When I look for my error key number 0429ACCAF7AA50B3, it is not in the database, thus I cannot receive or generate anything even none of this did not work:      Please, do you know what to do next? Thank you!  This is what it shows:  $ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 0429ACCAF7AA50B3 [sudo] password for jiri:  Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.ag55619bV6 --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d/nilarimogard-webupd8.gpg --keyring /etc/apt/trusted.gpg.d/webupd8team-y-ppa-manager.gpg --keyserver keyserver.ubuntu.com --recv-keys 0429ACCAF7AA50B3 gpg: requesting key F7AA50B3 from hkp server keyserver.ubuntu.com gpgkeys: key 0429ACCAF7AA50B3 not found on keyserver gpg: no valid OpenPGP data found. gpg: Total number processed: 0
Possible Duplicate:    I am using 10.04 LTS - Lucid Lynx. I shutdown the computer while a software update was running. Then after I restarted my computer and while the update manager was running, I got this error:  Could not download all repository indexes The repository may no longer be available or could not be contacted because of network problems. If available an older version of the failed index will be used. Otherwise the repository will be ignored. Check your network connection and ensure the repository address in the preferences is correct. GPG error: http://toolbelt.herokuapp.com ./ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C927EBE00F1B0520 Failed to fetch  http://ppa.launchpad.net/rabbitvcs/ppa/ubuntu/dists/**DISTRIBUTION**/main/binary-i386/Packages.gz 404  Not Found   I went through the answers to  and I tried this $ sudo launchpad-getkeys  Please wait... launchpad-getkeys is running an update so it can detect the missing GPG keys Trying to import all the missing keys gpg: requesting key 0F1B0520 from hkp server keyserver.ubuntu.com gpgkeys: key C927EBE00F1B0520 not found on keyserver gpg: no valid OpenPGP data found. gpg: Total number processed: 0 launchpad-getkeys has finished importing all missing GPG keys.  Try running sudo apt-get update - you shouldn't see any key  errors anymore  But when I run sudo apt-get update again, it again shows that the key was not found on the keyserver. How to solve this problem?
When should titles like "captain" or "admiral" be capitalized? Please excuse the contrived example below, but I am wondering if this example is properly capitalised? I'm assuming that capitals are used when addressing someone directly, but lower case is used elsewhere. Can someone give some rules on this?      The captain walked into the room.    "Hi, Captain," said the admiral.   "Hi, Sir," replied the captain.   "Call me Admiral."   "Hi Admiral."   The captain and admiral stepped forward.   "Prime Minister, this is Captain Jones," said Admiral Brown.   "Pleased to meet you," said the prime minister. Redefine default color of todonotes Does the 2020 Apple M1 MacBook Pro support 2x daisy chained Thunderbolt Displays? The Apple Silicon based  supports Thunderbolt version 3 and I'm wondering if anyone has tried connection one to an ? Of course you'd need to use one of Apple's Thunderbolt 3 to Thunderbolt 2 converters. I also understand that this version is limited to supporting only a single 4K or 6K display, but since the original Apple Thunderbolt Display is only 2K I’d want to try and daisy chain these. Can I run more than one external display from the Apple Silicon M1 CPU/GPU based MacBook Pro (or Air)? There are no interfaces on which a capture can be done Available space not changing when resizing a partition Suppose $G=\{a_1,...,a_n\}$ is a finite abelian group, and let $x=a_1a_2\dotsm a_n$.   Prove that if there is more than one element of order $2$ then $x=e$.   What I've done so far: (#1 is just for illustration, There should be at least $3$ such elements)   $G$ has an even number of elements with order $&gt;2$ (They are paired so: $(a,a^{-1})$ ). And then there are $e$ and $\{b|o(b)=2\}$. Also, if $G$ has at least one element of order 2 then $|G|$ is even (Lagrange). Thus $|\{b|o(b)=2\}|$ must be odd. If there is exactly one element $b$ of order $2$ then $x=b$. That's because $G$ is abelian, and we can write: $x=e\cdot b\cdot(a_1 a_{1}^{-1}\dotsm a_n a_{n}^{-1})=b\cdot(e\dotsm e)=b$. If there are exactly $3$ such elements $a,b,c\in G$, then, as shown above, $x=abc$ and thus $x=e$ (That's because $(abc)^2=a^2b^2c^2=e$ which means $abc\in \{a,b,c,e\}$. If $abc=a$ then $b=c^{-1}=c$ which is false, same goes for $abc=b,abc=c$.)   I haven't managed to find a reason why the claim must hold for $5, 7, ...$ (i.e. All other odd integers). Does anyone have an idea?  Thanks in advance. Please excuse my English.  edit: Not a canonical answer but a simple one (if such even exists). Community user "stealing" tags? Why can templates only be implemented in the header file? Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.) I installed Ubuntu 17.10. Now I am having trouble with gksu:  $ gksu -dg synaptic No ask_pass set, using default! xauth: /tmp/libgksu-HgUjgQ/.Xauthority STARTUP_ID: gksu/synaptic/8760-0-alex-XPS-15-9530_TIME4974977 cmd[0]: /usr/bin/sudo cmd[1]: -H cmd[2]: -S cmd[3]: -p cmd[4]: GNOME_SUDO_PASS cmd[5]: -u cmd[6]: root cmd[7]: -- cmd[8]: synaptic buffer: -GNOME_SUDO_PASS- brute force GNOME_SUDO_PASS ended... Yeah, we're in... Unable to init server: Could not connect: Connection refused (synaptic:8767): Gtk-WARNING **: cannot open display: :1 xauth: /tmp/libgksu-HgUjgQ/.Xauthority xauth_env: (null) dir: /tmp/libgksu-HgUjgQ   If I don't use -g, the password dialog is disabled. So looks like a problem with creating a tty for root.  