I create and keep the following automated backup files e.g.:   fruits_29-12-2013.gz fruits_30-12-2013.gz fruits_31-12-2013.gz sweets_01-12-2013.gz sweets_02-12-2013.gz sweets_03-12-2013.gz   .. actually many of them in the same folder.  (But then it's a problem to house keeping them manually but I still have to. Because after a month, all are taken up the disk space. So I need to clean up the latest files, accordingly.)  How to automatically DELETE the OLDEST file with name starts with fruits?  (Then I'll put that script/command in the daily crons.)
Is there a command to delete all the files in a directory that haven't been modified in N days?  I need to clean up some old logs.
My mom has an android tablet and she doesn't even know what a site is, her e-mail, or even the password of her facebook account. She's an average user. The internet is facebook in her eyes. She has no need for apps or anything, it's just, only, precisely facebook. All is facebook.  How can I completely disable installing apps in android so they can't be installed in any way or form, I mean, not by URL, not by clicking, not by app store, not even by another program. Just disable the entire thing altogether.  Doesn't need to be safe, have locks, passwords etc. I'm not trying to secure the device from intruders, attackers or robbers, I'm trying to secure it from its very own user.  Please help. I just had to remove two anti-virus apps that were opening adware pages when she tried to open facebook lite, and that's obviously a no-go, apps which she "had not installed." Clearly there's some voodoo going on here for them to just popup, or maybe she just did it unknowingly, but none of that's relevant. How can you just disable installs so this couldn't ever happen again? "SELECT *" why is it an antipattern On multiple questions here and on stack overflow i saw people saying in the comments and answers that select * from table is almost always an antipattern without any explaination why. Althrough I can sort of deduce why it is an antipattern. I may be looking over a detail that someone else with better understanding of the issue noticed.  So here is my question, why people say that select * is an antipattern. How can I install a Canon printer or scanner driver? Poisson / exponential distribution Next weekend you will be participating in 12km cross country race on a mountain.The average time between  two successive wild animal sightings on the mountain is reported to be 5 minutes  (a) What is the probability that you see at least one wild animal in the 11th minute of the     race given that you will see 3 wild animals since the start of the race?  (b) What is the probability that it will take more than a quarter of a hour before you see a wild animal after ten minutes of running?  Now I have attempted (a) , but I don't know whether my thinking is correct. (b) on the other hand makes little sense to me.  My attempt:  (a)$ X~ Poisson(\frac{1}{5})$ and $Y~Exponential(\frac{1}{5})$  $Pr(X&gt;4) = Pr(X&gt;1)$  (I am thinking that this is some variation of the memoryless property)  $Pr(X&gt;1) =Pr(Y&lt;1)$  $Pr(Y&lt;1)= 1 - (e^{(\frac{-1}{5})})$  Perhaps, I was a bit to vague in my attempt of (a). So here goes my attempt of(b).From my understanding of the question , it is asking what it the probability that the time between events(in this case animal sightings) is more than 25 minutes given you have been running for ten minutes  Now from what I know the fact that you have been running ten minutes is irrelevant this is due to memory-less property of the exponential  distribution   so without further ado  I present my attempt at (b)   let $X $ be exponentially distributed random variable with $\lambda = 1/5$  then  $Pr(X &gt;15) = 1 - Pr(X &lt;= 15)$ Is there a package to secure rendered pdf with a password? Is there a package and command that can secure rendered pdf with a password? $$\overline{z}=z^n$$ where $n\in \mathbb{N}$   So I have started with moving the polar representation as the expression is in the n-th power  $$rcis(-\theta)=r^ncis(n\theta)$$   I can not multiply both sides in $r^{(-n)}$ as $n\in \mathbb{N}$ how should I continue? What do I say to make a new line when using voice recognition? I've found I can make punctuation happen by saying "comma", or "period", but I can't find the word for new line.  I tried "paragraph", and "line break", but it just prints those words. Simple Linq query has duplicated join against same table? 2 separate lights on two separate switches on one line - issue Is there a word that means "a span of six months"? That is, I want to connote a stretch of time that lasts half a year, not an event that happens every six months. EDIT: Summary  I think I've found the best definition of what I want thanks to the discussion with @M. Tibbits:  When I open or refresh the SO, I get a notification of new activities that are of interest to me. Today these are (hard-coded): answers to my questions and comments addressed to me. I want a bit more control over it, that's all.     Yes, I've read  and , but I think I add new (good :) ) reasons for re-asking it:  The first question was answered before this so handy "inbox" notification feature was implemented. So now using favorites for "watching" a question is wrong, IMHO, for 2 reasons:   it splits essentially the same functionality (of getting notified when there is an activity you are interested in) between 2 very different user interfaces it's cumbersome - I need to: 1) add question to favorites; 2) click on my profile dropdown; 3) click on the "favorites" line; 4) see all my favorites with recent activity; 5) select the one I watch; 6) repeat this process occasionally to get updates; and 7) possibly remove the question from favorites at the end. All this as opposed to this little red button when there are news.   