I am trying to install VirtualBox from the Oracle Repository following this link: wget -q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add - wget -q https://www.virtualbox.org/download/oracle_vbox.asc -O- | sudo apt-key add - sudo add-apt-repository &quot;deb [arch=amd64] http://download.virtualbox.org/virtualbox/debian $(lsb_release -cs) contrib&quot; sudo apt update sudo apt install virtualbox-6.0 I want to install from the Oracle repository in order to fix the issue of VirtualBox Error: Kernel driver not installed (rc=-1908). But while trying to install Virtualbox 6 I have this error: ~$ sudo apt-get install virtualbox-6.1 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-6.1 : Depends: libc6 (&gt;= 2.29) but 2.27-3ubuntu1.2 is to be installed                   Depends: libqt5core5a (&gt;= 5.12.2) but 5.9.5+dfsg-0ubuntu2.5 is to be installed                   Depends: libqt5widgets5 (&gt;= 5.12.2) but 5.9.5+dfsg-0ubuntu2.5 is to be installed                   Depends: libvpx6 (&gt;= 1.6.0) but it is not installable E: Unable to correct problems, you have held broken packages.  I have found a similar question here:  but none of the answers work, and here are the next steps of the top answer of the similar topic: ~$ sudo rm -i /etc/apt/sources.list.d/virtualbox.list rm: cannot remove '/etc/apt/sources.list.d/virtualbox.list': No such file or directory ~$ sudo rm -i /etc/apt/sources.list.d/oracle-virtualbox.list rm: cannot remove '/etc/apt/sources.list.d/oracle-virtualbox.list': No such file or directory  3rd day of trying to install a Windows VM on my machine, please help :) UPDATE: The duplicate links didn't help.
After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Researching English/Christian families in India during first half of 19th century? Categorize my data into 3 groups Proving the number of iterations in the Euclidean algorithm Let m and n be natural numbers. Suppose $ min(m, n) \leq 2^k $ for some natural number k. Show that the Euclidean algorithm needs at most $ 2k $ iterations to find the GCD of m and n. Basically I have no clue how to start this proof, I think I should be looking at the remainders and somehow showing that $ a_{k+2} \leq \frac{a_{k}}{2} $ where $a_{k}$ represents the kth remainder. Other than that, I have no clue about where to begin. Is there some markup to post tags? I am wondering because I was editing my profile and I though it would be nice to put the languages I know and stuff like tags.  Is it possible to post a tag? If it's not, do you think it's possible to implement on the profile?  For example:  [c#]   Would generate    With tag formatting and link... If sup A $\lt$ sup B show that an element of $B$ is an upper bound of $A$ (a) If sup A &lt; sup B, show that there exists an element of $b \in B$ that is an upper bound for $A$.  I have argued that if sup A $\lt$ sup B, then choose an $\epsilon&gt;0$ such that sup A +$\epsilon \in B$. Since $a \le $ sup A for all $a \in A$, it follows $a \lt $ sup A + $\epsilon$ hence sup A + $\epsilon $ is an upper bound of A as well as an element of B.  (b) Give an example to show that this is not always the case if we only assume sup A $\le$ sup B.  I am having trouble extending my argument into an example which makes me think that it may not be correct.   Question: Is my argument for (a) correct? If not how would one show this fact? Can you give an example asked for in (b)? Thanks in advance.  I need to understand how I am assuming what I am supposed to prove in my approach. Can someone elaborate on that please? The other question doesn't really address this issue. Allow questions to be saved as drafts prior to posting $1,000 is pronounced as "one thousand dollars". Reading from left to right, it seems like it would make more sense to write the value as: 1,000$. This way the pronunciation of the value follows the way it's written. Every other numerical value I can think of places the unit after the value:   1 kg 1 L 1 m, etc...   I'm not sure if this question fits in with the rest of the questions on this site. But I'd like to know why currencies are so different from other quantities. Not to mention the need to separate groups of three digits with commas. I generated a key and copied it to my target:  ssh-keygen ssh-copy-id username@hostname   I left the the location of the key as default and did not set any passphrase.  For a small while after that, I was able to ssh username@hostname without being prompted for a password, and then it stopped working for some reason. Ubuntu not detecting second monitor I'm running Ubuntu 12.04 on a Lenovo x61s Thinkpad. As the screen's rather small and I want to do some video editing, I thought I'd plug in a monitor and use that. The monitor is Relisys JM777 (quite old).  When I plug it into my other computer, which is running Windows 7, it immediately mirrors the display; but when plugged into the Lenovo the monitor screen remains blank. The graphics card on the Lenovo is a "VGA compatible controller" according to SysInfo.   Anybody got any suggestions for getting this monitor to work? I'm quite new to Linux. Can I use mirroring to make a copy of my Database? I would very much like that the the appendix sections of the Table of Contents doesn't have a section numbers, dots, and page numbers. If I do the following  \documentclass{article} \usepackage{tocloft} \addtocontents{toc}{\cftpagenumbersoff{section}} \renewcommand{\cftdot}{} \begin{document} \tableofcontents \newpage \section{Appendix} \section*{Another Letter} \addcontentsline{toc}{section}{Another Letter} \end{document}   then the section "Another Letter" is left aligned, so it doesn't look like the  others.  Question  Is it possible to have "Another Letter" styled the same way as normal TOC entries, but just without section number, dots, and page number? How to configure idle period for auto locking screen I just installed a fresh Ubuntu 12.04 (Precise Pangolin).   I noticed that, there is no screensaver settings, which is fine. I like to control the period of time after which the blank screen is shown,which automatically locks the screen.  I do not want to enable screensaver. I only wish to be able to change the idle time period required to lock the screen automatically. It seems to me, it is by default around 10-15 minutes. Do I need Transit Visa to visit London for 4-5 hours during layover? Please be kind, I am an electronics nub.  This is in reference to getting an LED to emit photons.  From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons flow from the more negative side to the more positive side.  In an example experiment (involving a primary dry cell, a SPDT switch, a resistor and an LED) it states that the resistor MUST be connected to the anode of the LED.  In my mind, if the electrons flow from negative to positive, wouldn't the electron flow run through the LED before the resistor; thereby making the resistor pointless? Is it a scam if the person only wants to deposit into my account, not make a withdrawal? I've got two branches that are fully merged together. However, after the merge is done, I realise that one file has been messed up by the merge (someone else did an auto-format, gah), and it would just be easier to change to the new version in the other branch, and then reinsert my one line change after bringing it over into my branch. So what's the easiest way in Git to do this? Italics markup not working in comments If I enter the following mark-down source:  “*blah*”   into a question or answer, then it works, but in a comment it doesn’t. The asterisks remain literal and don’t turn into italics. Can I insert an image into an equation? I would like to use a small image in an equation, where a symbol like \alpha might otherwise be. Is there a nice way to do this? Can anyone recommend a simple API that will allow me to use read a CSV input file, do some simple transformations, and then write it.  A quick google has found  which looks promising.  I just wanted to check what others are using before I couple myself to this API. Ignored and watched tags seem broken For the longest time my ignored tags have been working but today they are not. They work on the home page but not the /questions page. However, if you choose the &quot;Gray out questions&quot; option then that fails. Arqade is the only site I've ever had a long-standing ignore list so I don't think I can blame cache. The same behavior seems to be exhibited on Stack Overflow but I added those ignore tags just moment ago so cache could be an issue. If it matters, I am using Chrome x64 v91.0.4472.77 on Windows 10 Via comments, this issue has been confirmed for Watched Tags as well.