Problems with ubuntu apt-get install -f  W: Some index files failed to download. They have been ignored, or old ones used instead. E: Problem executing scripts APT::Update::Post-Invoke-Success 'test -x /usr/bin/apt-show-versions || exit 0 ; apt-show-versions -i' E: Sub-process returned an error code E: Write error - write (28: No space left on device) E: IO Error saving source cache E: The package lists or status file could not be parsed or opened.   I tried mount back the tmp but it doesnts works Someone know How to fix it?  root@pipoca:/var/tmp# mount /tmp mount: can't find /tmp in /etc/fstab  root@pipoca:/var/tmp# free -m               total        used        free      shared  buff/cache   available Mem:           3008         868        1327          13         812        1964 Swap:           263           0         263  root@pipoca:/tmp# df -h Filesystem      Size  Used Avail Use% Mounted on udev            1.5G     0  1.5G   0% /dev tmpfs           301M  4.5M  297M   2% /run /dev/vda1        25G   25G     0 100% / tmpfs           1.5G  8.0K  1.5G   1% /dev/shm tmpfs           5.0M     0  5.0M   0% /run/lock tmpfs           1.5G     0  1.5G   0% /sys/fs/cgroup /dev/vda15      105M  3.6M  101M   4% /boot/efi tmpfs           301M     0  301M   0% /run/user/0        root@pipoca:/# dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge dpkg-query: no packages found matching linux-* Reading package lists... Error! E: Write error - write (28: No space left on device) E: IO Error saving source cache E: The package lists or status file could not be parsed or opened.   using   sudo apt autoremove sudo apt autoclean   I got   E: Write error - write (28: No space left on device) E: Write error - write (28: No space left on device)   using  root@pipoca:/# sudo journalctl --vacuum-time=2d Vacuuming done, freed 0B of archived journals on disk. root@pipoca:/# journalctl --vacuum-size=500M Vacuuming done, freed 0B of archived journals on disk.  root@pipoca:/# apt-get update Hit:1 http://mirrors.digitalocean.com/ubuntu xenial InRelease Hit:2 http://mirrors.digitalocean.com/ubuntu xenial-updates InRelease Hit:3 http://mirrors.digitalocean.com/ubuntu xenial-backports InRelease Hit:4 http://software.virtualmin.com/vm/6/gpl/apt virtualmin-xenial InRelease Hit:5 http://software.virtualmin.com/vm/6/gpl/apt virtualmin-universal InRelease Hit:6 http://security.ubuntu.com/ubuntu xenial-security InRelease Hit:7 https://packages.microsoft.com/ubuntu/16.04/prod xenial InRelease Hit:8 http://archive.ubuntu.com/ubuntu xenial InRelease not a reference at /usr/bin/apt-show-versions line 222. Reading package lists... Done E: Problem executing scripts APT::Update::Post-Invoke-Success 'test -x /usr/bin/apt-show-versions || exit 0 ; apt-show-versions -i' E: Sub-process returned an error code
I'm using Ubuntu 11.04 and I want to free up some space in my root directory, which is overloaded. I especially want to change the path used for installing applications (they are getting installed directly to the root drive).  Another consideration is that I'm working on a MySQL database server. The server is installed in the root directory itself, so I don't want to  risk losing any data.  Please give me some tips to help sort out this problem.
Why is the last digit of $n^5$ equal to the last digit of $n$? How do I edit my profile? This is probably a noob question, but I forgot how to edit my profile.   Can anyone help me? There is no visible button for me. 3 input XNOR gate operation Since the version of the word "that" might matter to the correct answer, I'll provide the actual title in question:  Title:  Existing Solutions that Didn't Work  If someone could explain the why of the answer, I would be appreciative.  EDIT:  It has been suggested that this is a duplicate, and that may be, in a sense.  However, the after reading the suggested prior question, I'm no closer to my answer.  I think it may have to do with my use of the word "that."  Perhaps it is incorrect?  Using these definitions of the word "that:" I'm having trouble figuring out which definition of that matches my title.  Am I even using it correctly?  Perhaps I should use which instead:  Possible Title:  Existing Solutions which Didn't Work  If my original usage is incorrect, and I should use which, then the answer is simple since which is always a pronoun or adjective, and those are both capitalized in a title.  However, I'm having difficulty understanding which part of speech that is in my original title. A "failed to fetch" error occurs when apt-get update is run. How do I fix this? Show that $g\circ f\equiv 0$ implies $\det Df\equiv 0$, where $g(x_1,...,x_n)=x_1^5+...+x_n^5$ Let $f:\mathbb{R}^n \rightarrow \mathbb{R}^n$ be a smooth function and let $g:\mathbb{R}^n \rightarrow \mathbb{R}$ be defined by $g(x_1,...,x_n)=x_1^5+...+x_n^5$. Suppose $g\circ f\equiv 0$. Show that $\det Df\equiv 0$.  I was going to start the solution from $n=2$ and then use induction on $n$.  So, for $n=2$, $f:\mathbb{R}^2 \rightarrow \mathbb{R}^2$ is a smooth function and $g:\mathbb{R}^2 \rightarrow \mathbb{R}$ where $g(x_1,x_2)=x_1^5+x_2^5$. Then $Df=\begin{pmatrix}   f_{x_1x_1} &amp; f_{x_1x_2}  \\   f_{x_2x_1} &amp; f_{x_2x_2}   \end{pmatrix}$  But now I am stuck in proving the result. Am I in the correct track? Can anyone plese give me a hint to continue?  