Favorites are different in nature that watching. I add a question to Favorites when I find the answers useful to me in my work, so I may want to have it handy in the future. By watching an interesting question I will be able to decide whether I want it in faviorites, after I see the answers.  EDIT: I see that I was not clear enough.  I want to add a question to Favorites when:   it has some good answers the question and answers are relevant in my work I want to keep them handy as my long-term (persistent) knowledge base   I want to watch a question for short while (matter of days/weeks) when:   it is interesting / relevant I want to follow it to see what are the answers. Then I can decide whether I want it in my favorites   As you see, the main differentiators are good answers and long/short term. For short-term, automatic notification is better.  Bottom line, all I ask is "watch this question" checkbox (which may expire after say a week if there is a need to free resources) How to show $\alpha\int_a^cf(x)dx+\beta \int_c^b f(x)dx =0$ means $f(x)=0$ everywhere $?$ Question :  Let $$f\ :\ [a,b]\rightarrow \mathbb R$$   be  continuous . And  there  exist  constants  $\alpha$  $\beta$  such  that  $\forall c\in [a,b]$  $$\alpha \int_a^c f(x)dx +\beta \int_c^b f(x)dx =0 $$   Prove  that  $f=0$  allover  $[a,b]$.  Attempt :(not much useful )   Since  the  equation  holds  for  all  $c\in [a,b]$   , if  take  $c=a$  then  we  have $$\beta \int_a^b f(x)dx =0 $$  And  taking  $c=b$  we  get $$\alpha \int_a^b f(x)dx=0 $$  See  if  both  $\alpha=0$  and  $\beta=0$  hold  then  there  is  nothing  to  do . If  only  one  of  them  is  $0$   and  the  other  is  non-zero  then  from  the  last  two  equations  we  get $$\int_a^b f(x)dx =0 $$ and  this  does   not  ensure   $f$'s  being  identically  $0$  on  $[a,b]$ (for  example : $f(x)=sin x$  and $a=0$,$b=2\pi $ ) .   So  our  only  possibility  is  that  both $\alpha \neq 0$  and $\beta \neq 0$  must  hold .  Now  I  cannot  proceed  any  further  from  this  point . Please  give  me  some   hints  as  to  what  to  do  next .  Thaanks. iPhone Apps section not showing up in iTunes Values of the limit $\lim\limits_{x\to+\infty}\left(\sqrt{(x+a)(x+b)}-x\right)$ Hi I have a question regarding finding the values of limit for the following question.  Let $a, b \in \mathbb R$. Find the limit $$\lim_{x\to+\infty}\left(\sqrt{(x+a)(x+b)}-x\right)$$ Downcasting in Java Upcasting is allowed in Java, however downcasting gives a compile error.   The compile error can be removed by adding a cast but would anyway break at the runtime.   In this case why Java allows downcasting if it cannot be executed at the runtime? Is there any practical use for this concept?   public class demo {   public static void main(String a[]) {       B b = (B) new A(); // compiles with the cast,                           // but runtime exception - java.lang.ClassCastException   } }  class A {   public void draw() {     System.out.println("1");   }    public void draw1() {     System.out.println("2");   } }  class B extends A {   public void draw() {     System.out.println("3");   }   public void draw2() {     System.out.println("4");   } } Is it shell portable to run a command on the same line after variable assignment? Is there any standard that covers the portability of running a command after variable assignment on the same line?  APPLE="cider" echo hi   How portable is something like that? Where will it work and where won't it?   Also: my shell scripts start with #!/bin/sh if that makes any difference. Why use "need not" instead of "do not need to"? The header of  states:     High-level languages need not be slower than low-level ones.     Why use need not instead of do not need? What does it mean? Also, why no to before be? What software can I use to view epub documents? What software can I use to view .epub documents? How can you programmatically tell an HTML SELECT to drop down (for example, due to mouseover)? How can you programmatically tell an HTML select to drop down (for example, due to mouseover)? There are many beings that have very big powers. There are beings that are worshipped as gods (Asgardians; and I would lump Azazel into that as well since Marvel seems to imply that he's - while a mutant - someone people consider to be "Devil"). There are mutants whose power would clearly have been considered as "god like" by people worshipping Greek or other polytheistic pantheons where the threshold to what made you a god was pretty low.  But are there any actual major "Gods" in Marvel universe?  Since there are many different definition of what a "god" is, the one that is pertinent to this question:   Power wise, being able to create Universe(s); e.g. gods more in a sense of Christianity/Judaism scale rather than "Pan" or "Hestia" in Greek pantheon who merely have some limited supernatural powers over small domain of natural events. Effectively immortal, at least excluding specific exotic attacks. Origin-wise, be "supernatural", not merely a human mutant or a powerful alien with advanced technology. Desire/demand/like followers' worship or prayers.