What is mean by $_ , It may used like this  mkdir testdirectory;cd $_   It will redirect to the new directory      testdirectory   if i use like this , echo $_   It shows      testdirectory   Which means previously created directory.Actually what it means, I don't know really
What the reason the number of lines differs?  $ head -n 100000 ./access.log &gt; ./data/log.sample $ cat $_ | wc -l 1933424
Is it acceptable to use "is become" instead of "has become"? In the King James version of the Bible there is a verse like this:     The Lord is my strength, and my fortress, and my song. And He is become my salvation.   Is it still feasible to use "is become" instead of "has become" and what is the semantic difference? Financial proof to get a Schengen visa to France I am planning to apply for a Schengen visa to visit France. I have an attestation d'acceuil, but the visa requires I submit bank statement for the past 3 months. I can get this statement, but the problem is that my company has been paying my salary in cash for the past months, and I place the money into the account by myself.  Can I submit the following?   my accounting book (current account)  letter from the bank stating that I have money in it payslips for the past 3 months   Will that satisfy the financial requirements for the visa? to Global Variables inside functions How to delete contacts from the Windows 8 People app? I never really bothered to keep my Hotmail contact information up to date, so now that I connected it to Windows 8, suddenly I see all this outdated contact information or people I've long stopped talking to.    I don't see any buttons or options where I can click to delete someone.  So how do I clean up my Windows 8 People app and remove these contacts? When sending or forwarding emails using a personal or company domain using a  website or email client, how do I prevent the email from being incorrectly marked as spam? Should the network use thousands separators in numbers? Why can't two series-connected diodes act as a BJT? Another form of the question is: will joining two diodes with wires (pn-np) make a transistor-equivalent?  I read that they are not equivalent, but why? How can I automatically save screen shots by the press on the Prt Scr button? I want a screen shot to be saved automatically to a location I specify, as soon as I press the Prt Scr button on my keyboard, or the Alt+Prt Scr combo. I also want the date and time to be used as file name for each new screen shot. And I want the files to be saved as PNG images.  Is there a Windows program that would allow me to do just this? I don't want any other fancy features like editing and making notes, etc. just a plain simple program that will either automatically save the screen shots to a pre-set location or prompt me where I want to save it. I don't want to go through MS Paint to save the shots.  I guess what I'm after is a little bit of Linux behavior of Print Screen, but only for Windows. And I additionally want the files to be named by the date and time they were taken.  Update:  Meanwhile, I have found one called Greenshot. But I don't know how to get the file name pattern right.  This is the default pattern.  ${capturetime:d"yyyy-MM-dd HH_mm_ss"}-${title}   Can someone explain this? Why do they have the title capturetime and the quotation marks? It produces file names like this.  2013-01-26 15_24_28-Greenshot.png   And this is what it says about the file patterns in the program description.  ${YYYY} year, 4 digits ${MM} month, 2 digits ${DD} day, 2 digits ${hh} hour, 2 digits ${mm} minute, 2 digits ${ss} second, 2 digits ${NUM} incremental number, 6 digits ${title} Window title ${user} Windows user ${domain} Windows domain ${hostname} PC name   How do I get files that include year, month and day, separated by a dash, followed by hour, minute and second? I want to include a time for uniqueness of the file name. How to output HTML from JSP  block? I just started learning JSP technology, and came across a wall.  How do you output HTML from a method in &lt;%! ... %> JSP declaration block?  This doesn't work:  &lt;%!  void someOutput() {     out.println("Some Output"); } %&gt; ... &lt;% someOutput(); %&gt;   Server says there's no &ldquo;out&rdquo;.  U: I do know how to rewrite code with this method returning a string, but is there a way to do this inside &lt;%! void () {  } %> ? Though it may be non-optimal, it's still interesting. Story where radically different cultures live together and are defined by rulesets, some choose not to see each other, a house is used as a spaceship I think this novel came out in the 2000s.  There are many cultures that live close together but are very different, for example some pretend to be pre-industrial.  One of the main characters is a youth who grew up in a pretend pre-industrial society and is now exploring the rest of the solar system? ring-world?   Each culture experiences their own reality that is defined by a ruleset.  One of the rulesets becomes aggressively self-propagating and this is the problem that drives the plot.  At some point a tumbling house, just a normal house, is used to travel across space. \clipbox of a \scalebox not working properly in xelatex It seems to me that the terms "Teaching Assistant" and "Instructor" refer to a variety of positions. At some places, a teaching assistant is responsible for things like helping the actual lecturer by handing out papers, grading homework, etc., and instructors hold recitation sessions.  At other places, I saw the term "instructor" referring to the lecturer giving the course, while a teaching assistant is the person doing anything else (recitations, grading etc.).  Is there some widely accepted definition of the two positions?  For context: The question arose because I wasn't sure whether I'm using the correct terms in my CV -- I am a math graduate student, and I would like to make a distinction between jobs in which I only graded course assignments/final exams, and courses in which I held recitation classes* (and also participated in grading the final exams). Is it OK to use "Instructor" for the latter? What should the former be referred to as?  *In the course I'm currently teaching, the recitations are planned and written by the ones giving them (without the professors' supervision). Also, the people giving the recitations are not necessarily grad students (some already hold a PhD). I'm elaborating on that because from what I've seen, some of it could be relevant for the definition of the job. I'm new to regular expressions and would appreciate your help.  