I did it... I guess everyone does it sometime, but this was my first. I executed sudo chown -R /usr/bin and before I realized my mistake, it was too late... Now I can't access sudo because I receive the following error: sudo: must be setuid root. I would really appreciate if I could avoid a complete reinstall of ubuntu because that would require far too much work :(  Here is the commands I've tried without success (in recovery mode):  chown root:root /usr/bin/sudo chmod 4755 /usr/bin/sudo   I've also tried chmod 0440 /etc/sudoers all without success. Any ideas about what I can try to fix it?  NOTE: Sorry for creating another one of these threads, but since I knew the exact command I executed to blow it all up, I thought that might make a difference :)
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?
During self-study, I ran across the question of how many ways six numbers can be chosen from the numbers 1 - 49 without replacement, stipulating that no two of the numbers be consecutive.  I can obtain a simple lower bound by saying that, in the worst-case scenario, when you choose a particular number, there are now three numbers that cannot be chosen next.  For example, if I first pick 17, then I can't choose 16, 17, or 18 for the remaining choices.  This gives me the lower bound  $$\frac{49*46*43*40*37*34}{6!} = 6,773,770 \frac{8}{9}$$  This is about 48% of ${}_{49}C_6 =  13,983,816$.  The real answer must be bigger (and an integer).  I haven't found a way to calculate it, though.  The original problem asked to show that the probability of having non-consecutive integers when you choose six is greater than 50%, so if the problem is complicated to count exactly, better approximations that show the answer is above 50% would also be appreciated.   Of course, I can use a computer to do the counting, but I'm interested in learning what methods I'm missing. JavaScript displaying a float to 2 decimal places More than one 'Open xxxxx here as Administrator' I want the option to open a Command window or Powershell window as Administrator from the drive and directory context menus in Windows.   I can have either by creating and populating the special 'runas' registry keys shown below, but is there a way I can have both listed on the context menu and have both run as Administrator?  [HKEY_CLASSES_ROOT\Drive\shell\runas] ... [HKEY_CLASSES_ROOT\Drive\shell\runas\command] ... [HKEY_CLASSES_ROOT\Directory\shell\runas] ... [HKEY_CLASSES_ROOT\Directory\shell\runas\command] ... [HKEY_CLASSES_ROOT\Directory\Background\shell\runas] ... [HKEY_CLASSES_ROOT\Directory\Background\shell\runas\command] ... Comprehensive list of tools that simplify the generation of LaTeX tables I have a user control that I load into a MainWindow at runtime. I cannot get a handle on the containing window from the UserControl.   I have tried this.Parent, but it's always null. Does anyone know how to get a handle to the containing window from a user control in WPF?  Here is how the control is loaded:  private void XMLLogViewer_MenuItem_Click(object sender, RoutedEventArgs e) {     MenuItem application = sender as MenuItem;     string parameter = application.CommandParameter as string;     string controlName = parameter;     if (uxPanel.Children.Count == 0)     {         System.Runtime.Remoting.ObjectHandle instance = Activator.CreateInstance(Assembly.GetExecutingAssembly().FullName, controlName);         UserControl control = instance.Unwrap() as UserControl;         this.LoadControl(control);     } }  private void LoadControl(UserControl control) {     if (uxPanel.Children.Count &gt; 0)     {         foreach (UIElement ctrl in uxPanel.Children)         {             if (ctrl.GetType() != control.GetType())             {                 this.SetControl(control);             }         }     }     else     {         this.SetControl(control);     } }  private void SetControl(UserControl control) {     control.Width = uxPanel.Width;     control.Height = uxPanel.Height;     uxPanel.Children.Add(control); } Novel about a teleportation device and a con artist alien Holomorphic function has at most countably zeros Let $f$ be holomorphic in a domain $U$, then $f$ has at most countably zeros.  How can I prove this statement? I have seen it in Sheng Gong  explicitly, but without any indications. Do I have to buy or need a 3D-enabled phone to use Google Cardboard? Google cardboard comes with 3D glasses. Does that mean that we will be able to watch 3D videos using a smartphone like the Moto-G (1st edition) which is not 3D enabled? I am using Ubuntu 12.10.  