$ sudo du -h -d 0 home/ 309G    home/  $ df -h Filesystem      Size  Used Avail Use% Mounted on ... /dev/sda4       550G  309G  214G  60% /home ...   System Monitor on Ubuntu shows the used space on /home  is 331.1 GB    Do the different ways measure the same thing?   How differently do they make the measurements?  Thanks.
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?
I was presented with the following problem:      Prove that there exist solutions to $x^2+y^2=z^n$ for all $n$, with $x,y,z, n \in \mathbb{N}$   I showed that by taking any Pythagorean triple $x^2+y^2=z^2$ and multiplying by $z^{2(n-1)}$ we get $(z^{n-1}x)^2+(z^{n-1}y)^2=(z^2)^n$, which allows me to generate solutions easily for any value of $n$. I managed to find several similar questions on this site, such as  concerning the specific case $n=3$. I notice that all of these questions take a similar approach and start with a Pythagorean triple and use it to generate general solutions.  Is there a way to prove the statement (or better yet provide solutions to the equation) without first relying on Pythagoras? Temperature in space Temperature is a measure of kinetic energy transferred to particles, henceforth,  being vacuum, temperature cannot be measured. But then, there is cosmic background radiation. It is the leftover heat from the Big Bang, but then heat in space doesn't make sense, how does this radiation, heat up space time when it technically cannot be heated up? Moreover why is it referred to as heat when it is approximately just $2.5$ Kelvin, which is just above absolute zero? Making voltmeter accepting bipolar input voltage, using a microcontroller I want to build a very simple voltmeter using ATMEGA328 ADC. I can successfully measure up to 20v (using a voltage divider), but the problem is, I don't understand how to measure the voltage properly, if negative and positive terminals are switched.   Only way I could think of is adding another ADC input which is responsible for measuring the 'inverted voltage'. The join both ADC inputs, but add diodes in between, so one channel works with (+-) and the other channel works with (-+) and then 'merge' the input from both channels using code. Then I should be able to measure things like sin wave for example (where polarities switch).   Is the concept correct or is there a better way to do this? Thanks! Override route helper methods How to find the period of the sum of two trigonometric functions How to make an embedded question from "What time is it?" I'm new to Ubuntu. What's the application extension for development reasons? I know Windows is mainly .exe and Mac is .dmg or .app. Does Linux have an unique one? Can a Muggle inadvertently create a horcrux-like object? I think that we have it well-established (regardless of whether or not one sees this as flawed logic) that Harry is not a Horcrux.  A Horcrux has to be made intentionally, and the recipient is cursed and classified as an "evil object," etc.  Neither of which is true for Harry - so, as stated by JKR herself, Harry is not a Horcrux as such.  But the fact remains that murder can, in fact, accidentally create something that shares a key property of the Horcrux: the soul splits, attaches itself to the nearest recipient, and lingers inside.  As it does in Harry's case.  So my question is: is this only true for wizards?  A Muggle cannot utilize a spell to create a Horcrux.  But, if a Horcrux-like object / being can be created accidentally through murder without intentional Horcrux-creating spells, can this also happen in the case of a Muggle committing murder?    Can a Muggle commit murder, have their soul split, and have the piece of the soul inadvertently attach itself to something nearby without any Horcrux-creating spell being cast? Unable to mount Windows (NTFS) filesystem due to hibernation Whenever I boot Ubuntu, I get a message that it cannot mount my windows partition, and I can choose to either wait, skip or manually mount.  When I try to enter my Windows partition through Nautilus I get a message saying that this partition is hibernated and that I need to enter the file system and properly close it, something I have done with no problem so I don't know why this happens.    Here's my partition table, if any more data is needed please let me know.     Device Boot      Start         End      Blocks   Id  System /dev/sda1            2048    20000767     9999360   83  Linux /dev/sda2        20002814   478001151   228999169    5  Extended /dev/sda3   *   478001152   622532607    72265728    7  HPFS/NTFS/exFAT /dev/sda4       622532608   625141759     1304576   82  Linux swap / Solaris /dev/sda5        20002816   478001151   228999168   83  Linux To be honest I find it hard to keep up with all the changes, and very frequently I have to go look at the privileges list to see whether a user (that I'm looking at, so I have his reputation value) has a certain privilege or not.  