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• Low Latency Serial Communications In .Net

  - by bvillersjr

  I have been researching various third party libraries and approaches to low latency serial communications in .Net. I've read enough that I have now come full circle and know as little as I did when I started due to the variety of conflicting opinions. For example, the functionality in the Framework was ruled out due to some convincing articles stating: "that the Microsoft provided solution has not been stable across framework versions and is lacking in functionality." I have found articles bashing many of the older COM based libraries. I have found articles bashing the idea of a low latency .Net app as a whole due to garbage collection. I have also read articles demonstrating how P/Invoking Windows API functionality for the purpose of low latency communication is unacceptable. THIS RULES OUT JUST ABOUT ANY APPROACH I CAN THINK OF! I would really appreciate some words from those with been there / done that experience. Ideally, I could locate a solid library / partner and not have to build the communications library myself. I have the following simple objectives: Sustained low latency serial communication in C# / VB.Net 32/64 bit Well documented (if the solution is 3rd party) Relatively unimpacted (communication and latency wise) by garbage collection . Flexible (I have no idea what I will have to interface with in the future!) The only requirement that I have for certain is that I need to be able to interface with many different industrial devices such as RS485 based linear actuators, serial / microcontroller based gauges, and ModBus (also RS485) devices. Any comments, ideas, thoughts or links to articles that may iron out my confusion are much appreciated!

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• What are the limitations of the .NET Assembly format?

  - by McKAMEY

  We just ran into an interesting issue that I've not experienced before. We have a large scale production ASP.NET 3.5 SP1 Web App Project in Visual Studio 2008 SP1 which gets compiled and deployed using a Website Deployment Project. Everything has worked fine for the last year, until after a check-in yesterday the app started critically failing with BadImageFormatException. The check-in in question doesn't change anything particularly special and the errors are coming from areas of the app not even changed. Using Reflector we inspected the offending methods to find that there were garbage strings in the code (which Reflector humorously interpreted as Chinese characters). We have consistently reproduced this on several machines so it does not appear to be hardware related. Further inspection showed that those garbage strings did not exist in the Assemblies used as inputs to aspnet_merge.exe during deployment. Web Deployment Project Output Assemblies Properties: Merge all outputs to a single assembly Merge each individual folder output to its own assembly Merge all pages and control outputs to a single assembly Create a separate assembly for each page and control output In the web deployment project properties if we set the merge options to the first option ("Merge all outputs to a single assembly") we experience the issue, yet all of the other options work perfectly! So my question: does anyone know why this is happening? Is there a size-limit to aspnet_merge.exe's capabilities (the resulting merged DLL is around 19.3 MB)? Are there any other known issues with merging the output of WAPs? I would love it if any Assembly format / aspnet_merge gurus know about any such limitations like this. Seems to me like a 25MB Assembly, while big, isn't outrageous. Less disk to hit if it is all pregen'd stuff.

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• thread reaches end but isn't removed

  - by pstanton

  I create a bunch of threads to do some processing: new Thread("upd-" + id){ @Override public void run(){ try{ doSomething(); } catch (Throwable e){ LOG.error("error", e); } finally{ LOG.debug("thread death"); } } }.start(); I know i should be using a threadPool but i need to understand the following problem before i change it: I'm using eclipse's debugger and looking at the threads in the debug pane which lists active threads. Many of them complete as you would expect, and are removed from the debug pane, however some seem to stay in the list of active threads even though the log shows the "thread death" entry for these. When i attempt to debug these threads, they either do not pause for debugging or show an error dialog: "A timeout occurred while retrieving stack frames for thread: upd-...". there is some synchronization going on within the doSomething() call but i'm fairly sure it's ok and since the "thread death" log is being called i'm assuming these threads aren't deadlocked in that method. i don't do any Thread.join()s, however i do call a third party API but doubt they do either. Can anyone think of another reason these threads are lingering? Thanks. EDIT: I created this test to check the Garbage Collection theory: Thread thread = new Thread("!!!!!!!!!!!!!!!!") { @Override public void run() { System.out.println("running"); ThreadUs.sleepQuiet(5000); System.out.println("finished"); // <-- thread removed from list here } }; thread.start(); ThreadUs.sleepQuiet(10000); System.out.println(thread.isAlive()); // <-- thread already removed from list but hasn't been GC'd ThreadUs.sleepQuiet(10000); this proves that it is nothing to do with garbage collection as eclipse removes the thread from the thread list as soon as it completes and isn't waiting for the object to be de-referenced/GC'd.

