I have heard, that  will have  enabled by default. How will this be done? By adding a discards option to the  mount options or by running a cron-job?   Will the default options for Trim be automatically compatible with the  and encryption layers of the standard Ubuntu-system encryption?  It would be great to see some details about this.
I know that the Linux kernel supports TRIM as of version 2.6.33, so there should be TRIM support in ubuntu.  Is TRIM enabled by default or do I need to change some settings or install additional software for it to work? If so, how?
What is the difference between local and .local in ubuntu? Echoing path in ubuntu returns following colon separated paths,  /home/stack/bin:/home/stack/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin   In these paths at some places there is local while at others .local is used what is the difference between both? Can the system leave a deletion reason when it deletes a question? they were question banned; it turned out it (in part) it was because of deleted questions.   was deleted by the Community user.  I'm aware it will delete old posts that have a negative score, but for a minute or two, I was really puzzled as to why it was unilaterally deleted without some notation left.  Can we have the Community user leave a notation in a post's history as to why the post was deleted?    Something like the following would suffice:     Post deleted automatically due to having negative votes and no activity for three months What exactly did mv /tmp/folder/* /* do to my filesystem? It's hard to search for special characters on google, which is why I'm posting this here.  I recently ran (as root) a mv /tmp/folder/* /* when I meant to run mv /tmp/folder/* ./ Big mistake!  Things broke! A lot of files got mixed up and placed into strange places, none of the normal unix commands worked (ls, dir, cat, etc) and once you logged off, you couldn't ssh back in -- it would give you a prompt, but not accept the old passwords.  Running ls /* shows me that it performs ls on every directory in /. If I tried to draw a parallel, then mv should have simply moved (or copied?) the files to every directory in /. Instead, really weird things happened, and I was just curious what exactly was going on.  More info: The files in /tmp/folder had been transferred from a windows machine, and had been named file (#).txt, where (#) is a number up to two digits, with a space between file and the parenthesis. There were ~40 of these text files. Negative energy levels in the diagram for a hydrogen atom The higher the number of the shell (n), the higher is the energy level of the electron. However, why was it necessary to have negative values. So for example, when $n=1$, the energy could be $5 eV$ and for $n=2$, $6 eV$... having positive values could also have supported the idea that as $n$ increases, energy of electron increases. What is the point of having negative numbers, does it somehow aid calculations? Can't install Oracle JDK 9 I uninstalled jdk packages and now can't install them back. I managed to install oracle-java7-installer and oracle-java8-installer but can't install oracle-java9-installer. It seems that my computer tries to download wrong version of oracle-java9-installer 177 when version i would be able to download is 178.    $ wget http://download.java.net/java/jdk9/archive/178/binaries/jdk-9+178_linux-x64_bin.tar.gz --2017-07-21 11:00:02--  http://download.java.net/java/jdk9/archive/178/binaries/jdk-9+178_linux-x64_bin.tar.gz Connecting to 10.144.1.10:8080... connected. Proxy request sent, awaiting response... 200 OK Length: 293348142 (280M) [application/x-gzip] Saving to: 'jdk-9+178_linux-x64_bin.tar.gz'  jdk-9+178_linux-x64_bin.tar.gz     1%[&gt;                                                          ]   5.42M  5.04MB/s               ^C  $ wget http://download.java.net/java/jdk9/archive/177/binaries/jdk-9+177_linux-x64_bin.tar.gz --2017-07-21 11:00:16--  http://download.java.net/java/jdk9/archive/177/binaries/jdk-9+177_linux-x64_bin.tar.gz Connecting to 10.144.1.10:8080... connected. Proxy request sent, awaiting response... 404 Not Found 2017-07-21 11:00:17 ERROR 404: Not Found.   Can you help? apt-get tries to install Oracle JDK 9.  I run Ubuntu 16.04 in virtual machine hosted by win7  Full error message:  sudo apt-get install oracle-java9-installer Reading package lists... Done Building dependency tree        Reading state information... Done oracle-java9-installer is already the newest version (9b177-1~webupd8~0). 0 upgraded, 0 newly installed, 0 to remove and 147 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Do you want to continue? [Y/n] Y Setting up oracle-java9-installer (9b177-1~webupd8~0) ... Using wget settings from /var/cache/oracle-jdk9-installer/wgetrc Downloading Oracle Java 9... --2017-07-21 10:54:11--  http://download.java.net/java/jdk9/archive/177/binaries/jdk-9+177_linux-x64_bin.tar.gz Connecting to 10.144.1.10:8080... connected. Proxy request sent, awaiting response... 404 Not Found 2017-07-21 10:54:13 ERROR 404: Not Found.  download failed Oracle JDK 9 is NOT installed. dpkg: error processing package oracle-java9-installer (--configure):  subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing:  oracle-java9-installerE: Sub-process /usr/bin/dpkg returned an error code (1) How can I install Ubuntu without CD and USB? I want to install Ubuntu on my laptop that doesn't have a CD-ROM drive and I have no spare USB disk. I've tried Wubi, but that doesn't seem to work (since it prompts me to have the CD in the drive, which I don't have).  