I have an Ubuntu 16.04 web server. It only hosts one site using Nginx. I want to keep things very simple, and store the index.html file and the whole website in /var/www/html.  I need to be able to FTP files into /var/www/html. I have installed vsftp. I've created a user with the useradd command, which I'll call exampleuser. I then used this command:  sudo usermod -d /var/www/html exampleuser   ... thinking that this would make the home directory of exampleuser to be the default directory when I log in by FTP.  However, when I attempt to log in by FTP, I get a "login error". I've checked and double checked my username and password and I'm certain they're correct, so I'm guessing it's a permissions issue (also because my experience is that most of the time in Linux when things don't work as hoped it's because of permissions). Though it's possible it could be a vsftpd configurations issue.   I think I've set the html directory in /var/www to have the right access:  /var/www$ ls -la total 12 drwxr-xr-x  3 root          root          4096 Nov 10 06:54 . drwxr-xr-x 14 root          root          4096 Nov 10 06:54 .. drwxr-xr-x  2 exampleuser exampleuser 4096 Nov 10 08:04 html   What do I need to do so that I can ftp to /var/www/html?
I have an ec2 instance on AWS which already installed a few Wordpress-es in it.  I want to set things up to let more people handle their own projects, with me also being able to go into the server using terminal if I still want to.  I have been following tutorials such as  and a few others.  I figured all of them just teach users how to sftp into their own home folder, also the steps keep saying addUser but some users already existed and removing them might cause some issue.  How can I give existing users the permission to use SFTP for Wordpress projects?  Let's say all my Wordpress projects are already under /var/www/ which has already been set up with www-data:www-data.  Really new with setting things like this.  Thanks in advance for any help.
Fisher's exact test on 2x4 table I am working on 4 different plants. I have the (RNA-Seq) data from sequencing. I look for two events E1 and E2, say, at certain positions in their genome. Let's say E2 is the common one and E1 is a special event. The positions I look for are identical across all 4 (in the genome). And let's say I see that the observation I have for 1 particular position is:      P1   P2  P3  P4 E1   0   20   0   17 E2 100   80 100  120    Here, P1 through P4 refers to plants and E1 and E2 refers to the events. E2 is more common. So, my objective is to actually check if E1 occurs more often in one or more plants than in the others. If they occur at the same proportion in all, of course it is not interesting to me.  I have 2 questions: (I have already asked  before but didn't get an answer)     Will a fisher test be right for this problem?    I hypothesize (Null) that the proportion of E1 is not different in occurrence between the 4 plants. Now, I set out to find if the proportion I have here is by any means significantly different. I use R, fisher.test() and I get p-value=2.5e-10. So, I reject my Null hypothesis for this case because I find strong evidence against it.  Sometimes, I have an observation like this,        P1   P2  P3  P4 E1   0   20   0  17 E2   0   80   0 120    then fisher.test() gives me a p-value of 0.147. So, I don't reject the Null   hypothesis. However, from a biological point of view, I would consider this significant. However fisher test answers the question I originally asked. I guess the proportion 0/0 for P1 and P3 are not useful (or not used).  So, my question is: Is it possible to modify the test such that it is sensitive even if E1 and E2 are 0 in 1 or more plants for a particular observation?     Having thought a bit to frame this post, I guess, in that case I have to ask a different question. Ubuntu 14.04 System Logging I've set up an Ubuntu 14.04 Server (from an Ubuntu 12.04 Server) but today I wanted to look in the auth.log but this file is not used. It seems that ´syslog´ was deleted.  How does Ubuntu 14.04 log? I need this for a server.  Thank you. Sum of $k {n \choose k}$ is $n2^{n-1}$ Is there a word for a question asked despite knowing the answer, but meant to elicit a response for the sake of the audience? In journalistic writing I often see writers, correspondents, and interviewers use questions in non-literal ways.  Of course there are rhetorical questions designed to make a point and not meant to literally elicit an answer.   Instead of that, I have in mind when an interviewer asks a correspondent, "why did she not go to the police?" when the interviewer already knows the story and knows the answer to the question, but wants the correspondent to articulate the answer for the audience's benefit.    Is there a commonly used term for this sort of a question?  A "leading" question generally implies an attempt to manipulate the respondent into giving certain responses, which is not exactly the same as what I'm describing. I have been building models with categorical data for a while now and when in this situation I basically default to using scikit-learn's LabelEncoder function to transform this data prior to building a model.  