I'm getting the following error on running sudo apt-get update :  sudo apt-get update                                                                 Get:1 http://dl.google.com stable InRelease 100% [1 InRelease gpgv 3,435 B] [Connecting to in.archive.ubuntu.com] [ConnectiSplitting up /var/lib/apt/lists/partial/dl.google.com_linux_talkplugin_deb_dists_stable_InReleaseIgn http://dl.google.com stable InRelease                                       E: GPG error: http://dl.google.com stable InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)   I tried:  $ cd /var/lib/apt $ sudo mv lists lists.old $ sudo mkdir -p lists/partial $ sudo apt-get update   But still getting the same error. Never faced this problem before. I was trying to install texlive-full and ran out of space during installation, apt-get install wasn't working then and gave the following output:  E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.   As per the answer here:  I tried:  cd /var/lib/dpkg/updates sudo rm * sudo apt-get update   And then this error occured. Now apt-get install is working fine but update isn't working. What is the solution?
I can use my mobile broadband to access Internet with Firefox but when I want to install any package from terminal or make 'apt-get update' command I got the following error:  got 'NODATA' (does the network require authentication?)   apt-get update output:  Get:1 extras.ubuntu.com trusty InRelease [213 B] 98% [1 InRelease gpgv 213 B] [Connecting to archive.ubuntu.com] Splitting up /var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_trusty_InRelease into data Ign extras.ubuntu.com trusty InRelease E: GPG error: extras.ubuntu.com trusty InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)    output of `cat /var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_trusty_InRelease  &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"&gt; &lt;html&gt; &lt;head&gt; &lt;title&gt;404&lt;/title&gt; &lt;meta http-equiv="Cache-Control" content="no-cache"/&gt; &lt;/head&gt; &lt;body&gt; &lt;p&gt; Not Found &lt;/p&gt; &lt;/body&gt; &lt;/html&gt;   output of wget:  wget -O - http://extras.ubuntu.com/ubuntu/dists/trusty/InRelease  --2014-06-01 09:23:35--  http://extras.ubuntu.com/ubuntu/dists/trusty/InRelease Resolving extras.ubuntu.com (extras.ubuntu.com)... 91.189.92.152 Connecting to extras.ubuntu.com (extras.ubuntu.com)|91.189.92.152|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 213 [text/html] Saving to: ‘STDOUT’   0% [                                       ] 0           --.-K/s              &lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"&gt; &lt;html&gt; &lt;head&gt; &lt;title&gt;404&lt;/title&gt; &lt;meta http-equiv="Cache-Control" content="no-cache"/&gt; &lt;/head&gt; &lt;body&gt; &lt;p&gt; Not Found  &lt;/p&gt; &lt;/body&gt; &lt;/html&gt;
Sum of real numbers that multiply to 1 I've seen a question in my math book with this explanation above it: "If the product of n positive real numbers is 1, then the sum of these numbers must be more than n". I was wondering if this is correct, and if it is, could someone give an explanation or a proof for it? What can cause "System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out"? What else, other than insert/update/upsert/delete, can cause "System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out"?  I've search the debug logs multiple times, and there absolutely is not a DML statement executed between the startTest and the failing callout.  Are there any other commands, or perhaps another callout (even though it's only an inquiry), that can cause this?  Does anyone know how to get around this problem? How does the British-Irish Visa Scheme (BIVS) work? I am an Indian citizen and have applied for the Standard Visitor visa to the UK, and wish to travel to Ireland by using the BIVS scheme.    Do I need to fill up a separate application for BIVS endorsement or is it handed out automatically?  Also, If I enter the UK, and then travel to Ireland, can I re-enter the UK again? Showing that $f:(0,2\pi]\to S^1$ is not a homeomorphism I want to show that $f:(0,2\pi]\to S^1$ defined by $t\to (\sin t, \cos t)$ is not a homeomorphism. I will do this by showing that its inverse is not continuous.    