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  • How to refactor to cleaner version of maintaing states of the widget

    - by George
    Backstory I inherited a bunch of code that I'd like to refactor. It is a UI application written in javascript. Current state: We have main application which consist of several UI components. And each component has entry fields, textboxes, menus, etc), like "ticket", "customer information", etc. Based on input, where the application was called from, who is the user, we enable/disable, hide, show, change titles. Unfortunately, the app grew to the point where it is really hard to scale, add new features. Main the driver (application code) calls set/unset functions of the respective components. So a lot of the stuff look like this Main app unit function1() { **call_function2()** component1.setX(true); component1.setY(true); component2.setX(false); } call_function2() { // it may repeat some of the code function1 called } and we have a lot of this in the main union. I am cleaning this mess. What is the best way to maintain the state of widgets? Please let me know if you need me to clarify.

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  • How can find out the device Id of my unmounted DVD?

    - by fred.bear
    When I put a DVD into the DVD drive, it appears in Nautilus Places, but is not automatically mounted. (this is by personal choice). In this unmounted state, mount (of course) reports nothing, and likewise for df.. but Nautilus is aware of the DVD hardware unit and has read the Label; which it shows in Places So it seems to me that Nautilus has already accessed the DVD devices (Did it temporarily mount it?)... The main point of my question was to determine how to find the device Id of an unmounted device .. but as I've been writing this, I now think it may not be as simple as that... This issue came up because I wanted to test this command cat iso-pieces.* | growisofs -Z /dev/dvd=/dev/stdin, but then realized that I didn't know how to get my DVD's device Id. ... and does the above command requires a mounted device, or does it write directly to the device? ... as you can see, I'm a bit vague about devices :) Come to think of it maybe Nautalus read the DVD device directly, because when all is said and done, something has to read/write directly to it. info growisofs says: Under Linux it will most likely be an ide-scsi device such as "/dev/scd0 How can I find this Id via a script?

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  • Translating an object along its heading

    - by Kuros
    I am working on a simulation that requires me to have several objects moving around in 3D space (text output of their current position on the grid and heading is fine, I do not need graphics), and I am having some trouble getting objects to move along their relative headings. I have a basic understanding of vectors and matrices. I am using a vector to represent their position, and I am also using Euler Angles. I can translate one of my entities with a matrix along whatever axis, and I can alter their heading. For example, if I have an entity at (order is XYZ) 1, 1, 1, with a heading of 0, I can apply a translation matrix to get them to talk to 1, 1, 2 fine. However, if I change their heading to 270, they still walk to 1, 1, 3, instead of 2, 1, 2 as I desire. I have a feeling that my problem lies in not translating my matrix from world space to object space, but I am not sure how to go about that. How can I do this? Addition: I am using 3D vectors to represent their current position and their heading (using the three euler angles). For now, all I want to do is have an entity walk in a square, reporting their current position at each step. So, assuming it starts at 10, 10, 10 I want it to walk as follows: 10,10,10 -> 10, 10, 15 10, 10, 15 -> 5, 10, 15 5, 10, 15 -> 5, 10, 10 5, 10, 10 -> 10, 10, 10 My 1 Z unit translation matrix is as follows: [1 0 0 0] [0 1 0 0] [0 0 1 1] [0 0 0 1] My rotation matrix is as follows: [0 0 1 0] [0 1 0 0] [-1 0 0 0] [0 0 0 1]

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  • How to rotate a group of objects around a common center?

    - by user1662292
    I've made a model in 3D Studio Max 9. It consists of a variety of cubes, clyinders etc. In XNA I've imported the model okay and it shows correctly. However, when I apply rotation, each component in the model rotates around it's own centre. I want the model to rotate as a single unit. I've linked the components in 3D Max and they rotate as I want in Max. protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); model = Content.Load<Model>("Models/Alien1"); } protected override void Update(GameTime gameTime) { camera.Update(1f, new Vector3(), graphics.GraphicsDevice.Viewport.AspectRatio); rotation += 0.1f; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); Matrix[] transforms = new Matrix[model.Bones.Count]; model.CopyAbsoluteBoneTransformsTo(transforms); Matrix worldMatrix = Matrix.Identity; Matrix rotationYMatrix = Matrix.CreateRotationY(rotation); Matrix translateMatrix = Matrix.CreateTranslation(location); worldMatrix = rotationYMatrix * translateMatrix; foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = worldMatrix * transforms[mesh.ParentBone.Index]; effect.View = camera.viewMatrix; effect.Projection = camera.projectionMatrix; effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; } mesh.Draw(); } base.Draw(gameTime); } More Info: Rotating the object via it's properties works fine so I'm guessing there's something up with the code rather than with the object itself. Translating the object also causes the objects to get moved independently of each other rather than as a single model and each piece becomes spread around the scene. The model is in .X format.

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  • Will I be able to get programming interviews at good software companies with a non-CS degree?

