I have two backup directories (dir1 and 2) on two different (local) HDDs and I want to create one of them. How can I really sync their contents so that both directories will have the same contents?
Having migrated to Linux from Windows, I would like to find an alternative software to Winmerge or rather learn command line tools to compare and sync two folders on Linux. I would be grateful if you could tell me how to do the following tasks on the command line... (I have studied diff and rsync, but I still need some help.)  We have two folders: "/home/user/A" and "/home/user/B"  Folder A is the place where regular files and folders are saved and folder B is a backup folder that serves as a complete mirror of folder A. (Nothing is directly saved or modified by the user in folder B.)  My questions are:   How to list files that exist only in folder B? (E.g. the ones deleted from folder A since the last synchronization.) How to copy files that exist in only folder B back into folder A? How to list files that exist in both folders but have different timestamps or sizes? (The ones that have been modified in folder A since last synronization. I would like to avoid using checksums, because there are tens of thousands of files and it'd make the process too slow.) How to make an exact copy of folder A into folder B? I mean, copy everything from folder A into folder B that exists only in folder A and delete everything from folder B that exists only in folder B, but without touching the files that are the same in both folders.
Entire one-to-one functions are linear Can we prove that every entire one-to-one function is linear? How to see the full date on macOS Big Sur? How can latex and pdflatex be both symbolic links to same executable (pdftex) and not behave the same? When I run  $ latex my_doc.tex   and   $ pdflatex my_doc.tex   it works, and when I run  $ pdftex my_doc.tex   it doesn't work.  The thing is I noticed that both LaTeX and pdflatex commands are symbolic links to the same pdftex executable. That is,  $ which latex pdflatex pdftex   yields  /usr/bin/latex /usr/bin/pdflatex /usr/bin/pdftex   and   $ ls -l /usr/bin/latex /usr/bin/pdflatex /usr/bin/pdftex   yields  /usr/bin/latex -&gt; pdftex /usr/bin/pdflatex -&gt; pdftex /usr/bin/pdftex   So how is it possible that commands being symbolic links to a same executable do not behave in the same way ?  Thanks.  I have Ubuntu 12.10 with TeXLive-full 2012.20120611-4 installed. Where to start with Oracle? This question only needs one answer: a list of great resources for getting started with Oracle, including Database Administration, PL/SQL and SQL.   You may find your question has been closed as a duplicate of this one, if so, please don't be offended: we are trying to be as helpful as we can without . Closing a question as a duplicate of this one is us saying "What you really need is to spend some time reading some of the best resources available rather than have your specific question answered right now. If you do get through these resources, you'll soon be back with more ! Merle the Wizard is fighting enemies with his friends on a bridge. He wants to cast a spell on the BBEG, but they are currently out of range and so he uses his action to ready a spell for when the BBEG is in range.  However, before that happens one of Merle's friends is knocked off the bridge. Can Merle ignore the spell he had readied and use his reaction to cast feather fall? Integrated circuits seem to have standard voltages of 5 V, 3.3 V, 2.5 V, 1.8 V, etc.  Who decides these voltages? Why do smaller devices require lower voltages? Discourage questions being marked as answered within an hour or so of being posted Given an instance of System.Reflection.Assembly. Which of these are acceptable? Is one preferable over the other?   "Chemically-deposited tourmaline is never periwinkle." "Chemically deposited tourmaline is never periwinkle."   Also, is the title to the this question asking what I'm trying to ask?  (I realize that there are other questions about hyphenation in similar contexts; I'm asking specifically about -ly adverbs.) Say I had a Core i7 Laptop with 16GB of RAM and a 750gb drive.  