Intel® Wi-Fi 6 AX201 module causing Wi-Fi not detected errors upon fresh install, Ubuntu 18.04LTS I am running a fresh install of Ubuntu 18.04LTS, and I am noticing that I cannot connect to the wifi. The error shown in settings is "Wi-Fi module not detected". How can I go about remedying this issue?   This is what I see checking to see the status of any networking hardware detected.  lshw -C network    *-network UNCLAIMED               description: Network controller        product: Intel Corporation        vendor: Intel Corporation        physical id: 14.3        bus info: pci@0000:00:14.3        version: 00        width: 64 bits        clock: 33MHz        capabilities: cap_list        configuration: latency=0        resources: memory:d541c000-d541ffff
WiFi Adapter AX201 Not Found: Ubuntu 18.04 Please note that this question is specific to Intel WiFi adapters.  My laptop is an HP ENVY with an Intel AX201 Wifi Adapter. I've dualbooted Ubuntu with Windows.  AX201 WiFi adapter is not supported by latest Ubuntu 18.04 version, because Ubuntu 18.04 comes with Linux Kernel 5.0, whereas support for AX201 comes built-in in Linux Kernel 5.2+. Canonical claims that Ubuntu 18.04 will get Linux Kernel 5.3 sometime next year. However, I wont be able to wait that long.  I tried downloading and installing Kernel 5.2.14, but I cant go beyond Grub: I get the error:     error: you need to load the kernel first.   Other option is to download the Intel Backport Driver, which I tried. That didn't seem to work either. As per the tutorials, I've restarted frequently, but that didnt work either.  Also I'm not quite sure if Intel IWLWIFI Backport driver supports AX201 in the first place.  WiFi works while I'm booted in Windows.  What should I do?  Thanks in advance!  UPDATE  I tried out @Pilot6's answer, and it worked. Thanks!  I have one last question: I've read that if you upgrade the Kernel beyond what Ubuntu 18.4 supports, its kinda unsafe (which I read as prone to system crashes).  I dont want system crashes because I have only one partition (root) for Ubuntu, and any crash would likely mean all my data is lost. One method forward would be to split my Ubuntu partition into root and home.  So if I want to access WiFi on my device safely without risking any crashes, what should I do?  My understanding of Ubuntu and Linux may be wrong as they are built on forum answers only. Please correct me if Im wrong anywhere.
In  video, he uses a command block to give him jump boost while he is wearing his Boots of Leaping.  I am trying to imitate this for a multiplayer map I am making. Wearing golden boots called "Stealth Boots" is supposed to give that player invisibility. I am using this command:  /effect @a[Inventory:[{Slot:100b,tag:{display:{Name:"Stealth Boots"}}}]] 14 30000 200  I do know that in the video he is using a /testfor command, but since I'm making a multiplayer map in order to use this technique I'd have to define a scoreboard variable for each player - and even then, the players would be finite. Thus, I want to be able to use the command DIRECTLY.  When I use that command, it either says "That player cannot be found" or "The entity UUID provided is in an invalid format" - the former of which I'm familiar with; the later I've barely ever seen before.  So, my method doesn't seem to work - how do I fix it? Understanding Dirac's notation Suppose I have a complex figure made ​​with TikZ. How do I use it several times without having to repeat all the commands?  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{tikz}  \begin{document}  Base figure  \begin{tikzpicture}   \draw[blue] circle (2);   \foreach \i in {0,10,...,350}     \draw[blue] (\i:1.9) -- (\i:2.1); \end{tikzpicture}  Using base figure.  \begin{tikzpicture}   \draw[blue] circle (2);   \foreach \i in {0,10,...,350}     \draw[blue] (\i:1.9) -- (\i:2.1);   \foreach \i in {0,10,...,350}     \node at (\i:2.7) {\tiny $\i^\circ$}; \end{tikzpicture}  Using base figure.  \begin{tikzpicture}   \draw[blue] circle (2);   \foreach \i in {0,10,...,350}     \draw[blue] (\i:1.9) -- (\i:2.1);   \foreach \i in {0,10,...,350}     \draw (0,0) -- (\i:2); \end{tikzpicture}  \end{document} Why does bright pure red/green/blue light look white if bright enough? I believe that white light is white because it contains every wavelength, as white by itself has no frequency by itself.  Can somebody explain why really bright pure red, green, or blue LEDs seem white to us and to cameras?  Also, can a bright light ever be pure(eg is it possible to emit a pure red/pure blue/pure green bright light only with wavelengths in the range of that light), or will the inherent brightness of a light force other wavelengths into the light? I just bought a new MTB and am planning to change my previous MTB into a Road Bike.   How do I do it? What kind of parts do I need to change or add or remove?  