I am currently using Ubuntu 15.04 and wish to upgrade to 16.04 LTS. I try:  sudo do-release-upgrade   But I get:  Checking for a new Ubuntu release No new release found   How do I move forward? Is my install simply reporting the wrong version number - how can I find out?  I mean, it looks like I am still on 15.04  lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 15.04 Release:    15.04 Codename:   vivid   What next steps can I take?  UPDATE  I followed the directions in  which caused a lot of 404 errors. I then realised that vivid was not in  and search replaced those urls back to  and, bingo, updates working as they should.  TL;DR: The sources list was clearly wrong. Fixed it.
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
Let $F$ be a field and let $a \neq 0$ be a zero of the polynomial $a_0 + a_1x + . . . +a_nx^n$ in $F[x]$.  I want to show that $\frac{1}{a}$ is a zero of the polynomial $a_n + a_{n-1}x + . . . + a_0x^n$  How can I do this? Is there a way to export each rendered layer as its own image? My scene uses multiple render layers.  I'd like to edit each rendered layer in Photoshop, and composite it in Photoshop.  Is there a way to export each layer as an individual image? What exactly do quotation marks around the table name do? I thought that the quotation mark (") was simply a type of grouping marker but I'm debugging some NHibernate code and notice that while  SELECT * FROM site WHERE site_id = 3;   Works fine  SELECT * FROM "site" WHERE site_id = 3;   fails with a table or view does not exist error.  What gives? This is what I saw when my plane was taxing to the runway at CDG:     Airplane mode was on and all other transmissions (except Location), including WiFi, mobile data, NFC and Bluetooth were off.  Location was not manually turned on by me, after I enabled Airplane Mode. It remained turned on.  What am I missing? Is GPS now so widely accepted on-board planes that Android changed its configuration to let this kind of signal/communication to pass through Airplane mode "block"?  I believe that  isn't a duplicate, because at that time (2016) Location was generally "included" in Airplane mode and was turned off by enabling it. What are the origins of the word "nice"? How to run sudo command with no password? How does the ubuntu user on the AWS images for Ubuntu Server 12.04 have passwordless sudo for all commands when there is no configuration for it in /etc/sudoers?  I'm using Ubuntu server 12.04 on Amazon. I want to add a new user that has the same behavior as the default Ubuntu user. Specifically I want passwordless sudo for this new user.   So I've added a new user and went to edit /etc/sudoers (using visudo of course). From reading that file it seemed like the default ubuntu user was getting it's passwordless sudo from being a member of the admin group. So I added my new user to that. Which didn't work. Then I tried adding the NOPASSWD directive to sudoers. Which also didn't work.   Anyway, now I'm just curious. How does the ubuntu user get passwordless privileges if they aren't defined in /etc/sudoers. What is the mechanism that allows this? In my project requirement to access table data from Mapd Database on GeoServer  Mapd(GPU Based database) Database documentation link:   But in GeoServer provided some extension to connect and access particular database  GeoServer Extension link:    How can I connect MapD databse with geoserver is there any plugin. Why is gradient the direction of steepest ascent? Compact vs Mirrorless - why pick one over another? What would be a reason for one to pick the compact (whatever it'd be P&amp;S or something more advanced) over mirrorless compact system camera  ?  Right now market is quite confusing — we have huge market of tiny-sensor compacts, we have mirrorless that use sensors in a size of these from P&amp;S cameras (Nikon 1 being notable example), we have compacts with sensors bigger than most popular mirrorless system (Canon G1X vs m4/3), we have lot of APS-C sensor mirrorless which are matched by some of the compacts (Fuji X100 being most notable example, but even Leica has its X2),  and to make it even more confusing — Sony released RX1 with full frame sensor, beating crap out of every mirrorless on a market.  