Preface  I create a media folder structure with Python consisting of hundred of thousands symbolic links. This folder structure allows me to navigate my media files like in a complex application, e.g. Kodi, but on file system level. In order to avoid many disk write operations I create the links on a RAM drive. The disk is mounted as follows:  # sudo mount -t tmpfs -o size=100M none /mnt/mem   The Issue  After creating many links the script outputs the following error:  [Errno 28] No space left on device: '...'@78596   If I check the actual disk usage, it returns the following:  $ df -h // ... none            100M    1,7M   99M    2% /mnt/mem   So according to my system, only 2 % are used!  The system is:  $ uname -a Linux myServer 3.2.0-23-generic-pae #36-Ubuntu SMP Tue Apr 10 22:19:09 UTC 2012 i686 i686 i386 GNU/Linux   After some investigation my script is able to create up to 90,000 links.  The Weird  If I try to reproduce the error on my desktop, it works flawlessly. I'm able to produce over 1,000,000 links with no issues. I don't know the actual limitation.  The system is:  $ uname -a Linux myDesktop 4.15.0-76-generic #86-Ubuntu SMP Fri Jan 17 17:24:28 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux   The Questions   What limits the number of symbolic links in linux? Can I bypass the limitation by upgrading the OS? Can I bypass the limitation by upgrading to a 64-bit architecture?   Some deep insights would be welcome!  Thanks.
It is well-known that empty text files have zero bytes:    However, each of them contains , which according to my research, is stored in , and do use space.   Given this, it seems logical to me that it is possible to fill a disk by purely creating empty text files. Is this correct? If so, how many empty text files would I need to fill in a disk of, say, 1GB?    To do some checks, I run df -i but this apparently shows the % of inodes being used(?) rather than how much they weigh.  Filesystem             Inodes  IUsed    IFree IUse% Mounted on udev                   947470    556   946914    1% /dev tmpfs                  952593    805   951788    1% /run /dev/sda2            28786688 667980 28118708    3% / tmpfs                  952593     25   952568    1% /dev/shm tmpfs                  952593      5   952588    1% /run/lock tmpfs                  952593     16   952577    1% /sys/fs/cgroup /dev/sda1                   0      0        0     - /boot/efi tmpfs                  952593     25   952568    1% /run/user/1000 /home/lucho/.Private 28786688 667980 28118708    3% /home/lucho
I am using an external application to enter data into a Google Spreadsheet.  This workbook is then referenced by a separate workbook (with the IMPORTRANGE(spreadsheet_key, range_string) function) that manipulates and interprets the data.  My problem is that whenever I personally modify the referenced workbook, the referencing workbook updates just fine, but whenever the external application modifies it, it does not get updated.  I have tried editing the "Spreadsheet settings" so that recalculation is done every minute and on every change.  Furthermore, I have also installed an extension in Google Chrome that auto-refreshes the page every hour.  However, the data does not get re-imported from the referenced workbook.  Even if I copy the formula into a new cell, the data is still not re-imported.  Is there anything that I can do to the referencing workbook to trigger Google Sheets to re-import the data?  Edit: Just to be clear, I currently have one workbook with data entered by an external application in it (call it the "source sheet"), and another workbook with an IMPORTRANGE function in it (call it the "referencing sheet").  The data shown by the IMPORTRANGE function in the "referencing sheet" does not include any data entered by the external application since I last personally edited the "source sheet".  Also, both workbooks are using the new Google Sheets.  Edit: Also, this question is not the same as  because I am using the function given as the solution to that question to import data from a spreadsheet.  The problem is not how to import the data, but rather how to update the source for the data.  My assumption would be that Google would have taken care of this for me, but the data in the "referencing sheet" does not get updated, and the only way I can find to get it to update is to physically go into the "source sheet" and edit it myself. How to preserve custom number formatting after closing a workbook? The possessive 's in time expressions Which is the correct answer?         I'll be there in a _____ time.       A) day or two   B) day or two's   C) day's or two's A generic question across most board games: once a player has taken their turn (taken their finger off the piece they are playing), should they be allowed to change their mind?  Similarly, if a player forgets to take a privilege, such as an occupied building in Puerto Rico giving an extra worker, or plantation, if they remember a few moves later, should they be allowed to take the privilege?  Very few rules explicitly express how these events should be dealt with, so they are generally left up to the group. However, my group's rules will change depending on the personality of the players playing (not all members are available each time we play). I would like to make this consistent, and would appreciate feedback on how others deal with this scenario. Do adjustable length lightsabers exist in Star Wars universe? I always see blades of lightsabers have more or less the same length (dual blades are double). Why is that?  Can't a longer or shorter length be advantage in some case?    I am NOT expecting infinite length lightsabers (due to energy issues), but have we seen adjustable length blades in the Canon? How do simulacra behave? Notation for intervals I have frequently encountered both $\langle a,b \rangle$ and $[a,b]$ as notation for closed . I have mostly encountered $(a,b)$ for open intervals, but I have also seen $]a,b[$. I recall someone calling the notation with $[a,b]$ and $]a,b[$ as French notation.   What are the origins of the two notations?  Is the name French notation correct? Are they used frequently in France? Or were they perhaps prevalent in French mathematical community at some point? (In this  Bourbaki is mentioned in connection with the notation $]a,b[$.)      