What is the difference between different shells in Ubuntu:  $ cat /etc/shells /bin/sh /bin/dash /bin/bash /bin/rbash
if I write,  #!/bin/bash echo "foo"   or  #!/bin/sh echo "foo"   both yields same. I have seen some scripts starting with #!/bin/sh or #!/bin/bash. Is there any difference between them?
Notebook computer battery says: plugged in but not charging with no further information. Is the battery bad already? My 1.5 year old Dell Studio 15 notebook computer has a battery and I keep it attached to the notebook but 98% of the time I just plug in the power adapter.  Lately when I unplugged the power adapter, the battery was only good for 10 minutes, and a few days ago, when I unplugged the power adapter, the computer simply turned off.  When clicking on the battery icon on Win 7, it says "Plugged in, not charging":    is the battery dead?  Or can Windows 7 have any option to not charge the battery?  It is a Dell Studio 15, I wonder if in such case, it looks like it can be a manufacture's defect, would Dell replace the battery? (if there was a recall, then they probably would, i think).  The notebook is 1.5 year old. Eevee - Light inside a bulb lamp not passing through glass Using Eevee, I'm trying to simulate a light bulb. I have a sphere with glass material and inside it, I have a Point light. But the light is not passing through the glass:  However, if I disable the sphere object, the light is working:   How to make the light inside a bulb lamp pass through glass (using Eevee)? Here my test project: fitch style proof problem regarding rule of inferences Okay I have the following fitch proof almost figured out, from here I know I have to move forth in conlcuding but I don't know what I am missing  (2 premises)  S → (R ∨ P)  P → (¬R → Q)   my work below  new scope assume S   Rule: > elim  R ∨ P  New scope assume R  Q∨R     Rule: V intro  End scope – (new scope assume P)  ¬R → Q         Rule: > Elim  my confusion comes where I go from here  Q∨R            rule Taut Con ??  Goal:├ S → (Q ∨ R) I want to quantify the relationship between two variables, A and B, using mutual information. The way to compute it is by binning the observations (see example Python code below). However, what factors determines what number of bins is reasonable? I need the computation to be fast so I cannot simply use a lot of bins to be on the safe side.  from sklearn.metrics import mutual_info_score  def calc_MI(x, y, bins):     c_xy = np.histogram2d(x, y, bins)[0]     mi = mutual_info_score(None, None, contingency=c_xy)     return mi probability that exactly two accidents happen in any day of a week if 7 accidents happen in a week If 7 accidents happen in a week, what is the probability that exactly 2 accidents happen in any day of the week.  I tried to work it this way.  2 accidents out of 7 can be taken in ${7}\choose{2}$$= 21$.  Now this can happen in any of the 7 days, so we have $7 \times 21$.  Now, the remaining 5 can happen in $6^5$ ways.  So the probability is  $\frac{7\times 21 \times 6^5}{7^7} = \frac{3 \times 6^5}{7^5}$   But this gives me a value greater than 1.   I know I am doing something wrong.  Can anyone help me ? How to demonstrate that there is no all-prime generating polynomial with rational cofficents? How do you clone a Git repository into a specific folder? Executing the command git clone git@github.com:whatever creates a directory in my current folder named whatever, and drops the contents of the Git repository into that folder:  /httpdocs/whatever/public   My problem is that I need the contents of the Git repository cloned into my current directory so that they appear in the proper location for the web server:  /httpdocs/public   I know how to move the files after I've cloned the repository, but this seems to break Git, and I'd like to be able to update just by calling git pull. How can I do this? Closure of $\{\frac{1}{n}\}:=M$ In $\mathbb{R}$ with standard topology the closure of the above set $M$ is $M \cup 0$. I fail showing this by purely topological means. I.e. not using the fact that this holds in the reals as a metric space and deduce it for the induced topology.  I assumed that there exist a closed subset $A$ containing $M$ but not 0. Hence, the complement of $A$ is an open subset containing 0. Does this already yield a contradiction or do I need a different approach?  Could you help me on this? When asking a new question and typing in the title we get a list of similar questions named     Questions that may already have your answer     That suggestions contains posts across all tags. Like the example in the screenshot it returns similar questions for Python, jQuery, SQL, C#, Java, C++, ...  This makes the list less useless unlikely people find a question that already answers theirs. If people actually find a similar question in that list many duplicates could be avoided.  So can tags I entered below the question be considered to update the list? And can the tag textbox maybe put above the question title? Add warning when changing display name The policy on changing one's display name :  only one display name change is allowed every 30 days  However, there is no warning whatsoever when actually changing one's display name.  Thus, it came as quite a bit of a shock to me when I found out today that I might be stuck as &quot;Unicorns are Yummy&quot; on Stack Overflow for the next freakin' month. I would like to recommend that a warning be added to the &quot;Edit Profile&quot; page to warn people. Or, at least make the policy concerning display name changes more obvious. Workaround I was able to change my display name back (phew!) by copying my profile from Meta Stack Overflow. I still think a warning should be implemented, though. What am I doing wrong? Joint Density of sum of random variables! So, I have this question:    And, what I have tried so far is I let $z_1 = \frac{X + Y}{2}$ and let $z_2 = \frac{X - Y}{2}$ to use change of variables for this question. However, when I work this out and plug it into my joint distribution of $X$ and $Y$ above, I end up with the $z_2$ disappearing and only having $z_1$ left in my joint distribution of $z_1$ and $z_2$. So, then when I go to find the marginal for just $z_1$ (which is $\frac{X + Y}{2}$ &lt;- what I am looking for), there is no $z_2$ therefore, integrating wrt to $z_2$, I get $z_2$ just come up (integral of 1). This is an issue because the bounds are from 0 to $\inf$. Obviously, I can't have infinite in my marginal density so what am I doing wrong?   