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• Are there size limitations to the .NET Assembly format?

  - by McKAMEY

  We ran into an interesting issue that I've not experienced before. We have a large scale production ASP.NET 3.5 SP1 Web App Project in Visual Studio 2008 SP1 which gets compiled and deployed using a Website Deployment Project. Everything has worked fine for the last year, until after a check-in yesterday the app started critically failing with BadImageFormatException. The check-in in question doesn't change anything particularly special and the errors are coming from areas of the app not even changed. Using Reflector we inspected the offending methods to find that there were garbage strings in the code (which .NET Reflector humorously interpreted as Chinese characters). We have consistently reproduced this on several machines so it does not appear to be hardware related. Further inspection showed that those garbage strings did not exist in the Assemblies used as inputs to aspnet_merge.exe during deployment. aspnet_merge.exe / Web Deployment Project Output Assemblies Properties: Merge all outputs to a single assembly Merge each individual folder output to its own assembly Merge all pages and control outputs to a single assembly Create a separate assembly for each page and control output In the web deployment project properties if we set the merge options to the first option ("Merge all outputs to a single assembly") we experience the issue, yet all of the other options work perfectly! My question: does anyone know why this is happening? Is there a size-limit to aspnet_merge.exe's capabilities (the resulting merged DLL is around 19.3 MB)? Are there any other known issues with merging the output of WAPs? I would love it if any Assembly format / aspnet_merge.exe gurus know about any such limitations like this. Seems to me like a 25MB Assembly, while big, isn't outrageous.

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• Issue encondig java->xls

  - by Xerg

  This is not a pure java question and can also be related to HTML I've written a java servlet that queries a database table and shows the result as a html table. The user can also ask to receive the result as an Excel sheet. Im creating the Excel sheet by printing the same html table, but with the content-type of "application/vnd.ms-excel". The Excel file is created fine. The problem is that the tables may contain non-english data so I want to use a UTF-8 encoding. PrintWriter out = response.getWriter(); response.setContentType("application/vnd.ms-excel:ISO-8859-1"); //response.setContentType("application/vnd.ms-excel:UTF-8"); response.setHeader("cache-control", "no-cache"); response.setHeader("Content-Disposition", "attachment; filename=file.xls"); out.print(src); out.flush(); The non-english characters appear as garbage (áéíóú) Also I tried converting to bytes from String byte[] arrByte = src.getBytes("ISO-8859-1"); String result = new String(arrByte, "UTF-8"); But I Still getting garbage, What can I do?. Thanks

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• How to extract a 2x2 submatrix from a bigger matrix

  - by ZaZu

  Hello, I am a very basic user and do not know much about commands used in C, so please bear with me...I cant use very complicated codes. I have some knowledge in the stdio.h and ctype.h library, but thats about it. I have a matrix in a txt file and I want to load the matrix based on my input of number of rows and columns For example, I have a 5 by 5 matrix in the file. I want to extract a specific 2 by 2 submatrix, how can I do that ? I created a nested loop using : FILE *sample sample=fopen("randomfile.txt","r"); for(i=0;i<rows;i++){ for(j=0;j<cols;j++){ fscanf(sample,"%f",&matrix[i][j]); } fscanf(sample,"\n",&matrix[i][j]); } fclose(sample); Sadly the code does not work .. If I have this matrix : 5.00 4.00 5.00 6.00 5.00 4.00 3.00 25.00 5.00 3.00 4.00 23.00 5.00 2.00 352.00 6.00 And inputting 3 for row and 3 for column, I get : 5.00 4.00 5.00 6.00 5.00 4.00 3.00 25.00 5.00 Not only this isnt a 2 by 2 submatrix, but even if I wanted the first 3 rows and first 3 columns, its not printing it correctly.... I need to start at row 3 and col 3, then take the 2 by 2 submatrix ! I should have ended up with : 4.00 23.00 352.00 6.00 I heard that I can use fgets and sscanf to accomplish this. Here is my trial code : fgets(garbage,1,fin); sscanf(garbage,"\n"); But this doesnt work either :( What am I doing wrong ? Please help. Thanks !

