Suppose there are 200 files in /tmp  e.g.:  {abc1xyz,abc2xyz,abc3xyz..abc200xyz}  I want to write "hello" in the files from abc38xyz to abc53xyz
How to redirect standard output to multiple log files? The following does not work:  some_command 1&gt; output_log_1 output_log_2 2&gt;&amp;1
Often I need to recall the different \tracing commands; and a couple of times I stumbled on some webpages that worked fine for me; sadly, I didn't keep them, and my searches don't take me there anymore.   So I thought I'd ask about links to where one can read a list of \tracing commands?   For instance,  mentions:  \tracingall \tracingassigns \tracingcommands \tracinggroups \tracingifs \tracinglostchars \tracingmacros \tracingnesting \tracingonline \tracingoutput \tracingpages \tracingparagraphs \tracingrestores \tracingstats \tracingscantokens   .. but, I'm pretty sure there was something like \tracingboxes (and not so sure if there was something like \tracingglues); yet I cannot find any resources mentioning those. Manifold that is NOT smooth Could someone provide an example of a manifold that is not smooth? All manifolds that come to mind are smooth! By a manifold, I mean a hausdorff, second countable locally euclidean space. Prove $\gcd(a+b,a^2+b^2)$ is $1$ or $2$ if $\gcd(a,b) = 1$ Assuming that $\gcd(a,b) = 1$, prove that $\gcd(a+b,a^2+b^2) = 1$ or $2$.   I tried this problem and ended up with $$d\mid 2a^2,\quad d\mid 2b^2$$ where $d = \gcd(a+b,a^2+b^2)$, but then I am stuck; by these two conclusions how can I conclude $d=1$ or $2$?  And also is there any other way of proving this result? I have a string "1112224444' it is a telephone number. I want to format as 111-222-4444 before I store it in a file. It is on a datarecord and I would prefer to be able to do this without assigning a new variable.  I was thinking:  String.Format("{0:###-###-####}", i["MyPhone"].ToString() );   but that does not seem to do the trick.  ** UPDATE **  Ok. I went with this solution  Convert.ToInt64(i["Customer Phone"]).ToString("###-###-#### ####")   Now its gets messed up when the extension is less than 4 digits. It will fill in the numbers from the right. so  1112224444 333  becomes  11-221-244 3334   Any ideas? "Email" or "e-mail"? Which way of writing the word: "Email" or "e-mail" is correct? Both variants seem to be in wide use. If both ones are okay, maybe there is a difference in contexts they have been used (one is more formal than the other)? Chi-squared test when two vectors have different lengths I want to compare two groups (vectors) having different lengths to see if their distributions differ considerably. However, when I use chisq.test, I get an error due to inequalities of lengths:  &gt; chisq.test(factor(Group1), factor(Group2))   results in:  Error in chisq.test(factor(Group1[, col]), factor(Group2[, col])) :  'x' and 'y' must have the same length   Could someone help me with this? Thanks. What do parentheses surrounding an object/function/class declaration mean? I'm new to both JavaScript and . In YUI library examples, you can find many uses of this construct:  (function() {     var Dom = YAHOO.util.Dom,     Event = YAHOO.util.Event,     layout = null,         ... })();   I think the last couple of parentheses are to execute the function just after the declaration.  ... But what about the previous set of parentheses surrounding the function declaration?  I think it is a matter of scope; that's to hide inside variables to outside functions and possibly global objects. Is it? More generally, what are the mechanics of those parentheses? My employer didn't send me W-2 for December 2015. In fact, he told me that I wasn't on payroll for the two months(Dec/Jan) I worked for them so I am not sure whether he will be able to generate W-2 for me or not. I am wondering should I call IRS and inform them about the same, and probably they will call the employer? Or should I report my December 2015 earnings as Miscellaneous and report to IRS while filing taxes? Or what other options do I have? I am a non resident alien on F-1 Visa. My employer also has not paid me full salary as promised, which I am discussing with him.  