I understand the difference between OHE, LabelEncoder and DictVectorizor in terms of what they are doing to the data, but what is not clear to me is when you might choose to employ one technique over another.    Are there certain algorithms or situations in which one has advantages/disadvantages with respect to the others? Age from Date of Birth using JQuery I need to calculate if someone is over 18 from their date of birth using JQuery.  var curr = new Date(); curr.setFullYear(curr.getFullYear() - 18);  var dob = Date.parse($(this).text());  if((curr-dob)&lt;0) {     $(this).text("Under 18"); } else {     $(this).text(" Over 18"); }   There must be some easier functions to use to compare dates rather than using the setFullYear and getFullYear methods.  Note: My actual reason for wanting to find a new method is length of the code. I have to fit this code into a database field that is limited to 250 chars. Changing the database is not something that can happen quickly or easily. How does space affect the human body (no space suit, no space craft) How does "outer space" affect the human body? Some movies show it as the body exploding, imploding or even freezing solid.   I know space is essentially a vacuum with 0 pressure and the dispersion of energy makes it very cold. So are the predictions above accurate? Why is SQL Server losing a millisecond? I have a table structured like this:  CREATE TABLE [TESTTABLE] (     [ID] [int] IDENTITY(1,1) NOT NULL,     [DateField] [datetime] NULL,     [StringField] [varchar](50),     [IntField] [int] NULL,     [BitField] [bit] NULL )   I execute the following code:  BEGIN     INSERT INTO TESTTABLE (IntField, BitField, StringField, DateField)     VALUES ('1', 1, 'hello', {ts '2009-04-03 15:41:27.378'});       SELECT SCOPE_IDENTITY()   END   And then   select * from testtable with (NOLOCK)   and my result shows:  2009-04-03 15:41:27.*377*   for the DateField column.  Any ideas why I seem to be losing a millisecond?? Pass in an array of Deferreds to $.when() How to add a custom icon or symbol to a flag link? I'm working on a 'sample request' implementation for a commerce site using , , sessions and a little custom code.  I'd like to add an icon or a symbol to let people know that an item they are viewing has been flagged.  I'm not sure exactly how to approach this, I can imagine perhaps adding a conditional field that displays an image or check box that is then changed by  or ajax, or perhaps something more complicated in JavaScript?  It could really be as simple as adding a checkbox that is checked or unchecked as the flag link is clicked or maybe even changing the css/html on click to be identified as marked.   Anyway, grateful for any advice here. After a lot of messing around today I curiously observed that $a^2+b^2$ is only divisible by 3 when both $a$ and $b$ contain factors of 3.  I am trying to prove it without using modular arithmetic (because that would be way too easy), but finding it very difficult to do so.  Is there an easy way to prove this without using modular arithmetic?  I am also interested in a more general statement.  Namely, I want to find the values of $Z$ for which $Z \mid \left( a^2+b^2 \right)$ necessarily implies that $Z \mid \gcd \left( a,b\right)$.  We know that $Z$ cannot be 5, because $3^2+4^2=5^2$.  More generally, if $Z$ is the largest element of a pythagorean triple then the above implication does not hold. Gaps between arrows and labels Let's consider it case by case:  Case 1: Charged particle is at rest. It has an electric field around it. No problem. That is its property.  Case 2: Charged particle started moving (it's accelerating). We were told that it starts radiating EM radiation. Why? What happened to it? What made it do this?  Follow up question: Suppose a charged particle is placed in uniform electric field. It accelerates because of electric force it experiences. Then work done by the electric field should not be equal to change in its kinetic energy, right? It should be equal to change in K.E + energy it has radiated in the form of EM Waves. But then, why don't we take energy radiated into consideration when solving problems? (I'm tutoring grade 12 students. I never encountered a problem in which energy radiated is considered.) I was using this:    To try and create numbered examples in my document.  However, when I load it and put the example exe in that link in one of the separate Tex files (Introduction.tex) I include in main.tex, I get:  ./Chapters/Introduction.tex:14: TeX capacity exceeded, sorry [parameter stack s ize=10000]. \gb@ifnextchar #1#2#3-&gt;                        \let \reserved@d =#1\def \reserved@a {#2}\def \reserv... l.14 ... and political news \cite{washington_post}                                                   .  More importantly, when ...   Which is not even referring to the exe example I inserted but a couple of blocks of tex above it.  