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• Getting a nicely formatted timestamp without lots of overhead?

  - by Brad Hein

  In my app I have a textView which contains real-time messages from my app, as things happen, messages get printed to this text box. Each message is time-stamped with HH:MM:SS. Up to now, I had also been chasing what seemed to be a memory leak, but as it turns out, it's just my time-stamp formatting method (see below), It apparently produces thousands of objects that later get gc'd. For 1-10 messages per second, I was seeing 500k-2MB of garbage collected every second by the GC while this method was in place. After removing it, no more garbage problem (its back to a nice interval of about 30 seconds, and only a few k of junk typically) So I'm looking for a new, more lightweight method for producing a HH:MM:SS timestamp string :) Old code: /** * Returns a string containing the current time stamp. * @return - a string. */ public static String currentTimeStamp() { String ret = ""; Date d = new Date(); SimpleDateFormat timeStampFormatter = new SimpleDateFormat("hh:mm:ss"); ret = timeStampFormatter.format(d); return ret; }

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• Do COM Dll References Require Manual Disposal? If so, How?

  - by Drew

  I have written some code in VB that verifies that a particular port in the Windows Firewall is open, and opens one otherwise. The code uses references to three COM DLLs. I wrote a WindowsFirewall class, which Imports the primary namespace defined by the DLLs. Within members of the WindowsFirewall class I construct some of the types defined by the DLLs referenced. The following code isn't the entire class, but demonstrates what I am doing. Imports NetFwTypeLib Public Class WindowsFirewall Public Shared Function IsFirewallEnabled as Boolean Dim icfMgr As INetFwMgr icfMgr = CType(System.Activator.CreateInstance(Type.GetTypeFromProgID("HNetCfg.FwMgr")), INetFwMgr) Dim profile As INetFwProfile profile = icfMgr.LocalPolicy.CurrentProfile Dim fIsFirewallEnabled as Boolean fIsFirewallEnabled = profile.FirewallEnabled return fIsFirewallEnabled End Function End Class I do not reference COM DLLs very often. I have read that unmanaged code may not be cleaned up by the garbage collector and I would like to know how to make sure that I have not introduced any memory leaks. Please tell me (a) if I have introduced a memory leak, and (b) how I may clean it up. (My theory is that the icfMgr and profile objects do allocate memory that remains unreleased until after the application closes. I am hopeful that setting their references equal to nothing will mark them for garbage collection, since I can find no other way to dispose of them. Neither one implements IDisposable, and neither contains a Finalize method. I suspect they may not even be relevant here, and that both of those methods of releasing memory only apply to .Net types.)

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• Silverlight WinDg Memory Release Issue

  - by Chris Newton

  Hi, I have used WinDbg succesfully on a number of occasions to track down and fix memory leaks (or more accurately the CLRs inability to garbage collect a released object), but am stuck with one particular control. The control is displayed within a child window and when the window is closed a reference to the control remains and cannot be garbage collected. I have resolved what I believe to be the majority of the issues that could have caused the leak, but the !gcroot of the affected object is not clear (to me at least) as to what is still holding on to this object. The ouput is always the same regardless of the content being presented in the child window: DOMAIN(03FB7238):HANDLE(Pinned):79b12f8:Root: 06704260(System.Object[])- 05719f00(System.Collections.Generic.Dictionary2[[System.IntPtr, mscorlib],[System.Object, mscorlib]])-> 067c1310(System.Collections.Generic.Dictionary2+Entry[[System.IntPtr, mscorlib],[System.Object, mscorlib]][])- 064d42b0(System.Windows.Controls.Grid)- 064d4314(System.Collections.Generic.Dictionary2[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]])-> 064d4360(System.Collections.Generic.Dictionary2+Entry[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]][])- 064d3860(System.Windows.Controls.Border)- 064d4218(System.Collections.Generic.Dictionary2[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]])-> 064d4264(System.Collections.Generic.Dictionary2+Entry[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]][])- 064d3bfc(System.Windows.Controls.ContentPresenter)- 064d3d64(System.Collections.Generic.Dictionary2[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]])-> 064d3db0(System.Collections.Generic.Dictionary2+Entry[[MS.Internal.IManagedPeerBase, System.Windows],[System.Object, mscorlib]][])- 064d3dec(System.Collections.Generic.Dictionary2[[System.UInt32, mscorlib],[System.Windows.DependencyObject, System.Windows]])-> 064d3e38(System.Collections.Generic.Dictionary2+Entry[[System.UInt32, mscorlib],[System.Windows.DependencyObject, System.Windows]][])- 06490b04(Insurer.Analytics.SharedResources.Controls.HistoricalKPIViewerControl) If anyone has any ideas about what could potentially be the problem, or if you require more information, please let me know. Kind Regards, Chris

