I need to setup a big hard disk (4TB) so that I'll be able to use it in both macOS and in a Raspberry Pi.  Up to now all my attempts failed - at the moment I have formatted it so that it uses GPT, type "linux filesystem", and all the 4TB are recognized - linux recognizes it but not the Mac  The solution proposed in  does not work since it suggests the MSDOS type, which doesn't work for big disks.  Is there a recommended way to solve this?
I have a USB drive that I can see/access/modify/etc in Linux/Ubuntu but it doesn't show up on my Mac OSX.  I did sudo fdisk /dev/sdb (where my USB is) and then g to create a new GPT partition table, n to make a new partition, used all default settings, then w to save and exit.  Then I did sudo mkfs.fat -F32 /dev/sdb1 to format the partition with a FAT32 filesystem.  I ejected the USB and put it in my Mac and it doesn't show up / get detected.  What did I miss?
How to process a multi column text file to get another multi column text file? I have a text file:  a   aa  aaa     b   bb  bbb     c   cc  ccc d   dd  ddd     e   ee  eee     f   ff  fff g   gg  ggg     h   hh  hhh     i   ii  iii j   jj  jjj   How can I process it and get a 2 column file like this:  a   aa aaa b bb  bbb c   cc ccc d dd  ddd e   ee eee f ff  fff g   gg ggg h hh  hhh i   ii iii j jj  jjj   Or a three column file like this:  a   aa  aaa b   bb  bbb c   cc  ccc d   dd  ddd e   ee  eee f   ff  fff g   gg  ggg h   hh  hhh i   ii  iii j   jj  jj   I prefer to get awk solution but other solutions are welcomed too. What do the fields in ls -al output mean? Totally ordering the power set of a well ordered set. Let's say I take a set $S$, where $S$ can be well ordered. From what I understand, one can use that well ordering to totally order $\mathscr{P}(S)$.  How does a body actually use the well ordering of $S$ to construct a total ordering of $\mathscr{P}(S)$?  Perhaps construct is too strong a word. Is there a way to prove that a total ordering of $\mathscr{P}(S)$ just exists, no need to explicitly state what it is, since that might be very difficult. Using Xpath With Default Namespace in C# I've got an XML document with a default namespace. I'm using a XPathNavigator to select a set of nodes using Xpath as follows:     XmlElement myXML = ...;   XPathNavigator navigator = myXML.CreateNavigator(); XPathNodeIterator result = navigator.Select("/outerelement/innerelement");   I am not getting any results back: I'm assuming this is because I am not specifying the namespace. How can I include the namespace in my select? Imagine this directory structure:  app/    __init__.py    sub1/       __init__.py       mod1.py    sub2/       __init__.py       mod2.py   I'm coding mod1, and I need to import something from mod2. How should I do it?    I tried from ..sub2 import mod2 but I'm getting an "Attempted relative import in non-package".  I googled around but found only "sys.path manipulation" hacks. Isn't there a clean way?      Edit: all my __init__.py's are currently empty    Edit2: I'm trying to do this because sub2 contains classes that are shared across sub packages (sub1, subX, etc.).  Edit3: The behaviour I'm looking for is the same as described in  (thanks John B) How can I take a picture with my webcam in Windows 7? I know it existed as sort of a folder in Windows Explorer in at least Windows XP, but I just can't seem to find it in Windows 7...  How can I take a picture with my webcam in Windows 7 without using any 3rd party tools? Expansion of $(1+px+qx^2)^8\equiv 1+8x+52x^2+kx^3$... $(1+px+qx^2)^8 \equiv  1+8x+52x^2+kx^3...$  Given that expression, calculate the values of p, q, and k.  I'm guessing this is a trinomial that needs to be turned into a binomial, but how would you do it? I have no idea. Can you benefit from the Dueling fighting style for one weapon, then draw a second weapon as part of Extra Attack to qualify for Two-Weapon Fighting? Find the subgroups of A4 I had a question I was hoping for some help on:     Find all of the subgroups of $A_4$   Here is what I know:  $A_4$ is the alternating group on 4 letters. That is it is the set of all even permutations. The elements are:  $(1), (12)(34), (13)(24), (14)(23), (123), (132), (124), (142), (134), (143), (234), (243)$   which totals to 12 elements. Which means, the subgroups should have order 1,2,3,4,6 and 12. The groups of order 1 and order 12 are trivial. I also know the groups of order 2 which are:  $[1,(12)(34)], [1, (13)(24)], [1, (14)(23)]$  but would someone be able to help me find the subgroups of order 3, 4 and 6 and be able to provide a good, easy explanation of how you got to them for me? I'm pretty sure there is no such groups of order 6, but I don't know how to explain why.  