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• How to debug a fatal system crash - [graphical loop DOTA2]?

  - by Huw

  Whilst playing DOTA2, I occasionally and apparently randomly seem to be experiencing a fatal crash where the display freezes fixed and the audio loops over approx the last .5 of a second. Now, I'm interested in resolving this - but my trouble is I don't know where to start. The error appears non-reproducible (I've tried returning to games and deploying the same combination of events in hopes of pinning to to a certain shader etc), and I don't know which part of 'the stack' it might be coming from. Variables that occur to me: I custom build this system, did I do something wrong - is my PSU not providing enough power to the graphics card? I am running Steam and DOTA under Linux, could this new software have a bug Might it be something to do with my ATI Catalyst graphics drivers Is some other background process interfering I'm usually mid game when this occurs, so i quickly kill the power and reboot (when i'm lucky i can get back in with only 1-2 mins lost!). So my question here relates to logs. Where should I start to look or how might I set up logs to help me pin down a fatal crash of this kind by recording moments up to / before a crash and is this likely to be something I should push Steam to do, or is there something at a system level? Then perhaps I can return with a more specific question and perhaps even a bug report :) Many thanks in advance.

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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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• How to boot from toshiba recovery partition after installing ubuntu 14.04.1? [duplicate]

  - by Hunter Dotson

  This question already has an answer here: How to remove Ubuntu and put Windows back on? 14 answers Im new here and have not found a post even close to this so here it is: i installed ubuntu 14.04.1 over my Windows 7 Home Premium installation. didn't loose any important data.skip to when the install is done i tried out ubuntu and got sick of it after a while.(the try ubuntu option was greyed out) i got sick of ubuntu after about an hour and i tried to boot into my recovery partition. That's where im running into trouble: you are supposed to hold down the numerical "0" while turning on the power. but it just proceeds to load grub/ubuntu and does not even try to boot into the recovery partition. "000000000000" is all i get from holding it down I know the recovery partition is intact,but i cant access it,even when setting a boot flag on it. i am stumped and i really need answers thanks in advance! specs Toshiba satellite l775 intel core i3 dual core processor original os:windows 7 home premium 64 bit sp1 let me know if you need more info!

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• I can't program because the code I am using uses old coding styles. Is this normal to programmers? [closed]

  - by Renato Dinhani Conceição

  I'm in my first real job as programmer, but I can't solve any problems because of the coding style used. The code here: Does not have comments Does not have functions (50, 100, 200, 300 or more lines executed in sequence) Uses a lot of if statements with a lot of paths Has variables that make no sense (eg.: cf_cfop, CF_Natop, lnom, r_procod) Uses an old language (Visual FoxPro 8 from 2002), but there are new releases from 2007. I feel like I have gone back to 1970. Is it normal for a programmer familiar with OOP, clean-code, design patterns, etc. to have trouble with coding in this old-fashion way? EDIT: All the answers are very good. For my (un)hope, appears that there are a lot of this kind of code bases around the world. A point mentioned to all answers is refactor the code. Yeah, I really like to do it. In my personal project, I always do this, but... I can't refactor the code. Programmers are only allowed to change the files in the task that they are designed for. Every change in old code must be keep commented in the code (even with Subversion as version control), plus meta informations (date, programmer, task) related to that change (this became a mess, there are code with 3 used lines and 50 old lines commented). I'm thinking that is not only a code problem, but a management of software development problem.

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• WIN7 and Ubuntu lost after Installing ubuntu 12.04 and win7 dual system ,I have no OS on my laptop now

  - by abos

  Here is the procedure: In the morning I installed ubuntu using a USB directly without config any thing to my win7 system. After install complete, ubuntu installation software tell me to reboot.And everything is just find. While rebooting, there is NO UBUNTU system for me to select,and my laptop go straight to log in using WIN7. NO ubuntu shows on WIN7's configuration(Default System). Log in ubuntu using usb(try ubuntu without installation), I can find ubuntu's filesystem was already there. Formatting the disk on WIN7's disk management, rearranging them to other disk.Still having no trouble with WIN7. In the afternoon try a few times of installation and uninstallation of ubuntu. still shows no sign of selecting ubuntu system. In the evening another trial while installing ubuntu with the third option of: installing ubuntu alongside with INW7, erase win7 and install ubuntu. somethingelse --- my check failed with configuartion for what comes out with the 'something else' option,reboot. And I have no system now with some cmd tips say: Reboot and Select proper Boot Device or Insert Boot Media in selected Boot device and press a key. Files those on win7's orginal file system and Ubuntu filesystem can still be found when I 'try ubuntu without installation'. 5.But I just got no OS when I reboot my laptop normally.

