Python equivalent of "cd -"
How do I change directory back to my original working directory with Python?
How to read a single character from the user? Is there a way of reading one single character from the user input? For instance, they press one key at the terminal and it is returned (sort of like getch()). I know there's a function in Windows for it, but I'd like something that is cross-platform. I am trying to represent trade flows on a world map where the size and direction of arrows indicate the exports/imports of a given country.  This type of map is commonly found in magazines and newspapers. However, I find it extremely difficult to make.   Is there any function in ArcGIS for Desktop or any free software that would help me in making it? NSString to NSDate How to prove that: $\tan(3\pi/11) + 4\sin(2\pi/11) = \sqrt{11}$ Convergence to a Uniform Distribution $\newcommand{\floor}[1]{\left\lfloor #1 \right\rfloor} $  Show that if $P(X_n = i/n)=1/n$ for every $i = 1,...,n$, then $X_n$ converges in distribution to a uniformly distributed random variable $X$.  Convergence in distribution is defined as   $$P(X_n \leq x) \rightarrow P(X \leq x)$$  and I have that a uniform distribution with parameters $a$ and $b$ implies that  $$P(X \leq x) = \frac{x-a}{b-a}$$  I cannot go any further however. I feel like I don't know anything about $X_n$ - I don't even know if it is continuous or discrete. What I can just say is that   $$P(X_n \leq x) = \sum_{i=1}^\floor{x} \frac{1}{n}$$  where $\floor{x}$  means rounding $x$ to the closest lower integer. Paucity of words for relationships Please refer the following questions asked elsewhere on this site:       I am a native Hindi speaker; Hindi has a plethora of terms referring to relationships. To take a trivial example, the term uncle may refer to father's elder brother, father's younger brother, mother's brothers, father's sister's husband, mother's sister's husband, all of which have specific addresses in Hindi.  I discussed the same with one of my teachers. She had the opinion that the development of language mirrors the cultural moorings of the society that uses the language. Now, since all of the above relationships have distinct status and reverence in the Hindi speaking society, that calls for different addresses. That may well not be the case in English speaking societies.  Is that correct? What other linguistic reasons may account for such a dearth of vocabulary in English in this area? Continuous function positive at a point is positive in a neighborhood of that point Pretty much the problem asks if a function is continuous at the point $c$ and $f(c) &gt; 0$ then there exists a $d &gt; 0$ such that $\forall x$, $f(x) &gt; 0$ with $|x-c| &lt; d$.   I can understand what the problem means. That if a function is positive at a point then there is another point that's really close that'll also be positive. I can not prove this in a formal way though. I've tried using the intermediate value theorem and I do not know hot to implement it. Any ideas? Strange book where teen protagonist is sent to a warzone, uses illusory magic to grow male genitalia JavaScript 64 bit numeric precision Is there a way to represent a number with higher than 53-bit precision in JavaScript? In other words, is there a way to represent 64-bit precision number?  I am trying to implement some logic in which each bit of a 64-bit number represents something. I lose the lower significant bits when I try to set bits higher than 2^53.  Math.pow(2,53) + Math.pow(2,0) == Math.pow(2,53)   Is there a way to implement a custom library or something to achieve this? Run a command without making me wait On the CLI, sometimes a command I type takes a while to complete, and sometimes I know when that's about to happen. I'm a bit confused on "backgrounding" and such in Linux.  What is the most common (or user-friendly way) of telling the CLI that I don't want to wait, please give me back my prompt immediately. And if it could give me a progress bar or just busy-spinner, that would be great! I am developing an offline installer for all versions of Ubuntu, and I need Ubuntu's default installed packages list. Is there a way to get this information from any server (web server)? Any script to fetch any Ubuntu version's default installed packages list.  I will give the Ubuntu version, and the script will fetch the packages list.  Note: I need at least a server address. I can write a script for this. Using a Single system() Call to Execute Multiple Commands in C In an information security lab I'm working on, I've been tasked with executing multiple commands with a single call to "system()" (written in C, running on Fedora).  What is the syntax that will allow me to execute more than command through system()?  (The idea being you could execute arbitrary commands through a program running on a remote computer, if the program interacts with the OS through the system() call.)  I.e.:  char command[] = "????? \r\n";  system(command); How can I fix the non-stitched seam that is present after applying mirror modifier? derivative under integral intuition Access parent's parent from javascript object How do I quickly switch between weapons and spells? When  I see him quickly change his weapons and spells during combat. When he later goes inside his items, you can see a second smaller arrow next to the weapon that you can quickly change to in combat. How can I set such an alternative so that I can quickly switch weapon?  The screen doesn't seem to intuitively explain what key I need to use to do that... Why is the second order perturbative correction to the ground state energy always down? What is the most accurate way to retrieve a user's correct IP address in PHP? Non numbered chapter* header issue Resolve $\lim_{x \to 0} \frac {\tan 3x}{\tan 5x}$ I started resolving this limit:  $$\lim_{x \to 0} \dfrac{\tan 3x}{\tan 5x}$$  so:  $$\begin{align}\lim_{x \to 0} \dfrac{\tan 3x}{ \tan 5x} &amp; = \lim_{x \to 0} \dfrac{\frac{\sin 3x}{\cos 3x }}{\frac{\sin 5x}{\cos 5x}} \\ \\ &amp; = \lim_{x \to 0} \dfrac{ \sin (3x) \cdot \cos (5x)}{ \sin(5x) \cdot \cos (3x)}\\ \\ &amp; = \quad?\end{align}$$  Could someone help me please