I am not looking to for a full conversion into specialised road bike. But like the answers are suggesting, I am looking for a bridge between commuter or road bike. My majors concerns to be met are:   Should be fast enough to compete with road racers over short distance Should be light as a road  Should be as close as possible in as cheap as possible. How to avoid the pop up message while downloading an application (.exe) using selenium I am trying to download an application and check if it's downloaded into my local system or not. But when I click the download link I have a popup with Save or Cancel options, which is stopping me from downloading the file. I googled and found some solutions and tried to change the profile of Firefox by adding the below code, but it is not working.  firefoxProfile.setPreference("browser.download.folderList", 2); firefoxProfile.setPreference("browser.download.alertOnEXEOpen", false); firefoxProfile.setPreference("browser.helperApps.neverAsksaveToDisk", "application/x-msexcel,application/excel,application/x-excel,application/excel,application/x-excel,application/excel,application/vnd.ms-excel,application/x-excel,application/x-msexcel"); firefoxProfile.setPreference("browser.download.manager.showWhenStarting", false); firefoxProfile.setPreference("browser.download.manager.focusWhenStarting", false); firefoxProfile.setPreference("browser.helperApps.alwaysAsk.force", false); firefoxProfile.setPreference("browser.download.manager.alertOnEXEOpen", false); firefoxProfile.setPreference("browser.download.manager.closeWhenDone", false); firefoxProfile.setPreference("browser.download.manager.showAlertOnComplete", false); firefoxProfile.setPreference("browser.download.manager.useWindow", false); firefoxProfile.setPreference("browser.download.manager.showWhenStarting", false); firefoxProfile.setPreference("services.sync.prefs.sync.browser.download.manager.showWhenStarting", false);   This is the code I added for setting up Firefox preferences, but I still get the popup. Looking at your network profile, there is no number anywhere in your entire profile that has a sum of all your reputation across the network except for the flair page, which isn't always accurate because it's cached, and isn't exact because it rounds. Yet, there's so much empty space on the profile page.  My simple idea is to list the user's total reputation and badge counts below their Gravatar image like on any normal profile page across the network (keeping the rule of only accounts with over 200 reputation). It would make it incredibly easy to find and I wouldn't have to go search for myself on Area 51 to figure it out. Should I capitalise "or" between examples? On this site, there are often many different options as an answer, for example both with and without the Oxford comma.  When giving multiple options, should I capitalize the word "or" between them?  Option 1:     Eggs, butter and milk are dairy products   Or   Eggs, butter, and milk are dairy products     Option 2:     Eggs, butter and milk are dairy products   or   Eggs, butter, and milk are dairy products     Notice in Option 1 the "or" is capitalised. In Option 2 the "or" isn't. Is there a word for a comment which makes no sense or adds nothing to the current discussion? Stringification of a macro value When I entered the value $$\frac{1}{i}$$ in my calculator, I received the answer as $-i$ whereas I was expecting the answer as $i^{-1}$. Even google calculator shows the same answer (Click  to check it out).  Is there a fault in my calculator or $\frac{1}{i}$ really equals $-i$? If it does then how? Mod of numbers with large exponents [modular order reduction] I've read about Fermat's little theorem and generally how congruence works. But I can't figure out how to work out these two:   $13^{100} \bmod 7$ $7^{100} \bmod 13$   I've also heard of this formula:  $$a \equiv b\pmod n \Rightarrow a^k \equiv b^k \pmod n $$  But I don't see how exactly to use that here, because from $13^1 \bmod 7$ I get 6, and $13^2 \bmod 7$ is 1. I'm unclear as to which one to raise to the kth power here (I'm assuming k = 100?)  Any hints or pointers in the right direction would be great. Combinatorial proof of $\sum_{i = 0}^{n} \binom{i}{r - 1} = \binom{n + 1}{r}$ and then use result to find a formula for $1^2 + 2^2 + \ldots + n^2$ The editor should be able to convert multi-line blocks to lists I am trying to show that $a^{12} \equiv 1 \mod 32760$ for each $a \in \mathbb{Z}$ coprime to $32760$. I have found the prime decomposition $32760 = 2^3 \cdot 3^3 \cdot 5 \cdot 7 \cdot 13$ and determined $\phi(32760)$, where $\phi$ is the Euler's totient function. This gives me that $\phi (32760) = 8640$.   Using Euler's congruence, this gives that $a^{8640} \equiv 1 \mod 32760$, but this is still far from the result I want to show... I also know a consequence of Eulers congruence, which states that $e \equiv e' \mod \phi (n)$ implies that $a^e \equiv a^{e'} \mod n$, but I do not see how to use this...  Any hints would be appreciated.  $\textbf{EDIT:}$ I made a mistake in my primefactorization, it is edited now. TikZ: What EXACTLY does the the |- notation for arrows do? I am currently trying to work out how the perpendicular arrows  work, and I fail.  