This is my first time of using Ubuntu. I am trying to install java jdk-15 in my lap.I applied following steps.  sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-15/bin/java 1 sudo update-alternatives --config java sudo gedit /etc/environment =&gt; I saved the path (JAVA_HOME = &quot;/usr/lib/jvm/jdk-15&quot; ) source /etc/environment ==&gt; this step outputs &quot;JAVA_HOME: command not found&quot;  Why do I get this? Pls help me.
OS: UBUNTU 18.04  I had installed Oracle Java 8 earlier. But decided to switch to open JDK 11. it's successfully installed. java -version openjdk version "11.0.2" 2019-01-15 OpenJDK Runtime Environment (build 11.0.2+9-Ubuntu-3ubuntu118.04.3) OpenJDK 64-Bit Server VM (build 11.0.2+9-Ubuntu-3ubuntu118.04.3, mixed mode, sharing)  Then I set the JAVA_HOME sudo nano /etc/environment  File changes: PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/$ JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64/"  Then executed: source /etc/environment  echo $JAVA_HOME /usr/lib/jvm/java-11-openjdk-amd64/  But the moment I exit the terminal and then launch the terminal again: I get this output:  ▶ echo $JAVA_HOME /usr/lib/jvm/java-8-oracle  which you can see is not what is expected. Please help me out
When / how should I ask about a manuscript's status in review? How to prevent Windows 10 from automatically adding keyboard layouts (i.e. US keyboard) Update: this is a lengthy post, you can     Note: The quick language list refers to the list in the screenshot below, accessible throught the shortcut Win + Space bar  I have two languages for windows spell check in my system, English (United States) and French (Switzerland), but despite both languages being properly configured with "Swiss French" input keyboard, US Keyboard input keeps appearing on this list:    Here's the settings for English (United States) language, you can see the only input is "Swiss French":    Same for Français (Suisse), the only input is "Swiss French":    In the Control Panel, both are also set as Swiss French:    All my settings are set to use "language list":     Here's a few things that I already tried:   I already managed to remove it by some language configuration gymnastics, by adding and removing languages, it always eventually comes back I have already done this:  There's no mention of US Keyboard in my registry settings either:     Please help, I'm desperate, this is my third computer with Windows 10 and they all do the same thing. How to modify a text file? I'm using Python, and would like to insert a string into a text file without deleting or copying the file. How can I do that? I am interested in comparing the computational cost of grid search vs. random search algorithm for hyperparameter tuning. Is random search computationally less expensive then grid search? Is there an article/paper that talks about this topic? Thank you, There is a 2d rotation matrix around point $(0, 0)$ with angle $\theta$.  $$ \left[ \begin{array}{ccc} \cos(\theta) &amp; -\sin(\theta) \\ \sin(\theta) &amp; \cos(\theta) \end{array} \right] $$  Next, there is a 3d rotation matrix around point $(0, 0, 0)$ and unit axis $(u_x, u_y, u_z)$ with angle $\theta$ ().  \begin{bmatrix} \cos \theta +u_x^2 \left(1-\cos \theta\right) &amp; u_x u_y \left(1-\cos \theta\right) - u_z \sin \theta &amp; u_x u_z \left(1-\cos \theta\right) + u_y \sin \theta \\ u_y u_x \left(1-\cos \theta\right) + u_z \sin \theta &amp; \cos \theta + u_y^2\left(1-\cos \theta\right) &amp; u_y u_z \left(1-\cos \theta\right) - u_x \sin \theta \\ u_z u_x \left(1-\cos \theta\right) - u_y \sin \theta &amp; u_z u_y \left(1-\cos \theta\right) + u_x \sin \theta &amp; \cos \theta + u_z^2\left(1-\cos \theta\right)  \end{bmatrix}  How it is possible to generalize rotation matrix on $N$ dimension around zero point and $N-2$ dimensional unit axis with angle $\theta$? How can I block incoming SMS from certain senders? Does this polynomial evaluate to prime number whenever $x$ is a natural number? Emails Per Invocation Still Capped at 100? How can I delete my account? How can I delete my Stack Exchange account(s)? Also,  What happens to my content? Can I request it be deleted as well? What if I'm suspended, rate-limited, or banned from posting questions or answers? What will happen to my votes? Will other users be impacted? Why wasn't my account deleted immediately after the timer expiring? What will happen to my pending bounties and close, reopen, delete, or undelete votes? I want my account deleted on all Stack Exchange sites. How do I do this? Will my profile on chat be removed once I delete my site account?   