Was messing around with an external drive and wanted to change the permissions of a folder. However, I accidentally ran sudo chown myuser -r /. I have never felt so dumb in my life. I immediately realised what I had done and canceled it, but it was too late.  I'm on Arch. How screwed am I. Is this fixable or is it a lesson to be remembered?  Kids this is why you don't mess with recursive commands when sleepy :(.
If I run:  sudo chown -R user:user /   Can I revert it to what it was before I ran it?
Flight ticket reimbursement after Travel Warning I've got a round-trip flight with Royal Air Maroc from Strasbourg, France (SXB) to Ouagadougou, Burkina Faso (OUA) on Monday, Nov 10. Return is on Dec 1. The recent turmoils in Ouagadougou have led the US Department of State for Travels to issue a , which is why I'd like to refrain from the trip.  Any chance I can get a reimbursement for my tickets? In Germany (where I live), an official travel warning can help you get a refund when you book a trip with a tour operator/travel agency, but in this case I booked the flight directly with a non-German airline, so German law surely doesn't apply here.  EDIT: Sorry for failing to state this earlier, but I had already called the airline as suggested in the answers. They had told me it's not possible to get a refund with my standard fare. However, I understand that sometimes you really have to bargain to get a refund, so I wanted to learn about similar experiences and possibly about some hard (legal) facts that I could bring forward. Finding the confidence level and number of successes? Given that the sample size is $1500$ and the confidence interval of $p$ is $(0.050, 0.083)$. Find the confidence level and the number of successes.  I have so far that $E=Z_{1-\alpha/2}∗\sqrt{(p∗({p-1}))/n}$   Where $p$ is the center of the given interval, so $p = (0.050+0.083)/2 = 0.0665$  Also, the error $E$ as the difference of the midpoint and the endpoint of the interval so $E=0.0665-0.050=0.0165$   Plugging this into the equation I got that  $0.0165=Z_{1-\alpha/2}*\sqrt{((0.0665)(1-0.0665))/1500}$   Solving for $Z_{1-\alpha/2}$ gives $Z_{1-\alpha/2}=2.56$ and since $Z_{2.96} = 0.99$   $Z_{1-\alpha/2} = 0.01$  Is what I have so far right? If so, how do I find the number of successes? Is it just to multiply 0.99 by the number of trials?   So that way I would get $1500*0.99=1485$ ? Fermions, different species and (anti-)commutation rules My question is straightforward:  Do fermionic operators associated to different species commute or anticommute? Even if these operators have different quantum numbers? How can one prove this fact in a general QFT? Why does parameter expansion with spaces without quotes work inside double brackets "[[" but not inside single brackets "["? I'm confused with using single or double brackets. Look at this code:  dir="/home/mazimi/VirtualBox VMs"  if [[ -d ${dir} ]]; then     echo "yep" fi   It works perfectly although the string contains a space. But when I change it to single bracket:  dir="/home/mazimi/VirtualBox VMs"  if [ -d ${dir} ]; then     echo "yep" fi   It says:  ./script.sh: line 5: [: /home/mazimi/VirtualBox: binary operator expected   When I change it to:  dir="/home/mazimi/VirtualBox VMs"  if [ -d "${dir}" ]; then     echo "yep" fi   It works fine. Can someone explain what is happening? When should I assign double quotes around variables like "${var}" to prevent problems caused by spaces? If I design a PC for use as an NPC, how much XP should he give when killed? Biblatex with Biber: Configuring my editor to avoid undefined citations Running the minimal example  \documentclass{article} \usepackage{filecontents} \begin{filecontents*}{\jobname.bib} @ARTICLE{example,   author  = {Other, Anthony Norman},   title   = {Some things I did},   year    = {2014},   journal = {J.~Irrep. Res.},   volume  = {1},   number  = {1},   pages   = {1-10} } \end{filecontents*} \usepackage[backend=biber]{biblatex} \addbibresource{\jobname.bib} \begin{document} Hello\cite{example}. \printbibliography \end{document}   I get the warning There were undefined references.  I have read  and know that I need to run:   LaTeX Biber LaTeX   However, my editor is only set up to run BibTeX. How do I go about setting up my editor/IDE to be able to run Biber, and how do I run the LaTeX/Biber/LaTeX cycle?  Answers (sorted alphabetically by editor name)                    Answer guidelines   Each answer should be for one editor. If the editor is cross-platform, if possible give a single answer with notes covering the minor platform variations. Please edit the question to include new answers in the 'link list' Each answer should be 'stand alone', i.e. don't say 'It's almost the same as editor Y but ...' for the editor part Instructions for 'build tools' such as arara or latexmk are welcome but should explain how to set up the editor in question as not all editors allow simple addition of arbitrary tools Prevent direct access to a php include file I have a php file which I will be using as exclusively as an include. Therefore I would like to throw an error instead of executing it when it's accessed directly by typing in the URL instead of being included.  