How should I configure SPF for my domain?
What are SPF records, and how do I configure them?
I am trying to grab the capital letters of a couple of words and wrap them in span tags. I am using  for extract and wrapping purposes, but it's not outputting anything.  preg_replace("/[A-Z]/", "&lt;span class=\"initial\"&gt;$1&lt;/span&gt;", $str) Review option on mobile phone not available? The other day I was looking at Stack Overflow on my Android phone. All is made very nice and all, but I could not find the Review button/link. Is it being implemented, did I miss it, or it is not available? I tried to fix my hard drive using Ubuntu but I encountered an error message and didn't know how to proceed. I need to fix my bad sectors   fsck /dev/sdb   fsck from util-linux 2.20.1   e2fsck 1.42.5 (29-Jul-2012)   fsck.ext2: Permission denied while trying to open /dev/sdb   You must have r/w access to the filesystem or be root Connect Error (2054) - mysql_old_password issue still not solved How to install Redis on Ubuntu 16.04? I am working with Laravel but i have installed all on my own (php, mysql, composer, nginx) and now i need to install Redis and configure it so i could use it for queue driver in Laravel.  How to install it, because it cannot be installed through apt-get install redis  i get this error:  ubuntu@ubuntu:~$ sudo apt-get install redis [sudo] password for ubuntu:  Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package redis I have a third-party library which consists mainly of a large number of static (.a) library files.  I can compile this into a single .a library file, but I really need it to be a single .so shared library file.  Is there any way to convert a static .a file into a shared .so file?  Or more generally is there a good way to combine a huge number of static .a files with a few .o object files into a single .so file? Why does $\lim_{n \to\infty}a_{n+1} = \lim_{n\to\infty}a_n$? Assume that $\{a_n\}$ is a convergent sequence. How to use the definition of a limit of a sequence to prove that $\lim\limits_{n \to\infty}a_{n+1} = \lim\limits_{n\to\infty}a_n$? C++: delete vs. free and performance $\mathbb Q[x]/(x^2+1)$ is not isomorphic to $\mathbb Q[x]/(x^2+2)$ I've got a qml file and I just want to ssh to the phone and do  qmlscene myfile.qml   Is it possible without doing all that stuff with SDK and packages? Just vim and some simple commands that can fit into person's memory. Solve for $f(x)$ if $f(f(x))=6x-f(x)$ Virtual box ubuntu: Internet not detected on guest(Ubuntu) in host(winXp) Convert a column into a comma separated list How to align content of a div to the bottom Say I have the following CSS and HTML code:    #header {   height: 150px; } &lt;div id="header"&gt;   &lt;h1&gt;Header title&lt;/h1&gt;   Header content (one or multiple lines) &lt;/div&gt;     The header section is fixed height, but the header content may change.  I would like the content of the header to be vertically aligned to the bottom of the header section, so the last line of text "sticks" to the bottom of the header section.  So if there is only one line of text, it would be like:   ----------------------------- | Header title | | | | header content (resulting in one line) -----------------------------   And if there were three lines:   ----------------------------- | Header title | | header content (which is so | much stuff that it perfectly | spans over three lines) -----------------------------   How can this be done in CSS? Break a previous commit into multiple commits OpenSource ATI driver - Fan running at full speed all the time I know this is a common problem and have read other topics but couldn't resolve. Anyways yesterday I found a solution - I have 2 graphic cards (hybrid) and they were both on. So I turned one off and installed Jupiter for power management and from there on the fans were quiet and I was happy as hell.  