Ubuntu 15.10 doesn't load unity
Unity doesn't load, no Launcher, no Dash appears
Why weren't everyone on Haruun Kal made a Jedi? Preview of CAD files in format .dwg I'm looking for a utility or a program for Ubuntu, and possibly even for Windows that is able to convert a CAD file format .DWG to PDF.   My need is to provide a preview of CAD files, and I thought that the easiest way is to convert them into PDF format, but I'm open to suggestions, even if there is only the possibility to convert them to JPG image file type or PNG would be fine.  What interests me is only to find some solution, no matter if it is commercial or free Regex for splitting a string using space when not surrounded by single or double quotes Is the converse of Cayley-Hamilton Theorem true? The question is motivated from the following problem:     Let $I\neq A\neq -I$, where $I$ is the identity matrix and $A$ is a real $2\times 2$ matrix. If $A=A^{-1}$, then the trace of $A$ is   $$ (A) 2 \quad(B)1 \quad(C)0 \quad (D)-1 \quad (E)-2$$   Since $A=A^{-1}$, $A^2=I$. If the converse of  is true, then $\lambda^2=1$ and thus $\lambda=\pm1$. And then $\rm{trace}(A)=1+(-1)=0$.   Here are my questions:   Is  $C$ the answer to the quoted problem?  Is the converse of Cayley-Hamilton Theorem, i.e.,"for the square real matrix $A$, if $p(A)=0$, then $p(\lambda)$ is the characteristic polynomial of the matrix $A$" true? If it is not, then what's the right method to solve the problem above? Traveling to Ireland with German National visa I am a student at the University of Stuttgart, Germany and I have a 1 year national visa for Germany and now as my holidays are ahead I was looking if my German visa is sufficient to travel to Ireland for some 10 days. I am a citizen of Republic of Armenia. How about a difficulty rating for questions? It might be useful to add a drop down field "Difficulty" for questions. With a very limited set of options, say:   Beginner Advanced Expert   This way, users could easily judge if they can answer a specific question (depending on their experience in the topic) and how much time it will probably take.  Beginners usually know they are new so they can easily select Beginner. Those with some experience just select Advanced and those working on a topic for years may chose Expert. I think it's not very difficult to judge halfway correctly.  And the difficulty rating does not have to be very precise anyway, it's more a rough estimate by the asking person.  As an addition, rep gained on this topic can be multiplied with a difficulty factor. This would solve the problem of lots of rep for often-viewed and easy to answer questions and few rep for less-viewed, difficult questions.  Update  Thank you so far for the answers. I clearly underestimated the fact that some users are going to always chose Expert difficulty.  Maybe readers voting on the difficulty would be a workaround. Of course, we cannot use the rep factor then, for the same reason.  This kind of voting would obviously introduce a whole new set of issues, since we could vote on both content and difficulty (I'm almost positive this kind of proposal existed before?). Proof that the set of irrational numbers is dense in reals During graduate studies online application submission period, is there any preference given for an applicant if he/she submits his application at the beginning of that period compared with someone who submits his/her application couple of hours before the deadline?  Or as long as the applications are complete there is absolutely no difference! Empty intersection and empty union If $A_\alpha$ are subsets of a set $S$ then   $\bigcup_{\alpha \in I}A_\alpha$ = "all $x \in S$ so that $x$ is in at least one $A_\alpha$"  $\bigcap_{\alpha \in I} A_\alpha$ = "all $x \in S$ so that $x$ is in all $A_\alpha$"  It is the convention that $\bigcup_{\alpha \in \emptyset}A_\alpha = \emptyset$ and $\bigcap_{\alpha \in \emptyset} A_\alpha = S$.   But if $x$ is in $\bigcap_{\alpha \in \emptyset} A_\alpha = S$ then $x$ is in all $A_\alpha$ with $\alpha \in \emptyset$ and therefore $x$ is certainly in at least one $A_\alpha$ with $\alpha  \in \emptyset$. But then $x \in \bigcup_{\alpha \in I}A_\alpha$.  Can someone help me and tell me what is wrong with this? Thank you. In Russian roulette, is it best to go first? Assume that we are playing a game of Russian roulette (6 chambers) and that there is no shuffling after the shot is fired.  I was wondering if you have an advantage in going first?  If so, how big of an advantage?  I was just debating this with friends, and I wouldn't know what probability to use to prove it. I'm thinking binomial distribution or something like that.  If $n=2$, then there's no advantage. Just $50/50$ if the person survives or dies.   If $n=3$, then maybe the other guy has an advantage. The person who goes second should have an advantage.   Or maybe I'm wrong. Any software for windows Writing custom (intelligent) microsoft windows firewall extension (C#/C++/C) Writing custom (intelligent) firewall for windows Installing nginx etc. on the same computer and use it as proxy with rules.   "You could not solve all Ddos problems with software" is not answer for this question.I want to reduce Ddos vulnarebility of my server.(It will stop low-level Ddos attacks)  Hosted solutions or cloud services are not related with this question.  Closing some of the ports and protocols via Microsot Windows Firewall is not related with this question.  Any idea?  EDIT After Questions  Low level: sample scenerio: 500 zombie clients and each of them sending 100 Custom Get/Post requests per second)   Web Application is on IIS. I want to stop attacks before they reach to IIS.  EDIT After Helpful Comment  How can the DDOS attack achieve its aim?   Exhausting bandwidth ( Not related with my question) Exhausting network hardware of server (NIC) ( Not related with my question) Exhausting server resources (RAM,CPU)  (Yep, I mean this)   If you stop attacks late, then you lost more resources! (Is this false?)   You can stop attacks on Web Application Level (in Asp.net MVc Code or in Handler) You can stop attacks on IIS (Dynamic Ip Restrictions)  You can stop attacks on lower levels (Firewall ..)   