Also, for question 5, I work it out similarly except I let $z_2 = X$ but I just end up with the exact same density as $f_{x,y}$ as seen in question 4 - is that normal? Please help, I been doing this question for a long time trying various dummy transformations.  Also, for question 4, I found the marginals of $x$ and $y$ and realized that the independence consequence (of the product being equal to the joint) is satisfied but using convolution, I get the same issue of my integral coming out to infinite! Thank you for all the help!   EDIT: Am I doing my bounds wrong? the bound for z_2 is from 0 to inf or 0 to z_1? I have 50 servers. I manage them from a central management server on SQL Server 2014 Enterprise Edition. I don't use repository.  I could open a query and get result for each one at the same time. But I want to do it in an automated way, like a job, to collect data from each server and store/handle it locally.  Is this possible and if so, how? How/when to become independent in research as a graduate student? I am in the last months of my MSc and I have done my thesis. I have published some conference papers but most of them were literature reviews.  My MSc thesis is about solving wave equations by means of method of potentials and boundary elements. I am interested in pursuing research in another field (differential equations) but I have no idea how to start any topic that may lead to a journal publication.    By asking this question, I want to understand how a research student, whether a recently graduated MSc student or a PhD student, can start searching for a new research topic and develop some researches based on his own interests. Specially, I would like to know:   To what extent should a graduate student be dependent on faculty members? How can he be more independent and start his own research activities? Is it a good idea that the graduate work on another topic with the faculty member or work independently on a more recent research topic? If the person is in a research group or at the university, is it a good idea or is it ethical that he develop his own research interests, besides to the topics which are being developed in that institute? How should a graduate student manage this and make some progress in the research fields of his own interest? (In particular, sometimes the faculty members are not interested in the topics you are interested in and the person has to start his own research activity.)      And also, if this research is part of his independent research, at the time of publishing what affiliation should be used in the publications. Should it be "Independent Scholar" as mentioned in  or something else? This is important in academic publications, because sometimes, the person is in a research group, but he is publishing a paper as part of his own researches not the things he is doing in that institute; in this case, has he mention that institute's affiliation or use his own one? So please make it clear that how the affiliation would be when the person does research independently in the cases like when he is not working in a research group or he is working with a professor or research group but his publication is output of his own research activities? It is a little unclear. How to add Windows to GRUB I have my encrypted Archlinux installed on my SSD. Now I have one HDD with Windows installed. But in my GRUB just Archlinux is shown (no Wonder, because I just installed Windows on the other HDD, GRUB doesn't know of that by now.).  My Question is, how do I properly add my Windows-HDD to GRUB, so that I can choose which to boot when starting?  I am a little bit afraid of destroying my GRUB so I can't boot my encrypted Archlinux anymore.  Thanks! How can I send an email by Java application using GMail, Yahoo, or Hotmail? Is it possible to send an email from my Java application using a GMail account?  I have configured my company mail server with Java app to send email, but that's not going to cut it when I distribute the application. Answers with any of using Hotmail, Yahoo or GMail are acceptable. I use bash on both my Mac and as my cygwin shell. Overall, I'm quite pleased with it.  My one complaint however is that its TAB completion isn't as good as Windows Command Line TAB completion.   For example, if there are two files with the same prefix, then bash just beeps at me when I try to TAB complete. If I keep nailing TAB, then it will eventually show me a list of potential files.  I definately prefer how Windows will cycle through potential files right on the command line.   Is there a way to get bash to operate similar to Windows Command Line in this regard?  If there isn't (I do not want to switch shells), am I missing something about TAB completion in bash? Is there a more efficient way to use it? A star's collapse can be halted by the  due to the Pauli exclusion principle. In extreme relativistic conditions, a star will continue to collapse regardless of the degeneracy pressure to form a black hole. Does this violate the Pauli exclusion principle? If so, are theorists ok with that? And if it doesn't violate the Pauli exclusion principle, why not? How to use Parameterized MessageFormat with non-Value attributes of JSF components What early-2000s show about dimension hopping has a character who can swap limbs? An earlier question asked about a show that made me think of another one I can't remember.  It was a live action show about exploring different dimensions, and I think the main character was searching for his dad.  I remember seeing it in the US, but I don't know if it was limited to that.  I'm a little fuzzy on the details, but I think the main character could swap his limbs or something like that. Why can Naruto still use Rasenshuriken?