So df is telling me that I'm using 49/59G, so I set out to find my space.  $ df -h  Filesystem      Size  Used Avail Use% Mounted on /dev/vda1        59G   49G  7.9G  86% / none            4.0K     0  4.0K   0% /sys/fs/cgroup udev            2.0G  4.0K  2.0G   1% /dev tmpfs           396M  340K  396M   1% /run none            5.0M     0  5.0M   0% /run/lock none            2.0G     0  2.0G   0% /run/shm none            100M     0  100M   0% /run/user overflow        1.0M     0  1.0M   0% /tmp   ``` I first tried du  5.1G    . 2.3G    ./var 1.3G    ./usr 973M    ./var/log 834M    ./lib 736M    ./lib/modules 713M    ./var/lib 600M    ./root 592M    ./var/log/nginx 456M    ./var/www   Now, I'm no math major, but I'm pretty sure that's not 49G.  I tried ncdu, and that's telling i'm using 5GB / 128GB
When I sum up the sizes of my files, I get one figure. If I run du, I get another figure. If I run du on all the files on my partition, it doesn't match what df claims is used. Why are there so many different figures for the total size of my files? Can't computers add?  Speaking of adding: when I add the “Used” and “Available” columns of df, I don't get the total figure. And that total figure is smaller than the size of my partition. And if I add up my partition sizes I don't get my disk size! What gives?
Why did Voldemort take the wand of one of his most loyal servants? In Harry Potter and the Deathly Hallows, chapter one The Dark Lord Ascending, Voldemort believes he must use a wand other than his own in order to kill Harry, when Harry is moved from Privet Drive. He demands Lucius Malfoy's wand, and gets it.   My question is, why did Voldemort take the wand of one of his most loyal servants, rendering Lucius Malfoy useless if a battle was to occur?  If I remember correctly, he had Ollivander at his disposal, and he was the one who told him to use another wand in first place. Why not ask Ollivander to create another wand, or just use ones that he had ready to sell in his shop at Diagon Alley? He could even have taken Ollivander's own wand. If my memories are correct, a wand's importance was compared to that of a limb. I am using Selenium 2/WebDriver for automation. I have a table and am trying to select a row in it. 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Proving that a number with digits 1...9 in some order, ending in 5, is not a perfect square. If "x" is a 9 digit number , which contains digits from 1 to 9 which ends in 5 . Prove that it can't be a perfect square ( digits are not to be repeated).  Please suggest the solution of this question. Suspended user cannot award bounty Can I use Gödel numbers to make a proof? How can I make sure that my on-screen colors are consistent? Unique constraint that allows empty values in MySQL Change date and time format from csv file without using date -d I have a .csv file contains   Data1|Data2|10/24/2017 8:10:00 AM   I want to change date and time format of column 3 as following:  From 10/24/2017 8:10:00 AM (12-Hour) to 20171024 08:10:00(24-hour).  Not using -d A short story about finding an inhabitable planet and meeting aliens I want to write several classes, most of them will use KOMA classes as base class.  However I stumbled upon the problem that some options (mainly concerned with layout) are not processed if given in the wrapper class:    \begin{filecontents}{test.cls}     \ProvidesClass{test}[2015/01/01]     \DeclareOption*{\PassOptionsToClass{\CurrentOption}{scrartcl}}     \ProcessOptions\relax     \LoadClass[paper=a5]{scrartcl}   \end{filecontents}  \documentclass{test}  \usepackage{blindtext}  \begin{document}   \section{Test}   \blindtext \end{document}   This results in   LaTeX Warning: Unused global option(s):     [paper=a5]  If i give the option as \documentclass[paper=a5]{test} it is used correctly, because I pass the options to scrartcl. However I want to change the defaults for the layout.   How can I achieve this? BibTeX loses capitals when creating .bbl file Titles of articles I'm about to cite contain upper case letters and when using BibTeX it converts them to lower case ones. This happens only in the title and only the first letter conserves its case. For example, when I cite an article about HF, the reader won't know if it is about Hafnium (Hf) or fluorine acid (HF).  I know that I can fix it manually in the .bbl file but I would like to avoid it, or fix it automatically. After installing Adobe PDF reader, it opens files with the .PDF file extension. Ones' default web browser opens .html files and notepad opens .txt files, etc.  Where exactly in the registry are these filetype - program associations stored in the registry?   In other words, how does Windows know with which software/program it must open a certain file(type)? Removing empty lines in Notepad++ How can I model flips until N successes? You and I decide to play a game where we take turns flipping a coin. The first player to flip 10 heads in total wins the game. Naturally, there is an argument about who should go first.  Simulations of this game show that the player to flips first wins 6% more than the player who flips second (the first player wins approx 53% of the time).  I'm interested in modelling this analytically.  This isn't a binomial random variable, as there are no fixed number of trials (flip until someone gets 10 heads). How can I model this?  Is it the negative binomial distribution?    So as to be able to recreate my results, here is my python code:  import numpy as np from numba import jit   @jit def sim(N):      P1_wins = 0     P2_wins = 0      for i in range(N):          P1_heads = 0         P2_heads = 0         while True:              P1_heads += np.random.randint(0,2)              if P1_heads == 10:                 P1_wins+=1                 break              P2_heads+= np.random.randint(0,2)             if P2_heads==10:                 P2_wins+=1                 break     return P1_wins/N, P2_wins/N   a,b = sim(1000000) A few months ago I set full disk encryption during installation of Ubuntu 17.10. Now, I've decided to upgrade. The upgrade ran to the end without any problems. However, after reboot I am not able to log into my encrypted disk.  Where can be the problem? I am 100% sure I press the "right keys" on the keyboard, but technically I don't know what I am writing because of "*" characters and maybe after upgrade my keyboard layout changed. I use some characters which might be somewhere else on the keyboard. What language is default after upgrade?   By the way, I've already tried Caps-lock, but still no luck.  Help will be really appreciated. I am not a fan of installing my system and all backups over and over again. When should we consider a dataset as imbalanced? I'm facing a situation where the numbers of positive and negative examples in a dataset are imbalanced.  My question is, are there any rules of thumb that tell us when we should subsample the large category in order to force some kind of balancing in the dataset.  Examples:   If the number of positive examples is 1,000 and the number of negative examples is 10,000, should I go for training my classifier on the full dataset or I should subsample the negative examples? The same question for 1,000 positive example and 100,000 negative. The same question for 10,000 positive and 1,000 negative. etc... I'm using a  freely downloadable latex class file and the style is set to \bibliographystyle{ieeetr}. But when I cite something with \cite{} I get it inside ().   For example I get it as abc et al. (1) but what I want to get is abc et al. [1].   Please tell me how to get my citations inside [ ] ? Solve $x^2+2=y^3$ using infinite descent? Bluetooth indicator disappears on turning off bluetooth Everytime I turn off my bluetooth, the indicator icon in the system tray disappears, as opposed to just greying out as expected. Next time I need to go to the settings select bluetooth to turn it on, which makes the indicator to reappear.  Is there anyway I can make the indicator icon not disappear but stay greyed out when not in use? Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc