Is it possible to create a virtual file in unix, whose contents are determined programmatically when the file is accessed, a bit like the files in /proc?  For example, I have a program that retrieves a particular setting by reading/catting a file. However, rather than store that setting directly in a plain text file, I want to be able to retrieve that setting from a database in the background and then pass that information to the program when it reads this virtual file. Is it possible to do so?
Is there any way to create a virtual file, such that reading from the file actually reads from the stdout of a command; writing to the file is acually writing to the stdin of a command?  So far I have kludged this with an inotifywait on a file, which calls a command when the file is modified, taking it's input from the file and writing back to it.  I don't like that the inotifywait has to be constantly restarted though (and I have to ensure that it is always running). I only use this file perhaps twice a week.
If $f:[a,b]\to \mathbb{R}$ is continuous and nonnegative and $\int_a^b{f}=0$, then $f(x)=0$ for all $x\in [a,b]$ How do I install the VirtualBox version from Oracle to install an Extension Pack? Deactivate all \alt,\uncover in beamer (for printing) I have a big latex beamer that uses \alt, \uncover, ... to create "animations".  My goal is to deactivate all these commands temporary (let's say : just use the last state/slide each time there's this kind of thing) to print my document.  Is there a global command to do this or have I to do all this manually (comment manually the commands / or (simpler but still really long) suppress manually pages from the output) ?  Thanks very much in advance for your help. Do spellcasters know when a dismissable spell has been broken? Do spell casters know how long their spells are active, and can they tell at a glance?  Specifically lets talk about , as I know its a permanent duration and dismissable. Does the spell caster who put someone under this spell know how long it is active? Could they tell automatically just by seeing the person (without any clues like them walking in a maze without difficulty or reacting to a sound)? So could they tell if someone has broken the spell they cast? Determinant of a $2\times 2$ block matrix I would like to know the proof for:  The determinant of the block matrix $$\begin{pmatrix} A &amp; B\\ C&amp; D\end{pmatrix}$$ equals $$(D-1) \det(A) + \det(A-BC) = (D+1) \det(A) - \det(A+BC)$$ when $A$ is a square matrix, $D$ is a scalar, $C$ is a row vector and $B$ is a column vector.  I appreciate your help. What is the pronunciation of "the"? I read that the definite article is pronounced differently depending on the word that follows it.  Which is the exact pronunciation of the? Share wireless Internet connection through ethernet I want to share the wireless Internet connection on my desktop with my old laptop, through ethernet.  I have ticked the option "Make available to others" on both connections, on my desktop, but my laptop doesn't connect. Am I doing something wrong or is it a bug? $ is not a function in drupal 7 theme On Takodana,      the main characters and various bar patrons can see the planet Hosnian Prime being destroyed by Starkiller Base with their (respective) naked eyes. How did they see this? Is the Hosnian system close enough to see? If it's not very close and they could just see the explosion, how did the light from it reach them so quickly? Why does parseInt yield NaN with Array#map? From the :  [1,4,9].map(Math.sqrt)   will yield:  [1,2,3]   Why then does this:  ['1','2','3'].map(parseInt)   yield this:  [1, NaN, NaN]   I have tested in Firefox 3.0.1 and Chrome 0.3 and just as a disclaimer, I know this is not cross-browser functionality (no IE).  I found out that the following will accomplish the desired effect. However, it still doesn’t explain the errant behavior of parseInt.  ['1','2','3'].map(function(i){return +i;}) // returns [1,2,3] If an polynomial has a complex root, is it necessary that its conjugate is also a root? If an polynomial has a complex root, is it necessary that the conjugate of that root is also a root of the polynomial? I am not sure about this. Please comment on this. How to install Windows 10 Home 19018 update? I'm using windows home edition, I have the latest update installed 1909.  I want to install docker for windows 10 home edition. It keeps saying  Docker Desktop requires Windows 10 Pro/Enterprise (15063+) or Windows 10 Home (19018+).  