Please outline the different ways I can upgrade to 13.04. How do I get my Python program to sleep for 50 milliseconds? Prove $[0, 1]$ and $(0, 1]$ are equinumerous by use of bijection What my thought was that the bijection was a piecewise function:  $f(x) = 1/n+1$ if $x = 1/n$ for some $n \in \Bbb N$ and $x=1/n$ if $x \neq1/n$ for some $n \in \Bbb N$.  However, the textbook says this is incorrect. I don't actually see why. Was it a matter of brackets or the open variable $(0,1]$, which is what I tend to think. My question isn't how they receive the energy to jump, but why.  When someone views an element's emission spectrum, we see a line spectrum which proves that they don't exist outside of their orbitals (else we would see a continuous spectrum).  Electrons can be released in the form of beta decay, thus proving that they are capable of traveling outside of orbitals contrary to the statement my teacher said that they stay within orbitals. Then, to add to the confusion, the older model of rings floating around a nucleus has, from what I can tell, been outdated, which would support this model. My teacher's explanation was that the electrons made a quantum jump of some kind. How do electrons move between orbitals or do we know how they jump, excluding the reason that energy causes them to jump, and why are positrons formed sometimes instead of electrons in Beta decay?  When I'm asking "how do electrons jump" I would like to know how an electron can jump between each orbital such as how it moves and how it knows where to jump since it appears to be a jump where the electron doesn't slow into a orbital position. Specifically how they jump what is this Atomic electron transition, I understand that they jump and that they do this through absorbing and releasing energy but what is this Atomic electron transition other than what is already on the wikipedia article . Proof that $\suṃ̣_{k=1}^{n}k {n \choose k}$ for $n \in \mathbb N$ is equal to $n2^{n-1}$.  As a hint I got that $k {n \choose k} = n {n-1\choose k-1} $.  I tried solving this by induction but, in the inductive step I'm not arriving to the correct result. Is any quotient of a Euclidean domain by a prime ideal a Euclidean domain? Let $R$ be a Euclidean domain, i.e., a ring with a norm $N : R \rightarrow \mathbb N$ such that for any $a,b\in R$ with $b\not=0$, we may write $a = qb + r$ for some $q,r \in R$ with $N(r) &lt; N(b)$. Let $I$ be a prime ideal of $R$, so $R/I$ is a domain. Must $R/I$ in fact be a Euclidean domain?   I know that this is true if we replace "Euclidean domain" with "PID", and false if we replace it with "UFD", so there is no clear intuition to be gained from similar concepts. My first attempts at a proof was to borrow a construction from analysis and define a norm on $R/I$ by  $N(a + I) = \inf\{N(a+i) : i\in I\}$  but this didn't really get me anywhere.   So, this fact true? If so, how can I prove it? If not, whats a counterexample? What space does the spell Cloud of Daggers fill? I am trying to workout what template  (PHB, p. 222) would be on a grid. The spell states:     You fill the air with spinning daggers in a cube 5 feet on each side, centered on a point you choose within range.   So does that mean it would look like this:     Or like this:    From what I've read online, there seems to be some suggestion that it is a single square (tile) though this does stack with the spell description of "a cube 5 feet on each side".  Clearing this up for my group would be great, and I am sure our DM will be pleased as his monster were nicely diced by this spell. Thanks. Getting random row through SQLAlchemy When does a Square Matrix have an LU Decomposition? I'm trying to create a unit test to test the case for when the timezone changes on a machine because it has been incorrectly set and then corrected.  In the test I need to be able to create DateTime objects in a none local time zone to ensure that people running the test can do so successfully irrespective of where they are located.  From what I can see from the DateTime constructor I can set the TimeZone to be either the local timezone, the UTC timezone or not specified.  How do I create a DateTime with a specific timezone like PST? Violation of linearity assumption in Logistic Regression I built a logistic model with 7 continuous independent variable and 8 categorical (dummy) variables in R. I tested for the linearity assumption using the Box Tidwell test and all my variables show high significance.  I am wondering now, if the assumption is violated what it would mean for the coefficient estimates and if I still can run the model with caution.   I read about the approach of using regression splines but I am confused how I would determine those and interpret the model then. Every countably generated sigma algebra is generated by a random variable