Thank you so much for your help in advance, I really appreciate it! A sci-fi book or TV show about a tribesman discovering he or she actually lives in a huge spaceship The story starts with a tribesman going on a exploratory voyage around the land, meeting other progressively more and more distant tribes, learning about the world. Gradually he or she discovers that the "world" is actually a giant spaceship flying through space.  The story climaxes by the hero ascending to the commanding deck and learning who actually pilots the ship and to what purpose. I've read and have heard of both 'as per' and 'per' being used conversationally, both with the same connotation of either 'according to' or 'on authority of'  Examples:  "Tell Ron to start molding new rollers for the mecanum wheels, as per me"  "Per Mr. Crane, you need to start the molds for the new rollers."  They both establish the same context by setting that something should be done on the authority of someone else (or the speaker, per the first example (see what I did there?)). Or it acts as a way to cite a source of a statement, directive or fact in conversational speech.  My question is, what is, if any, the functional and syntactical difference between as per and per. If there are no differences, which is apropos to use? Suppose I have a python object x and a string s, how do I set the attribute s on x? So:  &gt;&gt;&gt; x = SomeObject() &gt;&gt;&gt; attr = 'myAttr' &gt;&gt;&gt; # magic goes here &gt;&gt;&gt; x.myAttr 'magic'   What's the magic? The goal of this, incidentally, is to cache calls to x.__getattr__(). When to use an interface instead of an abstract class and vice versa? This may be a generic OOP question. I wanted to do a generic comparison between an interface and an abstract class on the basis of their usage.   When would one want to use an interface and when would one want to use an abstract class? PGFPlots: Understanding how to draw plots on different layers and arrange them Why is electric field lines away from (+) and toward (-)? I have a questions about the electric field lines.   Well in the basic learning, we know that:   The electric field lines extend away from a positive charge They move forward a negative charge   Let's take parallel plates, which make a uniform electric field.If we take the basic learning, which I mentioned, in accounts, it's very easy to understand that this is the direction of a positive charge object if we put the object between the plate (move away the positive charged plate and toward negatively charged plate).  The problem is if we put a negative charged object between. Isn't the electric field reversed ? I have this function $$f(x) = x\cos(1/x)$$ defined for all $x \geq 1$.      How do I prove that    $$f(x+2)-f(x)&gt;2$$    for all $x\geq 1$?   I found $$f'(x)= \cos(1/x) + \frac{\sin(1/x)}{x}$$ and $$f''(x)=-\frac{\cos(1/x)}{x^3}.$$ How do i use this information? Without appealing to the axiom of choice, it can be shown that (Proposition:) if $X$ is well-orderable, then $2^X$ is totally-orderable.  Question: can we show the stronger result that if $X$ is well-orderable, then so too is $2^X$?  Proof of Proposition. Pick any well-ordering of $X$. Then the lexicographic order totally orders $2^X$.  More explicitly: for any two $f,g \in 2^X$, define $f &lt; g$ iff   there exists $x \in X$ such that $f(x) \neq g(x)$, and if $x \in X$ is minimal such that $f(x) \neq g(x)$, then $f(x)=0$ and $g(x)=1$.   It can be shown that $&lt;$ totally-orders $2^X$. Potential energy of an infinitesimal length of elastic rod Integrate $\int_{0}^{2\pi}\log|1-e^{i\theta}| d\theta$ Here is exercise 11, chapter 3 from Stein &amp; Shakarchi's Complex Analysis II:  Show that if $|a|&lt;1$, then:  $$\int_{0}^{2\pi}\log|1-ae^{i\theta}|\,d\theta = 0$$  Then, prove that the above result remains true if we assume only that $|a|\leq 1.$ ($a\in \mathbb{C}$)  I've already proved it for $|a|&lt;1$, but couldn't make it for $|a|=1$, which I thought would be the easy part. But the only thing I could come up with was that, WLOG, it is enough to prove that:  $$\int_{0}^{2\pi}\log|1-e^{i\theta}|\,d\theta = 0$$  Tried to look for some kind of symmetry, but could't find it. Any ideas? Thanks! Tentative definitions in C and linking