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• ssh-keygen accepting stdin

  - by Ryan

  I am trying to call ssh-keygen using a variable through bash as an input instead of a file to get a fingerprint of a public key. This method does not work as it says the key file is invalid (it's correct for sure) echo $pubkey | ssh-keygen -lf /dev/stdin This does work ssh-keygen -lf /dev/stdin < alpha.pub This does not work because I get an ambiguous redirect ssh-keygen -lf /dev/stdin < $(echo $pubkey) I would appreciate some insight as to how to get ssh-keygen to read from a variable with a public key and if possible, an explanation as to why the redirects aren't doing what I think they should be doing. I searched online but many of the redirect tutorials didn't seem to answer my questions.

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• How to get `gcc` to generate `bts` instruction for x86-64 from standard C?

  - by Norman Ramsey

  Inspired by a recent question, I'd like to know if anyone knows how to get gcc to generate the x86-64 bts instruction (bit test and set) on the Linux x86-64 platforms, without resorting to inline assembly or to nonstandard compiler intrinsics. Related questions: Why doesn't gcc do this for a simple |= operation were the right-hand side has exactly 1 bit set? How to get bts using compiler intrinsics or the asm directive Portability is more important to me than bts, so I won't use and asm directive, and if there's another solution, I prefer not to use compiler instrinsics. EDIT: The C source language does not support atomic operations, so I'm not particularly interested in getting atomic test-and-set (even though that's the original reason for test-and-set to exist in the first place). If I want something atomic I know I have no chance of doing it with standard C source: it has to be an intrinsic, a library function, or inline assembly. (I have implemented atomic operations in compilers that support multiple threads.)

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• Drag-and-drop file upload in Chromium?

  - by Zarel

  Drag-and-drop file uploading can be done in Firefox 3.6 by using FileReader: http://stackoverflow.com/questions/2121018/native-drag-drop-file-upload-in-firefox-3-6 However, Google recently released an update for Gmail that allowed drag-and-drop file uploading in Chromium as well as Firefox, and Chromium does not have FileReader. I'm using the latest Chromium nightly, and it can drag-drop upload files, while not supporting FileReader. I've seen someone mention that drag-drop uploading can be possible by dragging onto an <input type="file" />, but that can only support one file at a time, while Gmail's uploader can handle multiple files being dragged onto it, so that's clearly not what they're doing. So the question is, how do they do it? How do you support Chromium for HTML5 file uploading?

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• posmax: like argmax but gives the position(s) of the element x for which f[x] is maximal

  - by dreeves

  Mathematica has a built-in function ArgMax for functions over infinite domains, based on the standard mathematical definition. The analog for finite domains is a handy utility function. Given a function and a list (call it the domain of the function), return the element(s) of the list that maximize the function. Here's an example of finite argmax in action: http://stackoverflow.com/questions/471029/canonicalize-nfl-team-names/472213#472213 And here's my implementation of it (along with argmin for good measure): (* argmax[f, domain] returns the element of domain for which f of that element is maximal -- breaks ties in favor of first occurrence. *) SetAttributes[{argmax, argmin}, HoldFirst]; argmax[f_, dom_List] := Fold[If[f[#1]>=f[#2], #1, #2]&, First[dom], Rest[dom]] argmin[f_, dom_List] := argmax[-f[#]&, dom] First, is that the most efficient way to implement argmax? What if you want the list of all maximal elements instead of just the first one? Second, how about the related function posmax that, instead of returning the maximal element(s), returns the position(s) of the maximal elements?

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• Why does the release build of my iPhone app crash on the device on the first run after installation?

