subject placeholder - It is reported that, It appears that Is "it" a subject placeholder in the sentences below?     It is reported that one ancient Greek athlete ate dried figs to enhance training.      It appears unlikely that interest rates will fall.
What does the word "it" mean? Even if determinism isn't true for everything that happens—even if   some things just happen without being determined by causes that were   there in advance—it would still be very significant if everything we   did were determined before we did it. However free you might feel when   choosing      [Thomas Nagel - What does it all mean? p.52]   What does the word "it" mean?
What is the source of help? help  displays information about builtin commands. What is the source of help? Does it maintain a database for builtin commands, or does it read some files of each builtin commands (similar to the manpage of each utilities)?  Sometimes I find its information seems to expand that by --help  $ cd --help bash: cd: --: invalid option cd: usage: cd [-L|[-P [-e]]] [dir]  $ help cd cd: cd [-L|[-P [-e]]] [dir]     Change the shell working directory.      Change the current directory to DIR.  The default DIR is the value of the     HOME shell variable.      The variable CDPATH defines the search path for the directory containing     DIR.  Alternative directory names in CDPATH are separated by a colon (:).     A null directory name is the same as the current directory.  If DIR begins     with a slash (/), then CDPATH is not used.      If the directory is not found, and the shell option `cdable_vars' is set,     the word is assumed to be  a variable name.  If that variable has a value,     its value is used for DIR.      Options:         -L  force symbolic links to be followed         -P  use the physical directory structure without following symbolic         links         -e  if the -P option is supplied, and the current working directory         cannot be determined successfully, exit with a non-zero status      The default is to follow symbolic links, as if `-L' were specified.      Exit Status:     Returns 0 if the directory is changed, and if $PWD is set successfully when     -P is used; non-zero otherwise.   I thought help extract the help part of the executable, but for a  python script , it isn't  $ help ./pdf-merge.py bash: help: no help topics match `./pdf-merge.py'.  Try `help help' or `man -k ./pdf-merge.py' or `info ./pdf-merge.py'.  $ ./pdf-merge.py --help usage: pdf-merge.py [-h] [-v] [--ask] [--output OUTPUT] [--title TITLE]                     [--author AUTHOR] [--keyword KEYWORD] [--pdftk PDFTK]                     [--gs GS] [--pdfmarks PDFMARKS] [--unicode]                     PDF [PDF ...]  Merge PDFs preserving bookmarks. Thanks to Larry Cai for suggesting that Unicode be supported and for discussion about the `--pdfmarks` option.  positional arguments:   PDF                  an input PDF to merge  optional arguments:   -h, --help           show this help message and exit   -v, --version        show program's version number and exit   --ask                pause for manual pdfmark tweaking   --output OUTPUT      name of the output PDF   --title TITLE        title of output PDF   --author AUTHOR      author of output PDF   --keyword KEYWORD    keywords for the output PDF   --pdftk PDFTK        path to the pdftk executable   --gs GS              path to the gs (Ghostscript) executable   --pdfmarks PDFMARKS  path to pdfmarks file. If not given, a temporary file                        is used. If given and the file is missing, execution                        will stop after the file is created (before the                        Ghostscript run). If given and the file exists, no                        attempt will be make to use pdftk to generate the mark                        file (I assume your input file is what you want).   --unicode            instead of merging PDFs, convert PDF-formatted unicode                        strings. For example `--unicode '&lt;FEFF03B103B203B3&gt;'                        \u03b1\u03b2\u03b3` How does the tester screwdriver work? How does the tester screwdriver work? If I put the tester screwdriver inside the "hot wire" of an electrical socket, it lits up if I press my finger against the metal cap on top of the screwdriver. This happens also if I stand on a surface of isolating material, such as wood. I read elsewhere that this happens due to stray capacitance formed by the "hot wire", the human body, and the ground. One has  $$ Z = R + \dfrac{1}{j \omega C}  $$  for the impedance, so if C  is high enough, the impedance should be close to r , the "effective resistance" of the formed circuit. Here I get lost; why r  is small enough to cause a current in the range of mA  even if I stand on an isolating surface?  So really what I am asking is how one may represent the system hot wire - screwdriver - human body - wooden floor - building - ground as an electrical circuit, and which parts of the physical system contribute to the resistance, capacitance (and inductance?) and in which proportion, even very approximately. How to chat to all I very rarely see chats too all and don't know how to do it myself. Normally it's SHIFT + ENTER The following hotkeys have been tried: - SHIFT + ENTER - CTRL + ENTER - ALT + ENTER Triple Boot Lion+Win7+Linux Why no ooVoo on ubuntu? The only reason I ever boot into Windows (7) is to use the popular video chat software ooVoo (). It's useless under Wine and there seems to be no way to run it in Ubuntu except for some proprietary tools. Does anyone have any information on some alternatives to running it with Wine? Why was Padmé made to clean an astromech? Reading  (the Amidala stand-in) I remembered that I always wondered why she ordered the actual queen to scrub R2-D2. There were enough actual servants who could have done it, so why Padmé? If that wasn't enough, after giving the actual queen (Padmé) the order to go away, she tells Panaka to continue with the discussion. How does that make sense?  