It seems that Server Fault explicitly disallows questions about networking outside the workplace. Is there a reason for that? Where should those questions go - ie  Where do you ask questions about networking/setting up routers/APs/Firewalls/etc for one's home.
I have just asked a question on   I read from this meta answer  that suggested     From a desktop support perspective there are certainly cases where a   large(r) number of machines will be affected by something, in which   case it's appropriate for SF. There are then others that are isolated   to a single computer, these tend to be the ones I vote to move to SU.   Since my question is clearly not about a single computer and is external to a single computer, I turned to ServerFault. I thought the question is about how to replicate a network admin strategy on my own (home) network. My question is, however, marked as off-topic, and I did see that homenetwork questions are off-topic. But this is not a single computer issue either.  My question is:  Where should such home/small network questions be asked?  What's the real difference between "professional" networks and the smaller networks that I build for my home or lab with a handful computers?  -- UPDATE --  The question asked here is different from the said duplicate question  as that question is about the difference among computer science and programming SE sites. It has nothing to do with network administration, whether it's large or small networks. None of the two SE sites in question (Server Fault and Super User) is even mentioned in the question or in the 2 cited answers.  -- UPDATE2 --  This question is not a duplicate of , which was cited in the OP and was the cause of this question. That question does not cover the overlapping area of small networks, which could both be for work and for home network.
Drop shadow for text in PGF/Beamer I want to really put an emphasis on some central piece of text I'm using in a Beamer slide.  I'm using tikz and overlay to put it, enlarged, on the center of the page, using the following code:  \begin{tikzpicture}[remember picture,overlay]   \node[at=(current page.center)] {     \scalebox{2}{\Huge\texttt{{This is important!}}}   }; \end{tikzpicture}   Can I add a drop shadow to the letter themselves, so they would look even more emphasized?  Is there some other decoration that can be added to the text itself, like a glow, etc.?  Or does PGF ignores node text altogether?  The text should be in typewriter style, so using special fancy fonts is probably not the solution. We have two sets: set No.1 and set No.2 as in this picture:   The observer is fixed to set No.1 . He sees set No.1 motionless and observes set No. 2 approaching with velocity 100,000 m/s.   Each set has one lamp and two, so called, touchers. Each set is designed so that if both touchers are touched simultaneously the lamp is turned on otherwise it remains off.  Set No. 2 is approaching set No. 1 so that each toucher in each set will be touched twice by the touchers of the other set.  The observer on set No. 1 observes the distance between touchers in each set 10 meters. He thinks the lamps on set No. 1 will be turned on because touchers in it will be touched simultaneously.  My question: Will the lamp on set No. 2 be turned on? How if an electrical current flowing from one toucher in a set to the other proves simultaneous touching? I was reading a textbook. I found that it was mentioned the speed of sound increases with increase in temperature. But sound is a mechanical wave, and it travels faster when molecules are closer.   But an increase in temperature will draw molecules away from each other, and then accordingly the speed of sound should be slower. How is it possible that the speed of sound increases if temperature increases? What is the relation of speed of sound and temperature? The question is to show that for any $x,y \in\Re^n$  $||x+y||\cdot||x-y||\le||x||^2+||y||^2$  with equality if and only if $\langle x,y \rangle= 0.$  I have that $||x+y||^2=||x||^2+2 \langle x,y \rangle+||y||^2$ , which helps me prove equality but I'm lost on how to show this and show that the inequality part. Forcing a SimpleXML Object to a string, regardless of context Find whether the integral converges or diverges. $$\int_{0}^{1}\frac{\log(x)}{1-x^2}dx$$  I simplified it to $$\int_{0}^{1}\frac{\log(x)}{(1-x)(1+x)}dx$$  Here I have $2$ "bad" bounds (both $0$ and $1$).  I think, to prove such integral converges, I should find something that is equivalent to or less than $\log(x)$ so I can exchange them, maybe $\sqrt{x}$, so it may cancel out the fraction, and I can compare it to $$\int_{0}^{1}\frac{dx}{x^p}$$  Also I had an idea to substitute $x$ with $u+1$ so I can use $\log(1+u) \sim  u$ when $u \rightarrow 0$. I'm allowed(not familiar with anything else) to use direct comparision test, limit comparision test, Cauchy test and Abel-Dirichlet's test.   Any hints are much appreciated, I just want to get the big picture.   