  - by Chris Cooper

  I have an iPhone app that's been in development for about 2 weeks. We recently tried the "release" version of the build on a device, and to our great unhappiness, it crashes in one of the views with an "EXC_BAD_ACCESS". This crash only occurs on devices, and only in the "release" build. Not only that, but it only happens the first time the app is launched! It is also 100% reproducible. We have removed the small block of code that deals with data persistence, and have tried re-openning Xcode, cleaning the project, deleting and reinstalling the app, etc., as some other questions suggest. Do you have any advice for a) what might be causing this problem, and b) how to go about debugging if it only happens in "release"? Thanks

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• Examining mmaped addresses using GDB

  - by Mikeage

  I'm using the driver I posted at http://stackoverflow.com/questions/647783/direct-memory-access-in-linux/ to mmap some physical ram into a userspace address. However, I can't use GDB to look at any of the address; i.e., x 0x12345678 (where 0x12345678 is the return value of mmap) fails with an error "Cannot access memory at address 0x12345678". Is there any way to tell GDB that this memory can be viewed? Alternatively, is there something different I can do in the mmap (either the call or the implementation of foo_mmap there) that will allow it to access this memory? Note that I'm not asking about /dev/mem (as in the first snippet there) but amount a mmap to memory acquired via ioremap(), virt_to_phys() and remap_pfn_range()

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• shutdown windows 8 from metro app

  - by MindFreak

  I'm doing a metro app for Windows 8. And as part of its functionality, I need to initiate shutdown of Winodws 8 from the Metro App. Here are the questions: 1) Firstly, I researched a lot on this topic and I found out that System.Diagnostics.Process is not available for Metro App. So, is there a another way around? 2) Even if I can't directly shutdown, is there a way to trigger it from the Metro App? I would prefer a solution in C#. Thanks.

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• Customizing the behavior of ControlDesigners for Controls derived from native .NET controls.

  - by Eric

  My question is related to this question: http://stackoverflow.com/questions/93541/baseline-snaplines-in-custom-winforms-controls However, in my case, I have created a new control that derives from TextBox rather than containing a TextBox. I would like to have a custom ControlDesigner, but I would like to modify the behavior of the TextBox's designer rather than having to write a complete designer myself. In particular, I'd like to be able to return the TextBox's SnapLines while providing some custom verbs. Is there a good way to do this? EDIT: To clarify, this is for Windows Forms in .NET 2.0.

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• How are binding specified for Interface Builder plugins?

  - by Benedict Cohen

  I'm creating an Interface Builder plugin for an NSView subclass. I've been following the Interface Builder Plug-in Programming Guide but it's not answer all my questions. My class has one NSString property and 4 NSColor properties which I want to create bindings for at design time. I can't figure out where the bindings are specified in the plugin project. The documentation states that the Inspector Object is only for creating the Attribute Inspector. The class description file (.classdescription) lists outlets and actions but not bindings. Where do I specify the bindings for my class?

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• How to Prove that using subselect queries in SQL is killing performance of server

  - by adopilot

  One of my jobs it to maintain our database, usually we have troubles with lack of performance while getting reports and working whit that base. When I start looking at queries which our ERP sending to database I see a lot of totally needlessly subselect queries inside main queries. As I am not member of developers which is creator of program we using, they do not like much when I criticize they code and job. Let say they do not taking my review as serious statements. So I asking you few questions about subselect in SQL Does subselect is taking a lot of more time then left outer joins? Does exists any blog, article or anything where I subselect is recommended not to use ? How I can prove that if we avoid subselesct in query that query is going to be faster ? Our database server is MSSQL2005

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• iPad book / cartoon contents plus Marvel like cartoons

  - by anthony

  Hi, I want to create and sell book / cartoons by individual episodes. What's the best way to to this? iBook from the apple store tends to sell by entire volume / book... I see an App from Marvel sells its contents by individual episodes, but I don't want to create / maintain shopping carts and stuff. (I am assuming iPad / iPhone users are downloading each cartoon episodes by their Marvel servers) I want to utilize Apple iBook / iTune store... Second questions: Is Marvel-like cartoons all jpg pictures showing frame by frame? Thanks in advance!!!