    - by friend
    I'll be graduating in a year, but I'll have a degree in Economics. I'm pretty much done with my Economics coursework, and by the time next year comes around I will have devoted 1.5 years to learning CS. I will have almost finished the requirements to graduate with a degree in CS, but unfortunately my school requires a science series that would add another 6-9 months of study if I were to try and get the degree (not to mention a max unit cap). I have or will have taken: Objected Oriented Programming Discrete Math Data structures Calculus through multivariable (doubt this matters at all) Linear Algebra (same) Computer Organization Operating Systems Computational Statistics (many data mining projects in R) Parallel Programming Programming Languages Databases Algorithms Compilers Artificial Intelligence I've done well in the ones I've taken, and I hope to do well in the rest, but will that matter if I can't say to the HR people that I have a CS degree? I'd be happy to get an internship at first too, so should I just apply as if I'm an intern and not looking for fulltime, and then try and parlay that into something? Sidenote if you have time -- Is a computer networks or theory of computation class important? Would it be worth taking either of those in lieu of a class on my list? edit -- I know this isn't AskReddit or College Confidential; I know there will be some outrage at posting a question like this. I'm merely looking for insight into a situation that I've been struggling with, and I think this is the absolute best place to find an answer to this question. Thanks.

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  • Reflection velocity

    - by MindSeeker
    I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't find a tutorial that tackles this problem and includes the nitty gritty math/code to verify what I'm doing). If it is right, is there a better/faster/more elegant way to do this? Note that the object (this) is the moving circle, and the EntPointer object is the immovable circle. //take vector separating the two centers <x, y>, and then get unit vector of the result: MathVector2d unitnormal = MathVector2d(this -> Retxpos() - EntPointer -> Retxpos(), this -> Retypos() - EntPointer -> Retypos()).UnitVector(); //take tangent <-y, x> of the unitnormal: MathVector2d unittangent = MathVector2d(-unitnormal.ycomp, unitnormal.xcomp); MathVector2d V1 = MathVector2d(this -> Retxvel(), this -> Retyvel()); //Calculate the normal and tangent vector lengths of the velocity: (the normal changes, the tangent stays the same) double LengthNormal = DotProduct(unitnormal, V1); double LengthTangent = DotProduct(unittangent, V1); MathVector2d VelVecNewNormal = unitnormal.ScalarMultiplication(-LengthNormal); //the negative of what it was before MathVector2d VelVecNewTangent = unittangent.ScalarMultiplication(LengthTangent); //this stays the same MathVector2d NewVel = VectorAddition(VelVecNewNormal, VelVecNewTangent); //combine them xvel = NewVel.xcomp; //and then apply them yvel = NewVel.ycomp; Note also that this question is just about velocity, the position code is handled elsewhere (in other words, assume that this code is implemented at the exact moment that the circles begin to overlap). Thanks in advance for your help and time!

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  • Spending a good fortune on a certificate holding Scrum Master or a Veteran XP coach?

    - by ashy_32bit
    There is a very prestigious company that delivers a well-sold software about financial systems. It has more that 20 years of history, and is staffed with about 20 programmers and much larger number of managerial staff. Dissatisfied customers have reported strange bugs and no one has a clue what is wrong, hard to read code, and customization is prohibitively expensive. In a word, the software is rotten. The company decided to spend a fortune and found the Agile thing as the remedy but they are stuck about what it is they need most urgently. Is it about the process or the developers or both? The challenge breaks down to the following options: They can hire a certificate holding Scrum Master to teach them Scrum. When asked about the value of doing it, the SM responded: "I will prepare them to embrace Agile and only then they can go Agile and save the product". They can as well hire a veteran XP coach. When posed with the same question he responded : "The most urgent problem is with the programmers and not the management, XP will save the product from rot and only then Scrum will make sense" Developers are far from capable of doing agile programming practices at the moment. No unit tests, no pair programmings, no CI (huh? what is it?) ... you get the idea. Some say they would be far better trying to improve their programming first (hire option 2) and then go with the process. Many say quite the opposite. Any insights ?

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  • Information I need to know as a Java Developer [on hold]

    - by Woy
    I'm a java developer. I'm trying to get more knowledge to become a better programmer. I've listed a number of technologies to learn. Instead of what I've listed, what technologies would you suggest to learn as well for a Junior Java Developer? I realize, there's a lot of things to study. Java: - how a garbage collector works - resource management - network programming - TCP/IP HTTP - transactions, - consistency: interfaces, classes collections, hash codes, algorithms, comp. complexity concurrent programming: synchronizing, semafores steam management metability: thread-safety byte code manipulations, reflections, Aspect-Oriented Programming as base to understand frameworks such as Spring etc. Web stack: servlets, filters, socket programming Libraries: JDK, GWT, Apache Commons, Joda-Time, Dependency Injections: Spring, Nano Tools: IDE: very good knowledge - debugger - profiler - web analyzers: Wireshark, firebugs - unit testing SQL/Databases: Basics SELECTing columns from a table Aggregates Part 1: COUNT, SUM, MAX/MIN Aggregates Part 2: DISTINCT, GROUP BY, HAVING + Intermediate JOINs, ANSI-89 and ANSI-92 syntax + UNION vs UNION ALL x NULL handling: COALESCE & Native NULL handling Subqueries: IN, EXISTS, and inline views Subqueries: Correlated ITH syntax: Subquery Factoring/CTE Views Advanced Topics Functions, Stored Procedures, Packages Pivoting data: CASE & PIVOT syntax Hierarchical Queries Cursors: Implicit and Explicit Triggers Dynamic SQL Materialized Views Query Optimization: Indexes Query Optimization: Explain Plans Query Optimization: Profiling Data Modelling: Normal Forms, 1 through 3 Data Modelling: Primary & Foreign Keys Data Modelling: Table Constraints Data Modelling: Link/Corrollary Tables Full Text Searching XML Isolation Levels Entity Relationship Diagrams (ERDs), Logical and Physical Transactions: COMMIT, ROLLBACK, Error Handling

