In 2nd line here I see 'u001' then 'root', 1st is owner as I understand, but what is 2nd ?  drwx------ 13 u001 u001     4096 jun 21 03:29 .cache drwxr-xr-x 18 u001 root     4096 jun 21 03:30 .config drwxr-xr-x  2 u001 u001     4096 jun 21 02:54 Desktop   How could I change it to u001 ?
When I entered the -al attribute with the  command, I got the following:  anupam@JAZZ:~/blog$ ls -al total 76 drwxrwxr-x 13 anupam anupam 4096 Aug 28 21:45 . drwxr-xr-x 34 anupam anupam 4096 Aug 28 20:52 .. drwxrwxr-x  8 anupam anupam 4096 Aug 28 12:19 app drwxr-xr-x  2 anupam anupam 4096 Aug 28 12:19 bin drwxrwxr-x  5 anupam anupam 4096 Aug 28 12:19 config -rw-rw-r--  1 anupam anupam  154 Aug 28 12:19 config.ru drwxrwxr-x  3 anupam anupam 4096 Aug 28 12:37 db -rw-rw-r--  1 anupam anupam 1339 Aug 28 12:19 Gemfile -rw-rw-r--  1 anupam anupam 2871 Aug 28 12:19 Gemfile.lock drwxrwxr-x  7 anupam anupam 4096 Aug 28 21:45 .git -rw-rw-r--  1 anupam anupam  466 Aug 28 12:19 .gitignore drwxrwxr-x  4 anupam anupam 4096 Aug 28 12:19 lib drwxrwxr-x  2 anupam anupam 4096 Aug 28 12:29 log drwxrwxr-x  2 anupam anupam 4096 Aug 28 12:19 public -rw-rw-r--  1 anupam anupam  249 Aug 28 12:19 Rakefile -rw-rw-r--  1 anupam anupam  478 Aug 28 12:19 README.rdoc drwxrwxr-x  8 anupam anupam 4096 Aug 28 12:19 test drwxrwxr-x  6 anupam anupam 4096 Aug 28 12:33 tmp drwxrwxr-x  3 anupam anupam 4096 Aug 28 12:19 vendor   What does each column mean, and what does the total 76 signify here?
$M= \{ A \in Mat_{2 \times 2}{\mathbb{R}}| \det(A)=1 \}$ is homeomorphic to $S^{1} \times \mathbb{R}^{2}$ Why does $1+2+3+\cdots = -\frac{1}{12}$? $\displaystyle\sum_{n=1}^\infty \frac{1}{n^s}$ only converges to $\zeta(s)$ if $\text{Re}(s) &gt; 1$.  Why should analytically continuing to $\zeta(-1)$ give the right answer? Independence of disjoint events Redirecting stdout to a file you don't have write permission on When you attempt to modify a file without having write permissions on it, you get an error:  &gt; touch /tmp/foo &amp;&amp; sudo chown root /tmp/foo &gt; echo test &gt; /tmp/foo zsh: permission denied: /tmp/foo   Sudoing doesn't help, because it runs the command as root, but the shell handles redirecting stdout and opens the file as you anyway:  &gt; sudo echo test &gt; /tmp/foo zsh: permission denied: /tmp/foo   Is there an easy way to redirect stdout to a file you don't have permission to write to, besides opening a shell as root and manipulating the file that way?  &gt; sudo su # echo test &gt; /tmp/foo So the question is really hard I think. I tried using a simple way by calculating the probability of each combination that makes a sum divisible by six, but it would take forever. Does anyone have any ideas?  Suppose that we roll a six-sided die ten times. What is the probability that the total of all ten rolls is divisible by six? I have this function:  $$ f(x,y) = \frac {xy}{|x|+|y|} $$  And I want to evaluate it's limit when $$ (x,y) \to (0,0)$$ My guess is that it tends to zero. So, by definition, if:  $$ \forall \varepsilon \gt 0, \exists \delta \gt 0 \diagup \\ 0\lt||(x,y)||\lt \delta , \left|\frac{xy}{|x|+|y|}\right| \lt \varepsilon $$ Then $$ \lim_{(x,y)\to(0,0)}\frac {xy}{|x|+|y|} = 0 $$ So:  $$ \left|\frac{xy}{|x|+|y|}\right| = \frac{|xy|}{|x|+|y|} = \frac{|x||y|}{|x|+|y|} \le 1 |y| \lt \delta $$  So for any $$\delta \lt \varepsilon$$ the inequality is true. Hence, the limit exists and is equal to zero.  . Am I wrong or is Wolfram|Alpha wrong? What makes the number of neutrons the number of proton similar? Clear Android Market Search History? Any thoughts on how one might clear the Android Marketplace search history? For instance, if I recently searched for an android app in the marketplace, the marketplace search maintains a history list of which apps/keywords that I have recently looked for.    Thanks in advance! Is a general GRE score of X sufficient for entry to postgraduate degree Y? Question: I got general GRE scores of VR (verbal reasoning), QR (quantitative reasoning), and AW (analytical writing).  Is this a good score to apply for entry to postgraduate degree in field X?  How will this score look to the selection committee?    Note: This is an intentionally generic GRE question (with unspecified scores and field of study) which is intended as a template for a large number of questions asked on this forum regarding evaluating the scores on the general GRE test (e.g., , , , , , , , and ).  This question seeks answers that are applicable for an applicant for graduate-level programs in any field, based on any scores in the GRE general test.  The goal of this question is to provide a general reference to avoid the need for specific questions with particular scores/field of study. Contacting prospective advisors before graduate school applications - courtesy or annoyance? Last year, rather late during the MSc application cycle (after one round of funding was allocated - tardiness due to an abrupt change in my life situation), I emailed two professors from two schools that I most wanted to go to. I had perused their webpages and decided these professors had the specific research interests closest to my own.  My reason for contacting them before finishing my applications for their respective schools was that the applications included a large section for specific research questions that I wanted to investigate. So, I emailed these professors asking a bit about their work, because their webpages of course featured surface-level stuff.  One professor was very receptive and invited me to Skype with her so she could better explain herself and I could ask her questions. With her support, I was able to write an application that met her standards quite quickly.  