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• Why won't my graphics work in Ubuntu 12.04 LTS?

  - by user170974

  I'm very new to Ubuntu and to Linux in general, and took the leap and formatted my PC to Ubuntu 12.04 LTS very recently :) I seem to be having some trouble getting my graphics card to run properly, I looked over what information I could find but I still cannot get it up and running and figured this was a good place to ask for help. The information I can find on my graphics is as follows: (Terminal command) lspci outputs: 01:05.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RS880M [Mobility Radeon HD 4225/4250] 02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Madison [Mobility Radeon HD 5650/5750 / 6530M/6550M] I tried using a mixture of the following links: How do I fix my installation of ATI Catalyst Video Driver in 12.04 LTS? What is the correct way to install ATI Catalyst Video Drivers (fglrx)? Ubuntu Precise Installation Guide But it does not seem to work, since running fglrxinfo in terminal gives: display: :0.0 screen: 0 OpenGL vendor string: VMware, Inc. OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 0x301) OpenGL version string: 1.4 (2.1 Mesa 9.0.3) What am I doing wrong here? All help appreciated ;) Edit: I have tried the legacy driver from www2.ati.com/drivers/linux/amd-driver-installer-catalyst-13-4-linux-x86.x86_64.zip I also tried the guide at https://launchpad.net/~makson96/+archive/fglrx which caused the system to crash (blackscreen, no boot) Neither seemed to work. I did however reinstall ubuntu 12.04 LTS, and re-tried both with no success. Reintalling ubuntu did however fix the broken dependencies problems, etc.

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• How do I get 1366x768 resolution on 12.04?

  - by Megan

  I am on an HP Envy 14, and the proper resolution that I should be using is 1366x768. This is not an option and I am stuck on 1024x768. I am using Linux 12.04. lspci | grep VGA: 00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Madison [Radeon HD 5000M Series] I've tried to add the resolution as a mode in xorg.conf but that does not work. Please any help would be appreciated. I'm new to Linux and just got my dual boot working but this resolution issue is killing me. Edit1 I just tried using the xrandr command: xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync But I get an error: xrandr: Failed to get size of gamma for output default Edit2 lsmod returns the following: Module Size Used by vesafb 13844 1 rfcomm 47604 12 bnep 18281 2 parport_pc 32866 0 ppdev 17113 0 snd_hda_codec_hdmi 32474 1 arc4 12529 2 joydev 17693 0 hid_logitech_dj 18594 0 i915 472941 5 uvcvideo 72627 0 usbhid 47199 1 hid_logitech_dj hid 99559 2 hid_logitech_dj,usbhid psmouse 87692 0 iwlwifi 332525 0 mac80211 506816 1 iwlwifi videodev 98259 1 uvcvideo snd_hda_codec_idt 70795 1 mei 41616 0 btusb 18288 2 v4l2_compat_ioctl32 17128 1 videodev hp_accel 25976 0 lis3lv02d 19876 1 hp_accel hp_wmi 18092 0 sparse_keymap 13890 1 hp_wmi input_polldev 13896 1 lis3lv02d drm_kms_helper 46978 1 i915 drm 242038 2 i915,drm_kms_helper i2c_algo_bit 13423 1 i915 serio_raw 13211 0 snd_hda_intel 33773 5 snd_hda_codec 127706 3 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_hda_intel snd_hwdep 13668 1 snd_hda_codec bluetooth 180104 23 rfcomm,bnep,btusb cfg80211 205544 2 iwlwifi,mac80211 snd_pcm 97188 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec mac_hid 13253 0 snd_seq_midi 13324 0 snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi snd_seq 61896 2 snd_seq_midi,snd_seq_midi_event fglrx 3263886 0 snd_timer 29990 2 snd_pcm,snd_seq snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq snd 78855 20 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_ra wmidi,snd_seq,snd_timer,snd_seq_device wmi 19256 1 hp_wmi video 19596 1 i915 intel_ips 18174 0 soundcore 15091 1 snd snd_page_alloc 18529 2 snd_hda_intel,snd_pcm lp 17799 0 parport 46562 3 parport_pc,ppdev,lp r8169 62099 0 I have installed ATI/AMD proprietary FGLRX graphics driver. But there is another one called ATI/AMD proprietary FGLRX graphics driver (post-release updates) which I have trouble installing because it gives me an error and tells me to look at some sort of jockey log.

