It is possible to have Steam Family Sharing set up so me and my child can both play the same game at the same time? As of now it says:     An error occurred while updating Red Faction Guerilla Steam Edition (shared library locked)   Is there a possible fix or am I stuck with it?

My brother owns Skyrim on steam. We use Steam Family Share, but we were wondering how both of us could play it at the same time?


Sorry for that beginner Q. If I upgrade my  Ubuntu from 18.04.5 LTS to 20.04.1 LTS it will erase my personal files and installed software? something else, I see there some problems with others after upgrading, it is right to upgrade now? what are the criteria that I decide to upgrade based on? Thank You,,

What are the different ways I can use to upgrade Ubuntu from one release to another?


I am taking a Linux course and am confused by the user restrictions I found in one lab.  The lab is to change the maximum number of PIDs, verify the change, and then put it back to normal.  The lab offers two different ways to do this: 1) echoing the value into /proc/sys/kernel/pid_max, and 2) using sysctl to change the value.  What I am not able to determine is why the echo has to be executed as root and the sysctl can use sudo. Thank you, in advance, for an answer. Here is a copy of my bash window as examples: me@localhost:~$ cat /proc/sys/kernel/pid_max 32768 me@localhost:~$ sudo echo 2400 > /proc/sys/kernel/pid_max bash: /proc/sys/kernel/pid_max: Permission denied me@localhost:~$ sudo sysctl kernel.pid_max=2400 [sudo] password for me: kernel.pid_max = 2400 me@localhost:~$ cat /proc/sys/kernel/pid_max 2400 me@localhost:~$ su Password: root@localhost:/home/me# echo 32768 > /proc/sys/kernel/pid_max root@localhost:/home/punko# exit exit me@localhost:~$ cat /proc/sys/kernel/pid_max 32768

Possible Duplicate:          Running a command like sudo echo 'text' >> /file.txt fails with:  bash: /file.txt: Permission denied


I have a domain hosted at Bluehost.com, and email forwards are not making it to aol.com users. DNS and MX records are configured per Bluehost's instructions.   Bluehost has assigned me an IP Address. I have an A record email.[domain].com pointing to the assigned IP address.   Forwarding works to other domains.

This is a  about how to handle email sent from your server being misclassified as spam.  For additional information you may find these similar questions helpful:                    Sometimes I want to send newsletters to my customers. The problem is, that some of the emails get caught as spam messages. Mostly by Outlook at the client (even in my own Outlook 2007).  Now I want to know what should be done to create "good" emails. I know about reverse lookup etc., but (for example), what about a unsubscribe link with an unique ID?  Does that increase a spam rating?


Schrödinger's equation is supposed to be a differential equation for the wave function of a particle. As I currently understand, De Broglie's hypothesis is a hypothesis that for particles there should be some wave function $\Psi$ with wavelength $\lambda$ such that  $$p=\dfrac{h}{\lambda}$$  Where $p$ is the particle's momentum and $h$ is Planck's constant. As I understand, this hypothesis is based on the following: for light, we know there is a wave function, but we also know that it has particle behavior and we know that $p = h/\lambda$ holds, in that case we want the converse for particles.  The hypothesis, however, doesn't tell which differential equation this wave function satisfies. In that case, Schrödinger's equation is the answer to that, saying that the differential equation is  $$i\hbar \dfrac{\partial \Psi}{\partial t}=\left(-\dfrac{\hbar}{2m}\nabla^2+V\right)\Psi$$  Now, I simply can't understand why it would be reasonable to consider that equation. I mean, if we just accept it and deduce results, then we get a feeling that it should be right. But how could one motivate it? I mean, what reasoning lead Schrödinger to that equation in specific?  Is it possible, without knowing further quantum mechanics that follows from the equation, to motivate that the wave function of a particle should satisfy that equation? I've heard that this equation can't be derived. But I believe there is some reasoning behind it.

I am aware of the debate on whether Schrödinger equation was derived or motivated. However, I have not seen this one that I describe below. Wonder if it could be relevant. If not historically but for educational purposes when introducing the equation.   Suppose that we have the time dependent Schrödinger equation for a free particle, $V=0$.   $$-\frac {\hbar i}{2m} \nabla^2 \Psi_\beta = \frac {\partial \Psi_{\beta}}{\partial t} $$  As the particle moves its heat is diffused throughout space. Now consider that we consider Heat equation or in general Diffusion equation:  $$\alpha\nabla^2 u= \frac {\partial u}{\partial t} $$  Where $u$ is temperature.   Also we have particle diffusion equation due to Fick's second law.  $$D \frac {\partial^2 \phi}{\partial x^2}= \frac {\partial \phi}{\partial t} $$  Where $\phi$ is concentration.  Furthermore, probability density function obeys Diffusion equation. So as the free particle moves, the heat, the temperature, or the density is diffused.   Now we can motivate Schrödinger equation in an intuitive way. Mathematically it is describing the same diffusion.  Am I right? Have you seen more like this motivation elsewhere?


When people explain Theta notation, they just start talking about a function T(n) without explaining what it is. Is it just a given function?  Why is it Theta(f(n)) instead of Theta(n)? Where did the f(n) come from? f(n) is usually a given function, then what is T(n)? Are they both? This is also not commonly explained.   All the explanations I find are all explained mathematically, but with consistent failure properly define things, and instead just start talking about things out of the blue.  Thanks,  - A confused student

Sometimes I see Θ(n) with the strange Θ symbol with something in the middle of it, and sometimes just O(n). Is it just laziness of typing because nobody knows how to type this symbol, or does it mean something different?


How do we evaluate $\displaystyle\int_{0}^\pi \dfrac {\sin^2 x}{a^2-2ab \cos x + b^2}\mathrm dx$ ? I tried substitution and some other methods , but its not working ; please help .

Calculate the definite integral      $$ I=\int_0^{\pi} \frac{\sin^2 x}{a^2+b^2-2ab \cos x}\;\mathrm dx $$      given that $a>b>0$.   My Attempt:  If we replace $x$ by $C$, then  $$ I = \int_{0}^{\pi}\frac{\sin^2 C}{a^2+b^2-2ab\cos C}\;\mathrm dC $$  Now we can use the Cosine Formula ($A+B+C=\pi$). Applying the formula gives  $$ \begin{align} \cos C &= \frac{a^2+b^2-c^2}{2ab}\\ a^2+b^2-2ab\cos C &= c^2 \end{align} $$  From here we can use the formula $\dfrac{\sin A}{a} = \dfrac{\sin B}{b} = \dfrac{\sin C}{c}$ to transform the integral to  $$ \begin{align} I &= \int_{0}^{\pi}\frac{\sin^2 C}{c^2}\;\mathrm dC\\ &= \int_{0}^{\pi}\frac{\sin^2A}{a^2}\;\mathrm dC\\ &= \int_{0}^{\pi}\frac{\sin^2 B}{b^2}\;\mathrm dC \end{align} $$  Is my process right? If not, how can I calculate the above integral?


So I know that when you put some charge inside a counter, it resides uniformly on the surface of the conductor in order to make the electric field zero everywhere inside the conductor..  But what if I place a charge in such a way that I make it stationary inside the conductor (let it be a spherical conductor), will there be an electric field inside coming out of the charge (assuming its positive) or will something happen to prevent it? And if something happens to prevent it can you please explain to me the process of how it works  The spherical conductor is hollow and the charge I put inside it (let's say its in a random place other than the center) is stationary

I know that the $E$ field inside a conductor is zero. What happens if I put a source of charge inside the conductor?  Say the conductor was spherical centered on the origin and there exists a charge at the origin.  Then by Gauss's Law, there exists a non zero field inside the conductor.  Or is it the case that even though this charge is within the sphere, it will redistribute evenly over the surface and hence the E field inside is zero?


I'm trying to find a simple solution to monitor all desktop machines of my network (~ 35 Ubuntu desktop). I do not want to use passive monitoring like Munin or Cacti but with an active agent on the desktop, i wish only keep a day or a week of data retention i do not need more.  In fact i plan to use New Relic Server to monitor as my servers. Is there a best way ?

For a more comprehensive list of monitoring tools and their features, check out .   As the question states, what are the most commonly used tools used for this task and what are their strengths and weaknesses?


I am looking for a markdown editor for mac os x. There seems to be so many around.  Ideally one that is compatible with github MD  Anybody can recommend one that allows preview, and with really good functionality and kept up to date and frequent updates.  Its not important if its pay or free..  Thanks in advance  The question being presented as a duplicate, is out of date, the program they suggest hasn't been updated for a while.

Are there any editors or notes applications out there that support Markdown?   I am often having to make notes or documents where markdown formatting would be ideal, and have gotten into the habit of using markdown on a daily basis.


I was thinking of using thin clients with PXE booting, using a Windows virtual disk image and CCBoot in Wine on Linux. Even though it is a single Windows image, it may be distrubuted to many clients. With this in mind, what are the Windows licensing requirements for this setup?  As opposed to the possible duplicate this question specifically asks for licensing requirements of PXE boot images. Also the solution to the possible duplicate does not answer my question.

This is a  about Licensing.    Questions on licensing are off-topic on Server Fault.  If your question has been closed as a duplicate of this question, then this is because we want to help you understand why licence questions are off topic rather than just telling you "it just is". In all likelihood, this question will not address your question directly, it was not meant to.    I have a question regarding software licensing. Can the Server Fault community please help with the following:   How many licenses do I need? Is this licensing configuration valid? What CALs do I need to be properly licensed? Can I run this product in a virtual environment? Can I downgrade this product to an earlier version? Am I entitled to feature X with license Y?


I use minted for syntax highlighting  If I give it this C code  int foo () {    return 123; }  int bar () {     int x = foo ();     ++x; }   it will colour-highlight foo in the first line, but later when foo is called in the body of bar, it will not be coloured.  How can I add foo to minted's dictionary so that it will be highlighted everywhere that it appears? Similarly, how can I add the variable x to the dictionary so that it will be highlighted in the line ++x?  The minimum requirement is that all minted usages (\begin{minted} or \inputminted) will use the same dictionary of function/variable names (per language).  Ideally, code such as \definecfunction{foo} could appear anywhere in the document (repeatedly), and all minted usages everywhere would pick it up (presumably this would be a two-pass process). Non-ideally, a full list of symbols could be provided in advance.  How can I make this happen?

I have defined several structures and types in a C++ project. I have to write some documentation for this code, and I use  to typeset my code.   I would like to be able to add some keywords to the minted database, so minted will also recognize these and give them the appropriate color. (I would like to have them colored in the same way a type, eg. double would be colored.)


