Bash regex match not working - escaping all special characters
bash regex with quotes?
In a custom lightning component where one is using the recordEditForm tag, how can one validate fields that are filled by the user?  For example, in a quick action to create a Case record, we can have the following line inside the recordEditForm:  &lt;lightning:inputField aura:id="caseAccount" fieldName="AccountId"/&gt;   How can one enable or disable a button if certain fields are assigned by the user? Like if the account is specified, then a button on the component is enabled for the user.  Making the field required is not an option. Zero visibility while editing a message in a chat room $\lambda=\frac{2h}{p}$ instead of $\lambda=\frac{h}{p}$? I am studying quantum physics and there is something I don't understand:   I know that for any particle $E=hf$ (Einstein relation) and  $v=\lambda f$ ($v$ is the speed of the particle). I also know that the kinetic energy is $E_k=\frac{mv^2}{2}$.    Solving those 3 equations for $\lambda$:  $$h\frac{v}{\lambda}=\frac{mv^2}{2},$$ I finally find $$\lambda=\frac{2h}{mv}=\frac{2h}{p},$$ which is not consistent with the De Broglie relation $$\lambda=\frac{h}{p}.$$ Where am I wrong in my development? In my cssh config file, I have:  terminal_font=6x13   this default font is too small for me.   man cssh says, I can specify other font size with the -f argument, while using "standard X font notation".  is a wikipedia page containing some other fonts types. Unfortunately, none of these work for me:  $ cssh host1 host2 -f "7x14" Fatal: Unrecognised font used (7x14). Please amend $HOME/.clusterssh/config with a valid font (see man page).   Why does "7x14" not work?  How can I use bigger fonts with cssh ? If $A$ is a non-square matrix with orthonormal columns, what is $A^+$? If a matrix has orthonormal columns, they must be linearly independent, so $A^+ = (A^T A)^{−1} A^T$ . Also, the fact that its columns are orthonormal gives $A^T A = I$. Therefore,  $$A^+ = (A^T A)^{−1} A^T = (I)^{-1}A^T = A^T$$  Thus, $A^+ = A^T$. Am I correct? Thank you. How to add a gif file to my LaTeX file? Related:          I have an image file -- a gif file, which is the graph of a function. How do I add it to a LaTeX file? Will it come out OK in the subsequent pdf file? If a set is $F_\sigma$ and is of first category then it is a countable union of closed nowhere dense sets We say a set is $F_\sigma$ if it is a countable union of closed sets. We say a set is of first category if it is a countable union of nowhere dense sets.  The question is, if a set of $F_\sigma$ and of first category, is it true that this set is a countable union of closed nowhere dense sets. Computing the integral of $\log(\sin x)$ How to compute the following integral?  $$\int\log(\sin x)\,dx$$    Motivation: Since $\log(\sin x)'=\cot x$, the antiderivative $\int\log(\sin x)\,dx$ has the nice property $F''(x)=\cot x$. Can we find $F$ explicitly? Failing that, can we find the definite integral over one of intervals where $\log (\sin x)$ is defined? Find the value of $x,y$ for the equation $12x+5y=7$ using number theory . I tried the solution using other ways like:  $12x+5y=7$  $12x=7-5y$  $x=7-5y/12$  putting the value of $x$  $12(7-5y/12)+5y=7$  both $12$ will cancel out  $7-5y+5y=7$ here comes the problem please help me ? Is it okay to ask a professor from another university for class lecture notes of a course that he offered on that university? I find two very interesting courses that were offered in the Spring 2019 semester at ETH Zürich. Unfortunately, their class lecture notes are not shared publically. I wonder if it is appropriate to email the professors and ask them for class notes. Where and why do I have to put the "template" and "typename" keywords? In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway?    I have the following code:  template &lt;typename T, typename Tail&gt; // Tail will be a UnionNode too. struct UnionNode : public Tail {     // ...     template&lt;typename U&gt; struct inUnion {         // Q: where to add typename/template here?         typedef Tail::inUnion&lt;U&gt; dummy;      };     template&lt; &gt; struct inUnion&lt;T&gt; {     }; }; template &lt;typename T&gt; // For the last node Tn. struct UnionNode&lt;T, void&gt; {     // ...     template&lt;typename U&gt; struct inUnion {         char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U     };     template&lt; &gt; struct inUnion&lt;T&gt; {     }; };   The problem I have is in the typedef Tail::inUnion&lt;U&gt; dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion&lt;U&gt; names a type and not a function? How to rename multiple files sequentially from command line? How to rename file as below  AS1100801000002.RAW7AGS  AS1100801001008.RAW7AH4 AS1100801002001.RAW7AH9 AS1100801003002.RAW7AHE AS1100801004009.RAW7AHT AS1100801005002.RAW7AHY AS1100801010002.RAW7AJ3   to new name  AS1.txt AS2.txt AS3.txt AS4.txt AS5.txt AS6.txt AS7.txt Is there a word for someone who somewhat delights in their illnesses/medications? linux find command to move files I am new to the telecom simulations system specially multisim, which I am having a project that I want to simulate.  My project in (Analog Communications) is consisting to have FM Transmitter (Modulator) that accepts a generated signal (Sin, Cos) and get me the modulated output as a Graph.  I've found this FM transmitter circuit (3 km range):   ![two muppets][1]  and I am building that circuit on Multisim, and I failed. Because I faced many problems, first of, the variable capacitor symbol is weird here in the multisim, and the regular capacitor doesn't have variable options. Secondly, when I Use signal generator as (Sin, Cos), the output gets weird after 5 second of the simulation.  I want to show the input signal (before modulation) and the output signal (transmitted or modulated).  I guess my output result where not the as expected, as the signal (Sin with phase 90&deg;) is giving weird result of few seconds of simulating.  Below are screenshots of the simulation results within time.          Any ideas how to edit or fix the above circuit to have this output is similar to what it should be? Flagging multiple comments versus flagging the whole post for moderator attention When multiple comments in a comment thread ought to be removed (especially if they're all for the same reason), should I flag each of them individually or flag the parent post for moderator attention?  I've usually adopted the former strategy - flagging each comment with the same flag reason, often a custom one copied and pasted. I had always assumed the following things that led me to follow this strategy:   Flagged comments were discretely marked as flagged in some way when the reviewer viewed the question (much like how I can see others' pending suggested edits now that I have editing privileges). By individually flagging all the comments that needed cleaning up, I was allowing the flag reviewer to see at a glance which comments needed removing, thereby providing them with useful additional information that wouldn't be available if I flagged the entire parent post. By flagging comments individually, rather than flagging the whole post, I was letting my flags be handled by anyone with 10k+ rep and access to the mod tools, rather than having to be handled by a diamond moderator.   However, I just read  (now deleted) by Shog9 that makes me suspect that approach is misguided, and question whether any of my assumptions about how comment flags work are actually true. Notably he says:     If you'd pinged me once for every comment in that thread you found noisy, I would probably be plotting my revenge instead - at very least, I would think you very rude for doing so. Yet, that's exactly what you're doing when you start flagging multiple comments in a single thread: instead of taking a few seconds to describe a problem, you're attempting to use a moderator as a tool to do your bidding, without any real effort to communicate.   He also said some more stuff on the topic - I think there was something about huge offensive boxes blotting out the UI when he views questions with multiple flags - but I now can't recover it any more because that question was deleted while I was in the process of writing this one, and it doesn't seem to be available in the Google cache.  Much of the flagging and review system is still a black box to me as a low/mid rep user, and it's difficult for me to figure out what flagging behaviors are appropriate and helpful when I have no idea what actually happens when I flag a comment. (The Privileges section doesn't mention comment flags anywhere that I can find. I don't even know who reviews them at the moment, and can't find a Meta question anywhere that addresses that.)  Could somebody provide some input on when (if ever) flagging lots of individual comments in a thread is appropriate, and when flagging the entire parent post is? A pretty screenshot of the UI of the relevant review/mod tools, demonstrating the effect of each approach, might also be helpful for understanding this, if that's not asking too much. Is it possible to set a CNAME record at the top of a domain? (i.e. @ CNAME www, @ CNAME foobar.com., etc.)  My ISP says that it's only possible to use CNAME's for subdomains but I've read somewhere else that is should be possible even if not recommended. I block everything Google, including Google APIs, as I don't like to to have Google tracking all of my usage on the Internet. Is there any way to use Stack Exchange without Google APIs?  I usually am browsing with Windows 7 and Firefox, but of course not Firefox with StackExchange. How to force Windows 7 to ask for a "fresh" IP address from DHCP server? I'm troubleshooting a certain issue with my DHCP configuration, and need my Windows machine to ask for a "fresh" IP address, so I can see which address DHCP server gives by default.   When I do ipconfig /release followed by ipconfig /renew, Windows "proposes" its old IP address to the DHCP server (just checked with Wireshark, initial "DHCP Discover" message has Option-50 (requested IP address) with Windows machine's old IP).  Tried disabling/enabling network adapter. Same behavior.  Question: How can I force Windows to just ask for a new IP address, without proposing its old IP address. Difference between static class and singleton pattern? What real (i.e. practical) difference exists between a static class and a singleton pattern?  Both can be invoked without instantiation, both provide only one "Instance" and neither of them is thread-safe. Is there any other difference?