Different filesizes on different computers
`du -b` shows different size than `ls`
"Needs cleaned" or "needs to be cleaned" How to add click event to an element? Installing particular versions when repo has newer versions? Let's have a metapackage which depends on the following packages  Depends: A (=2),  B (=2),  C (=2)   Note the '=' - I want to install these particular versions, not the most recent ones.  Additionally:  B depends on A(>=1)  C depends on B(>=1) and A(>=1)  If the most recent versions of A,B,C in the repository are 2 then this works.  Since I have put version 3 of A and version 3 of B in the repo sudo apt-get install my-meta-package refuses to finish with the following info:  The following packages have unmet dependencies:   my-meta-package: Depends: B (= 2) but 3 is to be installed                    Depends: A (= 2) but 3 is to be installed   If I manually install versions 2 of A and B then the metapackage installs correctly, which strongly suggests that there is no hidden dependency on A3 or B3. This is not a solution for the problem as the metapackage is installed automatically on many machines.  QUESTION: What to do to make sudo apt-get install my-meta-package install versions 2,2,2?  Additionally, is there a way I could get an extended info what actually creates the need for version 3 of A and version 3 of B? Why time is considered a dimension? Why is time considered to be a dimension? And the other 7 (except the 3 dimensions of space, and the dimension of time) dimensions that string theory suggests, why can't they be realized? Prove that $(\mathbb{Z}_n , +)$, the integers $\pmod{n}$ under addition, is a group. Prove that $(\mathbb{Z}_n , +)$, the integers  $\pmod{n}$ under addition, is a group.  To show that this is a group, I know I need to show three things (in our text, we do not need to show that addition is closed-- rather, we show these three items):  $(a)$ Associative Law  $(b)$ Existence of Identity  $(c)$ Existence of Inverse  This is what I have been working with so far:     $(a)$ Associative Law:   First, assume that $n$ is a composite number and that $a,b \in \mathbb{Z}$ s.t. $a=nx$ and $b=ny$ for some integers, $x$ and $y$. Then $a+nx+nx=n(x+y)$.     So, this is where I am stuck for the Associative Law. I'm not sure if I am headed down the correct path to show that $\mathbb{Z}_n$ is associative.      $(b)$ Existence of Identity:   Generally, when showing the existence of an identity we can use this information for addition :  $a + 0 = 0 + a =a$.    I am unsure how to insert the modular portion of the definition into the existence of this identity. I realize that for addition, we generally look at $0$ (rather than $1$ for multiplication).     $(c)$ Existence of Inverse: I need to show that for each element $a \in \mathbb{Z}_n$ that $a^{-1}=-a$. Again, I do not know how to insert the modular portion of definition into this aspect of the proof.   My question is how to incorporate this modular information into the proof that this is a group. We have not covered the integers modulo $n$, binary operations, nor groups in my intro to proofs course. I am trying to read my text to figure out how to prove this, but have a difficult time reading and interpreting math speak. Is it possible to exclude questions I've already answered from the search criteria? Recently I asked if it were possible to find questions with just one answer and as a result we got an .  That's great, but ...     Is there a way to restrict the search to questions where that one answer isn't mine? That would help. :-)   It's certainly possible to search for , but it's not possible to exclude your own posts as far as I can tell:   -user:me searches for posts that . user:1-67 doesn't search for posts from user #1 to user #67, but searches for .  (And I'm not sure that will help anyway since I don't think it would be possible to simultaneously exclude 69-max(userID).) -Ericson searches for posts that , but since my last name is in the the metadata and not the searchable portion of posts: no joy.   And of course none of this will actually work to eliminate the questions that that I've answered already and want to ignore.  In general, If I'm involved in a Q&amp;A (or ) the notification procedures do a good job of keeping me up-to-date with developments.  But when I search, it's often to find questions I've not noticed before.  So being able to eliminate questions I have already answered would be a generally useful feature for me. Using a foreign driver's license in California when staying with a J-1 visa Definite Integral: $\int_0^1\frac{x^{2} -1}{\log x}\,dx$ How to figure out the following integral? I have not been able to solve it from some time. $$\int_0^1\frac{x^{2} -1}{\log x}\,dx$$ Background info: I am planning on making a filehost with which one can encrypt and upload files. To protect the data against any form of hacking, I'd like not to know the encryption key ($K$) used for a file, so the user will have to asymmetrically encrypt $K$ and send it as well. The reason for this double encryption is that you can still share (individual!) files with other accounts by encrypting $K$ with the public keys of those users, too.  