How to create/update OS level environment variable using the java programming?
How do I set environment variables from Java?
Cann I use a 19.5V 4.62A laptop charger for 19V 4.74A laptop? Reference undefined in \section with amsbook I have a section that is devoted to the proof of a theorem, and hence I used  \section{Proof of Theorem~\ref{thm}}   Of course, because of the headers that are capitalized, it asks for \ref{THM} when producing the header, and I get an obvious error. What is the proper way to handle such a case? Below is a MWE:  \documentclass{amsbook} \usepackage{lipsum} \newtheorem{thm}{Theorem} \begin{document} \chapter{First Chapter} \section{The Theorem} \begin{thm}[Lipsum Theorem] \label{thm} \lipsum[1] \end{thm} \section{Proof of Theorem~\ref{thm}} \lipsum[1-23] \end{document}   When compiling I get:  LaTeX Warning: Reference `THM' on page 3 undefined on input line 14.   (each time it produces a header), and the header shows     `2. PROOF OF THEOREM ??' How to capture the scene exactly as my eyes can see? What are underfull hboxes and vboxes and how can I get rid of them? In XFCE4 desktop environments, alt+scroll wheel zooms my entire desktop. I'm finding this very annoying because sometimes I flick the scroll wheel to go to the top of a document then press the alt key for a some unrelated keyboard shortcut and find myself zoomed in so far I can't see anything at all. Is there any way to disable this feature? I am moving from Malaysia to the US, and planning to bring my desktop computer with me. I plan to pack it in my checked-in luggage. Will the computer risk being damaged? Any precaution should I take to reduce this risk? Will there be any trouble with the airline or immigration about bringing computer? How can I make Firefox open magnet-links in Transmission? I can't find out how to make Firefox open magnet-links in Transmission.   There is no option to make it the standard program for magnet-links in its properties, and as I am not experienced with the filesystem so I can't add it as the standard program in Firefox either. Possible Duplicate:          There are several tarballs (e.g. Firefox, Eclipse, Zend Studio and ...) that have executable files in them, that we can extract and run. but this executable will be available only for the user that extracts it.  If we want to make it available for all users we should move it to some location like /usr/share, /usr/local/share/, /opt/, ... and give appropriate permissions, make an executable file in /usr/bin/ and so on...  I want to make a deb installer file that does them all! How to do it? $\mathbb{Q}^{\times}$ is the group of rational number without $0$ under multiplication, and $\mathbb{Z}^{n}$ is the free abelian group of rank $n$. Show that $\mathbb{Q}^{\times}$ not isomorphic to $\mathbb{Z}^{n}$. I tried to assume that there is an isomorphism and to get a contradiction.. didn't succeed Book or web site resources for an absolute beginner to learn about stocks and investing? I'm completely new to the world of investing and stocks. Knowing that I shouldn't invest or buy stocks until I know it well enough, I was wondering which cheap or affordable resources would be the best to get started?  I've seen quite a lot of books and websites that teach investing, but it's hard to choose.  To narrow it down, what book and/or what website would you recommend that does a good job teaching investing in stocks to beginners? Determinant of a square matrix in a field \begin{array}{rrrrr|r}     b &amp; a &amp; a &amp; \cdot \cdot \cdot &amp; a \\     a &amp; b &amp; a &amp; \cdot \cdot \cdot &amp; a \\     a &amp; a &amp; b &amp; \cdot \cdot \cdot &amp; a \\     \cdot &amp; \cdot &amp; \cdot &amp; \space &amp; \cdot\\ \cdot &amp; \cdot &amp; \cdot &amp; \space &amp; \cdot\\ a &amp; a &amp; a &amp; \cdot \cdot  \cdot &amp; b   \end{array}  I have the above matrix $A\in M_{n\times n}(F)$ where $F$ is a field and $n\geq1$, $a,b\in F$.  I'm trying to find out how to use row operations to make it into an upper triangular matrix in order to figure out the determinant. But I'm not sure how I would approach it. I have studied that every normed space $(V, \lVert\cdot \lVert)$ is a metric space with respect to distance function  $d(u,v) = \lVert u - v \rVert$, $u,v \in V$.   My question is whether every metric on a linear space can be induced by norm? I know answer is  no but I need proper justification.   Edit: Is there any method to check whether a given metric space is induced by norm ?  Thanks for help Can toddlers be taught to safely navigate stairs? I struggled with this over the weekend, and need to remap my mouse buttons. How do file permissions work? I'm listing some items for sale online, and have taken a bunch of pictures with my iPhone.  About half-way through the process, iPhoto '11 stopped downloading new photos into its local Photo Stream.  I've quit iPhoto and re-opened it.  I've gone into the Photos app on my iPhone and confirmed all the pictures are there.   Is this normal behavior? Is there any way to tell iPhoto to download my pictures? bash aliases equivalent for powershell? By default my Windows PowerShell starts in C:\Users\Santosh, my XAMPP installation is in D:\ so the htdocs folder is located at D:\xampp\htdocs. If I have to edit something in htdocs folder then I have to type full cd D:\xampp\htdocs\ (autocompletion is not so kind) then edit that file.  If this PowerShell were a Bash I would do this in .bash_aliases file:  alias htdocs='cd D:\xampp\htdocs'  Is it possible to maintain Bash aliases like file and alias any command in PowerShell? How can I backup my RAW photos while travelling without Internet access? I am following Carroll's GR book. He explain that it is convention to parameterize geodesics of photons by a parameter $\lambda$ such that  $$p^\mu ~=~ \frac{d x^{\mu}}{d \lambda}.\tag{3.62}$$  But this is the definition of 4-velocity for a massive particle in the case of $\lambda=\tau$ equal to proper time. My question then, is $$u^\mu = p^\mu$$ for all massless particles? I ask because it's well-known that proper time $\tau$ freezes for massless particles. umask in RHEL 6 How can one set the executable bit on files using umask? According to documentation, a umask of 000 should work, but in practice this only works on directories.  Also open to other methods of automatically setting +rwx on a particular user's created files if you have any.