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• Is this a well known design pattern? what is it's name

  - by GenEric35

  Hi I have seen this often in code, but when I speak of it i don't know the name of such 'pattern' I have a method with 2 arguments that calls an overloaded method that has 3 arguments and intentionality sets the 3rd one to empty string. public DoWork(string name, string phoneNumber) { CreateContact(name, phoneNumber, string.Empty) } public DoWork(string name, string phoneNumber, string emailAddress) { //do the work } The reason I'm doing this is I to not duplicate code, and allow the existing callers to still call the method that has only 2 parameters. I have associate a few tags to this question, but it probably fit in more categories of questions. Is this a pattern, and does it have a name?

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• Saving current directory to zsh history

  - by user130208

  I wanted to achieve the same as asked here http://stackoverflow.com/questions/945288/saving-current-directory-to-bash-history but within zsh shell. I haven't done any zsh trickry before but so far I have: function precmd { hpwd=$history[$((HISTCMD-1))] if [[ $hpwd == "cd" ]]; then cwd=$OLDPWD else cwd=$PWD fi hpwd="${hpwd% ### *} ### $cwd" echo "$hpwd" ~/.hist_log } Right now I save the command annotated with the directory name to a log file. This works fine for me. Just thought there might be a way to make replacement in the history buffer itself.

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• Hudson, C++ and UnitTest++

  - by Gilad Naor

  Has anyone used Hudson as a Continuous-Integration server for a C++ project using UnitTest++ as a testing library? How exactly did you set it up? I know there have been several questions on Continuous Integration before, but I hope this one has a narrower scope. EDIT: I'll clarify a bit on what I'm looking for. I already have the build set to fail when the Unit-Tests fail. I'm looking for something like Hudson's JUnit support. UnitTest++ can create XML reports (See here). So, perhaps if someone knows how to translate these reports to be JUnit compatible, Hudson will know how to eat it up?

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• Attaching events in JavaScript

  - by R0MANARMY

  As comment to one of the questions here a commenter wrote (emphasis mine): ... By using an inline "onclick" you are doing a similar thing, but it is harder to maintain and more prone to issues. The JavaScript community as a whole has been moving away from inline JavaScript for a while now. This was referring to attaching events to HTML elements using $("#someID").click(function(){ do something here...; }); rather than <a id="someID" onclick="someFunction();"> Has there really been a shift away from the old school way of declaring events inline, and if so, what are the benefits of one of the other?

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• Php PEAR, Database Abstraction & Factory Methods

  - by pws5068

  I'm interested in learning more about design practices in PHP for Database Abstraction & Factory methods. For background, my site is a special-interest social networking community currently in beta mode. Currently, I've started moving my old code for object retrieval to factory methods. However, I do feel like I'm limiting myself by keeping a lot of SQL table names and structure separated in each function/method. Questions: 1.) Is there a reason to use PEAR (or similar) if I dont anticipate switching databases? 2.) Can PEAR interface with the MySqli prepared statements I currently use? 3.) Will it help me separate table names from each method? (If no, what other design patterns might I want to research?) 4.) Will it slow down my site once I have a significantly large member base?

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• Expression Tree : C#

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• JSF implementations and component libraries

  - by Avinash Nandagiri

  I have just started using JSF and I have three questions related to JSF implementations and component libraries What is the difference between JSF Implementations and Component Libraries? What are the various JSF implementations (like Apache MyFaces) that are available and what is the difference between each one of them? What are the various JSF component libraries (like rich faces and ice faces) that are available and what is the difference between each one of them? Any relevant links giving the exact information on this would also be helpful. Thanks a lot in advance.

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• Why does the data binding in this validation example work?

  - by MartyIX

  I'm wondering how exactly the XAML sample (MSDN sample) works: <Style x:Key="textBoxInError" TargetType="{x:Type TextBox}"> <Style.Triggers> <Trigger Property="Validation.HasError" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/> </Trigger> </Style.Triggers> </Style> Questions: (Validation.Errors)[0].ErrorContent - Is this code somehow checked by WPF? Because Validation.Errors may be an empty collection and in ordinary C# code this code may throw an exception. If this data-binding returns null for valid input - the null value is then casted to empty string (in a text control for example)? The index 0 corresponds to the first error message. How can I return more error messages from Validate method? Thank you for responses!

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• How can I build a Truth Table Generator?