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• Whole continent simulation [on hold]

  - by user2309021

  Let's suppose I am planning to create a simulation of an entire continent at some point in the past (let's say, around 0 A.D). Is it feasible to spawn a hundred million actors that interact with each other and their environments? Having them reproduce, extract resources, etc? The fact is that I actually want to create a simulation that allows me to zoom in from a view of the entire continent up to a single village, and interact with it. (Think as if you could keep zooming in the campaign map of any Total War game and the transition to the battle map was seamless, not a change of the "game mode"). By the way, I have never made a game in my entire life (I have programmed normal desktop applications, though), so I am really having trouble wrapping my head around how to implement such a thing. Even while thinking about how to implement a simple population simulator, without a graphical interface, I think that the O(n) complexity of traversing an array and telling all people to get one year older each time the program ticks is kind of stupid. Any kind help would be greatly appreciated :) EDIT: After being put on hold, I shall specify a question. How would you implement a simulation of all basic human dynamics (reproduction, resource consumption) in an entire continent (with millions of people)?

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• Does it make sense to write tests for legacy code when there is no time for a complete refactoring?

  - by is4

  I usually try to follow the advice of the book Working Effectively with Legacy Code. I break dependencies, move parts of the code to @VisibleForTesting public static methods and to new classes to make the code (or at least some part of it) testable. And I write tests to make sure that I don't break anything when I'm modifying or adding new functions. A colleague says that I shouldn't do this. His reasoning: The original code might not work properly in the first place. And writing tests for it makes future fixes and modifications harder since devs have to understand and modify the tests too. If it's GUI code with some logic (~12 lines, 2-3 if/else block, for example), a test isn't worth the trouble since the code is too trivial to begin with. Similar bad patterns could exist in other parts of the codebase, too (which I haven't seen yet, I'm rather new); it will be easier to clean them all up in one big refactoring. Extracting out logic could undermine this future possibility. Should I avoid extracting out testable parts and writing tests if we don't have time for complete refactoring? Is there any disadvantage to this that I should consider?

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• Ubuntu 13.10, kernel 3.11 blank screen issue with hybrid graphics

  - by Lagerbaer

  On my HP Envy, which has both an Intel on-chip graphics card and an Nvidia Geforce: *-display UNCLAIMED description: 3D controller product: GK208M [GeForce GT 740M] vendor: NVIDIA Corporation physical id: 0 bus info: pci@0000:01:00.0 version: a1 width: 64 bits clock: 33MHz capabilities: cap_list configuration: latency=0 resources: memory:d2000000-d2ffffff memory:a0000000-afffffff memory:b0000000-b1ffffff ioport:5000(size=128) memory:b2000000-b207ffff *-display description: VGA compatible controller product: 4th Gen Core Processor Integrated Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 06 width: 64 bits clock: 33MHz capabilities: vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:46 memory:d3000000-d33fffff memory:c0000000-cfffffff ioport:6000(size=64) I have trouble with all newer kernels. I basically had to install 12.04 LTS and use their 3.5 kernel family to get the system to boot. The 3.8 from 12.10 or the newest 3.11 from Ubuntu 13.10 leave me with a black screen upon boot. On one occasion I did hear the "log in" sound, but the screen did not display anything. I have purged all nvidia drivers so I guess it should just use the intel drivers, but apparently this is all messed up with newer kernel versions. This is different from the other "nvidia boots into blank screen" bug in that I don't rely solely on an nvidia card. Surely the intel on-chip card should be supported and leave me with something different from a blank screen? Again, it only works with kernel versions 3.5.0-41-generic, not with the 3.11.0-12 one that ships with Ubuntu 13.10. When I go into the grub menu and change the boot options from 'quiet splash' to 'nomodeset' I am able to boot the system, but then I don't get any graphics and trying 'sudo service lightdm start' doesn't succeed (I get 100% CPU for apport, but this doesn't do anything either, so I kill it). Help, I'm all out of ideas. EDIT: Let me add that I'm using the EFI boot system and have a dual-boot installation with Windows 8.

