You Monitor Your Computer?

  - by Jason Fitzpatrick

  Beneath the shiny case of your computer and GUI of your operating system there’s a lot–CPU utilization, memory access, and disk space consumption to name a few things–you can keep an eye on. How do you keep an eye on resource utilization and more on your computer? Image available as wallpaper here. Whether you’re carefully managing a small pool of RAM, making sure your abundant apps don’t bog down your processor, or you just like having an intimate view of what’s going on in the guts of your computer, we want to hear all about the tools you use to do it. How and why do you monitor your computer? From disk use to case temps, any kind of monitoring is fair game. Sound off in the comments with the how and why of your monitoring arrangement and then be sure to stop back in on Friday for the What You Said roundup to see what tricks and tools your fellow readers are using to keep an eye on their hardware. HTG Explains: How Antivirus Software Works HTG Explains: Why Deleted Files Can Be Recovered and How You Can Prevent It HTG Explains: What Are the Sys Rq, Scroll Lock, and Pause/Break Keys on My Keyboard?

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• What is the program "Additional Drivers" (jockey-gtk) talking me about?

  - by Robert Vila

  The program says: "No proprietary drivers are in use on this system" But it doesn't say if it is talking about graphical drivers only or what. Then, it lists two drivers: NVIDIA accelerated graphics driver (version 173). NVIDIA accelerated graphics driver (version current) [recomended] Both have exactly the same description. What is the difference then? When I select the 1st one, it says: "This river is not activated",and there's a button to "activate" it. When I select the 2nd one, it says: "This river is activated but it is not currently in use", and the button is to "remove". So which one is in use? Why or what for should I have activated (enabled) and not in use? If it is in use it is activated? What is the difference between activate and remove? and what is the relationship between installed, activated, in use, enabled and removed, disabled, inactive and not-installed? Why can I activate the inactivated and remove (but not deactivate) the activated that is not in use? All this is very puzzling... What other drivers can I use for an Apple MacBook pro 3,1 and how? I see that there's a nouveau and I heard that there was going to be a new open source even better. > -display > description: VGA compatible controller > product: G84 [GeForce 8600M GT] > vendor: nVidia Corporation

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• Does it make sense to write build scripts in C++?

  - by Klaim

  I'm using CMake to generate my projects IDE/makefiles, but I still need to call custom "scripts" to manipulate my compiled files or even generate code. In previous projects I've been using Python and it was OK, but now I'm having serious trouble managing a lot of dependencies in two very big projects I'm working on so I want to minimize the dependencies everywhere. Someone suggested to me to use C++ to write my build scripts instead of adding a language dependency just for that. The projects themeselves already use C++ so there are several advantages that I can see: to build the whole project, only a C++ compiler and CMake would be necessary, nothing else (all the other dependencies are C or C++); C++ type safety (when using modern C++) makes everything easier to get "correct"; it's also the language I know the better so I'm more at ease with it even if I'm able to write some good Python code; potential gain in execution speed (but i don't think it will really be perceptible); However, I think there might be some drawbacks and I'm not sure of the real impact as I didn't try yet: might be longer to write the code (that said I'm not sure because I'm efficient enough in C++ to write something that work quickly, so maybe for this system it wouldn't be so long to write) (compilation time shouldn't be a problem for this case); I must assume that all the text files I'll read as input are in UTF-8, I'm not sure it can be easilly checked at runtime in C++ and the language will not check it for you; libraries in C++ are harder to manage than in scripting languages; I lack experience and forsight so maybe I'm missing advantages and drawbacks. So the question is: does it make sense to use C++ for this? do you have experiences to report and do you see advantages and disadvantages that might be important?