Thank you. How to unmap TAB and do not make Ctrl-I invalid in VIM Picking a $\delta$ for a convenient $\varepsilon$? I'm studying some proofs in a book from the library  and  unlike my own book, it doesn't prove by showing that a certain expression is striclty less than $\varepsilon$ (given an  appropiate $\delta$ and $\vert x-a\vert &lt; \delta$, etc). Instead, it shows that it's less than some expression involving $\varepsilon$.   E.g. Given $\varepsilon &gt; 0$, we can pick a $\delta &gt; 0$ so $|f(x) - g(a)| &lt;  \text{insert stuff} &lt; k \cdot \varepsilon$ when $|x-a| &lt; \delta$, and thus $f(x) - g(a) \to 0 $ when $x \rightarrow a$.  How does this make sense formally? (Intuitively, I am convinced.)  I don't have much experience with $\varepsilon$-$\delta$ -proofs, so I might be missing something obvious. How to modify an array's values by a foreach loop? If a sequence converges in a metric space, it is Cauchy, and in $\mathbb{R}^k$ every Cauchy sequence converges.   Therefore, in $\mathbb{R}^k$ a sequence converges iff it is Cauchy.  Let $\{s_n\}$ be a sequence in $\mathbb{R}$ where each $s_n=\sum_{k=1}^na_k$. Therefore, by the above, every series converges iff  $$\left | \sum_{k=m}^n a_k\right| &lt;\epsilon$$ For a given $\epsilon &gt;0$ and an integer $N$ such that $N\le m\le n$. If $n=m$ then the statement reduces to:  A series converges if and only if $$|a_n| &lt; \epsilon $$ For a given $\epsilon &gt;0$ and an integer $N$ such that $N\le n$.  This clearly cannot be (e.g Harmonic series). When does the equivalence become an implication. What is a proper way to clean a 35mm negative film stripe before scanning?   What chemicals can remove fingerprints, dust that does not come off by blowing, or strains of glue? What type of cloth does minimal damage when rubbing off dirt? Let us say I have added a PPA that has X package that I want but it also has Y package that I do not want to use or receive updates from. How can I, from the same PPA, receive updates for a specific package but deny updates from the same PPA for other packages.  A step by step example would be good since this has happened to me in several PPAs that have a particular package I want but also add a whole bunch of others that I do not yet want to update. Suppose $f:X\rightarrow Y$ is a surjection and you want to show that there exists $g:Y\rightarrow X$ s.t. $f\circ g=\mathrm{id}_Y$. You need the AC to show this.  However, suppose $f$ is a injection and you want show there is $g$ s.t. $g\circ f=\mathrm{id}_X$. Then, according to my textbook, you don't need the AC to show this.  This is counterintuitive to me, because it's like you need a special axiom to claim that an infinite product of big sets is nonempty, while you don't need one to claim that an infinite product of singleton sets is nonempty, which seems smaller than the former.  So why don't you need the AC to show the latter?  EDIT: $X$ should be nonempty.  EDIT 2: I realized (after asking this) that my question mostly concerns whether the AC is needed to say that an infinite product of finite sets is nonempty, and why. Why does tmux set TERM variable to screen? Citing tmux man page:  The TERM environment variable must be set to “screen” for all programs running inside tmux.  New windows will automatically have “TERM=screen” added to their environment, but care must be taken not to reset this in shell start-up files.  Is this this because tmux session can be attached to any terminal (e.g. remote), screen being lowest common denominator? If I know my terminal, can I force it without unexpected results, or would some unsupported capabilities break (like scrolling)? I had a tin of golden syrup for a long time - longer than I care to admit. When I opened it up yesterday (to sweeten up some mulled wine), it was granular (a bit like honey can be), and black around the edges.   Is this 'bad', or just different?   Is the blackness the result of some chemical reaction with the tin?  And in general, does it eventually go off, or does it last indefinitely? Why is Euler's Totient function always even? I want to prove why $\phi(n)$ is even for $n&gt;3$.  So far I am attempting to split this into 2 cases.  Case 1: $n$ is a power of $2$. Hence $n=2^k$. So $\phi(n)=2^k-2^{k-1}$. Clearly that will always be even.  Case 2: $n$ is not a power of $2$. This is where I am unsure where to go. I figure I will end up using the fact that $\phi(n)$ is multiplicative, and I think I'll get a $(p-1)$ somewhere in the resulting product which will make the whole thing positive, as $p$ is prime implies $(p-1)$ is even. Can you create an illusion of empty space? I've been thinking of various ways for a crafty Illusionist/Rogue to 'hide in plain sight' by essentially creating the cover that they want to hide behind.  Ideas include things like:   Create a wall that is 2.5ft closer than it really is and hide in said space Create some innocuous barrier or container and hide within it Create a 'sheet' that essentially has what an empty room looks like 'painted' on it, so someone walking past an open door would see an empty room.   