When I write comments to users with a name that does not contain a space I can type:  @Part   And then I would be offered to complete the whole name.  For example if I answer Martin, I can just type:  @Mart   However, if the user name contains spaces like Martin The Great this wont work, and the system will swallow my @Martin The Great in the comment body.   Does anyone know how to overcome this little annoyance?

How do the comment replies (aka "pinging users") work?  Who can I send an @reply to? How do I respond to a specific user when entering my comment? Will they be notified? What do people mean when they talk about "pinging" another user?  Related:


The visits and views on Stack Overflow have vanished before January 2018.   What's happened to them? Are we going to have them restored?

There was a previous bug affecting site traffic statistics showing -zero- for months (). This has been fixed in that it is now graphing the data.  It appears that previous data may be lost? The graphs below are from . I don't have access to any other sites' graphs to see if they are showing similar results.


I had to solve: $z^2 + 1 - i = 0$. What I did:  $$z_{1, 2} \frac{-0 \pm \sqrt{0 - 4(1 - i)}}{2} = \pm \sqrt{i - 1}$$  Now, I need to find $\Im(z_{1, 2})$ and $\Re(z_{1,2})$.  I think there is a way to solve it using the trigonometric representation, right? I somehow didn't found what I wanted so I'd love if someone can just tell me what I should look up. I'm okay with you people just giving me the proper term to google. :)  Thanks

If I'm given a complex number (say $9 + 4i$), how do I calculate its square root?


Let $f$ be a continuous function at $x_0$ and differentiable in the neighborhood of $x_0$. If $\lim_{x\to x_0}f'(x)$ exists, then $f$ differentiable at $x_0$ and $f'(x_0)=\lim_{x\to x_0} f'(x)$. It might be a classic result, but I didn't really find the post here using MVT. If someone could give a feedback on my proof, I would really appreciate it. Thank you in advance.  First of all, as $f$ is differentiable in the neighborhood of $x_0$, then there exists $\delta>0$ such that $f$ is differentiable on $]x_0-\delta,x_0+\delta[$. Consider an interval $[x_0, x]$ with $x \in ]x_0,x_0+\delta[$. $f$ is continuous on $[x_0,x]$ (because differentiable in the neighborhood of $x_0$ and continuous at $x_0$) and differentiable on $]x_0,x[$. Let  $\lim_{x\to x_0}f'(x)=L\in \mathbb{R}$ Then, by MVT, $\exists c_x \in ]x_0,x[$: $f(c_x)=\frac{f(x)-f(x_0)}{x-x_0}$ $\implies$ $\lim_{x\to x_0}f'(c_x)=L=\lim_{x\to x_0}\frac{f(x)-f(x_0)}{x-x_0}=f'(x_0)$ as wanted. So,   $f$ differentiable at $x_0$ and $f'(x_0)=\lim_{x\to x_0}f'(x)$. I'm not really sure about my definition $x$ (it's domain). I think that it is not well defined. I could have passed by another definition of derivative and use the limit as $\delta\to 0 $, but I didn't really find how to define correctly my interval.

Let $f$ be a real-valued function continuous on $[a,b]$ and differentiable on $(a,b)$. Suppose that $\lim_{x\rightarrow a}f'(x)$ exists. Then, prove that $f$ is differentiable at $a$ and $f'(a)=\lim_{x\rightarrow a}f'(x)$.    It seems like an easy example, but a little bit tricky. I'm not sure which theorems should be used in here.    ==============================================================  Using @David Mitra's advice and @Pete L. Clark's notes I tried to solve this proof. I want to know my proof is correct or not.  By MVT, for $h>0$ and $c_h \in (a,a+h)$ $$\frac{f(a+h)-f(a)}{h}=f'(c_h)$$ and $\lim_{h \rightarrow 0^+}c_h=a$.    Then $$\lim_{h \rightarrow 0^+}\frac{f(a+h)-f(a)}{h}=\lim_{h \rightarrow 0^+}f'(c_h)=\lim_{h \rightarrow 0^+}f'(a)$$   But that's enough? I think I should show something more, but don't know what it is.


I'm trying to remember the author and title of a book I read 30 years ago or so, about a race of insectoid aliens and their journey from pre-space-age, to being able to travel between the stars. Kind of a Foundation-scale scope, but just a single book. The perspective jumps by generations throughout the history of this civilization.  I thought it was Brin, or Saberhagen, or Pohl, but I've not been able to find the book listed in any of their bibliographies.  Ring any bells?

I'm looking for the title of a SF novel that follows an alien civilization through technological eras as it tries to find a way to prevent the destruction of its sun. I believe the novel was published in the 1970s or 1980s. It was written in English and released as a mass market paperback.  The novel opens in the medieval technology era. The first protagonist is an astronomer whose observations of the sky cause him to realize their home solar system is in cosmological peril. (Sorry, I can't remember the specific cause of the impending doom.) The astronomer must now convince everyone of the gravity of the situation, a task made difficult by the religious institutions and political conflicts of the world.  Once the alien civilization realizes the seriousness of the problem, the novel shifts to a race against time, through technological eras, as its scientists work to find a way to save themselves from destruction.  A unique aspect of the alien civilization is that it is very biology-focused. Where humanity would have fabricated something out of metal, this civilization's technology harnesses biological engineering (selective breeding, genetic engineering, etc) to accomplish the same task.  I hope this is enough information to jog someone's memory!


How do I copy and paste a long command from a website into a command block?

If you have copied a zombie herobrine command what do you press on your computer to put the command in the command block?


I accidentally restored BIOS on my dell Inspiron 5559 which was dual booting earlier with Windows 10 and Ubuntu-16.04. After restoring BIOS, GRUB got deleted which I repaired using boot-repair. I restarted the system and GRUB successfully loaded. I wanted to make sure that windows was okay, so I booted into Windows.   The problem arose when I restarted from Windows. GRUB was nowhere to be seen after restarting from Windows.

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


$$\lim_{x\to 1}\frac9{1-x^9}-\frac7{1-x^7}$$  I did this with l'Hôpital's rule, but how can we do this problem other than that? Any hints will be good.

Find $\lim_{x\to 1}(\frac{p}{1-x^p}-\frac{q}{1-x^q})$    My attempt: I took LCM and applied lhospital but not getting the answer.Please help


Of course, since the cardinality of $\mathbb{R}$ exceeds the cardinality of $\mathbb{Q}$, there does not exist a bijection between $\mathbb{Q}^\ast$ and $\mathbb{R}^\ast$, let alone a group isomorphism.  My question is whether it is also possible to prove that these multiplicative groups are not isomorphic without using a cardinality argument.

Does there exist any surjective group homomorphism from $(\mathbb R^* , .)$ (the multiplicative group of non-zero real numbers) onto $(\mathbb Q^* , .)$ (the multiplicative group of non-zero rational numbers)?


[First this question may be taking about same concept as , but has different context.]  I came across  which states:     In JavaScript, each object has a property called “prototype”. An   object’s prototype allows us adding properties to all instances of   that object (even to the existing instances).   As per my understanding so far, the above statement is confusing for beginners as it does not distinguish between "prototype" and "[[Prototype]]". Not all objects have a prototype property, for example:  var myobject = {}; myobject.prototype; // Undefined   I think it would be better if we say:     In JavaScript, each object has an internal property called   “[[Prototype]]” that can be seen in some browsers by accessing the   non-standard property called “__proto__”.  An object’s prototype   allows us adding properties to all instances of that object (even to   the existing instances). Only functions (hence constructors) have   ‘prototype’ property to set that allows us adding properties to all   instances of that object made by that function/constructor.   Is this a more accurate description of JavaScript prototypes, or am I missing something? Thanks in advance.

I'm not that into dynamic programming languages but I've written my fair share of JavaScript code. I never really got my head around this prototype-based programming, does any one know how this works? var obj = new Object(); obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test();  I remember a lot discussion I had with people a while back (I'm not exactly sure what I'm doing) but as I understand it, there's no concept of a class. It's just an object, and instances of those objects are clones of the original, right? But what is the exact purpose of this ".prototype" property in JavaScript? How does it relate to instantiating objects? Update: correct way var obj = new Object(); // not a functional object obj.prototype.test = function() { alert('Hello?'); }; // this is wrong!  function MyObject() {} // a first class functional object MyObject.prototype.test = function() { alert('OK'); } // OK  Also these  really helped a lot.


The late Mr Lee Kuan Yew has been hailed by many as "Singapore's Chief Gardener" for his vision and single-minded commitment to transforming our country into a lush garden city and creating the best possible living environment for all citizens to enjoy.   I have tried referring to these links but to no avail:     This link only explains about want to see you which is helpful, and the "look forward to seeing you" is common on Internet. But both explanations are specific to the said grammatical instances only, not general.   This link only explains about look forward to hearing, which is again specific and special grammatical instance.   This link mentions transitivising particle, but without elaboration and lacks citation.   No matter how much I try to use inductive reasoning, I can't figure out why using "...to transform our country..." is wrong.

I saw some scenarios that used the structure "to + V-ing", such as the following:   Looking forward to hearing. Disposed to using few words. I would like to apply what I learned in school to helping make more money. This is the closest we have come to winning the league.   When can I use this structure? I'm confused about that.


I am trying to create a sorted list of lists. Where the outer "layer" is sorted  by the field BU. and the inner layer is sorted by JobNum. I have this method, and variables.  public List<string> ListSorter<T>(IEnumerable<T> records)where T :  IMapToCSVSource, new()  List<IEnumerable<T>> organizedRecords = new List<IEnumerable<T>>(); List<T> shortenedRecord = new List<T>();   Here I am trying to create a more concise object with only 3 specific fields instead of the possible 8 that comes with the records object. BU and JobNum are set within this method.           foreach (var record in records) {     string businessUnit = "foo"; //This would vary each loop, not constant as displayed     string JobNum = "test"       //this would vary each loop, not constant as displayed     shortenedRecord.Add(new T()     {         Cost = record.Cost,         BU = businessUnit,         JobNum = jobNum     }); } shortenedRecord.OrderBy(o => o.BU).ThenBy(n=>n.JobNum);   here, to my knowledge, now has all the records shortened and ordered by BU, then JobNum.  Now I want to parse this ordered list into sections of BU specific records and add it to organizedRecords. Such that each element of organizedRecords is a specific BU. Moving forward how would I do this?  For example, say shortenedRecord is a list of 30 elements, but there is only a total of 5 unique BU values. I would like to order and split the list into their 5 respective BU values, and add it to organizedRecords. Thank you for any suggestions.

I have two tables, movies and categories, and I get an ordered list by categoryID first and then by Name.  The movie table has three columns ID, Name and CategoryID. The category table has two columns ID and Name.  I tried something like the following, but it didn't work.  var movies = _db.Movies.OrderBy( m => { m.CategoryID, m.Name })


I have a source tree with git and I need to reverse all my changes that I have done since September, I know the id of the commit, and I can also generate a list of commits that I want to revert with git rev-list, the question is how do I feed that list to git so that it uncommits all of them?  Or if there is a better way to do this I would really appreciate it.

I would like to remove selected commit log entries from a linear commit tree, so that the entries do not show in the commit log.  My commit tree looks something like:  R--A--B--C--D--E--HEAD   I would like to remove the B and C entries so that they do not show in the commit log, but changes from A to D should be preserved. Maybe by introducing a single commit, so that B and C become BC and the tree looks like.  R--A--BC--D--E--HEAD   Or, ideally, after A comes D directly. D' representing changes from A to B, B to C and C to D.  R--A--D'--E--HEAD   Is this possible? if yes, how?  This is a fairly new project so has no branches as of now, hence no merges as well.


Is there a mathematical way to reverse digits of an integer mathematically? for example:  $18539 \rightarrow 93581$

I was able to work out the cases for $n$ having up to $4$ digits and was wondering if someone could verify my generalization to $m$ digits.  Here I am assuming that when a reversal results in there being a leading $0$ it get ignored (e.g. $76130$ gets reversed to $3167$, $998700$ to $7899$ etc.)  I believe the function can be expressed as $r(n): \mathbb{N} \rightarrow \mathbb{N}$  $$r(n) = \left \lfloor \frac{n}{10^m}\right \rfloor +\sum_{k=0}^{m-1}10^{m-k} \left( \left \lfloor\frac{n}{10^k} \right \rfloor-10 \left \lfloor \frac{\left \lfloor \frac{n}{10^k}\right \rfloor}{10}\right \rfloor \right)$$  where again, $n$ has $m$ digits.  It seems like this combination of the floor function and powers of 10 is the only way to achieve this but is this true?


I tried to install Tex Live on Ubuntu, but I'm stuck. I installed the "install-tl" folder on to my computer and I ran "perl install-tl" on the terminal in the correct directory and waited for all the packages to install. But now, It's asking me to create Paths and create what I assume is a folder and I have no what to do I even checked the website, but now I'm even more confused. All help is greatly appreciated! Edit: I also have TeXStudio installed as someone had told me that I also needed that. This is the message that appeared at the bottom of the terminal after installation was complete:  Welcome to TeX Live! See /usr/local/texlive/2020/index.html for links to documentation. The TeX Live web site () contains any updates and corrections. TeX Live is a joint project of the TeX user groups around the world; please consider supporting it by joining the group best for you. The list of groups is available on the web at . Add /usr/local/texlive/2020/texmf-dist/doc/man to MANPATH. Add /usr/local/texlive/2020/texmf-dist/doc/info to INFOPATH. Most importantly, add /usr/local/texlive/2020/bin/x86_64-linux to your PATH for current and future sessions. Logfile: /usr/local/texlive/2020/install-tl.log

Debian and Ubuntu have very good texlive packaging. But I'd like to use tlmgr to have a more fine-grained control about upgrades and which packages I want to be installed.   So how do I install "vanilla" TeXLive on Debian/Ubuntu?   Also how do I make dpkg aware that I have TeXLive installed?


If I can, I will avoid using the GUI to get around my system, and recently what I have found very annoying is that I seem unable to view the contents and open the contents of a compressed file without decompressing like the GUI application Achieve manager seems to manage to do, although I suspect that it temporarily decompresses the contents of the compressed file into another location and then allows you to browse the contents of the compressed file without having to decompress the contents first into the directory that you are in.  So what I am wondering is if there is any way that I can in Terminal view the contents of a compressed file without actually having to decompress it into a location myself (so that I can get a Terminal view of what Achieve manager does without having to launch a GUI)?

I want to see the contents (list of files and folders) of an archive, for example a  tar.gz file without extracting it.  Are there any methods for doing that?


Note: I have ran the program in IntelliJ without error, I need to make it independent of IDE, i.e. run it under command line. I got the error not because I didn't implement it, but I didn't understand how I can let compiler know it.  I have a project composed of 7 to 10 java files, relies on 5 jar files. The project is managed in IntelliJ project, version 2017.1.  Now I want to run a java class with a main function from the project. In the command line of local computer, I run the class with script:  /project/out/path> java retrieve_result   I correct my script as .  Note: in the retrieve_result class, there are dependencies on other java and jar files.   The error is shown as below:  Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/lucene/store/Directory         at HW2MainLucene.ReadIndex(HW2MainLucene.java:69)         at HW2MainLucene.main(HW2MainLucene.java:23) Caused by: java.lang.ClassNotFoundException: org.apache.lucene.store.Directory         at jdk.internal.loader.BuiltinClassLoader.loadClass(java.base@9-internal/BuiltinClassLoader.java:366)         at jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(java.base@9-internal/ClassLoaders.java:184)         at java.lang.ClassLoader.loadClass(java.base@9-internal/ClassLoader.java:419)         ... 2 more   As far as I have learned, this error comes because the compiler cannot locate the jar files. But in the IntelliJ project, it is already configured.  How can I configure the compiler to get a usable program?

I am getting a NoClassDefFoundError when I run my Java application.  What is typically the cause of this?


When i ping 8.8.8.8 from my home computer (europe) i get around 26 ms latency. When i ping 8.8.8.8 from a server(US) i get around 1 ms latency. When i ping my (US) server from home (europe) i have 130 ms latency.   I know that i can setup a custom DNS/nameservers and attach it to my domain so it can be used to geographically resolve domain names / route traffic to the closest server/loadbalancer.    However, as my experiment above showed apparently something similar is possible with ip's?  Can someone explain to me how this works / how i can replicate it?

I'd never heard of anycast until a few seconds ago when I read "".  The wikipedia "" article on it is quite formal and doesn't really evoke a mental picture of how it would be used.  Can someone explain in a few informal sentences what "anycast" is, how you configure it (just in a general sense), and what its benefits are (what does it make easier)?


All sites give this value as "exact" value. I mean, what's after the comma? 299792458,000 m/s?

I could understand that the definition of a second wouldn't have an uncertainty when related to the transition of the Cs atom, so it doesn't have an error because it's an absolute reference and we measure other stuff using the physical definition of a second, like atomic clocks do.  But why doesn't the speed of light have uncertainty? Isn't the speed of light something that's measured physically?  Check out that .


I'm still using md5 hashing for my site and I need to upgrade, yet I don't know how... Here is the code that I'm using now     $salt1 = "mysite";     $salt1 = md5($salt1);     $salt2 = "passed";     $salt2 = md5($salt2);     $salt3 = "php";     $salt3 = md5($salt3);     $password1 = $salt1.$password1.$salt3;

It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection.  This question,   suggests that hashing multiple times may be a good idea, whereas  suggests using salt.  I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters.   The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?)   Also, should I store two fields in the database (one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer?  In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism.  Related questions that don't quite cover my question:


I cannot find enable-interactive-search in    gsettings set org.gnome.nautilus.preferences enable-interactive-search true.     I searched using    gsettings list-recursively | grep search     and    gsettings list-recursively | grep interactive     but no such option.  Can you help me disable this in Ubuntu 17.10 and later?

Until now I was using a "traditional" version of Nautilus: that that comes with Ubuntu 10.10. Now I'm using 3.6.3, included with Ubuntu 13.04 (most likely any recent version is equivalent for the scope of my question, anyway).  One major difference between the two is the search-as-you-type behavior: in classic versions of Nautilus, when you typed an input, the file with the closest alphabetical match would become the selected one, the eligible files/folders being restricted to the current directory.  The new behavior is to perform an optionally-global search instead.  Can one configure Nautilus to provide the previous functionality ?


Just one example I recently saw, I also hear people talking this way, and wonder why. Washington Post title today reads, "Many who have received the coronavirus vaccine wonder..." Another news title reads, "People who have had the vaccine..." Why is it necessary to add "have" or "have had" instead of simplifying the statement with, "Many who received the coronavirus vaccine wonder..."? Just seems like adding extra words, which looks/sounds wordy instead of getting to the point.

When is the present perfect tense used instead of the past tense?    I know that the present perfect tense is used when some adverbs (e.g., never, ever) are present in the sentence; the same is true for sentences like the following one.     When you returned, I have been at home since 3:00 PM.   In which other cases should I use the present perfect? Do the following sentences require it?     I have walked downtown everyday for a year.        I have been at home since 3:00 PM.


I want an easy way to clear cached pages on my asp.net-mvc website.  I have expensive DB operations so i often use outputcaching to make the site run faster.  I have code that looks like this:      [OutputCache(Duration = 30000)]     public ActionResult Index()     {          return View();     }      [OutputCache(Duration = 30000, VaryByParam = "*")]     public ActionResult GetData(MyParams myParams)     {         return PartialView("MyView", GetVM(myParams));     }   There are certain times (when things go wrong) when i want to explicitally clear this cache (regardless of the existing Cache duration)  is there anyway for full and partial page Outputcaching to remove the cached page and run through the full code ?  NOTE: I see that this question is asked already in general around asp.net like  but i dont see an asp.net-mvc specific solution  i have tried this but it doesn't seem to work:   public ActionResult ClearCache()  {       this.HttpContext.Response.RemoveOutputCacheItem("/MyController/Index.aspx");       this.HttpContext.Response.RemoveOutputCacheItem("/MyController/MyView.ascx");  }

For my blog I am wanting to use the Output Cache to save a cached version of a perticular post for around 10 minutes, and thats fine...  <%@OutputCache Duration="600" VaryByParam="*" %>   However, if someone posts a comment, I want to clear the cache so that the page is refreshed and the comment can be seen.  How do I do this in ASP.Net C#?


Prove that  $\lim_{n \rightarrow \infty} \frac{2^{n}}{n!} = 0$ using the hint that $0 < \frac{2^{n}}{n!} \leq 2 \, \left(\frac{2}{3}\right)^{n-2}$ for all $n \geq 3$? I know there is a thread already about this question but there is none that use this hint to solve this question. How can you use this hint to prove it?