For info, here is my full code before my document begins:  \documentclass{report} % [fontsize=11pt,border=5pt] % standalone for the tree \usepackage{forest} % This overrides warnings like http://tex.stackexchange.com/questions/52576/difference-between-bookmark-levels-greater-than-one-what-does-this-mean \usepackage{bookmark} \usepackage{amsmath} \usepackage{subcaption} \usepackage{standalone} \usepackage[round]{natbib} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage[utf8]{inputenc} % This is for hyperlinks \usepackage{hyperref} \hypersetup{     colorlinks=true,     linkcolor=blue,     filecolor=magenta,           urlcolor=cyan, }  \urlstyle{same} % Not sure why I need to use this % \usepackage{graphicx} % \graphicspath{ {images/} } % \usepackage[pdftex]{graphicx} % fontsize=11pt,twoside]{scrartcl} % This is for numbered examples \usepackage{gb4e}   Would appreciate some help as I feel like my Latex is very messy here. How to dismiss the Windows 8.1 Upgrade banner? Can a child enter the UK on an accompanied visa and then leave the country alone? My daughter who is just under 18 has a child accompanied visa to the UK. I am traveling with her to the UK for a few days. We return from UK on the same day except that she returns to India and I am heading to San Francisco an hour later on the same day.   Is that okay or will we have an issue at immigration into the United Kingdom? My directory (in Linux) looks like com/com/{various,files} where com and com are folders of the same name and the second com holds the various files. I want the first com removed, but the second and files in the second kept. How to understand the memory usage and load average in linux server I am using a linux server which has 128GB of memory and 24 cores. I use top to see how much it is used. Its output is pasted at the end of the post. Here are two questions:  (1) I see that each of the running processes occupies a very small percentage of memory (%MEM no more than 0.2%, and most just 0.0%), but how the total memory is almost used as in the fourth line of output ("Mem:  130766620k total, 130161072k used,   605548k free,   919300k buffers")? The sum of used percentage of memory over all processes seems unlikely to achieve almost 100%, doesn't it?  (2) how to understand the load average on the first line ("load average: 14.04, 14.02, 14.00")?   Thanks and regards!  Edit:  Thanks!  I also really like to hear some rough numbers based on used percentage of memory to determine if a server is heavily loaded, since I once became the one who cramed the server without understanding the current load.  Is swap regarded as almost the same as memory? For example, when memory and swap are almost of same size, if the memory is almost running out but the swap is still largely free, may I just view it as if the used percentage of memory + swap is still not high and run other new processes?  How would you consider together CPU or memory (or memory + swap) usage? Do you become worried if either of them reaches too high or both?  Output of top：  $ top    top - 12:45:33 up 19 days, 23:11, 18 users,  load average: 14.04, 14.02, 14.00 Tasks: 484 total,  12 running, 472 sleeping,   0 stopped,   0 zombie Cpu(s): 36.7%us, 19.7%sy,  0.0%ni, 43.6%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st Mem:  130766620k total, 130161072k used,   605548k free,   919300k buffers Swap: 63111312k total,   500556k used, 62610756k free, 124437752k cached    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND  6529 sanchez   18  -2 1075m 219m  13m S  100  0.2  13760:23 MATLAB 13210 timothy   18  -2 48336  37m 1216 R  100  0.0   3:56.75 absurdity 13888 timothy   18  -2 48336  37m 1204 R  100  0.0   2:04.89 absurdity 14542 timothy   18  -2 48336  37m 1196 R  100  0.0   1:08.34 absurdity 14544 timothy   18  -2  2888 2076  400 R  100  0.0   1:06.14 gatherData  6183 sanchez   18  -2 1133m 195m  13m S  100  0.2  13676:04 MATLAB  6795 sanchez   18  -2 1079m 210m  13m S  100  0.2  13734:26 MATLAB 10178 timothy   18  -2 48336  37m 1204 R  100  0.0  11:33.93 absurdity  12438 timothy   18  -2 48336  37m 1216 R  100  0.0   5:38.17 absurdity 13661 timothy   18  -2 48336  37m 1216 R  100  0.0   2:44.13 absurdity 14098 timothy   18  -2 48336  37m 1204 R  100  0.0   1:58.31 absurdity 14335 timothy   18  -2 48336  37m 1196 R  100  0.0   1:08.93 absurdity 14765 timothy   18  -2 48336  37m 1196 R   99  0.0   0:32.57 absurdity 13445 timothy   18  -2 48336  37m 1216 R   99  0.0   3:01.37 absurdity 28990 root      20   0     0    0    0 S    2  0.0  65:50.21 pdflush 12141 tim       18  -2 19380 1660 1024 R    1  0.0   0:04.04 top  1240 root      15  -5     0    0    0 S    0  0.0  16:07.11 kjournald  9019 root      20   0  296m 4460 2616 S    0  0.0  82:19.51 kdm_greet     1 root      20   0  4028  728  592 S    0  0.0   0:03.11 init     2 root      15  -5     0    0    0 S    0  0.0   0:00.00 kthreadd     3 root      RT  -5     0    0    0 S    0  0.0   0:01.01 migration/0     4 root      15  -5     0    0    0 S    0  0.0   0:08.13 ksoftirqd/0     5 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/0     6 root      RT  -5     0    0    0 S    0  0.0  17:27.31 migration/1     7 root      15  -5     0    0    0 S    0  0.0   0:01.21 ksoftirqd/1     8 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/1     9 root      RT  -5     0    0    0 S    0  0.0  10:02.56 migration/2    10 root      15  -5     0    0    0 S    0  0.0   0:00.34 ksoftirqd/2    11 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/2    12 root      RT  -5     0    0    0 S    0  0.0   4:29.53 migration/3    13 root      15  -5     0    0    0 S    0  0.0   0:00.34 ksoftirqd/3 To show that $2$ | $x^{2n} - x^n$, $n \in \mathbb{Z^+}$ is the following adequate? 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).