The inverse is defined by $(\sin t, \cos t)\to t$. So at $(0,1)$ we want to have $\lvert 2(1-\cos t)\rvert &lt;\delta \Rightarrow \lvert t-2\pi\rvert&lt;\epsilon$ for any $\epsilon$. If we take $\epsilon=\pi/2$, no matter how close $\cos t$ and $1$ are there will always be $t$'s close to $0$. So $f^{-1}$ is not continuous.  What do you think? Are there any mistakes? resolv.conf not working properly with Ethernet in Ubuntu I have a Lenovo X200 laptop on which I am running Ubuntu 9.10. Recently, (I assume after some updating, but I really don't know) my ethernet port stopped working under Linux. A more tech/linux-savvy friend of mine was able to temporarily fix the problem by manually editing the resolv.conf file with the DNS servers he found through his connection. However, after rebooting, the problem came back and now I am looking for a more permanent solution. What does the '=>' syntax in C# mean? I just came over this syntax in some of the questions in this forum, but Google and any other searchengine tends to block out anything but letters and number in the search so it is impossible to search out "=>".  So can anyone tell me what it is and how it is used? General way to determine $\mathbb{Q}(\gamma) = \mathbb{Q}(\alpha,\beta)$ given $\alpha$ and $\beta$ How can I stop the Devel module from generating blog/forum entries for Anonymous user? I'm using Devel's generate content feature to generate Blog/Forum entries for a site I'm working on and funny enough, I get to have a blog post by an anonymous user or forum topic by an anonymous user.  How can I stop Devel from doing this? I've only given Authenticated Users/ Administrators the permission to create a blog post or forum topic but still it generate for anonymous user. How can correct this? How to setup Squid Proxy (for localhost services and Tor and I2P) I have two partitions that I want to mount on startup: /dev/sda3   /mnt/devel  ext4    defaults    0   2 /dev/sda2   /mnt/excess ntfs    defaults    0   2  The ext4 partition mounts fine (owned by me, writable only by me), but the NTFS mounts owned by root with R\W permission for all. How to fix this? drwxr-xr-x  7 amanda amanda 4096 2012-03-14 19:07 devel drwxrwxrwx  1 root   root   4096 2012-03-14 22:38 excess how to create a roster sheet in sharepoint 2010 Table of contents numbering is strange I am a Saint Lucian and will be traveling to Manchester, UK soon about which I am a bit nervous.  Run Down:   I own a small business in my country (in the Caribbean), I have a certificate mentioning the details of the business from my Government. I pay rent in my country, but I do not have any loans (I hate owing). I pay life insurance in my country. I have a US B-1/B-2 visa (Visitor &amp; Business). I have visited the US once (last year November) on my US B-1/B-2 visa.   What I will be doing in the UK:   I plan to spend three months out of the six months which would be granted if I get leave to enter stamp. I plan to skydive in the first week and spend a few nights at an Airbnb. I plan to visit the Manchester Football Club stadium, I'm not the biggest of football fans but since I'm in Manchester, why not! I plan to do some more sightseeing and enjoy my time there. After the first week I will be staying with my female friend who owns an apartment for the rest of the time showing me around and helping me experience the UK lifestyle until June.   Why I'm leaving in June:   I am a WordPress enthusiast (I'm a Programmer) and WordCamp EU will be happening in France this year so I plan to fly from the UK to Paris where I will spend three days then take another flight from there to my country.   How my flights will be:   I will be taking a one-way Thomas Cook flight from my country to Manchester but will be purchasing my ticket for Manchester to France ahead of time so I could show Thomas Cook as well as Immigration that I don't plan to stay.   