How do I save the output of a command to a file?  Is there a way without using any software? I would like to know how.
I want to write batch or something, that will write output of top into a file on login.  I did top &gt;&gt; output-file, but it contains some strange character!  Can somebody give a simple tutorial about how to write batch file in Linux?
Does the Symmetric difference operator define a group on the powerset of a set? $G$ is the set of all subsets of a set $A$, under the operation of $\triangle\;$: Symmetric Difference of sets.  $A$ has at least two different elements.  I need to check if this is a group, and if it does to show if the group is abelian and/or finite.  Associativity - easy from Symmetric Difference. Identity element - empty group. Inverse element - each element is inverse to itself. Am I right?  abelian? finite? How can I increase the JVM memory? In Bash, when to alias, when to script, and when to write a function? In Einstein's General Relativity, do the space-time dimensions curve according to the positions of stars, planets, and masses? If an effect would prevent a spell from doing damage, does it continue to prevent that damage after the spell changes zones? Anthony casts , targeting Nathan's .  Nathan casts and resolves , choosing to 1) prevent all damage that would be dealt by Searing Blood this turn and 2) put a +1/+1 counter on Elvish Mystic.  Searing Blood resolves, deals no damage, and goes to the graveyard.  Anthony casts and resolves  to kill Elvish Mystic.  Searing Blood triggers from the graveyard, because Elvish Mystic died. Does the prevention effect created by Dromoka's command still apply to it after it changes zones? In other words, will Searing Blood deal 3 damage to Nathan? How can I take a photo using a slow shutter speed without it being overexposed? When I try to take a picture using a slow shutter speed in daylight it is overexposed. How can I change the settings so it isn't overexposed? Ubuntu 18.04: switch back to /etc/network/interfaces Starting sometime around Ubuntu 18.04, the Ubuntu devs stopped using the classic /etc/init.d/networking and /etc/network/interfaces method of configuring the network and switched to some thing called . This has made a lot of people very angry and been widely regarded as a bad move. Is it possible to remove netplan and use the correct /etc/network/interfaces method for configuring the network? Prove that subsequence converges to limsup Given a sequence of real numbers, $\{ x_n \}_{n=1}^{\infty}$, let $\alpha =$ limsup$x_n$ and $\beta = $ liminf$x_n$.   Prove that there exists a subsequence $\{ x_{n_k}\}$ that converges to $\alpha$ as $k \rightarrow \infty$.   Not sure how to start this without since I'm not given that the subsequence is bounded.. Does anyone know the (specific) reasons that it is recommended that old LTS server users wait until the point release to upgrade?  Is it just a matter of bug fixes and waiting for improved stability for production servers, or is there something more fundamental than that? To better describe the above problem, whenever I start up my Ubuntu/Windows 10 Machine and select Ubuntu, whenever the machine tries to start the GNOME Desktop Environment, it says it started it successfully. however, I never get a graphical desktop environment to use. I can fix this by logging into tty3 and typing gnome-session but I don't really want to do that as, for some reason, that skips login. Can anyone help? Ubuntu missing from HP boot menu I have a HP laptop with Windows 8.1 and Ubuntu 14.04 dual booted. I used to use F9 key to enter boot menu and chose Ubuntu and then GRUB would appear where I would chose Ubuntu again. This was working fine all this while. Either a hardware change or a Windows update has caused the Ubuntu option to go missing from the boot menu itself.  How do I fix this and boot into Ubuntu again? Is it acceptable to change colors on a logo to make it fit a website's theme? I have a few payment brand images that need to go in the footer of a website, the footer is very dark grey, to the point where making the logos grey-scale wouldn't be much of a good idea, especially as we still need the logos to stand out.  For example I took the following logo:   And changed it to fit with our very dominant red theme:    Is this good in terms of the user's perspective? Is this legal or misrepresenting the brand? If so is completely changing a logo to white acceptable for dark backgrounds? Show Google results along with related questions A significant number of downvotes are given to questions whose askers didn't first check Google. This seems to be closely related to downvotes from asking a question with duplicates in the "Related Questions" field. How about also showing Google's "I'm feeling lucky," or some other results, in the Related Questions to help out with that?   EDIT: to clarify, I'm not talking about questions with answers on Stack Overflow, but rather questions with easy solutions available via Google. Here's a question just like that: I have located where the error message originates from it is in  line number 221. As I have only a single nvidia driver installed I suspect it is is the same issue. I am not a developer but looking at the code preceding this line I can see the statement.  