Why is     $$\lim_{n \to \infty} \frac{2^n}{n!}=0\text{ ?}$$   Can we generalize it to any exponent $x \in \Bbb R$? This is to say, is     $$\lim_{n \to \infty} \frac{x^n}{n!}=0\text{ ?}$$     This is being repurposed in an effort to cut down on duplicates, see here: Coping with  duplicate questions.  and here: .


I want to use oldstyle figures as default for the whole document in LaTeX. How can I set that? I am using the default font.

I want to be able to use the \oldstylenums{} command as a default way for display my numbers, but only outside of math mode. Is this possible to do? I know some fonts come with this numbering system, but is there a way to make the old style the default way for displaying numbers in, let's say, the default font?  Thanks greatly!  Edit: MNW  \documentclass[a4paper,12pt]{extarticle}  \usepackage[english]{babel} \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{graphicx} \usepackage[colorinlistoftodos]{todonotes} \usepackage[a4paper,margin=1.5in]{geometry} \begin{document} This is a document in the default font, made on 12/3/2014. The numbers in this document need to be in the Old English style (where the number's height differs from each other). $$\text{This is a math block. These numbers should display as modern English style:}12/3/2014}$$ \end{document}


is lime juice as acidic as lemon juice and therefor uses 1:1 substitution with lemon juice to ensure low acid food is acidic enough for boiling water canning?

I attended a business meeting in the Midwest and one of our clients took our management team and a few other business partners to dinner at an awesome Mexican restaurant. When the appetizers were served I commented that it was a wonderful presentation and that everything looked very fresh, including the avocado slices.   Speaking to the woman seated across from me I said that even though I use a good amount of lemon juice, whenever I prepare avocados they still turned dark pretty quickly. This happens whether they are sliced, used in guacamole, etc. She responded that the secret is to use lime juice. She proceeded to tell me that she was born and raised in Central America and that it is customary there to use fresh limes or juice rather than lemon.  I have tried it and lime seems to work much better than lemon, so it would stand to reason that they are more acidic. However, I never thought there was that much difference. So, on to the questions.  Are limes more acidic than lemons? Are there any other differences in their properties that could make a difference?


I've just looked at the stats for a relatively new member and cannot believe the rep he supposedly made in one day, being a relative rookie.   Can this accumulation of rep for June 11 be explained? Was there something going on in the back end?   I posted a comment on one of his , which contained only links, advising that he should summarize the solution in the post, as per SO best practice. He replied with a very cocky "Sure ..." -  Where/How did he get that many reputation in one day? Hard to believe it's not a system error.

On Stack Exchange, users may gain a certain level of reputation.  What does reputation do? How can a user gain or lose reputation?   See also   in the Help Center  - Maximum amount of votes a user can use in a day and reputation requirements to vote.  - How to get an exact overview of the actions that got you your reputation.  - A full list of all privileges granted at each reputation level on all sites.


My daughter, who lives and works in Hong Kong, applied on line for a visa to visit Vietnam. She scanned her passport, paid about $200 using a credit card and received a fake visa. She cancelled her credit card. I am concerned about what kind of identity theft she may be exposed to.  Fortunately, she did not provide her social security # or drivers license number and she physically has possession of her passport. However, the thieves have her picture, passport # and date of birth. Appreciate all advice.

In one of the questions on this site, it was suggested the use of  to save a backup copy of your passport, in case you need to proof who you are if your original document is lost.   I like the idea, but what if someone gets access to your Dropbox folders and is able to acquire the copy of your passport.  The same goes for when you leave a copy of your passport at a hotel receptions desk. Once someone has the info printed on that copy, would that make it easier to steal your identity?


I need to know please any suggestion about how to create a custom login form for another type of users in drupal 8 , I have now /user/login is for administrator, but I need to add /account/login it's different for the first one and it's for a normal user and this form should use the functionnalities of Drupal 8.

I'm trying to customize user login form in /user/login page and I want to use a hook_form_alter function to add some awesome style and placeholder to each of user login form fields and remove or hide: "Enter your admin username" and "Enter the password that accompanies your username" description expressions under each of theme. To resolve this issue I added something like below code to my ThemeName.theme:  function ThemeName_form_alter(&$form, $form_state, $form_id) {   if ( $form['#form_id'] == 'user_login_form' ) {     $form['actions']['submit']['#attributes']['class'][] = 'button glow button-primary expanded';     $form['keys']['#attributes']['placeholder']['name'] = t('User name');     $form['keys']['#attributes']['placeholder']['password'] = t('Password');   } }   I try out many different ways but I can't get any result. in finally I want to achieve something like below image:   I read this pages but seems none work in Drupal 8:


We have an integer number  int x = 50;   in binary, it's  00110010   How can I change the fourth (4th) bit programatically?

How do you set, clear, and toggle a bit?


I'm trying to make a desktop launcher for Matlab in order to run it from the desktop. This is how my desktop entry looks like:  #!/usr/bin/env xdg-open [Desktop Entry] Version=1.0 Type=Application Terminal=false Icon[en_AU]=/home/userA/Pictures/matlab.png Name[en_AU]=Matlab Exec=/media/d/usr/local/MATLAB/R2014b/bin/matlab Name=Matlab Icon=/home/userA/Pictures/matlab.png   But when I run it, matlab start page appears for a second then disappears, this happened to me before when trying to run it from the folder itself, and I figured out that I need to sudo,  so I need to modify my desktop entry exec command so that it runs matlab without asking everytime for password. So if anyone could please advise

I'm trying to install a Matlab R2011a launcher for Unity in Ubuntu 12.04. I've tried  (although I know it's for 11.10 and mentions that even 11.10 is an unsupported OS for Matlab R2011a) but without any satisfactory solution.  This is my launcher file, /usr/share/applications/matlab.desktop:  #!/usr/bin/env xdg-open [Desktop Entry] Type=Application Icon=/usr/share/icons/matlab.png Name=MATLAB R2011a Comment=Start MATLAB - The Language of Technical Computing Exec=matlab -desktop Categories=Development;   I open the dash panel and search for "matlab". This launcher is found among applications. I click it, and Matlab's splash screen shows up, but when it disappears the program doesn't start. (I've verified with htop that no matlab-processes are running in the background either.)  If I add  Terminal=true   to the launcher file, the program starts OK, and opens a terminal as well as Matlab. However, both the terminal and Matlab itself show up in the Launcher area, with the Matlab icon, so it looks like I have two Matlab instances running when really it's only one. (Actually, they show up as two different programs, and not just two instances of the same - the icons are independent, not grouped together.)  This is definitely not optimal. I had hoped to create a launcher I can lock to the launcher area, and then that same icon will be the icon for the active Matlab instance when the program is running.  How do I create a launcher for Matlab that works as expected?  Update: I was apparently a bit unclear on my symptoms, I'll try to clarify a little. I've also tried some suggestions from the answers, and further investigated what happens. My current setup (a launcher file with Terminal=true and Exec=matlab -desktop -nosplash &) renders the following behavior:   I open Dash by pressing the Windows key on my laptop, and search for "matlab". It finds the launcher named "MATLAB R2011a". I click it. A terminal window opens, using the icon I referred to in the launcher file. Almost immediately, MATLAB's splash screen also opens, using the same icon (and thus being grouped with the terminal window in the launcher). The splash screen disappears and, so does one of the icons in the launcher. The MATLAB desktop environment opens, using a different version of the icon which is displayed next to the icon for the terminal window (not grouped with it).   I can lock the terminal window's icon to the launcher and successfully start MATLAB by clicking it, but it doesn't feel optimal that I start the program with one icon, and switch to it with another. I've also tried the following:   Exec without the ampersand & in the launcher command, but it didn't make a difference. Executing matlab -nosplash manually from a terminal still shows the splash screen. (What, then, does the nosplash option really do?)


I am running Ubuntu 12.04, which came with Cmake v 2.8.7.  I had need for a more current CMake, so I downloaded the source for 12.8.12.1, built, and installed it per directions.  The last step, make install I ran sudoed.  ./bootstrap make sudo make install   Now I want to run it, but I find that the old version is still invoked when I execute cmake from the command line:  jdibling@hurricane:/$ cd /; cmake --version; which cmake cmake version 2.8.7 /usr/local/bin/cmake jdibling@hurricane:/$    Odd, I think.  So I su and try it from there:  root@hurricane:~# cd /; cmake --version; which cmake cmake version 2.8.12.1 /usr/local/bin/cmake root@hurricane:/#    Why does which report the same directory, but cmake --version reports different versions?  How can I find where the new cmake was actually installed?  As suggested, I ran type:  jdibling@hurricane:/tmp/cmake-2.8.12.1$ type cmake cmake is hashed (/usr/bin/cmake) jdibling@hurricane:/tmp/cmake-2.8.12.1$ sudo su - root@hurricane:~# type cmake cmake is /usr/local/bin/cmake root@hurricane:~#

When looking for the path to an executable or checking what would happen if you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, whereis, whatis, hash, etc).  We often hear that which should be avoided. Why? What should we use instead?


I'm revisiting conditional probability* after many years and fear I never really understood it as well as I thought I did.  I have no problem taking the definition:  $$ \mathbb{P}(A\mid B) = \dfrac{\mathbb{P}(A \cap B)}{\mathbb{P}(B)} $$  and applying it to simple problems.  What I'm having trouble understanding is where this equation came from in the first place. I checked wikipedia:  which suggests it is a definition or even can be an axiom of probability.  If a definition, it can be shown that it honors the Kolmogorov axioms of probability and I sort of follow all this.  And clearly this definition, when used in problems, seems to agree with my intuitive ideas of how conditional probability should work.  Perhaps that's enough, but I still have this gnawing feeling that it should be "obvious" to me that this is the correct equation.  But I'm failing to see how conditional probability should be related to the intersection AND why dividing by P(B) is the correct way to go.  I tried thinking about the problem in terms of areas but that didn't help.  I do see that if we asked "what is the probability of B given B we would have:  $$ \mathbb{P}(B\mid B) = \dfrac{\mathbb{P}(B \cap B)}{\mathbb{P}(B)} $$  and this would equal 1, so perhaps that is some justification for the division by $\mathbb{P}(B)$.    Sorry if I'm rambling, but if this was completely clear in my mind, I wouldn't have a question!  So the questions are: 1.  Where does this equation come from? 2.  Can someone guide me how to see that this is what would come up with if one was trying to come up with a definition for the idea of "how likely is $A$ given $B$".    And as always, if there is a better group to ask this in, please let me know. -Dave  *I've started a course on Bayesian Probability:

What is some intuitive insight regarding the conditional probability definition: $P(A\mid B) = \large \frac{P(A \cap B)}{P(B)}$ ? I am looking for an intuitive motivation. My textbook merely gives a definition, but no true development of that definition. Hopefully that's not too much to ask.