How can I install Ubuntu, easily and in a fast way?  P.s: I want to dual boot it with Windows 7 (which was preinstalled).  Edit:   When extracting the ISO to a folder and running Wubi it does install, but when I reboot the computer, it doesn't show GRUB, nor can I choose if I want to boot Ubuntu or Windows 7. After trying for the third time today, wubi gives me an error: Permission denied   I'm the administrator on the PC. If I calculate the median of a sufficiently large number of observations drawn from the same distribution, does the central limit theorem state that the distribution of medians will approximate a normal distribution? My understanding is that this is true with the means of a large number of samples, but is it also true with medians?  If not, what is the underlying distribution of sample medians? Is there a way to merge to two bars in GNOME 3? Best case scenario would be to have one single bottom or top bar that has all the symbols on the left side and the rest like the time indicator, connections, on/off button, etc. on the right side.  Is that possible in any way? How to check battery temperature? How do I know the normal temperature of it?  My OS is Ubuntu, and my laptop is Lenovo G470.  Output of acpi -t:  Thermal 0: ok, 0.0 degrees C I find it curious that the most obvious way to create Date objects in Java has been deprecated and appears to have been "substituted" with a not so obvious to use lenient calendar.  How do you check that a date, given as a combination of day, month, and year, is a valid date?  For instance, 2008-02-31 (as in yyyy-mm-dd) would be an invalid date. Counting set for generating functions Give  a  proof  of  the  following  identity  by  counting  two  sets  of  partitions  in  two  different ways.  \begin{equation*}  \prod_{i\geq 0}(1+x^{2i+1})=1 + \sum_{n\geq 1}x^{n^2}\prod_{j=1}^n\frac{1}{1-x^{2j}}  \end{equation*} To prove this inductively, i only successfully complete the base cases, however the counting set for the left side i concluded that would be the number of partitions of n with distinct odd parts and for RS the product part would be the number of partitions of n with even parts, how would the summation of $x^{n^2}$ come into play with counting set. How would i initiate my proof? How do I read a text file with variable hexadecimal value columns in matlab? If the universe is 3D, how is space-time like a "fabric"? Why is it so difficult to pull an immersed mug out of the water? Suppose I put a mug in the water and then tilt it so that the water gets inside. It then floats due to buoyant force. But if I try to pull it out then a lot of force is needed. That's due to suction? What exactly happens at the moment when the force I apply is enough to pull the mug out? And what causes the loud pop sound when that happens? I'm currently taking Quantum Mechanics in school and I came across a table displaying the following in the given order:   $E_n (\text{energy levels}), g_n (\text{eigen functions})$   $n \ l, [m]$  $E_1, 1$   $1s, [0]$  $E_2, 4$   $2s, [0]$ $2p, [-1,0,1]$  $E_3, 9$   $3s, [0]$ $3p, [-1,0,1]$ $3d, [-2,-1,0,1,2]$    Now, as I understand $n$ defines the size of the orbital, $l$ the shape and $m$ the orientation.  My question is, how does the atoms shell model fit into this if one can have two electrons per orbital? Are $1s$ the same as the orbital $2s$, but just renamed for the sake of higher energy levels? Or do two similarly looking orbits exist for different energy levels? For example two "layers" of spherical electron clouds for an atom with $4$ electrons.  I just can't see how $2$, $8$, $18$ becomes $2$, $8$, $8$ as we were taught in Physics at high school? Am I missing something? I am attempting to settle a friendly bet.  Would a pendulum swing indefinitely in a hypothetical vacuum (i.e. no air resistance) having a hypothetical frictionless bearing (i.e. no energy lost due to friction) assuming the following   The frictionless vacuum is on Earth (9.8 m/s^2). The pendulum is already in motion and no other external forces other than gravity act on the pendulum. From      Every linear function on a finite-dimensional space is continuous.   I was wondering what the domain and codomain of such linear function are?   Are they any two topological vector spaces (not necessarily the same), as along as the domain is finite-dimensional? Can the codomain be a different normed space (and may not be finite-dimensional)?  I asked this because I saw elsewhere the same statement except the domain is a finite-dimensional normed space, and am also not sure if the codomain can be a different normed space (and may not be finite-dimensional).  Thanks and regards! Self-Contained Proof that $\sum\limits_{n=1}^{\infty} \frac1{n^p}$ Converges for $p > 1$ I get      every few minutes on Kubuntu (KDE), and the panels disappear.  It restarts itself automatically, so it's not a real problem, just an annoyance, but it is a big annoyance.  I've tried sudo apt install --reinstall plasmashell plasma-desktop, but that made no difference.  When I try a backtrace from the error message, it says it's unable to produce a useful backtrace. Answer didn't load temporary