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• not being able to access any sudo function on my pc

  - by explorex

  Hi, I am not being to access any functions in my desktop and I don't have an OS besides Ubuntu 10.04 Lucid Linux and I am new to ubuntu. I think I rebooted my computer thinking that Google Chrome crashed. I opened Google Chrome but it showed opening message but never opened so I restarted my computer. and when my system was loading ('i was playing with keyboard dont know what I typed') and when by ubutnu loaded, I was unable to access anything some of characteristics are listed below I cannot hear any sound I cannot access wired ethernet connection on the right corner where I usually enable to access interne and I have no internet. There is no local apache server either. when ever I try to start apacer I get setuid must be root or something. When I type sudo then I get message setuid must be root. I cannot access orther external storage devices like pendrive and portable hard drive and cannot mount my other drives with FAT32 filesystem. When I try to start my apache webserver with out typing sudo then I get message cannnot open socket or something like it. EDIT:: i remember also doing command chown -R www-data / earlier and got error message EDIT:: and i cannot shutdown my computer, it only logs off

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• Entity communication: Message queue vs Publish/Subscribe vs Signal/Slots

  - by deft_code

  How do game engine entities communicate? Two use cases: How would entity_A send a take-damage message to entity_B? How would entity_A query entity_B's HP? Here's what I've encountered so far: Message queue entity_A creates a take-damage message and posts it to entity_B's message queue. entity_A creates a query-hp message and posts it to entity_B. entity_B in return creates an response-hp message and posts it to entity_A. Publish/Subscribe entity_B subscribes to take-damage messages (possibly with some preemptive filtering so only relevant message are delivered). entity_A produces take-damage message that references entity_B. entity_A subscribes to update-hp messages (possibly filtered). Every frame entity_B broadcasts update-hp messages. Signal/Slots ??? entity_A connects an update-hp slot to entity_B's update-hp signal. Something better? Do I have a correct understanding of how these communication schemes would tie into a game engine's entity system? How do entities in commercial game engines communicate?

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• WPF TextBlock refresh in real time

  - by TheOnlyBrien

  I'm new to C#, in fact, this is one of the first projects I've tried to start on my own. I am curious why the TextBlock will not refresh with the following code? The WPF window does not even show up when I add the "while" loop to the code. I just want this to have a real time display of the days since I was born. Please help me out or give me constructive direction. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace daysAliveWPF { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); DateTime myBirthday = new DateTime(1984, 01, 19); while (true) { TimeSpan daysAlive = DateTime.Now.Subtract(myBirthday); MyTextBlock.Text = daysAlive.TotalDays.ToString(); } } } } Similar code has worked in a Console Window application, so I don't understand what's going on here. Console Application code snip that did work is: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace DisplayRealTime { class Program { static void Main(string[] args) { DateTime myBirthday = new DateTime(1984, 06, 19); while (true) { TimeSpan daysAlive = DateTime.Now.Subtract(myBirthday); Console.Write("\rTotal Days Alive: {0}", daysAlive.TotalDays.ToString(".#####")); } } } } Thank you!

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• How does rc job work / order of (contradicting) "start on ..." and "stop on ..." stanzas

