I have six directories with command files. These are /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin and /usr/local/sbin.  What are the differences between these? If I'm writing my own scripts, where should I add them?    Related:
In Windows there’re perhaps only a couple of important folders (by important I mean important in my logical picture of the Windows file system) in the installation drive (in my case C:\). Namely Program Files and Windows. I simply stay away from Windows folder and the “add remove program files” is good enough to handle the program files folder of Windows. Of course there’s a folder named Users where the users (who are not admins) can access only their folders.  Thus there’s a clear picture at some level in my mind of the Windows file system. In Ubuntu, when I reach the location /, there’s a huge list of folders, most of which I have no clue as to what they contain. The /bin folder seems to be the equivalent of the Windows folder in windows. The /usr folder seems like it’s the equivalent of the Users folder in Windows. But even the /home folder looks like it can fit the bill.  Please understand that I do understand, that Ubuntu (Linux) has a different character than that of Windows, i.e., there need not be exact equivalent of Windows functions, in Ubuntu. All I am looking for is a bit more clearer picture of the Ubuntu file system.   This question is a part of a bigger question which I am splitting up to make it more answerable. The original question can be found here:
Where can I install ubuntu if I have 4 primary partitions? I want to triple boot Windows 7, Backtrack, and Ubuntu. Windows and Backtrack are already installed. The problem is that both of them take 4 partitions: 3 for Windows, and 1 for Backtrack. When I try to make another partition, it says I can't have over 4. How can I install Ubuntu with this problem? Note: The 3 Windows partitions are PQSERVICE, SYSTEM RESERVED, and eMachines. I don't really know if I can delete one. Installing drivers for windows? How to uninstall a package installed from snapcraft? I used this command line  sudo snap install pwgen-tyhicks   to install pwgen but I can't findout how to use it. So I want to uninstall it. How to  uninstall it? Difference Boolean modifier. How do I get it to work with my mesh? I want to make a screw head, but I can't get the cross in the screw head; the Boolean modifier doesn't work.  Link: Why doesn't the frequency of light change during refraction? Why shouldn't root be allowed to login via ssh? why should root access be disabled for ssh? I always hear that's for security reasons. But I don't get it. What's different to login as non-root and then sudo su -? What's the preferred way to handle tasks that need privileged permissions?  Thanks  Thomas A general question asked from time to time on stack exchange is question of trigger bulkification.  Therefore I have 2 questions:   Which best practices are you using? What is the best way to handle updates of more than 200 records? (In case of more than 200 records the trigger is executed more than once.) Capacitor discharging through no load? What exactly would happen in the ideal case where a capacitor were to discharge into a wire with zero resistance?  Like in here:  There is still charge on one plate of the capacitor, which will try to go to the other plate to make $\Delta V = 0$ across the capacitor, so there has to be a current $I$.  But as more charge goes to the other side of the capacitor, the more repulsion these will cause to more coming towards them. So I am assuming current cannot just be constant?  I am starting from $$ I = C \frac{dV}{dt}, $$ but I know neither $V(t)$ nor $I$. wrappers and JavaScript pop-up? Use Case:  What i want is a list of records, and allow this user to choose 2 of those records, then click a button to go to a new VF page, if the user selects more than 2, i want him to get a notification of some kind saying you need to select 2 records, I do not want the page refeshed though.  Strategy:  I'm creating a wrapper class for the records like this:  and i have that part going by creating a custonm controller... I need the notification part working.   Problem:  I don't know how to call methods from the customController in javascript Also, i do not want to refresh the entire page. I just want them to go back to where they were. I was thinking a pop-up notification but I'm flexible.. The meaning of various equality symbols Mathematical Basis behind inflation of Standard errors of Regression estimates due to multicollinearity We know that due to multi-collinearity, the standard errors of beta estimates get inflated. But what is the mathematical basis to it?   I am looking for some mathematical relationship or something to explain this.   