How do I restore missing Launcher and Panel in Unity? I had this Ubuntu infinite login loop problem, and after searching the forum, I did these steps.  Ctrl + Alt + F6  ls -lah   I found -rw------- 1 root root 20 Dec .Xauthority  So I did chown username:username .Xauthority as mentioned by someone in the forums.  After this I tried to login from my user, and it worked, but now I'm facing a new problem, that is, the Launcher and Panel are missing.  Did I do anything wrong ?  Further I did  dconf reset -f /org/compiz/   But it gave an error   error: cannot autolaunch D-Bus without X11 $DISPLAY   How do I solve this problem?
Unity doesn't load, no Launcher, no Dash appears When I login, nothing happens.   I am presented with my desktop wallpaper.    No Dash, no Launcher, nothing.
I want to use a Java file SaveProp which is written in a package user. The class file has been placed in WEBINF/classes. Below are the two lines which cause the issue.  jsp:useBean id="user" class="user.SaveProp" scope="session"  jsp:setProperty name="user" property="*"   It throws:  The value for the useBean class attribute user.SaveProp is invalid   I'm using Tomcat 6.0. I have two tables, movies and categories, and I get an ordered list by categoryID first and then by Name.  The movie table has three columns ID, Name and CategoryID. The category table has two columns ID and Name.  I tried something like the following, but it didn't work.  var movies = _db.Movies.OrderBy( m =&gt; { m.CategoryID, m.Name }) I want to utilize beamer's \uncover command within ChemFig's reaction scheme environment, i.e.:  \schemestart     \chemname[-1ex]{\chemfig[][scale=1]{*5(-=(-=[:-60]O)-O-=)}}{Furfural}     \uncover&lt;2-&gt;{         \arrow(furfural--mf){-&gt;[*{0}HDO][]}         \chemname[-1ex]{\chemfig{*5(-=(-)-O-=)}}{2-Methylfuran}     } \schemestop   However, this results in numerous "undefined control sequence" errors.  Is there a way to use beamer's \uncover command within ChemFig?  Here is a full MWE:  \documentclass[10pt]{beamer} \usepackage{chemfig}  \begin{document}  \begin{frame} \frametitle{Stuff}  \schemestart     \chemname[0ex]{\chemfig[][scale=1]{*5(-=(-=[:-60]O)-O-=)}}{Furfural}     \uncover&lt;2-&gt;{         \arrow(furfural--mf){-&gt;[*{0}\textbf{HDO}][]}         \chemname[0ex]{\chemfig{*5(-=(-)-O-=)}}{2-Methylfuran}     } \schemestop  \end{frame}  \end{document} Proof of $a^n+b^n$ divisible by $a+b$ when $n$ is odd I read somewhere that     $(a^n - b^n)$         It is always divisible by $a-b$.   When $n$ is even it is also divisible by $a+b$.   When $n$ is odd it is not divisible by $a+b$.      and     $(a^n + b^n)$         It is never divisible by $a-b$.   When $n$ is odd it is divisible by $a+b$.   When $n$ is even it is not divisible by $a+b$.      I wonder what's the proof for this.  First postulate is clear. $(a-b)$ would or would not be a factor. Any light on others? Local file access with JavaScript Is there local file manipulation that's been done with JavaScript? I'm looking for a solution that can be accomplished with no install footprint like requiring .  Specifically, I'd like to read the contents from a file and write those contents to another file. At this point I'm not worried about gaining permissions and am just assuming I already have full permissions to these files. How to remove desktop environments? I installed few environments that I wanted to try out on Ubuntu 12.04, but none of them worked at all. It could be that I installed them all at the same time, meaning the OS didn't get a chance to work everything out, but either way, they didn't work. I would now like to remove them.   The one's that I installed are Xubuntu/Xfce, Lubuntu/LXDE, Kubuntu/KDE, Fluxbox, OpenBox, cinnamon, and MATE. I installed them. Everything seemed to have been working properly until I actually tried to use the shells and nothing loaded at all. Except for Fluxbox, I think that one worked. I want to know of any way to repair or perhaps just remove the packages entirely. I might have already removed them because I did the apt-get remove command on all of them, but they were still in the list on the login screen. What is a “protected” or "highly active" question? Questions can be protected (i.e. marked "highly active").   What does it mean for a question to be protected? Why are some questions protected? Who can protect and unprotect questions? Who can answer a protected question? How are protected questions displayed? When should I protect or unprotect a question? When does the Community user protect a question? How to prove: if $a,b \in \mathbb N$, then $a^{1/b}$ is an integer or an irrational number? It is well known that $\sqrt{2}$ is irrational, and by modifying the proof (replacing 'even' with 'divisible by $3$'), one can prove that $\sqrt{3}$ is irrational, as well.  On the other hand, clearly $\sqrt{n^2} = n$ for any positive integer $n$.  It seems that any positive integer has a square root that is either an integer or irrational number.        How do we prove that if $a \in  \mathbb N$, then $\sqrt a$ is an integer or an irrational number?      