Variable from concatentation of variables I think this is a rather simple question but, I cant make this work: I have a whole lists of variables eg:  SP60=OLA SP61=BYE SP62=TRT   I want to create a loop to call them in the specific number of the variable so I thought a short solution could be:  for i in {60..62}; do SP=$"SP$i"; echo $SP.txt; done   I was expecting the outcome to be:  OLA.txt BYE.txt TRT.txt   but I get   SP60.txt...   I would like to know if there is a simple way to get this done.
Use a variable reference "inside" another variable I'm sure it is relatively simple, I just don't know how to do it.  #!/usr/bin/ksh set `iostat` myvar=6   I want to something like echo ${$myvar} which i want interpreted as ${$myvar} -> ${6} -> value
ConcurrentModificationException Woes Cannot remove any bluetooth device Infinite Geometric Series Formula Derivation show that  $$\int_{0}^{\infty} \frac {\sin^3(x)}{x^3}dx=\frac{3\pi}{8}$$  using different ways  thanks for all USB-C Charging Speeds / Charger Outputs I own a 2016 Macbook (with the USB-C charging) - at the time and in response to all of the reports of poor cables and poor chargers, I bought a meter so I could see what the throughput of my cables/chargers was. However, having run some tests I'm now not sure what to consider normal / what is harmless to the battery.   For all tests I used an original Apple C-C cable - though was able to replicate with two third party cables I own.  I have the original Apple block charging at 14.3 V / 1.99 A and a third party block that charges the same.  Another third party block which advertises USB PD and 3 A is currently charging at 20 V / 1.43 A  I've done some research online but I can't find any articles that indicate what a normal USB PD output is relative to the devices that connect to it and would appreciate any guidance / assistance.   TL;DR: Have Apple charger which charges at one voltage/amperage. Bought several others advertised at PD which are higher voltage, lower amperage. Not sure what is 'safe', or 'fast', or does least overall damage to battery. Why are certain example URLs like https://site.com/ and https://mysite.com/ blocked from post content? Why is  and  blocked from the post content on the main site? I tried to make a sample URL and I had to use  instead. How did Vader saving Luke turn him to the good side? Couldn't Vader save his son and continue being a Sith Lord? Couldn't he have let Luke go and basically become the Emperor and have the Galaxy to himself? I don't think killing the Emperor to save your son will automatically convert you to the light side. Enlighten me. Information on month old flights Where can I get flight info for a flight a month ago for an insurance claim? Flight stat sites will only show a weeks worth of data. Prove $\int_{a}^{b}{f(x)dx}>0$. Let $f\ge0$ be integrable on $[a,b]$. Let $f$ be continuous on $x_0\in (a,b)$ and let $f(x_0)&gt;0$.   Prove $$\int_{a}^{b}{f(x)dx}&gt;0$$  It is easy to see it, graphically, because $$f\ge 0 \Rightarrow\int_{a}^{b}{f(x)dx}\ge0$$  and if $f&gt;0$ somewhere between $a$ and $b$, then the zone of $F$ between those point is "real" (positive) and $\ne 0$.  My problem is, how do I show it formally?  I would appreciate your help. In school, we just started learning about trigonometry, and I was wondering: is there a way to find the sine, cosine, tangent, cosecant, secant, and cotangent of a single angle without using a calculator?  Sometimes I don't feel right when I can't do things out myself and let a machine do it when I can't.  Or, if you could redirect me to a place that explains how to do it, please do so.  My dad said there isn't, but I just had to make sure.  Thanks. How can I add an item to the 'new' context menu? When I right click anywhere I get an option to add a new file with a specified extension. I would like to add some custom files into this menu, so I can right click and create a new PHP file for instance.  How can I do this? Adding materials to more than one object py2exe - generate single executable file I know that I can use  to make cross-references and hyperlinks clickable.  That makes the clickable areas outlined in fluorescent green, however.  How can I make the green boxes go away? I have a very simple jQuery Datepicker calendar:  $(document).ready(function(){     $("#date_pretty").datepicker({      }); });   and of course in the HTML...  &lt;input type="text" size="10" value="" id="date_pretty"/&gt;   Today's date is nicely highlighted for the user when they bring up the calendar, but how do I get jQuery to pre-populate the textbox itself with today's date on page load, without the user doing anything?  99% of the time, the today's date default will be what they want. Deleting (Erasing) all Data from Failed SanDisk MicroSD Card I've had two 32GB SanDisk MicroSD cards go bad recently.  One I was able to temporarily revive using the kind advice offered in this thread:   When I insert the other into a reader, it registers as 30.6MB (that's MB, not GB).  I've tried all sorts of software and other techniques to revive this card and retrieve the important data off of it (including FindAndMount and TestDisk).  Nothing has worked.  So I'm thinking of returning the card for a refund.  But first, I would like to make it unreadable by someone more skilled than myself.  Is there any way to do this, given that I cannot even format the card or get it to be recognized as more than 30.6MB?  I am looking for a method that does not entail the kind of obvious physical destruction that would jeopardize obtaining a refund from the retailer.  If Costco (where the card was purchased) accepts physically destroyed cards for return, then physical destruction is acceptable (but please have knowledge that they do).  Given two failures, I don't really want to send the card to SanDisk for replacement, because I no longer trust the reliability of their products. How to add System.Windows.Interactivity to project? Proving there are infinitely many pairs of square-full consecutive integers So the question goes like this :  A positive integer $n$ is called square-full if for every prime $p$, $p \, | \, n$ implies $p^2 \, | \, n$, i.e. every prime power factor of $n$ occurs at least at the second power. This is equivalent to saying that there is no prime $p$ such that $p \, \| \, n$.  Show that there are infinitely many consecutive pairs of square-full numbers, i.e. infinitely many $n$ such that $n$ and $n+1$ are square-full.  The context of the question highly suggests that this can be proved by induction and it is the solution that I am looking for. It is not a homework, just something that caught my attention because I couldn't find any natural answer to it... I hope I'm not missing something trivial!  I've tried assuming $n_1, n_2, \dots, n_k$ were the first $n_k$ integers such that $n_i$ and $n_i+1$ are square-full, and then generate some polynomial in those $2k$ integers to get a new couple $n_{k+1}$, $n_{k+1} + 1$ but after a few natural tries I got nothing good out of it. Any ideas? magit: how to diff the same file between two different commits on the same branch? MariaDB won't start on Ubuntu: Can't lock aria control file