What do these symbols "$@">/dev/null 2>&1" after a command mean?
What does outputting to /dev/null accomplish in bash scripts?
How to install pip for python 3 in ubuntu 12.04 LTS Why are "baked" and "naked" not pronounced the same? How to get from Gatwick airport to Paddington? What's the most straightforward way to get from Gatwick airport to Paddington station in London using public transport?   I'm mostly interested in travel time &amp; general smoothness of the trip (e.g. buying just one ticket for the whole trip would be nice). Price is a secondary concern. Adjectives or compound noun? Strange character when using listings package I'm seeing an odd character like a very flat U, where there should be a space, with the listings package. See example below. Does anyone have any idea why this is happening, or how to get rid or work around it?  \documentclass{standalone} \usepackage{underscore} \usepackage{listings} \usepackage[usenames,dvipsnames, rgb, svgnames, x11names]{xcolor} % Text layout \topmargin 0.0cm \oddsidemargin 0.5cm \evensidemargin 0.5cm \textwidth 16cm \textheight 21cm  \lstnewenvironment{cmd}[1][]{%   \lstset{language=sh, backgroundcolor=\color{LightSteelBlue1}, #1}} {}  \begin{document} \begin{cmd}[caption=Configuration file section including filters] [affy6] [...]     [[hapmap]]     phenofiles = "data/Hapmap6.0/Pheno/hapmappheno_909.csv",     genofile = "/data/snppy/Hapmap6.0/Geno/birdseed-v2.calls.txt"     anno_filter = "chromosome = 5"     idlink_filter = "studyid = 'CEU'"     some_other_stuff = "foo = bar" \end{cmd} \end{document} this works in viewport but not in render.  import bpy from math import *  def frame_handler(scene):     z = scene.objects['Lift'].location[2]     scene.objects['Text'].data.body = str(floor(z / 4.0) - 2)  bpy.app.handlers.frame_change_pre.clear() bpy.app.handlers.frame_change_pre.append(frame_handler)   How to get it working in render? I've read  and changed from "bpy.data.objects" to "scene.objects" as already seen in the script. What am I missing? Blender v. 2.81.16  Edit. Tried that depsgraph thing mentioned in comments and changed to frame_change_post:  import bpy from bpy.app.handlers import persistent from math import *  @persistent  # maybe not relevant but doesn't harm anything? def frame_handler(scene, depsgraph):     z = scene.objects['Lift'].evaluated_get(depsgraph).location[2]     scene.objects['Text'].data.body = str(floor(z / 4.0) - 2)  bpy.app.handlers.frame_change_pre.clear() bpy.app.handlers.frame_change_post.clear() bpy.app.handlers.frame_change_post.append(frame_handler)   Now the Text doesn't show up at all in rendered (but works in viewport). addtocontents not working with certain other packages Given that $x^y=y^x$, what could $x$ and $y$ be? It's not too difficult to figure out that $x$ and $y$ can both be 1, and also $x$ can be 2 and $y$ can be 4 (and vice versa). But I can't rule out if there are other solutions. Does it have anything to do with inverse functions? Is there a way to see the solutions by graphing, or algebraically? I am currently writing an academic text and need to directly quote/cite text from a paper. What is best practice when I need to add a remark/note to the quote?  For instance, I would do it like this: The authors claim that "we do the best work ever in the area of CS (note: Computer Science)".  So in the above case the actually quoted text is "we do the best work ever in the area of CS", however, I want to add a note which explains the abbreviation "CS".  How should this be done?  Related questions: Validationengine jquery not working properly for localization What happens if my shield breaks? Performance differences between pipelines and process substitution I tend to use pipelines in my bash scripts over process substitution in most situations, especially in cases of using multiple sets of commands as it seems more readable to do ... | ... | ... over ... &lt; &lt;(... &lt; &lt;(...)).  