Consider two csv files:  $ cat given.csv 123,John 246,Paul 369,George 987,Ringo  $ cat family.csv 246,McCartney 123,Lennon 987,Starr 369,Harrison   Note that the lines are not ordered! How might I use awk, grep, and other bash tools to get a combined output file (order unimportant):  123,John,Lennon 246,Paul,McCartney 369,George,Harrison 987,Ringo,Starr   I was thinking about running a for loop over the first file, then using awk to get the id and then grepping the second file for the relevant record. Is there a more straightforward way to do this in Bash? I find that often bash has  to handle text files that I'm not yet familiar with.
Is it possible to copy the whole rows of File1 in a new File3 following the instruction given by File2 by using a simple bash script using sed or awk?  File1: /*two or more columns*/ AC    456324 DC    689712 GH    123677 KL    236587  File2: /*one column*/ AC DC  File3:  AC    456324 DC    689712   I'm actually performing this using Python dictionaries and I wondered if you knew a simple way out.
FireFox 66 Quantum disabled all my extensions at midnight! Let $f: \mathbb R^2 \to \mathbb R$ defined as   $f(x,y)=(x^2+y^2)\sin(\dfrac{1}{\sqrt{x^2+y^2}})$ if $(x,y) \neq (0,0)$, $f(x,y)=(0,0)$ if $(x,y)=(0,0)$  Prove that $f$ is differentiable at $(0,0)$ but that the partial derivatives of $f$ are not continuous at the origin.  The attempt at a solution:  I had some problems at the first part of the exercise:  I've calculated $\dfrac{\partial f}{\partial x}(0,0)$ and $\dfrac{\partial f}{\partial y}(0,0)$, both exist and are equal to $1$.  So, to prove $f$ is differentiable at the origin, I have to show that   $\lim_{(x,y) \to (0,0)} \dfrac{|f(x,y)-(f(0,0)+&lt;\nabla f(0,0),(x,y)&gt;)|}{\|(x,y)\|}=0$ But $\lim_{(x,y) \to (0,0)} \dfrac{|f(x,y)-(f(0,0)+&lt;\nabla f(0,0),(x,y)&gt;)|}{\|(x,y)\|}$ equals  $\lim_{(x,y) \to (0,0)} \dfrac{|(x^2+y^2)\sin(\dfrac{1}{\sqrt{x^2+y^2}})-(x+y)|}{\|(x,y)\|}$. I don't know how to show this limit equals $0$.  For the second part (I've only analyzed $\dfrac{\partial f}{\partial x}$ since both cases are the same), what I did was try to show that $\lim_{(x,y) \to (0,0)} \dfrac{\partial f}{\partial x}(x,y) \neq \dfrac{\partial f}{\partial x}(0,0)$   I thought of considering the curve $\phi(t)=(t,0)$, so   $\lim_{t \to 0} (f\circ \phi)(t)=\lim_{t \to 0} 2t\sin(|t|^{-1})-\dfrac{t\cos(|t|^{-1})}{|t|^{-1}}$. But $\lim_{t \to 0^{+}} \dfrac{t\cos(|t|^{-1})}{|t|^{-1}}=\lim_{t \to 0^{+}} \cos(\dfrac{1}{t})$ and this limit doesn't exist, so the original limit doesn't exist. This shows the partial derivative with respect to $x$ at the point $(0,0)$ is not continuous.   I would appreciate if someone could help me to finish the first part and tell me if what I did in the second part of the problem is correct. Formulae for Catalan's constant. Some years ago, someone had shown me the formula (1). I have searched for its origin and for a proof. I wasn't able to get true origin of this formula but I was able to find out an elementary proof for it.  Since then, I'm interested in different approaches to find more formulae as (1).  What other formulas similar to ($1$) are known?  Two days ago, reading the book of Lewin "Polylogarithms and Associated Functions" I was able to find out formula (2).  $\displaystyle \dfrac{1}{3}C=\int_0^1 \dfrac{1}{x}\arctan\left(\dfrac{x(1-x)}{2-x}\right)dx\tag1$   $\displaystyle \dfrac{2}{5}C=\int_0^1 \dfrac{1}{x}\arctan\left(\dfrac{\sqrt{5}x(1-x)}{1+\sqrt{5}-\sqrt{5}x}\right)dx-\int_0^1 \dfrac{1}{x}\arctan\left(\dfrac{x(1-x)}{3+\sqrt{5}-x}\right)dx\tag2$   $C$ being the Catalan's constant.  I have a proof for both of these formulae.  My approach relies on the following identity:  For all real $x&gt;1$,  $\displaystyle \int_0^1 \dfrac{1}{t} \arctan \left (\dfrac{t(1-t)}{\frac{x+1}{2}-t}\right) dt=\int_1^{\frac{\sqrt{x}+1}{\sqrt{x}-1}}\dfrac{\log(t)}{1+t^2}dt$ This image is what's supposed to look like in Edit Mode/Object Mode(although I still can make these screenshots even after the update by pressing F12 which is rendering) but the following is what my donut looks like now in Blender.  It shows no shadows and colors. The only thing I did is updating blender to 2.81 from 2.80. And I don't know what but something seems off with blender. Sometimes I can't click any objects so I just pressed tab and then now it's all clickable. Seems like I was in edit mode, but to me, it looked exactly like object mode. I don't know what is wrong with it. How do I make my colors show up again? How are parentheses interpreted at the command line? I guess I'm asking for comments, with subsequent notifications, to be added to queries in SEDE, so we can point out [fixes]  to flawed queries, especially when [the query]  has a comment in it explaining the problem. Prove that there are infinitely many primes and non-primes in the numbers $10^n+1$, where $n$ is a natural number. So numbers are 101, 1001, 10001 etc. Can you get to blocked-in areas? Time indicator is shown as "%a %H:%M" in the center of the top bar.  