My problem is: How can a user can get a public and private key without the server saving/knowing the private key and without the user having to remember a passphrase of 250 hex characters?  Question: Is there a way to derive a key pair from a password, like PBKDF-2 does for symmetric encryption? Suggestions on rearranging the cryptographic steps in an easier way are welcome, too.  Alternatively: It is also possible to encrypt the private key with a PBKDF-applied password and store it on the server, but I'd like to keep things 'simple'. ;)  Note: At this point I don't care if it requires RSA, ECC or an obscure cryptography scheme. If it was possible to dig a hole that went from one side of the Earth to the other... ...And you jumped in.  What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like it was up? I have a 2&nbsp;GB Kingston  card which is about three years old. I put it in a reader today in my Windows Vista computer, wrote a 32&nbsp;MB file onto it, safely removed it, and then tried to read it elsewhere. Nothing. Putting it back in the Windows Vista computer it now says:     You need to format the disk in drive F: before you can use it.   What should I do? I have access to many computers and OSes if your recommendations need that. I would be very sad if I lost all the contents of the card. Most of the data is backed up, but there are a few things that aren't. :(  Doing a   # dd if=/dev/sdg of=~/tmp/sd.bin   gives me a 2&nbsp;GB file, and  the file it seems like lots of my data is still there. How can I put it back together? How to create Unity indicators? I'm interested in Unity indicators and wonder if there is any tutorial on how to program them. I can use the sources of the existing ones as last resort, but I'd prefer a more friendly approach because my programming skills are quite limited. Joined pipelines Considering a routine such as this one:  alpha() { echo a b c |tr ' ' '\n'; }   which outputs a stream, I would like to take the output stream, transform it, and paste it with the original output stream.  If I take use upcasing as a sample transformation, I can achieve what I want with:  $ mkfifo p1 p2 $ alpha | tee p1 &gt;( tr a-z A-Z &gt; p2) &gt;/dev/null &amp; $ paste p1 p2 a       A b       B c       C   My question is, is there a better way to do this, preferably one not involving named pipes? How to turn particle emission on/off? Is there a way to animate whether or not a particle emitter is emitting particles at a given point in time?  I'm using the particle system to animate bullets, so basically I'm trying to find a way to say: at frame 150 the gun fires a burst until frame 170, at frame 240 it fires a burst until frame 265, and so on.  I've tried key framing the particle render setting between "object" and "none", but the problem with that is that the hidden particles are still there, so when the render setting switches to "object", the particles that were initially hidden suddenly appear.  I've also thought of putting a plane (not rendered) with a collision modifier in front of the emitter and then moving it when I want the emitter to start emitting particles.  Is there a better way? Equivalent of typedef in C# Is there a typedef equivalent in C#, or someway to get some sort of similar behaviour? I've done some googling, but everywhere I look seems to be negative. Currently I have a situation similar to the following:  class GenericClass&lt;T&gt;  {     public event EventHandler&lt;EventData&gt; MyEvent;     public class EventData : EventArgs { /* snip */ }     // ... snip }   Now, it doesn't take a rocket scientist to figure out that this can very quickly lead to a lot of typing (apologies for the horrible pun) when trying to implement a handler for that event. It'd end up being something like this:  GenericClass&lt;int&gt; gcInt = new GenericClass&lt;int&gt;; gcInt.MyEvent += new EventHandler&lt;GenericClass&lt;int&gt;.EventData&gt;(gcInt_MyEvent); // ...  private void gcInt_MyEvent(object sender, GenericClass&lt;int&gt;.EventData e) {     throw new NotImplementedException(); }   Except, in my case, I was already using a complex type, not just an int. It'd be nice if it were possible to simplify this a little...  Edit: ie. perhaps typedefing the EventHandler instead of needing to redefine it to get similar behaviour. How can I make iconv replace the input file with the converted output? I have a video that was rotated 180° when recorded. Is it possible to correct this with FFmpeg? Is there any way to see the custom messages/remarks of resolved/expired bounties? Location of /etc/fstab in El Capitan I want to activate the . But I can't find the /etc/fstab on my mac. osx 10.11.5 El Capitan Trichromelibrary was suddenly downloading from Google Play Store From nowhere, my friend got a notification that com.google.android.trichromelibrary was downloading together with a progress bar.  Why?