I'm trying to install Ubuntu from a live USB but always encounter errors in the copying files installation phase.  The error message says that this I/O error are commonly due to faulty Medium or HDD. I'm checking my SSD and making a new Live USB to try again.  So this is my concern I can md5sum the ISO I download, but how do I check the live USB is good?
I downloaded the iso file for XUbuntu. I created a live usb using Pen Drive Linux. I turned on my computer, booted to the XUbuntu installation screen, and selected "check disk for defects".  A minute later, it says that it found one defect. How do I figure out what this defect is?
What does a "CALLBACK" declaration in C do? I was looking through some code from the  library and came across a function declared like this:  LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)   Now, I'm a Delphi coder.  No hablo C muy bien, senor.  But I remember enough syntax from my college courses to read it like this:  Function name is WndProc.  Argument list is pretty self-explanatory.  Function return type is LRESULT.  But what in the world is that "CALLBACK" doing there?  In Delphi, any function can be used as a callback; you just need to pass the right type of function pointer.  Is there any particular reason why C doesn't work that way?  Or does it mean something different? Comma — a punctuation error? Consider:     This book provides a solid psychological understanding of these experiments, and adds a few expansions and conclusions of its own. It also provides …   My question regards the comma. I have been told that having the comma there is an error.  According to  this seems to be the case according to “some style guides”. The reason is that the stuff after the comma is not independent; it’s dependent on what comes before.  What do you think? It would seem to me the comma helps a lot, because those two “and”s without any comma make the sentence rather cluttered. That’s why I put the comma there. So I’m not sure. Vortex in liquid collects particles in center At xmas, I had a cup of tea with some debris at the bottom from the leaves.  With less than an inch of tea left, I'd shake the cup to get a little vortex going, then stop shaking and watch it spin.  At first, the particles were dispersed fairly evenly throughout the liquid, but as time went on (and the vortex slowed, although I don't know if it's relevant) the particles would collect in the middle, until, by the time the liquid appeared to almost no longer be turning, all the little bits were collected in this nice neat pile in the center.  What's the physical explanation of the accumulation of particles in the middle?  My guess is that it's something to do with a larger radius costing the particles more work through friction... I would like to know if there is some way to share a variable or an object between two or more Servlets, I mean some "standard" way. I suppose that this is not a good practice but is a easier way to build a prototype.  I don't know if it depends on the technologies used, but I'll use Tomcat 5.5    I want to share a Vector of objects of a simple class (just public attributes, strings, ints, etc). My intention is to have a static data like in a DB, obviously it will be lost when the Tomcat is stopped. (it's just for Testing) bash profile works for user but not sudo How to install Epson Perfection V600 Photo Scanner drivers I'm looking for a good way to perform multi-row inserts into an Oracle 9 database.  The following works in MySQL but doesn't seem to be supported in Oracle.  INSERT INTO TMP_DIM_EXCH_RT  (EXCH_WH_KEY,   EXCH_NAT_KEY,   EXCH_DATE, EXCH_RATE,   FROM_CURCY_CD,   TO_CURCY_CD,   EXCH_EFF_DATE,   EXCH_EFF_END_DATE,   EXCH_LAST_UPDATED_DATE)  VALUES     (1, 1, '28-AUG-2008', 109.49, 'USD', 'JPY', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'),     (2, 1, '28-AUG-2008', .54, 'USD', 'GBP', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'),     (3, 1, '28-AUG-2008', 1.05, 'USD', 'CAD', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'),     (4, 1, '28-AUG-2008', .68, 'USD', 'EUR', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'),     (5, 1, '28-AUG-2008', 1.16, 'USD', 'AUD', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'),     (6, 1, '28-AUG-2008', 7.81, 'USD', 'HKD', '28-AUG-2008', '28-AUG-2008', '28-AUG-2008'); How to automatically restart a linux background process if it fails? food safety regarding re freezing twice cooked chicken I am defrosting a cooked chicken