From different discussions I've had, these all should work, but the one lingering one I have is, what if my illusion is simply 'empty space'?  If I were to create an illusion of empty space and then place myself in it, would I be essentially invisible?  What if I created an illusion that was partially-empty space, like a 5x5 cube of swiss cheese? Would it seem like there was a swiss cheese cube formed around my person or could my 'fake-empty-space-image' fill the holes?  Would my 'empty space' illusion simply need to work like the aforementioned 'sheet of what I expect you to see' in order to function (and thus most likely only work from limited viewing angles)? For a distribution function $F(x)$ and constant $a$, integral of $F(x + a) - F(x)$ is $a$. For any distribution function and any $a \geq 0$, $\int_{-\infty}^{\infty} (F(x+a)-F(x))dx = a$.   In this case, "distribution function" means a right continuous function F with $F(-\infty) = 0$, $F(\infty)= 1$.   This problem comes after a section in the book on mathematical expectation, so I suspect I should use some property of expectation to prove it. Expectation appears to be something that applies to random variables, so I think I should be somehow transforming the problem into something in terms of expectations of random variables, but I'm not sure how. I know that given a distribution function, I can get a probability measure, but I'm not sure how to go from there to a random variable and actually get a relation between the expectation of the random variable and this integral. I'm sure whether this is the right way to go about this problem, but if it is, I'm missing a connection somewhere. My script (should) acts differently, depending on the presence of the data in the input stream. So I can invoke it like this:  $ my-script.sh   or:  $ my-script.sh &lt;&lt;-MARK     Data comes...     ...data goes. MARK   or:  $ some-command | my-script.sh   where two last cases should read the data, while first case should notice the data is missing and act accordingly.  The crucial part (excerpt) of the script is:  #!/bin/bash local myData; read -d '' -t 0 myData;  [ -z "${myData}" ] &amp;&amp; {     # Notice the lack of the data. } || {     # Process the data. }   I use read to read input data, then option -d '' to read multiple lines, as this is expected, and the -t 0 to set timeout to zero. Why the timeout? According to  (typing left unchanged; bold is mine):     -t timeout time out and return failure if a complete line of input is               not read withint TIMEOUT seconds.  The value of the TMOUT               variable is the default timeout.  TIMEOUT may be a               fractional number.  If TIMEOUT is 0, read returns success only               if input is available on the specified file descriptor.  The               exit status is greater than 128 if the timeout is exceeded   So I in case 2 and 3 it should read the data immediately, as I understand it. Unfortunately it doesn't. As -t can take fractional values (according to above man page), changing read line to:  read -d '' -t 0.01 myData;   actually reads the data when data is present and skips it (after 10ms timeout) if it is not. But it should also work when TIMEOUT is set to real 0.  Why it actually doesn't? How can this be fixed? And is there, perhaps, alternative solution to the problem of "act differently depending on the presence of the data"?  UPDATE  Thanks to @Isaac I found a misleading discrepancy between quoted on-line version and my local one (normally I do not have locale set to en_US, so help read gave me translation which I couldn't paste here, and looking up for on-line translation was faster than setting new env---but that caused the whole problem).  So for 4.4.12 version of Bash it says:     If TIMEOUT is 0, read returns               immediately, without trying to read any data, returning               success only if input is available on the specified               file descriptor.   This gives a little bit different impression than "If TIMEOUT is 0, read returns success only if input is available on the specified file descriptor"---for me it implied actually an attempt to read the data.  So finally I tested this and it worked perfectly:  read -t 0 &amp;&amp; read -d '' myData;   The meaning: see if there's anything to read and if it succeed, just read it.  So as to base question, the correct answer was provided by Isaac. And as to alternative solution I prefer the above "read &amp;&amp; read" method. Let $A$ be a UFD. Assume that $a,b \in A$ are relatively prime, $c \in A$ and $a | bc$. To prove that $a|c$, is the following approach correct (or do you have to use some type of prime factorization argument)?  By the relatively prime assumption, $\gcd(a,b)$ is a unit. Call that unit $u \in A^{\times}$. Then we can write $u = ax + by$ for some $x,y \in A$. But then, $c = c \cdot u = c(ax+by)=cax+cby$. However, it is clear that $a|cax$ and the fact that $a|bc$ implies $a|cby$. Thus, $a|cax+cby=c$.