I'm wondering though why using process substitution is much faster in some situations than using a pipeline.  To test this, I timed two scripts using 10000 iterations of the same attached commands with one using a pipeline and another using process substitution.  Scripts:  pipeline.bash:  for i in {1..10000}; do     echo foo bar |     while read; do         echo $REPLY &gt;/dev/null     done done   proc-sub.bash  for i in {1..10000}; do     while read; do         echo $REPLY &gt;/dev/null     done &lt; &lt;(echo foo bar) done   Results:  ~$ time ./pipeline.bash  real    0m17.678s user    0m14.666s sys     0m14.807s  ~$ time ./proc-sub.bash  real    0m8.479s user    0m4.649s sys     0m6.358s   I know that pipelines create a sub process whereas process substitution creates a named pipe or some file in /dev/fd, but am unclear about how those differences impact performance. Java Enum definition Show that unit circle is not homeomorphic to the real line Showing that $\gamma = -\int_0^{\infty} e^{-t} \log t \,dt$, where $\gamma$ is the Euler-Mascheroni constant. I'm trying to show that  $$\lim_{n \to \infty} \left[\sum_{k=1}^{n} \frac{1}{k} - \log n\right] = -\int_0^{\infty} e^{-t} \log t \,dt.$$  In other words, I'm trying to show that the above definitions of the Euler-Mascheroni constant $\gamma$ are equivalent.  In another post here (which I can't seem to find now) someone noted that  $$\int_0^{\infty} e^{-t} \log t \,dt = \left.\frac{d}{dx} \int_0^{\infty} t^x e^{-t} \,dt \right|_{x=0} = \Gamma&#39;(1) = \psi(1),$$  where $\psi$ is the digamma function.  This may be a good place to start on the right-hand side.  For the left-hand side I was tempted to represent the terms with integrals.  It is not hard to show that  $$\sum_{k=1}^{n} \frac{1}{k} = \int_0^1 \frac{1-x^n}{1-x} \,dx,$$  but I'm not sure this gets us anywhere.  Any help would be greatly appreciated. Sign of determinant when using $det A^\top A$ We have been given matrix: $$A =          \begin{pmatrix}         a&amp; b&amp; c &amp;d \\         b &amp;−a&amp; d&amp; −c\\         c&amp; −d &amp;−a&amp; b \\         d &amp;c&amp; −b&amp; −a\\         \end{pmatrix}     $$ ...and have been asked to calculate $\det(A)$ using $AA^T$.  We see that:  $$AA^T=\begin{pmatrix}         a^2+ b^2+ c^2+ d^2&amp; 0&amp; 0&amp;0\\         0 &amp;a^2+ b^2+ c^2+ d^2&amp; 0&amp; 0\\         0&amp; 0 &amp;a^2+ b^2+ c^2+ d^2&amp; b \\        0 &amp;0&amp; 0&amp; a^2+ b^2+ c^2+ d^2\\         \end{pmatrix}     $$   So, $\det(AA^T)= (a^2+ b^2+ c^2+ d^2)^4$  Now which should I choose: $(a^2+ b^2+ c^2+ d^2)^2 $ or $ -(a^2+ b^2+ c^2+ d^2)^2$ ?  Please explain me which one and why. Linear congruence fill in the missing step? Currently working on this problem and I'm having trouble seeing how it goes from one line to the next.    $45x \equiv 63\mod 11$ goes to $x \equiv 8\mod 11$     Any help would be awesome thanks.  Please try to explain how it works to help me see thanks. Converting from 7-speed to 10-speed rear wheel My Bridgestone MB-5 currently has a 7-speed rear wheel. I'd like to convert it to a 10-speed. Is this possible? Is it practical? How to return value from an asynchronous callback function? I took some shots recently and I noticed that I'm getting a lot of little black dots in my images.  I cleaned my lens thoroughly with the Nikon camelhair brush and retook the pictures but once again, the dots appear.  I'm shooting with a Nikon D7000 and using a starter lens. I've attached an example (notice the black spots on the chairs, on the ceiling, etc).