Running $ sudo apt install  Results in this error. $ The package linux-hwe-5.4-headers-5.4.0-51 needs to be reinstalled, but I can't find an archive for it.  Any ideas how to resolve? Details for $cat /etc/apt/sources.list mike@MikeUbuntu3:~$ cat /etc/apt/sources.list # deb cdrom:[Ubuntu 18.04.3 LTS _Bionic Beaver_ - Release amd64 (20190805)]/ bionic main restricted  # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://us.archive.ubuntu.com/ubuntu/ focal main restricted # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic main restricted  ## Major bug fix updates produced after the final release of the ## distribution. deb http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ focal universe # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic universe deb http://us.archive.ubuntu.com/ubuntu/ focal-updates universe # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe  ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu  ## team, and may not be under a free licence. Please satisfy yourself as to  ## your rights to use the software. Also, please note that software in  ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://us.archive.ubuntu.com/ubuntu/ focal multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic multiverse deb http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse  ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse # deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse  ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. # deb http://archive.canonical.com/ubuntu bionic partner # deb-src http://archive.canonical.com/ubuntu bionic partner  deb http://security.ubuntu.com/ubuntu focal-security main restricted # deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted deb http://security.ubuntu.com/ubuntu focal-security universe # deb-src http://security.ubuntu.com/ubuntu bionic-security universe deb http://security.ubuntu.com/ubuntu focal-security multiverse # deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse deb http://archive.ubuntu.com/ubuntu bionic main universe restricted multiverse deb-src http://archive.ubuntu.com/ubuntu bionic main multiverse restricted universe #Added by software-properties
There are now errors when updating and I cannot install most software due to a corrupted  /etc/apt/sources.list   file. Is there a copy I can download to replace it?  The file would be for Ubuntu 12.04 (Final Beta) in the United States.
proving logical equivalence $(P \leftrightarrow Q) \equiv (P \wedge Q) \vee (\neg P \wedge \neg Q)$ Could a website force the browser to go into fullscreen mode? SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session I am an Indian passport holder travelling from China to India via Kuala Lumpur, on Air Asia tickets bought separately. The layover is 4 hours and 30 minutes.  Do I need a transit visa? I saw many saying that the latest version of Ubuntu 16.04 includes an opensource driver for ATI. I have an HP laptop with AMD 6770m + Intel HD 3000 hybrid graphics and wants to install Kubuntu on it. I created a bootable USB drive of Kubuntu 16.04 and booted from it just to check everything works perfectly (I don't want to install it separately and ruin bootloader as of now). But my laptop is getting too hot and the battery is not lasting for more than 30 mins. Also the brightness control is not working at all and it stays high always.   How can I get hybrid graphics on Kubuntu/Ubuntu working well? I am ready to turn off the ATI card since I am not going to play any games on Linux. I just need the Intel graphics + Cool Laptop + Good battery Life + Brightness control.  My BIOS setting for switchable graphics mode is FIXED. Do I need to change it to DYNAMIC?  UPDATE  I wasn't able to make things work in 16.04 so installed 14.04 LTS along with the AMD Catalyst driver. Now everything works perfectly fine. Below are the steps.   Clean install Ubuntu 14.04 LTS Install the fglrx catalyst drivers using “Additional Drivers” window. This will enable us to switch graphics Restart Ubuntu FAN Noise Fix - Refer this  and install i8kutils Brightness Control - Check this     is the official documentation for AMD/Intel hybrid graphics \@seccntformat only for section How do I change Wi-Fi Hotspot settings in Ubuntu with GNOME 3? How do I manage my hotspot connected devices or change the hotspot password? I can only see the Network Name, Security type and the Password but I can't seem to manage users or the network properties. Is there an efficient way to enumerate the unique subgroups of the symmetric group? Naïvely, for the symmetric group $S_n$ of order $\left | S_n \right | = n!$, there are $2^{n!