Like I understand if standard error of betas goes up, then t-statistics goes down and we might not be able to reject the null or the variables would appear non-significant.   But what is the mathematical relationship between multicolllinearity and inflation in variance of coefficients? Can we get an alternative to the "That solved my problem!" button that doesn't make the presumption that it solved my problem? I.e. "Yes, that's the problem I have."  In some cases, SE (et. al.) answer something, but the answer really doesn't solve it, it was a "cop-out" -- a "we know there's a problem, but there's currently no fix or workaround". Can we get a button that indicates that "Yes, I acknowledge I have that same problem, and I may have even tried those solutions, but it's not solved by any means." button or something?  I get the purpose of it - make it more friendly and easier to remove duplicates, but I refuse to say "That solved my problem!" if I still have a problem (mostly on principle). I'd rather have a "Ah yes, that's my issue! But, it seems like there's no actual solution there."  As an example: How should duplicate questions be handled? What should I do when I see a question that is a duplicate of another one?   Should I answer it? Should I downvote it? Should I comment? Should I edit the question to indicate it's a duplicate? If I can, should I (vote to) close the question? What happens when I vote to close as duplicate? Or: Why did a comment with my name on it just appear? Should I flag it for moderator attention? What about similar or related questions? How to fill in the Schengen visa application form when going to several countries? I will be traveling to France, Italy and Germany with France being my main destination. So I am applying in the French consulate for Schengen visa. I will be traveling on my own and will be staying in hotels.  I had some doubts with regards to filling the application form for Schengen visa.    Q22- Member State(s) of destination: Should I fill in all three of my destinations ? Q31 Surname and first name of the inviting person(s) in the Member State(s). If not applicable, name of the hotel(s) or temporary accommodation(s) in the Member State(s) : This field has barely a line of space to enter. Should I just enter the hotel name in France (my main destination) ?  Q32 Surname and first name of the inviting person(s) in the Member State(s). If not applicable, name of the hotel(s) or temporary accommodation(s) in the Member State(s): Same problem as Q31. Very little space. Should I just enter address of the one hotel I entered in earlier Q ? Windows registry entries for default explorer view I'm making an automated installer for Windows XP, and I want the default view to be the "details" view on all folders - that is, the effect gotten by setting one folder to the details view, then going to Tools -> Folder Options -> View -> "Apply to All Folders". I also want the status bar to be showing, same as going View -> Show Status Bar.  What registry entries should I modify, and to what, to have this be the case? What are the solutions to $z^4+1=0$? I've heard that you always want the same size of RAM (2x1GB sticks) but does their placement matter? I have four slots on my motherboard but does it matter if the sticks are not adjacent?  This particular question involves the How can I insert a line break in a TikZ node? Simply putting \\ where I want the break doesn't work (see MWE).  Is there a way to make lines break automatically at some specified width?  And can I control the alignment of the text (left, right, centered, justified)?  \documentclass{article} \usepackage{tikz} \begin{document} \begin{tikzpicture} \node {First line\\second line}; \end{tikzpicture} \end{document} I have a question about the following problem from a Putnam review:  Let $n\in \mathbb{N}$. Find how many pairs of natural numbers $(x, y)\in \mathbb{N}\times \mathbb{N}$ solve $$ \frac{xy}{x+y}=n. $$  I have found some solutions for all $n$, such as $(2n, 2n)$ and $(n+1, n(n+1))$, but I feel as though this is the wrong approach, as the question is only asking for the number of solutions to the equation.  I don't really want a complete solution, but any hints would be greatly appreciated. Find a recurrence relation for the number of $n$-digit binary sequences with no pair of consecutive $1$s.  I know my base case:$$a_1 = 2$$ for either $1$ or $0$. Normally to construct the recurrent relation I would say fill in $n-1$ spaces then add a $1$ or $0$, which is simply:$$a_n = 2\cdot a_{n-1}$$However, I don't believe this is right, because this doesn't take into account that there can't be any consecutive $1$s.  Even when I use the base case of $2$ digits:$$a_2 = 3$$for either $01$, $10$, or $00$, I still get the recurrence relation of:$$a_n = 3\cdot a_{n-2}$$which also does not account for $01$ and $10$ occurring consecutively.   So how would I express this?