What is the language that appears on the first line of a script?
Does the shebang determine the shell which runs the script?
My eth0 has gone and I don't have internet and network connection I had internet connection, but when I upgraded my VGA and restarted my PC then everything for eth0 has gone.     When I used ifdown:     ifdown: interface eth0 not configured   Is there something I could do?    EDIT: Content of /etc/network/interfaces    auto lo iface lo inet loopback   When I ifconfig I don't have these lines:    inet addr:192.168.1.5  Bcast:192.168.1.255  Mask:255.255.255.0 inet6 addr: fe80::219:5bff:fe5e:a5e/64 Scope:Link   In the Terminal typed:  sudo gedit /etc/network/interfaces   and then added these lines in the bottom:  auto eth0 iface eth0 inet dhcp   then I typed:    sudo ifdown eth0 sudo ifup eth0   when I send the second command I received the below message:    No DHCPOFFERS received No working leases in persistent database - sleeping   Any help? Minecraft Laucher has no Versions So this if the first time this has ever happened too me and I was wondering what it is. I just downloaded Minecraft and there is no area where i can change my version too 1.8.9/1.7.10 all i see when I do it is blank  Im just Wondering on how come even tho i hit the Repair button on the minecraft.msi download it dosnt fix it... If there is a way too fix this let me know cause my friend wants too play and I cant cause of this.. Limit of $\frac{\log(n!)}{n\log(n)}$ as $n\to\infty$. Since many users are facing the NullReferenceException: Object reference not set to an instance of an object error in Unity, I thought that it would be a good idea to gather from multiple source some explanation and ways to fix this error.  Symptoms I am getting the error below appearing in my console, what does it mean and how do I fix it?  NullReferenceException: Object reference not set to an instance of an object Integral of $\frac{1}{(1+x^2)^2}$ I am in the middle of a problem and having trouble integrating the following integral:  $$\int_{-1}^1\frac1{(1+x^2)^2}\mathrm dx$$  I tried doing partial fractions and got:  $$1=A(1+x^2)+B(1+x^2)$$  I have no clue how to solve this since it is obvious there is no way to cancel out either $A$ or $B$ to get the other variable. Please guide me.  Thank you. I've found plenty of posts about changing the visibility of a block programatically.  My problem is the opposite. Given a block's ID/delta, how do I find out if it should be displayed at the current path?  I have a field collection that allows you to append a block using the Block Reference module (I preprocess the field collection and use my own template, so the logic has been taken away from the Block Reference module). It works, but I only want it to kick in if the "Show block on specific pages" rule says that block should be displayed. Prove that $R$ is a commutative ring if $x^3=x$ Let $R$ be a ring satisfying: $\forall x\in R, \; x^3=x$. Prove that $R$ is a commutative ring. Answer turned to CW, votes pre-CW era doesn't count in tag specific stat My understanding is that if an answer becomes CW (one way or another), original author gets to keep the votes pre-CW.  Does this also keep the pre-CW vote count for the tag-specific stat? It doesn't look like it, because I checked recently and suddenly my number dropped. It looks like the tag-specific stat just counts votes for non-CW answers, and doesn't "discriminate" between the pre-CW and post-CW era. If it's eventually CW, then it simply contributes 0 votes.  I'm fine with the fact that my answer became CW (in this case, through the question having 30+ answers), but I would like to keep the votes I earned before it did for the tag stat.  Otherwise I think the system is "broken". Someone can go posting 30+ answers to questions where Jon Skeet answered, and all of Jon Skeet's answers would become CW, and he'd then be 0 at all tags. Can you flash any android device with "fastbood flash" command (of the adb)? Test to see if the title length requirement can be circumvented by appending lots of dots. What are the differences between normal and classic difficulties? I can't seem to find a good list of info of all the changes that classic mode offers over normal other than that 'its much harder'.  Does any of the enemy AI improve in classic mode?  Do enemies have more health and do more damage?  Does the panic meter increase faster for countries? Why does water damage low-voltage microelectronics so easily? Everybody has had the time where water gets all over their electronics, and the whole thing gets ruined, like cell phones.  At that low of a voltage (3-5&nbsp;volts), I don't understand why it is such a short-term harm (long term makes sense - corrosion, etc.)  