  - by Binarus

  Hi, I just can't understand how Upstart's rc job definition in Natty 11.04 works. To illustrate the problem, here is the definition (empty lines and comments are left out): start on runlevel [0123456] stop on runlevel [!$RUNLEVEL] export RUNLEVEL export PREVLEVEL console output env INIT_VERBOSE task exec /etc/init.d/rc $RUNLEVEL Let's suppose we currently are in runlevel 2 and the rc job is stopped (that is exactly the situation after booting my box and logging in via SSH). Now, let's assume that the system switches to runlevel 3, for example due to a command like "telinit 3" given by root. What will happen to the rc job? Obviously, the rc job will be started since it is currently stopped and the event runlevel 3 is matching the start events. But from now on, things are unclear to me: According to the manual $RUNLEVEL evaluates to the new runlevel when the job is started (that means 3 in our example). Therefore, the next stanza "stop on runlevel [!$RUNLEVEL]" translates to "stop on runlevel [!3]"; that means we have a first stanza which will trigger the job, but the second stanza will never stop the job and seems to be useless. Since I know that the Ubuntu / Upstart people won't do useless things, I must be heavily misunderstanding something. I would be grateful for any explanation. While trying to understand this, an additional question came to my mind. If I had contradicting start and stop triggers, for example start on foo stop on foo what would happen? I swear I never will do that, but I am nevertheless very interested in how Upstart handles that on the theoretical level. Thank you very much! Editing the question as a reaction on geekosaur's first answer: I can see the parallelism, but it is not that easy (at least, not to me). Let's assume the job aurrently is still running, and a new runlevel event comes in (of course, the new runlevel is different from the current one). Then, the following should happen: 1) The job is single instance. That means that "start on ..." won't be triggered since the job is currently running; $RUNLEVEL is not touched. 2) "stop on ..." will be triggered since the new runlevel is different from $RUNLEVEL, so the job will be aborted. 3) Now, the job is stopped and waiting. I can't see how it is restarted with the new runlevel. AFAIK, initctl emits events only once, so "start on ..." won't be triggered and the new runlevel won't be entered. I know that I still misunderstanding something, and I am grateful for explanations. Thank you very much!

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• Upstart: How does rc job work / order of (contradicting) "start on ..." and "stop on ..." stanzas

  - by Binarus

  Hi, I just can't understand how Upstart's rc job definition in Natty 11.04 works. To illustrate the problem, here is the definition (empty lines and comments are left out): start on runlevel [0123456] stop on runlevel [!$RUNLEVEL] export RUNLEVEL export PREVLEVEL console output env INIT_VERBOSE task exec /etc/init.d/rc $RUNLEVEL Let's suppose we currently are in runlevel 2 and the rc job is stopped (that is exactly the situation after booting my box and logging in via SSH). Now, let's assume that the system switches to runlevel 3, for example due to a command like "telinit 3" given by root. What will happen to the rc job? Obviously, the rc job will be started since it is currently stopped and the event runlevel 3 is matching the start events. But from now on, things are unclear to me: According to the manual $RUNLEVEL evaluates to the new runlevel when the job is started (that means 3 in our example). Therefore, the next stanza "stop on runlevel [!$RUNLEVEL]" translates to "stop on runlevel [!3]"; that means we have a first stanza which will trigger the job, but the second stanza will never stop the job and seems to be useless. Since I know that the Ubuntu / Upstart people won't do useless things, I must be heavily misunderstanding something. I would be grateful for any explanation. While trying to understand this, an additional question came to my mind. If I had contradicting start and stop triggers, for example start on foo stop on foo what would happen? I swear I never will do that, but I am nevertheless very interested in how Upstart handles that on the theoretical level. Thank you very much! Editing the question as a reaction on geekosaur's first answer: I can see the parallelism, but it is not that easy (at least, not to me). Let's assume the job aurrently is still running, and a new runlevel event comes in (of course, the new runlevel is different from the current one). Then, the following should happen: 1) The job is single instance. That means that "start on ..." won't be triggered since the job is currently running; $RUNLEVEL is not touched. 2) "stop on ..." will be triggered since the new runlevel is different from $RUNLEVEL, so the job will be aborted. 3) Now, the job is stopped and waiting. I can't see how it is restarted with the new runlevel. AFAIK, initctl emits events only once, so "start on ..." won't be triggered and the new runlevel won't be entered. I know that I still misunderstanding something, and I am grateful for explanations. Thank you very much!

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• What are some reasonable stylistic limits on type inference?

