Help choosing a version
How do I find out which version and derivative of Ubuntu is right for my hardware in terms of minimal system requirements?
Working in Cycles.  Say I have a "disco ball" with a glossy shader. I'm pointing a spot light to it, and I'm trying to have the reflections of that light illuminate the diffuse material on the walls with the patterns from the ball.    I get this:    but I'd like to get something like:    For the illustration I placed a point light inside the ball an removed faces. But what I'd like to do is move the light around the ball so that the light reflected from it changes like it would do in real life.   Is that possible at this point?  EDIT:  Just for the record here's the image rendered in LuxRender (yet another program to learn...) Can I hire my kid and start a Roth IRA for him? I own an LLC, of which I am currently the sole member. It's my main source of income.  I am wondering if there is a reason why I could not do the following:   Hire my child as a part-time employee of the LLC, for an annual salary of $5500. Start a Roth IRA for the kid and put the $5500 into it. Deduct the $5500 as a payroll expense for my LLC, thereby reducing my amount of taxable income.   To me, this seems attractive because I'd lower my LLC's tax liability. Meanwhile, my kid would not have to pay any taxes on the $5500 because it is lower than the standard deduction. And by putting the money in a Roth IRA, he'd get an investment that would grow tax-free. It would essentially be like getting the pre-tax benefits of a traditional IRA with the post-tax benefits of a Roth.  The way I see it, I'd win, my kid would win and the IRS would lose, for once.  Is there any reason this wouldn't work? There is no minimum age or income for contributing to a Roth IRA. So as long as I could legally hire my kid, I don't see any obstacles. How does Ubuntu partition the disk when we choose "Erase disk and install Ubuntu" during installation? Till today I was using ubuntu 13.04 in my windows7/ubuntu dual boot. Just now I have upgraded to ubuntu 14.04. My software updater showed an updates available message. I proceeded with  Install Now . Soon I got the following window.    Then I tried sudo apt-get clean as recommended. Nothing happened! Not even a window opened. Teach me deleting the temporary packages.   Deleting temporary files may not be highly helpful in case of further updates and installs for I don't have too much space left in my /. I wanna extend my / partition with the help of the unallocated space in my HD. The following is my Gparted window.       I got an answer . But it wasn't useful for me. I had two choices. But the answer wasn't working for both my chioces.  Choice 1: I may use the 4.25 GiB unallocated space to extend my /dev/sda10. To do so, I must need to move my linux-swap partition. But my Resize/Move option is disabled for the linux-swap partition. Choice 1 failed!   Choice 2: I may use the 14.35 GiB unallocated space instead. In this case I must move more than one partition. /dev/sda4  partition is the first on the list. Even that partition has the same problem. Resize/Move option is disabled. Choice 2 failed!  I am out of choices now.  What shall I do? Help me to extend my / with Gparted. When traveling to a country with a different currency, how should you take your money? I'm trying to run multiple Nodejs applications on Nginx server running on CentOS 7. I noticed that when I run a Nodejs app on some ports I get an 502 Bad Gateway error in the browser so I checked the error logs:  [notice] 12806#0: signal process started [crit] 12807#0: *13 connect() to 127.0.0.1:7777 failed (13: Permission denied) while connecting to upstream, client: **.**.99.58, server: myapp.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:7777/", host: "myapp.com" [crit] 12807#0: *13 connect() to [::1]:7777 failed (13: Permission denied) while connecting to upstream, client: **.