Alright so I started learning python in my classes but I am very annoyed how you cannot declare variable types in python like other languages. What would be the best way to turn these strings into integers?  for lineNum, line in enumerate(sys.stdin): if(lineNum == 0):     xc, yc = eval(line)     xc = int(xc)     yc = int(yc) elif(lineNum == 1):     r = line     r = int(r) elif(lineNum == 2):     x1, y1 = eval(line)     x1 = int(x1)     y1 = int(y1) else:     x2, y2 = eval(line)     x2 = int(x2)     y2 = int(y2)

In Python, how can I parse a numeric string like "545.2222" to its corresponding float value, 545.2222? Or parse the string "31" to an integer, 31?  I just want to know how to parse a float str to a float, and (separately) an int str to an int.


Currently have a bat file set up to auto log into putty (cd "C:\Program Files\PuTTY" start PUTTY.exe -ssh "Sever IP" -l "User Name" -pw "Password") WORKS FINE!! But when i use the following syntax to automatically change the route to a different one it dose nothing (cd "C:\Program Files\PuTTY" start PUTTY.exe -ssh "Sever IP" -l "User Name" -pw "Password" -t -m cmds.txt) In the cmds text file is a simple CD C:\Subfolder\subfolder Is there an easier way..?? I have tried connection/ssh remote cmd in the putty GUI but dosent work Please help thanks

I start multiple PuTTY sessions everyday with a specific path in each session.  I have made a command in batch file as  Start "c:\putty.exe" abc@1.1.1.1 -pw abc123 22   How do I proceed further to open PuTTY directly in a specific remote directory.  I have 20 sessions.  Please assist.


This is a short story, probably from the 1960’s.  It begins with a little girl alone in a large space. There is a machine there that will dispense food if she performs correctly for it.  She learns that if she sticks her tongue out at it food will come out.  As the story progresses a few other children join her in this area.  They must all work together and perform various activities in order to receive food.  They end up distrusting each other but when a signal goes off they perform an elaborate dance to receive food. Finally, they are released into the real world and have become a team for military use.

I read this book about 20-30 years ago. It's about a group of teenagers who wake up in a huge room where each is on a separate platform. As the book progresses, they go unconscious and the platforms change, move or become connected. The children are punished or rewarded through a variety of methods including food and pain. The goal is to get them to either hurt each other, or see if they band together, I can't quite remember. Please tell me if this sounds familiar.


I'm using a PDF reader, iAnnotate, that allows one to search a document using java.util.regex.Pattern regexps.  Unfortunately, iAnnotate ignores case in all searches.  This happens even if you use an expression like [A] (it also finds "a"), and even if you specify the character in unicode (\u0041 means "A", but iAnnotate also finds "a").  Java regexps are not designed to ignore case by default, and I don't see any way to use them to override ignore-case behavior in the , but maybe there's something I'm not thinking of.  Any suggestions for possible regexp tricks to force a regexp to be interpreted with a specific case?  I know that this is strictly speaking an iAnnotate question, but I am interested in possible Pattern regexp solutions.

I've seen lots of examples of making an entire regular expression case-insensitive.  What I'm wondering about is having just part of the expression be case-insensitive.  For example, let's say I have a string like this:  fooFOOfOoFoOBARBARbarbarbAr   What if I want to match all occurrences of "foo" regardless of case but I only want to match the upper-case "BAR"s?  The ideal solution would be something that works across regex flavors but I'm interested in hearing language-specific ones as well (Thanks )  Edit  The link Espo provided was very helpful.  There's a good example in there about turning modifiers on and off within the expression.  For my contrived example, I can do something like this:  (?i)foo*(?-i)|BAR   which makes the match case-insensitive for just the foo portion of the match.  That seemed to work in most regex implementations except Javascript, Python, and a few others (as Espo mentioned).    The big ones that I was wondering about (Perl, PHP, .NET) all support inline mode changes.


In PHP there is a clear and concise coding standard. These guides have been defined by  in  PSR1: basic coding standards PSR12: extended coding standards  What are the equivalent coding styles for Python?

In python do you generally use  as your coding standards/guidelines?  Are there any other formalized standards that you prefer?


How to write subscript or superscript labels in QGIS 3.4?  Is there any function to do it without any external involvement like Character Map or etc?   I'm EXPLAINING that this is not a duplicate question and I want to use those scripts not only in MAP LAYOUT but everywhere!  For example like this below ▼

Is it possible to include subscript and superscript text in the title of a legend item in QGIS ?  I have tried using some text but this just appears in the title with no change to the contents.  I am looking to have layer titles such as   Annual NO2 concentration (μg/m3)  The superscript is not a big issue, as I can use the character map to get a 3, but I don't know how to get the subscript.


given that s is bounded below then ∃ t ∈ R such for all s ∈ S ,such that t≤s (1).then let suppose Inf S=t  If S is bounded below then the nonempty set S={-s, s∈ S} is bounded above.then -s ≥ t(2).  But in (1) we have t≤s.if we put negate this then -s≤t which is opposite of (2).  therefore Inf S=-Sup {-s: s∈ S}.  does it even make sense ?

Let $S\subset \mathbb{R}$ which is bounded below. Let $x\in S$ such   that $-x\in -S$. Prove $\inf(S)=-\sup(-S).$   By definition a lower bound on $S\subset \mathbb{R}$ is a number $a\in \mathbb{R}$ such that $s\ge a$ for each $s\in S$. Since $S$ is non-empty and is bounded below then there exists an infimum. How can I continue this proof?


I've seen both the 2003 anime and Brotherhood, and I know Brotherhood is more faithful to the manga than the 2003 anime. So I'm wondering if it's worth the effort to get all the Fullmetal Alchemist manga, or is Brotherhood so faithful to the manga that it's just the manga in anime form (i.e. the manga has no major plot twists that deviate from the anime)?

I haven't watched Anime in many years, but recently I've had time to get back into it. I've seen that one of my favorite series, Fullmetal Alchemist, has done a series reboot.  What I'm wondering is:  Does it present a lot of deep variations (plot-wise, character-wise or otherwise), or is it just the same series with updated art?


I have CentOS7 installed on my computer. uname -a prints the following: Linux c7 3.10.0-1127.el7.centos.plus.i686 #1 SMP Sun Apr 5 18:08:31 UTC 2020 i686 i686 i386 GNU/Linux  As stated in man uname page, uname -m denotes machine hardware name (i686 in my case), uname -p denotes processor type (i686 in my case) and uname -i denotes hardware platform (i386 in my case). I have been trying to find out what exactly every option means. After hours of searching I came to the conclusion that there are contradictions among given answers (even on StackExchange). As far as I understand, uname -m stands for what architecture the kernel was compiled for, therefore, in my case I have a Linux kernel which is build for i686 ISA (right?). But I have some misunderstanding about uname -p. People (and some docs) claim that it prints the ISA of the processor. I have i7-4800MQ, so uname -p should print something like x86_x64/amd64/x86-x64, but it prints i686. I think that it might be due to the reason that my CPU works in Legacy Mode (or so) using i686 ISA, since the distro is 32-bit (right?). The last option is uname -i which prints i386. I don't even have any assumptions about this one. I don't see any connection with i386 architecture in these conditions. Can someone clearly explain what does every parameter stand for in my case?

Why does this happen? Everything else printable with uname is shown. I am not looking into fixing this. Even the manual page of uname says that it's a common output.  I just want to know why.


I just installed Ubuntu 17.10. Everything seems to be working quite okay, except that I'm unable to use Synaptic. I installed it with (apparently) no problems, but when I click its icon, nothing happens.  Trying from the terminal this is the error I get:  No protocol specified Unable to init server: Could not connect: Connection refused (synaptic:3572): Gtk-WARNING **: cannot open display:   Any idea what this means?   Thanks in advance for the support.

I installed Ubuntu 17.10. Now I am having trouble with gksu:  $ gksu -dg synaptic No ask_pass set, using default! xauth: /tmp/libgksu-HgUjgQ/.Xauthority STARTUP_ID: gksu/synaptic/8760-0-alex-XPS-15-9530_TIME4974977 cmd[0]: /usr/bin/sudo cmd[1]: -H cmd[2]: -S cmd[3]: -p cmd[4]: GNOME_SUDO_PASS cmd[5]: -u cmd[6]: root cmd[7]: -- cmd[8]: synaptic buffer: -GNOME_SUDO_PASS- brute force GNOME_SUDO_PASS ended... Yeah, we're in... Unable to init server: Could not connect: Connection refused (synaptic:8767): Gtk-WARNING **: cannot open display: :1 xauth: /tmp/libgksu-HgUjgQ/.Xauthority xauth_env: (null) dir: /tmp/libgksu-HgUjgQ   If I don't use -g, the password dialog is disabled. So looks like a problem with creating a tty for root.  Any advice?


Google Chrome can let a webpage show notifications as a system notification (of the OS).  Is there a way to see a list of the past notifications?

The helpful companion to the OSX notifications center  per default logs all received notifications. You can define how big the log may get or disable logging in the application.  Since the latest update Growl offers to forward all notifications to the OS X Notification Center.  Does OS X log Notifications Center messages as well? If yes, where can I find them?  Why I am asking this:  OS X  in a SQLite 3.x database. I want to know if something similar happens with notifications as well. This could be a privacy issue when thinking of private messages or e-mails if too much information is stored.


How would I do this? I tried using contradiction, but got stuck halfway through. This unit is about induction, but I have no idea how I would use it to do this as it is not a sequence     4.6.15 (a) show that for any $k\in N$, if $2^{3k-1}+ 5\cdot 3^k$ is divisible by 11, then $2^{3(k+2)-1} + 5\cdot 3^{k+2}$ is also divisible by 11   $$(\forall k\in N)(\exists p\in Z)(\exists w\in Z)(2^{3k-1}+5\cdot 3^k = 11p)\Rightarrow(2^{3(k+2)-1}+5\cdot 3^{k+2})$$   we can prove this by contradiction.