However, I still don't know what that user will actually see or how the site actually behaves for that user.  There's quite a number of posts here on meta about "where did this go" and "why can't I" and I can't really tell either way how a site behaves for a user with a reputation level of 2500.  So, I propose the following functionality:   For all users, be able to view the site as though you had less reputation than you actually have Bonus-feature: For all users, be able to use the site at that reputation level, unless some features of low-level users conflict with your actual functionality For mods, be able to view the site as a specific users (be able to see all he sees, exactly the way he sees it), but of course not pose as that user (ie. things I do would still be me)   The UI could be merged into the mod menu and the privileges menu:    (Note, I chose a user randomly, Olivier Pons is in no way related to this question or flags, or whatever that I know of.) How to find out why "context is incorrect"? How does langid field in biblatex differ from language field? Could someone summarise the differences in the use of the langid field from language field in biblatex? Documentation to Gost package for bibtex says that langid is a synonym of language but has priority over it. I have continuous problems of network dropping connections on wifi with ubuntu 16.04, I have an ASUS R510J, this is my network card:  ##### lspci #############################  03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8821AE 802.11ac PCIe Wireless Network Adapter [10ec:8821]         Subsystem: AzureWave RTL8821AE 802.11ac PCIe Wireless Network Adapter [1a3b:2161]         Kernel driver in use: rtl8821ae  04:00.1 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 12)         Subsystem: ASUSTeK Computer Inc. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [1043:200f]         Kernel driver in use: r8169   sudo service network-manager restart doesnt's help, as I never regain internet connection after it drops, and I have to restart the PC. On Ethernet cable I have no problem.  What do you think is the issue? drivers?  thank you I just noticed a weird thing in my reputation tab on StackOverflow.    That last question mentioned (but not linked, had to find it via search):   I must have amnesia as I have no memory of ever interacting with this post. I don't even know what xampp and pdftk are so I don't know why I would even be interested in such a question. 2 reputation points more or less is not a big deal, but the fact I got rep change from question I've never seen before is odd and I'm wondering what happened. for loop wget directory creation error As a Ubuntu beginner. I am trying to download links from multiple text files with wget2 in batch. The -P &quot;$f&quot; creates directory name with .txt suffix. Is it possible to ignore .txt for -P &quot;$f&quot;. Any modification suggestions. for f in *.txt;do wget2 -i &quot;$f&quot; -P &quot;$f&quot;;done What is the value of lim$_{n\to \infty} a_n$ if $\lim_{n \to \infty}\left|a_n+ 3\left(\frac{n-2}{n}\right)^n \right|^{\frac{1}{n}}=\frac{3}{5}$? Let $\{a_n\}$ be a sequence of real numbers such that $$\lim_{n \to \infty}\left|a_n+ 3\left(\frac{n-2}{n}\right)^n \right|^{\frac{1}{n}}=\frac{3}{5}.$$  What is the value of $\lim_{n\to \infty} a_n$? I know it might be too easy for you guys here. I'm practicing some problems in the textbook, but this one really drove me crazy. From $\gcd( a, b ) = 1$, I have $ax + by = 1$, where should I go from here? The extra $ac$ is so annoying. Any hint?    Thanks, Chan Can someone point me to a proof that the set of irrational numbers is uncountable? I know how to show that the set $\mathbb{Q}$ of rational numbers is countable, but how would you show that the irrationals are uncountable? Best practices for making a WordPress site "movable"? I'm planning to buy a domain and install a WordPress site on it at a web-hosting company.  But first I'll need to iron-out some bugs...  I got a working LAMP-stack at my home-computer, so I'm thinking about first installing my site locally - off the Internet.  I'll be mostly tweaking and making "test-posts" to check that everything works, but I'll probably also make some posts I'd like to keep when I move the site and take it online.  When I'm done chasing bugs; I guess I'll just package the public_html|www directory-tree and upload it to the web-hosting company, and also export the database from my home-computer to the web-hosting.    What I'm wondering if there are some "best practices", some do-s and don't-s, some major pits to take note of?    For example, how can ensure the smooth transition of domain-name in posts and links as such, from localhost to whatever-i-end-up-buying.com (I know from previous attempt of running WordPress at my home computer, that this didn't always work quite well...). Total time derivatives and partial coordinate derivatives in classical mechanics