The /etc/crontab on my machine is as follows:  17 *    * * *   root    cd / &amp;&amp; run-parts --report /etc/cron.hourly 25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.daily ) 47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.weekly ) 52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.monthly )   I have two related questions:   Why 17, 25, 47, 52? I get that you might want to stagger the different jobs, but why not stagger them more evenly? Like for instance 0, 15, 30, 45? Why is anacron used for the daily/weekly/monthly commands but not the hourly ones? Are hourly commands more OK to miss? (If I understand correctly, anacron is for if you have an "Every Saturday" command and the computer is down on Saturday, it runs the command on Sunday instead).
To my understanding, this is the default configuration of /etc/crontab:  # m h dom mon dow user  command 17 *    * * *   root    cd / &amp;&amp; run-parts --report /etc/cron.hourly 25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.daily ) 47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.weekly ) 52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / &amp;&amp; run-parts --report /etc/cron.monthly )   Why were these specific times chosen for the default entries?  At first I assumed that they are somewhat randomized on installation to even out the system load, but that doesn't seem to be correct.
View progress towards Announcer, Booster, and Publicist badges I shared a link to a question and now I am wondering whether I am almost going to get an announcer badge.  Can I somehow see which links I shared and how many clicks were on it for the last days?  Update:  Maybe this would be a nice feature. Next to any question you can see who has promoted it the most (number of fresh hits from a referer link) and also the amount of new ip's through search engine's and other referring sites.  Note the progress feature should include the Announcer, Booster, and Publicist badges. If my power supply is 700w, do I need a 700w UPS? if my power supply is 700w, do I need a 700w UPS?  I am running dual 20" dell LCD's, a i7 quad core system with a radion 4870 1gb video card, 2 hard drives. $n$ Lines in the Plane How am I to "[u]se induction to show that $n$ straight lines in the plane divide the plane into $\frac{n^2+n+2}{2}$ regions"? It is assumed here that no two lines are parallel and that no three lines have a common point. Further, this is not a non-Euclidean problem, but I wouldn't mind a discussion on the non-Euclidean nature of the problem.  I was thinking it might be easier to show using the unit sphere.    A GOOD REFERENCE I FOUND THAT WILL BE USEFUL TO ANYONE COMING ACROSS THIS PROBLEM IS Concrete Mathematics, Graham, Knuth, Patashnik pp. 4–8. The Mac editor Latexian has built in methods for compiling using latex+dvips, pdflatex and xelatex.  Furthermore, it assumes bibtex and makeindex to deal with bibliographies and indexes, respectively.  How do I customize Latexian to use, e.g. LuaTeX for compiling or Biber for bibliographies? Using getline(cin, s) after cin Delete files older than X days + I have found the command to delete files older than 5 days in a folder  find /path/to/files* -mtime +5 -exec rm {} \;   But how do I also do this for subdirectories in that folder? Entering U.S. exactly on the day of visa "expiration date" An English book tells me that the following sentence is correct:     This publication is made from paper from sustainable forests.   Shouldn't it be of paper instead? Let $M,N$ be $n \times n$ square matrices over an algebraically closed field with the properties that the trace of both matrices coincides along with all powers of the matrix. More specifically, suppose that $\mathrm{Tr}(M^k) = \mathrm{Tr}(N^k)$ for all $1\leq k \leq n$. The following questions about eigenvalues is then natural and I was thinking it would be an application of Cayley-Hamilton but I am having trouble writing out a proof.  How do we show that $M$ and $N$ have the same eigenvalues?  Added (because this question is now target of many duplicates, it should state its hypotheses properly). Assume that all the mentioned values of $k$ are nonzero in the field considered; in other words either the field is of characteristic $0$, or else its prime characteristic $p$ satisfies $p&gt;n$. Who can see what in my profile? When editing my user profile (name, date of birth, etc.), how can I tell which information can be seen by other users (publicly visible) and what is only used by the system (and how it's used)? Feature request: Add pronouns to usercards? Difference between 'max distance' and 'radius' in Physics.SphereCastAll The current top-voted to  states:     Another one that's not so much a security issue, although it is security-related, is complete and abject failure to grok the difference between hashing a password and encrypting it. Most commonly found in code where the programmer is trying to provide unsafe "Remind me of my password" functionality.   What exactly is this difference? I was always under the impression that hashing was a form of encryption. What is the unsafe functionality the poster is referring to? Why isn't my Minecraft LAN server working? How to Run an app as Administrator without the prompt? When I start SQL Server Management Studio 2008, I get an error that's been around forever and is documented .  One of the suggestions to fix it that actually worked was to start SSMS with Run as Administrator. So I modified the properties of the shortcut to always run it as the administrator.  The only annoyance is that I get a prompt every single time asking whether I really want to do it. Is there a way to tell just this one program (SSMS) to not pop up the prompt, while keeping this behavior for other apps? How to launch the default (native) application for a given file from Java? Can $n!$ be a perfect square when $n$ is an integer greater than $1$? Can $n!$ be a perfect square when $n$ is an integer greater than $1$?  Clearly, when $n$ is prime, $n!$ is not a perfect square because the exponent of $n$ in $n!$ is $1$.  The same goes when $n-1$ is prime, by considering the exponent of $n-1$. What is the answer for a general value of $n$?  (And is it possible, to prove without Bertrand's postulate. Because Bertrands postulate is quite a strong result.) Every word is marked as misspelled in TeXstudio As part of an early quest, my PCs are likely to face off against a wizard.  The problem here is that the stat block for Mage NPCs listed in the Basic Rules has a Challenge Rating of 6, while the PCs are going to be five Level 1s. So, instead of messing with the stat block and risk weakening it too much/too little, I'm choosing to create a Level 1 Wizard PC and use it as an NPC for this quest.  The problem with that is that, as far as I can tell, there aren't any designated rules for assigning either Challenge Ratings or XP values to a PC. So, should I just give the wizard a Challenge Rating equal to his level (and thus have him give 200 xp when killed), or is there a better way to do this?  (This is different from , because he's asking for a way to assign a level to an NPC, while I'm asking for a way to assign an XP value/Challenge Rating to a PC (for use as an NPC). Similar questions, but different.) This is a story that was read on BBC radio about thirty years ago, and this is about as right as I can remember it: The human pilot of a spacecraft is doing some reconnaissance on an alien planet. He crashes but survives. For some reason, no one will know where to look for him. He sees something in the distance that looks like a building of some sort. When he gets there, it seems to be a home. Very much like a human home. There's furniture, but it's strange and uncomfortable . There's food, but it's inedible. There's a faucet but what comes out of it seems more like acid. Everything looks as though it should be right, but it's not. He leaves the house, wanders and after a few days is desperate for water. But there isn't any water anywhere. He's close to death, crawling on the ground and then something happens. There are cracks in the soil and there appears to be water bubbling up from perhaps some underground stream. The water revives him. He goes back to the house and tries the food again. It's delicious and he eats enough to gain back his strength. Then he decides to try the water again. It's pure and wonderful. He takes a shower and the last line of the story is how refreshing the water is on his skin and something about him lifting his tail.