My concerns, could someone address them point by point please?:   I have a bank account but I just use it for collecting easy payments from my clients and pay for expenses. I store my savings in a credit union because of higher interest rates paid than the bank. When I applied for my US visa I showed a credit union statement showing my total balance. I'm seeing online that I should provide statements but these statements would look very bad since I my bank account is just for expenses... I mean it sometimes gets as low as $30 then, when my monthly earnings come in from clients, I withdraw savings to the credit union and leave what I need in the account for expenses. I read another post and it said people with bank statements showing poor spending might have difficulty but it's simply because the account is used for expenses not savings. For the later stages of my visit (after the first week) I will be staying with my friend. I will simply be staying with her to save on cost of Airbnbs for the next two months three weeks, even though they could be cheap, free is better right? I will be booking the Airbnb, skydiving and tours prior to traveling to the UK, will that help? Is my stay too long for staying with someone? I won't be depending on her for anything since I have my own funds...it's just convenient that she has a place where I could stay. If it is then I don't have a problem shortening my stay to 1-2 weeks and just head back to my country and take a separate flight to Paris in June.   I am nervous because I really want to visit the UK and see my friend, I am also not sure if the minimum amount of time that could be given to a visitor is six months? What if I get a round trip for two weeks and the Immigration officer gives me exactly two weeks stay, is that possible? Or is the minimum they could give six months?  Your help is very much appreciated, I want soon to try backpacking (nomad life) but I don't think my poor heart could take the stress of worrying about immigration :(  Update  Since people in the comments are asking about my relationship with the friend I plan to stay with even though she's from my country originally but now a UK citizens and we are simply friends. We've never had an explicit policy around downvoting -- users are free to, if they like, cast all their votes as downvotes. Whether this behavior is desirable or not is another matter.   Now, we do discourage downvoting by making downvotes cost -1 rep to the casting voter. But, there's nothing in our policy that says continual downvoting is bad or wrong or inappropriate.  However, my thoughts on this are changing. I no longer think it is community friendly behavior to cast an extreme number of downvotes, and I am considering an explicit policy forbidding it.  Some data points (as of today):  Total SO upvotes cast: 45,555,530  Total downvotes cast: 365,192  users with more than 100 downvotes cast: 596  users with > 100 downvotes and the lowest ratio of upvotes to downvotes:           |           |         | up:down user id | downvotes | upvotes |  ratio --------+-----------+---------+---------  187712 |       201 |      37 |    0.18    2525 |       580 |     149 |    0.25  136829 |       137 |      43 |    0.31   55943 |       438 |     140 |    0.31   19405 |       236 |      94 |    0.39    5640 |      3299 |    1337 |    0.40  180659 |       126 |      66 |    0.52   78613 |       348 |     198 |    0.56   39892 |       181 |     109 |    0.60     432 |       310 |     197 |    0.63  238704 |       198 |     132 |    0.66   12643 |       170 |     116 |    0.68   18256 |       219 |     152 |    0.69  122428 |       167 |     118 |    0.70  118854 |       120 |      86 |    0.71  105662 |       273 |     201 |    0.73  187690 |       135 |     101 |    0.74    1782 |       573 |     430 |    0.75   (this is a complete list, there are no more below this threshold.)  Based on this data I am leaning towards enforcing a "no more downvotes may be cast" if    You have at least (n) votes cast total Your upvote to downvote ratio is lower than ~ 0.5 We have a restricted Windows 7 computer that hides and prevents non-admin users from accessing the C Drive using the following policies:       However, they are able to circumvent this by typing the following into Explorer: \\localhost\C$  How can I disable this path but allow other UNC paths. For example they are allowed to access a shared folder on a different computer. eg. \\192.168.2.1\SharedTransfer  Note: Simply Enabling the Group Policy: Remove Run menu from Start Menu will not work as this blocks all UNC paths.  Update  The user, called Site User, is not a member of the Administrator group directly or indirectly. It is only a member of the group Users.  