I have seen on many occasions a name of a function (frankly speaking I just call it function because of it typical appearance, they are though sometimes named commands or system calls but I do not know the idea behind labelling them differently), which contains a number within the brackets part of it, like in exec(1) exec(2) exec(3).  What is the meaning behind putting numbers into them ?
So, for example, when I type man ls I see LS(1). But if I type man apachectl I see APACHECTL(8) and if I type man cd I end up with cd(n).  I'm wondering what the significance of the numbers in the parentheses are, if they have any.
Is there a way to determine what version (distribution &amp; kernel version, I suppose) of Linux is running (from the command-line), that works on any Linux system? Can I get US sales taxes refunded for electronics purchased while on vacation? I'm visiting the US for vacations (specifically Manhattan) and wanted to buy a digital camera.  The guy at the shop told me that I can get back what I pay in NYC taxes for that camera if I present the ticket at the airport, when I'll be returning home. And that this is not applicable to clothes but it does to electronic stuff.   Is any of this true? Greek numbering Theoretically if I were able to build some sort of device that let me sit 1 foot away from the surface of the Sun (or any star for that matter) without being vaporized, would a star produce any sort of audible sound at that distance?   From my understanding, sound waves need a medium to propagate through (air, water, etc).   Does this mean that all stars are completely silent (in the audible spectrum of frequencies at least) as they fuse  hydrogen into helium?   I know stars emit radio, xray, infrared, ultraviolet electromagnetic waves, but how about audible (20 Hz to 20Khz) frequencies?   For some reason it seems like this process would produce some sort of sound. how to concatenate string variables into a third? How to do "Files to store without compression" in 7-zip? Is there any way to selectively prevent certain file types from compression in 7-zip, like in WinRAR?  I'm trying to compress a huge folder (many gigabytes), and I don't want the already-compressed files (e.g. ZIP files) to be re-compressed -- they should be stored without compression. How can I run ssh-add automatically, without a password prompt? There are lots of questions tagged  that don't have a  response.  How do we interpret this? Is it because they are declined by default? We just have to wait for a response (the team is very busy)? Is Jeff the only one that reviews this questions?  I suppose the ones that have negative votes may (or may not) be declined by default, but there are quite a few with some to a lot upvotes that should have an official answer. I have an ArrayList&lt;String&gt;, and I want to remove repeated strings from it. How can I do this? Centering sections I am trying to create a schema page in LaTeX. It shall look like this.   How can I create schema code which look like this image? There should be also a click to go function. When the user clicks on the user_schema link he should be redirected to that page.  What classes I can use for this? Any suggestions would be appreciated.    \documentclass{article} \usepackage[utf8]{inputenc}  \begin{document} \maketitle  \section{User schema} \mySchema{Users} {     _id: ObjectId - Id do registro     name: String - Nome do usuário     date: Date - Data de Cadastro     ren_date: Date - Data de renovação do Cadastro     email: String - Lorem ipsum dolorsitamet, consecteturadipisicingelit, sed do eiusmodtemporincididunt ut labore et dolore magna aliqua. Ut enim ad minimveniam, exercitationullamcolaborisnisi ut aliquipexeacommodoconsequat. Duisautereprehenderit in voluptatevelit esse cillumdolore eu fugiatnullapariatur. Occaecatcupidatat non proident, sunt in culpa quiofficiadeseruntmollit.     access_log: Array [          {              date: String - Data da ocorrência.             user: ObjectId - Usuário que executou.             action: String - Ação Executada.         }         {              date: String - Data da ocorrência.             user: ObjectId - Usuário que executou.             action: String - Ação Executada.         }     ]     \link{group}{group_id}: ObjectId - Id do grupo. } \end{document}   Here is the image how should it appear: Equivalent statement of AC or not? Here's a corollary of AC stating that: if there exists an onto mapping $f:A\to B$, then there exists a 1-1 mapping $g:B\to A$. What I'm confused about is that whether or not  AC can be derived from this proposition, in return? I have tried but haven't found a proof. Any help would be appreciated. Why does $(g^b \bmod m)^a \bmod m = (g^a \bmod m)^b \bmod m$? I have been trying to understand why the diffie hellman key exchange algorithm works, specifically why the two exponents can be swapped in it without the result changing.   So my specific question is why:  (g^b mod m)^a mod m  = (g^a mod m)^b mod m  I am interested in the reasoning/proof/explanation behind why it is true.    Thank you Does the series $\sum \limits_{n=2}^{\infty }\frac{n^{\log n}}{(\log n)^{n}}$ converge? Past participle after noun: "proposed cost" vs. "cost proposed" I have the following two examples:        Our proposed cost is expensive.   Our cost proposed is expensive.      Is there any difference between them? Or is the second sentence wrong? Amongst the reasons for starting a bounty, one can select:     Reward existing answer      One or more of the answers is exemplary and worthy of an additional bounty.   Why not enable one to reward excellent questions in a similar manner? How many integers between $1$ and $10^4$ contain exactly one $8$ and one $9$? I have this problem: How many integers between $1$ and $10^4$ contain exactly one $8$ and one $9$?, but i dont know if $18, 19, 28, 29...$ serve, else it could be $8$ y $9 = 2$ numbers, help please. In how many ways can we pick three different numbers out of the group $1,2,3,\dots,100$ such that the largest number is larger than the product of the two smaller ones? (The order in which we pick the numbers does not matter.) Is there a performance difference between i++ and ++i in C? Is there a performance difference between i++ and ++i if the resulting value is not used? Prove that $\sqrt 2 + \sqrt 3$ is irrational I have proved in earlier exercises of this book that $\sqrt 2$ and $\sqrt 3$ are irrational. Then, the sum of two irrational numbers is an irrational number. Thus, $\sqrt 2 + \sqrt 3$ is irrational. My first question is, is this reasoning correct?  Secondly, the book wants me to use the fact that if $n$ is an integer that is not a perfect square, then $\sqrt n$ is irrational. This means that $\sqrt 6$ is irrational. How are we to use this fact? Can we reason as follows:  $\sqrt 6$ is irrational  $\Rightarrow \sqrt{2 \cdot 3}$ is irrational.  $\Rightarrow \sqrt 2 \cdot \sqrt 3$ is irrational  $\Rightarrow \sqrt 2$ or $\sqrt 3$ or both are irrational.  $\Rightarrow \sqrt 2 + \sqrt 3$ is irrational.  Is this way of reasoning correct?