Python List - how to evaluate and replace blanks/nulls/spaces in the json string values to some default value?
Does Python have a ternary conditional operator?
Why xargs can't work with tail -f? I want tail -f /var/log/syslog | grep it with pattern "arpwatch" and send every line to myself via jabber: xmpp username@jabber.server using xargs  tail -f /var/log/syslog | grep arpwatch | xargs sendxmpp username@jabber.server   no working.  but tail  /var/log/syslog | grep arpwatch | sendxmpp username@jabber.server   works well.  I think it's some fundamental thing about xargs and tail -f that I don't understand. Allow an edit to notify downvoters: "I think I've fixed the issue now - please check" Inform new users if they can upvote an answer they accepted I surprisingly often stumble upon answers which were accepted but clearly not upvoted by the asker. For example, the answer has not received any upvotes at all or the asker’s vote count is zero. While I acknowledge that , most such cases happen with new users, who have only recently received the privilege to vote and who upvote after a friendly reminder.  Given the anonymity of votes and that I do not check the asker’s profile for every question with an accepted answer I stumbled upon, I assume that there is a huge dark figure for this phenomenon. Also, I naturally most often spot this on my own answers, which makes reminding the asker of their privileges somewhat awkward.  I thus propose that users which accept an answer are reminded by a pop-up that they can upvote it, if:   They haven’t already upvoted it. They have the reputation required for voting. They have cast less than a handful of votes.   I consider the latter criterion to be better than an upper reputation for which the message is displayed, since I know at least one user with several thousand reputation points, who has cast much less upvotes or votes on answers than he has accepted answers on some sites (not that his acceptance rate or general feedback on answers is spectacular). In the original PC release of RollerCoaster Tycoon, if playing in a scenario with a lot of grassland, I would ensure my handymen did not mow the grass as their other services seemed more beneficial to keeping the park tidy, as well as making sure the handymen did not wander off the paths. In the android release, the handymen by default do not mow the grass (that duty by default is set to off).  I know the guests will remark on the scenery and vandalism, but I have not seen anything to suggest that mowing the grass has an effect on the guests or ride construction.  My question is; does mowing the grass have any effects apart from just making the park look tidier? Does allowing it to overgrow have any negative effects? Can a self-complementary graph on 100 vertices have precisely one vertex of degree 50? How can I create or use a global variable in a function?  If I create a global variable in one function, how can I use that global variable in another function? Do I need to store the global variable in a local variable of the function which needs its access? How to get the current directory in a C program? I'm making a C program where I need to get the directory that the program is started from.  This program is written for UNIX computers. I've been looking at opendir() and telldir(), but telldir() returns a off_t (long int), so it really doesn't help me.   How can I get the current path in a string (char array)? The result of ls * , ls ** and ls *** I know using the command ls will list all the directories. But what does the ls * command do ? I used it and it just lists the directories. Does the star in front of ls mean how deep it will list the directories? Show that a positive operator on a complex Hilbert space is self-adjoint Let $(\mathcal{H}, (\cdot, \cdot))$ be a complex Hilbert space, and $A :  \mathcal{H} \to \mathcal{H}$ a positive, bounded operator ($A$ being positive means $(Ax,x) \ge 0$ for all $x \in \mathcal{H}$). Prove that $A$ is self-adjoint. That is, prove that $(Ax,y) = (x, Ay)$ for all $x,y \in \mathcal{H}$. Here's what I have so far. Because $A$ is positive we have $\mathbb{R} \ni (Ax,x) = \overline{(x,Ax)} = (x,Ax)$, all $x \in \mathcal{H}$. Next, I have seen some hints that tell me to apply the polarization identity: $$(x,y) = \frac{1}{4}((\lVert x+y \rVert^2 + \lVert x-y \rVert^2) - i(\lVert x + iy \rVert^2 - \lVert x - iy \rVert^2)),$$ where of course the norm is defined by $\lVert \cdot \rVert^2 = (\cdot, \cdot)$. So my guess is that I need to start with the expressions: $$(Ax,y) = \frac{1}{4}((\lVert Ax+y \rVert^2 + \lVert Ax-y \rVert^2) - i(\lVert Ax + iy \rVert^2 - \lVert Ax - iy \rVert^2)),$$ $$(x,Ay) = \frac{1}{4}((\lVert x+Ay \rVert^2 + \lVert x-Ay \rVert^2) - i(\lVert x + iAy \rVert^2 - \lVert x - iAy \rVert^2)),$$ and somehow show they are equal. But here is where I have gotten stuck. Hints or solutions are greatly appreciated. In the Deadpool movie when Wade his mutant cells get activated, his skin changes so he looks like Freddy Krueger (As Weasel referred too). But he obtains healing abilities and his cancer gets cured because of it. He's become an immortal person which can heal any wound super fast.  What I don't understand is, why doesn't his skin heal so he would look like before? I remember that Francis (or Ajax) said that it's a 'side-effect' of mutating, but why wouldn't it heal when he has a healing ability? The equation $y^2 = x^3 + k$ for $k = (4n-1)^3 - 4m^2$, with $m, n \in \mathbb{N}$ and no prime number that p is congruent to 1 modulo 4 divids m, doesn't have any answer and its proof can be obtained by using quadratic reciprocity law.  Do you know answers of this equation for two or three different values of $k$? In addition, do you know any reference about that? Is there a possibility to search when the embedded txt file was created in the word document? I'm working in Word 2010 and the extension of the document is simple: .doc  It was inserted using the Word options:  Insert -&gt; Object -&gt; Create from file -&gt; Insert as icon   Thank you, I already tried the right click and properties option, but the problem with it, that it shows only the current date for all of the 3 options (created/modified/accessed).           I also tried to get the timestamp but it is inactive when I'm on the txt object.   Sorry not to mention it before: Thank you all of you here for the help and support it is really appreciated. Analogous results to Euler's theorem Fermat's little theorem and its generalization, Euler's theorem holds for pair of relatively prime integers. Are there any analogous results for not relatively prime integers ? Thanks in advance. What are the light blue lines on my imported objects Help! My master database is corrupt, I can't even bring the SQL instance online! What are my options to get my server back up?   I do have a backup of master, but the  asks me to start the instance in single-user mode, which I can't do!  (Note: I'm leaving this question unspecified as to SQL version, so as to be a more widely-applicable reference. There are some similar questions on DBA.SE, but none that involve the server unable to start.) Unmet dependencies unable to fix I'm running ubuntu 14.04. I cannot use software center to install anything, even a local deb package so I have to rely on Terminal.  Recently I was trying to install mysql-server which generated error which I could pin-point was the required version of libstdc++6 . My system had 4.8.x while mysql 5.6 required >=4.9. Trying the usual upgrading process and unsuccessful, I consulted my sys admin, who tried installing the 4.9 package manually(using a local .deb package), which failed as well citing unmet dependencies.   At present, what I have is a system with error saying no new software can be installed.  The sudo apt-get install -f gives following output:  Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... failed. The following packages have unmet dependencies:  libstdc++6 : Depends: gcc-4.9-base (= 4.9.2-10) but 4.9.1-0ubuntu1 is installed  libstdc++6:i386 : Depends: gcc-4.9-base:i386 (= 4.9.2-10) but 4.9.1-0ubuntu1 is installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.   I checked for held packages using  dpkg -l | grep ^h dpkg -l | grep hold   Result: nothing.  Also tried to find the broken package, if any but the file  /var/log/dist-upgrade/apt.log doesn't exist.  So, what should/can I do now. Directory-tree listing in Python How to obtain $f(x)$, if it is known that $f(f(x))=x^2+x$? 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? Jordan form, number of blocks.