However (:)), yesterday evening I also updated the system and the fan and it's noise came back. I checked whether I am using only 1 graphics card and I am.  c0dehunter@mintBox ~ $ sudo lshw -c video [sudo] password for c0dehunter:    *-display                       description: VGA compatible controller        product: RS780M/RS780MN [Mobility Radeon HD 3200 Graphics]        vendor: Hynix Semiconductor (Hyundai Electronics)        physical id: 5        bus info: pci@0000:01:05.0        version: 00        width: 32 bits        clock: 33MHz        capabilities: pm msi vga_controller bus_master cap_list rom        configuration: driver=radeon latency=0        resources: irq:18 memory:c0000000-cfffffff ioport:c000(size=256) memory:fbcf0000-fbcfffff memory:fbb00000-fbbfffff   Maybe the problem is (false) temp reading from GPU?  c0dehunter@mintBox ~ $ sensors acpitz-virtual-0 Adapter: Virtual device temp1:        +44.0°C  (crit = +105.0°C)  k10temp-pci-00c3 Adapter: PCI adapter temp1:        +47.0°C  (high = +70.0°C)                        (crit = +115.0°C, hyst = +110.0°C)  radeon-pci-0200 Adapter: PCI adapter temp1:       +127.5°C     The thing that is weird is that if I boot into Windows the fan is still at full power (previously it wasn't). Did I f--- up my hardware with software? :)  //OH, yes - I forgot to mention that my laptop is not hot at all. The temps are about 50°C. I tried many ways to make a bigger screen in VirtualBox because I do not like the small size of the guest window? Is there is a way to make it big? Linear Transformations: Proving 1 dimensional subspace goes to 1 dimensional I am having trouble understanding this whole question, and how to prove it.  Let $F:\mathbb{R}^n\to\mathbb{R}^m$ be a linear transformation. Prove that if $L$ is a $1$-dimensional subspace of $\mathbb{R}^n$, then  $F(L)=\{y\in\mathbb{R}^m: y=F(x)\text{ for some }x\in L\}$  the image of $L$ under $F$ is a subspace of $\mathbb{R}^m$ with dimension $1$ or $0$. Hence prove that if the kernel of $F$ is $\{0\}$, then the image of $L$ is a $1$-dimensional subspace of $\mathbb{R}^m$ (and so, in this case, $F$ takes lines in $\mathbb{R}^n$ to lines in $\mathbb{R}^m$). The definition of derivative of a function $f(x)$ is $$\lim_{h\to0} \frac{f(x+h)-f(x)}{h}$$  Using this definition, the derivative of $\sin\sqrt{x}$ will be:  $$\lim_{h\to0} \frac{\sin\sqrt{x+h}-\sin\sqrt{x}}{h}$$  $$\lim_{h\to 0} \frac{\cos\left(\frac{\sqrt{x+h}+\sqrt{x}}{2}\right)\sin\left(\frac{\sqrt{x+h}-\sqrt{x}}{2}\right)}{h}$$  Now i got stuck. How to find the limit or simplify this expression?  I get intuition that we have to use $$\lim_{x\to0}\frac{\sin x}{x} = 1$$  but that too is leading no where. I am unable to remove h from denominator.  NOTE  I know the derivative of $\sin\sqrt{x}$ is $\frac{\cos\sqrt{x}}{2\sqrt{x}}$ using chain rule, but this exercise was given to us for practice using division quotient. PhD thesis without acknowledgements During the process of writing my PhD thesis, I was close to falling out with my adviser, the advice I received from other staff at the lab (including the director) was unhelpful at best. I have since made up with my adviser and have successfully defended the thesis. I now have to publish my thesis.  The department says that one can include acknowledgements. All of the theses I have seen in my lab and in my department feature acknowledgements. Due to this special situation,  I don't quite feel that acknowledgements are called for. Yes, my adviser helped during the first half of the project but then almost completely reverted his stance. In terms of contribution, it is my opinion that he comes out at 0%.  I do not want to address any of the issues in the acknowledgements. I do not think that this is the right place. Likewise, I do not feel like thanking any of the involved people. Therefore, I would just leave out the acknowledgements completely. In academia, is this considered worse than lukewarm acknowledgements? Should I actually care about the acknowledgement, because others do?