EXTRA INFO ABOUT THE LAST ATTACK (7 Hours ago)  When I connected server during the attack IIS Cpu Utilization was %92-%99. And when I try to connect homepage I got this error:  A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: SSL Provider, error: 0 - The wait operation timed out.) How do I move to a new tab in gedit using the keyboard? If I have multiple tabs open, how do I move from one to another? (Ubuntu 11.10; gedit 3.2.1) Should the personal/research statement be technical? Related:   I know I must describe my past and current research in my personal/research statement or statement of purpose. But do I use technical terms?  I was given the advice that since the people reading my statement are mathematicians (I am applying to US for applied mathematics), they should know what I am talking about.  Although I am applying to applied mathematics, it would also be nice to hear from other fields (biology, computer science, engineering etc) about this. Acne underneath skin Introduction  Okay, I've almost won my war. The battle, its almost won... However, I must still claim victory in my final battle. The battle against the little enemies, the ones that have fought with my blade of benzoyl peroxide every single day.  Problem  Through spot treatments I have been able to fell every single one of these spots, but only the ones on my face. I've been using a spot treatment with benzoyl peroxide in, which has worked really well for me. However, my issue comes here:     There are spots underneath my skin, I think. The areas where they come through are a bit red.   So, because there is still slightly red skin on my face, and I think this is causing my acne to constantly return. I need to stop this, and end my war once and for all.  What I've tried   Washing my face with a rag and sponge every day, three times a day Changing my pillow case every day Using a benzoyl peroxide spot treatment Minimizing how much I touch my face Not interfering with the spots with my fingers, not picking at them, not playing with them. Just letting spot creams eradicate them.   Conclusion  Seriously, this driving me up the wall. I spot cream in the evening, by the time tomorrow has ended and its time for a shower, they've all come back. Its like they're coming in waves, damn waves! I must put an end to this.  So, how can I prevent acne from coming back within the space of a single school day? How can I get rid of these once and for all? What types of measures could I try? I have no reason to visit my doctor, its only acne, but I have no idea what I can try now.  Is there even a point in me trying? I acknowledge that I am a teenager, but no others that I know seem to have acne/spots like I do. I updated to TeXLive 2017 and couldn't get newlfm.cls to work without errors.  Here is a minimal example:  \documentclass{newlfm} \begin{document} \begin{newlfm} \end{newlfm} \end{document}   LaTex is throwing undefined control sequence errors on \fancy@reset, \f@ncyolh, and \f@ncyorh.  What causes the errors?  What am I missing? Question of an isomorphism of $\epsilon_ 0$ and a subset of the rationals. I don't know if this question is appropriated for this site. Anyway, I'm searching for an isomorphism of order $f:K \longrightarrow \epsilon_o $, such that $(K, \leq)$ is a subset(proper or not) of $(\mathbb{Q}, \leq)$ and $\epsilon_o = \sup\{\omega, \omega^{\omega}, \omega^{\omega^{\omega}}, ... \}$. Actually,  I'm not finding neither an isomorphism between $K$ and $\omega^{\omega}$.  Thanks in advanced. I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:   1-234-567-8901 1-234-567-8901 x1234 1-234-567-8901 ext1234 1 (234) 567-8901 1.234.567.8901 1/234/567/8901 12345678901   I'll answer with my current attempt, but I'm hoping somebody has something better and/or more elegant. Find all entire functions such that $|f(z)|\leq |\sin(z)|$ for all $z\in\mathbb C$. Properly bootstrap drupal for standalone PHP file? This is what I have right now:  &lt;?php     define('DRUPAL_ROOT', '/var/www/clients/client1/web15/web');     include_once(DRUPAL_ROOT . '/includes/bootstrap.inc');     drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL); //  drupal_flush_all_caches();        $users = views_get_view_result('userlist', 'uid_list');     $i = 0;     foreach ($users as $user) {         $filename = 'sites/default/files/generated_pdfs/individual_pdf_report_' . $user-&gt;uid . '.pdf';         generate_employee_pdf($user-&gt;uid, $filename);         error_log('Generated ' . $filepath);         $i++;     }     // create object     $zip = new ZipArchive();     // open archive     if ($zip-&gt;open("sites/default/files/generated_zips/individual-reports.zip", ZIPARCHIVE::CREATE) !== TRUE) {         die ("Could not open archive");     }     // initialize an iterator     // pass it the directory to be processed     $iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator("sites/default/files/generated_pdfs/"));     // iterate over the directory     // add each file found to the archive     foreach ($iterator as $key=&gt;$value) {         $zip-&gt;addFile(realpath($key), $value-&gt;getFilename()) or die ("ERROR: Could not add file: $key");     }     // close and save archive     $zip-&gt;close(); ?&gt;   I'm getting a bunch of errors from the above when run standalone. Works fine in my module. Some of the errors are:  Warning: Invalid argument supplied for foreach() in drupal_depth_first_search() (line 56 of /var/www/clients/client1/web15/web/includes/graph.inc). Warning: Invalid argument supplied for foreach() in _module_build_dependencies() (line 229 of /var/www/clients/client1/web15/web/includes/module.inc). Warning: include_once(sites/all/modules/views_bulk_operations/actions/archive.action.inc): failed to open stream: No such file or directory in views_bulk_operations_load_action_includes() (line 56 of /var/www/clients/client1/web15/web/sites/all/modules/views_bulk_operations/views_bulk_operations.module). How to harden an SSH server? What measures can/should I take to make sure that security around my SSH server is absolutely impermeable?  This will be community wiki from the start, so lets see what people do to secure their servers.