I'm cleaning up my MBP and found two Library folders, one of 3.37 Gb and the other 9.75 Gb. Why are there two of them, and more importantly, how can I reduce their sizes?
There are two 'Library' directories in my OS X 10.11 installation, one being /Library/, the other being /System/Library/. What is the difference between different Library folders?
best practices for organizing digital and physical articles As a thirsty graduate student, I've amassed a burgeoning collection of research articles in both paper and digital formats. Right now I manage pdfs and references with Zotero, but I'm still searching for an organization logic for paper documents that allows rapid access and prevents redundant printing and storage.  have suggested organizing by topic, while another approach is to sort by author name. Topical organization has not worked well for me in the past because my research is highly interdisciplinary, confounding my categorization efforts. For a coupled digital-physical organization system I'm considering the following:   Digital documents and references stored and tagged in Zotero Indicator in Zotero whether or not I've printed in the file Physical documents stored in manila file folders labelled alphabetically   What is the most effective way that you've found to maintain both paper and digital document repositories? Recommended way to initialize srand? When to Garbage Collect Unable to install "": snap "" has "install-snap" change in progress I have a chromebook series 5. I want to install Ubuntu onto a USB stick. When I downloaded Ubuntu onto my USB stick, it won't start up.  Do I first have to download Ubuntu onto my chromebook hard drive, open Ubuntu and then make USB stick bootable? And then return back to chrome?  Or is there a way to download directly onto USB and make the stick bootable?  I appreciate any help. Prove that $g$ is tangent to the graph of $f$ Prefer composition over inheritance? If $\sum (a_n)^2$ converges and $\sum (b_n)^2$ converges, does $\sum (a_n)(b_n)$ converge? If $\sum (a_n)^2$ converges and $\sum (b_n)^2$ converges, does $\sum (a_n)(b_n)$ converge?  Could someone help me to solve this or at least give me a hint?, I have tried using Cauchy's criterion, the Dirichlet test for convergence, etc, but I can´t prove it.Honestly I don´t know where to start. Any help will be appreciated. Mean, Average and Expectation What is the precise difference between the Mean, Average and Expectation ? Is there any mathematical formaulation to show the difference ? I see that often they are used interchangeably. Let $R$ be a commutative ring.  The nilradical $\text{nil}(R)$ is the set of all nilpotent elements, and it is the intersection of all the prime ideals of $R$.  Is the following true in the polynomial ring? $$\text{nil}(R[X])=(\text{nil}(R))[X]$$  Any polynomial in the right hand side has all its coefficients nilpotent in $R$, hence also in $R[X]$, and therefore it is nilpotent in $R[X]$ as the sum of nilpotent elements.  The other inclusion is not clear to me.  Is there a counterexample? consider positive numbers $a_1,a_2,a_3,\ldots,a_n$ and $b_1,b_2,\ldots,b_n$. does the following in-equality holds and if it does then how to prove it  $\left[(a_1+b_1)(a_2+b_2)\cdots(a_n+b_n)\right]^{1/n}\ge \left(a_1a_2\cdots a_n\right)^{1/n}+\left(b_1b_2\cdots b_n\right)^{1/n}$ Suppose $k$ is a field, $A$ is a $k$-subalgebra of the polynomial ring $k[x]$. Must $A$ be a finitely generated $k$-algebra?   Thanks. The Canon L lenses are much more expensive and presumably much better quality than non-L lenses. What makes an "L" lens? How much better are they over a similar length/speed "ordinary" canon lenses? Why is my variable local in one 'while read' loop, but not in another seemingly similar loop? Why do I get different values for $x from the snippets below?  #!/bin/bash  x=1 echo fred &gt; junk ; while read var ; do x=55 ; done &lt; junk echo x=$x  #    x=55 .. I'd expect this result  x=1 cat junk | while read var ; do x=55 ; done echo x=$x  #    x=1 .. but why?  x=1 echo fred | while read var ; do x=55 ; done echo x=$x  #    x=1  .. but why? iOS 11-13 - unable to paste into comments I’m able to copy-paste from any application to any application. I’m able to copy from a comment or from a question or from an answer. I’m able to paste to a question or answer. However, if I attempt to paste into a comment, nothing happens. I am able to subsequently paste into another application, confirming that the text is actually on the clipboard.   However, copying SE links will paste them successfully, but all other text - including other links - still fails. This leads me to believe that it’s a SE issue and not an Apple one.   This has been an issue since 11.0 beta and persists through iOS 13 release. How to avoid messages from applications which I ran with a &? I ran dolphin like this:  dolphin . &amp;   I see messages in the console like these:  QPixmap::scaled: Pixmap is a null pixmap   How can I keep the console clean or silent? Is it possible to have 2 git repositories in one directory?  I'd think not, but thought I'd ask.  Basically, I'd like to check in my home directory config files (e.g. .emacs) which should be common across all of the machines I work on, but have a second repository for local files (e.g. .emacs.local), which contains machine-specific configurations.  The only way I can think of to do that is to have the local config in a subdirectory and ignore that subdirectory from the main git repository.  Any other ideas? Dimensions of symmetric and skew-symmetric matrices Does not the mass of those living on the Earth add on to the mass of the Earth or is it too negligible to be cared for? : Earth weighs about 13,170,000,000,000,000,000,000,000 pounds (or   5,974,000,000,000,000,000,000,000 kilograms). Since Earth is too big   to be placed on a scale, scientists use mathematics and the laws of   gravity to figure out Earth's weight.   So, this seems to be a constant. But I guess it doesn't consider the things that are on the earth, the trees, buildings, people, animals, water etc...  So, are all the above mentioned things' mass is too small or negligible to be left off? Can I travel to Germany from a country different from the one I got the visa from?