How to grep for two words with a tab in between them
Why does my grep expression need to use $'string' to match tab characters?
Ubuntu in VirtualBox wants to install on every boot I have installed Ubuntu 11.10 using Virtual Box in my Windows XP. I have use Ubuntu 11.10 iso to install it. First time when I installed every thing was fine but when I shutdown the VirtualBox and start Ubuntu again, it asks me to install Ubuntu and try Ubuntu without installing.  Do I need to do some extra settings? What is the difference between "speaking" and "talking"? It seems more politically correct to say that someone is speaking rather than talking.  What is the definitive difference between these terms? Use of very as an adjective is (in my experience) most frequently attested in phrases like     ...the very person I was looking for.   To use adjective very with the indefinite article sounds quite bizarre in this case:     ?...a very person I was looking for.   But consider this sentence, where indefinite a is used:     Visualizing a very transformation of the master-slave relation, Thomas presses further: the slave is brother to the master, even doubly a brother.   OED treats the two uses as separate senses of the word, with the following definitions:           (first use):&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;With limitation (usually expressed by the or a possessive) to particular instances      (second use): Really or truly entitled to the name or designation   Here are two respective examples quoted in OED:     What would you say to me now, and I were your verie, verie Rosalind? (1616)   Thence we went into Queen Mary's room, and saw that beautiful portrait—that very queen and very woman. (1857)   Clearly, the difference in meaning between the two senses is quite light, and it seems to me like a kind of difference which is recurrent enough to have its own term. What is the proper term? Are there other English words having similarly related pairs of senses? And lastly, is OED jumping the gun in treating these as two senses? Could the difference in meaning instead be due to the choice of determiner? What does '>/dev/null 2>&1' mean in this article of crontab basics? Exclamation(!) turned in to question mark(?) in title field I just submitted a question () with an exclamation (!) at the end of the title (with one space between the word and the exclamation) but it turned in to question mark (?).   I removed the space between the word and the exclamation, then it shows normal.   Is this an intended feature? How do I tell if matrices are similar? Does Wasserstein distance require the source and target distributions to have the same mass? If we minimize the Wasserstein loss, $$W_1 (P_S, P_T) = \underset{\gamma \in \Pi}{\text{min }} \sum_{x,y} |x-y|\gamma(x,y)$$ which means we are looking for the coupling $\gamma(x,y)$ that minimizes the cost of moving mass from the source distribution $P_S$ to the target distribution $P_T$,  Do the masses of the source and target distributions have to be identical? If so or not, how are the masses of $P_T$ and $P_S$ accounted for mathematically in, or when minimizing, the shown formula, or what might be missing/overlooked by the Wasserstein approach overall due to the mass differences? Preventing brute force attacks against ssh? What tool or technique do you use to prevent brute force attacks against your ssh port. I noticed in my Security logs, that I have millions of attempts to login as various users through ssh.  This is on a FreeBSD box, but I imagine it would be applicable anywhere. Find all the values of $w$ ∈ C that satisfy the equation. Are there any more Asgardians? Create a Symbolic link to the merged contents of 3 folders I have 3 folders with large amount of data in each which has to be maintained seperately. Can I create a sym link or shortcut.in windows which should show me the merged contents of the 3 folders. I am not looking for library conf in Win7.   Any suggestion is highly appreciated. Editable fields in views I have noticed that such terms as model hyperparameter and model parameter have been used interchangeably on the web without prior clarification. I think this is incorrect and needs explanation. Consider a machine learning model, an SVM/NN/NB based classificator or image recognizer, just anything that first springs to mind.   What are the hyperparameters and parameters of the model? Give your examples please. What does a wizard do to cast a spell which contains a DF component? Take  for example,  Components V, S, DF    A divine focus component is an item of spiritual significance. The divine focus for a cleric or a paladin is a holy symbol appropriate to the character's faith. The divine focus for a druid or a ranger is a sprig of holly, or some other sacred plant. If the Components line includes F/DF or M/DF, the arcane version of the spell has a focus component or a material component (the abbreviation before the slash) and the divine version has a divine focus component (the abbreviation after the slash).  