I am running Ubuntu Server 14.04 LTS on a desktop at my home that I was intending to turn into a server, but I never really did much on it. I then decided to turn it into a send-only SMPT server, but when I tried sudo apt-get install postfix to install postfix, I got this error:  You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies:  linux-image-extra-3.19.0-42-generic : Depends: linux-image-3.19.0-42-generic but it is not going to be installed  linux-image-extra-3.19.0-56-generic : Depends: linux-image-3.19.0-56-generic but it is not going to be installed  linux-image-generic-lts-vivid : Depends: linux-image-3.19.0-56-generic but it is not going to be installed                              Recommends: thermald but it is not going to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).   I tried running sudo apt-get -f install, but that didn't work:  Preparing to unpack .../linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb ... Done. Unpacking linux-image-3.19.0-56-generic (3.19.0-56.62~14.04.1) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.19.0-56-generic' to '/boot/vmlinuz-3.19.0-56-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error                                                                           dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.19.0-56-generic /boot/vmlinuz-3.19.0-56-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.19.0-56-generic /boot/vmlinuz-3.19.0-56-generic Preparing to unpack .../linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb ... Done. Unpacking linux-image-3.19.0-42-generic (3.19.0-42.48~14.04.1) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.19.0-42-generic' to '/boot/vmlinuz-3.19.0-42-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error                                                                           dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.19.0-42-generic /boot/vmlinuz-3.19.0-42-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.19.0-42-generic /boot/vmlinuz-3.19.0-42-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-3.19.0-56-generic_3.19.0-56.62~14.04.1_amd64.deb  /var/cache/apt/archives/linux-image-3.19.0-42-generic_3.19.0-42.48~14.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   I tried installing other packages and the error persists across all uses of apt-get install.  I also followed the instructions at  to run sudo apt-get clean, but that still didn't solve my problem.  So what is wrong? What must I do to get apt-get working again?  I do not know much about this issue, so I may not have provided all the necessary information. Please comment if I need to add more.
Currently there is not enough space on by /boot partition/folder and the sofware update can not be performed.   Question: how should I correctly free-up some space in that directory?  Here is the listing:  root@mindaugas-ubuntu-14:/boot# ls -la total 156607 drwxr-xr-x  4 root root     3072 Kov 12 09:37 . drwxr-xr-x 24 root root     4096 Kov 23 23:36 .. -rw-r--r--  1 root root  1163858 Rgs  4  2014 abi-3.13.0-36-generic -rw-r--r--  1 root root  1164720 Grd 16 03:17 abi-3.13.0-44-generic -rw-r--r--  1 root root  1164967 Sau 13 22:12 abi-3.13.0-45-generic -rw-r--r--  1 root root  1164852 Kov 10 22:43 abi-3.13.0-46-generic -rw-r--r--  1 root root   165671 Rgs  4  2014 config-3.13.0-36-generic -rw-r--r--  1 root root   165748 Grd 16 03:17 config-3.13.0-44-generic -rw-r--r--  1 root root   165748 Sau 13 22:12 config-3.13.0-45-generic -rw-r--r--  1 root root   165748 Kov 10 22:43 config-3.13.0-46-generic drwxr-xr-x  5 root root     1024 Kov 12 09:37 grub -rw-r--r--  1 root root 29225220 Rgs 25  2014 initrd.img-3.13.0-36-generic -rw-r--r--  1 root root 29264463 Sau 24 20:22 initrd.img-3.13.0-44-generic -rw-r--r--  1 root root 29267419 Vas 23 20:30 initrd.img-3.13.0-45-generic -rw-r--r--  1 root root 29268175 Kov 12 09:37 initrd.img-3.13.0-46-generic drwx------  2 root root    12288 Rgs 14  2014 lost+found -rw-r--r--  1 root root   176500 Kov 12  2014 memtest86+.bin -rw-r--r--  1 root root   178176 Kov 12  2014 memtest86+.elf -rw-r--r--  1 root root   178680 Kov 12  2014 memtest86+_multiboot.bin -rw-------  1 root root  3386479 Rgs  4  2014 System.map-3.13.0-36-generic -rw-------  1 root root  3388834 Grd 16 03:17 System.map-3.13.0-44-generic -rw-------  1 root root  3389258 Sau 13 22:12 System.map-3.13.0-45-generic -rw-------  1 root root  3389458 Kov 10 22:43 System.map-3.13.0-46-generic -rw-------  1 root root  5806848 Rgs  4  2014 vmlinuz-3.13.0-36-generic -rw-------  1 root root  5814496 Grd 16 03:17 vmlinuz-3.13.0-44-generic -rw-------  1 root root  5814112 Sau 13 22:12 vmlinuz-3.13.0-45-generic -rw-------  1 root root  5814592 Kov 10 22:43 vmlinuz-3.13.0-46-generic   There was a mention of it here:      $ sudo apt-get remove linux-image-2.6.31-21-generic   but will it delete all the files?