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• Point in Polygon, Ray Method: ending infinite line

  - by user2878528

  Having a bit of trouble with point in polygon collision detection using the ray method i.e. http://en.wikipedia.org/wiki/Point_in_polygon My problem is I need to give an end to the infinite line created. As with this infinite line I always get an even number of intersections and hence an invalid result. i.e. ignore or intersection to the right of the point being checked what I have what I want My current code based of Mecki awesome response for (int side = 0; side < vertices.Length; side++) { // Test if current side intersects with ray. // create infinite line // See: http://en.wikipedia.org/wiki/Linear_equation a = end_point.Y - start_point.Y; b = start_point.X - end_point.X; c = end_point.X * start_point.Y - start_point.X * end_point.Y; //insert points of vector d2 = a * vertices[side].Position.X + b * vertices[side].Position.Y + c; if (side - 1 < 0) d1 = a * vertices[vertices.Length - 1].Position.X + b * vertices[vertices.Length - 1].Position.Y + c; else d1 = a * vertices[side-1].Position.X + b * vertices[side-1].Position.Y + c; // If points have opposite sides, intersections++; if (d1 > 0 && d2 < 0 ) intersections++; if (d1 < 0 && d2 > 0 ) intersections++; } //if intersections odd inside = true if ((intersections % 2) == 1) inside = true; else inside = false;

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• C++ program...overshoots? [migrated]

  - by Zdrok

  I'm decent at C++, but I may have missed some nuance that applies here. Or maybe I completely missed a giant concept, I have no idea. My program was instantly crashing ("blah.exe is not responding") about 1/5 times it was run (other times it ran completely fine) and I tracked the problem down to a constructor for a world class that was called once in the beginning of the main function. Here is the code (in the constructor) that causes the problem: int ii; for(ii=0;ii<=255;ii++) { cout<<"ent "<<ii<<endl; entity_list[ii]=NULL; } for(ii=0;ii<=255;ii++) { cout<<"sec "<<ii<<endl; sector_list[ii]=NULL; } entity_list[0] = new Entity(0,0); entity_list[0]->_world = this; Specifically the second for loop. The cout references are new for the sake of telling where it is having trouble. It would print the entire "ent 1" to "ent 255" and then "sec 1" to "sec 255" and then crash right after, as if it was going for a 257th run through of the second for loop. I set the second for loop to go until "ii<=254" which stopped all crashes. Does C++ code tend to "overshoot" for loops or something? What is causing it to crash at this specific loop seemingly at random? By the way, entity_list and sector_list point to classes called Entity and Sector, respectively, but they are not constructing anything so I didn't think it would be relevant. I also have a forward declaration for the Entity class in a header for this, but since none were being constructed I didn't think it was relevant either. EDIT: It was due to the new Entity line, I assumed wrongly that the fact that altering the for statement to 254 fixed the crashes meant that it had to be there. I still don't understand why the for loop is related, though.

