Trying to increase Swap file in Ubuntu 18.04 I have been following the solution given in the answer here:  However when I reboot the old swap is still in place.  $ free -h               total        used        free      shared  buff/cache   available     Mem:            31G        1.9G         27G        1.3G        2.3G         27G     Swap:          979M          0B        979M   I have a recommendation from VMWare Workstation to increase it to 4 GB.  $ cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # &lt;file system&gt; &lt;mount point&gt;   &lt;type&gt;  &lt;options&gt;       &lt;dump&gt;  &lt;pass&gt; /dev/mapper/ubuntu--vg-root /               ext4    errors=remount-ro 0       1 # /boot was on /dev/nvme0n1p2 during installation UUID=daf8150f-9039-42e9-972b-873a1cc274d0 /boot           ext4    defaults        0       2 # /boot/efi was on /dev/nvme0n1p1 during installation UUID=5181-A887  /boot/efi       vfat    umask=0077      0       1 /dev/mapper/ubuntu--vg-swap_1 none            swap    sw              0       0   How do I do this?
How can I modify the size of swap with LVM partitions? I'm trying to add/modify a swap partition on my LVM-formatted hard disk by using GParted from a LiveCD.  I only see one big partition taking up the whole disk.    Is there a hidden swap?    Does an LVM-formatted system even need a swap?  I'm using Ubuntu 12.10.
Preview Breaks with Invalid Tag Name [tag:+] In the formatted preview for Questions &amp; Answers, typing a tag link with an invalid tag name "crashes" the preview. As soon as you type the following the preview stops updating and an error can be observed in the Javascript console.   [tag:+]   Observed in Safari 7 and Chrome 31.   seems related to the business rule of not allowing certain characters in tags, but it sounds like a different bug. Laplace equation of composite function Suppose we have $f(x,y)$, which satisfies Laplaces equation: $\frac{\delta^2f}{\delta x^2}+\frac{\delta^2f}{\delta y^2}=0$  Does $f(\frac{x}{x^2+y^2},\frac{y}{x^2+y^2})$ also satisfy Laplace equation? Do electrons have shape? According to :     The electron has no known substructure. Hence, it is defined or assumed to be a point particle with a point charge and no spatial extent.   Does point particle mean the particle should not have a shape, surface area or volume?  But when I searched Google for the "electron shape" I got many results (like  and ) that says electrons are round in shape. How to identify "deictic center" for distinguishing "come" & "go"? Read this paragraph from this    My question is:  How to identify "deictic center" for distinguishing "come" &amp; "go"?  Let say I am at home &amp; I say "I am going to the zoo this evening", so the "deictic center" in this case is my home &amp; I move away my "deictic center".  But let say my friend Tom &amp; I currently at my home &amp; Tom said "Are you Coming to the zoo to see the lion?" &amp; I said "Ok, I am coming to the zoo this evening". So, the "deictic center" in this case is "the zoo" &amp; we move towards the "deictic center" (ie the zoo).  It feels like it is very arbitrary.  Note: See this , it said the selection of "deictic center" could be due to sympathy &amp; politeness. Why is vote time missing in the SE data dump and SEDE? Is there a particular reason why vote times are omitted in the data dump?  IMO this could be a very useful data-set. Is this one of the steps that was done to anonymize the data, or does it simply not exist? This would be a very good addition to future dumps to help build time-based relationships, which are currently very rigid and full of assumptions. Fatou's lemma and measurable sets I don't know how can I imply Fatou's lemma for any measurable sets $A_k$, that is, $$\lambda(\liminf A_k)\le\liminf\lambda(A_k).$$ How can I prove it? And is there any example in $\mathbb R$ of sequence of measurable sets $A_k$ such that $A_k\subset[0,1]$, $\lim\lambda(A_k)=1$, but $\liminf A_k=\varnothing$ ? Thanks for your help! Why am I getting authentication errors for packages from an Ubuntu repository? I'm experimenting with VPNs, so I wanted to install pptpd.  