Separate long math text under sum symbol into different lines? I have the following equation, where there is a lot of stuff under the sum symbol:  \begin{equation} d(\vec{x},\vec{y})=   \sum_{Z_{xy}\in\vec{Z}_{xy},\forall x\in\vec{x},\forall y\in\vec{y}}      f(Z_{xy}) \end{equation}   In the resulting document, I find it kind of hard to read. Is there a way to write the equation to make the result more readable, e.g. putting the stuff under the sum symbol on different lines? Origin of the Mustache Twirling Villain Whenever someone thinks about silent cinema the image of the laughing villain, twirling his mustache, and tying the hapless blonde beauty to the railroad, pops up in our collective memory. But in which movie (or movies) did that particular image first appear? iOS: Your passcode is required to enable Touch ID Occasionally, when unlocking my iPhone or iPad, I get the following message:     Your passcode is required to enable Touch ID   Now this is not after a number of failed attempts or turning the device off. The device was used within the last 12 hours. Two of the devices are less than 2 months old, and one is a year old. Everything is up to date. It appears to be happening more-or-less at random.  Does anybody know why this message might appear? What's the name of the move where the player swaps King and Rook/Castle in Chess? Why is this move important? I'm a chess beginner, and I was wondering: why was this movement introduced to chess, and why is it important to the game? I am planning on doing a fresh install of Ubuntu and want to know what is the correct way to install ATI Catalyst Video Driver?      There are multiple valid answers for this question spanning over several versions of Ubuntu. For your convenience an index of each below: Why can't light escape from a classical black hole? How to run test methods in specific order in JUnit4? Explicit solution for linear regression with two predictors I have some samples of data of the form $x,y$ and $z=f(x,y)$. I wish to fit a plane $$z = Ax + By + C$$ to the data with the smallest mean square errors.  I have found an "answer" in section 3 of  document, but it is left in the form of some equations left to be solved. I just about have the ability to solve these equations, but the process gets so messy that the likelihood of me making a mistake is quite high. Surely someone has written out the full solution longhand somewhere (it might be called "closed form") anyway, in the form $$A=\ldots,$$ $$B=\ldots,$$ $$C=\ldots.$$  EDIT: Maybe "closed form" is the wrong phrase. So let me be clear. I want an explicit solution for $A$, $B$, and $C$, and not a solution that ends with "So now if you can solve these equations then you can discover the values of $A$, $B$ and $C$". mysql select distinct rows into a comma delimited list column I have been working on this exercise for a while now. It's in B.L. van der Waerden's Algebra (Volume I), page $19$. The exercise is as follows:     The order of the symmetric group $S_n$ is $n!=\prod_{1}^{n}\nu$. (Mathematical induction on $n$.)   I don't comprehend how we can logically use induction here. It seems that the first step would be proving $S_1$ has $1!=1$ elements. This is simply justified: There is only one permutation of $1$, the permutation of $1$ to itself.  The next step would be assuming that $S_n$ has order $n!$. Now here is where I get stuck. How do I use this to show that $S_{n+1}$ has order $(n+1)!$?  Here is my attempt: I am thinking this is because all $n!$ permutations of $S_n$ now have a new element to permutate. For example, if we take one single permutation $$ p(1,\dots,n) = \begin{pmatrix} 1 &amp; 2 &amp; 3 &amp; \dots &amp; n\\ 1 &amp; 2 &amp; 3 &amp; \dots &amp; n \end{pmatrix} $$ We now have $n$ modifications of this single permutation by adding the symbol $(n+1)$:  \begin{align} p(1,2,\dots,n,(n+1))&amp;= \begin{pmatrix} 1 &amp; 2 &amp; \dots &amp; n &amp; (n+1)\\ 1 &amp; 2 &amp; \dots &amp; n &amp; (n+1) \end{pmatrix}\\ p(2,1,\dots,n,(n+1))&amp;= \begin{pmatrix} 1 &amp; 2 &amp; \dots &amp; n &amp; (n+1)\\ 2 &amp; 1 &amp; \dots &amp; n &amp; (n+1) \end{pmatrix}\\ \vdots\\ p(n,2,\dots,1,(n+1))&amp;= \begin{pmatrix} 1 &amp; 2 &amp; \dots &amp; n &amp; (n+1)\\ n &amp; 2 &amp; \dots &amp; 1 &amp; (n+1) \end{pmatrix}\\ p((n+1),2,\dots,n,1)&amp;= \begin{pmatrix} 1 &amp; 2 &amp; \dots &amp; n &amp; (n+1)\\ (n+1) &amp; 2 &amp; \dots &amp; n &amp; 1 \end{pmatrix} \end{align}  There are actually $(n+1)$ permutations of that specific form, but we take $p(1,\dots,n)=p(1,\dots,n,(n+1))$ in order to illustrate and prove our original statement. We can make this general equality for all $n!$ permutations: $p(x_1,x_2,\dots,x_n)=p(x_1,x_2,\dots,x_n,x_{n+1})$ where $x_i$ is any symbol of our finite set of $n$ symbols and $x_{n+1}$ is strictly defined as the symbol $(n+1)$.  We can repeat this process for all $n!$ permutations in $S_n$. This gives us $n!n$ permutations. Then, adding in the original $n!$ permutations, we have $n!n+n!=(n+1)n!=(n+1)!$. Consequently, $S_n$ has order $n!$.  