I want to install Tkinter in python 2.7.9 I tried sudo apt-get update sudo apt-get install python-tk i even tried to upgrade python so as to install Tkinter but that didn't work either. Everytime i try to install this is what comes  sudo apt-get install python-tk  Reading package lists... Done  Building dependency tree    Reading state information... Done  Package python-tk is not available, but is referred to by another package.  This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'python-tk' has no installation candidate
Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc
Proving $\frac{\sin x}{x} =\left(1-\frac{x^2}{\pi^2}\right)\left(1-\frac{x^2}{2^2\pi^2}\right) \left(1-\frac{x^2}{3^2\pi^2}\right)\cdots$ How to prove the following product? $$\frac{\sin(x)}{x}= \left(1+\frac{x}{\pi}\right) \left(1-\frac{x}{\pi}\right) \left(1+\frac{x}{2\pi}\right) \left(1-\frac{x}{2\pi}\right) \left(1+\frac{x}{3\pi}\right) \left(1-\frac{x}{3\pi}\right)\cdots$$ I don't know how to integrate $\displaystyle \int\frac{1}{x^{4}+1}\mathrm dx$. Do I have to use trigonometric substitution? The strange thing is that opened scripts or newly opened ones are working fine. It's the new created C# scripts that are not working.  With not working, I mean the MonoBehaviour is not in light blue color it's in black color. In this screenshot I took, I marked it with a red circle.    What have I tried so far? I have closed Visual Studio and started over again.  Since it didn't solve it, I closed the unity editor and started it over again, to no avail.  I pressed 'clean solution', I pressed 'rebuild solution', I pressed 'build solution'.  What else can I do ? And why are the other scripts working fine? If I type gameo...it will auto complete it to GameObject but in this specific script it's just not working.  This is a screenshot of the editor. I have in the Hierarchy a Ladder object.  In the Assets I created a folder name Ladder and a script name Ladder. But this Ladder script is not working.    This is the Ladder script and this script was working before but once I created another script inside the ladder folder name Raise empty script the Raise script didn't work and now the Ladder is not working either. But other scripts are working fine.  using System.Collections; using System.Collections.Generic; using UnityEngine;  public class Ladder : MonoBehaviour {     public Transform charcontroller;      private bool inside = false;     private float heightFactor = 3.2f;      private void OnTriggerEnter(Collider other)     {             inside = true;     }      private void OnTriggerExit(Collider other)     {             inside = false;     }      private void Update()     {         if (inside == true &amp;&amp; Input.GetKey("w"))             charcontroller.transform.position += Vector3.up / heightFactor;     } } Apache and systemd I've just started using Debian 8 which has introduced systemd. I'm not interested in the politics around SysV vs systemd, but I am confused, especially around Apache (2.4).  There are now two ways to restart apache:   apache2ctl restart or apache2ctl graceful systemctl restart apache2 and it seems systemctl restart apache2.service does the same thing.   And they appear to do different things(!). I don't understand the difference.  I seem to need to do both to get a proper full restart working. e.g. after changing a config file for the php module it only noted the change after both.  Another time when apache2ctl configtest was failing and the failure was reported in systemctl status apache2 I fixed the config so that the first of these commands was happy, restarted with apache2ctl restart but the systemd status command still listed it as not running and with the old config problem.  I promise to spend ages reading about systemd (RTFM) in depth at some point, but meanwhile on a practical level relating to apache, I'd appreciate advice. How can I run an external program from C and parse its output? I've got a utility that outputs a list of files required by a game.  How can I run that utility within a C program and grab its output so I can act on it within the same program? UPDATE: Good call on the lack of information.  The utility spits out a series of strings, and this is supposed to be portable across Mac/Windows/Linux.  Please note, I'm looking for a programmatic way to execute the utility and retain its output (which goes to stdout). If a normal subgroup $N$ of order $p$($p$ prime) is contained in a group $G$ of order $p^n$,then $N$ is in the center of $G$. If a normal subgroup $N$ of order $p$($p$ prime) is contained in a group $G$ of order $p^n$,then $N$ is in the center of $G$.   I want to use induction to prove this:  It is trivial when $G=p(n=1)$, assume $G=p^n$, $N$ is a normal subgroup in $G$ with order $p$. Since $G$ is p-subgroup, $G$ has a normal subgroup $H$ with order $p^{n-1}$,according to assumption, $N \subset C(H)$. But I don't know how to go on, is $C(H)=C(G)$?Can induction work in this case? Can't Use /Summon Command Password Protect QGIS project On a shared computer, I have a QGIS project which links up to a PostGIS database that contains my data. If a user wants to access layers from the db, they have to enter the db credentials, so that's OK.   However, I have previously logged on and imported layers from my db into QGIS, and manipulated them in QGIS (styling options based on meta-data, etc.)... Anybody who opens my QGIS project can view these layers in QGIS, and can therefore see the data I wish to be protected in my db.  