I want to transfer files from my Ubuntu (installed on VirtualBox Version 5.1.26) to Windows 7 host. I'm able to copy files from my host to guest using Shared Clipboard but I want to copy the other way round. I already installed Guest Additions as mentioned in   I've been through many other posts on the Internet but none worked for me. I can use WinScp or Putty or any other file transfer applications but that's not what I want, I don't want to use any alternative file sharing software for this.
I have an Ubuntu 12.04 machine on which I have installed VirtualBox with Ubuntu 12.04 as the guest OS.  How can I share files between the host and guest?   I have installed the guest additions also but still it’s not able to mount the sf_shared folders if even it’s mounted. This means I'm unable to retrieve the file from the host.
Inner product of two continuous maps is continuous Let f,g be continuous maps of S in $\mathbb{R}^n$, to $\mathbb{R}^m$. Show the inner product h(x) = $\langle f(x), g(x)\rangle$ is continuous.  My attempt: Since f,g are continuous, their product is a continuous mapping, so for $\epsilon \gt 0\: t.e\:  \delta \gt 0$ such that $\parallel x - a\parallel \lt \delta $ implies $\parallel \langle f(x),g(x)\rangle - \langle f(a)g(a)\rangle \parallel \le\parallel f(x)g(x) - f(a)g(a)\parallel \lt \epsilon$ by schwartz inequality. Removing Ubuntu from a dual-boot setup with Windows What is the pressure at the center of the Earth? (Or a neutron star) The  has microgravity and is thought to be solid and almost 6000 degrees hot. What is the pressure like there? The confusing thing, for the common man I suppose, is that there's no gravity there, but lots of matter around it which does gravitate towards the center. How does that add up? Is the center just a gas cloud or is it highly compressed?  And I could add the aside question about what it is like in the microgravity center of a  or a black hole, but I don't expect anyone to know about that. I wanted to tweet something on the lines of "Stack&nbsp;Overflow is awesome". When I do this kind of stuff, I usually use a username (for example: ) or a hashtag ()  I found , but it seems it is from someone unrelated with Stack&nbsp;Overflow.  Is there a Twitter account I can reference, or should I use a hash-tag? Should I just point to the site?  Thanks!  (Notice: I've seen lots of questions regarding Twitter and Stack&nbsp;Overflow, but those are mostly about integration/login with Twitter for the users accounts; I'm just asking for a single account for Stack&nbsp;Overflow; probably for announcements and PR, which is different) Logical volume is not mounted but is in use. Please close all applications using this device (eg iscsi) Scanning Java annotations at runtime What is the best way of searching the whole classpath for an annotated class?  I'm doing a library and I want to allow the users to annotate their classes, so when the Web application starts I need to scan the whole classpath for certain annotation.  Do you know a library or a Java facility to do this?  Edit: I'm thinking about something like the new functionality for Java EE 5 Web Services or EJB's. You annotate your class with @WebService or @EJB and the system finds these classes while loading so they are accessible remotely. Show that $\left|\frac{\alpha - \beta}{1-\bar{\alpha}\beta}\right| < 1$ when $|\alpha|,|\beta| < 1$ $$\lim _{x \rightarrow 0} \left(\frac{ \sin x}{x}\right)^{1/x}$$  I have spent an hour on the above limit and have no work to show. I tried using L'Hopital's Rule, but just kept going around in circles. Any help would be appreciated. Thank you. Could someone please explain the role of the transistor in this circuit? I have a feeling it has to do with the LC circuit but I'm not sure and don't understand completely. The following is an image of the circuit (the transistor is n-type. It is used in lots of sensors to detect and generate ultrasonic waves. Need help with a question regarding the Big Oh In class we are currently covering upper/lower bounds, big Oh and omega and the like. I am pretty good on the "typical" functions one would do, but at a complete loss at "general" statements. This ons function, for example:  $$\forall f\in\mathcal{F}: \lfloor \sqrt{\lfloor f(n)\rfloor }\rfloor \in O(\sqrt{f(n)}).$$  the domain F by the same is all natural numbers that return a real positive number when inputted. My first instinct with something like this is to remove the floors, the general strategy I though to solve this is remove the outer floor, then get rid of the square root, and then the inner floor. But I have no idea how to go about this or if this is even the right way to do it.  Help please? Thanks in advance. On  the delete notice is above, instead of below the close notice. Why is this happening? I understand this was made on purpose, but would like to know the reasoning. How do I transition to SSL without affecting PageRank? Here at Stack Exchange we're working on moving all traffic to SSL. The reason we're not doing logged-in-users only is that one side of the login divide would suffer a redirect from Google every time.  