I just copied a directory from a USB flash drive. I copied it from an NTFS drive and so all the files had execute permission.  I executed chmod -x * to undo the execute permission. Despite that, all the directories are showing with green background, which is normally only for executable files.  What could be the reason?  Attached image:
There are two directories shown by 'ls'.  Normally directories anywhere are blue on black background.  But the first one is blue on green and impossible to read.  Why is this?  How to make it blue on black, or at least something light on something dark?  This is on Ubuntu 12.04, using bash in Gnome Terminal.  In Konsole, the blue is slightly darker, and possible to read, though could be way better.
Example 4.21 in Baby Rudin: Why is the inverse of this function not continuous at this point? Here's Theorem 4.17 in the book Principles of Mathematical Analysis by Walter Rudin, 3rd edition:      Suppose $f$ is a continuous 1-1 mapping of a compact metric space $X$ onto a metric space $Y$. Then the inverse mapping $f^{-1}$ defined on $Y$ by $$ f^{-1}( f(x) ) = x \ \ \ \ \ \ \ ( x \in X ) $$ is a continuous mapping of $Y$ onto $X$.    Now in Example 4.21 Rudin illustrates that compactness of $X$ is essential in Theorem 4.17.   So here is Example 4.21:   Let $X$ be the half open interval $[0, 2 \pi )$ on the real line, and let $\mathbf{f}$ be the mapping of $X$ onto the circle $Y$ consisting of all points whose distance from the origin is $1$, given by $$ \mathbf{f}(t) = ( \cos t, \sin t ) \ \ \ \ \ \ ( 0 \leq t &lt; 2 \pi). $$ Then this function $\mathbf{f}$ is of course continuous and injective. But Rudin asserts that the inverse function is discontinuous at the point $(1, 0) = \mathbf{f}(0)$. How to demonstrate this fact rigorously?  So far in the book, Rudin has not discussed the functions $\cos$ and $\sin$. So can we come up with an example that uses only what Rudin has discussed? Explanation of the binomial theorem and the associated Big O notation How to understand the memory usage and load average in linux server I am using a linux server which has 128GB of memory and 24 cores. I use top to see how much it is used. Its output is pasted at the end of the post. Here are two questions:  (1) I see that each of the running processes occupies a very small percentage of memory (%MEM no more than 0.2%, and most just 0.0%), but how the total memory is almost used as in the fourth line of output ("Mem:  130766620k total, 130161072k used,   605548k free,   919300k buffers")? The sum of used percentage of memory over all processes seems unlikely to achieve almost 100%, doesn't it?  (2) how to understand the load average on the first line ("load average: 14.04, 14.02, 14.00")?   Thanks and regards!  Edit:  Thanks!  I also really like to hear some rough numbers based on used percentage of memory to determine if a server is heavily loaded, since I once became the one who cramed the server without understanding the current load.  Is swap regarded as almost the same as memory? For example, when memory and swap are almost of same size, if the memory is almost running out but the swap is still largely free, may I just view it as if the used percentage of memory + swap is still not high and run other new processes?  How would you consider together CPU or memory (or memory + swap) usage? Do you become worried if either of them reaches too high or both?  Output of top：  $ top    top - 12:45:33 up 19 days, 23:11, 18 users,  load average: 14.04, 14.02, 14.00 Tasks: 484 total,  12 running, 472 sleeping,   0 stopped,   0 zombie Cpu(s): 36.7%us, 19.7%sy,  0.0%ni, 43.6%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st Mem:  130766620k total, 130161072k used,   605548k free,   919300k buffers Swap: 63111312k total,   500556k used, 62610756k free, 124437752k cached    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND  6529 sanchez   18  -2 1075m 219m  13m S  100  0.2  13760:23 MATLAB 13210 timothy   18  -2 48336  37m 1216 R  100  0.0   3:56.75 absurdity 13888 timothy   18  -2 48336  37m 1204 R  100  0.0   2:04.89 absurdity 14542 timothy   18  -2 48336  37m 1196 R  100  0.0   1:08.34 absurdity 14544 timothy   18  -2  2888 2076  400 R  100  0.0   1:06.14 gatherData  6183 sanchez   18  -2 1133m 195m  13m S  100  0.2  13676:04 MATLAB  6795 sanchez   18  -2 1079m 210m  13m S  100  0.2  13734:26 MATLAB 10178 timothy   18  -2 48336  37m 1204 R  100  0.0  11:33.93 absurdity  12438 timothy   18  -2 48336  37m 1216 R  100  0.0   5:38.17 absurdity 13661 timothy   18  -2 48336  37m 1216 R  100  0.0   2:44.13 absurdity 14098 timothy   18  -2 48336  37m 1204 R  100  0.0   1:58.31 absurdity 14335 timothy   18  -2 48336  37m 1196 R  100  0.0   