john@desktop:~$ sudo apt-get install pptpd [sudo] password for john:  &lt;snip&gt; The following extra packages will be installed:   bcrelay The following NEW packages will be installed:   bcrelay pptpd 0 upgraded, 2 newly installed, 0 to remove and 11 not upgraded. Need to get 90.5 kB of archives. After this operation, 442 kB of additional disk space will be used. Do you want to continue [Y/n]? y   And everything runs fine until I get down to here:  WARNING: The following packages cannot be authenticated!   bcrelay pptpd Install these packages without verification [y/N]? n E: Some packages could not be authenticated   No authentication?  I'm no security expert, but I'm fairly sure that's a bad thing.  So I .  john@desktop:~$ apt-cache policy pptpd pptpd:   Installed: (none)   Candidate: 1.3.4-3ubuntu1   Version table:      1.3.4-3ubuntu1 0         500 http://us.archive.ubuntu.com/ubuntu/ natty/main i386 Packages john@desktop:~$ apt-cache policy bcrelay bcrelay:   Installed: (none)   Candidate: 1.3.4-3ubuntu1   Version table:      1.3.4-3ubuntu1 0         500 http://us.archive.ubuntu.com/ubuntu/ natty/main i386 Packages   They're coming from Ubuntu.com and not being properly authenticated?  What's going on here? Using apostrophes correctly I've read a great article about the . But there are still some points that are unclear.  Why do we say...   school project but not school's project? car service but not car's service or even cars' service (plural form)? apostrophe usage but not apostrophe's usage or apostrophes' usage? Storing Images in DB - Yea or Nay? So I'm using an app that stores images heavily in the DB. What's your outlook on this? I'm more of a type to store the location in the filesystem, than store it directly in the DB.  What do you think are the pros/cons? How to remove version and thank you message from the admin footer Possible Duplicate:          Can anyone offer me advice on how to clean my camera's sensor?   Should I do this myself, or take the camera to a professional? Is it precarious, or easy with the right amount of care?   I have a Nikon D3000 that has a small dot off-center of the sensor. I believe it is dirt, and I would like to remove it. I'm tempted to use a cotton-bud, but I'm afraid that I might damage the sensor.  The dot appeared after a trip to a tropical area where the camera became wet. I took the lens off and a lot of moisture, and possibly some dirt, went into the camera. The lens became fogged-up.  When I returned from my trip I ran a hair dryer for (air only, without heat) 10 minutes through the battery compartment, believing this would circulate around and dry the camera. Consequently, I noticed many speckled dots around the sensor. I also believe there's a subtle but persistent haze when I look through the lens, but I could be wrong.  It's worth noting that the photos are fine, with no evidence of distortion or blurring. The camera is now dry and it's been months since this happened. But the dot on the sensor has been there since, like an itch I can't rub. Description of NSDictionary - why are some key names with quotes? How to use \def to redefine \end{split}? When I use \def to redefine \end{split}, there is an error.  \documentclass{article} \usepackage{amsmath}  \begin{document} \def\be{\begin{equation}} \def\ee{\end{equation}} \def\bs{\begin{split}} \def\es{\end{split}}  \be     \bs         a\\         b     \es \ee  \end{document}   The error is:      Runaway argument?      a\ b \es \ee       ! Paragraph ended before \split was complete.   However, if I don't use \def\es{\end{split}} and just modify the code to be  \documentclass{article} \usepackage{amsmath}  \begin{document} \def\be{\begin{equation}} \def\ee{\end{equation}} \def\bs{\begin{split}} \def\es{\end{split}}  \be     \bs         a\\         b     \end{split} \ee  \end{document}   it's OK. What's the problem? Thank you! How to send text to Notepad in C#/Win32? I'm trying to use SendMessage to Notepad, so that I can insert written text without making Notepad the active window.  I have done something like this in the past using SendText, but that required giving Notepad focus.  Now, first I'm retrieving the Windows handle:  Process[] processes = Process.GetProcessesByName("notepad"); Console.WriteLine(processes[0].MainWindowHandle.ToString());   I've confirmed it's the right handle for Notepad, the same shown within Windows Task Manager.  [DllImport("User32.dll", EntryPoint = "SendMessage")] public static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);   From here, I haven't been able to get SendMessage to work in all my experimentation.  