Is there a mechanism where I can partition the HD into a Linux, Windows, OS X, Shared Data, Hypervisor setup where I boot a small hypervisor. I can start/stop a linux, Windows and OS X virtual machine and interact with them all from the hypervisor?   Code, Test, etc?  is this a type 1 Hypervisor?  I suppose I could run a small linux install and VmWare but could VmWare read the virtual machines from a physical hard disk partition versus a file based setup (.vmdk files)? Is there something wrong with VertexConnectivity Prove that:$\int_{a}^{b} f(x) dx = b \cdot f(b) - a \cdot f(a) - \int_{f(a)}^{f(b)} f^{-1}(x) dx$ Values of the limit $\lim\limits_{x\to+\infty}\left(\sqrt{(x+a)(x+b)}-x\right)$ Hi I have a question regarding finding the values of limit for the following question.  Let $a, b \in \mathbb R$. Find the limit $$\lim_{x\to+\infty}\left(\sqrt{(x+a)(x+b)}-x\right)$$ How to inject keystrokes via a shell script? I'm trying to inject keystrokes into the input daemon so as to simulate typing from a Bash script. Is this possible, and if so, how can I make it happen? I get double question marks when referring to labels inside figures I have some charts embedded in figures, and I want to be able to refer to them easily using the "Figure x" notation. I'm doing it like this (in this order):  \documentclass[12pt,letterpaper]{article}  ...  \section*{Results} ...we performed a linear regression to obtain a standard curve  (Figure~\ref{0:stdcurve})....  \pagebreak \section*{Results (Graphs)} \subsection*{Construction of Standard Graph for PNP} \begin{figure}[h]   % Figure 1     \centering     \includegraphics[scale=1]{kinematics-res/graph0-1}     \caption{The standard curve for PNP.}     \label{0:stdcurve} \end{figure}   However, instead of getting the output "...to obtain a standard curve (Figure 1)...", I just get "...to obtain a standard curve (Figure ??)..."  I also noticed that the PDFLaTeX compiler is generating warnings saying that it couldn't find the reference of the name 0:stdcurve. Why am I getting these warnings? Error on \usepackage {geometry} text property The following produces error! The error is solved if no space exists between text= and {5in,8in}. This is really weird! Why is this happening with LaTeX?  \documentclass[a4paper,10pt,onecolumn,oneside, portrait]{article}  \usepackage[text= {5in,8in},centering]{geometry}  \begin{document}      \section{What Endogenous uncertainty is:}  yes  \subsection{Type as it is : Stochastic and determ! } on  \subsubsection{Well there is more than it} Yes    \end{document} I have the following title page in LaTeX: \documentclass{article}  \title{Appendix A: User Manual}  \author{ John Smith\\University XYZ\\Albert Square\\Walford\\NC1 8AE }  \begin{document} \maketitle \end{document}  What is the proper way to add a new page, say, for the contents page and start editing that new page? Upgrading straight handlebars to drop handlebars What does E mean in 9.0122222900391E-5? I often find this at the bottom of pages.  Page generated in 0.00013899803161621  Sometimes, I come across  Page generated in 9.0122222900391E-5  What does that time mean? I tried searching Wikipedia for E and maths but found the . My guess is E stand for Exponential and -5 is the power it is raised to. And the displayed time is a really small number. But that doesn't make sense when compared to the other time in the question. 0.00013899803161621 is bigger than 9.0122222900391E-5. If it means x times $10^{-5}$, then 9.0122222900391E-5 will be 0.000090122222900391 which is smaller than 0.00013899803161621. What does E stand for? Am I required to pay UK/ USA Visa fees if I have a German residence permit? Here is the situation. I am non-european but staying in Germany with a Residence permit. I can visit all Schengen listed countries with no issue. Assuming that I would want to travel to a non-Schengen country e.g. UK or USA, can I use my residence permit to travel there or am I required to apply as a citizen of my country? Assuming Germans are not required to pay Visa fees to that country, will I have to pay since I only have a residence permit? Third case, Europeans can fly directly to the airport of some countries and apply for a visa from there. In some other countries, you are required to book a Visa appointment at the embassy, which may be granted or not. Does that apply for one with a residence permit?