Group in which all elements are conjugate
Infinite group with only two conjugacy classes
I wanted to try gnome-shell in 11.10 (also 12.04 now)  I removed it, however, classic Gnome is still there and the battery icon is changed (too big and can't use a icon pack on it like faenza)   Also, numerous applications were added and the entries remain on the login screen.    How can I remove it completely, rolling back all changes made when installing gnome-shell? What are the automorphisms acting on $Q\sqrt[3]{2}$ that fixes Q? Can I see which seats are available on a British Airways flight before I book? dpkg exit with error parsing file `/var/lib/dpkg/status`, what to do? Calendar month view is unresponsive on iOS 9 Network interface name changes after update to 15.10 - udev changes I updated a virtual machine running Ubuntu server 15.04 to the just released new stable 15.10.  There were no apparent problems, but after reboot the machine lost its network connection. lspci showed the correct card and lsmod proved that the driver had been loaded.  Hints about editing or removing /etc/udev/rules.d/70-persistent-net.rules did not succeed (still no network, no new file), the famous /lib/udev/write_net_rules did not even exist.  I don't have much clue regarding udev and systemd, so it took me some time to find in /sys/class/net that the network interface name changed. It became ens32, which was renamed from eth0. After I changed /etc/network/interfaces network communication was enabled again.  But - why does this happen at all? And if it happens, shouldn't the interfaces file be updated automatically?  Now that I deleted the virtual network card and created another one, eth0 becomes eno16777728, which is not so, uhm, nice.  Should this behaviour (at least that of the upgrade procedure) be reported as a bug?  Furthermore, is /etc/udev/rules.d/70-persistent-net.rules obsolete now? And (although only partly related) what about /etc/udev/rules.d/70-persistent-cd.rules?)  Edit - additional question (after accepted answer) The dependency of /etc/network/interfaces from the actual interface name bothered me. I tried a new installation of *ubuntu in another virtual machine. To my surprise, /etc/network/interfaces contained a reference to the loopback device only. However, with my original VM this change prevented the network to come up. So what else do I need to change?  Edit Well, from another test I found that a new Ubuntu Server has the network interface card in /etc/network/interfaces, while XUbuntu has not. Maybe it is using network-manager or something else. Last activity on question shows modified by user who did not ask or answer .       The  has no sign of the user sharth The  also does not have any sign of related activity   I would like to know why the user's name is associated with the question. At least why their display name shows up as having modified the question timeline activity.  Possible reason that I can think of is that, .  Is this the reason?  Is there a way (for normal users), to look for such details, other than looking at the user activity and the question's revision history. How to view all the Symbolic links,Junction points,Hard links in a Folder using dir? The command dir /a displays a list of all the files,folders in a given location. But it displays the type  for Junction Points as well as Symbolic Links to Folders. Is there any command which will differentiate and tell me which of these  are Junction Points and which are Symbolic links as well as which of the files are hard links ? how to solve $\int_{-\infty}^\infty e^{-x^2-x{\tau}} \cdot x\ dx$? Limit FTP access only to the /var/www with vsftpd I am running vsftpd as ftp server on my linux (rasbian), I log in to the machine as a root user.  I would like to be still locked to using only /var/www, how can I configure vsftpd conf to accomplish it? Why is ${x^{\frac{1}{2}}}$ the same as $\sqrt x $? Why is ${x^{\frac{1}{2}}}$ the same as $\sqrt x $?   I'm currently studying indices/exponents, and this is a law that I was told to accept without much proof or explanation, could someone explain the reasoning behind this.  Thank you. How to make sure an application keeps running on Linux I'm trying to ensure a script remains running on a development server. It collates stats and provides a web service so it's supposed to persist, yet a few times a day, it dies off for unknown reasons. When we notice we just launch it again, but it's a pain in the rear and some users don't have permission (or the knowhow) to launch it up.  The programmer in me wants to spend a few hours getting to the bottom of the problem but the busy person in me thinks there must be an easy way to detect if an app is not running, and launch it again.  