I am looking to upgrade from Ubuntu 12.04 to a newer supported version.  I have an old PC that I dusted off and would like to start playing again with Ubuntu again. I loaded the latest Ubuntu 20 ISO on a DVD and PC boots from disk and I can install the version but it only provides choices for an install that would wipe my data. There is no choice to upgrade. I was wondering if there is prefered method I can use to upgrade and retain my photos, files and programs that I have installed. Any advice would help. I think the current kernel of 12.04 is probably so old that the install process is not allowing the new version to upgrade and to only install.
Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc
tikz: Ignore one path in bounding box calculation Special event cards and timing Why does the variance of the Random walk increase? I have seen this construct in scripts a lot and used it myself, but it bothers me that I can't seem to find it in the documentation.  Example:  [ -f file1 ] &amp;&amp; [ -f file2 ] &amp;&amp; echo "Both files exist." || echo "One or the other file doesn't exist."   This could also be done with backslashes before the newlines, as mentioned in man bash:  If a \&lt;newline&gt; pair appears,  and  the  backslash  is  not itself  quoted,  the \&lt;newline&gt; is treated as a line continuation (that is, it is removed from the input stream and effectively ignored).   Example:  [ -f file1 ] &amp;&amp; \ [ -f file2 ] &amp;&amp; \ echo "Both files exist." || \ echo "One or the other file doesn't exist."   ...but this doesn't seem to be necessary.  The first version above works even without the backslashes.  Where can I find this in man bash?  (Also, is this bash specific or POSIX compliant?) Stop generating "possible duplicate" comments When a question has pending close votes, the system now adds a banner indicating that the question might be a duplicate:    But the first user to vote still generates a possible duplicate comment:    Those comments were always a hack, just like editing the link into the top of the post. The banner eliminated the need for the latter; can we stop generating those comments too? Two Clash of Clans accounts on one device I have been playing on two clash of clans accounts on one device for a long time but just recently i cannot switch from my lvl17 to my lvl75. The switch villages option is not popping up for me and I don't know why. Can anyone help me get my main account back? Infinite Product $\prod\limits_{k=1}^\infty\left({1-\frac{x^2}{k^2\pi^2}}\right)$ Draw Lewis structures like a book I want to draw a Lewis structure as in the picture. I tried to do with chemfig but does not perform the separation of the points and a minus in the superscript. How to derive the least square estimator for multiple linear regression? Is a photon "fixed in spacetime"? Finding minimum-area-rectangle for given points? As you see in the figure,  the question is:    How to find the minimum-area-rectangle (MAR) fitted on the given points?    and a supporting question is:    Is there any analytical solution for the problem?    (A development of the question will be to fit a box (3D) to a cluster of points in a 3D point cloud.)  As a first stage I propose to find the convex-hull for the points which reforms the problem (by removing those points are not involved in the solution) to: fitting a MAR to a polygon.  The required method will provide X (center of rectangle), D (two dimensions) and A (angle).      My proposal for solution:     Find the centroid of the polygon (see )   [S] Fit a simple fitted rectangle i.e., parallel to the axes X and Y   you may use minmax function for X and Y of the given points (e.g., polygon's vertices)  Store the area of the fitted rectangle Rotate the polygon about the centroid by e.g., 1 degree Repeat from [S] until a full rotation done Report the angle of the minimum area as the result   It looks to me promising, however the following problems exist:   choose of a good resolution for the angle change could be challenging, the computation cost is high, the solution is not analytical but experimental. Let $x\in\mathbb{Q}$ with $x&gt;0$.  Prove that we can find $n\in\mathbb{N}^*$ and distinct $a_1,...,a_n \in \mathbb{N}^*$ such that $$x=\sum_{k=1}^n{\frac{1}{a_k}}$$ Will Determinism be ever possible? Why do I need multiple sites for the same property in Google Webmaster Tools? In researching the best practice for adding sites to the Search Console, I've often seen it suggested to add separate properties for different versions of the same website. Even in  it states:     "Similarly, if your site has http:// and https:// versions, you should   add each as a separate site."   I've seen the same suggested for www/non-www. So if a site is accessible at all the variations of http/s and www/non-www we should have four properties.  But what if the site is only accessible at one variant? i.e. https and www are forced via htaccess, so only  can ever be accessed - should we still add all the variants?   In essence, the problem is that I don't know why Google wants us to do this, so I can't work out if it'll be ok just to have one instance. How can I force a program to open in a specific desktop? I've created an environment where I use 3 different desktop configurations, but every time I reboot, I have to manually open each program in that target desktop to make it look like it did before.   So, I'd like to write a .bat file that can get all my programs running in their appropriate desktops. I'm wondering if something like this is possible:  "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -desktop:2 "C:\Program Files\My\Other\Software.exe" -desktop:3 ...etc.   Obviously, this example is not real, but I hope there's something similar. I don't care if it's hacky :) In a question related to introductory Galois theory, I was asked to given an example of a tower of fields $F \subset K \subset E$ such that $E$ is a splitting field for some polynomial $f(x) \in F[x]$, but that $K$ need not be a splitting field. The example that comes to mind for me is $\mathbb Q \subset \mathbb Q(\sqrt[3]{2}) \subset \mathbb Q(\omega_3, \sqrt[3]{2})$.  So I know that the minimal polynomial for $\mathbb Q(\omega_3, \sqrt[3]{2})$ over $\mathbb Q$ is $x^3-2$. This polynomial does not split in the intermediate field $\mathbb Q(\sqrt[3]{2})$.  I wanted to make sure that I'm justifying that this intermediate field is not a splitting field correctly. Now I may be confused about the books terminology. When we say something is not a splitting field, we always have to refer to a specific polynomial correct? I've read a term called a normal extension which I think refers to one in which every polynomial splits, but my book doesn't mention these.   If splitting field means with respect to the polynomial $x^3-2$, then I've already demonstrated that $\mathbb Q(\sqrt[3]{2})$ is not a splitting field. Also, it couldn't be a normal extension either because that polynomial doesn't split.  Does it sound like I'm understanding this correctly or are there some subtleties I might be missing? Orbit followed by a particle around Schwarzschild Black Hole How to check internet access on Android? InetAddress never times out Note: This question is specifically about installed, desktop software. There is  specifically about free cloud-based software and services.  What free programs should every GIS user have installed?  I'm not necessarily referring to ESRI extensions or open-source products, but others that increase your productivity and ability to handle GIS tasks.  For example:    for writing code snippets or editing XMLs.  or  for quick graphic editing. I use  daily and I think it's worth mentioning. It's not GIS-specific, but it's a great tool, especially if used independently and on multiple projects where purchasing time-management software isn't reasonable. While it's not focused on GIS development,  has proven to be very useful in terms of increasing productivity and monitoring system resources. I have created a GIS "sidebar" on my desktop that holds all of my development tools, as well as links to the online resources I used the most. It's nice to be able to use one location, rather than many (e.g. taskbar, bookmarks in browser, search engine). Rendering 2D sprites in a 3D world?