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• Webserver sending corrupt or corrupting served files

  - by NotIan

  EDIT: Looks like the problem was a rootkit that corrupted a bunch of low level linux commands, including top, ps, ifconfig, netstat and others. The problem was resolved by taking all web files off the server and wiping it. A dedicated server we operate is having a strange issue. Files are not be sent complete or are showing up with garbage data. Example: http://sustainablefitness.com/images/banner_bootcamps.jpg To make matters more confusing this corruption does NOT happen when the files are served as https, (I would post a link, but I don't have enough rep points, just add an 's' after http in the link above.) When I throw load at the server, I get dozens of (swapd)s in top this is the only thing that really jumps out. I can't post images but ( imgur.com / ZArSq.png ) is a screenshot of top. I have tried a lot of stuff so far, I am willing to try anything that I can. A dedicated server we operate is having a strange issue. Files are not be sent complete or are showing up with garbage data. Example: http://sustainablefitness.com/images/banner_bootcamps.jpg To make matters more confusing this corruption does NOT happen when the files are served as https, (I would post a link, but I don't have enough rep points, just add an 's' after http in the link above.) When I throw load at the server, I get dozens of (swapd)s in top this is the only thing that really jumps out. I can't post images but ( imgur.com / ZArSq.png ) is a screenshot of top. I have tried a lot of stuff so far, I am willing to try anything that I can.

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• Entangled text boxes

  - by user38329

  Hi StackOverflow, A mere Windows textbox greatly surprised me today. I have two unrelated text boxes inside an application. I can type in either text box and switch the focus by clicking on them. Then happens some event X, which I can't describe here for reasons given below. After this event happens, the two text boxes become "entangled" in an almost quantum way. Say, text box A was focused before X happened. When I click text box B to type in some text, the new text appears in text box A, whereas the blinking cursor happily moves along in text box B through the void, as if the text were there. No amount of clicking on either text boxes can resolve this. The cursor will always remain in B, whereas the text will always go to A. Message spying reveals that after the event X, the text boxes lose the ability to lose or gain focus. When I click on B, WM_LOSE_FOCUS does not come to A, and WM_SET_FOCUS does not come to B. (The rectangles and visibility of the boxes are OK.) The same thing happens in Windows XP and Windows 7. Now, event X: it's a big event in a third-party UI library which I cannot reverse-engineer in a timely manner. (Namely, docking a pane in wxAUI.) I am sure that this behavior is the result of incorrect WinAPI calls to the text boxes (garbage in - garbage out). I would like to know what could possibly cause such "textbox trip" to know where to start looking for the bug. Thanks!

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• Weird stuttering issues not related to GC.

