Changing from user to superuser
'sudo su -' vs 'sudo -i' vs 'sudo /bin/bash' - when does it matter which is used, or does it matter at all?
This was an assertion made in our textbook but I have no idea how to show that either statement is true.  Also would like to show that that $\mathbb{Q}(\sqrt{2})$ is strictly larger than $\mathbb{Q}$, which was the second part of the assertion. Why can't humans throw objects at bullet speed when the force involved seems so small? The force that propels a bullet should at least be similar in intensity to the force experienced as recoil and the force exerted on the target. But these forces seem really low (the equivalent of a shove).  If all it takes to make a small object achieve bullet speed is the equivalent of a shove, why can't humans throw objects at these speeds? Is there a way to include an entire text file as a string in a C program at compile-time?  something like:   file.txt:  This is a little text file  main.c:  #include &lt;stdio.h&gt; int main(void) {    #blackmagicinclude("file.txt", content)    /*    equiv: char[] content = "This is\na little\ntext file";    */    printf("%s", content); }    obtaining a little program that prints on stdout "This is a little text file"  At the moment I used an hackish python script, but it's butt-ugly and limited to only one variable name, can you tell me another way to do it? Is $D_n$, the dihedral group of order $2n$, isomorphic to a subgroup of $S_n$ ( symmetric group of $n$ letters) for all $n&gt;2$? Why does my iPad keep asking for my iCloud password? I keep receiving an iCloud pop-up message to insert my iCloud password every time i switch on my iPad and I'm unable to do anything on it, inserting the password doesn't help. What should I do? Is "aren't I" correct grammar? Energy-momentum tensor transformation Is it acceptable to use "Just wondering" as a question? I often find myself writing sentences such as: "I am wondering if the landlord replied to you yet?"  And I always end up removing the question mark and rephrasing the sentence. In speech it is easy to inflect such a sentence so as to infer that it is a question, but in reality "I am wondering" is a statement and I feel it should not have a question mark when written down.  So is it acceptable to use "I am wondering" as a question? Why does $PSL(2,\mathbb C)\cong PGL(2,\mathbb C)$ but $PSL(2,\mathbb R) \not\cong PGL(2,\mathbb R)$? Why does $PSL(2,\mathbb C)\cong PGL(2,\mathbb C)$ but $PSL(2,\mathbb R) \not\cong PGL(2,\mathbb R)$? What's the difference between package managers? What are the differences between apt-get, aptitude, and synaptic, and which one is the recommended choice for normal day-to-day package management?  This is a basic question, but I think it'd be good information to have on the site, and besides I am relatively new to Ubuntu so I could use an expert explanation. Intuition behind using complementary CDF to compute expectation for nonnegative random variables I've read the proof for why $\int_0^\infty P(X &gt;x)dx=E[X]$ for nonnegative random variables (located ) and understand its mechanics, but I'm having trouble understanding the intuition behind this formula or why it should be the case at all. Does anyone have any insight on this? I bet I'm missing something obvious. ART has better performance and better battery life on paper at least.  Should I consider switching to it on my moto g? What are the results I can expect? What precautions should I take? Is it easy to turn back to dalvik? Don't count non-printing characters, HTML comments or other content not displayed toward minimum character requirements A follow-up to , and an extension of .   shows that it is possible to circumvent minimum character requirements using null bytes.  Can we exclude such non-printing characters as ASCII NULL and other control characters from counting toward minimum character requirements?  Edit: Users have demonstrated that , unmatched or invalid HTML tags, and other content that is not displayed after Markdown parsing can be used to bypass such requirements as well.  Can we cover this case as well, except for links? Plotting layer given with Longitudes [0 360] to [-180 180]? I have a world map in correct Longitudes from -180° to 180°. Additionally, I have a shapefile of data from South America, which shows at 290° instead of -70°. How can I reproject it using QGIS? Convergence of a sequence implies convergence of the norm of the sequence If $\langle X_n \rangle$ is a sequence in $\mathbb R^n$ then $\lim\limits_{n\to \infty}X_n=A$. Show that $\lim\limits_{n\to \infty} \| X_n \| = \| A \|$ .   My thought process, $\| X_i \|= (\sum_{i=1}^n x_i^2)^{(1/2)}$ therefore be the multiplicative property of limits $x_i^2 = a_i^2$. Therefore the limit of norm of the components is equivalent to the limit of the corresponding limit of each component of the sequence. How can I find a saved Wi-Fi password? I have an Android phone which is connected to a secured Wi-Fi hotspot.  How can I find out the password of the hotspot from the phone? Prove that $(x^2 + x+2)$ ideal is a maximal ideal in $F_3[x]$ ring.  I know the theorem about factor rings and fields     B ideal from A ring is maximal iff A/B factor-ring is a field   How can I use the theorem here? Is there consensus in the field of statistics that one book is the absolute best source and completely covering every aspect of GLM - detailing everything from estimation to inference? When quoting a quotation, how do you handle the double quotes? Assume there is original source text:     This restaurant is amazing with "delicious lasagna" and great service.   Make sure you go 6-7pm for the quietest times.   I want to quote "delicious lasagna" but not sure how to handle the outer double quotes.  If I was quoting more than just that quotation (e.g. is amazing with "delicious lasagna" and great service) I'd just do:     "...is amazing with 'delicious lasagna' and great service."   However, when quoting just that quotation, it looks like:     "'delicious lasagna'"   Is this the correct way or is there something better? Making Change for a Dollar (and other number partitioning problems) I was trying to solve a problem similar to the "how many ways are there to make change for a dollar" problem.  I ran across a  that said I could use a generating function similar to the one quoted below:     The answer to our problem (293) is the   coefficient of $x^{100}$ in the reciprocal   of the following:      $(1-x)(1-x^5)(1-x^{10})(1-x^{25})(1-x^{50})(1-x^{100})$   But I must be missing something, as I can't figure out how they get from that to $293$. Any help on this would be appreciated.