Why is `apt-get update` telling me to run `apt-get update`?
How to fix "W: Duplicate sources.list entry"?
Can I get SSH to use an askpass program even if it was run from a terminal? says:  SSH_ASKPASS    If  ssh needs a passphrase, it will read the passphrase from the    current terminal if it was run from a terminal.  If ssh does not    have  a  terminal associated with it but DISPLAY and SSH_ASKPASS    are set, it will execute the program  specified  by  SSH_ASKPASS    and open an X11 window to read the passphrase.   I'd like SSH to use an askpass program even if it was run from a terminal.  On occasion, I have to connect to servers, where there's some delay in showing a password prompt (maybe due to network issues, maybe due to attempted reverse DNS lookups, …). I get annoyed and switch to something else, and forget about the attempted connection. (Insert joke about attention span of a goldfish.) When I finally get back to it, the prompt's timed out and even a correct password would just result in a closed connection.  Keys would be one solution, but not every system I use has my usual SSH keys. However, I usually use Ubuntu systems, and Ubuntu has an SSH askpass program installed by default.  If an askpass window popped up, however, I'd be immediately aware of it. That's a good enough compromise for me, if only I can get it to work. Why do the $n \times n$ non-singular matrices form an "open" set? Why is the set of $n\times n$ real, non-singular matrices an  open subset of the set of all $n\times n$ real matrices? I don't quite understand what "open" means in this context.  Thank you. I'm using wordpress multiste 3.3.1 I'm not gonna update it in the future. So I disabled all upgrade functions.  I want to remove the wordpress admin bar from both frontend as well as dashboard.  I can remove it from frontend using this code.  add_action( 'init', 'disable_admin_bar', 1 ); function disable_admin_bar() {     add_filter( 'show_admin_bar', '__return_false' ); }   But i couldn't find any solution to remove it from dashboard.   I don't want to use css solution to hide admin bar and I'm ready to edit the core files to remove it  Can anyone help me to remove it completely?. Thanks How much Valyrian steel is there that is unused for link making and why aren't people making weapons out of it? I want to copy the data folders from a previous ubuntu(14.04) partition My hard drive is a mess and I want to reformat it and do a fresh install of 16.04. My problem is I only have access to the HDD via 16.04 on a USB stick and although I can navigate to the various folders, nothing I do allows me to copy to an external hard drive. The folders are not encrypted. I also have a small swap partition - I would like to preserve the data on that too if possible.  Here's a listing of the home directories on the drive:  ubuntu@ubuntu:/$ ls -l /media/*/*/home /media/ubuntu/0e228f65-dac7-435f-828b-1eb1a6c3f29a/home: total 4 drwxr-xr-x 46 1000 1000 4096 Dec 21  2015 simon  /media/ubuntu/db79a6d1-7c6c-4d8c-822b-ba6ccd1ddecd/home: total 4 drwxr-xr-x 27 1000 1000 4096 Apr 17  2014 simon  /media/ubuntu/ebe2a6ba-9cb5-4279-8352-5082b8dd4d5e/home: total 4 drwxr-xr-x 39 1000 1000 4096 Aug  3 14:21 simon Windows 10 - Users already logged in at boot Index of the center of a group in the group is not a prime number The question is to prove index of $Z(G)$ in $G$ is not a prime number.    We know that $|G:Z(G)|=|G:C_G (x)||C_G (x):Z(G)|$ where $C_G (x)$ means centralizer of $x \in G$  I want to mention that we do not want to use $G⁄Z(G)$ theorem.   We may assume that $|G:Z(G)|=p$ where $p$ is a prime. How to change the date format? Presently the date is showing as mmm dd hh:mm:ss. Is there any way that I can change it to as per my liking. For example : dd mmm, hh:mm:ss. Plot Option Precedence while combining Plots with Show[] How can I easily share links or text between my Android phone and my laptop? Clarify or visualize the parameters involved for receiving the Curious badge How to add vertical space after \hline without breaking vertical lines in a table I have seen similar questions on the matter (, ) of adding vertical space and not breaking vertical lines, the solutions suggested are to add space after the \\ using \\[0.1cm] for example or changing the \arraystretch which I do not want to do. Using \\[0.1cm] allows me to add space just before a \hline but not after as well.  How can I add vertical space after a \hline without breaking vertical lines in a table?  Please find my MWE below:  \documentclass{scrreprt} \usepackage{setspace} \usepackage[left=2.5cm,right=2.5cm,top=3cm,bottom=3cm]{geometry} \usepackage{array,tabularx} \doublespacing  \begin{document} \begin{table}[htb]   \centering   \onehalfspacing   \caption{Table of info.