Sudden proliferation of 'Too many open files in system' errors. Can't do backup
Which command controls the open file limits?
General closed form of $\int_{0}^{\theta_0} \frac{1}{\sqrt{\cos \theta-\cos \theta_0}} d\theta$ I once asked a  about how to integrate the reciprocal of the square root of cosine.  Is  there a general closed form for the integral $$\int_{0}^{\theta_0} \frac{1}{\sqrt{\cos \theta-\cos \theta_0}} d\theta$$   in terms of the gamma function?  Thank you. As we all know, going near a black hole (Gargantua in this case) slows down time, according to the theory of relativity.  So when Cooper comes out of the black hole, after spending a fair bit of time there, shouldn't he be much older than Brand who hasn't gone inside Gargantua? I've tried to install Ubuntu on a VMWare Virtual Machine, but it never gets past the  bootloader :  ISOLINUX 4.01 debian-20100714 ETCD Copyright (C) 1994-2010 H. Peter Anvin et al No DEFAULT or UI configuration directive found! boot: _   I've also tried to burn this .iso image to a CD and go from therem but I got the same problem.  Some more details :   VMWare Server 2.0.2 Build 203138 on Windows 2008 R2 ubuntu-10.10-desktop-i386.iso image used (downloaded yesterday evening) Why shouldn't I use "Hungarian Notation"? How to show $ \sin x \geq \frac{2x}{\pi}, x \in [0, \frac{\pi}{2}]$? I have tried the following: $$ f(x) = \sin x-\frac{2x}{\pi} \\ f'(x)= \cos x-\frac{2}{\pi} \\ f''(x) = -\sin x \leq 0 $$ But this doesn't seem to be heading in the right direction as it would appear $f'(x)$ is decreasing and has a zero within the domain, so I'm not sure how this might be used to prove the inequality. How can I prove that all rational numbers are either terminating decimal or repeating decimal numerals? I am trying to figure out how to prove that all rational numbers are either terminating decimal or repeating decimal numerals, but I am having a great difficulty in doing so. Any help will be greatly appreciated. I had opened a terminal to install macchanger via sudo apt-get install -y macchanger, and then entered my password. It stated that macchanger was already the newest version, so I typed clear and then ran:  sudo ifconfig eth0 down   which is when this error message appeared:  eth0 ERROR while getting interface flags: no such device   This is a laptop and I am connected via ethernet cable.  How can I resolve this, so that I can run macchanger?    So I used ifconfig -a and I'm looking but seeing no mention of  eth0  The interfaces that are showing top to bottom are:  enp58s0f1 lo tun0 UNSPEC wlp59s0   The only reference to ethernet is the MAC and also txqueuelen   Does this help in figuring what I need to do to get this sorted? Evaluate $\int_0^\infty\frac{\ln x}{1+x^2}dx$ Evaluate $$\int_0^\infty\frac{\ln x}{1+x^2}\ dx$$ I don't know where to start with this so either the full evaluation or any hints or pushes in the right direction would be appreciated.  Thanks. How do hashes really ensure uniqueness? This might seem an impractical and unnecessary conversation, but I feel it's something I need to clarify. Especially, as I just got my first developer job in a blockchain startup.  So hashes are said to generate the same thing for any information it sees, and it's only a one-way interaction.   As far as I understand, hashes are just long alphanumeric strings. If one computes hashes across all documents, keys, information, files, etc, over and over again- it's simply a matter of time until the same combination comes up again for different information (applying it across all possible contexts)? This might be an impractical test given size and possibility, yes, but is it this that makes hashes powerful, that it's practically impossible to recreate a hash that for any foreseeable endeavor it's fine, or is there some element that I'm missing that reduces even that extremely low probability to zero? Is there any design constraint that prevents a very powerful computer to back-calculate the original data from a hash? Or is it simply that the design is so complex that it's simply a futile exercise to dream of such a large computer required for this task? What's stopping a hacker or malicious middle man to hack open the software program or library that creates this "hash" and then use that library to create hashes of his/her own or mislabel some target company's hash with his/her own pointing to their version of the file? Especially since many applications, languages, and developers use hashing independently. Whichever is most weakly secured, we can use that to take on the rest?   Any resources are also appreciated. My table is like this:  Sitecode    Month  Amount --------    -----  ------ XX          Jan     1000 XX          Jan     3000 XX          Apr     3000 XX          Apr     1000   What I want is, to show the result something like this:  Sitecode    MonthJAN   MonthAPR --------    --------   -------- XX          4000       4000 How to find the shortest string in a list in Python Is it possible to dual boot two OS's at the same time? Example of modules that are projective but not free; torsion-free but not free Custom Tools not Saving in Toolbar on Startup/ Normal.mxt? When do you use the "this" keyword? I am studying the function and characteristic of an op-amp to build a line-following robot with the schematics below. However, in many tutorials, the way to differentiate an inverting and non-inverting op-amp is by looking at the connection to ground via the inverting or non-inverting terminal.  However, in the schematics, the op-amp is considered to have connections to ground, thus in this case, how do I differentiate it then?  I may have understood the whole concept wrongly. Pls help!    EDIT: Please ignore the switch as it may have been drawn wrongly by the supplier. Why does this formulation of Choice not follow from the Comprehension Schema? What constitutes protons? When I see pictures, I can't understand. Protons are made of quarks, but some say that they are made of 99% empty space. Also, in this illustration from Wikipedia, what's between the quarks? Why are the solutions of polynomial equations so unconstrained over the quaternions? An $n$th-degree polynomial has at most $n$ distinct zeroes in the complex numbers.  But it may have an uncountable set of zeroes in the quaternions.  For example, $x^2+1$ has two zeroes in $\mathbb C$, but in $\mathbb H$, ${\bf i}\cos x + {\bf j}\sin x$ is a distinct zero of this polynomial for every $x$ in $[0, 2\pi)$, and obviously there are many other zeroes.  What is it about $\mathbb H$ that makes its behavior in this regard to be so different from the behavior of $\mathbb R$ and $\mathbb C$?  Is it simply because $\mathbb H$ is four-dimensional rather than two-dimensional? Are there any theorems that say when a ring will behave like $\mathbb H$ and when it will behave like $\mathbb C$?   Do all polynomials behave like this in $\mathbb H$? Or is this one unusual? Why "themselves" and "himself"