So do wizards have holy/unholy symbols in their spell components pouch or what? Why does C++ not let baseclasses implement a derived class' inherited interface? How can I set up dual monitors with nVidia? I always thought water sources were called taps in kitchens, bathrooms etc, but a Google search only returned outdoor taps.  So my question is, what are indoor taps really called? Like this one: The following MWE compiles (for me)  \documentclass{article}  \usepackage{pgfplots} \pgfplotsset{compat=newest} \usetikzlibrary{external} \tikzexternalize[prefix=figures/externalized/]   \begin{document} \begin{figure}     \centering     \begin{tikzpicture}          \begin{axis}  %           \addplot3[surf,mesh/rows=129,mesh/cols=129,mesh/ordering=y varies] table[x=X,y=Y,z=psi] {figures/data/LidDrivenCavity/Lid_SPIKE_128x128_Re1000_psi.dat};              \addplot3[contour gnuplot,mesh/rows=129,mesh/cols=129,mesh/ordering=y varies] table[x=X,y=Y,z=psi] {figures/data/LidDrivenCavity/Lid_SPIKE_128x128_Re1000_psi.dat};          \end{axis}      \end{tikzpicture}     \caption{ciao} \end{figure} \end{document}   where the data file is . If I de-comment the first \addplot3 and comment the second one, then I get an error. The final part of the log file (the interesting one, I think) is  ===== 'mode=convert with system call': Invoking 'pdflatex -shell-escape -halt-o n-error -interaction=batchmode -jobname "figures/externalized/prova-figure0" "\ def\tikzexternalrealjob{prova}\input{prova}"' ======== \openout3 = `prova.auxlock'.  runsystem(pdflatex -shell-escape -halt-on-error -interaction=batchmode -jobname  "figures/externalized/prova-figure0" "\def\tikzexternalrealjob{prova}\input{pr ova}")...executed.  \openout3 = `prova.auxlock'.   ./prova.tex:22: Package tikz Error: Sorry, the system call 'pdflatex -shell-esc ape -halt-on-error -interaction=batchmode -jobname "figures/externalized/prova- figure0" "\def\tikzexternalrealjob{prova}\input{prova}"' did NOT result in a us able output file 'figures/externalized/prova-figure0' (expected one of .pdf:.jp g:.jpeg:.png:). Please verify that you have enabled system calls. For pdflatex,  this is 'pdflatex -shell-escape'. Sometimes it is also named 'write 18' or som ething like that. Or maybe the command simply failed? Error messages can be fou nd in 'figures/externalized/prova-figure0.log'. If you continue now, I'll try t o typeset the picture.  See the tikz package documentation for explanation. Type  H &lt;return&gt;  for immediate help.  ...                                                l.22    \end{tikzpicture}  ?  PGFPlots: reading {figures/data/LidDrivenCavity/Lid_SPIKE_128x128_Re1000_psi.da t} Runaway argument? {\pgfkeyssetvalue {/pgfplots/execute at begin plot visualization}{}\pgfkeyssetv alue \ETC. ./prova.tex:22: TeX capacity exceeded, sorry [main memory size=5000000]. &lt;argument&gt; ...5e-1],2Y7.753628e-3]}{2Y8.20894\ETC.  l.22    \end{tikzpicture}  If you really absolutely need more capacity, you can ask a wizard to enlarge me.   Here is how much of TeX's memory you used:  20761 strings out of 493054  547383 string characters out of 6134761  5000001 words of memory out of 5000000  23958 multiletter control sequences out of 15000+600000  3640 words of font info for 14 fonts, out of 8000000 for 9000  1141 hyphenation exceptions out of 8191  62i,4n,84p,728b,1519s stack positions out of 5000i,500n,10000p,200000b,80000s ./prova.tex:22:  ==&gt; Fatal error occurred, no output PDF file produced!   similar (or the same) error appears if externalization is not enabled/used.  My TeX distribution is TeX Live on Mac OS X 10.9.5 and I use TeXShop as editor.  Once I (partially) solved a  on Windows+MikTeX+TeXniccenter by modifying/adding options to the command executed when compile button is pressed. I say partially since I actually solved the problem for some data file. Then I experienced the same problem with larger datafile and/or different plots (I don't remember anymore) and didn't find a way out, no matter how much I extended the memory.  What should I do now? Show that there is no epimorphism from ($\mathbb{Q}$, +) to ($\mathbb{Z}$, +) Index of the center of a group in the group is not a prime number The question is to prove index of $Z(G)$ in $G$ is not a prime number.    We know that $|G:Z(G)|=|G:C_G (x)||C_G (x):Z(G)|$ where $C_G (x)$ means centralizer of $x \in G$  I want to mention that we do not want to use $G⁄Z(G)$ theorem.   We may assume that $|G:Z(G)|=p$ where $p$ is a prime.