Is the HP LaserJet PRO M130fw compatible with Linux?
How to install latest HPLIP on my Ubuntu to support my HP printer and/or scanner?
Does a Magic Staff count as a magic weapon? Many creatures have resistance to weapons that aren't "magic weapons".  A Magic Staff can be used as a quarterstaff, but (usually) doesn't have a bonus to hit (a "plus").  Is it considered a Magic Weapon for the purpose of damage resistance? I want to communicate between several computers on my network (static Ethernet), through SSH. In order to do that I need to run ssh-add every time I log in on a specific machine, how can I do it so that it's set up once and it doesn't ask me for the passphrase every time I log in or reboot my machine?  I know that there is a way that you should add some lines to the bash_profile file, but I still need to type the password every time I reboot/log in to a specific machine.  if [ -z "$SSH_AUTH_SOCK" ] ; then     eval `ssh-agent -s`     ssh-add fi Script to Notify me when something happens on a shared directory The situation is:  I have a shared directories from many other machines where other users work on.  I need to be notified whenever a user create, modify or delete a directory or file from his local directory which I share using smb...  It looks like the folder actions in the MAC systems..  Is there a software that do that?!  If there is no such application, any help in writing a script for that is appreciated..  Thanks in advanced... Over the past couple of days there have been a few questions about overlapping proposals and questions that could belong on multiple sites:        What is the best practice before / after asking a question if you think your question might be better on another site?  or  If I think my question might belong on multiple sites as per the above posts? Run a nohup command over SSH, then disconnect I want to execute a script, start.sh on a remote server which runs this:  nohup node server.js &amp;   Naively, I call SSH like this:  ssh myserver &lt;&lt;EOF ./start.sh &amp; EOF   This starts the script, but leaves the session connected. I want to follow this step with other commands in a script, so that's no good.  How can I SSH to the remote machine, launch a nohup command into the background, then disconnect? I suppose I could put the SSH process itself into the background, but that doesn't seem right. I can understand the choice of material, silicon 28, but why is it a sphere rather than (say) a cube? Article   I would have thought that a sphere would have been the hardest shape to machine accurately. Can I still use a usb flash drive after spilling water on it? So a few months ago I accidentally spilled a little water on a few of my usb flash drives. I really want to test and see if they work, but before I do, I just want to make sure that there's no risk of damaging my computer. I'm pretty sure it's fine, but I just got a new laptop and would hate to ruin it over something stupid. Start new chapter on same page I have just started special theory of relativity. The limiting speed known as speed of light fascinated me most. I asked my teacher:      Consider two massless objects moving in the same direction at the speed of light. What would be their relative velocity w.r.t each other?   My teacher tells me that their relative velocity would be zero. But then the speed of light is universal constant regardless of the motion of its frame of reference, so shouldn't their relative velocity be $c$? What is their relative velocity and how? Do objects moving at the speed of light obey law of addition of velocities? Proving the Cauchy-Schwarz inequality by induction I ran across this problem in some old notes, and I frustratingly can't figure out how to do it   Let $a_i$ and $b_i$ be sequences of natural numbers, use induction to show  $\sum_{i=1}^n (a_ib_i)^{1/2} \le (\sum_{i=1}^n a_i)^{1/2}(\sum_{i=1}^n b_i)^{1/2} $  Obviously this is trivial to show for n=1. I can't make much progress on n+1. I've tried various tactics, squaring both sides etc.   Any hint or help would be appreciated. Thanks. Sometimes a tag wiki excerpt or body ends up with unacceptable or useless content: plagiarized text that must be removed, or a totally unhelpful dictionary definition. (For example:  — and I've seen this situation many times before.)  The only way to get rid of that content is to submit replacement text that meets the minimum length requirement. This is not always easy as writing a decent wiki, and especially a decent excerpt, requires subject knowledge.  Currently the users or even moderators who are alerted to unacceptable content in a tag wiki cannot remove that content without providing their own, which they are not always in a position to do. Yet these wikis would be better off with no content than with either unacceptable or unhelpful content, or some content written by a non-expert in a hurry.  Please provide a way for users to blank a tag wiki excerpt or body. I'm not sure what the reputation requirement should be: same mechanism as for tag wiki edits (suggested edits with approval), or only done directly by a user with the trusted user (20k) privilege, or moderator-only. Can you tell me the difference in the meaning of the two sentences below?  As a defining relative clause.     The location which was called Central Park was a park in New York.    As a non-defining relative clause.     The location, which was called Central Park, was a park in New York. I had a bunch of errors in the output of sudo apt-get update:  duplicate entries and 404 not found errors.  Figured those out, I hope: I removed PPAs that didn't have any packages associated with them, then I removed out a duplicate entry in /etc/apt/sources.list.  It seems I have royally buggered it up.  Now most of the lines say Ign when I do sudo apt-get update.  How do I go about straightening out what I have screwed up?  I need to get rid of these Igns that are all over the place.  There are about 50% (eyeball guess) Igns! Is there a regular expression to validate an email address in JavaScript? How much money did Harry Potter have? So, we know Harry . By descriptions from the books, it looks like he had enough money to spend during his school years with plenty to spare for later life.  Is there an estimate on how much money he had? How much would that be in muggle money? Was he extremely rich?  I'm thinking here that he could have received more than just an inheritance. For example, anonymous supporters could have given him money through the bank while he was a baby, or when he was about to go to Hogwarts, and he wouldn't have known (not even Dumbledore would have known). How to round pixel values of a raster in QGIS? I have a raster with float number values for example: 2.544459104537964 and I want to round these up to integers. I have seen other posts on ArcGIS like  but when I use Raster Calculator in QGIS, Int(myraster + 0.5) only makes the first value (which is 0) to 0,5 and the last one (which is 100) to 100,5. The other pixels stay float. why ls reports a huge file and du does not? whether they are complete metric space All matrices which commute with all $2\times 2$ matrices I would like to find all matrices which commute with all $2\times2$ matrices.  I started solving problem in this way:    1) I have this matrix $A$ with real numbers: $$A=\left[\begin{array}{cc}a &amp;b\\c &amp;d\end{array}\right]$$ 2) Matrix which commute with matrix $A$ is matrix $B$: $$B = \left[\begin{array}{cc}e&amp; f\\ g &amp;h\end{array}\right]$$ 3) When i solve the equation $AB=BA$, I get this: $$\left[\begin{array}{cc}ae+bg&amp;af+bh\\ce+dg&amp;cf+dh\end{array}\right]=\left[\begin{array}{cc}ea+cf&amp;eb+df\\ga+ch&amp;gb+dh\end{array}\right]$$  How I can get the general look of wanted matrix? Second order partial of $f(x,y)=\frac{xy(x^2-y^2)}{x^2+y^2}$ Consider the function $f(x,y)=\dfrac{xy(x^2-y^2)}{x^2+y^2}$ for $(x,y) \neq (0,0)$, $f=0$ otherwise.  I have to compute $\dfrac{d^2f}{dydx}(0,0)$.  I know that I have to calculate $\frac{df}{dx}$ first. But that is ,  $\frac{df}{dx} = \frac{\partial f}{\partial y}\frac{dy}{dx}+\frac{\partial f}{\partial x}$. When I put it in wolframalpha, it gives me this calculation, and also just $\frac{\partial f}{\partial x}$ as an alternative form.   Why do I just ignore the y'? I don't know what y(x) is, as a function of x.  y and x are independent functions, no?