How to fix Virtualbox error “Kernel driver not installed (rc=-1908)” on Ubuntu 14.04 and error vboxdrv failed somebody help i'm stack for that for 3 days, i try any install dkms and updates. it's not working then i always have error in terminal vboxdrv failed. thanks
VBox on 14.04, Kernel driver not installed (rc=-1908) On Installing Virtual box on Ubuntu 14.04, I got following message:     Kernel driver not installed (rc=-1908)      The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or there is a >permission problem with /dev/vboxdrv. Please reinstall the kernel module by executing      '/etc/init.d/vboxdrv setup'      as root. If it is available in your distribution, you should install the DKMS package >first. This package keeps track of Linux kernel changes and recompiles the vboxdrv >kernel module if necessary.   Then on following the   I entered these commands:  sudo apt-get install linux-headers-generic build-essential dkms sudo apt-get remove --purge virtualbox-dkms sudo apt-get install virtualbox-dkms   On Running the last command   sudo apt-get install virtualbox-dkms   I get an error:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable  distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies: virtualbox-dkms : Depends: virtualbox (&gt;= 4.3.10-dfsg-1) E: Unable to correct problems, you have held broken packages.   Just for reference, I checked the version of the Virtual Box, I got 4.3.16 r95972  It worked using the solution  sudo apt-get install build-essential module-assistant sudo m-a prepare   Second as mentioned in the error reinstall kernal module.  sudo /etc/init.d/vboxdrv setup   More Details are from
Delete all but the most recent n file for each group of files that share the same prefix in a directory My question is a bit different from some older questions simply asking for "deleting all but the most recent n files in a directory".  I have a directory that contains different 'groups' of files where each group of files share some arbitrary prefix and each group has at least one file. I do not know these prefixes in advance and I do not know how many groups there are.  EDIT: actually, I know something about the file names, that is they all follow the pattern prefix-some_digits-some_digits.tar.bz2. The only thing matters here is the prefix part, and we can assume that within each prefix there is no digit or dash.  I want to do the following in a bash script:   Go through the given directory, identify all existing 'groups', and for each group of files, delete all but the most recent n files of the group only. If there are less than n files for a group, do nothing for that group, i.e. do not delete any file for that group.   What is a robust and safe way of doing the above in bash? Could you please explain the commands step-by-step? How do I get the Minecraft GUI scale to go back to Auto? I have been playing Minecraft, and I went into the settings to see what could be changed. I was in display and I saw the GUI scale was set to "Auto", which was fairly large. I cycled through the scales until I got back to auto, but the GUI scale was stuck at normal size and wouldn't allow me to make it large again. I know this isn't such a big problem, but I really like big font and this is a constant bother to me. Finding an isomorphic subring of matrices Consider this example from the Rogue class traits:     Trained Skills: Stealth and Thievery. From the class skills list below, choose four more trained skills at 1st level.   &nbsp;&nbsp;&nbsp;&nbsp;Class Skills: Acrobatics (Dex), Athletics (Str), Bluff (Cha), Dungeoneering (Wis), Insight (Wis), Intimidate (Cha), Perception (Wis), Stealth (Dex), Streetwise (Cha), Thievery (Dex)   The Rogue is trained in Stealth and Thievery. However, they're also included in the Class Skills section, and it invites you to: 'choose four more trained skills' from that list. This seems to be similar for all the classes.  So can you train Stealth and Thievery as a choice as well have it initially trained or the equivalent for other classes? How do I tail a log file and keep tailing it when the latest one changes date? Matryoshka words I downloaded Linux CAPT driver V2.60 from Canon and installed both .deb packages, which were listed under the 64bit folder with Ubuntu Software-Center. My Canon printer still won't be recognized. Is there anything else I have to do? My printer is connected over USB.  Ubuntu would make a great replacment for my office, but unfortunately without printer support I will still rely on Windows. Complex number isomorphic to certain $2\times 2$ matrices? I have been trying to prove this, but I am having trouble understanding how to prove the following mapping I found is injective and surjective. Just as a side note, I am trying to show the complex ring is isomorphic to special $2\times2$ matrices in regard to matrix multiplication and addition. Showing these hold is simple enough.  $$\phi:a+bi \rightarrow \begin{pmatrix} a &amp; -b \\ b &amp; a \end{pmatrix}$$  This is what I have so far:  Injective: I am also confused over the fact that there are two operations, and in turn two neutral elements (1 and 0). Showing that the kernel is trivial is usually the way I go about proving whether a mapping is injective, but I just can't grasp this.  $$ \phi(z_1) = \phi(z_2) \implies \phi(z_1)\phi(z_2)^{-1} = I = \phi(z_1)\phi(z_2^{-1}) = \phi(z_2)\phi(z_2^{-1}).$$  So if we can just show that the kernel of $\phi$ is trivial, then it also shows that $z_1 = z_2$. The only complex number that maps to the identity matrix is one where $a = 1$ and $b = 0$, $a + bi = 1 + 0i = 1$.  