  - by Jon Purdy

  C++0x adds pretty darn comprehensive type inference support. I'm sorely tempted to use it everywhere possible to avoid undue repetition, but I'm wondering if removing explicit type information all over the place is such a good idea. Consider this rather contrived example: Foo.h: #include <set> class Foo { private: static std::set<Foo*> instances; public: Foo(); ~Foo(); // What does it return? Who cares! Just forward it! static decltype(instances.begin()) begin() { return instances.begin(); } static decltype(instances.end()) end() { return instances.end(); } }; Foo.cpp: #include <Foo.h> #include <Bar.h> // The type need only be specified in one location! // But I do have to open the header to find out what it actually is. decltype(Foo::instances) Foo::instances; Foo() { // What is the type of x? auto x = Bar::get_something(); // What does do_something() return? auto y = x.do_something(*this); // Well, it's convertible to bool somehow... if (!y) throw "a constant, old school"; instances.insert(this); } ~Foo() { instances.erase(this); } Would you say this is reasonable, or is it completely ridiculous? After all, especially if you're used to developing in a dynamic language, you don't really need to care all that much about the types of things, and can trust that the compiler will catch any egregious abuses of the type system. But for those of you that rely on editor support for method signatures, you're out of luck, so using this style in a library interface is probably really bad practice. I find that writing things with all possible types implicit actually makes my code a lot easier for me to follow, because it removes nearly all of the usual clutter of C++. Your mileage may, of course, vary, and that's what I'm interested in hearing about. What are the specific advantages and disadvantages to radical use of type inference?

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• How to force a clock update using ntp?

  - by ysap

  I am running Ubuntu on an ARM based embedded system that lacks a battery backed RTC. The wake-up time is somewhere during 1970. Thus, I use the NTP service to update the time to the current time. I added the following line to /etc/rc.local file: sudo ntpdate -s time.nist.gov However, after startup, it still takes a couple of minutes until the time is updated, during which period I cannot work effectively with tar and make. How can I force a clock update at any given time? UPDATE 1: The following (thanks to Eric and Stephan) works fine from command line, but fails to update the clock when put in /etc/rc.local: $ date ; sudo service ntp stop ; sudo ntpdate -s time.nist.gov ; sudo service ntp start ; date Thu Jan 1 00:00:58 UTC 1970 * Stopping NTP server ntpd [ OK ] * Starting NTP server [ OK ] Thu Feb 14 18:52:21 UTC 2013 What am I doing wrong? UPDATE 2: I tried following the few suggestions that came in response to the 1st update, but nothing seems to actually do the job as required. Here's what I tried: Replace the server to us.pool.ntp.org Use explicit paths to the programs Remove the ntp service altogether and leave just sudo ntpdate ... in rc.local Remove the sudo from the above command in rc.local Using the above, the machine still starts at 1970. However, when doing this from command line once logged in (via ssh), the clock gets updated as soon as I invoke ntpdate. Last thing I did was to remove that from rc.local and place a call to ntpdate in my .bashrc file. This does update the clock as expected, and I get the true current time once the command prompt is available. However, this means that if the machine is turned on and no user is logged in, then the time never gets updates. I can, of course, reinstall the ntp service so at least the clock is updated within a few minutes from startup, but then we're back at square 1. So, is there a reason why placing the ntpdate command in rc.local does not perform the required task, while doing so in .bashrc works fine?

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• System.Runtime.InteropServices.COMException (0x80070008): Not enough storage is available to process

  - by Darryl Braaten

  I am trying to diagnose this exception. "System.Runtime.InteropServices.COMException (0x80070008): Not enough storage is available to process this command. (Exception from HRESULT: 0x80070008) at System.Runtime.Remoting.RemotingServices.AllocateUninitializedObject(RuntimeType objectType) at System.Runtime.Remoting.RemotingServices.AllocateUninitializedObject(Type objectType) at System.Runtime.Remoting.Activation.ActivationServices.CreateInstance(Type serverType) at System.Runtime.Remoting.Activation.ActivationServices.IsCurrentContextOK(Type serverType, Object[] props, Boolean bNewObj) at Oracle.DataAccess.Client.CThreadPool..ctor() at Oracle.DataAccess.Client.OracleCommand.set_CommandTimeout(Int32 value) ... It does not look like any of the normal types of "storage" have hit any limits. The application is using about 400MB of memory, 70 threads, 2000 handles and the hard drive has many GB free. The machine is running Windows 2003 Enterprise server with 16GB of RAM so memory shouldn't be an issue. The application is running as a windows service so there are no GDI objects being used. Running out of GDI handles is a common cause of this exception. Database connections, commands & readers are all all wrapped with using blocks so they should be getting cleaned up correctly.

