Upgrade begins in the terminal, runs for a few minutes downloading 'trusty' packages and then stops with the error message below:  W:Failed to fetch  http://extras.ubuntu.com/ubuntu/dists/oneiric/main/source/Sources 404  Not Found  E:Some index files failed to download. They have been ignored, or  old ones used instead.  Restoring original system state Aborting   Note the 'oneiric' - I did upgrade from oneiric to precise a few years back and have always got error messages when updating, referring to 'oneiric'. I have tried to follow advice on here for upgrading and have not found and other questions that have given me the answer to this puzzle.
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
How to turn off "unread messages" feature on Windows XP login screen? In Windows XP, if you have logged onto Windows Live Messenger at some point, then it'll start displaying how many unread messages on the Windows login screen. How can I turn it off? When I click the bounty info icon on the iOS app. The added bounty description and reason is not shown.  For example: I have a cryptography workshop question I'm having trouble with as follows;  Person A creates a cipher $E_k(m)$ which produces a ciphertext from message $m$ using key $k$. The function inside $E$ is kept secret but the length of $E_k(m)$ is known.  Person B recommends "increasing" security of the cipher by instead doing :   $(E_k(m) \oplus m)\ ||\ (E_k(m) \oplus 1111...11)$      Does this in fact increase security of the cipher or increase new problems.  My thinking is, depending on the function within $E$, xoring the output of the cipher with the plaintext message $m$ could expose the key $k$, meaning the extra complexity is for nothing. Am I on the right track, or am I missing something?  I have tried searching for examples of similar schemes and found nothing (which probably means it's not a good scheme) but I need to justify my answer.   Any steers in the right direction would be greatly appreciated, I'm more than happy to do the research myself just unsure what specifically to look for.   Unfortunately the above context is all I have been provided for this question. Let $f(z)=\frac{1}{(z-1)(z-2)}$ and $g(z)=\frac{z}{(z-1)(z-2)}$. Let $\gamma$ be the circle of radius 4 centered at the origin and traveled once in the counterclockwise direction. Let $A=\{ z \in \mathbb{C}: |z|&gt;3 \}$  1) I need to show there is no analytic function $G: A \to \mathbb{C}$ such that $G'(z)=g(z)$ for all $z$ in $A$.   2) I also need to show that there is an analytic function $F:A \to \mathbb{C}$ such that $F'(z)=f(z)$ for all $z$ in $A$.  Do I have to integrate to find such function? Every issue of Ubuntu LTS since 8.04, I have made a Full install of Ubuntu to USB flash drive, and recorded each step..  This has been intended to make a guide/check list for users wishing to create Full install bootable flash drives.  Previously the procedure worked for BIOS boot if created in BIOS and for UEFI boot if created in UEFI.  This year for 20.04 the instructions should work for both creating and running the drive booted from either BIOS or UEFI.  The question is:  How to Create a Full Install of Ubuntu to USB device with Step by Step instructions that work in either BIOS or UEFI. App Store is stuck in a loop trying to download a free app -- how do I make it stop? My App Store keeps saying this item is free in the store, that this item will be added to your purchases and it then says cancel or download.   I click download and it won't download and keeps popping up the same message over and over again.  How do I make it stop? I can't download any apps. I'm developing a Custom Post Type plugin, which works fine in dev. Now that I've moved it to production, I'm getting a 404 when I try to display the template for the CPT.   So, two questions:  1- Is there some mechanism to determine the path WP took to get through the hierarchy?  2- Why wouldn't it just give me the single or index page?  I've dumped $wp_query and a stacktrace at the end of the 404. Here's part of what I found:  [query] =&gt; Array     (         [page] =&gt;          [pagename] =&gt; refletters/proximity     )  [request] =&gt; SELECT   wp_posts.* FROM wp_posts  WHERE 1=1  AND (wp_posts.ID = '0') AND wp_posts.post_type = 'page'  ORDER BY wp_posts.post_date DESC  [posts] =&gt; Array     (     )  [queried_object] =&gt;  [queried_object_id] =&gt; 0   And the stack trace:  2013-04-27 22:16:41 - 24.52.197.40 - TRACE - index.php - 404.php[39] -      wordpress/wp-content/themes/notoriousconsultant/404.php[39] - aaLog-&gt;logtrace     wordpress/wp-includes/template-loader.php[50] - include     wordpress/wp-blog-header.php[16] - require_once     wordpress/index.php[17] - require   Thanks for your help. How do I download a YouTube video? CDF of absolute value of difference in random variables Move EFI System Partition to another drive The mediation package in R returns results in which:   Average Direct Effect (ADE) (the unmediated effect) is not statistically significant The Average Causal Mediated Effect (ACME) (the effect of the mediator alone) is positive and statistically significant The Total Effect (ADE+ACME) is larger than the ADE and ACME alone, positive and statistically significant   Does this indicate that the variable being mediated can only act through the mediator DV? I'm not quite certain as to how this would be interpreted.  Thank you for any help. tmux: shared session, one user in a pane, another in another pane, two different cursors I've decided to try tmux: have been reading the docs and googling around, trying to find a way to have two users sharing a session, each with a different cursor.  However, giving 777 permissions to the socket, or creating a group, chgrping the socket and adding both users to it, seems to let that same socket be used to share a session with only one cursor: both users can write, but always in the same cursor position.  Right now both users are in the same home server over ssh, and the idea is to be able to have:   A terminal in a, let's say, left pane, where I can type commands Another terminal in a right pane, where I can see another user typing commands  in his own terminal The same thing for the other user   What I'm doing at the moment is using two sessions (not shared) and a script -f and tail -f combination that kinda works for reading each other's key strokes, but I reckon there is probably some way of doing this using tmux sharing capabilities.  Is there a way to get this idea working with write support in each other's terminal?  What is the better way to do this? Time limited and band limited signal Why can't I catch Pokemon in Pokemon Go anymore? 32-bit, 64-bit CPU op-mode on Linux I'm confused. Running Fedora Linux, lscpu yields:  Architecture:            i686 CPU op-mode(s):          32-bit, 64-bit ...   But when I try to install a 64-bit program (Chrome) I get error like:     Package /....x86_64.rpm has incompatible architecture x86_64. Valid architectures are ['i686', 'i586', 'i486', i386']   I'm less interested in being able to install Chrome and more interested in why lscpu says that my CPU can run in 64-bit mode; clearly this can't mean I can run 64-bit programs. Can anyone clarify? When and how do we use the different kinds of brackets/parentheses&nbsp;— (){}[]&nbsp;— while writing English (not code)? sudo: /var/lib/sudo writable by non-owner (040777), should be mode 0700 I get error message always when I work with sudo command.  It shows always sudo: /var/lib/sudo writable by non-owner (040777), should be mode 0700.   A while ago I changed the permission of /var folder to 777.   How can I fix it? I want to write a program for this: In a folder I have n number of files; first read one file and perform some operation then store result in a separate file. Then read 2nd file, perform operation again and save result in new 2nd file. Do the same procedure for n number of files. The program reads all files one by one and stores results of each file separately. Please give examples how I can do it. I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an inverter means more cost (weight, controller, etc).  Are there any reasons for that? What are the differences between an AC and DC motor that may have lead to this decision? Also does anyone know what kind of motor is used in other electric cars? When did the red shirt careers change to yellow shirts in Star Trek and why?