How is my reasoning here? Furthermore, is there a more elegant argument? I do not really see my argument here as incorrect, it just seems to lack elegance. My reasoning may well be very incorrect, however. If so, please point it out to me. My dev team is getting ready to start a new project. The shop has been a "VB shop" since the days of VB3, but the prevailing opinion now is that we're a ".NET shop" and since C# was created specifically for .NET, whereas VB.NET was a retrofit, we've decided to move forward writing C# only. The controversy revolves around the question of whether the Microsoft.VisualBasic namespace has a legitimate place in new development or if it is only for backward compatibility for VB6 (and older) code. A further, and more interesting question is whether the code "under" the Microsoft.VisualBasic namespace is even .NET code of if it is really the old VB runtime carefully packaged in a .NET wrapper, making it in fact a COM interop control (similar to how WinForms wraps the non-.NET Win32 windowing API but exposes only .NET APIs for consumption).  To make this even more confusing, our dev team has a Microsoft Consulting Services consultant telling us Microsoft no longer supports Visual Basic, including the VB runtime underlying the Microsoft.VisualBasic namespace.  What I'm looking for are links -- preferably to unimpeachable Microsoft sources -- to documentation that definitively answers this question one way or the other. I've already tried several search permutations on Google and not gotten any closer to getting to the bottom of this question.  EDIT: Apparently I didn't make my question clear. I'm not asking if VB.NET is true .NET code. I'm trying to determine if whatever is "under" the Microsoft.VisualBasic namespace is .NET code or if it's the old VB6 runtime carefully packaged and exposed as .NET code. Someone already said that 9/10 of the namespace simply wraps code from elsewhere in .NET; what about that other 1/10? I can't seem to work out the inequality $(\sum |x_n|^q)^{1/q} \leq (\sum |x_n|^p)^{1/p}$ for $p \leq q$ (which I'm assuming is the way to go about it). Another part of my daily  on SE sites.  When viewing a question and it's time to move on, I'll often simply click one of the tags in the question to bring me back to a list of questions with that tag.  This doesn't work in the Android app.  Obligitory screenshot.  I tried to draw a finger that looked like it was tapping a tag, but it ended up looking like, well...  something else, let's say. When should one use "should" and when should one use "must"? I tend to use should when it's a suggestion I don't have a strong opinion on, i.e. it could be done in many other ways than the one I'm suggesting and it can still happen.     You should stop by that gas station to go to the bathroom.   On the other hand, I usually use must for things that have to happen in a certain way; any other way would make that thing not to happen. The problem is that some people find this usage harsh, as they receive it like if I'm giving them an order.      You must cross the street to get to that store.   To me, it's just a depiction of reality, not an order. But I'm neither a native speaker nor a regular person. :-)  So, what's the proper use for must and should? Does this use differ among the English dialects? dpkg exit with error parsing file `/var/lib/dpkg/status`, what to do? When I try to install any software, I encounter this error, and therefore I cannot update.  Preconfiguring packages ... dpkg: error: parsing file '/var/lib/dpkg/status' near line 51245 package 'oracle-xe':  mixed non-coinstallable and coinstallable package instances present N: Ignoring file 'gcl' in directory '/etc/apt/sources.list.d/' as it has no filename extension N: Ignoring file 'gcl' in directory '/etc/apt/sources.list.d/' as it has no filename extension E: Sub-process /usr/bin/dpkg returned an error code (2) Finding the closest Geometry in PostGIS Is the notorious $n^2 + n + 41$ prime generator the last of its type? Analogue of closed graph theorem This is the analogue of closed graph theorem for compact space          Suppose that $X$ and $K$ are metric spaces, that $K$ is compact, and that the graph of $f: X \rightarrow K$ is a closed subset of $X \times K$. Prove that $f$ is continuous.      Because metric space is first countable, all we need is to prove that if $x = \lim_{n \rightarrow \infty} x_{n}$, then $f(x) = \lim_{n \rightarrow \infty} f(x_{n})$. Suppose $x = \lim_{n \rightarrow \infty} x_{n}$, then because $K$ is compact, sequence $\{f(x_{n})\}$ has a subsequence $\{f(x_{n_{i}})\}$ converge. Because the graph of $f$ is closed, we must have $\lim_{n \rightarrow \infty}\{f(x_{n_{i}})\} = f(x)$. All we need to prove now is $\{f(x_{n})\}$ converge to $f(x)$, but I can't prove that. Can any one help me. I really appreciate. Thanks is looking bad right now. No errors in the console, but the following files have no content:         The CSS on another subdomain works fine though: As soon as I start SQL Server with no application querying, in the task manager it starts to consume memory very fast till it consumes around 15GB. How can I resolve this issue?