  - by Smills

  I am getting some odd stuttering issues with my game even though my FPS never seems to drop below 30. About every 5 seconds my game stutters. I was originally getting stuttering every 1-2 seconds due to my garbage collection issues, but I have sorted those and will often go 15-20 seconds without a garbage collection. Despite this, my game still stutters periodically even when there is no GC listed in logcat anywhere near the stutter. Even when I take out most of my code and simply make my "physics" code the below code I get this weird slowdown issue. I feel that I am missing something or overlooking something. Shouldn't that "elapsed" code that I put in stop any variance in the speed of the main character related to changes in FPS? Any input/theories would be awesome. Physics: private void updatePhysics() { //get current time long now = System.currentTimeMillis(); //added this to see if I could speed it up, it made no difference Thread myThread = Thread.currentThread(); myThread.setPriority(Thread.MAX_PRIORITY); //work out elapsed time since last frame in seconds double elapsed = (now - mLastTime2) / 1000.0; mLastTime2 = now; //measures FPS and displays in logcat once every 30 frames fps+=1/elapsed; fpscount+=1; if (fpscount==30) { fps=fps/fpscount; Log.i("myActivity","FPS: "+fps+" Touch: "+touch); fpscount=0; } //this should make the main character (theoretically) move upwards at a steady pace mY-=100*elapsed; //increase amount I translate the draw to = main characters Y //location if the main character goes upwards if (mY<=viewY) { viewY=mY; } }

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• BufferedImage.getGraphics() resulting in memory leak, is there a fix?

  - by user359202

  Hi friends, I'm having problem with some framework API calling BufferedImage.getGraphics() method and thus causing memory leak. What this method does is that it always calls BufferedImage.createGraphics(). On a windows machine, createGraphics() is handled by Win32GraphicsEnvironment which keeps a listeners list inside its field displayChanger. When I call getGraphics on my BufferedImage someChart, someChart's SurfaceManager(which retains a reference to someChart) is added to the listeners map in Win32GraphicsEnvironment, preventing someChart to be garbage collected. Nothing afterwards removes someChart's SurfaceManager from the listeners map. In general, the summarized path stopping a BufferedImage from being garbage collected, once getGraphics is called, is as follows: GC Root - localGraphicsEnvironment(Win32GraphicsEnvironment) - displayChanger(SunDisplayChanger) - listeners(Map) - key(D3DChachingSurfaceManager) - bImg(BufferedImage) I could have changed the framework's code so that after every called to BufferedImage.getGraphics(), I keep a reference to the BufferedImage's SurfaceManager. Then, I get hold of localGraphicsEnvironment, cast it to Win32GraphicsEnvironment, then call removeDisplayChangedListener() using the reference to the BufferedImage's SurfaceManager. But I don't think this is a proper way to solve the problem. Could someone please help me with this issue? Thanks a lot!

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• How come the Actionscript 3 ENTER_FRAME event is crazy nuts?

  - by nstory

  So, I've been toying around with Flash, browsing through the documentation, and all that, and noticed that the ENTER_FRAME event seems to defy my expectation of a deterministic universe. Take the following example: (new MovieClip()).addEventListener(Event.ENTER_FRAME, function(ev) {trace("Test");}); Notice this anonymous MovieClip is not added to the display hierarchy, and any reference to it is immediately lost. It will actually print "Test" once a frame until it is garbage collected. How insane is that? The behavior of this is actually determined by when the garbage collector feels like coming around in all its unpredictable insanity! Is there a better way to create intermittent failures? Seriously. My two theories are that either the DisplayObject class stores weak references to all its instances for the purpose of dispatching ENTER_FRAME events, or, and much wilder, the Flash player actually scans the heap each frame looking for ENTER_FRAME listeners to pull on. Can any hardened Actionscript developer clue me in on how this works? (And maybe a why - the - f**k they thought this was a good idea?)

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• Which keymap to use for wired mac keyboard in Gentoo Linux?

  - by Absolute0

  I just purchase the new wired mac keyboard: Running on Gentoo Linux it works mostly fine. The only problem i am having is the function keys and swapping the alt and command keys to resemble a regular pc keyboard. When I tried switching to the "mac-us" keymap in /etc/conf.d/keymaps I got garbage when typing (not even qwerty). Is there any specific keymap that I can use to get what I want?

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• Has anyone gotten Plan9 working in VirtualBox?

