Read the output of a command into a variable
Storing output of command in shell variable
How to test hypothesis of no group differences? What to look for in a starter-level off-camera flash? I have zero experience with flash and want to learn how to use it from zero, for example by following the Strobist blog.  What are the absolutely necessary specifications I should look for when shopping for a flash, and can I find something in a price range less than $200.00?  My camera is a Nikon DSLR. Batch jobs error emails report:      The transaction log for database 'WebDB' is full.   No, it isn't. Its 90% free. The transaction log backups run normally. My hardware guy tells me the hardware is running perfectly, with plenty of space. SQL Server 2008 SP3, but not R2.  I'm a developer, we no longer have a DBA. So it falls to me to try and fix this. What are "first class" objects? When are objects or something else said to be "first class" in a given programming language, and why? In what do they differ from languages where they are not?  EDIT. When one says "everything is an object" (like in Python), does he indeed mean that "everything is first-class"? Here is my question:  Is a homeomorphism, that is, a continuos function whose inverse function is also continuous, always bijective? Understanding complete separation for logistic regression Why does logistic regression not converge for a linearly separable data set?   For linear separable data sets the model parameters go to infinity when mimizing the error function (according to Bishop2006, Pattern recognition and machine learning, section 4.3.2). I don't understand why. It must be connected to setting the score function, i.e. the derivative of the error function, to zero.  The error function is given by $E(\mathbf{w})$ as shown in the figure below. Where $\mathbf{t}$ is the target variable vector of the training set and $\mathbf{w}$ the parameter / coefficient vector. The posterior probabiltiy for class 1 is given by  $$y(n) = p(C_1|\mathbf{x}_n) = \sigma(\mathbf{w}'\mathbf{x}_n).$$ Where sigma is the logistic sigmoid function and $\mathbf{x}_n$ is the feature vector for instance $n$ including the predictors.     My second question to logistic regression is if the to posterior probabilities $p(C_1|\mathbf{x}_n)$ and $p(C_2|\mathbf{x}_n)$ sum to one? I currently have a valid Schengen tourist visa that expires next year, issued by the French Consulate in Saudi Arabia.   I am going to a 60-day study abroad program in Italy and they require a student visa. I went to the Italian Consulate in Boston and they asked me to go to the French Consulate and cancel my visa. However, the French Consulate said that I needed to contact the French Embassy in Saudi to cancel the visa.   How can I cancel my tourist visa if I am currently in the United States? My Italian student visa application is due tomorrow morning. Are there solutions that can limit the CPU usage of a process? I am using an old laptop and doing heavy processing that needs high CPU usage for a long time (~30mins - 2hours). When the process puts heavy load on CPU for a long time, CPU overheats and computer shuts down. I don't want to use a cooler/stand because I am carrying this laptop around and working outside home.  Is there a way/application that I can limit CPU usage of a process in Windows?  Note: Setting the priority of the process from task manager does not work.  Note 2: Fans are clean. Cosine of the sum of two solutions of trigonometric equation $a\cos \theta + b\sin \theta = c$ Question: If $\alpha$ and $\beta$ are the solutions of $a\cos \theta + b\sin \theta = c$, then show that: $$\cos (\alpha + \beta) = \frac{a^2 - b^2}{a^2 + b^2}$$  No idea how to even approach the problem. I tried taking two equations, by substituting $\alpha$ and $\beta$ in place of $\theta$ in the equation and manipulating them, but that didn't get me anywhere. Please help! I just installed a new Ubuntu Server 18.04. I set my hostname hostnamectl set-hostname ****.openbayou.biz and I set /etc/hosts:  127.0.0.1 localhost [ip address] ****.openbayou.biz hostname # The following lines are desirable for IPv6 capable hosts [ip6 address] *****.openbayou.biz hostname ::1     localhost ip6-localhost ip6-loopback ff02::1 ip6-allnodes ff02::2 ip6-allrouters   I also installed OSSEC to monitor for new files, errors and changes to my server and I'm now getting these alerts:  Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-  0001, retrying transaction with reduced feature level UDP.`   It's now repeating itself:  systemd-resolved[3195]: message repeated 4 times: [ Server returned error  NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction  with reduced feature level UDP.]   I've looked online for a solution and nobody is reporting this issue. When studying systems of linear equations, it's nice to remind people that the last column of the coefficient matrix holds the constants.  