Since several answerers have already mentioned that they have never seen $\langle a,b \rangle$ to be used for closed intervals, I have tried to look for some occurrences for this. The best I can come up with is the article on , where these notations are called Czech notation and French notation. Using $(a,b)$ and $[a,b]$ is called English notation in that article. (I am from Central Europe, too, so it is perhaps not that surprising that I have seen this notation in lectures.) I also tried to google for  or . Surprisingly, this lead me to a  where this notation is used for open interval. Orthogonality of Hermite functions I would like to prove to myself that Hermite functions, defined by $\varphi_n(x)=(-1)^n e^{x^2/2}\frac{d^n e^{-x^2}}{dx^n}$, $n\in\mathbb{N}$ are an orthogonal system in $L^2(\mathbb{R})$, i.e. that, for any $m\ne n$, $$\int_{-\infty}^\infty e^{x^2} \frac{d^m e^{-x^2}}{dx^m} \frac{d^n e^{-x^2}}{dx^n}dx=0 $$ I have tried by integrating by parts as the book where I find such a statement, Kolmogorov-Fomin's Элементы теории функций и функционального анализа, says that it can be proved, but I am landing nowhere since I have no experience in manipulating such integrals... Thank you so much for any answer! How to find the joint PDF? How do I reset a sequence in Oracle? Is there a simple command for the available height in a beamer slide? Induction and electromagnetic fields I've got a few questions on induction and electromagnetic fields. My current understanding of induction and electromagnetic fields is that, when electricity/current flows through a wire, it creates an electromagnetic field. If you twist that wire into a coil then you can concentrate that field. You can then induce current into a different coil by placing it inside of the electromagnetic field created by the first coil.  So here are my questions:  Q1. Does the electromagnetic field contain any energy?  EDITED QUESTION  Q2. Electromagnetic fields are the same as waves, so does that mean that when current is induced, they get the energy from electromagnetic waves being exchanged, or do they induce current directly from the electromagnetic field?   Q3. If electromagnetic fields and waves are the same, then doesn't that mean that you can induce current from waves? Therefore transferring electricity over long distances?  Q4. What spectrum of light are the electromagnetic waves that are in a field created by electricity?  Q5. Finally, why is it not possible to induce current from the Earth's magnetic field? I thought Maxwell said that electric fields and magnetic fields were the same thing.   Thank you to anyone who answers.  Edited Q2: So my original question (although asked poorly) still stands. Where does the current that gets induced in the secondary coil come from? How does the electricity transfer from the primary coil to the secondary? For example, is it taken from the stored energy in the e.m field? Does the field just act as a bridge between the 2 coils? Or do the 2 coils exchange e.m waves which carry the electricity that is being transferred from coil 1 to coil 2? Or is it none of these things and something completely different? The other day I was trying to download something for Minecraft and it involved my bin folder. So I was looking for it and couldn't find it. I then thought that I might have accidentally deleted it, but didn't find it in the trash. I have no idea how to get the bin folder back with all the Minecraft binary files in them. Java version problem with Eclipse and NetBeans on 18.04 Creating mask file from shapefile using ArcGIS for Desktop? I have a shapefile of Lakes over my study area. Each polygon has attribute information of each lake, name, shape etc. Actually I want to eliminate all lakes from analysis. In other word, I want lakes to have 0 value and the area that out of boundary of lake to have their orginal pixel values. when I do subset using this shapefile, the output is not I want because my shapefile deoesn't have any value outer boundary of lake.   How can I build a proper mask file (inner part of lake has 0 value, outer is 1) using this shapefile in ArcGIS Desktop? Laptop randomly waking up = Hibernate / Low Battery? Program to create EMF that conserves transparency What open source tools allow for the creation of EMFs that conserve transparency in ArcMap?  I tried VeryPDF and Any DWG to Image Converter, neither on actually gave me a vector file that provided transparency.  Adobe Illustrator is a bit pricey when all I want to do is convert CAD blocks to vector symbols to use as ArcMap markers.  Anyone know of a good software for this purpose? Schwarz's Lemma, fixed points question This is from an old qualifying examination question.  If f is holomorphic in the unit disk $D$ and $|f(z)|&lt;1$ for all $z\in D$. Suppose also that $f$ has two distinct fixed points in $D$ then $f(z)=z$ for every $z\in D$  I know that I have to use the Schwarz's lemma and may be make use of Möbius transformations. I tried setting $g(z)=\phi_a\circ f\circ \phi_{-a}$. But that does not seem to work because I don't see why $|g(z)|=|z|$ for some non zero $z$.   Any helpful hints are greatly appreciated.  Edit: Of course the $a$ above is one of the fixed points. ISO image integrity check (new try)? When you open an .iso file with e.g. 7-zip, the tool lets you test the ISO file, just like you can test any RAR or 7Z or ZIP file that the file is still ok.  If that test finishes successfully, does that mean the .iso file data and all the files within the ISO disc image are fine and not corrupted (bitrot)?   I am a bit confused because elsewhere I saw it mentioned that the ISO (raw disc image) format doesn't contain any data integrity checksums, so I am unsure what the 7-zip tool is testing while testing an ISO disc image file. Sort and count number of occurrence of lines I have Apache logfile, access.log, how to count number of line occurrence in that file? for example the result of cut -f 7 -d ' ' | cut -d '?' -f 1 | tr '[:upper:]' '[:lower:]' is  a.php b.php a.php c.php d.php b.php a.php   the result that I want is:  3 a.php 2 b.php 1 d.php # order doesn't matter 1 c.php