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  • Enabling GTX 570

    - by Silas
    Hello i just built up my new system: Asus Rock Z77 Extreme 4 Intel i7 3770k 16 Gb Corsair Ram Zotac Nvidia GTX 570 bequiet! 630W Power supply 120 GB SSD So after i installed UBUNTU 12.04 64 bit. It ran smoothly. I downloaded and installed all the recommended updates. After checking the Sytem details the GTX 570 didnt show up as graphics unit. so i figured i needed to download the drivers. So i did but being a complete newbie to linux i didnt succeed in installing them. (I think) Anyway after several tries and errors i shut down the PC and restarted it. Resultung in do Signal to my screen after trying to reboot and all the monitor outs with no result i took out the graphic card and now it boots normally but after booting it says there is a problem with the system the graphics cant be recognized something something. So Question A: What do i do? I Like linux but the arbitrarity of the Errors that occur without any changes to the system scare me. Question B: Is there A beginners guide to Ubuntu where i could start from scratch because i really want this to work? Question C: Now that the System is (suddently) showing these graphic errors So far without visible consequence despite the error message. should i reinstall the GPU and give the driver installation another try or the other way around? Ill be very grateful for any help. Thank you in advance!

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  • Guidelines for creating referentially transparent callables

    - by max
    In some cases, I want to use referentially transparent callables while coding in Python. My goals are to help with handling concurrency, memoization, unit testing, and verification of code correctness. I want to write down clear rules for myself and other developers to follow that would ensure referential transparency. I don't mind that Python won't enforce any rules - we trust ourselves to follow them. Note that we never modify functions or methods in place (i.e., by hacking into the bytecode). Would the following make sense? A callable object c of class C will be referentially transparent if: Whenever the returned value of c(...) depends on any instance attributes, global variables, or disk files, such attributes, variables, and files must not change for the duration of the program execution; the only exception is that instance attributes may be changed during instance initialization. When c(...) is executed, no modifications to the program state occur that may affect the behavior of any object accessed through its "public interface" (as defined by us). If we don't put any restrictions on what "public interface" includes, then rule #2 becomes: When c(...) is executed, no objects are modified that are visible outside the scope of c.__call__. Note: I unsuccessfully tried to ask this question on SO, but I'm hoping it's more appropriate to this site.

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  • How to educate business managers on the complexity of adding new features? [duplicate]

    - by Derrick Miller
    This question already has an answer here: How to educate business managers on the complexity of adding new features? [duplicate] 3 answers We maintain a web application for a client who demands that new features be added at a breakneck pace. We've done our best to keep up with their demands, and as a result the code base has grown exponentially. There are now so many modules, subsystems, controllers, class libraries, unit tests, APIs, etc. that it's starting to take more time to work through all of the complexity each time we add a new feature. We've also had to pull additional people in on the project to take over things like QA and staging, so the lead developers can focus on developing. Unfortunately, the client is becoming angry that the cost for each new feature is going up. They seem to expect that we can add new features ad infinitum and the cost of each feature will remain linear. I have repeatedly tried to explain to them that it doesn't work that way - that the code base expands in a fractal manner as all these features are added. I've explained that the best way to keep the cost down is to be judicious about which new features are really needed. But, they either don't understand, or they think I'm bullshitting them. They just sort of roll their eyes and get angry. They're all completely non-technical, and have no idea what does into writing software. Is there a way that I can explain this using business language, that might help them understand better? Are there any visualizations out there, that illustrate the growth of a code base over time? Any other suggestions on dealing with this client?

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  • Is there a better strategy than relying on the compiler to catch errors?

    - by koan
    I've been programming in C and C++ for some time, although I would say I'm far from being an expert. For some time, I've been using various strategies to develop my code such as unit tests, test driven design, code reviews and so on. When I wrote my first programs in BASIC, I typed in long blocks before finding they would not run and they were a nightmare to debug. So I learned to write a small bit and then test it. These days, I often find myself repeatedly writing a small bit of code then using the compiler to find all the mistakes. That's OK if it picks up a typo but when you start adjusting the parameters types etc just to make it compile you can screw up the design. It also seems that the compiler is creeping into the design process when it should only be used for checking syntax. There's a danger here of over reliance on the compiler to make my programs better. Are there better strategies than this? I vaguely remember some time ago an article on a company developing a type of C compiler where an extra header file also specified the prototypes. The idea was that inconsistencies in the API definition would be easier to catch if you had to define it twice in different ways.