For more information, see &quot;&quot; in the . Evolutionary chronology - if any, which species have evolved in the last 100 years I heared somewhere, I cannot remember where, that there has not been an evolution observed in our lifetime. In life science class, right at the start, we was doing the usual MRSGREN (how to tell if something is a living organism), and the tutor said that you can also tell something is a living organism if it evolves. So I asked if there has been an observed evolution in our lifetime. She said that there had been many but could not recite any off the top of her head, so the next week she handed me a piece of paper with 8 or so websites that aparrently corroborated her claim. I have not got the paper anymore but I recall there been on there the peppered moth or something. So I set out to look for a chronological list of evolution but could not find an authoritative one. I could only find something on wikipedia that indicated that species have been dying out for the past thousand years, but nothing saying that any have evolved. Recently my wife and I traveled to Italy and before we left we got about 85% of our money in travelers checks and the other 15% we carried on in cash. When we arrived there, no one would take our travelers checks and many places did not accept credit cards. Eventually, we found some currency exchange places that would take the travelers checks and give us Euro's, but at a 7-15% fee, which was not really a very fun surprise.   While I was under the impression that it is safer to use travelers checks, it seems that they were not really accepted (the usual explanation being fraud). So the question is, is it best to just exchange your currency at home and carry all of it with you when you travel or are there other alternatives to carrying cash that are safer and cost effective? What does the operator "<<" mean in C#? Find expected value of $\frac{1}{1+\xi}$ Find expected value of $\frac{1}{1+\xi}$ if $\xi$ has Poisson distribution.  My try:  $$E\left[ \frac{1}{1+\xi}\right]=\sum_{k=0}^{\infty}{x}_{k}{p}_{k}=\sum_{k=0}^{\infty}\frac{1}{k+1}\frac{\lambda^ke^{-\lambda}}{k!}$$  Is it right? How to randomly subset X% of selected points? Find all the values of $w$ ∈ C that satisfy the equation. Best way to draw matchstick pictures I want to draw various matchstick pictures like this:    or like this    or other figures from:   I want to use TikZ for this and have two questions about this:   How do I get the path decoration with the matchsticks? What's the (syntactically) easiest way to draw pictures like this or how would a TikZ expert do this (to be flexible enough to draw such kind of figures but to have an easy syntax)? Consolidate tag wiki excerpt and body contents with regards to suggested edits At the moment, in major part because they are two separate post objects in the system, the excerpt and the body of a tag wiki count as two separate posts with regards to suggested edits in the queue. Mechanically, this is sane, but when it comes to handling the actual queue, it can be confusing. A body edit might consist of little more than a bed of links, which looks bad. But then an excerpt is shown that includes the rest of the data, and since excerpts can be included on the actual wiki page, it makes a lot more sense when they're taken in the same space.  And this is how they are composed, too. The actual edit interface for working on tag wikis has both the excerpt and the body on the same page. In a sense, the excerpt behaves a lot like the "title" of the wiki, if we make a parallel to normal post edits.  Thus, my suggestion (which is to say a suggestion that I repossessed from Robert Cartaino) is that when suggested edits are reviewed for tag wikis, that they be presented in a single unit, treating the excerpt the same as how a title is treated in a question edit. This way, relevant information that is crossed between the two isn't lost because they are reviewed separately. Yesterday, I have received two : Revival, and Self-Learner. However I was only notified of the Revival badge, because apparently the Self-Learner badge is not considered "".  What badges have their notification suppressed if the user has a 200-rep account somewhere on the Stack Exchange network, i.e. they won't trigger a new item in our achievements dialog? CSS customized scroll bar in div Unable to send e-mail. Contact the site administrator if the problem persists When my web form is filled and submitted, I get redirected to a page that says:     Thank you for submitting.   but theres a red warning box there that says:     Unable to send e-mail. Contact the site administrator if the problem persists.   I think its the SMTP server, but I don't know how to fix that.