  - by KingNestor

  I'm looking to write a Truth Table Generator as a personal project. There are several web-based online ones here and here. (Example screenshot of an existing Truth Table Generator) I have the following questions: How should I go about parsing expressions like: ((P = Q) & (Q = R)) = (P = R) Should I use a parser generator like ANTLr or YACC, or use straight regular expressions? Once I have the expression parsed, how should I go about generating the truth table? Each section of the expression needs to be divided up into its smallest components and re-built from the left side of the table to the right. How would I evaluate something like that? Can anyone provide me with tips concerning the parsing of these arbitrary expressions and eventually evaluating the parsed expression?

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• Some help with basic Sound functions in actionscript 3

  - by danwoods

  Hello all. I'm working on a mp3 player and I'm super new at all things flash so there are lots of questions. Currently I'm getting stuck on the track change. My variable declaration look like this: var index:int = -1; var music:Sound = new Sound(new URLRequest("moe2008-05-24d02t02_vbr.mp3")); var sc:SoundChannel; var isPlaying:Boolean = false; and my change track function looks like this: function changeTrack(newTrack){ sc.stop(); isPlaying = false; music = new Sound(new URLRequest(newTrack)); sc = music.play(); isPlaying = true; index++; } Does anyone see any obvious errors??? Thanks

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• Some doubts in WPF

  - by xyz

  I am entirely new to WPF . Though I am going thru the tutorials and articles from net but I am having doubts . Some of the questions which have striked out so far are a) What is routed events and what extra thing it does server? b) What are dependency properties and it's benefits. c) How dependency properties differ from attached properties. d) Why does first bubbling happens follwed by tunneling? And what is the purpose of this? e.g. <canvas> <button canvas.left=10/> </canvas> Is it a dependency property or attached property? Thanks

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• How do I design a cryptographic hash function?

  - by Eyal

  After reading the following about why one-way hash functions are one-way, I would like to know how to design a hash function. http://stackoverflow.com/questions/1038307/help-me-better-understand-cryptographic-hash-functions/1047106#1047106 Before everyone gets on my case: Yes, I know that it's a bad idea to not use a proven and tested hash function. I would still like to know how it's done. I'm familiar with Feistel-network ciphers but those are necessarily reversible, horrible for a cryptographic hash. Is there some sort of construction that is well-used in cryptographic hashing? Something that makes it very one-way?

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• How events are assigned in .NET

  - by Matt

  I just realized I didn't fully understand why in .NET you assign events using a += symbol. I figured this out yesterday when I needed to remove an event and without thinking I was doing someobject.onsomeevent += null thinking that would just remove the event I had previously assigned. After some investigation, I figured out I had to someobject.onsomeevent -= someeventmethod; After figuring this out, I realized I don't understand how event methods are assigned in .NET. So I have a few questions: First, does it mean that I can do someobject.onsomeevent += someeventmethod; someobject.onsomeevent += someeventothermethod; If so, when onsomeevent occurs will they both get hit, and in the order specified or simultaneously? Furthermore, how can I determine what event methods are already assigned to someobject.onsomeevent? Second, is there a way to save the events methods in some class, remove them from someobject.onsomeevent and re-assign them after some other procedures that would normally trigger the event are complete?

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• Geocode multiple addresses

  - by ace2600

  I need to geocode around 200 addresses per request and do around 3,000 request per day. I will be doing this server side using PHP. I have looked at http://stackoverflow.com/questions/98449/how-to-convert-an-address-to-a-latlon, but could not find a way for either Google Maps HTTP Request API or the Yahoo Geocoding REST API (cannot use JavaScript as this is server side) to send multiple addresses. I will be primarily using this to sort addresses based on the coordinates and if the API supports, fill in any missing data for each address. The addresses will be in the United States only. The addresses to geocode will be from user input, so be free form, like "street address, postal code", or "city, state", etc. Accuracy is not too important for the coordinates, say within five hundred feet or so. Is there a free API to handle this? Is there a way to get Yahoo or Google to do multiple locations in a request?

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