1:08.93 absurdity 14765 timothy   18  -2 48336  37m 1196 R   99  0.0   0:32.57 absurdity 13445 timothy   18  -2 48336  37m 1216 R   99  0.0   3:01.37 absurdity 28990 root      20   0     0    0    0 S    2  0.0  65:50.21 pdflush 12141 tim       18  -2 19380 1660 1024 R    1  0.0   0:04.04 top  1240 root      15  -5     0    0    0 S    0  0.0  16:07.11 kjournald  9019 root      20   0  296m 4460 2616 S    0  0.0  82:19.51 kdm_greet     1 root      20   0  4028  728  592 S    0  0.0   0:03.11 init     2 root      15  -5     0    0    0 S    0  0.0   0:00.00 kthreadd     3 root      RT  -5     0    0    0 S    0  0.0   0:01.01 migration/0     4 root      15  -5     0    0    0 S    0  0.0   0:08.13 ksoftirqd/0     5 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/0     6 root      RT  -5     0    0    0 S    0  0.0  17:27.31 migration/1     7 root      15  -5     0    0    0 S    0  0.0   0:01.21 ksoftirqd/1     8 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/1     9 root      RT  -5     0    0    0 S    0  0.0  10:02.56 migration/2    10 root      15  -5     0    0    0 S    0  0.0   0:00.34 ksoftirqd/2    11 root      RT  -5     0    0    0 S    0  0.0   0:00.00 watchdog/2    12 root      RT  -5     0    0    0 S    0  0.0   4:29.53 migration/3    13 root      15  -5     0    0    0 S    0  0.0   0:00.34 ksoftirqd/3 Why is the word 'number' abbreviated to 'No.' in UK English and '#' in American English? Why the disparity? And why use 'No.'? Is it from the French?  And the hash or pound sign seems a weird choice too, is there a history or any reason involved? shopt works in command line, not found when run in a script I'm writing a script to copy some files around, and trying to use shopt -s dotglob  like .jshint and whatnot.    I can run shopt -s dotglob directly at a bash prompt with no error.  However, running the script throws the error:  script.sh: 81: script.sh: shopt: not found   I'm running this script in bash shell, with the shebang header #!/usr/bin/env bash.  Error line:  shopt -s dotglob cp -r $TEMP/img/* $TARGET/img/ cp -r $TEMP/js/* $TARGET/js/ cp -r $TEMP/less/* $TARGET/less/   Not finding anything helpful on google, any idea what the problem is here? Reason for the current trend to use «she» as the gender-neutral pronoun? There are some questions on gender-neutral pronouns both  and on .  User Christine Letts :     In academia, there is currently a   movement toward using the feminine   pronoun at all times.   I wonder why that is. I came across several examples on papers I read, but the only one I can remember at the moment is a book: Seth Godin's . While some might not be comfortable labeling it as part of academia, it suits my point perfectly. Every time he refers to a person, he uses the feminine pronoun.  User Senseful  the following, potentially identifying affirmative action as the precursor for this trend.     I remember reading somewhere that it   was recommended to use the opposite of   what most people stereotype the   profession as. So, for example, when   talking about a chiropractor, you   would use "her", and when talking   about a secretary, you would use   "his".   So, where do you think this trend comes from? How to remove app icons in system tray on Ubuntu 18.04 with GNOME How can I remove the apps in right top corner (Google Chrome, flux, TeamViewer)?  Before my update from Ubuntu GNOME 16 these were even more annoying in the left down corner. Why couldn't River Song's memories bring back The Doctor in the rebooted universe? In the season 5 finale of Doctor Who, in the wedding ceremony of Amy, River Song showed up outside the door. Moments later, we discovered that she gifted Amy her blank diary which was supposed to contain information about The Doctor. It means River Song remembered The Doctor.  Memories of The Doctor was able to bring The Doctor back to existence in the rebooted Spacetime. Why couldn't River Song's memories work? Yesterday I had 3,606 reputation but today I have 3,592.  My profile shows that I lost 6 reputation when a user was removed, but that would put me on 3,600 - 8 reputation has magically disappeared.  Adding up all of my reputation does work out at 3,591 (I'm assuming by default new users have 1 rep, so that would make sense).  Somewhere a reputation change since yesterday isn't being displayed. I don't know what this would be for, but -8 would lead me to believe that someone removed their up-vote on an answer I'd posted which already had a down-vote (could it be from that deleted user?).  I don't know if this is a bug or if there is simply a delay between reputation updating, but I figured it was worth reporting.    