This happens because Google's only going to have http:// or https:// in the results, not both.  Aside from building the SSL infrastructure (), the outstanding question we have is: how do we best transition to SSL?  Here are the relevant bits of our plan (testing on small sites, moving up to stackoverflow.com):   Get SSL ready/enabled (but not linked to) on all domains Start rendering only the &lt;link rel="canonical"&gt; as https:// Start sending a 301 for all http:// requests to https:// (from our domains...of course we can't do anything about all the existing links pointing to us) After a transition period, set all user cookies as secure   So the endgame is having all content delivered over SSL and all HTTP requests redirected.  What we're primarily concerned with is how this will affect PageRank to our sites. We depend a great deal on traffic that comes from Google and want to ensure that doesn't take a dive as we start delivering more security to our users.  The only bits I've found on this that seem to be substantive are  on :     @Frank Yes, I'm certain that Google treats HTTP and HTTPS URLs as separate URLs for crawling, indexing and ranking (I work with the web-search team here at Google). Doing canonicalization with a 301 redirect like you mentioned is a great way to solve this :) –  Oct 23 '10   and the only webmasters video I could find:  The video doesn't have a solid answer, not one I'd base the future of a company on anyway.  Is our transition plan the best way to accomplish an SSL move, at least from an SEO perspective?  If there's other more recent or concrete advice around how a move like this affects Google ranking we'd love to hear about it. How many fixed points in a permutation I am taking a probability course and we have been of course learning the classic problems of men with hats or variations of that in some other form. The problems being of the type if $n$ men have $n$ hats and mix them all together, whats the probability $0, 1, 2,$ or $k$ men choose their hat.   But from what I can gather is that they are all problems of the same type, for any given random permutation of $k$ objects how many fixed points are there. My professor taught us to solve this using conditional probabilities (conditioning on whether the first person matched and then generating a system of equations) and using the inclusion-exclusion principle. But is there any other way to reason this? Modular exponentiation by hand ($a^b\bmod c$) How do I efficiently compute $a^b\bmod c$:  When $b$ is huge, for instance $5^{844325}\bmod 21$? When $b$ is less than $c$ but it would still be a lot of work to multiply $a$ by itself $b$ times, for instance $5^{69}\bmod 101$? When $(a,c)\ne1$, for instance $6^{103}\bmod 14$?  Are there any other tricks for evaluating exponents in modular arithmetic?  This is being asked in an effort to cut down on duplicates, see  and . How do you safely encode a URL using JavaScript such that it can be put into a GET string?  var myUrl = "http://example.com/index.html?param=1&amp;anotherParam=2"; var myOtherUrl = "http://example.com/index.html?url=" + myUrl;   I assume that you need to encode the myUrl variable on that second line? How to keep processes running after ending ssh session? Why aren't hash values for "nothing" (empty) defined as all zeros? Any decent hash algorithm will produce basically "random like" values for any given input including the empty input.  For example MD5 produces d41d8cd98f00b204e9800998ecf8427e on an empty input.  I wonder, however, why the MD5 algorithm wasn't defined to have a final step where the output is XORed with d41d8cd98f00b204e9800998ecf8427e. This should not affect the cryptographic strength of the hash algorithm, and it would have the convenient property that a hash of all zeros represented a zero input.  Would it simply just because adding that step would slow the hash down a bit? How exactly does curved space-time describe the force of gravity? When electric dipole placed in non uniform electric field, what is the approach to calculate torque acting on it? Can it be zero? Let $G$ a group with normal subgroups $M,N$ such that $M\cap N=\{e\}$.   i) Show that for every $m\in M$ and for every $n\in N$, $mn=nm$.   ii) If $G$ is generated by $M\cup N$ then $G\cong M \times N$.   This is an homework question for abstract algebra. I think I can prove $i)$. But I have no idea how to prove $ii)$. Can anybody give me a hint for this one ?    Here my proof for i): Let $n \in N$ and let $m\in M$. Let $x=mnm^{-1}n^{-1}$. As $N$ is normal subgroup, $mnm^{-1} \in N$. Therefore $x \in N$.  As $M$ is normal subgroup , $nmn^{-1} \in M$. Since $m\in M$, then $x=m(nm^{-1}n^{-1})\in M$. This implies that $c\in M \cap N$, then $c\in \{e\}$, then $c=e$, and we get $mn=nm$.