This is often done in books by putting a vertical line between the last column and the next to last column.  What is a good way to do this in LaTex? Impact of changing instances' passwords As part of a security policy, the company I work for has given me the task of changing the sa's and SQL Server Agent service accounts' passwords for several instances.  What's the possible impact of doing this? Is there anything in particular I should watch out for? Is there any whitepaper, guide or even blog post about this kind of task? What kind of 'backup' plan should I have in place in case anything goes wrong?  Any guidance is appreciated. Where do ultra-high-energy cosmic rays come from? Physicists have detected an amazing variety of energetic phenomena in the universe, including beams of particles of unexpectedly high energy but of unknown origin. In laboratory accelerators, we can produce beams of energetic particles, but the energy of these cosmic rays far exceeds any energies produced on Earth. So my question is, from where do these  come from? Is it safe to put hot food in the fridge? I heard that putting really warm food in the fridge right after cooking it is not the right thing to do. It might cause bacterial growth? Is this true? As generally acknowledged TeX offers superb formatting capabilities for math in an automated fashion. Nevertheless there are some areas with clear deficiencies  that one either has to accept or manually improve on a case by case basis.  One of the biggies in that respect is TeX's handling of sub-formulas (i.e., material inside a brace group, e.g., and index, but also any group on top-level). TeX sets such sub-formulas always in natural width even if the whole formula is subject to severe stretching or shrinking otherwise. As an example, consider the following (not very sensible) example:  \documentclass{article}  \newlength\x  \begin{document}  \newcommand\formula{$ a+\mathbf{b+c}+d+e+f = \sum_{i=1}^{n-x-y-z} x_{i+j}$}  \settowidth\x{\formula}  \hbox to \x{\formula}    % natural width  \addtolength\x{-20pt}  \hbox to \x{\formula}   % now shrink it a lot  \addtolength\x{100pt}  \hbox to \x{\formula}   % now stretch a lot in the opposite direction  \end{document}   The formula here has a number of obvious sub-formulas in the subscripts and superscript, but for illustration I also added a sub-formula via \mathbf. Of course the usage of \mathbf in this way is wrong!!! (it should not be applied to several symbols), but I'm sure you would find this in documents. In any case just {b+c} would have had the same effect here. Now what do you think happens if we run this?  This:    As one can see the naturally "boxed" sub-formulas are very wrong the moment the rest of the formula is subject to stretching or shrinking.  Until recently no TeX engine successor addressed this issue. With LuaTeX opening up a lot of the internals of TeX I had some hope that this would be different. However, upon studying the manual my conclusion is that this area (sor far it least) has not been addressed (or considered).  As far as I can see the only way something could be done in LuaTeX about this issue would be to  use the mlist_to_hlist callback. However, this would really mean replacing the full math typesetting algorithm, which of course could be a way to solve the problem but ... but what is needed is not that (as 99% of this algorithm is next to perfect) but to add support to not simply box sub-formulas at their natural width.  So long text ... here is the short question:   Is this analysis correct, or did I overlook something? And in case anybody knows: are there plans to look into the sub-formula issue and provide support for it eventually? (it is not listed on the "to-dos" for math)    In case somebody wonders that I talk about "this sub-formula issue" as if it is something like a known thing ... it is, it was already raised way back in  which at the time a some thorough (if not say heated) discussions. Page Object Model or External property file for Selenium Object Repository I am a beginner in Selenium WebDriver (Java with TestNg). I'm trying to create a framework of my own.  My question here is what would be the better option to store my objects (basically all the webelements of my website under test), Page Object Model or External Property file? Why? Is there a better method than those? Please help. Number of preimages of a group element under a homomorphism. How to extract a floating number from a string Active Directory: Is it required that the "A" record for a domain point to a Domain Controller? Is starting a group with 5 newbies (DM included) possible? Some friends and I want to start playing D&amp;D (5e), but none of us, DM included (not me) have played before to any great extent. The DM and I have some cursory experience with 4e, but have never been able to play to any great extent. Is this advisable, or should we play with existing groups first? We live in a relatively remote area, making it hard to find experienced players.