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  • MVVM and service pattern

    - by alfa-alfa
    I'm building a WPF application using the MVVM pattern. Right now, my viewmodels calls the service layer to retrieve models (how is not relevant to the viewmodel) and convert them to viewmodels. I'm using constructor injection to pass the service required to the viewmodel. It's easily testable and works well for viewmodels with few dependencies, but as soon as I try to create viewModels for complex models, I have a constructor with a LOT of services injected in it (one to retrieve each dependencies and a list of all available values to bind to an itemsSource for example). I'm wondering how to handle multiple services like that and still have a viewmodel that I can unit test easily. I'm thinking of a few solutions: Creating a services singleton (IServices) containing all the available services as interfaces. Example: Services.Current.XXXService.Retrieve(), Services.Current.YYYService.Retrieve(). That way, I don't have a huge constructor with a ton of services parameters in them. Creating a facade for the services used by the viewModel and passing this object in the ctor of my viewmodel. But then, I'll have to create a facade for each of my complexe viewmodels, and it might be a bit much... What do you think is the "right" way to implement this kind of architecture ?

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  • OpenGL: Move camera regardless of rotation

    - by Markus
    For a 2D board game I'd like to move and rotate an orthogonal camera in coordinates given in a reference system (window space), but simply can't get it to work. The idea is that the user can drag the camera over a surface, rotate and scale it. Rotation and scaling should always be around the center of the current viewport. The camera is set up as: gl.glMatrixMode(GL2.GL_PROJECTION); gl.glLoadIdentity(); gl.glOrtho(-width/2, width/2, -height/2, height/2, nearPlane, farPlane); where width and height are equal to the viewport's width and height, so that 1 unit is one pixel when no zoom is applied. Since these transformations usually mean (scaling and) translating the world, then rotating it, the implementation is: gl.glMatrixMode(GL2.GL_MODELVIEW); gl.glLoadIdentity(); gl.glRotatef(rotation, 0, 0, 1); // e.g. 45° gl.glTranslatef(x, y, 0); // e.g. +10 for 10px right, -2 for 2px down gl.glScalef(zoomFactor, zoomFactor, zoomFactor); // e.g. scale by 1.5 That however has the nasty side effect that translations are transformed as well, that is applied in world coordinates. If I rotate around 90° and translate again, X and Y axis are swapped. If I reorder the transformations so they read gl.glTranslatef(x, y, 0); gl.glScalef(zoomFactor, zoomFactor, zoomFactor); gl.glRotatef(rotation, 0, 0, 1); the translation will be applied correctly (in reference space, so translation along x always visually moves the camera sideways) but rotation and scaling are now performed around origin. It shouldn't be too hard, so what is it I'm missing?

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  • Is spreading code with refactoring comments a good idea?

    - by Uooo
    I am working on a "spaghetti-code" project, and while I am fixing bugs and implementing new features, I also do some refactoring in order to make the code unit-testable. The code is often so tightly coupled or complicated that fixing a small bug would result in a lot of classes being rewritten. So I decided to draw a line somewhere in the code where I stop refactoring. To make this clear, I drop some comments in the code explaining the situation, like: class RefactoredClass { private SingletonClass xyz; // I know SingletonClass is a Singleton, so I would not need to pass it here. // However, I would like to get rid of it in the future, so it is passed as a // parameter here to make this change easier later. public RefactoredClass(SingletonClass xyz) { this.xyz = xyz; } } Or, another piece of cake: // This might be a good candidate to be refactored. The structure is like: // Version String // | // +--> ... // | // +--> ... // | // ... and so on ... // Map map = new HashMap<String, Map<String, Map<String, List<String>>>>(); Is this a good idea? What should I keep in mind when doing so?

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  • How should I structure the implementation of turn-based board game rules?

    - by Setzer22
    I'm trying to create a turn-based strategy game on a tilemap. I'm using design by component so far, but I can't find a nice way to fit components into the part I want to ask. I'm struggling with the "game rules" logic. That is, the code that displays the menu, allows the player to select units, and command them, then tells the unit game objects what to do given the player input. The best way I could thing of handling this was using a big state machine, so everything that could be done in a "turn" is handled by this state machine, and the update code of this state machine does different things depending on the state. However, this approach leads to a large amount of code (anything not model-related) going into a big class. Of course I can subdivide this big class into more classes, but it doesn't feel modular and upgradable enough. I'd like to know of better systems to handle this in order to be able to upgrade the game with new rules without having a monstruous if/else chain (or switch / case, for that matter). Any ideas? What specific design pattern other than MVC should I be using?

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  • moving in the wrong direction

    - by Will
    Solution: To move a unit forward: forward = Quaternion(0,0,0,1) rotation.normalize() # ocassionally ... pos += ((rotation * forward) * rotation.conjugated()).xyz().normalized() * speed I think the trouble stemmed from how the Euclid math library was doing Quaternion*Vector3 multiplication, although I can't see it. I have a vec3 position, a quaternion for rotation and a speed. I compute the player position like this: rot *= Quaternion().rotate_euler(0.,roll_speed,pitch_speed) rot.normalize() pos += rot.conjugated() * Vector3(0.,0.,-speed) However, printing the pos to console, I can see that I only ever seem to travel on the x-axis. When I draw the scene using the rot quaternion to rotate my camera, it shows a proper orientation. What am I doing wrong? Here's an example: You start off with rotation being an identity quaternion: w=1,x=0,y=0,z=0 You move forward; the code correctly decrements the Z You then pitch right over to face the other way; if you spin only 175deg it'll go in right direction; you have to spin past 180deg. It doesn't matter which direction you spin in, up or down, though Your quaternion can then be something like: w=0.1,x=0.1,y=0,z=0 And moving forward, you actually move backward?! (I am using the euclid Python module, but its the same as every other conjulate) The code can be tried online at http://williame.github.com/ludum_dare_24_evolution/ The only key that adjusts the speed is W and S. The arrow keys only adjust the pitch/roll. At first you can fly ok, but after a bit of weaving around you end up getting sucked towards one of the sides. The code is https://github.com/williame/ludum_dare_24_evolution/blob/cbacf61a7159d2c83a2187af5f2015b2dde28687/tiny1web.py#L102

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  • CI - How long is continous?