So what are your arguments to pick compact over a mirrorless?  Why are they better, what's the reason behind logic of companies like Fujifilm which at the same time offers P&amp;S and X-mount mirrorless using same sensor size? Is there a way to disable certain Windows 7 keyboard shortcuts?  Specifically, in this case, I want to disable Alt+Space and WinKey+Space. Saleforce Too many future calls: 11 Are C++ Templates just Macros in disguise? Minecraft Forge 1.7.10 will not start My minecraft will not start on only that version, I have a Windows 7 computer with Java 8u20 installed, because the latest java 7 update will not work at all(plus imma dev for other stuff).   [22:26:39] [main/INFO] [LaunchWrapper]: Loading tweak class name   cpw.mods.fml.common.launcher.FMLTweaker  [22:26:39] [main/INFO] [LaunchWrapper]: Using primary tweak class name   cpw.mods.fml.common.launcher.FMLTweaker  [22:26:39] [main/INFO] [LaunchWrapper]: Calling tweak class   cpw.mods.fml.common.launcher.FMLTweaker  [22:26:40] [main/INFO] [FML]: Forge Mod Loader version 7.10.25.1208 for Minecraft   1.7.10 loading  [22:26:40] [main/INFO] [FML]: Java is Java HotSpot(TM) 64-Bit Server VM, version   1.8.0_20, running on Windows 7:amd64:6.1, installed at C:\Program   Files\Java\jre1.8.0_20  [22:26:40] [main/INFO] [LaunchWrapper]: Loading tweak class name   cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker  [22:26:40] [main/INFO] [LaunchWrapper]: Loading tweak class name   cpw.mods.fml.common.launcher.FMLDeobfTweaker  [22:26:40] [main/INFO] [LaunchWrapper]: Calling tweak class   cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker  [22:26:40] [main/ERROR] [LaunchWrapper]: Unable to launch  java.util.ConcurrentModificationException     at java.util.ArrayList$Itr.checkForComodification(Unknown Source) ~[?:1.8.0_20]     at java.util.ArrayList$Itr.remove(Unknown Source) ~[?:1.8.0_20]     at net.minecraft.launchwrapper.Launch.launch(Launch.java:117) [launchwrapper-  1.9.jar:?]     at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.9.jar:?]  Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and   will likely be removed in a future release Extended Euclidean Algorithm: backward vs. forward "need + verb-ing" vs "need + [to be] + verb-ed" 1 That sofa needs cleaning again. 2 That sofa needs to be cleaned again.  Which of the above senteces sounds more natural? And, is &quot;to be&quot; always needed in structures like 2, as, for example, in:  2/a You need your head examined. 2/b You need your head to be examined. How to show $ \sin x \geq \frac{2x}{\pi}, x \in [0, \frac{\pi}{2}]$? I have tried the following: $$ f(x) = \sin x-\frac{2x}{\pi} \\ f'(x)= \cos x-\frac{2}{\pi} \\ f''(x) = -\sin x \leq 0 $$ But this doesn't seem to be heading in the right direction as it would appear $f'(x)$ is decreasing and has a zero within the domain, so I'm not sure how this might be used to prove the inequality. Did I derive a new form of the gamma function? How to include PHP files that require an absolute path? I have a directory structure like the following;     script.php      inc/include1.php   inc/include2.php      objects/object1.php   objects/object2.php      soap/soap.php   Now, I use those objects in both script.php and /soap/soap.php, I could move them, but I want the directory structure like that for a specific reason. When executing script.php the include path is inc/include.php and when executing /soap/soap.php it's ../inc, absolute paths work, /mnt/webdev/[project name]/inc/include1.php... But it's an ugly solution if I ever want to move the directory to a different location.  So is there a way to use relative paths, or a way to programmatically generate the "/mnt/webdev/[project name]/"? Calculate $E(X^{2n})$ where $X$ is normal (0,1) I need help proving the following:  Let $X$ be normally distributed with parameters $\sigma=0$ and $\mu=1$. Let $n$ be a positive integer. Show that:  $$E(X^{2n})=\frac{(2n)!}{2^nn!}=:(2n-1)!!$$  I've tried the change of variables $Y=X^2$ and then calculating the integral, but got nowhere. Any hints?  Thanks in advance! $$\lim_{n \to\infty} \frac{n!}{n^n}$$  I have a question: is it valid to use Stirling's Formula to prove convergence of the sequence?