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• Webmatrix The Site has Stopped Fix

  - by Tarun Arora

  I just got started with AzureWebSites by creating a website by choosing the Wordpress template. Next I tried to install WebMatrix so that I could run the website locally. Every time I tried to run my website from WebMatrix I hit the message “The following site has stopped ‘xxx’” Step 00 – Analysis It took a bit of time to figure out that WebMatrix makes use of IISExpress. But it was easy to figure out that IISExpress was not showing up in the system tray when I started WebMatrix. This was a good indication that IISExpress is having some trouble starting up. So, I opened CMD prompt and tried to run IISExpress.exe this resulted in the below error message So, I ran IISExpress.exe /trace:Error this gave more detailed reason for failure Step 1 – Fixing “The following site has stopped ‘xxx’” Further analysis revealed that the IIS Express config file had been corrupted. So, I navigated to C:\Users\<UserName>\Documents\IISExpress\config and deleted the files applicationhost.config, aspnet.config and redirection.config (please take a backup of these files before deleting them). Come back to CMD and run IISExpress /trace:Error IIS Express successfully started and parked itself in the system tray icon. I opened up WebMatrix and clicked Run, this time the default site successfully loaded up in the browser without any failures. Step 2 – Download WordPress Azure WebSite using WebMatrix Because the config files ‘applicationhost.config’, ‘aspnet.config’ and ‘redirection.config’ were deleted I lost the settings of my Azure based WordPress site that I had downloaded to run from WebMatrix. This was simple to sort out… Open up WebMatrix and go to the Remote tab, click on Download Export the PublishSettings file from Azure Management Portal and upload it on the pop up you get when you had clicked Download in the previous step Now you should have your Azure WordPress website all set up & running from WebMatrix. Enjoy!

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• Can't get directory listing on my Apache to work.

  - by joon

  Hi, I'm having trouble enabling the directory listing on apache. I did it a few weeks ago but had to reinstall cause my Wubi ran out of space, and now I can't get it to work and it's driving me crazy. I have a folder /home/joon/Dropbox/Projects/apache, which I want to set as the root for my apache. Here's the first lines of the 'default' file in the sites-available folder: <VirtualHost *:8888> ServerAdmin webmaster@localhost DocumentRoot /home/joon/Dropbox/Projects/apache <Directory /home/joon/Dropbox/Projects/apache> Options +Indexes FollowSymLinks AllowOverride None The rest is unchanged. Ports.conf is set to Listen 8888. I thought the +Indexes should do it, but I must have overlooked something. I get a 403, forbidden. "You don't have permission to access / on this server." If I input the url of an image, http://127.0.0.1:8888/joon/bin/1chart.png, it displays, but no directory listing. Please help.

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• snapping an angle to the closest cardinal direction

  - by Josh E

  I'm developing a 2D sprite-based game, and I'm finding that I'm having trouble with making the sprites rotate correctly. In a nutshell, I've got spritesheets for each of 5 directions (the other 3 come from just flipping the sprite horizontally), and I need to clamp the velocity/rotation of the sprite to one of those directions. My sprite class has a pre-computed list of radians corresponding to the cardinal directions like this: protected readonly List<float> CardinalDirections = new List<float> { MathHelper.PiOver4, MathHelper.PiOver2, MathHelper.PiOver2 + MathHelper.PiOver4, MathHelper.Pi, -MathHelper.PiOver4, -MathHelper.PiOver2, -MathHelper.PiOver2 + -MathHelper.PiOver4, -MathHelper.Pi, }; Here's the positional update code: if (velocity == Vector2.Zero) return; var rot = ((float)Math.Atan2(velocity.Y, velocity.X)); TurretRotation = SnapPositionToGrid(rot); var snappedX = (float)Math.Cos(TurretRotation); var snappedY = (float)Math.Sin(TurretRotation); var rotVector = new Vector2(snappedX, snappedY); velocity *= rotVector; //...snip private float SnapPositionToGrid(float rotationToSnap) { if (rotationToSnap == 0) return 0.0f; var targetRotation = CardinalDirections.First(x => (x - rotationToSnap >= -0.01 && x - rotationToSnap <= 0.01)); return (float)Math.Round(targetRotation, 3); } What am I doing wrong here? I know that the SnapPositionToGrid method is far from what it needs to be - the .First(..) call is on purpose so that it throws on no match, but I have no idea how I would go about accomplishing this, and unfortunately, Google hasn't helped too much either. Am I thinking about this the wrong way, or is the answer staring at me in the face?

