SSH: Disable FTP(sftp) for certain users?
How to setup a restricted SFTP server on Ubuntu?
What is a good word to describe 'exceptional positive' research work? If $$Y=\sum_{i=1}^{N}X_i^2$$ where $X_i \sim \mathcal{N}(0,\sigma^2)$, i.e. all $X_i$ are i.i.d. normal random variables of zero mean with same variances, then $$Y \sim \Gamma\left(\frac{N}{2},2\sigma^2\right).$$  I know the chi-squared distribution is a special case of the gamma distribution, but could not derive the chi-squared distribution for random variable $Y$. Any help, please? Why does a lightsaber turn off when a Jedi dies or drops it? I rewatched the three newer movies and noticed that whenever a Jedi was killed, or let go of their lightsaber, it immediately turned off.  What was curious was that the lightsaber turns off right away, when a Jedi is killed, even before it leaves their hand (if it does fall out).  I could understand if the button needs to be held for it to stay on, but when a Jedi is shot and is still holding the lightsaber why would it turn off? SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session Run MySQLDump without Locking Tables I have scripts that expect specific drive letters for hard drives. Windows sometimes assigns the different drive letters (e.g. I expected my Maxtor drive to be E:, but it's now F:, therefore my scripts will fail), depending on the order of how the drives are plugged into my laptop.  In Windows 7, how do I assign a permanent drive letter to a drive? python list in sql query as parameter I have a python list, say l  l = [1,5,8]   I want to write a sql query to get the data for all the elements of the list, say  select name from students where id = |IN THE LIST l|   How do I accomplish this? How to disconnect selected mesh geometry? I don't know how to disconnect a face from the rest of the mesh in edit mode.  This isn't like pressing P to separate the selection into a completely different object. I just want to select a face and disconnect/rip it away from the rest of the mesh but keep it as a part of the original object.  One way to do it would be to duplicate the face with ShiftD and then delete the original face. But I suspect there is a "native" command for disconnecting selected faces and I would like to learn it. I am considering trying to setup a  system. It seems like this would be pretty straight forward if I had two graphics cards or if I didn't need hardware based OpenGL acceleration. Is it possible to setup a multi seat system with only a single dual-headed graphics card? Prove $\operatorname{rank}A^TA=\operatorname{rank}A$ for any $A\in M_{m \times n}$ I have created a VF page and used "render as pdf"  &lt;apex:commandButton value="Save to Opportunity" action="{!savePdf}"  /&gt;   Its working fine when i am using above line without rerender and oncomplete but when i am adding rerender or oncomplete it is not working.I am able to save the PDF in attachment folder but when i am trying to open its showing  "Unable to load document"  Even if i remove oncomplete and use Rerender then also its saving the attachment in Attachment object and when i view ,it is not loading and says "Unable to load document"      &lt;apex:commandButton value="Save to Opportunity" action="{!savePdf}"  oncomplete="myClose();"/&gt;   Javascript Code  function myClose(){      self.close();     window.opener.location.href="/{!$CurrentPage.parameters.Id}";  }   Class Code  public void savePdf() {      PageReference pdf = Page.GenerateQuotePDF;     pdf.getParameters().put('id',parentId);      Attachment attach = new Attachment();      Blob body;     body = pdf.getContent();     attach.Body = body;     attach.Name = 'Opportunity'+ '.pdf';       attach.IsPrivate = false;     attach.ParentId = parentId;     attach.ContentType = 'application/pdf';     insert attach;     }     Please help.. Too much space between links in post menu I recall being somewhat impressed by a novel I read a few years back – this book may be less than five years old – which featured a college-aged man.  He had a laptop which transformed into a troll goblin that served as his familiar.  In the story's universe, mages had switched to the Internet for most of their magic &amp; communication.  The main character was essentially a magical hacker, and spent much of the book fighting against his evil aunt (I think, I know it was a female relative) with the help of his cousin.  Older forms of magic were also featured, including using special paintings as magical portals, and spells being whistled by wizards.  It features a scene at a gas station where the laptop is disabled by a virus, and the main character whistles a spell to reanimate dinosaurs from the gasoline.  Is this ringing any bells? Engines that play Mangala? At  there is this "only in ubuntu" that says "Built in virus protection":  What is the Ubuntu built it protection? What is the program in charge of this and how does it work? Inkscape filters are not rendering correctly I'm running Inkscape 0.92.4 on Ubuntu Linux 19.10. My graphics driver is from NVidia. I'm given to believe that Inkscape's filters should work and render fairly similarly to how filters work in GIMP. My expectations are based on this image which shows various filter effects which ship with Inkscape:    However, when I apply filters to even very simple shapes, I get horrible pixelated garbage like this:      Can anyone help me understand what is wrong and how to correct it? Thanks! How do I install an individual package on a Linux system? I need to install a new TeX/LaTeX/ConTeXt package on my computer.  I'm running Ubuntu/Fedora/Slackware/Some-Version-Of Linux.  What are the possible ways to do this?    Note:&nbsp;&nbsp; We get a number of questions that essentially reduce to this one; it was felt a good idea to have one question-and-answer that can cover all the standard methods.  See  for the discussion.  The question-and-answer are CW so that more information can be easily added.  If you have information to add, please do so.  If you are unsure, leave a comment here or (preferably) in .  Comments on the question and answer will be periodically removed to ensure that the information is clear. Subsubsection: remove the newline (like paragraph) Using the article document class, how can one remove the newline at the end of a subsubsection title?  I am using \documentclass{article}; I do not currently use titlesec or any of the alternatives; I do use fancyhdr. When a 0-1-matrix with exactly two 1’s on each column and on each row is non-degenerated? [1] Let $A$ be an $n\times n$ matrix with entries in the set $\{0,1\}$ which has exactly two ones in each column and two ones in each row.  Give necessary and sufficient conditions for the rank of $A$ to be $n$. $L^p$ and $L^q$ space inclusion Let $(X, \mathcal B, m)$ be a measure space.  For $1 \leq p &lt; q \leq \infty$, under what condition is it true that $L^q(X, \mathcal B, m) \subset L^p(X, \mathcal B, m)$ and what is a counterexample in the case the condition is not satisfied?