Ok so since $g\circ f$ is $0$, the image of $f$ is the line $x_1+x_2=0$ which has no min, max or saddle.   If det$Df(x_0)&gt;0$ and $f_{x_1x_1}(x_0)&gt;0$ OR det$Df(x_0)&gt;0$ and $f_{x_1x_1}(x_0)&lt;0$, we have contradiction.   But if det$Df(x_0)&gt;0$ and $f_{x_1x_1}(x_0)=0$, then det$Df(x_0)=0$ or, det$Df(x_0)&lt;0$(Since $f_{x_1x_2}=f_{x_2x_1}$). So this is impossible.  If det$Df(x_0)&lt;0$ we have saddle and it is impossible.   So finally we conclude that det$Df(x)=0$ for all $x$. Am I correct? convert a html book to a pdf file? How can I convert a html book (consisting of a number of html files linked to each other) to a pdf file on Ubuntu?   Hope the resulting pdf file can have bookmarks according to the structures of the html book.  The html book can be downloaded from . Extract it, and go to help, and the directory manual is the html book. Why are there two different hats for "Where in the World"? I am wondering why some got a moon and others got a sun as Where in the World hat for the same action:   vs.   And is it possible two collect both e.g. from different sites? I only get moons…  I know that there has already been some spoilering . I saw this keyword for the first time and I was wondering if someone could explain to me what it does.   What is the continue keyword? How does it work? When is it used? What is the relation between electromagnetic wave and photon? How to get the center line between two linestrings Where is the track of a ship when it is shipping always in the center of the   between the coasts of Great Britain and France?   I started with 2 linestrings and I created a lot of points on the linestring with a . After that I created a distance matrix with Raster/Analysis/Proximity in QGIS. Finally I created an aspect raster from the output raster.     Is the red line really the "center line" between these two linestrings?  Is there a more efficient way to do this? There are many visa applicants who are working as an unregistered freelancer (photographer, construction contractor, fashion designer, journalist etc ). Some of these freelancers make really handsome monthly income and don't really need to work as a full time employee. Most of them receive variable amount of payments (cash, cheques, demand drafts etc) When it comes to filling a visa application form (USA, UK, Schengen etc), there is always an employment section in all visa form, eg for Schengen visa employment form :    This is a very important factor to make an application really strong.  Questions:   1 Unregistered freelancers can just simply write their profession? what documents to produce along with the application?  2 Bank statements with variable methods of payments could convince the visa officer that these are all legitimate payments? There are no book recommendations for Astrophysics here. I will write my own answer, but I am also interested in what are others' views on the question (I will NOT mark my own answer as the best one). 3D software like GeoGebra Does it exist a free interactive geometry software, like GeoGebra, which works for 3D geometry? I would be able to draw spheres, great circles, and so on. Install Alongside Windows or Something Else - Which should I use? I have old notebook with BIOS (not EFI) installed with Windows 8 RTM, want to install Ubuntu 12.10 by booting to a LiveCD.   Doing some research, I found method either to choose Something Else or Install Alongside... Which method should I use? Can I make my Ubuntu make sounds when I press Caps Lock etc.? How to search for only folders in Windows 7 instead of folders AND files I've had some issues with the new search function in Windows 7. The Search in Windows XP was packed with so many more options. The only option I can access now are Date Modified and Size.  Any pointers to how to get more options in the Windows 7 Search, or links to external programs that can make my life easier? I have two integers, x and y so that x &lt; y. How many prime numbers are there between x and y (exclusive). Is there a formula or algorithm to compute? I've recently installed Fedora 19.  is installed. But its own examples don't work. When I enter gedti the output is:  bash: gedti: command not found... Similar command is: 'gedit'   And it works correctly but when I enter powertop, the output is:  bash: powertop: command not found...   With no suggestion about the package. Why? Should I edit some configuration files or update some cache or ... ? How to ask for "Save Changes?" on Lighthing Component form when user tries to navigate away We have a Lightning Community and would like to prompt the user to "Save Changes" if they try to click one of the community's navigational components (home link, or other menu item) but they have unsaved form changes on a custom Lightning component.  Ideally, we'd have a window.confirm popup asking if they want to leave without saving their changes, and if they click Cancel, the URL navigation would be aborted.  Is this possible via custom Lighting Components and Lighting Communities, and if so, how? If not, are there any patterns to work around this?