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• Update Manager got stuck (but not frozen) while installing downloaded updates. What should I do?

  - by WarriorIng64

  I have just gotten my Ubuntu 12.04 LTS desktop computer reassembled after a trip back home and connected it to my parent's wireless Internet connection. The connection seems quite shaky (disconnects half the time, likely an ongoing issue with the wireless card I have installed), and it struggled to download updates because of the constant interruptions. Eventually, it managed to download the updated packages and started installing them. I got up and left it to do its work. When I came back, I saw it was still having trouble staying connected to the wireless (no surprise there), but then I noticed that it seemed like Update Manager had stopped making progress on the installation. I opened the Details pane to see what it was last doing: My guess was that the installation script for flashplugin-installer couldn't complete the download until I stabilized the Internet connection. I hooked my Ubuntu laptop up to my desktop via Ethernet and shared its wireless connection using this guide, and as I am typing this now from my desktop you can see that the connection issue was successfully worked around. However, even with a stable connection established, Update Manager seems "stuck" at its current position and won't go any further. It's not totally frozen, but I can't do anything beyond open/close the Details pane as the Cancel button is grayed out. I know it can cause big problems if updates are stopped during installation, but I'm at a loss as to how this situation should be handled. I'm sure it should finish normally if I can just find a way to restart Update Manager, but the question is how this should be approached. How can I safely get my updates to finish installing?

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• Using a random string to authenticate HMAC?

  - by mrwooster

  I am designing a simple webservice and want to use HMAC for authentication to the service. For the purpose of this question we have: a web service at example.com a secret key shared between a user and the server [K] a consumer ID which is known to the user and the server (but is not necessarily secret) [D] a message which we wish to send to the server [M] The standard HMAC implementation would involve using the secret key [K] and the message [M] to create the hash [H], but I am running into issues with this. The message [M] can be quite long and tends to be read from a file. I have found its very difficult to produce a correct hash consistently across multiple operating systems and programming languages because of hidden characters which make it into various file formats. This is of course bad implementation on the client side (100%), but I would like this webservice to be easily accessible and not have trouble with different file formats. I was thinking of an alternative, which would allow the use a short (5-10 char) random string [R] rather than the message for autentication, e.g. H = HMAC(K,R) The user then passes the random string to the server and the server checks the HMAC server side (using random string + shared secret). As far as I can see, this produces the following issues: There is no message integrity - this is ok message integrity is not important for this service A user could re-use the hash with a different message - I can see 2 ways around this Combine the random string with a timestamp so the hash is only valid for a set period of time Only allow each random string to be used once Since the client is in control of the random string, it is easier to look for collisions I should point out that the principle reason for authentication is to implement rate limiting on the API service. There is zero need for message integrity, and its not a big deal if someone can forge a single request (but it is if they can forge a very large number very quickly). I know that the correct answer is to make sure the message [M] is the same on all platforms/languages before hashing it. But, taking that out of the equation, is the above proposal an acceptable 2nd best?

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• Is there a schematic overview of Ubuntu's architecture?

  - by joebuntu

  Hi there, as enthusiastic, advanced Linux learner, I'd love to get an overview about Linux' architecure/structure in general. You know, like "the big picture". I'm thinking of a large schematic graphic showing what is what, who is who, what system (e.g. X) comprises which subsystems (GDM/Gnome/Compiz) on the way from a to z, from boot to interactive desktop, including the most important background services (auth, network, cron, ...). Maybe a bit like this: http://www.flickr.com/photos/pgc/140859386/ but way more detailed. There's bootchart, which produces very comprehensive charts, but they again are too detailed and difficult to get the "big picture" from. Is there such a thing? Possibly not for the whole System, but maybe for single subsystems? I had trouble searching for this, because using search terms like "scheme" or "architecture" pointed to the wrong direction (a tool called "scheme" or CAD software for linux). I appreciate any links. If there's interest in those schematic overviews and links, maybe someone could turn this post into a wiki post? Cheers, joebuntu

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• What are some good ways for an intermediate programmer to build skills?