The significant piece of dialogue:     AMIDALA : Thank you, Artoo Detoo. You have proven to be very loyal...Padme!    ...    AMIDALA : (Cont'd) Clean this droid up the best you can. It deserves our gratitude...(to Panaka) Continue, Captain.   Note that this question is two-fold:   Why was Padmé chosen in the first place? Why would an important meeting with the ship's captain be continued without her? Is there any measurable time dilation when Earth reaches perihelion? Can we measure such a phenomena relative to the motion of the outer planets? What data type to use for hashed password field and what length? I'm not sure how password hashing works (will be implementing it later), but need to create database schema now.  I'm thinking of limiting passwords to 4-20 characters, but as I understand after encrypting hash string will be of different length.  So, how to store these passwords in the database? I'm not that into dynamic programming languages but I've written my fair share of JavaScript code. I never really got my head around this prototype-based programming, does any one know how this works? var obj = new Object(); obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test();  I remember a lot discussion I had with people a while back (I'm not exactly sure what I'm doing) but as I understand it, there's no concept of a class. It's just an object, and instances of those objects are clones of the original, right? But what is the exact purpose of this &quot;.prototype&quot; property in JavaScript? How does it relate to instantiating objects? Update: correct way var obj = new Object(); // not a functional object obj.prototype.test = function() { alert('Hello?'); }; // this is wrong!  function MyObject() {} // a first class functional object MyObject.prototype.test = function() { alert('OK'); } // OK  Also these  really helped a lot. Application of Kolmogorov's Zero-One Law Most of the books I read, they only state some examples of tail events. One of them is  $[\sum_n X_n \ converges]$. My main problem is to show that this is indeed a tail event. What is the proper name for a "river plot" visualisation In a famous plot, Charles Minard visualised the losses of the French Army in the Russian campaign of Napoleon:    (another nice example is  xkcd plot)  Is there a canonical name for this type of visualisation? I'm actually looking for an R package to create such plots, but I don't even know how to look for it.  EDIT:  As I could not find a good package in R do do this type of plots, I have created my own, called "riverplot" -- you can download it . Here is a simplified version of the above diagram:    And an example of what other diagrams can be created with the package: Is there a way to change the environment variables of another process in Unix? How to create a permanent "alias"? If you create an alias for example:   alias cls="clear"   It exists untill you kill terminall session. When you start a new terminal window the alias doesn't exist any more. How to create "permanent" alias, one that exists in every terminal session? Deployed web parts don't show up in Web Part Gallery I'm running an Ubuntu 14.04 and want to install the Eclipse IDE for both Java and C/C++ programming. I installed the separate installation files from their official website. I followed this thread . (The top answer)   The steps helped me install the Java IDE but I don't know what changes I should make to the procedure to install the C/C++ IDE.   Another thread , recommended to install eclipse-cdt but the Eclipse version installed is outdated. (Doesn't allow me to install Pydev)   I have TWO questions:   Can the C/C++ libraries be downloaded from within eclipse, like Pydev? If not, how do I install both IDEs without interfering with each other?   P.S. I commented this query in the first thread but got no reply, that is why I'm asking a fresh question! I installed Dev C++ using Wine on Ubuntu 18.04 and the program is compiling but it not showing any output screen. Makeindex error when ! used in \index in align environment See MWE below. The symbol ! in the \index causes an error. This is only the case in align environments (not in equation). So it seems to have to do something with amsmath. If ! is put in an \mbox there is no error. But then of course the font size is not adjusted to subindices. Curiously enough, \index{$C_{K!!}$} (two exclamation marks) doesn't cause any error.    \documentclass{article} \usepackage{amsmath} \usepackage{imakeidx} \makeindex \begin{document} \begin{align} y\index{$C_{K!}$} \end{align} \printindex \end{document}     Any solutions suggested? How do I evaluate these fork() calls with the && and || operators in C? Remove rogue app from menu bar From this  on Bayesian Least Mean Square estimation:  $$\mathbf E\left[(\Theta -\hat\theta)^2\right] = \rm{var}(\Theta -\hat\theta) + \left(\mathbf E[\Theta -\hat\theta]\right)^2 = \rm{var}(\Theta) + \left(\mathbf E[\Theta -\hat\theta]\right)^2$$  which is to say that $\rm{var}(\Theta -\hat\theta) = \rm{var}(\Theta)$.  I would like to ask how that comes about?  Thanks.  $\Theta$ is the random variable being estimated, and $\hat\theta$ is a constant estimate.