**.99.58, server: myapp.com, request: "GET / HTTP/1.1", upstream: "http://[::1]:7777/", host: "myapp.com"   when I change the app to listen to 8008 for example everything is working fine. I checked permissions and if the process is running as root and everything seems ok. I played with the timeouts as well but no result. Can anyone help? How to convert Bedrock texture pack to Java Edition Minecraft Why doesn't hydrogen gas exist in Earth's atmosphere? The root mean square velocity of hydrogen gas at room temperature is: Gas constant: $R=8.31\ \mathrm{J\ K^{-1}\ mol^{-1}}$ Molar mass of hydrogen gas: $M=2.02\times10^{-3}\ \mathrm{kg/mol}$ $$\begin{align} v &amp;= \left(\frac{3\times8.31\ \mathrm{J\ K^{-1}\ mol^{-1}}\times300}{2.02\times10^{-3}\ \mathrm{kg/mol}}\right)^{\frac12}\\ &amp;= 3356.8377\ \mathrm{m/s}\\ &amp;= 3.356\ \mathrm{km/s} \end{align}$$ The escape speed of Earth is $11.2\ \mathrm{km/s}$, which is larger than the root mean square velocity of hydrogen gas. But still, hydrogen gas doesn't exist in Earth's atmosphere. Why? Have I made any mistakes in my calculations? Let $X$ be an arbitrary random variable  takes values in $\{0,1,2,...,10\}$. What are the minimum and  maximum values of variance of random variable $X$? Where is the pet store? I was playing sims freeplay on my iPod yesterday but could not find the pet store. Where is the pet store in the preteens are here update? To be specific, I have an event table that logs when a user joins or leaves a team.  It looks something like the following:  ------------------------------------- | user | event  | team | timestamp | ------------------------------------- | A    | joined | 1    | 2016-1-1  | | B    | joined | 1    | 2016-1-1  | | C    | left   | 1    | 2016-1-1  | | C    | joined | 2    | 2016-1-1  | | A    | left   | 1    | 2016-1-2  | | A    | joined | 2    | 2016-1-2  | | B    | left   | 1    | 2016-1-3  | | A    | left   | 2    | 2016-1-3  | -------------------------------------   I need to restructure this in a view to look something like the following  -------------------------------------- | user | team | joined    | left     | -------------------------------------- | A    | 1    | 2016-1-1  | 2016-1-2 | | A    | 2    | 2016-1-2  | 2016-1-3 | | B    | 1    | 2016-1-1  | 2016-1-3 | | C    | 1    | null      | 2016-1-1 | | C    | 2    | 2016-1-1  | null     | --------------------------------------   How can I achieve this?  For more detail, I'm attempting to do this in Amazon Redshift (PostgreSQL) How to prove that a number is irrational Enable USB debugging (under settings/applications/development) programmatically from within an app Explanation for "emails"? I would like to be able to write a Java class in one package which can access non-public methods of a class in another package without having to make it a subclass of the other class. Is this possible? Taking Seats on a Plane TikZ: multiple decorations on a path. How do I make Git use the editor of my choice for commits? Grep: unexpected results when searching for words in heading from man page I'm running into weird behavior when trying to grep a man page on macOS. For example, the Bash man page clearly has an occurrence of the string NAME:  $ man bash | head -5 | tail -1 NAME   And if I grep for name I do get results, but if I grep for NAME I don't:  $ man bash | grep 'NAME' $ man bash | grep NAME   I've tried other uppercase words that I know are in there, and searching for SHELL yields nothing whereas searching for BASH yields results.  What's going on here?  Update: Thanks for all the answers! I thought it worth adding the context in which I ran into this. I wanted to write a bash function to wrap man and in cases where I've tried to look up the man page for a shell builtin, jump to the relevant section of the Bash man page. There might be a better way, but here's what I've got currently:  man () {   case "$(type -t "$1")" in     builtin)       local pattern="^ *$1"        if bashdoc_match "$pattern \+[-[]"; then         command man bash | less --pattern="$pattern +[-[]"       elif bashdoc_match "$pattern\b"; then         command man bash | less --pattern="$pattern[[:&gt;:]]"       else         command man bash       fi       ;;     keyword)       command man bash | less --hilite-search --pattern='^SHELL GRAMMAR$'       ;;     *)       command man "$@"       ;;   esac }  bashdoc_match() {   command man bash | col -b | grep -l "$1" &gt; /dev/null } How to draw density estimate on histogram by pgfplots? I know how to draw a density histogram using pgfplots from this answer: .  But how can I draw an estimate line on the histogram like this?    \documentclass{article} \usepackage{pgfplots} \begin{document} \pgfplotsset{     small,     every axis plot post/.style={         fill=orange!75,         draw=orange!50!black     },     trim axis left }  \begin{tikzpicture} \begin{axis}[ymin=0, title=\texttt{hist=density}] \addplot [hist=density] table [y index=0] {random.txt}; \end{axis} \end{tikzpicture} \end{document}