Sadly I cannot prove that I had 3,606 reputation yesterday. I'm trying to simulate a media key press using a custom shortcut.  So far, I've been able to achieve the simulation I need using the command:  xdotool key XF86AudioPlay   It works perfectly, it pauses or starts the music player every time it is run.  The problem comes when trying to run it as a shortcut.  First I tried to run an alias with a custom shortcut, but it did not work.  As explained on :     The commands run by keyboard bindings are not parsed via a shell. Your best bet is to create a directory bin in your homedir.   Next I created the suggested script and named it simplay:  #!/bin/sh xdotool key XF86AudioPlay   It is located inside a bin folder which is part of the PATH, this works fine and can be run from any location.  When trying to create the Custom Shortcut, I was unable to get it to execute, the configuration is the following:  Name: test Command: simplay  Shortcut: Ctrl+Alt+R   After searching a bit more I found another way to execute the shortcut:  gnome-terminal -e simplay   I tried it on a terminal and noticed that when executing it it would rapidly open a new terminal window, execute the child process, pausing the music and immediately close the window.  I changed the command on the shortcut and when hitting it I noticed the same behavior opening a terminal and immediately being closed but this time the child process did not pause the music, which makes me think that the script has been called on all my previous attempts but it is somehow not being able to execute.  How can I solve this problem according to your knowledge? Remember last selected items per page in global search How to create a Gant-Chart in LaTeX-Beamer I am trying to create a Gant-Chart in Beamer. I found the following example:   \documentclass{beamer}  \usepackage[utf8]{inputenc} \usepackage{pgfgantt}  \title{Sample title} \author{Anonymous} \institute{Overleaf} \date{2019}   \begin{document}  \frame{\titlepage} \begin{frame}{Gant-Chart}     \begin{ganttchart}[vgrid, hgrid,                         bar/.append style={fill=blue!80},                        milestone/.append style={fill=green}]{1}{15}         \gantttitle{2019}{15} \\         \gantttitlelist{1,...,15}{1} \\         \ganttbar{Task 1}{1}{2} \\         \ganttmilestone{Milestone}{7} \ganttnewline         \ganttbar{Final Task}{8}{12}     \end{ganttchart} \end{frame}    \end{document}   Now, I want to change it slightly. The first row shows the year. I want the second row to show months. And then the third row shows the number of weeks that I have planned for the task. Also, I don't want to see any arrows, but just have the rectangles. Is there a way to add a grid? Basically I want everything to just look as in an Excel-Table: Grids and then color the rectangles during which I am working.   Here is an example of what I would like to have:   Can somebody show me how to do this?   Here is another example that seems to get pretty close to what I want. Only in the week-row now it is always written "week 1", "week 2" and so on. I just want the number.   \begin{frame} \begin{figure}[h!bt]     \begin{center}         \begin{ganttchart}[             vgrid={*{6}{draw=none}, dotted},             x unit=.08cm,             y unit title=.6cm,             y unit chart=.6cm,             time slot format=isodate,             time slot format/start date=2019-02-01]{2019-02-01}{2019-07-31}             \ganttset{bar height=.6}             \gantttitlecalendar{year, month=name, week} \\             \ganttbar[bar/.append style={fill=blue}]{Task 1}{2019-02-11}{2019-02-17}\\         \end{ganttchart}     \end{center}     \caption{Time Plan} \end{figure} \end{frame} Turning water pump on/off using Arduino Uno R3 I'm trying to build a simple system to turn a water pump every 24 hours for 10-20 seconds. I have 5V pump. When I connect it to 5V, GND it works but when I connect it to pin 12 (or any other digital pin) and GND it does not work. Here's my sample sketch:  int led = 12;  void setup() {                   Serial.begin(9600);   pinMode(led, OUTPUT);      }  void loop() {   digitalWrite(led, HIGH); }   What am I doing wrong? Over the time I've been able to vote for closure on SO, I've gotten into the habit of clicking on the reason itself in order to select the radio button corresponding to it. Since the reasons have changed, there are also now links in the middle of the text, which I also happen to accidentally keep clicking on. More annoyingly, these links don't open in a new tab so I have to click back and redo it. This happens most often with the "FAQ" link in the off-topic dialog, which is right there in the top left corner where I normally click.        