I'm trying to grep for a instance "test" in /etc/oratab. But wanted to display only the line that doesn't begin with a comment. Below are the lines from /etc/oratab file:  #test:/u01/appl/oracle/test/db/tech_st/12.1.0.2:N test:/b001/app/oracle/testrac/db/tech_st/12.1.0.2:N         # line added by Agent   This is how I'm trying to get the details I'm interested in (placed the below in a shell script:  DB_NAME=test env_var=`cat /etc/oratab |grep $DB_NAME |grep -v '#' |cut -d":" -f 2` echo $env_var   The problem here is, as the 2nd line also has a comment at its end, it is also being ignored.   Please help.  Regards, RA
I try to search for lines that start with "1" using   ls -1 | grep ^1*   but it returns lines that do not start with 1. What I am missing here?
Compute $\int\limits_{-\infty}^{\infty}\frac{1}{(1+x^2)^{n+1}}dx$ via residue calculus. Let $\Gamma_R$ be the semicircle of radius $R$ in the upper half plane. Then,  \begin{align} \int\limits_{-\infty}^{\infty}\frac{1}{(1+x^2)^{n+1}}dx  &amp;= \lim_{R\to \infty}\int_{\Gamma_R}\frac{1}{(1+z^2)^{n+1}}dz \\ &amp;= 2\pi i \operatorname{Res}\left(\frac{1}{(1+z^2)^{n+1}},i\right) \end{align} The pole of the function at $i$ is of order $n+1$, so the residue is computed by \begin{align} \operatorname{Res}\left(\frac{1}{(1+z^2)^{n+1}},i\right) &amp;= \frac{1}{n!}\lim_{z\to i}\frac{d^n}{dz^n}\left(\frac{1}{(z+i)^{n+1}}\right) \\ &amp;= \frac{1}{n!}\lim_{z\to i}(-1)^n\frac{(n+1)(n+2)\cdots(2n+1)}{(z+i)^{2n+1}} \\ &amp;=\frac{(2n+1)!}{i2^{2n+1}(n!)^2} \end{align} Hence, $$\int_{-\infty}^{\infty}\frac{1}{(1+x^2)^{n+1}}dx = \pi\frac{(2n+1)!}{2^{2n}(n!)^2}$$ The answer provided is $\frac{1\cdot 3\cdot 5\cdots(2n-1)}{2\cdot 4\cdot 6\cdots (2n)}\pi$. How do I manipulate my answer to obtain this answer? Do lens hoods need to be matched to focal length? Is it true that not all generic lens hoods work on all lenses (provided the filter diameter matches, of course)? I read that the focal length plays a role in it - but I cannot find such readings on any lens hoods I see available online. File transfer using sockets (C#) - received file doesn't contain full data I understand the idea of a focal length for a single lens, i e the distance from the lens to the point at which parallel rays of light converge. However, in the case of a photographic lens with multiple lens elements, where exactly is the focal length of the lens as a whole measured from? How many points in RSA, such that $m^e = m \bmod n$ For every RSA-cryptosystem, there exist some messages $m$, for which it holds that $m^e \equiv m \pmod n$ As to the question, how many such messages exist, this question has already been asked and answered here:  However, I do only understand the answer up to a certain point Suppose that $n$ is only 1 prime. Then it holds that the number of unconcealable messages is $\gcd(e-1, p-1)+1$ This is because in $m^e \equiv m \pmod  p$ , either $m = 0$ or $m \not= 0$. In the latter case $m$ can be expressed as $g^t$, where $g$ is a Generator in $\mathbb{Z_p}$ $g^{t*e} \equiv g^t \pmod p$ $g^{t(e-1) \bmod p -1 } \equiv g^{0 \bmod p -1} \pmod p$ $t(e-1) \equiv 0 \pmod {p-1} $ has exactly $\gcd(e-1, p-1)$  solutions, so the total number of unconcealable messages is, together with $m=0$ , $\gcd(e-1, p-1)+1$ When we now look at real RSA, which has two prime factors in its modulus, it holds that the number of unconcealable messages is $(\gcd(e-1, p-1)+1)\cdot(\gcd(e-1, q-1)+1)$ Why is that so? I suppose it has to do with CRT, but I just cant understand why. Bash/Korn shell script edited on Windows throws error '...^M: not found' Evaluate:  $$\lim_{x\to{0}}\bigg(\frac{2}{x^3}.(\arcsin{x}-\arctan{x})\bigg)^{2/x^2}$$  I can just expand $\arcsin{x}$ and $\arctan{x}$ using their taylor expansions, but is there any other method? Unable to change payment information to NONE in iOS Appstore Ever since adding an iTunes gift card to my account, I'm getting verification requests like crazy. I can't even download free apps. It takes me to my payment info and when I try to select none, I continually get a message under the payment info that says "you must verify your payment info to continue"  I don't want a credit card on file and would really like the none option to work. My ID shows I still have iTunes credit. How to switch from Resident visa to Tourist visa status in the Schengen area? Create line graph with ggplot2, using time periods as x-variable How to export debug logs? I spend my days waiting on the Force.com Console and it makes me crazy, I have a pretty nice machine and it still chokes on the details sometimes.  