  - by Electrons_Ahoy

  More than anything, I'm just curious to know if this is even possible, since Plan 9 isn't in the list of GuestOSes on the VirtualBox website. However, if someone out there has got it working, my specific question: Whenever I try to boot Plan9, either as a live cd or to install inside of VirtualBox, once the GUI loads all I get is a screen of garbage. I think I've tried just about every graphics driver combination at startup - specifically, even 640x480x8 in VESA mode didn't work. Any suggestions as to how I can load it?

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• Getting a hardware profile from Fedora 12 after installation

  - by Chris T

  I've installed Fedora 12 on a computer I found in the trash (Bulk garbage day!) and I'm trying to figure out what's under the hood (seems like a stock dell but I'd like to know the details). Is there a way to get a hardware profile on Fedora after it's already installed on the harddrive? I saw an option at install but I skipped over it.

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• Windows 7 120 GB disc drive C full

  - by user234570

  I have windows 7 and my disc drive has a capacity of 120 GB. From one day to another it tells me that my disc C is full in a red bar but I dont have many programs installed. I deleted all of my videos, games, music, pictures, etc and I was able to free up 30 GB. I ran the disk cleaner and emptied the TEMP folder and garbage can but it still shows a 70GB used. Can I get some help from the experts PLEASE!!!

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• Are memory leaks really something to worry about?

  - by chuck final

  I came across this post today, arguably debatable/wrong somewhat, but worth a shot looking over: http://andyharglesiscodebase.wordpress.com/2013/11/01/why-programmers-shouldnt-worry-about-memory-leaks/ The poster claims that modern OSes automatically have garbage collection implemented in the kernel memory, and that any unfreed user heap memory is managed during "post partum cleanup". It seems like rubbish, but I can't be 100% sure since I am not that knowledgeable on the kernel's memory management setup, etc.

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• Can I enable discards on a LUKS-encrypted ssd drive in RHEL6 (and do I need to)?

  - by Dan Nestor

  I have a RHEL 6.4 workstation, running on a LUKS-encrypted LV residing on a SSD. I found RedHat documentation stating that dm_crypt does not currently support TRIM passthrough, however I also found other sources that state the opposite (albeit for other distributions) and even that discards are not needed for recent SSD drives which use some sort of automatic garbage collection. So: 1) Can I enable TRIM/discards with my setup? 2) Do I need to, for optimal disk performance? Thanks for your thoughts.

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• Linux monitor logs and email alerts?

  - by Physikal

  I have a server with a faulty power button that likes to reboot itself. Usually there are warning signs, like the acpid log file in /var/log starts spamming garbage for about 10hrs or so. Is there an easy way I can have something monitor the acpid log and email me when it has new activity? I wouldn't consider myself extremely advanced so any "guides" you may have for accomplishing something like this would be very helpful and much appreciated. Thank you!

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• DansGuardian: content regexp list for exact sites, how?

  - by Sergey

  We have contentregexplist file where we can write all substitutions like "source regex"-"dest string" And they ALL run for each page. Is it possible somehow to define a domain name(s) for which (only for 1 domain! not every page) some regexps should be looked for? To be clear: How to replace "Google"-"garbage" in page source only for host host.example.org? May be other content filtering system can do this? Then which one?

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• On linux how can make a list of files that are owned by a particular owner and then fix the group and owner?

  - by Stuart Woodward

  I have a deep and complex file system where some files have been accidently written by root. I want to change the ownership of those files back to the original owner in one go. I am playing with commands like: find /folder -type f | xargs ls -l | grep "root root" but there is a lot of garbage coming out too. I want to make a list first and then change only the files in that list after confirmation.

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• Sometimes my files become corrupt while copying to USB

  - by Mirage

  I bought a new USB . Sometimes when i copy paste the files , then i try to run it from USB it gives file is corrupt or archieve is corrupt. WIth text files when i open from USB sometimes some garbage characters appear instead of original text. What can be the reason

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• Software for Automatic Remote FTP Backup

  - by Baez

  I'm looking for software (free or paid) that could perform a weekly automatic backup to an outside server via FTP. I've looked around and all I seem to be finding is either garbage shareware or free tools that are no longer supported. The system will be backing up from a Windows 7 desktop system to a Linux CentOS 5 server. Can someone direct me to a stable, reliable piece of software? This is for business documents so reliability is key.

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