What is the difference between .tar.gz and .tar.xz (is there more?)? I know that you can just open up Archive Manager and extract them. But what is the actual difference? Which should I use? What flags should I give tar to extract them in CLI? EDIT: What is the difference between the xz algorithim and the gz algorithim?
Could anyone tell me what is up with so many archives, and how are they differ?  There's at least five that I can think of, .tar.tz, .tar.gz, .tar.bz2, .tar.lz, .tar.z  Which is best for what applications? It just seems silly to make so many variations of the same file but I'm sure there's a reason.
Have you ever had a case where you felt compelled to include strange things like a double that in a sentence? If so, then what did you do to resolve this?  For me, I never knew whether it was acceptable grammar. However, what I did learn was that it was a logic distractor, could lead to confusion, and therefore should be reworded to avoid this. How do I start Nautilus as root? One-sided limits of $f'(x)$ at a point vs. one-sided limits of the difference quotient at that point I know that if a function is piecewise, then when differentiating it one needs to deal separately with the points of intersection of the pieces, because the derivative may not be defined there.  Also, if a one-sided limit of $f'(x)$ at these "crucial points" is infinite or doesn't exist, it doesn't preclude the limit of the difference quotient from existing and being finite. For example, take $f(x)=x^2\sin\frac1x, f(0)=0$: $f'(x)= 2x\sin\frac1x-\sin\frac1x $ has no limit as $x\to0$ but $\lim\limits_{h\to0}\frac{f(h)-f(0)}{h}=0=f'(0)$.  On the contrary, looking at $f(x)=\sin x +\lvert \sin x\rvert $ on $[0,2\pi]$ one has $f'(x)=2\cos x$ on $(0,\pi) $ and $f'(x)=0$ on $(\pi,2\pi)$ so $\lim\limits_{h\to0^+}f'(\pi+h)\ne\lim\limits_{h\to0^-}f'(\pi+h)$, but they are both finite. And in this case it's easy to find that they agree with the one-sided limits of the difference quotient. Why? Does the finiteness of the former imply that they agree with the latter? Is this also true if the one-sided limits of $f'$ at the crucial points agree with each other? Delete all files to which no corresponding file with another extension exists My goal is to find a Linux command sequence, which deletes some files if a special condition is fulfilled:  All files with the extensions .cut or .cut.bak in the current directory shall be removed, IF there is no file having the same name, but extension .rec or .mpg in the current directory.  Background: I am developing a tool for a Linux-based PVR, that allows cutting of recorded programs. For each recording (extension .rec or .mpg) the segment markers are stored in a .cut-file with the same name. When some recording gets moved/renamed/deleted, then the corresponding cut-file remains orphaned and shall be deleted. I already have implemented the removing of those useless cut-files in C. But I am wondering, whether there may be a (simple) system based solution. In this case it could be run via 'system' and &amp; in the background, which would make my application more responsive...  I already asked a similar question for the recursive case (browsing also into subdirectories), . There has been a (nearly) perfect answer by kos - but unfortunately it removes too many files, so it is not usable, and I was not able to figure it out... But the same idea can be used here, IF it is possible to parse and pipe the result of 'ls' linewise... Here is my candidate for  the most elementary proof that $\lim_{n \to \infty}(1+1/n)^n $ exists. I would be interested in seeing others.  $***$ Added after some comments: I prove here by very elementary means that the limit exists. Calling the limit "$e$" names it. $***$  It only needs Bernoulli's inequality (BI) in the form $(1+x)^n \ge 1+nx$ for $x &gt; -1$ and $n$ a positive integer, with equality only if $x = 0$ or $n = 1$. This is easily proved by induction: It is true for $n=1$, and $(1+x)^{n+1} = (1+x)(1+x)^n \ge (1+x)(1+nx) = 1+(n+1)x+nx^2 \ge 1+(n+1)x $. (If $-1 &lt; x &lt; 0$, if $1+nx \ge 0$, the above proof goes through, and if $1+nx &lt; 0$, $1+mx &lt; 0$ for all $m \ge n$ so certainly $(1+x)^m &gt; 1+mx$.)  This proof originally appeared in N.S Mendelsohn, An application of a famous inequality, Amer. Math. Monthly 58 (1951), 563 and uses the arithmetic-geometric mean inequality (AGMI) in the form $\big(\sum_{i=1}^n v_i/n\big)^n \ge \prod_{i=1}^n v_i$  (all $v_i$ positive) with equality if and only if all the $v_i$ are equal.  Let $a_n = (1+1/n)^n$ and $b_n = (1+1/n)^{n+1}$.  We will prove that $a_n$ is an increasing sequence  and $b_n$ is an decreasing sequence.  Since $a_n &lt; b_n$, this implies,  for any positive integers $n$ and $m$ with $m &lt; n$  that $a_m &lt; a_n &lt; b_n &lt; b_m$.  For $a_n$, consider n values of $1+1/n$ and $1$ value of $1$.  Since their sum is $n+2$ and their product is $(1+1/n)^n$, by the AGMI,  $((n+2)/(n+1))^{n+1} &gt; (1+1/n)^n$,  or $(1+1/(n+1))^{n+1} &gt; (1+1/n)^n$,  or $a_{n+1} &gt; a_n$.  For $b_n$, consider $n$ values of $1-1/n$ and $1$ value of $1$.  Since their sum is $n$ and their product is $(1-1/n)^n$, by the AGMI,  $(n/(n+1))^{n+1} &gt; (1-1/n)^n$  or $(1+1/n)^{n+1} &lt; (1+1/(n-1))^n$,  or $b_n &gt; b_{n+1}$.  Since $b_n-a_n  = (1+1/n)^{n+1} - (1+1/n)^n = (1+1/n)^n(1/n) =a_n/n $ and every $a_n$ is less than any $b_n$ and $b_3 = (1+1/3)^4 = 256/81 &lt; 4$, $b_n-a_n &lt; 4/n$, so $b_n$ and $a_n$ converge to a common limit.  These proofs do not seem to be really elementary,  since they use the AGMI.  However, they use a special form of the AGMI,  where all but one of the values are the same,  and this will now be shown to be implied by BI,  and thus be truly elementary.   Suppose we have $n-1$ values of $u$ and $1$ value of $v$ with $u$ and $v$ positive.  The AGMI for these values is  $(((n-1)u+v)/n)^n \ge u^{n-1}v$  with equality if and only if $u = v$.  We will now show that this is implied by BI: $(((n-1)u+v)/n)^n \ge u^{n-1}v$  is the same as  $(u+(v-u)/n)^n \ge u^n(v/u)$.  Dividing by $u^n$,  this is equivalent to  $(1+(v/u-1)/n)^n \ge v/u$.  By BI,  since $(v/u-1)/n &gt; -1/n &gt; -1$, $(1+(v/u-1)/n)^n \ge 1+n((v/u-1)/n) = v/u$  with equality only if $n=1$ or $v/u-1 = 0$. Thus BI implies this version of the AGMI. Why is Git not found after installing OS X Lion? Rotate touchscreen and disable the touchpad on Yoga 2 Pro in rotated mode On my Lenovo Yoga 2 pro I installed Ubuntu 14.04 32bit and kept the installed Windows 8 on another partition.  In Windows, When you turn it into tablet mode, the keyboard and touchpad turns off so you don't accidently click on it at the back of the "tablet".  In ubuntu 14.04 only the keyboard turns off, but the touchpad stays active. Not even the Fn+F6 combination doesn't turn it off.  So far I can only disable it with  synclient TouchpadOff=1   (and re-enable with 0)  I tried xev to get the keycode for Fn+F6 but pressing this combo generates no output. Turning the monitor to the back neither.  How can I disable the touchpad automatically when I rotate or turn the monitor on the back, and re-enable the Fn+F6 Hotkey?      UPDATE: After some weeks sudo apt-get upgrade Fn+F6 is working now, so there is only the question how to rotate the screen and how to disable the touchpad automatically when rotating the screen. Is it acceptable to change the vid column of a term programmatically in the database? I need to move some terms from one vocabulary to another by retaining all their data: translations, aliases, and node references.  Is it acceptable to change its vid column value directly in the database? The terms don't have hierarchy relationships which needs to be handled. CNAME for top of domain? Is it possible to set a CNAME record at the top of a domain? (i.e. @ CNAME www, @ CNAME foobar.com., etc.)  My ISP says that it's only possible to use CNAME's for subdomains but I've read somewhere else that is should be possible even if not recommended. What software to cite in a manuscript, and how? When writing a manuscript for a scientific article, I often wonder what software I should cite or acknowledge, and how.  The first problem is to make a choice which software to cite. On the one hand, there is no way to cite all software, as this would mean to cite my whole software stack (Linux, GNU tools, emacs, git, ...). On the other hand, not citing any software is not fair, either. Furthermore, some software explicitly asks to be cited, some software doesn't. Also, some software is really crucial to the results, some isn't. Another important aspect is that citing software is not only about giving credit to the authors of the software, but also to give other scientists hints on what software they might want to use. So, the choice which software to cite is a problem.  The second problem is how to cite the software. Some (scientific) software does provide a classical scientific article that can be cited. However, in this case, no URL to the software is given. Others do not have an associated article. How do I cite these? I have seen people that cite the manual of a software, others just give the URL. What is the way to go?  Another aspect is where to cite the software. Some software can be cited in the course of the articles text, but when it comes to more fundamental software, other places may be more appropriate.  Are there any good ideas out there on any of these aspects? Plugin or brush for transforming a photo to a fractal in gimp? Folks,  I've been looking all over for a plugin or brush that will help me take a photo and reduce it to that 'electric look' (or fractal?) that i'm seeing in various places. I'd vastly prefer one for Gimp.  Does anyone know how these are being done? I'm seening references to fractalius for photoshop, but what about gimp?  Examples: How might I schedule a C# Windows Service to perform a task daily? I have a service written in C# (.NET 1.1) and want it to perform some cleanup actions at midnight every night. I have to keep all code contained within the service, so what's the easiest way to accomplish this? Use of Thread.Sleep() and checking for the time rolling over? Say I want to book a flight from Fort Lauderdale to Chicago.  Say the airline also flies to St. Louis from Fort Launderdale but has a connecting flight through Chicago.  If I book that flights from FLL->ORD->STL and just get off in Chicago, what possible problems can I run into, assuming I didn't check any bags and only have carry on?  This scenario exist for Southwest, but I wanted this be more of a general question that would apply to all airlines. problems using apa6e with biblatex-apa As in  I'm trying to use apa6e and biblatex-apa together and having problems.  