Should I join Windows insider? How long should I wait for that update to be released if I don't want to join windows insider? We are always introduced to magnets by pictures illustrating a parallepiped magnet, a horseshoe magnet, etc... Anyway the first time we actually calculate a magnetic field is for eelectromagnets. Indeed I've rarely seen explaining or calculating the magnetic field of a permanent magnet. I know formulas for the magnetic field of a moving charge, around a conductive wire, inside a solenoid, but I don't have idea on how to go about calcualting the filed of a simple permanent magnet. It's like that without the help of electricity I'm stuck. I'd guess it would be heavily dependent on the magnetic material, its shape and the medium in which is placed. I hope that someone would provide me some insights on why such formulas are  never introduced in most physics courses and lay down some examples of a permanent magnet field caluclation. My Granddaughter has lost/forgotten her ID and passwords for her iPad. When the iPad powers on, it goes straight to an iCloud password request and I cannot get past it.  I have installed iTunes on my laptop but it fails to connect to the server (error 310).  I installed iCloud control panel and tried a restore but that failed because of "Find my iPad" was active, which I cannot turn off because of the original password problem!  This is driving me crazy. I just want to reset everything now so that I can hand it back to her. Can anyone help? Convert list of ints to one number? I have a list of integers that I would like to convert to one number like:  numList = [1, 2, 3] num = magic(numList)  print num, type(num) &gt;&gt;&gt; 123, &lt;type 'int'&gt;   What is the best way to implement the magic function?  EDIT  I did find , but it seems like there has to be a better way. I have a blender file where a sphere is orbiting a force field. I want it to be more red when it's closer to the center, and more blue when it's further. I already have the math figured out, I just need to know how to get x/y coordinates in nodes.  Here's the file: If I call finalize() on an object from my program code, will the JVM still run the method again when the garbage collector processes this object?  This would be an approximate example:  MyObject m = new MyObject();  m.finalize();  m = null;  System.gc()   Would the explicit call to finalize() make the JVM's garbage collector not to run the finalize() method on object m? I have a large table that is already partitioned by an identifier (CustomerId). I have created new customers, and want to add new partitions to the table, and want to confirm the correct way to do this. My predecessor set this up and is no longer available so I cannot confirm.  There are currently partitions for 60 distinct CustomerIds (let's say 1-60), and a filegroup and file for each. I have created new filegroups and files for the new customers (61-68) and need to partition the existing data already in this table. So, the data that's already in the table, with customerId 61-68 needs to be moved into separate partitions.   I tried to use the partition wizard, but couldn't find an option for what I wanted. As far as I can tell, I need to run something like:  ALTER PARTITION SCHEME PS_Details  NEXT USED Filegroup61 ALTER PARTITION FUNCTION PF_Details ()  SPLIT RANGE (61)   I'm looking for someone to point me in the right direction as to best practice for this sort of thing. Do I take the data out of the table, into a new table stored in the Filegroup61 then switch the partition in? Not really sure how to approach this. Suppose I am given a $2$x$2$ matrix $A=$ \begin{pmatrix} a &amp; b \\ c &amp; d \end{pmatrix}  And an initial vector $x_n$ = \begin{pmatrix} x_0 \\ y_0\end{pmatrix}.  Under repeated iteration $x_{n+1} = Ax_n$, we find that $x_{n+1}$ converges to a line in the direction of the $eigenvector$  of $A$ of the form $X$= $[u,mu]$ where $m$ is the slope of the line.  I know that this process somehow also involves the largest $eigenvalue, \lambda,$ of $A$, though I am unsure how it connects.  My question is: How does the largest eigenvalue connect to this repeated iteration, how do I find the slope of the line of convergence $m$, and what is meant by the "direction of the eigenvector"? Can I use the Adwaita theme in Unity without installing GNOME shell? I recently installed Ubuntu 11.10 (new install). I would like to use the Adwaita theme with Unity, but it seems that it is not available in the theme selection dialog. I know I get it there after installing gnome-shell, but is there a way to use Adwaita theme for Unity without installing gnome-shell?