Is there a way to password protect my QGIS project? All I want to do is to check whether an element exists in the vector or not, so I can deal with each case.  if ( item_present )    do_this(); else    do_that(); Command with percent symbols not running in crontab The following crontab does not work:  # TEST LINE DOES DOT RUN */1 * * * * /bin/echo 'test '`/bin/date +%Y-%m-%d` &gt;&gt; /tmp/test   I also tried starting it with:  SHELL=/bin/bash   Update: I thought the backtick characters ` were the villains, but as the answer below clarifies the percentage % was the culprit! How to draw simple table Finding the Mobius Transformation that maps open unit disk onto itself Hi I am trying to find all the Mobius transformations that map unit open disk onto itself i.e., if $|z|&lt;1$ then $|f(z)|&lt;1$ where $f(z)=\frac{az+b}{cz+d}$. I did so far \begin{align*} &amp;\Big|\frac{az+b}{cz+d}\Big|&lt;1\\ \Rightarrow &amp; |az+b|&lt;|cz+d|\\ \Rightarrow &amp; |az+b|^2&lt;|cz+d|^2\\ \Rightarrow &amp; |az+b||\bar{a}\bar{z}+\bar{b}|&lt;|cz+d||\bar{c}\bar{z}+\bar{d}|\\ \Rightarrow &amp; |a|^2|z|^2+|b|^2+2\text{Re }(az\bar{b})&lt;|c|^2|z|^2+|d|^2+2\text{Re }(cz\bar{d}) \end{align*}   After that I am stuck. Can anyone help me. I would be obliged...Thanks in advance. What currency does the galaxy deal in besides credits? In APM and the Clone Wars series, among other media, there are frequent instances where Republic credits are not accepted. These are typically places outside of the Republic and especially in the criminal underworld, Republic or otherwise.  If Anakin wants to pay Hondo to deliver some missiles illegally and not ask any questions, and Hondo does not accept credits, then what does Anakin pay him off with? Having migrated to Linux from Windows, I would like to find an alternative software to Winmerge or rather learn command line tools to compare and sync two folders on Linux. I would be grateful if you could tell me how to do the following tasks on the command line... (I have studied diff and rsync, but I still need some help.)  We have two folders: "/home/user/A" and "/home/user/B"  Folder A is the place where regular files and folders are saved and folder B is a backup folder that serves as a complete mirror of folder A. (Nothing is directly saved or modified by the user in folder B.)  My questions are:   How to list files that exist only in folder B? (E.g. the ones deleted from folder A since the last synchronization.) How to copy files that exist in only folder B back into folder A? How to list files that exist in both folders but have different timestamps or sizes? (The ones that have been modified in folder A since last synronization. I would like to avoid using checksums, because there are tens of thousands of files and it'd make the process too slow.) How to make an exact copy of folder A into folder B? I mean, copy everything from folder A into folder B that exists only in folder A and delete everything from folder B that exists only in folder B, but without touching the files that are the same in both folders. Is this correct? "One of the things that makes him great is..." One of the things that makes him great is he brings it every night.   I'm pretty sure it should be that make him in the plural, because one of the things is referring to a lot of things and a lot of things should take a plural verb. But I always hear native speakers in America say it in the singular, so with an s.  Another example:     This is one of the responsibilities that comes with greatness and he understands that.   Native speakers always use the verb in the singular (here, comes) even though [I believe] it is grammatically incorrect to use the singular form of the verb there. How can I capitalize the first letter of each word in a string in Perl? My 5 year- old daughter is constantly defiant! My 5-year old daughter is very defiant.  It started getting bad about 6 months ago. She doesn't do what she is told, and any time she hears the word "no" she throws terrible, dramatic fits, screaming ridiculously loud, and in some cases hitting.  She refuses to make eye contact when I warn her to stop doing something even when I am down at her eye level and it takes multiple orders to finally get her to look at me. She constantly tells me no.  I feel like I constantly tell her no and that she feels this gives her the right to tell her father and I no.  I have tried time outs which are not effective at all; she only throws a fit the whole time, never seeming to run out of wind. Spankings are only effective until the shock of the action itself wears off and then she returns to the same behavior.  My husband and I recently took away ALL of her toys/ possessions being she is a pretty materialistic child (she loves getting toys and always wants something new). We told her that if she was good and listened and stopped telling us no and throwing fits, that after three days we would let her choose three boxes of toys to bring back in her room. This worked but as soon as she got those three boxes unpacked, we packed them back up because she went right back to the no's and fit-throwing within a few hours.  I am mainly the one disciplining her and I feel she is definitely the most defiant with me. I believe in explaining to her why things are not OK and why I tell her no, but I really don't feel it helps and I never feel as if she listens to what I tell her.  I am at my wits' end and feel like a failure of a mother. She is my first and only child, and the only grandchild on both sides of our family. She is an angel at school but home is completely different.  I need help figuring this out but nobody I talk to really has any advice for me. I am at the point where I am wondering if she or I need counseling because I feel out of options. The camera in Far Cry 3 is useful for tagging enemies from a distance but also includes the ability to take pictures.  This does not seem to do anything useful when used on animals or enemies.  Is there a purpose? How check if a picklist value is available or not for a specified record type ( through SOQL)? Thanks in advance How to create a Windows 7 installation USB from OS X? I'm trying to create a Windows 7 installation USB (for use on a PC) from OS X.  I've tried following these instructions from a :   Insert the USB flash drive and run the command diskutil list to find out the disk name, we'll use /dev/disk1 as an example Now unmount the disk using diskutil unmountDisk /dev/disk1 dd if=/path/to/Win7.iso of=/dev/disk1 bs=8192   But the instructions don't work. When I insert the created USB drive into my PC and try to boot from it, I get this message:     Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key   What am I missing?