}$ subsets of the group members that could potentially form a subgroup. In addition, many of these subgroups are going to be isomorphic to each other. I feel that the question has an easy answer in terms of the conjugacy classes, but I don't see how. If the answer generalizes to all finite groups, please elaborate! When moving large directories using mv, is there a way to view the progress (%)? The cp command on gentoo had a -g switch that showed the progress. Scenario (Ubuntu 16.04):  I compile and run a C program (with -g, I get the traditional Segmentation Fault (core dumped), and then (of course) there is no mythical "core" file to be found. Some digging says to modify /proc/sys/kernel/core_pattern with a command to the effect of: echo '|tee /home/me/my_core_folder/my_core_file' | sudo tee /proc/sys/kernel/core_pattern, and after doing this, I stop getting (core dumped) and start only getting the plain Segmentation Fault. I try things like gdb ./program_object_file.out core.pid which obviously doesn't exist (I was getting desperate), and of course try the plain gdb ./a.out followed by (gdb) core core.pid and variants of the commands where I spam the tab key desperately trying to get auto-completion to get me to where I need to be.  Question:  Is there a generalized way I can get to core dumps? I recognize that every machine that I touch seems to have a Michael Bay's Transformers-esque ability to reconfigure hardware and software such that no device I own can be expected to work normally out-of-the-box. Is there a simple algorithm/recipe I can follow to locate core dumps on my own machine as well as on other peoples' machines? I always find myself tutoring friends on stuff like this after no small amount of  work to get things working for myself and it would be nice to be able to run a command or something to get core files dumped to the directory which the executable was run from... is there any way to do this that should work on most (I would settle for "some") Linux/Unix machines? What are best practices for choosing and pairing fonts? I've always found font selection to be a little bit of a mystery. What factors should be considered when choosing a font? How does one successfully incorporate two fonts into a design?  I realize that some factors will include things like:   Legibility Scalability Appropriateness/Mood/Emotion   However, how does one objectively judge legibility or appropriateness? Are there objective principles that can be applied for font selection? If possible, please list resources or examples in your answers. Studies focused on the effectiveness of different fonts would also be extremely useful. St. Matthew's vs. St. Matthew Conservation of energy and Doppler effect? Picture/Video capture programs What software options are there for taking videos and or pictures within Ubuntu (Much like Apple's Photobooth)?  Please limit one software solution per answer and include key features/description of the software I'd like to get an advanced frame in Firefall. I've been told that I can use "Pilot Tokens" to unlock other frames without having to pay money.  How soon would I be able to unlock an advanced frame? Do I have to level a base frame all the way to level 40? More than once? How to capture a series of screenshots in Web Driver using Java Deriving of formula for finding the length of median In the below image    $AD$ is the median of $\triangle ABC$  We know that $m_A = \frac 1 2 \sqrt{2b^2 + 2c^2 - a^2} $    But can someone tell me how it's derived !! I am just unable to think of it !!   But I assume it muste be linked with the Appolonius Theorem !! How do I install Geforce GTX 660 in 13.10 Just bought a Geforce GTX 660 and replaced my Radeon HD 5870 (it finally died after 3 years). I'm having terrible problems getting the video card to work. As I only had command line options so far I've ran:  (purged fglrx*)  then  sudo add-apt-repository ppa:xorg-edgers/ppa sudo apt-get update sudo apt-get install nvidia-331  and then I started getting low graphics mode errors. did some searching on my tablet, and I tried several things but what finally worked better was:   sudo apt-get install bumblebee bumblebee-nvidia  However now that I'm logged into my computer finally, I have no access to terminal, no access to the top bar, and hitting Super Key does nothing, alt-f2 does nothing, and I only can post because I tried running WoW and it had an error and the error report opened a link.   All I can see on my desktop is my wallpaper and desktop icons. I can CTRL+ALT+F1, and navigate to the downloaded official nvidia driver, however that won't run because of x-server, and I can't run it from my desktop.   Can anyone help me? How do I pluralize Italian foods, like pasta noodles (spaghetti, macaroni)? Possible Duplicate:             Is it proper to say spaghettis for more than one spaghetti noodle?  What about macaronis as a plural for more than one macaroni noodle? How do you check if a JavaScript Object is a DOM Object? I'm trying to get:  document.createElement('div')  //=&gt; true {tagName: 'foobar something'}  //=&gt; false   In my own scripts, I used to just use this since I never needed tagName as a property:  if (!object.tagName) throw ...;   So for the second object, I came up with the following as a quick solution -- which mostly works. ;)  The problem is, it depends on browsers enforcing read-only properties, which not all do.  function isDOM(obj) {   var tag = obj.tagName;   try {     obj.tagName = '';  // Read-only for DOM, should throw exception     obj.tagName = tag; // Restore for normal objects     return false;   } catch (e) {     return true;   } }   Is there a good substitute?