How do I move it back to the right where it belongs, and make it include the full date and time ("%Y-%m-%d %s %H:%M")? $$\lim_{n\to \infty}\frac1{2n}\log\left({2n \choose n}\right)$$  Now, $\log(n!) = \Theta (n\log(n))$ so I think we could write,   $$\lim_{n\to\infty}\frac{1}{2n}\left(\log\left(2n!\right) - \log\left(n!^2\right)\right) = \frac{1}{2n}\left(\log\left(2n!\right) - 2\log\left(n!\right)\right) $$  $$\lim_{n\to\infty}\frac{1}{2n}\left(2n\log\left(2n\right) - 2n\log\left(n\right)\right) $$  $$\log\left(2n\right) - \log\left(n\right) = \log(2)$$  Is this legitimate? I feel this might be wrong since, the $\Theta$ notation conceals a constant factor. What are Extension Tubes? What are Extension Tubes? I'm stuck in a teleporting loop. What can I do? I set a command block to /tp. It was supposed to activate only if you had 0 time left, and to activate the command block with a hopper clock to keep giving it power.   But it is not checking if you have 0 time left, so it keeps teleporting me. I can't get close enough to the command block to break it, so I'm stuck in a neverending teleport loop.  Any ideas? Traveling Amsterdam-Brussels with KLM ticket on Thalys - When / where does my ticket get stamped? How to emulate titletoc with tocloft I was using titletoc until I realized that it has some incompatibilities with hyperref. The thing is, that titletoc can do the same thing in a easier way, less one.  \titlecontents*{subsection}[5.4em] {\small} {\thecontentslabel~ } {} {} [.~\textbullet\ ] [.]   this part does the subsection as a paragraph (with section number and without page number). I have realized that the problem is the pseudo-code used by tocloft for the entries in the TOC  {\cftXfont {\cftXpresnum SNUM\cftXaftersnum\hfil} \cftXaftersnumb TITLE}% {\cftXleader}{\cftXpagefont PAGE}\cftXafterpnum\par   I mean, the last command \par make impossible to leave two subsection entries in the same textline. Any idea? Another interesting solution is with etoolbox, some examples with that package are awesome, but it's not on my hands.  This is a MWE:  \documentclass{book}  \usepackage{titletoc} \titlecontents*{subsection}[5.4em]{\small} {\thecontentslabel~ }{}{}[.~\textbullet\ ][.]  \begin{document}  \tableofcontents  \chapter{Test Chapter 1} \section{Test Section 1.1} \subsection{First Test Subsection} \subsection{Second Test Subsection} \subsection{Third Test Subsection} \subsection{Fourth Test Subsection} \section{Test Section 1.2} \subsection{First Test Subsection} \subsection{Second Test Subsection}  \chapter{Test Chapter 2} \section{Test Section 2.1} \subsection{First Test Subsection} \subsection{Second Test Subsection} \subsection{Third Test Subsection} \subsection{Fourth Test Subsection} \section{Test Section 2.2} \subsection{First Test Subsection} \subsection{Second Test Subsection}  \end{document} When can I be sure a questionable check has cleared? enumerate in multicols The following image illustrates what am looking for:    Essentially I want the numbering to occur as shown above but using the multicol and enumitem package. But when I try it by using the following code:  \documentclass{article} \usepackage{amsmath,amssymb} \usepackage{enumitem,multicol} \begin{document} \begin{enumerate} \item Evaluate each of the following if $x$ is a non-zero real number.     \begin{multicols}{2}     \begin{enumerate}[itemsep=1cm]% The item sep is my choice here.     \item $\dfrac{|x|}{x}$     \item $\dfrac{x}{|x|}$     \item $\dfrac{|-x|}{-x}$     \item $|x|-|-x|$     \end{enumerate}      \end{multicols} \end{enumerate} \end{document}   I get:    Essentially, I want the (b) to be where the (c) is. I know this has been done but I can't seem to find it. Can you please clarify if it's acceptable to use these terms interchangebly and if not point out to significant differences between these titles. It seems to me that it may be something with scale of an organization (perhaps, small/medium businesses have managing directors, and large corporations have chief executive officers) but I'm not sure. I do understand that a person may bear one or another of these titles formally, but what about real differences? How to change password complexity requirements in Ubuntu 14.04LTS "The antipodal map of $S^2$ is the isometry $\bar m$ sending each point $P$ to its opposite point $-P$" (from textbook)  Show that antipodal points remain antipodal under any isometry of $S^2$. In other words, for each isometry f of $S^2$, if $P$ and $P'$ are antipodal, then so are $f(P)$ and $f(P')$  I am unsure how I can define the $P$ and $P'$ so that they are opposites of each other in the antipodal map, and am I supposed to apply the traditional isometries (translation, reflection and rotation) to the points? I don't understand this problem. I'm curious why PCBs have one square pad in row for 0.1" headers. What is purpose of putting one square pad? What it indicates? Can you push more amps through square pad than round?