Taking:  \draw [arrow] (node1) -- node[sloped, above] {Caption} (node1 |- node2.north west);   I suspected that the notation meant: Draw an arrow from node 1, to the north-west corner of  node 2. Make the arrow perpendicular to node 1.  Further attempts to draw arrows told me: No, that's not it. I have sadly failed to figure out what exactly the notation is supposed to be doing though! Is there any "explanation for dummies" that will lead me to understand what exactly    node1 |-   Is supposed to do?  Thanks! Is there a proof from the first principle that for the Lagrangian $L$,    $$L = T\text{(kinetic energy)} - V\text{(potential energy)}$$  in classical mechanics? Assume that Cartesian coordinates are used. Among the combinations, $L = T - nV$, only $n=1$ works. Is there a fundamental reason for it?  On the other hand, the variational principle used in deriving the equations of motion, Euler-Lagrange equation, is general enough (can be used to to find the optimum of any parametrized integral) and does not specify the form of Lagrangian. I appreciate for anyone who gives the  answer, and if possible, the primary source (who published the answer first in the literature).      Notes added on Sept 22: - Both answers are correct as far as I can find. Both answerers were not sure about what I meant by the term I used: 'first principle'. I like to elaborate what I was thinking, not meant to be condescending or anything near to that. Please have a little understanding if the words I use are not well-thought of. - We do science by collecting facts, forming empirical laws, building a theory which generalizes the laws, then we go back to the lab and find if the generalization part can stand up to the verification. Newton's laws are close to the end of empirical laws, meaning that they are easily verified in the lab. These laws are not limited to gravity, but are used mostly under the condition of gravity. When we generalize and express them in Lagrangian or Hamiltonian, they can be used where Newton's laws cannot, for example, on electromagnetism, or any other forces unknown to us. Lagrangian or Hamiltonian and the derived equations of motion are generalizations and more on the theory side, relatively speaking; at least those are a little more theoretical than Newton's laws. We still go to lab to verify these generalizations, but it's somewhat harder to do so, like we have to use Large Hadron Collider. - But here is a new problem, as @Jerry Schirmer pointed out in his comment and I agreed. Lagrangian is great tool if we know its expression. If we don't, then we are at lost. Lagrangian is almost as useless as Newton's laws for a new mysterious force. It's almost as useless but not quite, because we can try and error. We have much better luck to try and error on Lagrangian than on equations of motion. - Oh, variational principle is a 'first principle' in my mind and is used to derive Euler-Lagrange equation. But variational principle does not give a clue about the explicit expression of Lagrangian. This is the point I'm driving at. This is why I'm looking for help, say, in Physics SE. If someone knew the reason why n=1 in L=T-nV, then we could use this reasoning to find out about a mysterious force. It looks like that someone is in the future. Trying to identify pre-1970s short story involving multiple humans absorbed into an alien blob I want to stop having to use sudo everytime I work in /var/www. How can I do that? I simply want to put all of my sites into this directory and work with them without too much pain. Scenario (Ubuntu 16.04):  I compile and run a C program (with -g, I get the traditional Segmentation Fault (core dumped), and then (of course) there is no mythical "core" file to be found. Some digging says to modify /proc/sys/kernel/core_pattern with a command to the effect of: echo '|tee /home/me/my_core_folder/my_core_file' | sudo tee /proc/sys/kernel/core_pattern, and after doing this, I stop getting (core dumped) and start only getting the plain Segmentation Fault. I try things like gdb ./program_object_file.out core.pid which obviously doesn't exist (I was getting desperate), and of course try the plain gdb ./a.out followed by (gdb) core core.pid and variants of the commands where I spam the tab key desperately trying to get auto-completion to get me to where I need to be.  Question:  Is there a generalized way I can get to core dumps? I recognize that every machine that I touch seems to have a Michael Bay's Transformers-esque ability to reconfigure hardware and software such that no device I own can be expected to work normally out-of-the-box. Is there a simple algorithm/recipe I can follow to locate core dumps on my own machine as well as on other peoples' machines? I always find myself tutoring friends on stuff like this after no small amount of  work to get things working for myself and it would be nice to be able to run a command or something to get core files dumped to the directory which the executable was run from... is there any way to do this that should work on most (I would settle for "some") Linux/Unix machines?