In bash  echo {{a,b}.{c,d}}  expands to  {a.c} {a.d} {b.c} {b.d}  Though nothing is mentioned for brace expansion in bash manual for the type of input I have made   My question is why the output is not like this a.c  a.d  b.c  b.d
I was trying to concatenate text files in sub-folders and tried:  cat ./{mainfolder1,mainfolder2,mainfolder3}/{subfolder1}/book.txt &gt; out$var   However this did not return anything. So, tried adding a non existing 'subfolder2'  cat ./{mainfolder1,mainfolder2,mainfolder3}/{subfolder1,subfolder2}/book.txt &gt; out$var   And this time it did work out, concatenating the files successfully. Why does this happens?
Using find with grep, one can locate files that match a pattern:  # find | grep error ./solr-modifiedSolr4/SolrPhpClient/phpdocs/errors.html ./error_log ./includes/classes/error_log   However, using find alone the first file is not found:  # find . -name error* ./error_log ./includes/classes/error_log   Why doesn't find locate the errors.html file when not used with grep? How is find used to show this file as well? How can I completely remove a objects (e.g. particle system or groups used in particle systems) in blender using python?  The problem is this: I have a script, with which I create a scene (e.g. adding some normal objects and some group of objects with a particle system). For a research study I would like to repeat that that several times, without restarting blender. So I can create a scene, delete everything, e.g. with a script like this:  import bpy scn = bpy.context.scene for obj in scn.objects:     obj.select = True bpy.ops.object.delete()   If I rerun the script to recreate the scene with objects using particle system, the latter is not shown in the scene anymore (only the placeholders of the particle system). Now I'm not sure where exactly the problem lies, but I guess not everything is immediately deleted, running the script above. Only the startup of blender helps (but that's not what I want) or pushing the purge button. The purge button seems to start the command:  bpy.ops.outliner.orphans_purge()   But I can't get this piece of code to run in the console. It says that "the context is incorrect". Is there a way to purge the unused data by python script? Thanks a lot for any help. I'm having some trouble proving the following statement using mathematical induction:   $$\frac{1}{2}n^{\frac{3}{2}} \leq \sqrt{1} + \sqrt{2} + \sqrt{3} + \sqrt{4} + ... + \sqrt{n}      ,\text{ (for all sufficiently large n)}$$   I'm sort of confused because $n^{\frac{3}{2}}$ = $n  n^{\frac{1}{2}}$ which means that there are n of the largest possible root values on the left hand side while the right hand side has values like $\sqrt{1}$, $\sqrt{2}$, etc. As n grows sufficiently large wouldn't the left hand side outgrow the right hand side no matter what the constant multiple is? If I'm thinking about this correctly just let me know, if not, any help would be appreciated. When should end punctuation go inside quotes? I have been/am being taught that end punctuation should always go inside quotes. For example, you are supposed to write:     Marvin thought it was "awful."   The problem is I do not see how does this make sense. Intuitively, I always wrote:     Marvin thought it was "awful".   as that makes more logical sense — you want a quote to be an exact replication of what somebody else said, so why should you add punctuation inside?  I always thought it made more sense to not touch the quote and add anything after or before if it must be added.  So, why should I put end punctuation inside quotes? Why would Mystique's DNA allow for Sentinels that can duplicate mutant powers? The future Sentinels in  are clearly shown adapting to powers thrown at them by copying them. Isn't that what Rogue's DNA would allow for, not Mystique's? Mystique can just change appearance, not copy powers ... right? So why would study of her mutant genes allow for the abilities of the future Sentinels? What white point temperature should I set my LCD monitor to? I've got the Xrite Eye One Display 2, and tried the advanced calibration today for the first time.  It asked what white point I wanted, and had a default of 6500K.  I didn't realize that was up for discussion!  I would have assumed the daylight temperature, around 5500K, would be desired.  What temperature do I want my whites to be? Why can't white just be white?! Reading list in topological QFT Ubuntu 17.10 and later: can't change the input switching shortcut to alt+shift Alien invasion movie, giant robot aliens with long legs capturing people There are many lengths in LaTeX. For instance, \enskip, \enspace, \quad, \parskip, \smallskip, ...  Some of them are mostly used for vertical spacing, some others are mostly used for horizontal spacing, and perhaps some of them are used in both cases. I wonder whether there is a list that indicates the meaning and intended use of each length in LaTeX.  By "intended use" I mean not only whether the length is vertical or horizontal, but in which circumstances it is a good practice to use that specific length. How is offside determined in football? The offside rule on the pitch is often unclear and called suddenly. How do I know if a player is offside? In Bash, suppose I visit a directory, and then another directory. I would like to copy a file from the first directory to the second directory, but without specifying the long pathnames of them. Is it possible?   My temporary solution is to use /tmp as a temporary place to store a copy of the file. cp myfile /tmp when I am in the first directory, and then cp /tmp/myfile . when I am in the second directory. But I may check if the file will overwrite anything in /tmp.  Is there something similar to a clipboard for copying and pasting a file? "I am going to have a walk" My teacher said "I am going to have a walk" today in class and to me it seems incorrect. Correct variants that I know are:    Going for a walk Going to take a walk Going to walk  ...   Is this correct? If so, why? Elastic net penalty For instance if me and my friend had a Pidgeot and we powered them all the way up. Could mine end up with like 525 and his at like 500? What is the word that is used to describe the oversimplification or non-academic discussion of a complex issue?   Typically, I'm looking for a word like pedantic, or puerile, except that the word covers the fact that the discussion is particularly non-academic. I know that such a word exists since I have used it before, but it has skipped my mind. Where do Orc babies come from? I've not seen/read any female Orcs mentioned in the movies or in the books. In one of the movies, an Uruk-hai is momentarily shown emerging from a giant, grown-Orc sized flesh packet. So are they created with spells, or do they follow the Standard Reproductive Model. vim and system clipboard I can cat a file, copy and paste text with the middle button or shift-insert.  How can I copy text in vim and paste it from the system clipboard? How do I remove a file I accidentally created named $file? I was working on a shell script and I accidentally created a file with the variable as its name. Now I have $file in my ls output, and cannot remove it.  What can I do? Points at integer distance How many points can one can place in $\mathbb{R}^n$, with the requirement that no $n+1$ points lie in the same $\mathbb{R}^{n-1}$-plane, and the euclidean distance between every two points is an integer?