Am I going in the wrong direction? Have red shifted photons lost energy and where did it go? I think the title says it. Did expansion of the universe steal the energy somehow? For the bar chart proposed, I would like to use different color for each single bar. How can I  do this?  \documentclass{article} \usepackage{pgfplots}  \begin{document}  \begin{tikzpicture}   \begin{axis}[     title=Title,         xbar,         xmajorgrids = true,         bar width=6mm,          width=12cm, height=5.5cm,          enlarge y limits=0.2,         xlabel={\#number},         symbolic y coords={A,B,C,D},         ytick=data,         nodes near coords, nodes near coords align={horizontal},   ]    \addplot coordinates {(1,A) (7,B) (5,C)(2,D)}; \end{axis} \end{tikzpicture}  \end{document} Conditional expection of gamma distribution on sum I have a process which consists of a number of events and what is known is the timings between the events. What I'm trying to determine is a distribution that allows me to determine a likelyhood that a new sample fits the distibution.  The issue is mainly that if you have lots of samples you can approximate the result using a standard gaussian and use the mean and standard deviation. But if you only have a handful of samples, the gaussian does not accurately represent the situation.  From what I've read it is common to model waiting times using the gamma distribution. Looking at how the process evolves it looks like it matches well. The unknown is the scale parameter, since the shape parameter I think should be the number of samples. What I've worked out so far is that given the timings $X_1 ... X_N$ you can say:  $$ \sum_{n=1}^N X_n \sim \Gamma(N,\theta) $$  ($N$ is known and fixed)  However, $\theta$ is unknown, but the maximum likelihood parameter is the average of the $X_i$ (according to wikipedia anyway).   My question is, can I use this to estimate a distribution for $X_i$, that is, since the $X_i$ are independent:  $$ N X_i | \sum_n X_n \sim \Gamma(N, \tfrac{1}{N}\sum_n X_n) $$  Something else I've wondered about. Suppose I do have information about $\theta$, say a distribution. How can I incorporate this into the model?  Edit: Clarified that N is fixed. I understand monsters only spawn in a 9 x 9 grid of chunks centered on the player, and I assume they stay around while they remain within that distance of you. But do they despawn as soon as you move away from them? Or do they remain? If so what (if anything) causes them to despawn? Are the rules any different for passive mobs?  Will running far away from an area and then coming right back clear it of monsters? I want to run an app in 'kiosk' mode for public unattended access via touch screen (no mouse or keyboard attached). I can already automate a network user logon and then the app launches (but only in last state - not necessarily full screen - which I want) I know with Workgroup Manager you can hide the dock, use simple Finder etc...but need something more powerful. Ideally it needs to monitor if the app crashes out and restart it / log limited user off and back on again.  Thanks  Phil It is not unusual for an Ubuntu (or other distro with apt package management) user to encounter the error: user@box ~ $ sudo apt install x [sudo] password for user:  Reading package lists... Done Building dependency tree        Reading state information... Done Package x is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'x' has no installation candidate  There have been several questions asked concerning this on various StackExchange sites,for example  on AskUbuntu, but these are generally about how to obtain the specific package despite the error. I have found no package that is not found simply (though not always easily) by determining if it is still distributed, and under which repository if so, and ensuring that repository is in apt.sources, or the worst comes to the worst downloading a .deb or source to compile. So my question is more general, and although I am guessing it has a rather simple and therefore non-exciting answer I cannot think how to find it by conventional search engine methods, so I turn to AskUbuntu: Is there a command or option I can use to determine what package / which packages reference the missing package?