    - by Andy
    We currently are using CCNet as our continous integration server. Most projects check for changes every 30 seconds (the default) and if needed perform a build (unit tests, stylecop, fxcop, etc). We've gotten quite a few projects now, and the server spends most of its time near 100% cpu utilization. This has alarmed some of the development team, even though the server is responsive and builds are still about the same length of time they've always been. Its been suggested that we lower the check interval to about five minutes. To me that seems too long, and we risk people committing code and then going home for the weekend and now there's a broken build possibly holding up others. In response, the suggestion is that if someone needs to know the results they can force the build. But that seems to defeat the purpose of CI, as I thought it was supposed to be automated. My proposed solution is just to get another build server and split the builds amongst the servers. Am I thinking about this the wrong way, or is there a point where if integration isn't often enough you're not really doing CI anymore?

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  • Oracle regains the #1 UNIX Shipments Marketshare

    - by EricReid-Oracle
    Oracle has regained the #1 UNIX Server Shipments spot! According to IDC, Oracle’s share was 33.6%, up from 32.7% in the year ago period, and 32.2% in C4Q13:  IDC: WW Unix Unit Shipments, Share, Growth 2013Q1 Share 2013Q4 Share 2014Q1 Share Sequential Growth Y/Y Growth Oracle 10,141 32.7% 10,294 32.2% 8,355 33.6% -18.8% -17.6% IBM 10,203 32.9% 11,533 36.0% 6,919 27.8% -40.0% -32.2% HP 7,046 22.7% 6,786 21.2% 6,549 26.4% -3.5% -7.1% Fujitsu 1,174 3.8% 1,141 3.6% 1,069 4.3% -6.3% -8.9% Dell 565 1.8% 499 1.6% 519 2.1% 4.0% -8.2% NEC 69 0.2% 81 0.3% 63 0.3% -22.5% -9.4% Others 1,804 5.8% 1,684 5.3% 1,380 5.6% -18.1% -23.5% Total Market 31,002 100.0% 32,018 100.0% 24,854 100.0% -22.4% -19.8% While the UNIX server space is currently undergoing some contraction (on a pure numbers basis), this can be traced in part to an overall consolidation trend, due to the greatly-increased price-performance of our systems. Consider this: one SPARC T5-4 system has 1/16th the number of sockets and 1/192nd the number of cores of the previous high-end M9000-64 system -- all at 5X the price-performance. SPARC. Solaris. Nuff' said.

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  • Reliance on the compiler

    - by koan
    I've been programming in C and C++ for some time, although I would say I'm far from being expert. For some time I've been using various strategies to develop my code such as unit tests, test driven design, code reviews and so on. When I wrote my first programs in BASIC I typed in long listings before finding they would not run and they were a nightmare to debug. So I learnt to write a small bit and then test it. These days I often find myself repeatedly writing a small bit of code then using the compiler to find all the mistakes. That's OK if it picks up a typo but when you start adjusting the parameters types etc just to make it compile you can screw up the design. It also seems that the compiler is creeping into the design process when it should only be used for checking syntax. There's a danger here of over reliance on the compiler to make my programs better. Are there better strategies than this ? I vaguely remember some time ago an article on a company developing a type of C compiler where an extra header file also specified the prototypes. The idea was that inconsistencies in the API definition would be easier to catch if you had to define it twice in different ways.

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  • What are the pitfalls of hardlinked files on my desktop PC?

    - by MountainX
    All the identical-content files on my PC are now hardlinked. (My data is completely de-duplicated. It is a consequence of the way I copied my data from my old computer.) What pitfalls do I need to be aware of now that certain actions on one file could silently affect a number of other files? I know that deleting the file I'm working on is not a problem (assuming I deleted it on purpose). It doesn't affect any of the other hardlinked files and I don't see that the delete action would lead to unexpected side effects. Moving or renaming the file is not a problem. I don't see any unexpected consequences. I don't think copying hardlinked files is a problem, but I'm not as confident about any unexpected consequences in this regard. What I have seen is that making a copy (to the same disk) of a hardlinked file with cp keeps the copy hardlinked (i.e., inode number doesn't change in the copy). Copying to another filesystem obviously breaks the hardlink. (I guess one pitfall is forgetting this fact, given that my PC has 3 hard disks.) Changing permissions does affect all linked files. So far this has proven handy. (I made a large number of the hardlinked files read-only.) None of the operations above seem to produce any major unexpected consequences. However, as was pointed out to me by Daniel Beck in a comment, editing or modifying a file can sometimes be a problem. It depends on the tool and maybe the type of edit. (For example, editing small text files using sed seems to always break the link while using nano doesn't.) This introduces the chance that editing one file could affect all the hardlinked files (i.e., alter the original inode). My proposed solution to this is to make all hardlinked files read-only (and that is already mostly the case). If I can't do that for some files, I will unlink those particular files. Is there any problem with this read-only approach? I'm assuming that if I go to edit a file and find it to be read-only, I'll remember to unlink that filename while making it writable. So one pitfall might be forgetting this rule. In that case, I'll have to rely on my backups. Am I correct in the above statements? And what else do I need to know? BTW, I'm running Kubuntu 12.04. I'm also using btrfs. (I have 2 SSD's and 1 HDD in the PC. I will also be adding an external USB HDD. I'm also connected to a network and I mount some NFS shares. I don't assume any of these last bits are relevant to the question, but I'm adding them just in case.) BTW, since I have more than one drive (with separate file systems), to unlink any file all I have to do is copy it to another drive, then move it back. However, using sed also works (in my testing). Here's my script: sed -i 's/\(.\)/\1/' file1 Surprisingly, this even unlinks zero byte files. In my testing it also appears to work on non-text files without any special options. (But I understand that the --binary option might be needed on Windows, MS-DOS and Cygwin.) However, copying to another disk and moving back may be the best way to unlink. For my use-case, unlink command doesn't really "unlink", rather it "removes".