Accessed the following from: Control Panel\All Control Panel Items\Administrative Tools\Computer Management (Local) &gt; System Tools &gt; Local Users and Groups   Local Users and Groups  - Groups       - Administators              - Administrator              - Service User (our admin user)       - Users              - NT AUTHORITY\Auntenticated Users (S-1-5-11)              - NT AUTHORITY\INTERACTIVE (S-1-5-4)              - Site User (user account in question) Attacks of the MAC construction $\mathcal{H}(m\mathbin\|k)$ for common hashes $\mathcal{H}$? Consider a common practically-collision-resistant hash function $\mathcal{H}$ (e.g. , , , ), perhaps based on the  as are the first three. We define a  $\mathcal{C}$ $$(k,m) \mapsto \mathcal{C}(k,m)=\mathcal{H}(m\mathbin\|k)$$ where $\mathbin\|$ denotes concatenation, $k$ is a secret key (constant, or at least of fixed size), and $m$ is a message (possibly of variable length). Assume that an adversary can (iteratively) submit queries with $m_j$ and obtain $C(k,m_j)$, and wants to obtain $k$ or otherwise compute $C(k,m)$ for some $m\ne m_j$.  That MAC $\mathcal{C}$ is not trivially bad. In particular, if $\mathcal{H}$ was indistinguishable from a random function in the , $\mathcal{C}$ would be secure. And even though $\mathcal{H}$ may have the , it does not turn into a devastating attack on $\mathcal{C}$.  The less impractical generic attack that I see is that if a collision was known for $\mathcal{H}$ with the colliding messages of moderate identical length, it could be deduced countless collisions for $\mathcal{C}$. Hence security is demonstrably not better than collision-resistance of $\mathcal{H}$ (for identical-length messages). We could assume that $k$ is half the size of the result of $\mathcal{H}$, and hope that the security is about  or  or , 280, 2128, 2256 hash rounds for SHA-1, RIPEMD-160, SHA-256, SHA-512.   What are the known attacks against $\mathcal{C}$ (better than the above), and their cost, for each of these common hashes?  Is there hope for an argument that an attack against $\mathcal{C}$ would turn into an attack of similar cost against $\mathcal{H}$, or hint of the contrary?  Update: this  is of interest, but I fail to find that it really answers the present question.  Update 2: I am aware that the construction considered is weaker than , and in particular is vulnerable to collision on $\mathcal H$; I stated that, and that it is thus pointless to have the key wider hopeless to target security against some attacks better than half the hash's size. I'm asking exactly what cryptanalytic attack better than finding a collision on $\mathcal H$ there are. There is room for such an attack only by exploiting a weakness in the structure or/and the round function of a concrete $\mathcal H$. How to make a complete factory reset, without anyone being able to retrieve my data? I will have a few Android phones that I will have to let go.   I would like to make a proper clean wipe of the data, without no one being able to retrieve them, and do a factory reset.  I have read about the , encrypting the device before doing a factory reset, doing both, etc.  Since I am not an Android/adb guru, I would like to know if some of you would have some idea on how to achieve this with certainty.  I know "certainty" is a big word when it comes to proper data erasure on flash memory but still.  I have found some answers here and somewhere else, saying that encrypting and doing a factory reset on your Android device is enough, but I could not find a reliable source.  Just a few information that could be useful:   I'm running Linux as my OS and, therefore, I'm not looking for a Windows-based solution My devices are non-rooted and (almost) identical (Samsung A510F + 1 A510FD) Is the Star Wars Universe just one galaxy? I have question about ArcGIS and python script. There are following sample code, So I would like to change Another Field , not OIDFieldName. Please let me know how to change Another Field.  import arcpy import itertools  arcpy.env.workspace = r"C:\path\to\workspace"  base_shapefile = "some_shapefile.shp"  oid_field = arcpy.Describe(base_shapefile).OIDFieldName feature_count = int(arcpy.GetCount_management(base_shapefile).getOutput(0))  for (i, j) in itertools.combinations(range(feature_count), 2):     arcpy.Select_analysis(base_shapefile , "combination_%i_%i.shp" % (i, j), '"%s" in (%i, %i)' % (oid_field, i, j))   These sample code is combination for 5C2. I want to create all combiantions 5C3 , 5C4 , 5C5. GCD in a PID persists in extension domains