Prove, by induction that $2^{3n-1}+5\cdot3^n$ is divisible by $11$ for any even number $n\in\Bbb N$.  I am rather confused by this question. This is my attempt so far:  For $n = 2$ $2^5 + 5\cdot 9 = 77$ $77/11 = 7$ We assume that there is a value $n = k$ such that $2^{3k-1} + 5\cdot 3^k$ is divisible by $11$. We show that it is also divisible by $11$ when $n = k + 2$ $2^{3k+5} + 5\cdot 3^{k+2}$ $32\cdot 2^3k + 5\cdot 9 \cdot3^k$ $32\cdot 2^3k + 45\cdot 3^k$ $64\cdot 2^{3k-1} + 45\cdot 3^k$ (Making both polynomials the same as when $n = k$) $(2^{3k-1} + 5\cdot 3^k) + (63\cdot 2^{3k-1} + 40\cdot 3^k)$  The first group of terms $(2^{3k-1} + 5\cdot 3^k)$ is divisible by $11$ because we have made an assumption that the term is divisible by $11$ when $n=k$. However, the second group is not divisible by $11$. Where did I go wrong?


Are there any algorithms that exist to encode messages written with pen and paper such that the messages can be encrypted/decrypted mentally? For example, Bob thinks of the text "This is my plaintext", writes down "siht si ym txetnialp", and then Larry (who knows the cipher) is able to understand the message "This is my plaintext",  just by looking at the cryptotext. The algorithm is simple enough that nothing needs to be written down besides the cryptotext.  This should not be a code, where a specific phrase means something else. I'm looking for an algorithm like a one-time-pad or modular addition method that can be completely contained in one's head.  The strength of the encryption is not as important - it doesn't need to stand up to a complex solver, just be very difficult to decode by someone who doesn't know the cipher. The more important feature here is speed - e.g. encrypting and writing a message can be done simultaneously in (on the order of) twice the time it takes to write it in plain English.

I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely.  However, I can think of many practical situations in which mental cryptography would be useful.  Is there a secure cryptosystem that is simple enough to be performed mentally?  Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.  How susceptible would any such system be to side channel attacks (like trash rummaging)?


I need to be able to know the Cloudflare IP for connections made to my server.  This is so I can determine if a connection is made through Tor. To do that, I need to send the tool the IP that the client CONNECTED TO. That is NOT my server's IP, that is the IP of the Cloudflare entry proxy, which is why I'm trying to pass the Cloudflare IP through fastcgi.   I have a block that looks like this:  # Preserve Cloudflare IP fastcgi_param CF-Proxy-IP $remote_addr; fastcgi_param TEST "abc123";  # CloudFlare set_real_ip_from 199.27.128.0/21; set_real_ip_from 173.245.48.0/20; set_real_ip_from 103.21.244.0/22; set_real_ip_from 103.22.200.0/22; set_real_ip_from 103.31.4.0/22; set_real_ip_from 141.101.64.0/18; set_real_ip_from 108.162.192.0/18; set_real_ip_from 190.93.240.0/20; set_real_ip_from 188.114.96.0/20; set_real_ip_from 197.234.240.0/22; set_real_ip_from 198.41.128.0/17; set_real_ip_from 162.158.0.0/15; set_real_ip_from 104.16.0.0/12; set_real_ip_from 172.64.0.0/13; set_real_ip_from 2400:cb00::/32; set_real_ip_from 2606:4700::/32; set_real_ip_from 2803:f800::/32; set_real_ip_from 2405:b500::/32; set_real_ip_from 2405:8100::/32; real_ip_header CF-Connecting-IP;   But it's not going through and the dummy headers I set do not get seen in phpinfo(). I'm not sure what else I can do because after the real_ip_header goes through, all original CF data is lost.

My environment has user requests passing through a number of systems:  [Client] --> [ELB] ---> [nginx] --> [web]  (ELB = AWS Elastic Load Balancer)  Thanks to this , I have nginx determining and passing the correct client IP address to the upstream servers (web) with the X-Forwarded-For and X-Real_IP headers. The relevant nginx config:      real_ip_header      X-Forwarded-For;     set_real_ip_from        10.0.0.0/8;     real_ip_recursive   on;     proxy_set_header X-Real-IP $remote_addr;   My problem is this, the Real IP module in nginx replaces the existing $remote_addr variable with the result of its X-Forwarded-For calculations. This gives me the originating client IP, but I'm losing the IP address of the system that actually sent the request to the proxy (i.e. the ELB).  Overall, having the client IP is more important to me, but I would like to be able to log the full chain of requests so I can understand (and debug) how traffic is flowing. Currently, I can only have nginx log the client IP, its own IP, and the upstream server IP. I would like to be able to log the ELB IP as well.  I see  asked the same  in 2013, with little luck. Has anything changed or improved since then?


To analyse $f:\mathbb{C} \rightarrow \mathbb{C}$ can I just analyse $f:\mathbb{R}^2 \rightarrow \mathbb{R}^2$ ?  My question is why would a complex valued function have different properties than a real 2-valued function, since I can construct a isomorphism between the spaces $\mathbb{R}^2$ and $\mathbb{C}$. Can I define derivatives and integration in the same way because of this isomorphism?   I'm asking this specially because I'm studying Complex Analysis this semester, and read about the result "If $f:\mathbb{C} \rightarrow \mathbb{C} \in C^{1}$ then $f \in C^\omega$" and I'm wondering if there is an analog one for real 2-valued functions.

Is there any advantage to studying  single variable complex analysis as it is right now instead of just studying the world of the functions $f:\Bbb R^2 \to \Bbb R^2$?  I'm asking this because any function $\gamma: \Bbb C\to \Bbb C$ can be written as $\gamma(z)=u(x,y)+v(x,y)i$ and so we can associate the function $F: \Bbb R^2 \to \Bbb R^2, F(x,y)=(u(x,y),v(x,y))$ and study all the properties of a complex valued function as a real vector valued one.


I want to automatically delete the backup files(those ending with ~) from everywhere on my computer.  I tried to write a simple script usinglocate command, but I'm stuck at deleting file having space in there name, like this  /home/abc/def/Unnamed Document~   Can you provide a script to delete backup files(considering that some of them have space in there name).

Many days ago, I found this useful bash alias (contents of my ~/.bash_aliases)  # aliases  # finds temporary files ending with '~' and deletes them alias rm~='find . -name '*~' -print0 | xargs -0 /bin/rm -f'   Now I tried to use rm~ after cd to some directory containing 3 files ending in ~  I got this error in terminal, and files did not get deleted  find: paths must precede expression: 1n.in~ Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]   Also when I tried rm~ from /home/me, it seems to be doing nothing. Or it might be taking a lot of time.  Please tell me why am I getting error, and how to fix it.  Thanks!


I kept getting the error "Command terminated by signal 11" when I try to save a string into an array of strings. After changing the code from the link below, now the name prints out ���W.   I used this  to fix my code off of but it is still causing me to get the error "Command terminated by signal 11".       #include<stdio.h>     #include<string.h>      void getName(char* c[], int size);     int main(void) {         int yenoSize = 0;         int strSize = 0;     char name1[30];     char* name[30];     char* students[5][30];      for(int i=0;i<1;i++){     getName(name, strSize);     students[i][0] = name1;     }      for(int k=0; k<1;k++){     printf("Student Name: %s \n", students[k][30]);      }      }      void getName(char* c[], int size){     char name1[30];     printf("Enter student name: ");     fgets(name1, 30, stdin);     c[0] = &name1[0];     printf("%s", name1);      }   The output is supposed to print out the name that the user inputs (Student Name: Jon) but it is currently printing ���W. How can I fix the problem? I believe the problem exists with the name pointer pointing to null. Is that the problem? I appreciate the help!

As a follow-up to :  From what I've seen, this should work as expected:  void greet(){   char c[] = "Hello";   greetWith(c);   return; }   but this will cause undefined behavior:  char *greet(){    char c[] = "Hello";   return c; }   If I'm right, what's the best way to fix the second greet function? In an embedded environment? On a desktop?


Whenever there is question about credibility of Properties, I see that most of the discussion happens around functions/methods vs properties. But I would also like to know the compelling reason to use property with associated private field vs public field directly itself, incase of most common get/set behaviors with no other processing, I mean this way  public string CustomerName;   vs  private string customerName; public string CustomerName { get{return customerName;} set(string value){this.customerName=value;} }

In C#, what makes a field different from a property, and when should a field be used instead of a property?


I encountered with this error while attempted compiling fasta36 on my Ubuntu 12.04.3 64 bit machine:  /usr/bin/ld: cannot find -lz collect2: ld returned 1 exit status make: *** [fasta36] Error 1   I used following command:  make -f ../make/Makefile.linux64_sse2   I guessed it could be due to absence or broken symbolic link so tried to find the correct file. I could see in my /usr/lib directory following files:  lrwxrwxrwx 1 root root     16 Nov 18  2011 libzbar.so.0 -> libzbar.so.0.2.0 -rw-r--r-- 1 root root 187480 Nov 18  2011 libzbar.so.0.2.0 lrwxrwxrwx 1 root root     25 Nov 12 18:54 libzeitgeist-1.0.so.1 -> libzeitgeist-1.0.so.1.1.4 -rw-r--r-- 1 root root 122048 May  4  2012 libzeitgeist-1.0.so.1.1.4 lrwxrwxrwx 1 root root     18 Nov 12 18:54 libzephyr.so.4 -> libzephyr.so.4.0.0 -rw-r--r-- 1 root root  55672 Apr 30  2011 libzephyr.so.4.0.0 lrwxrwxrwx 1 root root     23 Nov 26  2010 libzvbi-chains.so.0 -> libzvbi-chains.so.0.0.0 -rw-r--r-- 1 root root  60112 Nov 26  2010 libzvbi-chains.so.0.0.0 lrwxrwxrwx 1 root root     17 Nov 26  2010 libzvbi.so.0 -> libzvbi.so.0.13.1 -rw-r--r-- 1 root root 546768 Nov 26  2010 libzvbi.so.0.13.1   I have no idea which one of these represent the -lz?  Could someone help me sort this one out here? I appreciate your time and help.