Using a similar argument for addition we can just say that the only complex number $z$ such that $\phi(z) = 0\text{-matrix}$, is one where $a=0$ and $b=0$, $a+bi=0+0i=0$.   Surjective:  I forgot to add this before I posted, but I honestly don't really understand how to prove this because it just seems so obvious. All possible $2\times2$ matrices of that form have a complex representation because the complex number can always be identified by its real parts and since the elements of the $2\times2$ matrix are real then the mapping is obviously onto.  I have always had trouble understanding when I can say that I have "rigorously" proved something, so any help would be appreciated! Here's the scenario...    if (entry.Properties["something"].Value != null)   attribs.something = entry.Properties["something"].Value.ToString();   While effective and working correctly, this looks ugly to me.  If I don't check for a null before performing the ToString() then it throws an exception if the property was null.  Is there a better way to handle this scenario?  Much appreciated! According to  and my own understanding, the tilde expands to the home directory:  $ echo ~ /home/braiam   Now, whenever I want the shell expansion to work, i. e. using variable names such $FOO, and do not break due unexpected characters, such spaces, etc. one should use double quotes ":  $ FOO="some string with spaces" $ BAR="echo $FOO" $ echo $BAR echo some string with spaces   Why doesn't this expansion works with the tilde?  $ echo ~/some/path /home/braiam/some/path $ echo "~/some/path" ~/some/path The situation is somewhat like-  var someVar = some_other_function(); someObj.addEventListener("click", function(){     some_function(someVar); }, false);   The problem is that the value of someVar is not visible inside the listener function of the addEventListener, where it is probably being treated as a new variable. Viber notification is not in the right position 'POCO' definition Can someone define what exactly 'POCO' means? I am encountering the term more and more often, and I'm wondering if it is only about plain classes or it means something more? For $x,y\in I:=[0,1]$ define the relation on $I$ as $x-y\in \Bbb Q$. How big (using cardinal number) is the cardinality of the equivalence class $[1/\sqrt2]$?  I have tried to solve it by finding the equivalence class but I'm not sure about the method that I can solve the question. Please, can you help me to solve it. Algorithm over 2 pages I am writing a few rather large pseudocode functions using algorithm and algorithmic, i.e. my code looks something like:  \begin{algorithm}                      \caption{Coolest Algorithm ever}           \label{findme}                           \begin{algorithmic} [1]                   % enter the algorithmic environment \REQUIRE    Here are a few variables \\             variable 2 \\             variable 3  \ENSURE     this is the output \\             output 2  \STATE $some cool code here$ \STATE $some cool code here$ \STATE $some cool code here$ \STATE $some cool code here$ \end{algorithmic} \end{algorithm}   Unfortunately this code does not fit on one page and I am definitely not able to split it into some subfunctions or so (I already did that as far as possible).  So now I need to split up the algorithm into two pages, but I have no idea how.  The easiest way I can imagine is just to start a new algorithm on the new page, but this time letting the line counter start at line 35 or so instead of 1. But how can I do that?  Please not that there is already a similar question here on this site, but it deals with the package algorithmicx. I want to update ubuntu 11.04 throught apt-get. So I added the following lines in apt.conf  export http_proxy=http://username:password@proxyserver.net:port/ export ftp_proxy=http://username:password@proxyserver.netport/  export http_proxy=http://deepak:Deepak@123@12.1.1.1:3128   My question is: how do I insert special characters to a username or password?  For instance: my password for proxy is Deepak@123 and it is getting an error. In indirect speech we generally backshift the tense. For ex - Direct speech : "I am the most powerful person." Indirect speech : "He said that he was the most powerful person."  What if someone reports like -  He denied the charges claiming that he is/was the most powerful person. So here which is correct- is or was ?  Thanks in advance. How do I set read/write permissions my hard drives? How did they dispose old Joe's wife's body in the movie Looper (2012)? The reason given in the movie Looper for sending targets to the past is that it is difficult to dispose bodies.  From ,     Thirty years into the future in 2074, time travel is invented, but is   immediately outlawed. However, because by that point tracking   technology has rendered it nearly impossible to dispose of bodies   secretly, crime bosses turn to time travel to send their targets to   the past to be killed using "loopers": hired guns paid in silver to   kill whoever is sent to them.   When trying to capture old Joe, they kill his wife. So how did they dispose the body of his wife? Or is it difficult to dispose bodies only in US and not in China? And they came for old Joe only because the Rainmaker wanted to close the loops?  Could someone explain? What am I missing? Why do I see a double variable initialized to some value like 21.4 as 21.399999618530273?