If an LED was in parallel with water, maybe a bit more current would be drawn, but it doesn't seem to be enough at all to short out the system, and the LED would still shine.  So what is it that permanently damages some electronics and what is the cause? Root of unity for $n+1$ Let $n \ge 1$ and $u_{1},u_{2},...,u_{n}$ are all root of unity for $n+1$ and there are different from $1$.(a) Find polynomial $f \in \mathbb R[x]$ of degree $n$ for which: $f(u_{k})=0$ for $k=1,2,...,n$.(b) Calculate real coefficient and imaginary part for $(2-u_{1})(2-u_{2})\cdot...\cdot(2-u_{n}).$    I have a knowledge about root of unity but I completely don't know how to do it because I think that I need some extra trick to do it but my ideas finished. I know that $\varepsilon_n^{(k)} = \cos\left(\tfrac{2k\pi}{n}\right) + i\sin\left(\tfrac{2k\pi}{n}\right) = e^\frac{2\pi i k}{n}$ and for $n&gt;1$ $\sum _{{k=0}}^{{n-1}}e^{{\frac  {2\pi ik}{n}}}=0$ but I think it is too little knowledge to solve this task.Can you help me? I was thinking of how to create an IV for a block cipher that doesn't require stored state, and I came up with the idea of using an HMAC of the (padded) plaintext and a (possibly distinct) key as the IV.  This seems to be secure:   The IV will only be reused if there is an HMAC collision or if the plaintext and key are the same.  The former would imply that the HMAC is broken and the latter is harmless, since it is just producing the output twice. The HMAC is verified after decryption, but before padding is checked, so padding-oracle attacks should not be an issue.   In particular, if the HMAC and the block cipher use different keys, there seems to be a very simple proof of security, assuming that either (1) the HMAC cannot be distinguished from a random function or (2) the block cipher is secure against maliciously-chosen (but unique) IVs:   The attacker cannot forge the HMAC, since this would require knowledge of the signing key. Since the signing and encryption keys are different in this case, and the HMAC is assumed random, malicious IVs cannot be triggered by an attacker.   Alternatively, if the cipher is secure against malicious (but unique) IVs, then the security of the cipher+security of the HMAC seem to prove the security of the system.  This (obviously) provides no protection against replay attacks, but that requires state anyway.  However, I am not a cryptographer so I do not trust my conclusions on this matter.  If this technique is secure, it would appear to be quite useful in practice, as it is simple and provides both encryption and authentication. Do vulnerability and resistance cancel out? Feature request: Add pronouns to usercards? I am aware there are many questions similar to this on MSE but I am having trouble following any of the solutions given.   I have the function given by   $f(x) = \dfrac{xy}{x^2+y^2}\;$ for $(x,y)\neq (0,0)$ and $f(0,0)=0$  I have calculated the partial derivatives and found:   $$\frac{\partial f}{\partial x} = \frac{y(-x^2+y^2)}{(x^2+y^2)^2}, \quad \frac{\partial f}{\partial y} = \frac{x(-y^2+x^2)}{(y^2+x^2)^2}$$  Now I need to show the partial derivatives exist for $(x,y) = (0,0)$.  I am also asked to show it is not continuous at $(x,y)=(0,0)$, based on other answers I've seen it seems like this follows from solving the first part but I fail to see how that follows through as well.   I could just copy the solutions with my function in place as I have seen a lot of answers using the definition of the derivative, but realistically I do want to understand what the thinking behind this is.   Any help would be appreciated. How to search the internet for terms with special characters As I learnt from this , Google has no ability to search for special characters. Let's say I want to search for ss!. Are there any other search engines that can achieve this? Please do not propose any programming code search engines since this is a general search. Content type permission to specific users How do I set content permission so that specific content types become visible/usable to the admin user only, while other content types may be visible by other user roles?  After I added new content types, I checked the rebuild permissions.   Content access is working fine but the problem seems to be the fact that the enw content types aren't made visible / accessible to the other roles... How do I add a new, valid tag when I don't have enough reputation? I'd like to post a question on StackOverflow, but I think I should be able to tag it with    . Poor me, there is no  tag; There is  and , I'm certainly not sure this is the right thing to do, so figure I'll start here.  Edit Question located here: