This works   find ./ -iname '*.c' -o -name '*.h' -o -name '*.l' -exec grep -irn test1 {} \;   If I combine -exec with ls then it tells me that is improper option.  #ls -exec touch {} \; ls: invalid option -- 'e' Try 'ls --help' for more information.   Is my understanding correct that -exec option is used only by find and not by other commands?
I find myself constantly looking up the syntax of  find . -name "FILENAME"  -exec rm {} \;   mainly because I don't see how exactly the -exec part works. What is the meaning of the braces, the backslash and the semicolon? Are there other use cases for that syntax?
Could not get lock /var/lib/apt/lists/lock when I try to apt-get update I'm getting the below error,  E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable) E: Unable to lock directory /var/lib/apt/lists/ Why is notepad++ writing to my new document? I updated notepad++ and it started writing to the screen.  I quickly closed it not knowing what it was, but now I'm curious do I have a 'hacked' copy of notepad++? Windows Server 2008 R2: User account set to not show on login This afternoon I set up a Win Server 2008 R2 system for use with Team Foundation source code control. In order to give my team-mates the right to connect, I had to create a user account for each person, 10 in total. (I can't, and I don't want to create a domain).  Now, after doing this, all user accounts are displayed in the login screen.  What can I do so that all the accounts are not displayed there? So basically , we all know the direction outside the magnet its from NORTH to SOUTH. but what i don't understand is that what is the direction inside is it the same ?? Apex PMD: Problem: Validate CRUD permission before SOQL/DML operation Background   I am using the Apex PMD plugin for VS Code and it's giving me this problem:     Validate CRUD permission before SOQL/DML operation   For this line of code:  insert contentVersion;   Which is part of this method:  private void attachReport(Id recordId) {      ContentVersion contentVersion = new ContentVersion(         versionData = Blob.valueOf(buffer.toStr()),         title = 'Import Report',         pathOnClient =  StringUtils.format('/Import-Report-{0}.txt', DateTime.now().getTime()),         FirstPublishLocationId = recordId);      insert contentVersion; }   Questions    Why am I getting the problem? What should I do to not get the problem?     Reference LibVLC.NET in GTK# Input field added through javascript not in PHP $_POST variable. How to fix this? Is it possible to set up and watch a game between just computer AI opponents? No human players, just AI and have the ability to scroll around and see what the AIs are doing with the turn management being also automated, so the AIs just end turn when they are done. Oh, and all of this hopefully without any sort of fog of war.  This way, I can see how the AI manages resources and units and maybe learn a thing or two as a civ newb. Can I remove receipts from imported products from my passport? I have recently imported books into Canada from Japan.  As I bought in excess of 5000¥, the purchase was tax free and the receipt was stapled to my passport and stamped.  Since I've now come back to Canada and no issues occurred with my imports, Is it safe to remove the receipts from my passport?  As it was stamped and stapled, there will remain a trace that something was there. Could this cause problems when I return to Japan at a later time? apt-get update, unlinking What is the relationship between regression and linear discriminant analysis (LDA)? Is there a relationship between regression and linear discriminant analysis (LDA)? What are their similarities and differences? Does it make any difference if there are two classes or more than two classes? What is the term for a sentence which reads same forwards and backwards? Please note, I'm not asking for a palindrome.  I mean to say that only the word  order is rearranged, not the actual spelling of the word.  An example might be as follows:     First ladies rule the State and state the rule: ladies first. Why do clocks measure arc-length? Apologies in advance for the long question.  My understanding is that in GR, massive observers move along timelike curves $x^\mu(\lambda)$, and if an observer moves from point $x^\mu(\lambda_a)$ to $x^\mu(\lambda_b)$, then his clock will measure that an amount of time $t_{ba}$ given by the curve's arc length; $$   t_{ba} = \int_{\lambda_a}^{\lambda_b}d\lambda \sqrt{-g_{\mu\nu}(x(\lambda))\dot x^\mu(\lambda)\dot x^\nu(\lambda)} $$ will have elapsed where $g_{\mu\nu}$ is a metric on spacetime with signature $(-,+,+,+)$.    Why is this so?     Here is how I would attempt to justify this fact in special relativity with $g_{\mu\nu} = \eta_{\mu\nu}$.  Consider an inertial observer $O$ in $\mathbb R^{3,1}$, and suppose that this observer sees a clock, which I'll call observer $O'$ moving around on a curve $x^\mu(\lambda)$.  If $O'$ were also an inertial observer, then given any event with coordinates $x^\mu$ as measured by $O$, observer $O'$ would measure the coordinates of the event to be $x'^\mu = \Lambda^\mu_{\phantom\mu\nu} x^\nu + x_0^\mu$ for some Lorentz transformation $\Lambda$.  If $O'$ is not inertial, then this is no longer true, and there is some more complicated family of transformations, say $T_\lambda$ between events as seen by both observers.  I would argue, however, that if we were to partition the interval $[\lambda_a, \lambda_b]$ into a large number $N$ of intervals $I_1=[\lambda_a, \lambda_i], \dots, I_N=[\lambda_{N-1}, \lambda_b]$ with $\lambda_n = \lambda_a+n\epsilon_N$ and $\epsilon_N=(\lambda_b-\lambda_a)/N$, then on each interval $I_n$, $O'$ is approximately an inertial observer in the sense that $$   T_{\lambda_n} = P_n + \mathcal O(\epsilon_N), \qquad (\star) $$ for some Poincare transformation $P_n$.  Then we would note that since $O'$ is stationary in his own reference frame, he measures his worldline to have the property $\dot x'^\mu(\lambda) = (\dot t(\lambda), \mathbf 0)$ so that $$   I_{ba}=\int_{\lambda_a}^{\lambda_b}d\lambda \,\sqrt{-\eta_{\mu\nu}\dot x'^\mu\dot x'^\mu} = \int_{\lambda_a}^{\lambda_b} d\lambda \, \sqrt{\dot t^2} = t(\lambda_b) - t(\lambda_a) = t_{ba} $$ On the other hand the integral on the left can be written as a Riemann sum using the partition above, and we can invoke ($\star$) above to get \begin{align}   I_{ba}  &amp;= \lim_{N\to\infty}\left[\sum_{n=1}^N \epsilon_N\sqrt{-\eta_{\mu\nu}\dot x'^\mu(\lambda_n)\dot x'^\nu(\lambda_n)}\right] \notag\\ &amp;= \lim_{N\to\infty}\left[\sum_{n=1}^N \epsilon_N\sqrt{-\eta_{\mu\nu}\dot x^\mu(\lambda_n)\dot x^\nu(\lambda_n)} + \mathcal{O}(\epsilon_N^2)\right] \notag\\ &amp;= \int_{\lambda_a}^{\lambda_b}d\lambda \,\sqrt{-\eta_{\mu\nu}\dot x^\mu\dot x^\mu} \end{align} Combining these two computations gives the desired result.  How do others feel about this argument?  I'm not completely comfortable with it because of the assumption $(\star)$ I made on $T_\lambda$.  I imagine that in GR a similar argument could be made by invoking local flatness of the metric. Series about being that could change sex and age - "The Morph*" I'm trying to remember information about a series of three books I read in the early 1980's (first book could have been published in the 1970's). The book featured a character who was a scientific creation of some sort. It was (initially, I believe) an assassin, and had the ultimate getaway scheme; with effort, it could change its body, becoming about 10 years younger and switching sex. It changed 4 or 5 times in the first book, coming down from a senior citizen to someone in their teens or twenties; in the second and third books, it changed once per book (by the last book, it was a child or a young teenager).  The first book was title something like "The Morph..." where whatever the word was that started with "Morph" was this creature. No recollection of the author's name, or the titles of the other two books.  I think the cover of the first book was predominantly yellow, with black silhouettes representing the character at the four ages seen in the book, and a black title. And/or, the book might have been published by DAW (all their books at the time had yellow spines with black letters). How to handle dynamic changing ID's In XPath? XPath select node with namespace Let $K/F$ be a finite field extension and suppose that $F$ is infinite. Is it possible to have a nonzero polynomial $p \in K[x_1,...,x_n]$ that vanishes in $F^n$? JSON URL from StackExchange API returning jibberish? Multiple TikZ keys with foreach How might the weight of a falling object affect the damage it causes? Fall damage is 1d6 per 10 feet. What adjustments if any should I make for objects falling on a player character? (e.g. a bear)  Assuming the objects are meaningful threats but not instant character death, should the weight of an object change the calculation, e.g. more then 1d6 per 10 feet.  Or is this more in the spirit of improvising damage chart? i.e. the setback (cat to face) dangerous (orc fell on me), and deadly (the large bear).  If this is house-rule territory does any one have any experience or advice beyond  relevant to 5e.