Any advice? The  (click on your number of helpful flags in your profile) is cool, however some posts have a gray background, some don't. What does it mean?  example: How can I install packages without starting their associated services? As you're probably aware, by default when you install a package on a Debian or Ubuntu based system, if the package contains a service, that service will generally be enabled and started automatically when you install the package.  This is a problem for me.  I've found myself needing to manage templates for building LXC containers. There are several containers, each corresponding to a Debian or Ubuntu release. (There are also Red Hat-based containers, but they aren't relevant here.)  /var/lib/libvirt/filesystems/debian6_template /var/lib/libvirt/filesystems/debian7_template /var/lib/libvirt/filesystems/ubuntu1004_template /var/lib/libvirt/filesystems/ubuntu1204_template   Occasionally I will find that the templates have a missing package or need some other change, so I will chroot into them to install the package. Unfortunately when I do that, I wind up with several copies of the package's service running!  By way of example, I found the templates didn't have a syslog daemon, so I installed one:  for template in /var/lib/libvirt/filesystems/{debian,ubuntu}*_template; do     chroot $template apt-get install rsyslog done   And promptly wound up with four copies of rsyslog running. Not to mention two copies of exim4. Oops!    I read somewhere (though I can't find it again now) that it's not supposed to start services when running in a chroot, but that clearly isn't happening here.  One potentially viable  calls for temporarily replacing the various commands which actually start services, such as start-stop-daemon and initctl, though this is a lot more work than I really wanted to do. If I have no other choice, though...  The ideal solution here would be for Debian-based systems to stop doing this crap, but failing that, perhaps an obscure or undocumented command line option for apt-get?  In case it wasn't clear, I really want to keep anything related to managing the templates outside the templates, if possible. When did UX start being called UX? When did people start talking about User Experience as a role/domain similar to the way that it's used today?  The earliest reference I can find is the Norman, Miller, Henderson CHI 95 piece on Apple's set up (Donald Norman, Jim Miller, Austin Henderson: What You See, Some of What's in the Future, And How We Go About Doing It: HI at Apple Computer. Proceedings of CHI 1995, Denver, Colorado, USA)  Anything earlier?  [Edit - after @Andrew's nice answer we have 1993 as an earlier date     "I invented the term because I thought Human Interface and usability   were too narrow: I wanted to cover all aspects of the person's   experience with a system, including industrial design, graphics, the   interface, the physical interaction, and the manual." - Don Norman   ]  (I'm writing a talk on communities of practice relating to UX - and want to get my time lines right ;-) How can I run a specific command for each find result? How would one run a specific command for each file that was found by using the find command? For the purpose of the question lets say that I would simply like to delete each file found by find. Returning a const reference to an object instead of a copy How to get the CPU cycle count in x86_64 from C++? Showing that $e^z=z$ has infinitely many solutions One of our review problems for my complex analysis final is the following:     Show that $e^z=z$ has infinitely many solutions in $\mathbb{C}$.   I've seen a few solutions online, but none of them have used material that was covered in our introductory complex analysis course. Would anyone be able to provide a simple solution?  I'm trying to think of ways to invoke bounding in some way but I can't seem to come up with anything. Why does list(my_list) modify the object? How to change material's color in blender game engine? How to show that $\int_{0}^{\pi}{\sin^5 x\over 1+\cos^3 x}\mathrm dx=\ln 3?$ Given the integral $(1)$     $$\int_{0}^{\pi}{\sin^5 x\over 1+\cos^3 x}\mathrm dx=\ln 3\tag1$$   This integral seems to be quite tough, I can't even know where to start. I have try substitution $u=1+\cos^3 x$ and $u=\cos^3 x$, can seem to remove the x variables.  We have the following identities   $$\sin^5a={5\over 8}\sin a-{5\over 16}\sin 3a+{1\over 16}\sin 5a\tag2$$  $$\cos^3 a={3\over 4}\cos a+{1\over 4}\cos 3a\tag3$$  We may write $(1)$ as  $$\int_{0}^{\pi}{\sin x(1-\cos^2 x)^2\over 1+\cos x(1-\sin ^2 x)}\mathrm dx\tag4$$  $u=1-\sin^2 x\implies \mathrm du=-2\sin x\cos x\mathrm dx$ then $(4)$ becomes  $${1\over 2}\int_{0}^{1}{(1-u)^2\over \sqrt{u}+u^2}\mathrm du\tag5$$  $u=v^2\implies du=2vdv$ then $(5)$ becomes  $$\int_{0}^{1}{(1-v^2)^2\over v+v^4}\cdot{v\mathrm dv}\tag6$$ Simplify to  $$\int_{0}^{1}{(1-v)(1-v^2)\over 1-v+v^2}\mathrm dv\tag7$$  I guess using partial decomposition of fraction and integrate term by term, seem lengthy process  How else can we prove $(1)$? I want to uninstall and completely remove QGIS installation from my computer(windows vista). I have uninstalled it and when i try to reinstall it says it is already installed on the system.