Also, I got paid by check in January month for my December payment, so I am wondering does this apply for 2015 tax filing as I got paid in January 2016? Missing $ inserted Reverse Triangle Inequality in vector space I have already proved Triangle Inequality $\lVert v+w\rVert \le \lVert v \rVert+\lVert w \rVert$ in vector space $\mathbb{R}^n$. However, I'm having difficulties proving the Reverse Triangle Inequality in the vector space.  I have started with   $$\lVert v \rVert^2=v \cdot v-w\cdot w+w\cdot w \le \lVert v-w \rVert+\lVert w \rVert^2$$ $$\lVert w \rVert^2=w \cdot w-v\cdot v+v\cdot v \le \lVert w-v \rVert+\lVert v \rVert^2$$  based on the Triangle Inequality but I don't know if it is correct. If this is right, I think I can go on with proving it the same way I would the normal Reverse Triangle Inequality. Use of quotes in GNU grep regular expressions What is the "Event Horizon" of a black hole The following  (links to pdf) in the  has no provided source. The book  by Ash and Gross seems to use a similar style. Where can I find hints for typesetting publication standard articles/books as above in TeX. I looked around a bit but couldnt find much from else from keyword searches.  Particularly, I am looking at the chapter headings, title page design, and the mirror effect. Sorry for the title, as I dont really know what its called. How to see python symbolic names of objects on cursor hover of menu items in Blender 2.8 in Blender 2.79 one could hover over a UI element and see the symbolic python name of said element. How would one accomplish the same with Blender >= 2.8? If the earth would stop spinning, what would happen? Sneak Attack has the same type , this is easy, unless there are multiple damage types.  A Flame Tongue does slashing (or piercing) damage, and fire. Can I chose the Sneak Attack damage in this case to be fire too? Why isn't this sudo mv operation with wildcard working? Explicit vs implicit SQL joins Does the logistic map have an attractor for a particular value of the parameter? Background:  Currently I am studying a course on non-linear dynamics. We have been studying about attractors only intuitively, so I do not have a definition for an attractor. Let me give you a couple of examples.  Consider a problem where a ball is slipping in a parabolic valley. It is clear intuitively and quantitatively that the lowermost point of the parabola is the attractor for it.   Say we are talking about a . We may not guess intuitively that there is an attractor, a priori, but using simulations for different values of initial conditions, we may qualitatively (and maybe quantitatively too) compare the trajectories for different initial conditions and convince ourselves that we have an attractor.  Problem:  Consider the  given as   $$x_n = ax_{n-1}{(1-x_{n-1})}.$$  Let us fix a value of the parameter where we "know" that the logistic map exhibits chaos. Say $a=3.9$.  Let us take the definition for the term attractor from :  An attractor is a subset $A$ of the phase space characterized by the following three conditions:   $A$ is forward invariant under $f$: if $a$ is an element of $A$ then so is $f(t,a)$, for all $t &gt; 0$. There exists a neighborhood of $A$, called the basin of attraction for $A$ and denoted $B(A)$, which consists of all points $b$ that "enter $A$ in the limit $t → ∞$". More formally, $B(A)$ is the set of all points $b$ in the phase space with the following property: For any open neighborhood $N$ of $A$, there is a positive constant $T$ such that $f(t,b) ∈ N$ for all real $t &gt; T$. There is no proper subset of $A$ having the first two properties.   How might we demonstrate/convince ourselves of/disprove the statement that the logistic map does have an attractor for a particular choice of the parameter at which the map exhibits chaos? Should one ask generic or specific question? Let's assume that one has some problems with coding or designing specific project. Should one ask general question about techniques, algorithms, generic problem (anonymising the project references), or should one ask about specific problem in specific problem? Or perhaps something in between?  Example:   generic: Cross-browser implementation of “HTTP Streaming” (push) AJAX pattern specific: How to implement AJAX-y 'incremental blame' view in gitweb (git web interface in Perl)?   If one should ask generic questions, how to anonymise problem? If one should ask specific question, how avoid 'homework' syndrome?