In Ubuntu Bash, how do I compare a variable to a stdout value?
How do I compare two string variables in an 'if' statement in Bash?
Possible cardinality of power sets What cardinals can provably not occur as the cardinality of a power set? I know that $\mathbb N$ and natural numbers that are not powers of two are such cardinals. What else is out there? As a non-native speaker of English, it can often be hard to spot some of the errors that a native speaker would find. For a long time, I've been thinking about getting a native speaker to help me with proof-reading my texts (articles, theses, application, etc), but I don't quite know where to look. What are some good ways to get proofreading for your texts?  For example, are there any websites on the Internet where one can exchange proofreading services between different languages? (Say, if you help me proofread my text in language x, I'll help you with yours in language y.) "Whom" or "who" where the referent is both subject and object? I understand there has been so much on this topic but I am still confused. I get that if the person is the subject it is who and anything else is whom. However, I'm really struggling to work out this rule for the following sentence:     The scope of which his account of morality applies to is therefore restricted to those whom/who the ‘notion of justification to a being of that kind makes sense.’   Should it be who or whom? I can't work out the subject and object. I have a loop going, but there is the possibility for exceptions to be raised inside the loop. This of course would stop my program all together. To prevent that I catch the exceptions and handle them. But then the rest of the iteration runs even though an exception occurred. Is there a keyword to use in my except: clause to just skip the rest of the current iteration? Find a recurrence relation for the number of $n$-digit binary sequences with no pair of consecutive $1$s.  I know my base case:$$a_1 = 2$$ for either $1$ or $0$. Normally to construct the recurrent relation I would say fill in $n-1$ spaces then add a $1$ or $0$, which is simply:$$a_n = 2\cdot a_{n-1}$$However, I don't believe this is right, because this doesn't take into account that there can't be any consecutive $1$s.  Even when I use the base case of $2$ digits:$$a_2 = 3$$for either $01$, $10$, or $00$, I still get the recurrence relation of:$$a_n = 3\cdot a_{n-2}$$which also does not account for $01$ and $10$ occurring consecutively.   So how would I express this? Cannot determine size of graphic I'm trying to include graphics in my Latex-file, which I compiled with latex+dvipdf on OS X. Latex however returns this error: "Cannot determine size of graphic"  My graphic is exported from PowerPoint, so I have tried both .pdf and .png. I get the same errors for both.  Sample code that doesn't work:  \begin{figure}[htb] \begin{center} \leavevmode \includegraphics[width=0.8\textwidth]{graph.png} \end{center} \end{figure}   If I have to manually set some measurements of the image, please tell me how I can find out those measurements. I need the image to take up about 80% of text width and be centered. Thanks. How does an accelerating charge radiate electromagnetic waves? How can I report bugs with or request features for the Stack Exchange mobile apps? I'm using the official Stack Exchange mobile app for iOS or Android, and  My app crashed! It doesn't look good on my new smartphone. It won't run after I updated my device. I noticed another bug. I have an idea for a new feature which is currently not in the app.  How do I report bugs with or request features for the iOS and Android apps? Also:  I've used the built-in functionality of the app to report a bug or submit a feature request. Did I do the right thing? The app prompted me to post on Meta after an error occurred. Should I post about it here? I'm wondering why the latest version is from 2017. I've heard rumors that the apps are no longer supported; is that true? I can't find the app on my device's app store anymore! Where did it go?     We get a lot of bug reports from users about the mobile apps, which are unsupported, and at the moment, there is no centralized Q&amp;A pair for those to be closed as duplicates of (the relevant answers are spread across multiple unrelated questions). This question is an FAQ proposal, to serve as a directly-related duplicate target for those questions. Delay jquery hover event? I would like to delay a hover event in jquery.  I am reading from a file when user hovers over a link or label.  I don't want this event to occur immediately in case the user is just moving the mouse across the screen.  Is there a way to delay the event from firing?  Thank you.  Example code:  $(function() {     $('#container a').hover(function() {         $('&lt;div id="fileinfo" /&gt;').load('ReadTextFileX.aspx',             {filename:'file.txt'},             function() {                 $(this).appendTo('#info');             }          );     },         function() { $('#info').remove(); }     }); });   UPDATE: (1/14/09) After adding the HoverIntent plugin the above code was changed to the following to implement it.  Very simple to implement.  $(function() {     hiConfig = {         sensitivity: 3, // number = sensitivity threshold (must be 1 or higher)         interval: 200, // number = milliseconds for onMouseOver polling interval         timeout: 200, // number = milliseconds delay before onMouseOut         over: function() {             $('&lt;div id="fileinfo" /&gt;').load('ReadTextFileX.aspx', {filename:'file.txt'},                 function() {                    $(this).appendTo('#info');                 }              );         }, // function = onMouseOver callback (REQUIRED)         out: function() { $('#info').remove();  } // function = onMouseOut callback (REQUIRED)     }     $('#container a').hoverIntent(hiConfig) } Do the beacon lighters really live on top of the mountains? Following this image I found online:    Do the beacon lighters really live on top of the mountains?  It seems really cold on top of some of these mountains and there are no villages or whatsoever. After using `networksetup -setdnsservers Wi-Fi "8.8.8.8" "8.8.4.4"` how do I clear them? I'm looking to script a temporary DNS server change to override the DHCP response I get from the network. I've figured out I can use networksetup but once we're done testing. Before I push to production, I figure I should know how to undo this.  How can I script to clear these changes and restore the settings the network provides now as if I never ran the following script?  networksetup -setdnsservers Wi-Fi "8.8.8.8" "8.8.4.4"   It's not feasible to save any the previous settings and I'm looking to remove the setting so that the actual new values can be retrieved from the network as opposed to saving what the settings were previously so I don't save an old value that is no longer correct.  Basically, I'm looking to ipconfig /renew on macOS. My lecturer has used some notation that I've never seen before: it is a (matrix) product symbol with a left-to-right arrow over the top. Does anybody know what this means?  Thanks in advance.  Edit: It looks like this: How to install hp scanjet 200 in Ubuntu 12.04? Unable to scan with hp scan-jet 200. When I type lsusb command in terminal it shows the scanner details.  I opened the simple scan which displays no scanners found, and x sane image scanners also displays the same error. Find html element which id starts with How to start a GUI application from cron? I'm participating in the  and wanted to refer to the on- and off-topic questions on the  proposal.  However, I couldn't find a link to it anywhere in the SE site.  If I'm not missing the obvious, could we have one? Learning Python programming with generic GIS goals in mind? In your opinion, what is the best book/site to learn Python with GIS goals in mind?  By "best", I mean:   not very long (book) easy to understand (book/site) good practical examples (book/site)   For answers specific to learning how to use the ArcPy site-package for Python to customize ArcGIS for Desktop there is a separate Q&amp;A: How do I go about porting Ubuntu Touch to different devices? I would like to port Ubuntu Touch to a device that is currently not supported. What are the requirements for doing this and where do I begin? Left-pad printf with spaces How can I pad a string with spaces on the left when using printf?  For example, I want to print "Hello" with 40 spaces preceding it.  Also, the string I want to print consists of multiple lines.  Do I need to print each line separately?  EDIT: Just to be clear, I want exactly 40 spaces printed before every line. Solving a Second Order Constant Matrix Differential Equation Given that $A$ is a constant coefficient matrix, how would one find a non-zero solution to the following equation: $$ x''+2Ax'+A^2x=0 $$ I am thinking this could incorporate systems of linear equations, but I am not sure how to use $x'=Ax$ or $x'=P(t)x +g(t)$ in this situation.   Any hints or suggestions are appreciated.