}      \begin{tabular}{c | c c}  &amp; C/S Analyser &amp; O/N/H Analyser \\  &amp; EMIA 320 V2 &amp; EMGA 830 \\[0.1cm]    \hline    \noalign{\vskip 0.1cm} Sensitivity (ppm) &amp; 0.1 &amp; 0.001 \\ Furnace type &amp; Induction &amp; Impulse \\ Carrier gas &amp; Pure O2 &amp; Pure He \\[0.1cm]    \hline     \end{tabular}    \doublespacing   \label{tab:chem} \end{table} \end{document} Solving an ODE in power series (Pardon if this seems a bit beginner, this is my first post in math - trying to improve my knowledge while tackling Project Euler problems)  I'm aware of Sigma notation, but is there a function/name for e.g.  $$ 4 + 3 + 2 + 1 \longrightarrow 10 ,$$  similar to $$4! = 4 \cdot 3 \cdot 2 \cdot 1 ,$$ which uses multiplication?   Edit: I found what I was looking for, but is there a name for this type of summation? How do I extract all the external links of a web page and save them to a file? Finding all solutions for a system of equations with constraint on the sum of absolute values I am looking for a fast algorithm to find all integer solutions for the following system of linear equations ($c_1,\ldots,c_n \in \mathbb{Z}$ and $r\in \mathbb{N}$ ):  $x_1+x_2=c_1$  $x_3+x_4=c_2$  ...  $x_{2n-1}+x_{2n}=c_n$  $|x_1|+|x_2|+\ldots+|x_{2n}|=r$  $x_1,\ldots,x_{2n} \in \mathbb{Z}$   Also can we find the number of solutions before solving the system? Effect on loading a DC motor - load torque Could someone give a (detailed) explanation (perhaps with formulas) of how the load (torque) affects the armature current of a DC motor (separately excited or shunt or series)?  As the load torque increases the speed of the motor decreases, and assuming the terminal voltage stays constant, the EMF will become lower and thus the armature current will increase.  But could someone give me the formula that shows the relation between load torque and armature current?  Is it something like:   \$T_\text{developed} = T_\text{shaft} + T_\text{friction windage} + T_\text{load}\$ ,   where \$T_\text{developed} = K \, \text{flux}_\text{pole} \,I_\text{armature}\$ ?  But then you have  \$P_d = P_s + P_{f_w} + P_l   \$  where \$P_d = K \,\text{flux}_\text{pole}\, I_\text{armature}  \,\omega_m\$  In the last formula you can't see that as the increase due to \$P_\text{load }\$ the armature current increases because maybe someone can say the speed \$\omega_m\$ increases.  And how come at no-load the armature current and thus the torque developed is zero? Is it really zero, or do I have to assume there is some current flowing?  Could also explain me the principle of torque developed. Because at no load, the shaft torque is equal to torque developed, right? After writing the FreeNAS IMG to a 16 GB USB flash drive, I can now only use 938 MB. I used the Win32 Disk Imager tool to write the IMG to the device. Then later, when I inserted the the USB drive into my Windows 7 computer it said that it had to be formatted, because it couldn't read it. I believe this is normal. So I formatted it inside Windows using the format option when prompted. So in Windows Explorer now, 938 MB is reported as capacity of this device.    Also, when i check the properties dialog box I can see the same numbers.    And when I check with diskmgmt.msc I can see there are several volumes I don't recognize and unallocated space of 12.79 GB.    Now, I have another 2 GB USB flash drive with the same problem. It too was used for FreeNAS, and it too has a reported capacity of only 938 MB. I thought it was broken there for a while, until I saw the same problem with this 16 GB model.  I tried using diskpart on the 2 GB model, and I saw that there were several partitions there (list partitions) just like on this one. So I used the clean option to try to wipe it, but that wiped off everything so it's totally useless now. I'm not sure how to rebuild it.  Is this a standard routine, like part of the whole "user experience", that whenever you make a bootable USB falsh drive with FreeNAS, it messes up your device? I am new to FreeNAS, so i wouldn't know. But it sure looks like it. Maybe it is in fact the format operation in Windows that messes things up... I don't know. It's not very nice.  How do I restore the capacity back to 16 GB-ish (14.9 GiB)? Topological/Geometrical justification for $\text{CFT}_2$ being special It is known as a fact that conformal maps on $\mathbb{R}^n \rightarrow \mathbb{R}^n$ for $n&gt;2$ are rotations, dilations, translations, and special transformations while conformal maps for $n=2$ are from a much wider class of maps, holomorphic/antiholomorphic maps. I was wondering to know if there is any topological or geometrical description for this.   To show what I mean, consider this example: in $\mathbb{R}^n$ for $n&gt;2$ interchanging particles can only change the wave function to itself or its minus. It is related to the fundamental group of $\mathbb{R}^n-x_0$ ($x_0$ is a point in $\mathbb{R}^n$ and $\pi_1(\mathbb{R}^n-\{x_0\})=e$ for $n&gt;2$) but this is not true for $n=2$.   I want to know whether exists any topological invariant or just any geometrical explanation that is related to the fact that I mentioned about conformal maps on $\mathbb{R}^n$. Loading a .X model in DirectX 9