I also notice that I can modify the proof that $\sqrt{2}$ is irrational to prove that $\sqrt[3]{2}, \sqrt[4]{2}, \cdots$ are all irrational.  This suggests we can extend the previous result to other radicals.        Can we extend 1? That is, can we show that for any $a, b \in \mathbb{N}$, $a^{1/b}$ is either an integer or irrational? Is there any way to deserialize JSON into an object using JSON.deserialize if some of the property names in the JSON are reserved words in apex? I want to do something like this:  string jsonString = '{"currency" : "ABC"}'; public class JSONResult {     public string currency; } JSONResult res = (JSONResult) JSON.deserialize(jsonString, JSONResult.class); system.debug(res);   but of course I get an error that the identifier name is reserved. how to count dates entries monthwise from a resultset Where should collision detection logic be placed? I am developing a small 2D game engine. The characters have a paint method which currently does the following:   Calculate the new position of the character as per its speed, etc. Update the collision grid cell ** Draw the character at the new position   ** I have created a collision grid to reduce the number of intersection checks  Now the basic algorithm which I have thought for detecting collision is:   For Each Character     Check intersection with characters in surrounding 8 cells   I can simply place this code in the paint method. But here is the problem I anticipate.  Suppose two characters A and B lie in adjacent cells in the collision grid. Now as per the above algorithm in the iteration of character A it will detect that it has collided with B. In the iteration for character B it will detect that it has collided with A.  But I have an idea that when A detects that it has collided with B, it should inform B that it has collided with A. This would save lot of comparisons when there are more than 2 actors colliding. But I am not sure how to handle this. I think instead of every character checking for its collision, I should check for the collision inside the game loop.   Would this approach be correct? How have you handled this kind of problem? I thought of the collision grid thing myself. Are there any alternatives to collision grid logic? Is setting a higher nice level for a process an effective way to reduce its impact on system load/CPU time? I have an rsync cron job which is pushing the server load and triggering monitor alerts.  If I set the job to be run with a high nice level, would that effectively reduce the impact it has on system load values? How to find number of prime numbers between two integers I have two integers, x and y so that x &lt; y. How many prime numbers are there between x and y (exclusive). Is there a formula or algorithm to compute? Make browser window blink in task Bar How do I make a user's browser blink/flash/highlight in the task bar using JavaScript? For example, if I make an AJAX request every 10 seconds to see if the user has any new messages on the server, I want the user to know it right away, even if he is using another application at the time.  Edit: These users do want to be distracted when a new message arrives. TikZ: Intersection of two lines what is the easiest way to determine the intersection of two lines? I tried  \usetikzlibrary{intersections} \begin{tikzpicture}[every node/.style={black,above right}] \draw[name path=line 1] (0,0) -- (2,2); \draw[name path=line 2] (2,0) -- (0,2); \fill[red,name intersections={of=line 1 and line 2}]     (intersection-1) circle (2pt) node {1}     (intersection-2) circle (2pt) node {2} \end{tikzpicture} These two operators commute...but their eigenvectors aren't all the same. Why? As per the following example, and as in  In bash, where has the trailing newline char gone?, I want to know "why" it happens    x="$(echo -ne "a\nb\n")" ; echo -n "$x" | xxd -p  # Output is: 610a62  # The trailing newline from the 'echo' command #   has been "deleted" by Command Substitution   I assume there must be some very significant reason for a shell action, namely Command Substitution, to actually delete some data from the command output it is substituting... but I can't get my head around this one, as it seems to be the antithesis of what it is supposed to do.. ie. to pass the output of a command back into the script process... Holding back one character seems weird to me, but I suppose there is a sensible reason for it...  I'm keen to find out what that reason is... My 3 years old doesn't tell me when he needs to use the bathroom The question asks to compute:   $$\sum_{k=0}^{n-1}\dfrac{\alpha_k}{2-\alpha_k}$$   where $\alpha_0, \alpha_1, \ldots, \alpha_{n-1}$ are the $n$-th roots of unity.   I started off by simplifiyng and got it as:  $$=-n+2\left(\sum_{k=0}^{n-1} \dfrac{1}{2-\alpha_k}\right)$$  Now I was stuck. I can rationalise the denominator, but we know $\alpha_k$ has both real and complex components, so it can't be simplified by rationalising. What else can be done? How can I prevent system clipboard image data being pasted into a WPF RichTextBox