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• .NET 3.0 Unit Testing getting System.MethodAccessException calling .NET 2.0

  - by NealWalters

  Is there any way to get around this exception? Can I not call a .NET 2.0 from 3.5? I have to write .NET 2.0 to maintain capability with BizTalk 2006/R2. But I would like to test with VS2008 Unit Tests to be consistent to other non-BizTalk code that we are testing. Test method ABC.UnitTest.UnitTest1.TestReferenceCode1 threw exception: System.MethodAccessException: ABC.EasyRegEx.extractUsingRegEx(System.String, System.String).

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• how to create use case diagram from visual studio 2008 Team System

  - by monkey_boys

  how to create use case diagram from visual studio 2008 Team System same this

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• Cannot find System.Web.Script.Service namespace error after upgrading to Visual studio 2010

  - by Gavin

  I've just upgraded a VS 2008 project to VS 2010, converting the project but keeping the target as .NET 3.5 (SP1 is installed). My project worked without issue under VS 2008 on another machine. I've added references to System.Web.Extensions.dll but I'm still getting the following errors from code in the App_Code folder: 1) Cannot find System.Web.Script.Service namespace 2) Type 'System.Web.Script.Services.ScriptService' is not defined. 3) Type 'System.Runtime.Serialization.Json.DataContractJsonSerializer' is not defined. Anyone have any ideas what the problem might be as I'm pretty stumped? :(

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• IDataRecord.IsDBNull causes an System.OverflowException (Arithmetic Overflow)

  - by Ciddan

  Hi! I have a OdbcDataReader that gets data from a database and returns a set of records. The code that executes the query looks as follows: OdbcDataReader reader = command.ExecuteReader(); while (reader.Read()) { yield return reader.AsMovexProduct(); } The method returns an IEnumerable of a custom type (MovexProduct). The convertion from an IDataRecord to my custom type MovexProduct happens in an extension-method that looks like this (abbrev.): public static MovexProduct AsMovexProduct(this IDataRecord record) { var movexProduct = new MovexProduct { ItemNumber = record.GetString(0).Trim(), Name = record.GetString(1).Trim(), Category = record.GetString(2).Trim(), ItemType = record.GetString(3).Trim() }; if (!record.IsDBNull(4)) movexProduct.Status1 = int.Parse(record.GetString(4).Trim()); // Additional properties with IsDBNull checks follow here. return movexProduct; } As soon as I hit the if (!record.IsDBNull(4)) I get an OverflowException with the exception message "Arithmetic operation resulted in an overflow." StackTrace: System.OverflowException was unhandled by user code Message=Arithmetic operation resulted in an overflow. Source=System.Data StackTrace: at System.Data.Odbc.OdbcDataReader.GetSqlType(Int32 i) at System.Data.Odbc.OdbcDataReader.GetValue(Int32 i) at System.Data.Odbc.OdbcDataReader.IsDBNull(Int32 i) at JulaAil.DataService.Movex.Data.ExtensionMethods.AsMovexProduct(IDataRecord record) [...] I've never encountered this problem before and I cannot figure out why I get it. I have verified that the record exists and that it contains data and that the indexes I provide are correct. I should also mention that I get the same exception if I change the if-statemnt to this: if (record.GetString(4) != null). What does work is encapsulating the property-assignment in a try {} catch (NullReferenceException) {} block - but that can lead to performance-loss (can it not?). I am running the x64 version of Visual Studio and I'm using a 64-bit odbc driver. Has anyone else come across this? Any suggestions as to how I could solve / get around this issue? Many thanks!

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