Problem after upgrading to ubuntu 16.04 After upgrading to ubuntu 16.04 when I boot into ubuntu I can see a black screen asking for a username and password,when I entered all these details it shows welcome to ubuntu 16.04 and all those. But still I am not able to see the desktop. It still in the position of accept commands from me as in the terminal we used to get
My computer boots to a black screen, what options do I have to fix it? I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:
How do you force Chrome pages/tabs to crash using JavaScript? No updates since a long time Using Ubuntu, I have a habit of running: sudo apt update sudo apt upgrade   on every startup. But for a month, I guess, there have been no updates whatsoever. The message shows: All packages are up to date  Now I am starting to worry. Can there be a fault in my update manager? As far as I know, I've made no changes to the package manager settings. But no updates for almost a month seems kind of weird. Any feedback would be helpful. Thanks. Am I technically allowed to look up cards during a Magic tournament match? Am I allowed to look up a card during a game, if it's being played with serious Rules Enforcement? Either to read the full card from the Gatherer, or to try to find the exact card I'm vaguely thinking of.  Two possible scenarios:   An opponent has revealed a card previously, and I want to remember the exact details. (Something like the exact wording of a sorcery, mana cost, keywords on a creature, subtypes, etc. etc.) I have a "name a card and remove it from the opponent's deck" type card, and I want to, say, ask google for "Blue Gearhulk" to remember that it's that that one is called "Torrential Gearhulk".   Obviously, in casual or semi-casual games neither of these are a problem. Any reasonable opponent will just re-reveal the known card (assuming it IS still guaranteed to be known) or will accept "I name the Blue Gearhulk".  Also obviously, it seems unlikely that I (or anyone else) would get to the stage of playing at the REL without knowing the cards too thoroughly for this to be relevant.  But in principle... is it permitted? Or not? (and if not, is there a good reason, or just "we decided 'No'"?) Why doesn't the Sun appear green to our eyes? How to run grep on a single column? How are questions in the 'hot' tab on a site selected? I know questions on the "hot" tab of a site homepage are based on some sort of views/velocity criteria, but does anyone know the actual algorithm used?  Background: I was considering a feature-request about the "hot" tab, but I don't have enough information to speak about it intelligently. Speeding up a NOT IN subquery Good evening,  I'm currently up to try to improve the performance of some of my queries. As far as I know, statements like "IN" or "NOT IN" are even faster with a large amount of values if a subquery on an indexed field without conditions is used.  SELECT * FROM table1 WHERE field1 NOT IN (SELECT index_field FROM table2)   When it comes to use conditions at table2, the query becomes realy slow on a large amount of data.  SELECT * FROM table1 WHERE     field1 NOT IN (         SELECT             index_field         FROM table2         WHERE             user_id = '2'     )   I was thinking about using LEFT Join but when I need to to the filtering for the user_id, it also becomes slow.  How may I solve this problem? Currently, I've no clue about that.  The original query looked sth. like this  SELECT     i.* FROM stream_item si LEFT JOIN user__publisher_item ui     ON ui.user_id = 2     &amp;&amp; ui.item_id = si.item_id INNER JOIN item i     ON i.id = si.item_id WHERE      si.stream_id IN (5,7,8,9,19,24,29,42,43,44)     &amp;&amp; ui.id IS NULL || (         ui.`read` = 0 || ui.saved = 1     ) GROUP BY     si.item_id ORDER BY     si.`found` DESC LIMIT 0,10     id      select_type     table   type        possible_keys                                                                           key                 key_len     ref                 rows        Extra 1       SIMPLE          si      index       PRIMARY,stream_2_item,stream_id_found                                                   stream_2_item       4           \N                  663236      Using temporary; Using filesort 1       SIMPLE          ui      eq_ref      user_id_item_id,user_2_item,user_id_read_saved_hidden,user_id_saved,user_id_hidden      user_id_item_id     8           const,si.item_id    1           Using where 1       SIMPLE          i       eq_ref      PRIMARY                                                                                 PRIMARY             4           si.item_id          1      I have a table which represents the n:m relationship between stream and items. An unique item can be accessible via multiple streams. Based upon this i have a state-table for user dependent states of an item. Currently, the user-state-entry will only be generated, if the item was read or saved the first tim. Otherwise, there is no entry in the user_item table. In the beginning, this query was fine but now, it takes a lot of time. Even if I leave out the "INNER JOIN" it takes 7 seconds on the current tables with around 500k rows each.  