I'm trying to install lxml on a virtual machine running ubuntu/trusty64 in a virtualenv however i get this error below and can't get my head around it.  /usr/bin/ld: cannot find -lz   the first time this error occurred i looked into installing lz. i installed it using sudo apt-get install mtools which contains lz however the error still occurs therefore i'm thinking this could be a symbolic link problem maybe a file is supposed to be linked to lz but not sure what file. lz has a symlink to uz but i dont know what effect that has and don't want to change that incase it breaks something else. any ideas to point me in the right direction?  building 'lxml.etree' extension  creating build/temp.linux-x86_64-2.7  creating build/temp.linux-x86_64-2.7/src  creating build/temp.linux-x86_64-2.7/src/lxml  x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/libxml2 -Isrc/lxml/includes -I/usr/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.linux-x86_64-2.7/src/lxml/lxml.etree.o -w  x86_64-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/src/lxml/lxml.etree.o -lxslt -lexslt -lxml2 -lz -lm -o build/lib.linux-x86_64-2.7/lxml/etree.so  /usr/bin/ld: cannot find -lz  collect2: error: ld returned 1 exit status  error: command 'x86_64-linux-gnu-gcc' failed with exit status 1  ---------------------------------------- Cleaning up... Command /home/vagrant/.virtualenvs/devenv/bin/python -c "import setuptools, tokenize;__file__='/home/vagrant/.virtualenvs/devenv/build/lxml/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-yUqdLy-record/install-record.txt --single-version-externally-managed --compile --install-headers /home/vagrant/.virtualenvs/devenv/include/site/python2.7 failed with error code 1 in /home/vagrant/.virtualenvs/devenv/build/lxml Storing debug log for failure in /home/vagrant/.pip/pip.log  (devenv)vagrant@vagrant-ubuntu-trusty-64:/vagrant/woowoo/woowoo_webapp$ ls -l /usr/bin/ld lrwxrwxrwx 1 root root 6 Sep 16 16:11 /usr/bin/ld -> ld.bfd (devenv)$ vim /usr/bin/ld.bfd  (devenv)$ ls -l /usr/bin/ld.bfd -rwxr-xr-x 1 root root 1050912 Sep 16 16:10 /usr/bin/ld.bfd (devenv)$ ls -l /usr/bin/ld lrwxrwxrwx 1 root root 6 Sep 16 16:11 /usr/bin/ld -> ld.bfd (devenv)$ ls -l /usr/bin/lzlrwxrwxrwx 1 root root 2 Oct 10  2013 /usr/bin/lz -> uz (devenv)$ ls -l /usr/bin/uz -rwxr-xr-x 1 root root 2496 Oct 10  2013 /usr/bin/uz


Scott Summers (aka Cyclops) has super powerful energy beams constantly firing from his eyes.  The only way he can prevent the beams from destroying everything is by closing his eyes or by wearing protective eye wear (apparently sunglasses are impervious to his energy beam).  In any other instance, his eyes are firing a bright red beam of energy.  How can he see through that?

From official :     Due to a head injury, Cyclops is unable to shut off his optic blasts   at will and must therefore wear ruby quartz lenses to block the beams.   From the same page:     Cyclops possesses the mutant ability to project a beam of heatless   ruby-colored concussive force from his eyes, which act as   inter-dimensional apertures between this universe and another.   When his eyes are always blocked by ruby-colored beam of concussive force, how does he see?


I'm trying to replace the first occurrence in a file using sed:  sed -i s/he/He/ dummy.txt   Instead of replacing first occurrence, it replaces all the occurrences, even without /g.  According to the documentation it should replace the first only.   The sed version which is:  GNU sed version 4.1.5   Am I missing anything? Or does the behavior differ for different sed implementations?

Original file claudio antonio claudio michele  I  want to change only the first occurrence of "claudio" with "claudia" so that I would get the following: claudia antonio claudio michele  I have tried the following: sed -e '1,/claudio/s/claudio/claudia/' nomi  The above command performs global substitution (it replaces all occurrences of 'claudio') . Why?


I'm trying to prove "A graph $G$ with the chromatic number $𝑘$ has a proper coloring with a walk with $k$ vertices in $k$ different colors". I tried using induction to prove this statement such as color the graph, remove edges to change it into a $(k-1)$-colorable graph, and then connect the $(k-1)$-walk with one deleted edge. From here on I'm not sure how to proceed to connect the walk, especially about how to ensure I can find such a vertex to connect. Thanks in advance!

Suppose that the chromatic number of graph $G$ is $m$ and $c\colon \operatorname{V}(G) \to \{1,2,3,\dotsc,m\}$ is a proper $m$-coloring of $G$. Then must there be a path $x_1, \dotsc, x_m$ in $G$ with $c(x_i) = i$ ?   After trying many examples, I think the answer is a yes. However I am finding it difficult to actually prove it. Is a proof by contradiction a good way to start this?


I want to have a deep understanding of probability.  I've tried William Feller's first book on Probability, and E.T Jaynes' Probability theory - the logic of science (which is very different from most probability books.) But, neither books could hold my interest for long. The first was too boring. The second was too tough to understand.  Please suggest some strategies and books that can help me.  As far as the level of my current knowledge goes, I know basic combinatorial probability, conditional probability, Bayesian probability, binomial, Poisson and Normal distribution. I only know how to apply the normal distribution, not how to derive it.

I'm embarrassed to say that I have a PhD and hold an asst professorship, but get tripped up when reading statistics research. I am in a field of Business that is similar to IO Psychology or Social Psych. I spend too much time reading applied stats books, but I find even with all the reading I don't have a firm grasp of what I'm actually doing. Everything is very 'seat of the pants.' (As sad as it seems, I think this is not a unique situation among the faculty in the social sciences...) The biggest problem comes when I need to apply a rarely used stat technique. I can find an article from a mathematical stats journal with the equations that would solve my problem, but I don't have the math to convert those into code. I am forever relying on other prof's R packages, and crossing my fingers hoping it will work (I can't even check to verify if it did or not). It's been over 15 years since I took Calculus and Algebra in undergrad, and I think I want to start at the beginning and truly understand probability and statistics.   I am starting with  and  for a quick refresher of the basics -- I know it's hard to believe, but in an applied research field we rarely have use for sin or cos. I'm even trying to finally learn how to correctly do a proof, using the books from Velleman ("") and Houston ("") -- I'm serious about doing this right and understanding the subject. From there I want to move on to (correctly) learn the Calculus and Linear Algebra I need to tackle probability and statistics. I was thinking of using  and  books. But  comes highly recommended as well. After that I am completely at a loss. Further, I don't know how far to go into Calculus or Linear Algebra before I reach diminishing returns. (Apostle introduces Probability in the  -- is it vital that I work through everything preceding it before tackling Probability?)  So my question is: if you had to do it over again with the goal of truly, deeply understanding statistics, where would you start? What books are the modern path to deep understanding? I would like to follow a modern path so that I can understand current research in statistics, including Bayesian approaches. But not in a machine learning context (which seems to be the all the rage at the moment), rather a social science / design and analysis of experiments / multilevel modeling context. Perhaps my goal would be the work of Andrew Gelman;  showed me how I should be looking at modeling and statistics (simulation, uncertainty estimates everywhere, bayesian inference, and so on).  How should I go about relearning this material with that end goal in mind?    Update 1: Possible texts, starting from scratch with a focus on proofs and deep understanding. Not necessarily one after another.  Relearn the basics:    by Velleman  by Houston  and  by Gelfand (for understanding why and how instead of what)  by Simmons (for reference)  by Lockhart (for inspiration)   Calculus (which one(s), and how deep?):    by Strang  and  by Apostol   by Spivak ()   by Curant (and II/1 II/2?)   Linear Algebra (which one(s) and how deep?):    by Strang  by Searle  by Gentle   Probability (which one(s)?):    and  by Feller  (for intuitive understanding)  by Hoel, Port, Stone  by Resnick (for measure theoretic / modern approach?)  by Mosteller   Core Statistics (which one(s)?):    by DeGroot and Schervish  Casella and Berger   Other suggestions? Again with the goal of understanding and developing (or at least implementing) new methods in hierarchical modelling (generalized and linear).


I have a form with a few fields in them. I wish to validate all of them before I could submit the details entered. For example, First Name should have atleast 1 character. Email should match the Email-format. Password should be atleast 6 characters and so on...  Based on the validation, I have to put a green-right-tick or a red-cross symbol at the end of the field.  I'm working on an android app, but I think a similar problem could occur in a web app too.  Now, my question is when should I validate the fields? By validating, I mean either I put the right-tick or, the wrong-cross with Error Message. Here are the options that I'm considering right now:   I validate them with every keystroke. I validate a particular field when focus from that field goes away. That's when the user is done typing into that field. I start validating when a user pauses typing for sometime, say 0.5 seconds.   I know the question might be opinion-based, but from the perspective of an End user, what would be the best experience? Please add more options as well, if we can have something better than the above 3 options.

I'm working on a registration form with real-time inline validation. I'm wondering when we should trigger error messages:   before, when the field is in focus and until the user has entered a valid answer while, when the user is typing and until the has entered a valid answer after, when the field is out of focus


Please have a look at . It has 4 answers, out of which 1 is deleted and another one has been posted by me. There is another answer which was posted a minute later after my answer.  Since I posted the answer a minute earlier and thus I got the early upvotes. The answer didn't get as many upvotes as mine. I'm really not sure if that is the reason, but the OP of that other answer seems to be commenting everywhere to get his answer noticed. Have a look at these comments. ,   &  .  I'm sure that the other answer is equally good as mine, or may be better also, but does it mean we should go around posting comments to the OP to get our answers noticed? Is it a good practice? Because I feel that as you've already posted the answer, the OP(and the other users) are bound to see that and if they feel its really helpful, they would certainly go ahead and upvote it so that its visible at the top. There really isn't any need to keep posting comments to get your answer noticed. Am I right about this?! Or getting our answers more visibility by comments everywhere is a practice followed on Stack Overflow(and if it, I really don't feel its nice).

I've started to flag a few of these once I had seen one too many of them, but I'm not sure whether I'm doing the right thing.  This is an example of what I'm talking about (this comment is on the question, but sometimes on their own answers too):    Are they something that should be considered acceptable, and if not, are they bad enough to be "flaggable"?


Looking for help to put such structure together.  Have base generic class:  public class A<T>     where T: class {     public T info { get; set; }     }   Works good for one step inheritance like:  class B : A<BInfoClass>{}   But need same for higher hierarchy members like, but without making all classes generics:  class C : B<CInfoClass>{}   Need possibility to have specific "info" type for each B, C, D etc. ("info" classes derive from one base):

Is it possible for a generic interface's type to be based on a specific parent class?  For example:  public interface IGenericFace<T : BaseClass> { }   Obviously the above code doesn't work but if it did, what I'm trying to tell the compiler is that T must be a sub-class of BaseClass.  Can that be done, are there plans for it, etc.?  I think it would be useful in terms of a specific project, making sure a generic interface/class isn't used with unintended type(s) at compile time.  Or also to sort of self-document: show what kind of type is intended.