The other professor told me - paraphrasing, of course - that he was too far into the process of choosing a new student for his research group to spend time helping me finish the application.  Let me be clear that the latter professor didn't say any harsh words and I have nothing bad to say about him. That said, the purpose of my question is to decide whether it's better for me as a prospective MSc student to email professors ahead of time like this. Was the latter's rejection likely due to my tardiness rather my emailing him? The more receptive professor made the point that she always wanted to have prospective MSc students write their own research proposals and get her approval before submitting the application. Is this common? If so, then I guess reaching out beforehand is a good thing to do, but earlier in the application cycle?  Thank you. Given the following class  public class Foo {     public int FooId { get; set; }     public string FooName { get; set; }      public override bool Equals(object obj)     {         Foo fooItem = obj as Foo;          if (fooItem == null)          {            return false;         }          return fooItem.FooId == this.FooId;     }      public override int GetHashCode()     {         // Which is preferred?          return base.GetHashCode();          //return this.FooId.GetHashCode();     } }   I have overridden the Equals method because Foo represent a row for the Foos table.  Which is the preferred method for overriding the GetHashCode?  Why is it important to override GetHashCode? In proof by induction, what does it mean when condition for inductive step is lesser than the propsition itself? My question is regarding the question posed at the end of the proof.  My answer is that the result does not hold for all $m \ge 7$ because when $m=7$, the result is $343 \le 128$, which is false.  Is there another way to answer this sort of question besides directly trying different values until you get a false result?  EDIT:  Another question I have regarding this solution is:  In the proof for the inductive step, we start by assuming $k \ge 10$. But along the way, the author mentions $k \ge 1$ and $k \ge 7$ to justify the inequality.  Why do we bother to do this instead of just sticking with $k \ge 10$? Zoom in/out on click in OpenLayers 3? How to install Ubuntu 18.04 alongside Windows 10 Proving “The sum of $n$ consecutive cubes is equal to the square of the sum of the first $n$ numbers.” This   states:      Example $\boldsymbol 3$. The sum of consecutive cubes. Prove this remarkable fact of arithmetic: $$1^3 +2^3 +3^3 +\ldots +n^3 =(1 +2 +3 +\ldots +n)^2.$$   “The sum of $n$ consecutive cubes is equal to the square of the sum of the first $n$ numbers.”      In other words, according to Example $1$: $$1^3 +2^3 +3^3 +\ldots +n^3 = \frac{n^2 (n+1)^2}{4}.$$   Should: $$1^3 +2^3 +3^3 +\ldots +n^3 = \frac{n^2 (n+1)^2}{4}$$ not be: $$1^3 +2^3 +3^3 +\ldots +n^3 = \frac{n^3 +(n + 1)^3}{2^3}$$ as everything in the left-hand side is cubed? 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. Adding a CMS to an existing Magento shop I am working on a project for 3 niche stores built on magento (using magento's multi-store function)  that each get roughly 50k unique visitors a day.  The sites don't currently have a blog or forum or any social networking aspects.    Would like to add a cms to each site that can be centrally run and would like it to take over the front end content from Magento.  Also would like it to maintain an online blog/publication of sorts with videos, articles, and the like with privileges to edit the content given to a dozen or so people with different privileges.  Want to add a forum to each site that is fairly robust and to possibly add some social networking aspects down the road, so extandability and available plugins/mods in each cms is important.  Other than shared login between the forums,blog/publication and store, would like to be able to integrate some content from the forums and blog/publication into the store as well.  After researching this a bit, I am inclined towards Drupal, but I haven't found any modules to integrate it with Magento.  Also, since the blog content will be done by about a dozen nontechnical people, I want something that is very easy to work with.  Lastly, since the site gets a good amount of traffic, speed and security are very important.  What CMS would you recommend integrating in this context?  Deciding between Drupal, Wordpress and ModX.  Also Plone as well.  Thanks. In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328):    I've seen designs that seem to "work" but operate outside the shaded envelope. Specifically, I've seen 3.3V (Arduino) designs that run the clock from an external 16MHz crystal. Clearly, this is out of spec. What are the practical negative consequences of running outside this envelope? Do photons lose energy due to gravitational redshift? If so, where does the lost energy go? In the gravitational redshift, the frequency of photons radiated from some source is reduced. As the energy of a photon is given by $\hbar\omega$, if the frequency is reduced where is the lost energy? Batch Convert Images from One Format to Another while maintaining directory structure, and removing originals I've looked at , and while it works there a few issues:   All converted images are placed in the directory from which the command is called. The original images are kept.   I need to convert around 70,000 .tif and .jpgs to .pngs.  It's really important the the files when converted are placed in their normal directories.    I can do a batch rm of .tff/.jpg's at the end if that's the best way to handle removing the old files.