I'm trying to put together an expression that will split the example string using all spaces that are not surrounded by single or double quotes. My last attempt looks like this: (?!") and isn't quite working. It's splitting on the space before the quote.  Example input:   This is a string that "will be" highlighted when your 'regular expression' matches something.   Desired output:  This is a string that will be highlighted when your regular expression matches something.   Note that "will be" and 'regular expression' retain the space between the words. 408 Request Time-outs still continues I'm frequently getting 408 Request Time-out errors  when browsing through Stack Overflow and Meta. I used to get this four or five times a day before, but now it has become very frequent. I've read  in which Kyle Brandt ♦ says:     We send our web logs to SQL so we can query them. It turns out that we have a bug that prevents 408s from being logged to SQL. [...] I will do more extensive research when our 408s are part of queryable logs (should be a week or two [...]).   My internet connection is somewhat stable and I haven't experienced this issue on other sites before. I don't think it's a browser-specific issue as it is reproducible on latest versions of Google Chrome and Firefox (on Ubuntu 13.10). However, it is specific to Stack Overflow and Meta. I'm unable to reproduce this on other SE sites.  Am I the only one facing this issue? Could it be something wrong with the regional CDN or something like that? Could someone please take a look at this issue? ()  This appears when I try to close-vote questions, too: System.Drawing in Windows or ASP.NET services According to , it is not a particularly good idea to use classes within the System.Drawing namespace in a Windows Service or ASP.NET Service. Now I am developing a class library which might need to access this particular namespace (for measuring fonts) but it cannot be guaranteed that the host process is not a service.  Now there is a less optimal method I can fall back to if System.Drawing is unavailable, but if it is possible, I would rather use classes in System.Drawing. So what I would like to do is to determine at runtume if System.Drawing is safe or not, and if it is, use it, otherwise fall back to the suboptimal option.  My problem is: How could I possibly detect if System.Drawing is safe to use?  I think I should either   Detect if the current process is a Windows Service or ASP.NET service Detect if GDI is available Or maybe there is a way to ask System.Drawing.dll itself if it is safe to use   Unfortunately, I cannot come up with a way to implement any of these approaches. Does anyone have any idea? Why Did Dumbledore Let Harry Give the Remains of the Diary Horcrux to Dobby? J.K. Rowling confirms that Dumbledore knew the destroyed diary was the remains of a Horcrux;     JKR: "In essence divided," exactly, the "essence" being the soul. So Dumbledore knew all along that he must have- well, he suspected until Chamber of Secrets, and then at the point where he saw what was clearly the remains of a Horcrux, in other words, the diary, he thinks, "Okay. There you go. And not only has he definitely done it, but he's got to have more than one, because he's treated this one very casually."      Yet Dumbledore allows Harry to take this very dark magical artifact and return it to Lucius Malfoy (in order to free Dobby):     ‘Professor Dumbledore,’ he said hurriedly, ‘can I give that diary back to Mr Malfoy, please?’   ‘Certainly, Harry,’ said Dumbledore calmly. ‘But hurry. The feast, remember.’   Harry grabbed the diary and dashed out of the office.   Chamber of Secrets - page 248 - Bloomsbury - chapter 18, Dobby's Reward   Why did Dumbledore allow Harry to take the Horcrux before he had fully examined it, especially as Dumbledore knew it was a Horcrux? The Peverell ring had a lethal curse placed on it for anyone who tried to put the ring on. Why didn't Dumbledore check the diary for additional curses or Dark Magic before giving it to Harry? I would have thought Dumbledore would have wanted to keep whatever Horcrux relics he found.   Also, do we know what happened to the diary after Harry gave it back to Lucius Malfoy and Lucius threw it aside? Are there any instances in canon that place the diary back in Dumbledore's hands? How can I prove $\sqrt{2} ^{\sqrt{2}}$ is irrational? What are instructions on how to download videos from YouTube?    Notice: Terms of Service Violation  Please be aware that by following any of the answers below, you will be violating YouTube's . In particular, from Section 5.B.:     Content is provided to you AS IS. You may access Content for your information and personal use solely as intended through the provided functionality of the Service and as permitted under these Terms of Service. You shall not download any Content unless you see a “download” or similar link displayed by YouTube on the Service for that Content. You shall not copy, reproduce, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content for any other purposes without the prior written consent of YouTube or the respective licensors of the Content. YouTube and its licensors reserve all rights not expressly granted in and to the Service and the Content. What is the "correct" way of embedding text into math mode? Lets say I have something like:   \[ Let x = number of cats \]   (This is a contrived example, but pretend we are actually inside a long align environment block...) "Let" and "number of cats" need to be written like normal text, while x= needs to be math type text.  I've seen this:  \[ \mbox{Let } x = \mbox{ number of cats} \]   and this:  \[ \textrm{Let } x = \textrm{ number of cats} \]   They seem to produce equivalent output, but I'm not sure which is the "correct" one. Also, they are not ideal in that the extra space needs to be placed inside the text mode block, otherwise it is ignored as math mode and butts the text right up against the math.  Ideally there would be some command which allowed embedding text into an equation, which correctly inserted leading and trailing space around the block as required without adding space inside the text block.  How does one do that "correctly"? \sum caused \sqrt to not be slanted