The table-structure in the background is as follows:   stream stream_item //n:m relation between stream and items item //unique items stream_group //user-defined groups of multiple streams stream_group_streams //_n:m relation between stream_groups and streams_ user user_item //state-table that holds the user-dependent states of an item - if there is no state, no row exists for an item   I already asked this question at  but added my 2 Edits with further information to late so that I haven't got an answer anymore. Added activities, now names and labels and strings aren't registering Android Manifest file Finding Value of the Infinite Product $\prod \Bigl(1-\frac{1}{n^{2}}\Bigr)$ While trying some problems along with my friends we had difficulty in this question.   True or False: The value of the infinite product $$\prod\limits_{n=2}^{\infty} \biggl(1-\frac{1}{n^{2}}\biggr)$$ is $1$.   I couldn't do it and my friend justified it by saying that since the terms in the product have values less than $1$, so the value of the product can never be $1$. I don't know whether this justification is correct or not. But i referred to Tom Apostol's Mathematical Analysis book and found a theorem which states, that    The infinite product $\prod(1-a_{n})$ converges if the series $\sum a_{n}$ converges.   This assures that the above product converges. Could anyone help me in finding out where it converges to? And,   Does there exist a function $f$ in $\mathbb{N}$ ( like $n^{2}$, $n^{3}$) such that $\displaystyle \prod\limits_{n=1}^{\infty} \Bigl(1-\frac{1}{f(n)}\Bigr)$ has the value $1$? How to add repository from shell in Debian? Geomagnetic reversal? As teenager Tom Riddle is speaking to Harry Potter in the Chamber of Secrets, both he and Harry are refering to the real Voldemort in the third person. If Tom Riddle had succeeded in sucking all the life energy out of Ginny and had come back alive, wouldn't that have meant there were two Voldemorts in the world? The wraith one which had lived in Quirrell, and the newly constituted one?  This Tom Riddle clearly doesn't have the memories of the wraith version.   As a bonus: If they both existed, would they have competed against each other? What is a less offensive synonym for "hypocrite"? Is there a word that describe a person who doesn't "practice what they preach"? Basically, is there a synonym for "hypocrite" that carries less pejorative connotations?   For example, let's say a friend of mine says he is a Christian. Yet he engages in behaviors considered sins by the Bible, making him a hypocrite. And I would like to tell him I think he is a hypocrite.   What would be a good word to use here, so my criticism seems constructive rather than offensive?     I tried using a , but the synonyms that came up were even worse (ie: they are more offensive than "hypocrite"). Related (but different) question: , which asks what to call someone who knows they are in the group of people they criticize. I am trying to use the Directory.GetFiles() method to retrieve a list of files of multiple types, such as mp3's and jpg's.  I have tried both of the following with no luck:  Directory.GetFiles("C:\\path", "*.mp3|*.jpg", SearchOption.AllDirectories); Directory.GetFiles("C:\\path", "*.mp3;*.jpg", SearchOption.AllDirectories);   Is there a way to do this in one call? Attacks of the MAC construction $\mathcal{H}(m\mathbin\|k)$ for common hashes $\mathcal{H}$? Consider a common practically-collision-resistant hash function $\mathcal{H}$ (e.g. , , , ), perhaps based on the  as are the first three. We define a  $\mathcal{C}$ $$(k,m) \mapsto \mathcal{C}(k,m)=\mathcal{H}(m\mathbin\|k)$$ where $\mathbin\|$ denotes concatenation, $k$ is a secret key (constant, or at least of fixed size), and $m$ is a message (possibly of variable length). Assume that an adversary can (iteratively) submit queries with $m_j$ and obtain $C(k,m_j)$, and wants to obtain $k$ or otherwise compute $C(k,m)$ for some $m\ne m_j$.  That MAC $\mathcal{C}$ is not trivially bad. In particular, if $\mathcal{H}$ was indistinguishable from a random function in the , $\mathcal{C}$ would be secure. And even though $\mathcal{H}$ may have the , it does not turn into a devastating attack on $\mathcal{C}$.  The less impractical generic attack that I see is that if a collision was known for $\mathcal{H}$ with the colliding messages of moderate identical length, it could be deduced countless collisions for $\mathcal{C}$. Hence security is demonstrably not better than collision-resistance of $\mathcal{H}$ (for identical-length messages). We could assume that $k$ is half the size of the result of $\mathcal{H}$, and hope that the security is about  or  or , 280, 2128, 2256 hash rounds for SHA-1, RIPEMD-160, SHA-256, SHA-512.   