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  • windows 2003 server : can't join domain

    - by phill
    I originally tried to rejoin a computer to a network which led to a "cannot find domain" error. The username/password box don't even come up. some tests i ran: I can ping the server, however I can't ping the domain name domain1.local. nslookup can't find the domain either. It looks to the isp's dns instead of my own to resolve the local machines. So i go to the dns and run netdiag.exe and gives me this error. DNS test . . . . . . . . . . . . . : Failed [WARNING] Cannot find a primary authoritative DNS server for the name 'stmartinsrv.stmartin.local.'. [RCODE_SERVER_FAILURE] The name 'srv.domain1.local.' may not be registered in DNS. [WARNING] The DNS entries for this DC are not registered correctly on DNS se rver '68.94.156.1'. Please wait for 30 minutes for DNS server replication. [WARNING] The DNS entries for this DC are not registered correctly on DNS se rver '68.94.157.1'. Please wait for 30 minutes for DNS server replication. [FATAL] No DNS servers have the DNS records for this DC registered. Redir and Browser test . . . . . . : Passed List of NetBt transports currently bound to the Redir NetBT_Tcpip_{04BB0F6B-06AE-4D60-80C8-2A7A24C1D87B} The redir is bound to 1 NetBt transport. List of NetBt transports currently bound to the browser NetBT_Tcpip_{04BB0F6B-06AE-4D60-80C8-2A7A24C1D87B} The browser is bound to 1 NetBt transport. then running dcdiag C:\Program Files\Support Toolsdcdiag Domain Controller Diagnosis Performing initial setup: Done gathering initial info. Doing initial required tests Testing server: Default-First-Site-Name\SRV Starting test: Connectivity The host 1c99f63c-49ec-40db-b3d3-6265c00fbd3e._msdcs.domain1.local cou ld not be resolved to an IP address. Check the DNS server, DHCP, server name, etc Although the Guid DNS name (1c99f63c-49ec-40db-b3d3-6265c00fbd3e._msdcs.domain1.local) couldn't be resolved, the server name (srv.domain1.local) resolved to the IP address (192.168.1.21) and was pingable. Check that the IP address is registered correctly with the DNS server. ......................... SRV failed test Connectivity Doing primary tests Testing server: Default-First-Site-Name\SRV Skipping all tests, because server SRV is not responding to directory service requests Running partition tests on : ForestDnsZones Starting test: CrossRefValidation ......................... ForestDnsZones passed test CrossRefValidation Starting test: CheckSDRefDom ......................... ForestDnsZones passed test CheckSDRefDom Running partition tests on : DomainDnsZones Starting test: CrossRefValidation ......................... DomainDnsZones passed test CrossRefValidation Starting test: CheckSDRefDom ......................... DomainDnsZones passed test CheckSDRefDom Running partition tests on : Schema Starting test: CrossRefValidation ......................... Schema passed test CrossRefValidation Starting test: CheckSDRefDom ......................... Schema passed test CheckSDRefDom Running partition tests on : Configuration Starting test: CrossRefValidation ......................... Configuration passed test CrossRefValidation Starting test: CheckSDRefDom ......................... Configuration passed test CheckSDRefDom Running partition tests on : domain1 Starting test: CrossRefValidation ......................... domain1 passed test CrossRefValidation Starting test: CheckSDRefDom ......................... domain1 passed test CheckSDRefDom Running enterprise tests on : domain1.local Starting test: Intersite ......................... domain1.local passed test Intersite Starting test: FsmoCheck ......................... domain1.local passed test FsmoCheck from previous postings, I've tried adding the domain suffix to the nic ip properties to both the client machine and the dc server which didn't help. note: there is only one nic on the server any ideas? thanks in advance

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  • Openswan ipsec transport tunnel not going up