Anyways, I saw  had given a  and is presenting again this year Dreamforce '12.  However, it seems like they're presentation is targeted at using their product, or for that matter others like it (, ) on Heroku, and not really targeting APEX/VisualForce development!  Is this the case? Are there any better solutions out there for reviewing logs?  Are there any APIs that allow you to export your debug logs out of SFDC programatically? Or has anyone even tried to tackle this? How can something happen when time does not exist? I saw  hosted by Stephen Hawkins.  And if I didn't get it wrong, it says that there was no time before the big bang, time was created there.  So how can anything happen when there is no time (eg: the creation of time and the universe)? Is this what he calls a 'singularity'? Which I could think like this: when there is no time nothing can happen, except during this singularity.  Of course I don't know of a law that says 'when there is no time nothing can happen..', I just came up with it, as something intuitive. Definition of $\mathbb{R}^\infty$ How to render world position pass How do I suppress the whitespace above an equation block at the page top? How do I suppress the whitespace above the equation block at the page top ? It is added to the top margin, and I don't want that to happen. I know that \abovedisplayshortskip controls this for the whole document, but how can I change this for this particular equation block and NOT for any others ? Negative vspace doesn't work.  \documentclass[pdftex,12pt,a4paper,english,dutch,leqno]{article} \usepackage[top=1cm,right=1cm,bottom=1cm,left=1.5cm,noheadfoot]{geometry}         \usepackage{babel} \usepackage{amsmath} \usepackage{amssymb} \usepackage{empheq}  \begin{document}  \abovedisplayskip=6pt \abovedisplayshortskip=3pt % This should NOT be changed \belowdisplayskip=6pt \belowdisplayshortskip=3pt  \begin{equation*} \left.\begin{array}{r} a_{31}'=a_{11}\cdot a_{31}-a_{31}\cdot a_{11}=0\\ a_{32}'=a_{11}\cdot a_{32}-a_{31}\cdot a_{12}\\ a_{33}'=a_{11}\cdot a_{33}-a_{31}\cdot a_{13}\\ a_{34}'=a_{11}\cdot a_{34}-a_{31}\cdot a_{14}\\ b_{3}'=a_{11}\cdot b_{3}-a_{31}\cdot b_{1} \end{array}\!\!\right\} \Longrightarrow\; \begin{matrix*}[l] \text{Pseudo-code :}\\ a_{11}\cdot b_{3}-a_{31}\cdot b_{1}\mapsto b_{3}\text{.}\\ \forall\;i\in\{4,3,2,1\} : a_{11}\cdot a_{3i}-a_{31}\cdot a_{1i}\mapsto a_{3i}\text{.} \end{matrix*} \end{equation*}  \end{document} I am looking to sell and buy a house. But with the current market being as crazy as it is (houses are selling fast for sometimes 150,000 over asking), I'm afraid if we sell first, we could be stuck without a new house. Or stuck settling on or over-paying for something and wishing we never sold at all. I'm wondering if it's possible to buy first. What is the best way to secure my next house before selling my current house without getting locked into a B-lender mortgage or risking too much?  I know there would be some risk putting an offer on a new house without knowing how much the current house will sell for, or the risk we don't sell the current house before the new house closes. I'm also afraid conditional offers will not be considered. Are there any other options?  (We do have a mortgage on the current house, but because the market has gone up so much there is also a good chunk of equity.) How to get scroll position from GridView? Let $F$ be a field. Why does $F[x]$ have infinitely many irreducible elements?   For the case F has characteristic 0  Then x-a is irreducible for all a $\in F$ since x satisfies no non-trivial relations in F.  Obviously this argument fails for a finite field since there are only finitely many a to choose from.  So how may I construct irreducible polynomials in a finite field?  I figure it must involve higher powers of x, maybe $x^n-a$ ? Is $n^{th}$ root of $2$ an irrational number? Possible Duplicate:          Will every $n^{th}$ root of $2$ be an irrational number? If yes, how can I prove that? What are the functions that are their own inverse?  (thus functions where $ f(f(x)) = x $ for a large domain)  I always thought there were only 4:  $f(x) = x , f(x) = -x , f(x) = \frac {1}{x} $ and $ f(x) = \frac {-1}{x} $   Later I heard about a fifth one     $$f(x) = \ln\left(\frac {e^x+1}{e^x-1}\right) $$ (for $x &gt; 0$)  This made me wonder are there more? What are conditions that apply to all these functions to get more, etc.