  - by Jordan

  Preface: I work mostly in Python, and Web Dev languages (HTML, CSS, Javascript and Jquery, PHP) I'm proficient at coding but I want to get better. In larger more advanced projects my programming skills break down. The more code there is the more trouble I have fitting all the pieces together. I understand syntax well, and I can catch and correct errors fairly easier. But the more advanced it gets the more I struggle. I believe I have a good understand of the basic and nuts and bolts of programming and I understand what's going on, but when it comes to larger projects, especially ones with heavy math involved my confidence flags and I start making mistakes. It's not that I can't do it, I'm just not used to doing it. Does anyone have any advice for someone who knows programming, but wants to get better? The only tutorials I can really find are beginner basic type stuff. Basically what I'm saying is I want to be confident when I'm tackling advanced projects, but I can't because I have little experience dealing with difficult situations.

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• Ubuntu server is dropping SSH connections, then not allowing me to log back on

  - by wilhil

  I have an ESX box which I have loaded with two Ubuntu Server machines. During setup, I chose no additional packages to install as I just wanted a lightweight machine for testing. The first thing I did was change the root password via sudo passwd After ESX got on my nerves through lag, I decided to install OpenSSH via apt-get install openssh-server. It did it's business, and I then opened putty and could connect in to both machines fine. The first time it connected, it asked me to add the ssh key as obviously it did not know it. Anyway, the second server is working flawlessly, but, the first seems to be giving me trouble. I was in the middle of typing a sentence when it kicked me off for no reason and when I tried to reconnect, putty gave me a warning that the ssh key had changed and it is potentially dangerous. I attempted to log in anyway and it did not work, just the standard access denied message. Using the second machine, I SSHed in to the first machine and it worked straight away, I then killed the SSH sessions (and possibly SSH server), I then reconnected via putty and I again received the security warning message, but, it allowed me to log on fine. ... I thought "glitch" and nothing more of it, but, it just happened again! I really do not understand this and was hoping someone here can help?

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• Failed 11.10 to 12.04 upgrade and drove me crazy!

  - by Ivan

  Please help me with this! I first tried to upgrade my Ubuntu server from 11.10 to 12.04 thru Upgrade Manager, but never succeeded! Then I tried upgrading thru terminal, which took me ~4 hours as I was warned. When I restarted my computer, my login GUI did not show up at all! (Panic I was!) But when I switched to tty6 and it seemed the upgrade has finished, at least partially and got message Ubuntu 12.04LTS and telling me 12.10 is available. There are bunch of unmet dependencies...."apt-get install -f" may resolve the problem. Then I tried: sudo apt-get -f install, did not succeed! Also I tried sudo apt-get update && sudo apt-get upgrade I got bunch of error message too long to list here. Then I tried: sudo do-release-upgrade still bunch of error message there! There seems a lot trouble with the upgrade from 11.10 to 12.04 for me. Did I miss anything? Anyway, can I ask how I can get the gnome login GUI back? Thanks a lot! Yifang

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• Ubuntu live cd : black screen and blinking cursor

  - by IFasel

  I try to install ubuntu 12.04 on my computer. I can get to the purple screen on the live cd but then, if I choose "Installing Ubuntu", I have a black screen with a cursor blinking (and nothing else happens). My PC : acer aspire M3920, CPU i5-2300, 8 Gb RAM, NVIDIA gt 405. What I already tried : I tried with 12.04 and 13.04 daily build I tried with a live usb and with a live dvd I tried the following boot options : nomodset, acpi=off I googled a lot and it seems that it could be a graphic card problem. Do you know any other boot options that I could try ? UPDATE This is not a duplicate : I've tried all the common boot options (nomodeset, noacpi...) and it doesn't change anything. With the option "no splash" (instead of "quiet splash"), I can see what happens before the forever-blinking cursor : [sdg] no caching mode present [sdg] assuming drive cache : write trough ata8.00: excetion Emask 0x52 ... frozen ata8 : SError : { RecovData RecovComm UnrecovData...} ata8.00 : failed command : IDENTIFY PACKET DEVICE ... ata8.00 : status : { DRDY } ata8 : hard resetting link Does somebody know what it means ? N.B. astonishingly, Puppy Linux boots fine (but Debian, Fedora and Ubuntu do not) Solution In fact, it was not a graphic card problem. I had to disconnect the dvd drive and connect it to another free sata connector (I don't really understand why Ubuntu had trouble with this connector and Windows 7 not). After that, everything worked fine.