Basically, those pieces of text now have two functions. One function of it is selecting the corresponding radio button and the other function is loading a new page. Obviously loading the new page trumps simple selection.  This has become even more painful now with the new off-topic messages, where a large portion of the message is a link:        A simple feature request: can the vote-to-close dialog itself not render the links? I have Google Chrome Version 70.0.3538.77 (Official Build) (64-bit).  Today, after running sudo apt update and sudo apt full-upgrade, I saw:  E: Repository 'http://dl.google.com/linux/chrome/deb stable Release' changed its 'Origin' value from 'Google, Inc.' to 'Google LLC' N: This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details.   I looked at the man page for apt-secure but it's pretty technical and difficult, at least for me, to follow.  So how do I fix this issue?    Edit: for now, I've removed the existing Google Chrome ppa from Software Sources and then ran sudo apt update and sudo apt full-upgrade successfully with the following being installed/upgraded successfully:  The following NEW packages will be installed:   python3-netifaces The following packages will be upgraded:   netplan.io nplan ppp 3 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. UK visa refusal For PLAB 2 I had applied for a visit visa (business) to appear for my PLAB 2 exam on 21 June 2019. I had to attend practice classes from an academy in Manchester for which I had attached the invitation letter; my duration was 15 days to prepare my exam in a better way. I had mentioned the cost of my trip to be £1500 and my brother sponsoring me for £3000 (my entire trip).   My rejection letter stated that I was going with my mother, when I had nowhere in my form or cover letter mentioned that I am going with my mother, because I was going alone. I had shown that my brother is my financial sponsor as I didnt have enough funds in my account. I had attested all the documents of my brother but somewhere in my form I made a mistake where I wrote the total money I have is £3000, but I had only £1200 in my account. I thought we had to write the total amount, so I put my brother's sponsor money, which was supposed to be £3000; he hadn't transferred it into my account, it was in his account only.  I made one more mistake in the form where they asked how much is the cost of travel to you personally. I wrote £1500 but I think I had to write nil there.   I don't know how to proceed now. Should I transfer £3000 into my account from my brother's account and get a bank statement proving the source of income? I don't have enough money in my account despite bring employed since Nov 2018 with a salary of £700 per month, as I had to make some big transactions such as booking my PLAB 2 exam (£830£), etc.  I have already booked the exam for £830 and I don't have much time left. Why is my host name wrong at the Terminal prompt when connected to a public WiFi network? For three days straight, I have connected to the public WiFi network at my local library. Each day, I have seen a different prompt in Terminal. Here are some of the prompts I've seen:  zp-pc:~ russell$ mary-pc:~ russell$ normob05:~ russell$   I have check under System Preferences -> Sharing, and my computer name is "Russell's Mac". Also, I set the DHCP Client ID to "RUSSMAC" under System Preferences -> Network -> Advanced -> TCP/IP, but I still see the random host names at the Terminal prompt.  Why is my computer name changing every day? Validate that string contains only allowed characters in Ruby In HLW8012 where should I connect the reference voltage (GND) In the , the both 33nF capacitors , 1K resistor and 0.1uF capacitor are connected to GND. I'm not sure where should I connect those ends of components marked with GND symbol, (To Live, To Natural or the DC GND). I can't read Chinese, I don't really know what everything mean there.  Live directly connects to the shunt resistor and this means that live is also GND (0 volt reference) for the chip? Should I connect those end of components marked as GND symbol to Live wire? How to analyze trend in non-periodic time series Suppose I have following non-periodic time series. Obviously the trend is decreasing and I would like to prove it by some test (with p-value). I am unable to use classic linear regression due to strong temporal (serial) auto-correlation among values.  library(forecast) my.ts &lt;- ts(c(10,11,11.5,10,10.1,9,11,10,8,9,9,                6,5,5,4,3,3,2,1,2,4,4,2,1,1,0.5,1),             start = 1, end = 27,frequency = 1) plot(my.ts, col = "black", type = "p",      pch = 20, cex = 1.2, ylim = c(0,13)) # line of moving averages  lines(ma(my.ts,3),col="red", lty = 2, lwd = 2)     What are my options?