I used these commands to allow access to git clone katoolin to be stored in usr  sudo chmod -R 777 /usr/ sudo chown www-data:www-data /usr/   I don't know which one ruined my sudo access. Also, I don't have access to root. I tried entering into recovery mode then into root shell and used commands from  but it didn't work.  Kind of new to it. Some help would be helpful.
I needed to edit a .config file (which I know for a fact is not creating these problems, just to clear that up) and it wouldn't let me save it, so I took ownership of /etc and all contents with the command chown -hR username /etc and that let me edit the .config file but now whenever I try to install any packages or use any sudo commands, it doesn't work  (I've checked for errors in the sudo file in sudoers.d and there was nothing wrong with that).   So how do I return it to the previous owner?
Object appears smoothed after rendering but not in viewport How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code? I'm really new in using biblatex, compile the sample placed in , but what I get is    1.1 Foo    Some text [B02x ].    1.2 Bar    Some text [B02y ].   Do not get the bibliography by chapters, or the global references.  Really not remains to be done   \documentclass{report}  \usepackage[style=alphabetic]{biblatex}  \addbibresource{references.bib}  \begin{document}  \chapter{First chapter}  \section{Foo}  Some text \cite{childs_temperature}.  \printbibliography  \chapter{Second chapter}  \section{Bar}  Some text \cite{hashemian}.  \printbibliography  \newpage  \printbibliography  \end{document}   And the references.bib    @BOOK{childs_temperature,   title = {Practical Temperature Measurement},   publisher = {Butterworth - Heinemann},   year = {2001},   author = {Childs, Peter R N},   address = {Great Britain},   edition = {1},   isbn = {0 7506 5080 X}   }    @PHDTHESIS{hashemian,   author = {Hashemian, Hashem Mehrdad},   title = {Measurements of dynamic temperatures and pressures in nuclear power plants},   school = {{The University of Western Ontario}},   year = {2011},   type = {PhD {T}hesis}   }   I need to obtain references by chapter and global cited references, but i don't know how compile. Category Theory textbook (learning through guided discovery Dummit and Foote) I have already bought the PC version on minecraft for my account. However, when attempting to change my skin, the game simply states:"You have to buy the PC edition of Minecraft."   Which is odd because I already have.  Why is this happening? How can I fix it? How to automate generation of image files? Allow new users to comment for X times in a day While reviewing "First Posts" on Stack Overflow, I often come across new users posting comments as answers. It seems (at least to me) they are not doing this because they are unaware of how Stack Overflow works but because they can't comment on any question they are forced to put it as answer.  I have found duplicate questions for my request like:   ,  and    but the best explanation I have found is an  to .     I think the main reason this isn't supported is there's no way to   downvote comments, which would make them attractive to spammers. If   somebody comments on the top answer in a question the only way to get   rid of it is for six people to flag it. Comment flags don't show up on   10k tools, so it needs to be six people that happen to stumble across   the spam comment, or a moderator that checks the list manually. People   can comment every 15 seconds, so that can get out of hand pretty   quickly. Comments also aren't listed on the user's profile page, so   it's hard to see at a glance if a user has been spamming   So I am suggesting allowing new users (with less than 50 reputation points) to comment only 5 times every day or only 25 times times until they reach 50 reputation points or any other variation of it. I don't really remember the plot but I think the a couple of alien girls (look human) crash land on Earth and are helped by human boy (18-19 ish). They get back to their ship but the older girl, with white hair, decides to stay on Earth to be with the boy.  At the beginning of the TV movie the boy wakes up and uses a ham radio and then goes to work on a ranch/farm(?).  I think it might have been one of these old Disney Sunday night movies. A few months ago I set full disk encryption during installation of Ubuntu 17.10. Now, I've decided to upgrade. The upgrade ran to the end without any problems. However, after reboot I am not able to log into my encrypted disk.  Where can be the problem? I am 100% sure I press the "right keys" on the keyboard, but technically I don't know what I am writing because of "*" characters and maybe after upgrade my keyboard layout changed. I use some characters which might be somewhere else on the keyboard. What language is default after upgrade?   By the way, I've already tried Caps-lock, but still no luck.  Help will be really appreciated. I am not a fan of installing my system and all backups over and over again. How many square meters "twenty feet square" is? One would assume it to be about 2 square meters, but this is obviously not the case. In fact, I'm reading Illium by Dan Simmons. A quote follows:     Much like the room they had faxed into, this space was windowless and about twenty feet square. But unlike the other room, this one was warm, lighted, and free of snow or ice. And unlike the other room, this one was almost filled with an oval metal machine about fifteen feet long.   By this description, "twenty feet square" seems to mean 20x20 feet aka 400 square feet or 40 square meters. Given that Dan Simmons is a renowned American writer, it's not likely that he just can't speak English correctly. So, who's right and who's wrong here? How does one install PlayOnLinux? How do I install PlayOnLinux on Ubuntu? How does \fontsize{}{} work? With the package anyfontsize I can use the command \fontsize{}{}. But the second argument seems to be without any effect. I read  that it is related to the line space. It doesn't work.  \documentclass{article} \usepackage{anyfontsize} \begin{document}  {\fontsize{1cm}{1cm}\selectfont First test : I need to put some text here.}  \bigskip  {\fontsize{1cm}{2cm}\selectfont Second test : I need to put some text here --- does it work?}  \end{document}     Any clue? To evaluate limit of sequence $\left(\left( 1 + \frac1n \right) \left( 1 + \frac2n \right)\cdots\left( 1 + \frac nn \right) \right)^{1/n}$ How do I evaluate the limit of the following sequence $$a_n  = \left(\left( 1 + \frac1n \right) \left( 1 + \frac2n \right)\cdots\left( 1 + \frac nn \right) \right)^{1/n}$$   I tried to take log and then using cauchy $1^{st}$ theorem of limits but I coudn't do it.  Could someone kindly help? Java method dispatch with null argument Why does it (apparently) make a difference whether I pass null as an argument directly, or pass an Object that I assigned the value null?  Object testVal = null; test.foo(testVal);    // dispatched to foo(Object) // test.foo(null);    // compilation problem -&gt; "The method foo(String) is ambiguous"     public void foo(String arg) { // More-specific     System.out.println("foo(String)"); }  public void foo(Object arg) { // Generic     System.out.println("foo(Object)"); }   In other words, why is the (commented-out) second call to foo(...) not dispatched to foo(Object)?  Update: I use Java 1.6. I could compile Hemal's code without problems, but mine still doesn't compile. The only difference I see is that Hemal's methods are static while mine are not. But I really don't see why this should make a difference...?  Update 2: Solved. I had another method foo(Runnable) in my class, so the dispatcher couldn't unambiguously select the single most specific method. (See my comment in Hemal's second answer.) Thanks everyone for your help. How to change from German to English in the File Manager in Ubuntu 15.10? My months and days in my File Manager are in German, how do I change that? On the photo you see 'Dez' : It means Dezember (German for December). I also saw one day Mittwoch (German for Wednesday). How do I change that German issue? This is only my File Manager and not completly but partially. Weird. 2015 Macbook Air screen gradually dimming and dying This is not a problem at booting up. For a couple months now I'll be using my laptop when suddenly the screen dims to about 50% of normal. According to the brightness indicator the brightness is all the way up; I can make it dimmer, but not as bright as normal. The dimming isn't super even either, there are small areas of the screen that seem darker/brighter. In the past the problem easily goes away if I close the lid and reopen it... but now it's happening a lot and sometimes going completely black. Is this an easy/cheap fix? I'm traveling and can't do it myself. Is it worth bringing to the Mac store?  Thanks! Metric is continuous, on the right track? Let $X$ be a metric space with metric $d$. Show that $d:X\times X\rightarrow \mathbb{R}$ is continuous.   The problem is taken from Munkres Topology second edition, Section 20.  I know that if $d$ is a metric on $X$ then $d:X\times X\rightarrow \mathbb{R}$. My thinking is that the topology that is on $X$ is the topology induced by the metric $d$, and that the topology on $X\times X$ is the product topology on that space where we take the basis to be $$\mathcal{B}=\{ U \times V \mid \text{ $U,V$ both open in $X$}\}.$$ Am I on the right track to say that we define some new metric on $X\times X$ and show that this metric induces the same topology as the product topology and then work with the function $d$ as a function between metric spaces to show continuity? The question doesn't mention anything about defining some new metric and I've tried to solve the problem by looking at $X\times X$ as having the product topology, but in picking some point $(x,y) \in X\times X$ and some neighborhood around $d(x,y)$ in $\mathbb{R}$, I haven't yet found the way to make a neighborhood around $(x,y)$ which maps into the neighborhood around $d(x,y)$. Format number to always show 2 decimal places Weird sharp vertices with subdivision modifier I have a simple skull model, to which I applied the subdivision modifier. For the most part everything works as expected, except I keep getting these weird sharp vertices and I can't seem to figure out how to flatten them.    I'm using Blender 2.8. Is this some kind of feature I can disable/enable for particular vertices? The distance between the sharp vertices and the gray outline differ.    Any suggestions please? Thank you!  EDIT: I also tried selecting as both - vertexes and edges and then applied Edge->Clear Sharp, but nothing changed. Incoming light reacts with the several types of cone cells in the eye. In humans, there are three types of cones sensitive to three different spectra, resulting in trichromatic color vision. Each individual cone contains pigments composed of opsin apoprotein, which is covalently linked to either 11-cis-hydroretinal or more rarely 11-cis-dehydroretina.  The opsins (photopigments) present in the L and M cones are encoded on the X chromosome.  A very small percentage of women may have an extra type of color receptor because they have different alleles for the gene for the L opsin on each X chromosome. X chromosome inactivation means that only one opsin is expressed in each cone cell, and some women may therefore show a degree of tetrachromatic color vision. Tetrachromacy is also demonstrated among several species of birds, fish, amphibians, reptiles and insects.  Humans cannot see ultraviolet light directly because the lens of the eye blocks most light in the wavelength range of 300–400 nm.  So, besides above mentioned exceptions, is it possible due to mutations or genetic engineering to see UV or infrared. What kind of mutations should be made or are the changes to be made in the opsines to big to create 'alien' eyes?