What are the known attacks against $\mathcal{C}$ (better than the above), and their cost, for each of these common hashes?  Is there hope for an argument that an attack against $\mathcal{C}$ would turn into an attack of similar cost against $\mathcal{H}$, or hint of the contrary?  Update: this  is of interest, but I fail to find that it really answers the present question.  Update 2: I am aware that the construction considered is weaker than , and in particular is vulnerable to collision on $\mathcal H$; I stated that, and that it is thus pointless to have the key wider hopeless to target security against some attacks better than half the hash's size. I'm asking exactly what cryptanalytic attack better than finding a collision on $\mathcal H$ there are. There is room for such an attack only by exploiting a weakness in the structure or/and the round function of a concrete $\mathcal H$. How to clip an Openlayers OSM Background to a Vector Boundary? inputenc Error: Unicode char \u8: not set up for use with LaTeX This is with ref to my previous question .  \documentclass[11pt,table,a4paper]{article} \usepackage{lmodern} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage{CJKutf8} \usepackage[english,russian]{babel}  \newenvironment{SChinese}{%  \CJKfamily{gbsn}%  \CJKtilde  \CJKnospace}{}   \begin{document}  \selectlanguage{russian}   Это мой первый многоязычный докладе.   Инфантильный гипертрофический стеноз привратника - это серьёзное   \selectlanguage{english}   This is my first multilingual report.   \begin{CJK}{UTF8}{}   \begin{SChinese}     这是我的第一个多语种的报告。   \end{SChinese}   \end{CJK}    \end{document}   when I try to compile it, I get following error message.  LaTeX Warning: Unused global option(s):     [table].  (./data.aux (/usr/local/texlive/2011/texmf-dist/tex/latex/cyrillic/t2acmr.fd)) (/usr/local/texlive/2011/texmf-dist/tex/latex/lm/t1lmr.fd)  LaTeX Font Warning: Font shape `T2A/lmr/m/n' undefined (Font)          using `T2A/cmr/m/n' instead on input line 15.   ! Package inputenc Error: Unicode char \u8:  not set up for use with LaTeX.  See the inputenc package documentation for explanation. Type  H &lt;return&gt;  for immediate help.  ...                                      l.18 ...�ный гипертрофический стеноз привра...   How can I avoid such error message. Using VHDL code to design a JK Flip Flop I'm using quartus II to design a JK Flip Flop. However, my results show unknown output. Why is it?  Intended design circuit:    VHDL code:  library IEEE;  use IEEE.STD_LOGIC_1164.ALL;  entity JKFlipFlopGate is     port(         J,K,Clk : in std_logic;             --JK Flip-Flop gate input 1 &amp; 2         Q,Qbar : out std_logic              --JK Flip-Flop gate output     ); end JKFlipFlopGate;  architecture result of JKFlipFlopGate is         signal out1,out2,out3,out4 : std_logic;  begin     out1    &lt;= NOT(J AND Clk AND out4);                      out2    &lt;= NOT(K AND Clk AND out3);      out3    &lt;= out1 NAND out4;     out4    &lt;= out2 NAND out3;      Q       &lt;= out3;     Qbar    &lt;= out4;     end result; How to set up USB for Virtualbox? I'm using Ubuntu Maverick and Virtual Box 3+. I have Windows 7 Ultimate. The problem is that it doesn't detect USB drives in Windows 7, but USB peripherals (mouse + keybord) are working.  I followed , but I can't find the user group vboxusers. How can I continue? I would also like to upgrade to the latest version without any risk (without losing my virtual hard disk drive). When a ball is tossed straight up, does it experience momentary equilibrium at top of its path? This question has been asked many times all over the Internet and answers can be found on places such as yahoo and ask.com, but I'm not satisfied with those answers and I don't trust the validity of those places.  This seems like a more appropriate place to ask.  So, here's my train of thought and I would like to ask you if you think I'm right or wrong.  Even though most of the answers point to the fact that the ball does not achieve equilibrium because the force of gravity is constantly acting upon it, thus causing an acceleration, I still think there's a moment of equilibrium and here's why:  When the ball is traveling up, it's accelerating towards the ground and eventually reaches a point at which its speed reaches 0.  At this moment, isn't the reason the speed is 0 is due to the fact that net force is 0?  The force that made the ball travel in the upward direction was canceled out by the gravitational force.  So, the sum of forces at that brief moment is equal to 0, otherwise the ball would be moving.  I don't think gravity is the only force acting on the ball at that moment, since the throwing force was acting on it as well, until both canceled each other out for that brief moment.  Am I right or wrong?