Before I arrived at these problems, over the course of many hours of much reading, I first managed to get BibTeX working as expected in a simple input file (by modifying sample2e.tex). Then I managed to get apa6e working as expected based on the author's example in apa6e.pdf (which uses apacite). But when I try to get apa6e working with biblatex-apa, I end up with problems.  Here's my input file:  \documentclass{apa6e}  \usepackage[american]{babel} \usepackage{csquotes}  % biblatex \usepackage[style=apa]{biblatex} \bibliography{biblatex-apa-test-references}  \title{An Example Document} \shorttitle{Psychology: the end} \author{Silly Name}  \authornote{\dots} \abstract{\dots}  \begin{document}  \maketitle  This is an example input\cite{7.01:2} file.  Comparing it with the output it generates can show you\cite{7.01:3a} how to produce a simple document of your own.  \printbibliography  \end{document}   Attempting to typeset this in TeXShop by running LaTeX, then BiBTeX (which based on console messages, does seem to correctly call biblatex rather than BiBTeX), then LaTeX again, I get the following error message which I am having great difficulty (no doubt due to my lack of experience with TeX and co.) decoding.  (./test6.aux) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ptm.fd) *geometry* driver: auto-detecting *geometry* detected driver: pdftex (./test6.bbl) Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Silly Name   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Author Note  [1{/usr/local/texlive/2011/texmf-var/fonts/map/pdftex/updmap/pdftex.map}] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Abstract  [2] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 25--25  []\OT1/ptm/b/n/12 References  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra  (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1pcr.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omlztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omsztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omxztmcm.fd) Overfull \hbox (8.03372pt too wide) in paragraph at lines 25--25 [][]  \OT1/ptm/m/n/12 Gilbert, D. G., Mc-Cler-non, J. F., Ra-bi-novich, N. E.,  Sugai, C., Plath, L. C., As-gaard, G., ... Botros,  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra                                    {year}{month}{day}\iffieldundef {endyear}{... l.25   I tried many different sources in several different *.bib files before eventually trying the .bib database shown above and included with biblatex-apa. All trials gave a similar error.  Can someone help? I'm impressed that the poster above was able to do anything with apa6e and biblatex-apa, and if I only had her problem of having the reference page title show up in bold, I'd be really happy.  If you need to know, my tools are from a fresh installation of MacTeX that I immediately updated using the TeX Live Utility. I've checked my versions for apa6e (v0.3) and biblatex-apa (v4.2), and I think these are current. Comparing two integers without any comparison Is it possible to find the greatest of two integers without any comparison? I found some  solutions:   if(!(a/b)) // if a is less than b then division result will be zero. {     cout &lt;&lt; " b is greater than a"; } else if (!(a-b)) // we know a is greater than or equal to b now.  check whether they are equal. {     cout &lt;&lt; "a and b are equal"; } else     cout &lt;&lt; "a is greater than b";   But if(c) or if(!c) is a comparison to zero. In addition it doesn't work for negative numbers. In fact I need a solution that avoids any if statement. Instead I should use switch statements and arithmetic operators. ThanX. How to make a file executable? How can I make my file so that I can double click on it, and it runs. It is a .sh script, but I also have files that say:  executable (application/x-executable)  in the description of what they are.  I can't run any of these from terminal, or by double clicking.  If possible, I would like a way using either the GUI or a Terminal, but not a combination of the two.  Here is a screenshot of what I see when I right click then go on properties. The file first:    And the shell script here:    NB: I accept that this is a duplicate (I was looking for it, and couldn't find it, so asked + answered it, hoping that I would find it) however, I don't think the question about .desktop files is a duplicate. Calculate the uncertainty in velocity of electron I got this question in one of my periodic test in coaching, I (seemingly) solved the question but later recognised what mess I did.  So, the question is :      Calculate the uncertainty in velocity of an electron. If the uncertainty in its position is ${10^ {-15}} \; \mathrm m$.   By simple calculations one can see that the answer would be ${5.79\times{10^{10}}} \; \mathrm{m/s}$. However, as one can see, the uncertainty in velocity is greater than the velocity of light then how is that possible or there is some other way to handle such problems.  P.S. I know the concept of dynamic mass but I am not very familiar with it. (I think that would work here, but don't know how?) How do I get started playing Dungeons and Dragons 4th edition by myself? I've been wanting to start playing D&amp;D for some time, and I was wondering how I could get started by myself with relative ease. I own the first two player handbooks, and a set of dice. scanf() misbehaving Why does cancellation of dots $\frac{\partial \dot{\mathbf{r}}_i}{\partial \dot{q}_j} = \frac{\partial \mathbf{r}_i}{\partial q_j}$ work?