Why does this shell script:  $ curl -d "asd" 0.0.0.0/abc &amp; echo "abc";   results in me having to press enter before it enters the shell again. The curl is just a post request to a simple web server which returns abc.  However, this script does not require me to press enter before entering the shell again  $ echo "abc" &amp; echo "abc"
abhigenie92@ubuntu:~$ (sleep 2; echo $BASH_SUBSHELL ;sleep 2) 1 abhigenie92@ubuntu:~$ (sleep 2; echo $BASH_SUBSHELL ;sleep 2)&amp; [1] 3297 abhigenie92@ubuntu:~$ 1  [1]+  Done                    ( sleep 2; echo $BASH_SUBSHELL; sleep 2 )   What happens when launch it as a background process, why don't I get the prompt back and I have to press Enter? In both cases it launches a child shell.
Pressure variation in a sound wave Currently, a user does not get any notification when a trivial edit (less than 6 characters, by a user who has the ) is made on one of his/her posts. As in .  Even though the user is trust-worthy (owing to the rep of the user), wouldn't it be nice for the OP to get a notification whenever an edit is made, even trivial? I happen, time and again, to read and hear people – among which people working in cinema – regretting the fact that film (in the sense of actual reels of plastic strip) is nowadays very rarely used when shooting movies. Is there some ground to such nostalgia?  Of course I am not looking for opinions for or against film vs. digital media, but sourced, objective reasons. Is there anything that could be done with film but not with digital supports? Are there measurable differences in effects on viewers? So I defeated a Team Valor gym earlier today using my highest cp Pidgeot. It turned grey, so I went to claim it with that Pidgeot, except it wouldn't let me. What determines which pokemon you are allowed to place at a gym? Is it just those who have participated in a battle can't? Is there a time period for it? What about training at a friendly gym? Does this impact anything? which statistic should I use for inter-rater agreement on nominal data, multiple responses I have over 400 open-ended responses. The total has been coded by one rater, and a 10% identical sample of the total has been coded by 2 raters. There is a choice of 14 nominal codes, of which the rater can use any number per case, though most cases have between 1-4 codes. Which statistical test is the most appropriate to determine if I have inter-rater agreement on the 10% sample?   Also am I right in assuming that I will need to treat each code as a variable and look for the level of agreement for each variable?   I'm using SPSS 21.  Much thanks, Kellie Motivation for Kolmogorov distance between distributions There are many ways to measure how similar two probability distributions are.  Among methods which are popular (in different circles) are:   the Kolmogorov distance: the sup-distance between the distribution functions; the Kantorovich-Rubinstein distance: the maximum difference between the expectations w.r.t. the two distributions of functions with Lipschitz constant $1$, which also turns out to be the $L^1$ distance between the distribution functions; the bounded-Lipschitz distance: like the K-R distance but the functions are also required to have absolute value at most $1$.   These have different advantages and disadvantages.  Only convergence in the sense of 3. actually corresponds precisely to convergence in distribution; convergence in the sense of 1. or 2. is slightly stronger in general.  (In particular, if $X_n=\frac{1}{n}$ with probability $1$, then $X_n$ converges to $0$ in distribution, but not in the Kolmogorov distance. However, if the limit distribution is continuous then this pathology doesn't occur.)   From the perspective of elementary probability or measure theory, 1. is very natural because it compares the probabilities of being in some set. A more sophisticated probabilistic perspective, on the other hand, tends to focus more on expectations than probabilities. Also, from the perspective of functional analysis, distances like 2. or 3. based on duality with some function space are very appealing, because there is a large set of mathematical tools for working with such things.  However, my impression (correct me if I'm wrong!) is that in statistics, the Kolmogorov distance is the usually preferred way of measuring similarity of distributions.  I can guess one reason: if one of the distributions is discrete with finite support -- in particular, if it is the distribution of some real-world data -- then the Kolmogorov distance to a model distribution is easy to compute.  (The K-R distance would be slightly harder to compute, and the B-L distance would probably be impossible in practical terms.)  So my question (finally) is, are there other reasons, either practical or theoretical, to favor the Kolmogorov distance (or some other distance) for statistical purposes? Exposing database IDs - security risk? I've heard that exposing database IDs (in URLs, for example) is a security risk, but I'm having trouble understanding why.  Any opinions or links on why it's a risk, or why it isn't?  EDIT: of course the access is scoped, e.g. if you can't see resource foo?id=123 you'll get an error page. Otherwise the URL itself should be secret.  EDIT: if the URL is secret, it will probably contain a generated token that has a limited lifetime, e.g. valid for 1 hour and can only be used once.  