Basically I need to do a check as follows in the php file:  if ( $REQUEST_URL == $URL_OF_CURRENT_PAGE ) die ("Direct access not premitted");   Is there an easy way to do this? I've had my HTC Desire for a couple of months now and it is awesome! (A huge improvement to my previous phone... Nokia 3315)  Though recently, I've realised that the phone semi-freezes more and more often - ie. when swiping between homescreens it will either pause/freeze and I will have to re-swipe to get it to change screens. Or worse, it just won't respond to any further swipes and I have to lock the screen then unlock to get the phone back into action.  Got quite annoyed at this (was probably happening once or twice a day) so I thought it might help to turn it off and on again. So I did - not sure if it was a placebo effect but it seems to have helped a bit?  So given that this is my first smartphone, I was wondering if it is 'normal' to need to restart the phone every so often. If so, how often is 'normal'? If not, what can I do to diagnose/fix this problem? Questions with no close votes appearing in the close vote queue? I've just been offered the wonderful opportunity to review .        ... but on closer inspection ?        Is this  (e.g I'm assuming this post did previous have a close vote, but has now aged away in ways I don't understand), or should questions with no active close votes be removed from the queue.  p.s. If it's , please expect my  asking for this not to be the case ;). How to remove the "No front page content has been created yet." message from the front page? I only want blocks on the homepage. Because I don't have any nodes, and I want to keep the homepage as /node I am getting a "No front page content has been created yet." message on my page.  How do I get around this? Bonus continent troops in Risk So I have taken over all of Australia and I get 2 extra troops.    My friend then attacks Indonesia from Southeast Asia. When it's my turn I retake control of Indonesia.  Now, do I get 2 more bonus troops since I retook control over the continent? Securely erase hard drive using the Disk Utility I am planning on selling my laptop. So I formatted my disk using the Disk Utility and chose to overwrite the disk with zeroes.  Two questions:  Is this the same as overwriting the disk using dd?  sudo dd if=/dev/zero of=/dev/sda   And is this method secure enough so that buyers can't easily recover the previous data? Or should I take additional measures (like encrypting the disk, destroying the headers, etc.)? I am using Apache Felix and its Declarative Services (SCR) to wire the service dependencies between bundles.  For example, if I need access to a java.util.Dictionary I can say the following to have SCR provide one:  /** * @scr.reference name=properties interface=java.util.Dictionary */  protected void bindProperties(Dictionary d) { }  protected void unbindProperties(Dictionary d) { }   Now, I have more than one Dictionary service available, and I want to filter them using the "name" service property (I only want "name=myDictionary"). I can do that with code (using a ServiceTracker), but I'd rather specify the filter in the @scr annotation instead. How do I depower overpowered magic items without breaking immersion? I've got two arrays of the same size.  I'd like to merge the two so the values of one are the key indexes of the new array, and the values of the new array are the values of the other.  Right now I'm just looping through the arrays and creating the new array manually, but I have a feeling there is a much more elegant way to go about this.  I don't see any array functions for this purpose, but maybe I missed something?  Is there a simple way to this along these lines?  $mapped_array = mapkeys($array_with_keys, $array_with_values); Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is no (due to type erasure), but I'd be interested if anyone can see something I'm missing:  class SomeContainer&lt;E&gt; {     E createContents()     {         return what???     } }   EDIT: It turns out that  could be used to resolve my issue, but it requires a lot of reflection-based code, as some of the answers below have indicated.  I'll leave this open for a little while to see if anyone comes up with anything dramatically different than Ian Robertson's . How do I enable error reporting in PHP? Click Answer your own question Check community wiki A dialog box     Are you sure you want to make this post Community Wiki?   will appear, Click OK or Cancel; The same dialog will appear again.   Google Chrome 44.0.2403.107 / Windows8.1 / site rev 2015.7.25.3609 Roman numerals used for ordinals How do I get resolvconf to regenerate resolv.conf after I change /etc/network/interfaces? After updating /etc/network/interfaces with something very similar to below, how do I get /etc/resolv.conf to update?  I tried (as root) resolver -u, service networking restart but they didn't work. I also fixed the symlink for resolv.conf and tried resolver -u again. Finally in frustration I rebooted, which did fix the problem by rebuilding /etc/resolv.conf.  Ubuntu 12.04, 64bit server, all the latest patches installed.  Example /etc/network/interfaces:  iface eth0 inet static     address 192.168.3.3     netmask 255.255.255.0     gateway 192.168.3.1     dns-search example.com     dns-nameservers 192.168.3.45 192.168.8.10