to use in a curry it will be thoroughly heated at a high temperature. If I have too much curry will i be able to freeze it, as the cooked chicken was frozen before? How can the Xenomorph see? If you just look at a picture of one there are no eyes readily apparent but they clearly know where they are going. Could their screeching be some form of echo-location? I see a new logo with CA at youtube.com. Does anyone know what it means? Pipe sound output to file? The following identity is true for any given $x \in [-1,1]$: $$\arcsin(x) + \arccos(x) = \frac{\pi}{2}$$  But I don't know how to explain it. I understand that the derivative of the equation is a truth clause, but why would the following be true, intuitively?  $$\int^{x}_{C1}\frac{1\cdot dx}{\sqrt{1-x^{2}}} + \int^{x}_{C2}\frac{-1 \cdot dx}{\sqrt{1-x^{2}}} =\\  \arcsin(x) - \arcsin(C1) + \arccos(x) - \arccos(C2) = 0 \\  \text{while } \arcsin(C1) + \arccos(C2) = \frac{\pi}{2}$$  I can't find the right words to explain why this is true?    Edit #1 (25 Jan, 20:10 UTC): The following is a truth clause: $$ \begin{array}{ll} \frac{d}{dx}(\arcsin(x) + \arccos(x)) = \frac{d}{dx}\frac{\pi}{2} \\ \\ \frac{1}{\sqrt{1-x^{2}}} + \frac{-1}{\sqrt{1-x^{2}}} = 0 \end{array} $$  By integrating the last equation, using the limits $k$ (a constant) and $x$ (variable), I get the following:  $$ \begin{array}{ll} \int^x_k\frac{1}{\sqrt{1-x^{2}}}dx + \int^x_k\frac{-1}{\sqrt{1-x^{2}}}dx = \int^x_k0 \\ \\ \arcsin(x) - \arcsin(k) + \arccos(x) - \arccos(k) = m  \text{ (m is a constant)}\\ \\ \arcsin(x) + \arccos(x) = m + \arcsin(k) + \arccos(k) \\ \\ \text{Assuming that } A = m + \arcsin(k) + \arccos(k) = \frac{\pi}{2} \text{ ,for } x \in [-1,1] \end{array} $$ Using Calculus, why is that true for every $x \in [-1,1]$?    Edit #2:  A big mistake of mine was to think that $\int^x_k0 = m \text{ (m is const.)}$, but that isn't true for definite integrals.  Thus the equations from "Edit #1" should be as follows: $$ \begin{array}{ll} \int^x_k\frac{1}{\sqrt{1-x^{2}}}dx + \int^x_k\frac{-1}{\sqrt{1-x^{2}}}dx = \int^x_k0 \\ \\ \arcsin(x) - \arcsin(k) + \arccos(x) - \arccos(k) = 0\\ \\ \arcsin(x) + \arccos(x) = \arcsin(k) + \arccos(k) \\ \\ A = \arcsin(k) + \arccos(k) = \frac{\pi}{2} \text{ ,for } x \in [-1,1] \end{array} $$ How to negate a specific symbol? I want to negate the symbol whose code is \models (this would be specific to Formal Logic). How can I do that? I tried a number of combination, but didn't find how this could be done. I tried \neqmodels, \nemodels, \notmodels, \nmodels  but all of them are wrong.  Is there a general way to negate symbols? Prove that $f\in L^1(A)\Leftrightarrow \sum_{n}^{\infty}m(\{ x\in A : f(x)\geq n \}) < \infty$ The phrase "let alone" I notice that "let alone" is used in sentences that have a comma. The structure of the sentence is what comes before the comma is some kind of negative statement. Right after the comma is "let alone," followed by the rest of the sentence.  What does "let alone" mean here? Does it mean the same thing as "or even?" Can someone explain this phrase and sentences that have it? I've had the ability to review suggested edits for a while now, however I don't often do so because the list is usually full of questions about languages and technologies I'm not familiar with or not interested in, and can sometimes be hundreds of questions long.  I would like to help out more, but most of my rep has been gained by questions within a specific technology, so I only feel comfortable reviewing edits within that tag.   Can you allow us to filter suggested edits by tag?  Edit:   Actually, can you let us filter the entire Review section by tag, and not just Suggested Edits?  I would find it much more interesting to review questions in tags I'm familiar with and can  understand the question content of, and it would give me a bit of pride to help maintain "my" section of SO. How do I get permissions to edit system configuration files? After I installed plank as my dock panel, I removed the default Ubuntu dock by running    sudo apt-get remove gnome-shell-extension-ubuntu-dock   Then Ubuntu dock is not on my desktop anymore, but when I open the application menu or Activities overview it is there, how can I hide it?  Removed dock shows on the left: I assume that the multimeter should read 2A, why is it only 0.358A? If this is how it is supposed to be, why? If I add a load, how do I measure that this load is being drawn, does the multimeter need to be in series?