    - by gparent
    On ClusterA and B I have installed the "openswan" package on Debian Squeeze. ClusterA ip is 172.16.0.107, B is 172.16.0.108 When they ping one another, it does not reach the destination. /etc/ipsec.conf: version 2.0 # conforms to second version of ipsec.conf specification config setup protostack=netkey oe=off conn L2TP-PSK-CLUSTER type=transport left=172.16.0.107 right=172.16.0.108 auto=start ike=aes128-sha1-modp2048 authby=secret compress=yes /etc/ipsec.secrets: 172.16.0.107 172.16.0.108 : PSK "L2TPKEY" 172.16.0.108 172.16.0.107 : PSK "L2TPKEY" Here is the result of ipsec verify on both machines: root@cluster2:~# ipsec verify Checking your system to see if IPsec got installed and started correctly: Version check and ipsec on-path [OK] Linux Openswan U2.6.28/K2.6.32-5-amd64 (netkey) Checking for IPsec support in kernel [OK] NETKEY detected, testing for disabled ICMP send_redirects [OK] NETKEY detected, testing for disabled ICMP accept_redirects [OK] Checking that pluto is running [OK] Pluto listening for IKE on udp 500 [OK] Pluto listening for NAT-T on udp 4500 [FAILED] Checking for 'ip' command [OK] Checking for 'iptables' command [OK] Opportunistic Encryption Support [DISABLED] root@cluster2:~# This is the end of the output of ipsec auto --status: 000 "cluster": 172.16.0.108<172.16.0.108>[+S=C]...172.16.0.107<172.16.0.107>[+S=C]; prospective erouted; eroute owner: #0 000 "cluster": myip=unset; hisip=unset; 000 "cluster": ike_life: 3600s; ipsec_life: 28800s; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 0 000 "cluster": policy: PSK+ENCRYPT+COMPRESS+PFS+UP+IKEv2ALLOW+lKOD+rKOD; prio: 32,32; interface: eth0; 000 "cluster": newest ISAKMP SA: #1; newest IPsec SA: #0; 000 "cluster": IKE algorithm newest: AES_CBC_128-SHA1-MODP2048 000 000 #3: "cluster":500 STATE_QUICK_R0 (expecting QI1); EVENT_CRYPTO_FAILED in 298s; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate 000 #2: "cluster":500 STATE_QUICK_I1 (sent QI1, expecting QR1); EVENT_RETRANSMIT in 13s; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate 000 #1: "cluster":500 STATE_MAIN_I4 (ISAKMP SA established); EVENT_SA_REPLACE in 2991s; newest ISAKMP; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate 000 Interestingly enough, if I do ike-scan on the server here's what happens: Doesn't seem to take my ike settings into account root@cluster1:~# ike-scan -M 172.16.0.108 Starting ike-scan 1.9 with 1 hosts (http://www.nta-monitor.com/tools/ike-scan/) 172.16.0.108 Main Mode Handshake returned HDR=(CKY-R=641bffa66ba717b6) SA=(Enc=3DES Hash=SHA1 Auth=PSK Group=2:modp1024 LifeType=Seconds LifeDuration(4)=0x00007080) VID=4f45517b4f7f6e657a7b4351 VID=afcad71368a1f1c96b8696fc77570100 (Dead Peer Detection v1.0) Ending ike-scan 1.9: 1 hosts scanned in 0.008 seconds (118.19 hosts/sec). 1 returned handshake; 0 returned notify root@cluster1:~# I can't tell what's going on here, this is pretty much the simplest config I can have according to the examples.

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  • How could I stop ssh offering a wrong key?