const char *glob_pattern = "/usr/lib/nvidia-[1-9][0-9][0-9]"  this will pick up nvidia-352/ nvidia-361/ and nvidia-361-prime/ ? on my PC. Books for starting with analysis I am interested in self-studying real analysis, and I was wondering which textbook I should pick up. I know all high school mathematics, I have read  (I did most of the exercises).  I have completed a computational calculus course which covered everything up to and including integration by parts (including the substitution method and Riemann sums) I am currently considering:    From what I have heard this is not very well suited for self-study and that while the exercises are extremely difficult, if you take the time they are worth the effort.    I have heard that while Spivak explains proofs in much more detail than Principles, it doesn't cover all of the material in the latter.    I don't know much about this. I have only seen some comments saying that it is an excellent introduction to analysis.    Extra clarification edit: I would prefer a book not to ''dumb down'' the material, something that would not hold my hand through every step, something that would force me to fill in the gaps myself instead of explaining every single step. That is why I am currently leaning towards Rudin, but before I decide I would still like some information on the book by Apostol. Prove that $\cos\theta$ is root of equation $8x^3-4x^2-4x+1=0$, given $\theta=\frac{\pi}{7}$.   I put $\cos\theta$ in equation, but couldn't show the left-hand side to be zero. Is there a way to output for Print. I want to save in a higher DPI than the default 72dpi say 300dpi that's a good quality for printed pieces. I tried downloading an add-on but don't know if I am installing it correctly it isn't showing up but the bar in python is green. I'm using the 2.69 version of Blender. If no such feature exists what size have any of you found best for print quality. Thank you I've just set up a new machine with Ubuntu Oneiric 11.10 and then run  apt-get update apt-get upgrade apt-get install git   Now if I run git --version it tells me I have git version 1.7.5.4 but on my local machine I have the much newer git version 1.7.9.2  I know I can install from source to get the newest version, but I thought that it was a good idea to use the package manager as much as possible to keep everything standardized.  So is it possible to use apt-get to get a newer version of git, and what is the right way to do it? Don't heavier objects actually fall faster because they exert their own gravity? The common understanding is that, setting air resistance aside, all objects dropped to Earth fall at the same rate. This is often demonstrated through the thought experiment of cutting a large object in half. The halves clearly can't then fall more slowly just by being sliced in two.  However, I believe the answer is that when two objects fall together, attached or not, they do "fall" faster than an object of less mass alone does. This is because not only does the Earth accelerate the objects toward itself but the objects also accelerate the Earth toward themselves. Considering the formula: $$ F_{\text{g}} = \frac{G m_1 m_2}{d^2} $$  Given $F = ma$ thus $a = F/m$, we note that the mass of the small object doesn't seem to matter as when calculating acceleration the force is divided by the $m$ term, its mass. However, this overlooks that the force is actually applied to both objects, not just to the smaller one. The acceleration on the second, larger object is found by dividing $F$, in turn, by the larger object's mass. The two objects' acceleration vectors are exactly opposite, so closing acceleration is the sum of the two:  $$ a_{\text{closing}} = \frac{F}{m_1} + \frac{F}{m_2} $$  Since the Earth is extremely massive compared to everyday objects, the acceleration imparted on the object by the Earth will radically dominate the equation. As the Earth is $\sim 5.972 \times {10}^{24} \, \mathrm{kg} ,$ a falling object of $5.972 \, \mathrm{kg}$ (just over 13 pounds) would accelerate the Earth about $\frac{1}{{10}^{24}}$ as much, which is one part in a trillion trillion.  Of course in everyday situations, we can for all practical purposes treat objects as falling at the same rate because of this negligible difference—which our instruments probably couldn't even detect. But I'm hoping not for a discussion of practicality or what's measurable or observable, but what we think is actually happening.  Am I right or wrong?  What really clinched this for me was considering dropping a small Moon-massed object close to the Earth and a small Earth-massed object close to the Moon. This made me realize that falling isn't one object moving toward some fixed frame of reference, but that the Earth is just another object, and thus "falling" consists of multiple objects mutually attracting in space. Integrate $\int \frac{dx}{\sqrt{-ax^2 + bx +c}} $