EDIT (months later): my current preferred practice for this is to use UUIDS for IDs and expose them. If I'm using sequential numbers (usually for performance on some DBs) as IDs I like generating a UUID token for each entry as an alternate key, and expose that. Why do objects in front and back view look reversed? Whenever I model objects that has different look at front and back. Viewing it from front perspective or orthographic the model displays back of the object. Error in batch file to copy folder: 'Invalid number of parameters' I am making a batch file in Windows XP to copy my folders I need to another folder on my PC. I am getting an error.  I get the error "Invalid number of parameters".  xcopy /s/z D:\Documents and Settings\%username%\Desktop C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\Favorites C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\Start Menu C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\My Documents C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\PrintHood C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\NetHood C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\Templates C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\Searches C:\SomeRandomFolder\ xcopy /s/z D:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook C:\SomeRandomFolder\ pause   Then I changed the batch and get this error: "File not found - Desktop"   xcopy /s/z D:\...\%username%\Desktop C:\SomeRandomFolder\ pause   How do I fix these errors? How do I get my Python program to sleep for 50 milliseconds? I'm using pdfLatex (with --shell-escape option) and I had a problem of compilation with TexWorks that was successfully solved with the help of other post in this site: .  After correcting that error the code compiles smoothly but just displays the logarithmic grids, not the function. The gnuplot files are created in the right place, but the graphic doesn't come out in the PDF.  Code from :  \documentclass{article}  \usepackage{tikz} \usepackage{bodegraph}  \begin{document}  \begin{tikzpicture}[     gnuplot def/.append style={prefix={}}, % Fixed the issue (prefix was 'gnuplot/\jobname/' before) ] \begin{scope} \UnitedB \semilog{-1}{2}{-50}{60}  \BodeAmp{-1:1.35}{\POAmpAsymp{4}{2.0}+\IntAmp{1}}  \end{scope} \end{tikzpicture} \end{document}   Any clues? Background image resize in Ubuntu 18.04.1 LTS Recently updated to 18.04.1 and now I cannot resize my background image from fill screen to center image.  How can I resize the image now that 18 doesnt have the quick resize feature? Is a Cauchy sequence - preserving (continuous) function is (uniformly) continuous? Let $(X,d)$ and $(Y,\rho)$ be metric spaces and $f:X\to Y$ be a function and suppose for any Cauchy sequence $(a_n)$ in $X$, $(f(a_n))$ is a Cauchy sequence in $Y$.  Is $f$ continuous?  Let $f$ be continuous, is it uniformly continuous? Align multiple numbered aligned blocks There are many discussions over how to align multiple align environments with interspersed texts. However, I want to label multiple aligned blocks such that each number will center vertically for each aligned blocks and at the same time align across blocks.  Here is a MWE that achieves either at one time. The first part simply uses one giant align environment with some \nonumber directive. The second one use equation to wrap aligned but lose alignment info. How should I achieve the best of both worlds?  \documentclass{article} \usepackage{amsmath} \begin{document}   % Part I   \begin{align}           x^2 + y^2 &amp;= 1 \\                 z^2 &amp;= 0 \nonumber \\     x^2 + y^2 + z^2 &amp;= 1   \end{align}    % Part II   \begin{equation}     \begin{aligned}       x^2 + y^2 &amp;= 1 \\             z^2 &amp;= 0 \\     \end{aligned}   \end{equation}   \begin{equation}     \begin{aligned}       x^2 + y^2 + z^2 &amp;= 1     \end{aligned}   \end{equation} \end{document} My disk already has 4 primary partitions, how can I install Ubuntu? newcommand vs. DeclareMathOperator As far as I understand, whatever can be done using DeclareMathOperator can also be achieved using newcommand, but not the other way around. If this is the case, what are the circumstances where DeclareMathOperator is the better choice? When should I take solely newcommand?  I found a question regarding , and I wonder what other aspects should be taken into consideration when it comes to choosing which method to use when defining math operators. PrintWriter append method not appending How do I change my default browser? Is there an option to change my default browser for all my applications? Does it make any difference for SEO benefits to buy dropped and already available domains other than backorder domains that are expiring soon?  I heard somewhere that whois gets deleted after being dropped. But I didn't find any confirmation if it's true or not.  Anybody can tell me if there are benefits of one against the other, if yes what? $A \cup B$ and $A \cap B$ connected $\implies A$ and $B$ are connected Let $X$ be a topological space. Let $A$ and $B$ be two subsets of $X$ such that: $A$ and $B$ are closed, $A \cup B$ is connected, $A \cap B$ is connected     Prove that $A$ and $B$ are connected.   Thoughts:  Suppose that $A$ is disconnected. Since $A$ is closed, there are two non-empty, disjoint, closed sets $E$ and $F$ in $X$ such that $A = E \cup F$. Then I attempted many things but all were not really useful.  Please help. Thanks.