    - by Alvaro Maceda
    (This is a problem with ssh, not gitolite) I've configured gitolite on my home server (ubuntu 12.04 server, open-ssh). I want an special identityfile to administer the repositories, so I need to access throught ssh to my own host ussing two different identity keys. This is the content of my .ssh/config file: Host gitadmin.gammu.com User git IdentityFile /home/alvaro/.ssh/id_gitolite_mantra Host git.gammu.com User git IdentityFile /home/alvaro/.ssh/id_alvaro_mantra This is the content of my hosts file: # Git 127.0.0.1 gitadmin.gammu.com 127.0.0.1 git.gammu.com So I should be able to communicate with gitolite this way to access with the "normal" account: $ssh git.gammu.com and this way to access with the administrative account: $ssh gitadmin.gammu.com When I try to access with the normal account, all is ok: alvaro@mantra:~/.ssh$ ssh git.gammu.com PTY allocation request failed on channel 0 hello alvaro, this is gitolite 2.2-1 (Debian) running on git 1.7.9.5 the gitolite config gives you the following access: @R_ @W_ testing Connection to git.gammu.com closed. When I do the same with the administrative account: alvaro@mantra:~$ ssh gitadmin.gammu.com PTY allocation request failed on channel 0 hello alvaro, this is gitolite 2.2-1 (Debian) running on git 1.7.9.5 the gitolite config gives you the following access: @R_ @W_ testing Connection to gitadmin.gammu.com closed. It should show the administrative repository. If I launch ssh with verbose option: ssh -vvv gitadmin.gammu.com ... debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/alvaro/.ssh/id_alvaro_mantra (0x7f7cb6c0fbc0) debug2: key: /home/alvaro/.ssh/id_gitolite_mantra (0x7f7cb6c044d0) debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/alvaro/.ssh/id_alvaro_mantra debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg ssh-rsa blen 279 ... It's offering the key id_alvaro_mantra, and it should'nt!! The same happens when I specify the key with the -i option: ssh -i /home/alvaro/.ssh/id_gitolite_mantra -vvv gitadmin.gammu.com ... debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/alvaro/.ssh/id_alvaro_mantra (0x7fa365237f90) debug2: key: /home/alvaro/.ssh/id_gitolite_mantra (0x7fa365230550) debug2: key: /home/alvaro/.ssh/id_gitolite_mantra (0x7fa365231050) debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/alvaro/.ssh/id_alvaro_mantra debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg ssh-rsa blen 279 debug2: input_userauth_pk_ok: fp 36:b1:43:36:af:4f:00:e5:e1:39:50:7e:07:80:14:26 debug3: sign_and_send_pubkey: RSA 36:b1:43:36:af:4f:00:e5:e1:39:50:7e:07:80:14:26 debug1: Authentication succeeded (publickey). ... What the hell is happening??? I'm missing something, but I can't find what. These are the contents of my home dir: -rw-rw-r-- 1 alvaro alvaro 395 nov 14 18:00 authorized_keys -rw-rw-r-- 1 alvaro alvaro 326 nov 21 10:21 config -rw------- 1 alvaro alvaro 137 nov 20 20:26 environment -rw------- 1 alvaro alvaro 1766 nov 20 21:41 id_alvaromaceda.es -rw-r--r-- 1 alvaro alvaro 404 nov 20 21:41 id_alvaromaceda.es.pub -rw------- 1 alvaro alvaro 1766 nov 14 17:59 id_alvaro_mantra -rw-r--r-- 1 alvaro alvaro 395 nov 14 17:59 id_alvaro_mantra.pub -rw------- 1 alvaro alvaro 771 nov 14 18:03 id_developer_mantra -rw------- 1 alvaro alvaro 1679 nov 20 12:37 id_dos_pruebasgit -rw-r--r-- 1 alvaro alvaro 395 nov 20 12:37 id_dos_pruebasgit.pub -rw------- 1 alvaro alvaro 1679 nov 20 12:46 id_gitolite_mantra -rw-r--r-- 1 alvaro alvaro 397 nov 20 12:46 id_gitolite_mantra.pub -rw------- 1 alvaro alvaro 1675 nov 20 21:44 id_gitpruebas.es -rw-r--r-- 1 alvaro alvaro 408 nov 20 21:44 id_gitpruebas.es.pub -rw------- 1 alvaro alvaro 1679 nov 20 12:34 id_uno_pruebasgit -rw-r--r-- 1 alvaro alvaro 395 nov 20 12:34 id_uno_pruebasgit.pub -rw-r--r-- 1 alvaro alvaro 2434 nov 21 10:11 known_hosts There are a bunch of other keys which aren't offered... why id_alvaro_mantra is offered and not the other keys? I can't understand. I need some help, don't know where to look....

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  • Does this prove a network bandwidth bottleneck?

    - by Yuji Tomita
    I've incorrectly assumed that my internal AB testing means my server can handle 1k concurrency @3k hits per second. My theory at at the moment is that the network is the bottleneck. The server can't send enough data fast enough. External testing from blitz.io at 1k concurrency shows my hits/s capping off at 180, with pages taking longer and longer to respond as the server is only able to return 180 per second. I've served a blank file from nginx and benched it: it scales 1:1 with concurrency. Now to rule out IO / memcached bottlenecks (nginx normally pulls from memcached), I serve up a static version of the cached page from the filesystem. The results are very similar to my original test; I'm capped at around 180 RPS. Splitting the HTML page in half gives me double the RPS, so it's definitely limited by the size of the page. If I internally ApacheBench from the local server, I get consistent results of around 4k RPS on both the Full Page and the Half Page, at high transfer rates. Transfer rate: 62586.14 [Kbytes/sec] received If I AB from an external server, I get around 180RPS - same as the blitz.io results. How do I know it's not intentional throttling? If I benchmark from multiple external servers, all results become poor which leads me to believe the problem is in MY servers outbound traffic, not a download speed issue with my benchmarking servers / blitz.io. So I'm back to my conclusion that my server can't send data fast enough. Am I right? Are there other ways to interpret this data? Is the solution/optimization to set up multiple servers + load balancing that can each serve 180 hits per second? I'm quite new to server optimization, so I'd appreciate any confirmation interpreting this data. Outbound traffic Here's more information about the outbound bandwidth: The network graph shows a maximum output of 16 Mb/s: 16 megabits per second. Doesn't sound like much at all. Due to a suggestion about throttling, I looked into this and found that linode has a 50mbps cap (which I'm not even close to hitting, apparently). I had it raised to 100mbps. Since linode caps my traffic, and I'm not even hitting it, does this mean that my server should indeed be capable of outputting up to 100mbps but is limited by some other internal bottleneck? I just don't understand how networks at this large of a scale work; can they literally send data as fast as they can read from the HDD? Is the network pipe that big? In conclusion 1: Based on the above, I'm thinking I can definitely raise my 180RPS by adding an nginx load balancer on top of a multi nginx server setup at exactly 180RPS per server behind the LB. 2: If linode has a 50/100mbit limit that I'm not hitting at all, there must be something I can do to hit that limit with my single server setup. If I can read / transmit data fast enough locally, and linode even bothers to have a 50mbit/100mbit cap, there must be an internal bottleneck that's not allowing me to hit those caps that I'm not sure how to detect. Correct? I realize the question is huge and vague now, but I'm not sure how to condense it. Any input is appreciated on any conclusion I've made.

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