I have been trying to create a tool to make a simple select then zoom to selected but I've been running into some issues. I've been using the code from this original posting (). It seems like his solution was never solved.  Here is the code that I have:  import arcpy  mxd = arcpy.mapping.MapDocument("CURRENT") df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0] lyr = arcpy.mapping.ListLayers(mxd, "PARCELS", df)[0] arcpy.env.overwriteOutput = True arcpy.env.workspace = "C:/ArcMap/COGO_Template"  wrk = arcpy.env.workspace arcpy.AddMessage("Workspace added") FClass = arcpy.GetParameterAsText(0) Field = arcpy.GetParameterAsText(1) Feature = arcpy.GetParameterAsText(2)  FClassLayer = arcpy.MakeFeatureLayer_management(FClass, "FclassLayer")  where_clause = """{} = '{}'""".format(arcpy.AddFieldDelimiters(FClass, Field),                                       Feature)  # I have added extra pair of single quotes for selecting strings arcpy.AddMessage(where_clause) arcpy.SelectLayerByAttribute_management(FClassLayer, "NEW_SELECTION", where_clause) arcpy.CopyFeatures_management(FClass, "C:/ArcMap/COGO.gdb/SelectionSites") df.zoomToSelectedFeatures() arcpy.RefreshActiveView() arcpy.AddMessage("All done!")   My parameters are as follows:  InputFeatureClass = Data Type: Feature Class, Required, Input, No Multivalue, Default: Database Connections\Connection to gis.sde\PARCELS  InputField = Data Type: Field, Required, Input, No Multivalue, Obtained from Input Feature Class  InputValue = DataType: String, Required, No Multivalue  The tool runs fine and shows no errors but unfortunately no parcel is selected and it doesn't zoom. Something to note as well is it takes about 2 minutes to run.  When I manually select by attribute in the attribute table (select, select by attribute, put in the parcel number, click ok), then run the tool, it zooms to the layer

I selected data by using select layer by attribute, then I need to only select these selection and zoom in to the selection.  my code is this, it can zoom in base on the scale I set, but I see other adjacent polygon that has other Code_No, why?  Layer = arcpy.mapping.ListLayers(mxd, "lyr", df)        arcpy.SelectLayerByAttribute_management(lyr, "NEW_SELECTION", "Code_NO = '%s'"%mycodeNo)            df.extent = lyrLayer1.getSelectedExtent() df.scale *= 2


I am using Ubuntu 12.10.  Please outline the different ways I can upgrade to 13.04.

How can I safely upgrade an Ubuntu installation from one release to another? What should I do before upgrading to ensure it goes smoothly, and is there any clean-up I need to do afterwards?  In particular, do I need to do anything special if I am using packages from PPAs, if I have a graphics card that needs drivers, or if I'm running a custom Linux kernel?  This is a general question , but as example we take Ubuntu 12.04 and Ubuntu 12.10


According to classical physics, an electron orbiting the nucleus would emit electromagnetic radiation. Losing energy in that way, it would spiral into the nucleus and the atom would collapse. Quantum mechanics explains that the electron cannot be treated as a classical particle having a definite position and velocity. The best we can do is specify the probability of it manifesting itself at any point in space and then something about Heisenberg uncertainty principle. How does quantum mechanics explain why the orbiting electron doesn't emit EM radiation and the atom doesn't collapse?

We all learn in grade school that electrons are negatively-charged particles that inhabit the space around the nucleus of an atom, that protons are positively-charged and are embedded within the nucleus along with neutrons, which have no charge. I have read a little about electron orbitals and some of the quantum mechanics behind why electrons only occupy certain energy levels. However...  How does the electromagnetic force work in maintaining the positions of the electrons? Since positive and negative charges attract each other, why is it that the electrons don't collide with the protons in the nucleus? Are there ever instances where electrons and protons do collide, and, if so, what occurs?


I'm trying to change directory in shell script to the one given by the command line argument.  #!/bin/bash chmod 755 findfn.sh dir=$1  while [ -d "${dir}" ] do     cd $HOME/"$1" done   I've looked at many other posts and tried:   cd "dir" cd ~/"$1" cd source "$1" Removing #!bin/bash Changing chmod 755 to chmod 700, etc   Where am I going wrong?  EDIT Just tried this   alias dirc="cd /home/$1"     echo $PWD   but it still doesnt change directory, it just keeps printing out  "/home"

I'm trying to write a small script to change the current directory to my project directory:  #!/bin/bash cd /home/tree/projects/java   I saved this file as proj, added execute permission with chmod, and copied it to /usr/bin. When I call it by: proj, it does nothing. What am I doing wrong?


#!/usr/bin/env bash set -euxo pipefail  echo $(echo "$THIS_VAR_DOES_NOT_EXIST" | cat)  echo "WTF"   Running this script produces:  ./wtf.sh  ++ cat ./wtf.sh: line 4: THIS_VAR_DOES_NOT_EXIST: unbound variable + echo  + echo WTF WTF   Why does it run the last command echo WTF? I assume it would terminate the script at line 4 (due to the presence of set -e).  Does subshells not automatically inherit the set -e option? Or is this some special behaviour?    On the other hand if it seems if I don't echo the command and instead output it to a variable it behaves as expected... What?????  #!/usr/bin/env bash set -euxo pipefail  echo $(echo "$THIS_VAR_DOES_NOT_EXIST") echo "this works fine..."  yolo=$(echo "$THIS_VAR_DOES_NOT_EXIST") echo "this does not"  echo "..."   Produces:  ./wtf.sh: line 4: THIS_VAR_DOES_NOT_EXIST: unbound variable + echo  + echo 'this works fine...' this works fine... ./wtf.sh: line 7: THIS_VAR_DOES_NOT_EXIST: unbound variable + yolo=   Why does this behave differently?

So I like to harden my bash scripts wherever I can (and when not able to delegate to a language like Python/Ruby) to ensure errors do not go uncaught.  In that vein I have a strict.sh, which contains things like:  set -e set -u set -o pipefail   And source it in other scripts. However, while pipefail would pick up:  false | echo it kept going | true  It will not pick up:  echo The output is '`false; echo something else`'    The output would be   The output is ''  False returns non-zero status, and no-stdout. In a pipe it would have failed, but here the error isn't caught. When this is actually a calculation stored in a variable for later, and the value is set to blank, this may then cause later problems.  So - is there a way to get bash to treat a non-zero returncode inside a backtick as reason enough to exit?


In much  I found, punctuation (comma, period, etc) follows an equation when necessary. However, in , there is no punctuation after an equation, as far as I understand from reading it. Is this a difference between American and British English? I like no punctuation after the equation because it looks clean. My friend thinks there should be punctuation because it is a part of a sentence.

This isn't a pure English question, but it is about writing style: Sometimes entities that aren't words end up being in sentences. I know that when mathematical expressions are inline as follows:  We used the equation x + y = z. This is the next sentence.  they are treated as any other word, and the sentence needs to end with a period. But suppose I have text in a paper such as:  We used the equation x + y = z This is the next sentence.  Notice that the equation isn't inline. Should there still be a period after the equation (right after z) to indicate the end of the sentence?


I want to test if the means of different groups (tissue types) are different using one-way ANOVA. Most of the groups have replicates but there is one group that only has one sample. Like this:  heart, heart, heart, skin, skin, skin,skin, bone, bone, bone, brain  In the above example, only one sample/data point for brain and the other three tissues have replicates.   So can ANOVA work for this data or it has to require all groups have replicates?

For an ecology project, my lab group added vinegar to 4 tanks containing equal volumes of pond water, 1 control with no elodea (an aquatic plant) and 3 treatments with the same amount of elodea in each. The purpose of adding the vinegar was to reduce the pH. The hypothesis was that the tanks with elodea would go back to their normal pH quicker. This was indeed the case. We measured the pH of each tank daily for about two weeks. All the tanks eventually returned to their natural pH, but the length of time that this took was much shorter for the tanks with elodea.  When we told our professor about our experimental design, he said that there exists no statistical test that can be performed on the data to compare the control to the treatment. That because there was no replicate for the control (we only used one control tank) we cannot calculate variance and so we can't compare the sample means of the control and the treatment. So my question is, is this true? I definitely understand what he means. For example, if you took the height of one man and one woman, you can't draw conclusions about their respective populations. But we did 3 treatments, and the variance was small. It seems reasonable to assume that the variance would be similar in the control?  Update:  Thank you for the excellent answer. We got more water and elodea from the wetland and decided we would run the experiment again with smaller tanks but this time with 5 controls and 5 treatments. We were going to combine this with our original data but the starting pH of the tanks was different enough that it doesn't seem valid to consider the new experiment to be sampled from the same population as the original experiment.  We considered adding different amounts of elodea and trying to correlate speed of pH remediation (measured as time elapsed until pH returned to its original value) with amount of elodea, but we decided that wasn't necessary. Our objective is only to show that the elodea makes a positive difference, not to construct some kind of predictive model for exactly how the pH responds to differing amounts of elodea. It would be interesting to determine the optimal amount of elodea, but that's probably just the maximum amount that can survive. Trying to fit a regression curve to the data wouldn't be especially illuminating because of the various complicated changes that occur to the community when adding a large amount. The elodea dies, decomposes, new organisms start to dominate, and so on.


Running (X)Ubuntu 10.04.2 LTS behind a router.  I just received an email from my root account on that machine, with the following subject:     *** SECURITY information for <hostname>:   The message body contained this warning:     <hostname> : jun  1 22:15:17 : <username> : 3 incorrect password attempts ; TTY=unknown ; PWD=/ ; USER=root ; COMMAND=/bin/sh /tmp/tmpPHBmTO   I can see no /tmp/tmpPHBmTO file, though there is a file named /tmp/tmpwoSrWW with a timestamp dating from 2011-06-01 22:14, so just before the mentioned date/time. It's a binary file, and the content doesn't look familiar to me.  Also, that file only has -rw------- permissions.  As I read it, this means that someone (or something) has (had) access to my machine.  Apparently not root access (yet), but still, enough to write files to my /tmp directory at the very least.  Does someone have any pointers as to where I could look for more information: who could have done this, and how they could have done this?  My router is configured to allow access to forward traffic for SSH, HTTP (nginx acting as reverse proxy for one of several other services), SMTP, POP (postfix) and IMAP (dovecot), and also port 51413 (Transmission).

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.