I know I could cron-script ps through grep:  ps -A | grep appname   But again, that's another hour of my life wasted on doing something that must already exist... Is there not a pre-made app that I can pass an executable (optionally with arguments) and that will keep a process running indefinitely?  In case it makes any difference, it's Ubuntu. Am I being scammed by a sugar daddy? I met a guy on a sugar daddy dating site and we talked, I told him my situation and he said he would help.   He asked for my bank account information and I told him you can use cash app or PayPal to go through. He said his account manager deals with his finances. So I set up an account with a bank that I don’t use so that my primary account isn’t used.  Eventually he was in the process of sending me money and we had agreed on a amount that wasn't crazy. But then he asked for my address and I asked why and he said just wondering. Then said he wanted to send me a surprise for being his baby. Which I didn’t give.  Then later on he sent the money and said he sent me a bonus and that I was supposed to use that to pay his mothers caregiver, which he didn’t mention until after.  I kept questioning him and he was saying that he works in construction and he’s trusting me to carry out the errand. Then he said don’t let him down and I asked him if he was threatening me and he kept saying I need this done but didn’t really answer my question.  Am I being scammed? I’m about to change my password but is this a scam? Why is this command not working: "ps aux | grep xscreensaver" I didn't see any hits about this on google, so I'm asking you:  I just tried to run this command in an ssh session, local is Debian Wheezy KDE, remote is Fedora 21 Gnome:  ps aux | grep xscreensaver   and this is the output:  bash:  grep: command not found...   I never seen this before, what is the cause?  I just few hours before updated the system, but didn't see any packages marked for removal. There are only two users on the system, and only me installs or removes software on it.  EDIT #1  Here is the commands and output copied,notice that the space is not there the second time:  [root@Hostname ~]# ps aux |  grep xscreensaver bash:  : command not found... [root@Hostname ~]# ps aux | grep xscreensaver bash:  grep: command not found... Can I secretly kill every guard in a town? Is it possible to kill all of the guards in a town?  Ideally, I'd like to do this secretly so the entire town doesn't see my deeds and put a bounty on my head.  Edit: I was questing in Markarth and was told by a guard to back off and stop being nosy. I didn't and when I went to the Shrine of Talos I was set upon by a bunch of guards.  Now I have a huge bounty and I had to sneak/kill my way out of the city.  Every time I killed a group of guards the bounty was reduced by $1000, but I still have a $30,000 bounty.  I haven't even been through 1/3 of the city yet and know there has to be a lot of quests, so what do I do?  The only solution seems to kill every single guard (and inhabitant). "batch" tag turns into "batch-file" Review audit ignores closereason filter Upcasting is allowed in Java, however downcasting gives a compile error.   The compile error can be removed by adding a cast but would anyway break at the runtime.   In this case why Java allows downcasting if it cannot be executed at the runtime? Is there any practical use for this concept?   public class demo {   public static void main(String a[]) {       B b = (B) new A(); // compiles with the cast,                           // but runtime exception - java.lang.ClassCastException   } }  class A {   public void draw() {     System.out.println("1");   }    public void draw1() {     System.out.println("2");   } }  class B extends A {   public void draw() {     System.out.println("3");   }   public void draw2() {     System.out.println("4");   } } After a reinstall of Ubuntu 12.04 ,it's impossible to install commercial games, e.g Oil Rush. It gives this error:  Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/oilrush/ubuntu/dists/oneiric/main/binary-amd64/Packages  The requested URL returned error: 401 Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/oilrush/ubuntu/dists/oneiric/main/binary-i386/Packages  The requested URL returned error: 401 Some index files failed to download. They have been ignored, or old ones used instead.   I bought these games in 11.10, but I installed these games in 12.04 before... How can I solve this problem? Why do certain sites require more reputation for privileges? So, let's take Skeptics.SE for an example. You can become a trusted user when you acquire 4000 rep., not 20000  I was like, wow, so is it like this because of the lack of users on Skeptics.Se, as in, not so much as Stack Overflow or something?  Why do some sites need less reputation to be a trusted user?