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• Problems after installing a plethora of updates

  - by box

  yesterday I decided to install 32-bit Ubuntu on my 64-bit desktop, first of all, is that a problem? After installing, i had around 270 updates to install, according to the update manager. I was having trouble launching a game with WINE, so I thought updating might help. After updating, I restarted my computer, and after a long while it showed me my desktop and the icon's on it, but I didn't get anything else. I didn't have the "taskbar" (not sure what it's called, sue me) on the left side, nor the bar at the top. I also received an error message saying some program had stopped working. I decided to restart my computer again, and that was when it told me that i have to re-configure my drivers, or run in "Low Graphics" mode for one session, amongst other options. Well, I decided to try to revert to the "basic video drivers", which was an option it gave. Restarting the computer gave me the same problem as in the second paragraph. After a few more restarts and a night of restless sleep, here I am trying to start my computer again, only to receive a black screen, and my monitor "going to sleep". I'm sort of stumped here, being new to Ubuntu (desktop, at least) and I really hope this gets fixed without me having to install Ubuntu on yet another partition (I have three other partitions for various things already) tl;dr: Black screen on boot after installing updates.

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• Run script at user login as root, with a catch

  - by tubaguy50035

  I'm trying to run a PHP script as root on user login. The PHP script adds a Samba share to the Samba config, thus the need for root privileges. The only issue here, is that the user doesn't exist yet. This system is integrated with active directory. So when a user logs in for the first time, a home directory for them is created under /home/DOMAIN/username. I've found this question and that seems like the correct way to get what I want, but I'm having trouble with the syntax since I don't know the user's name. Would it be something like: ALL ALL=(ALL) NOPASSWD: /home/DOMAIN/*/createSambaShare.php This doesn't seem to work as it is currently. Anyone have any ideas or a "scripted" way to add a Samba share on user login? Since I've made other changes to /etc/skel, I just added the bash necessary to run the PHP script in .profile in there. This then gets copied to the "new" user's home and it tries to run the PHP script. But it fails, because these are not privileged users. Changing permissions on the PHP script will not help. It needs to be run as sudo because it opens the Samba config file for writing. Letting any user run the PHP script would result in a PHP error. The homes Samba directive doesn't work for my use case. I need the Samba share to exist once they exist on the server, even when they're not logged in.

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• Trying to make a game with C++, using lists to store bullets and enemies, but they are not erased

  - by XD_dued

  I've been trying to make a pretty simple space shooter game with C++, and I have been having a lot of trouble trying to use lists to store enemies and bullets. Basically I followed the post here almost exactly to store my bullets: SDL Bullet Movement I've done something similar to store my enemies. However, when I call bullets.erase(it++), for some reason the bullet is not erased. When the bullet movement is run for the next frame, it tries to re delete the bullet and segfaults the program. When I comment out the erase line, it runs fine, but the bullets are then never erased from the list... Is there any reason why the elements of the list aren't being deleted? I also set it up to print the number of elements in the list for every iteration, and it does not go down after deleting. Thanks! EDIT: Here's the specific code I'm using to store my enemies and having them act: std::list<Grunt*> doGrunts(std::list<Grunt*> grunts) { for(std::list<Grunt*>::iterator it = grunts.begin(); it != grunts.end();) { if((*it)->getHull() == 0) { delete * it; grunts.erase(it++); } else { (**it).doUnit(grunts, it); ++it; } } } Grunt is my enemy class, and the list grunts is a global variable. Is that my problem? When I pass the global into the function it becomes local? I assumed lists would be a reference type so thought this wouldn't be a problem. Sorry if this was a dumb question, I'm very new to C++, this is the first major thing I'm working on.

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