How to show a at scheduled command?
What will at actually execute?
Which is the best way to install new hplip versions? Hplip is the software that drives most hp printers. Usually new printers are only supported in newer versions of the software. Canonical doesn't backport new versions packages to older Ubuntu versions, that means that newer drivers are not going to be available in the Software Center of older Ubuntu versions.  As an example yesterday I needed to hook a hp 1005p to a computer running 8.04. I was forced to install a newer hplip than the version available in the repositories. I installed it using the script from the hp page, but I'd like to know other alternatives.  Which is the best (technically, not the easiest) way to install it and why?. I know the so-called textbook definition of unit tests and integration tests.  What I am curious about is when it is time to write unit tests... I will write them to cover as many sets of classes as possible.  For example, if I have a Word class, I will write some unit tests for the Word class.  Then, I begin writing my Sentence class, and when it needs to interact with the Word class, I will often write my unit tests such that they test both Sentence and Word... at least in the places where they interact.  Have these tests essentially become integration tests because they now test the integration of these 2 classes, or is it just a unit test that spans 2 classes?  In general, because of this uncertain line, I will rarely actually write integration tests... or is my using the finished product to see if all the pieces work properly the actual integration tests, even though they are manual and rarely repeated beyond the scope of each individual feature?  Am I misunderstanding integration tests, or is there really just very little difference between integration and unit tests? How can I keep low resolution textures pixelated? How to Disavow Bad Backlinks Automatically? How could Argus Filch clean up the whole castle by himself without magic? Notation of the second derivative - Where does the d go? In school I was taught that we use $\frac{du}{dx}$ as a notation for the first derivative of a function $u(x)$. I was also told that we could use the $d$ just like any variable. After some time we were given the notation for the second derivative and it was explained as follows: $$ \frac{d(\frac{du}{dx})}{dx} = \frac{d^2 u}{dx^2} $$ What I do not get here is, if we can use the $d$ as any variable, I would get the following result: $$ \frac{d(\frac{du}{dx})}{dx} =\frac{ddu}{dx\,dx} = \frac{d^2 u}{d^2 x^2} $$ Apparently it is not the same as the notation we were given. A $d$ is missing. I have done some research on this and found some vague comments about &quot;There are reasons for that, but you do not need to know...&quot; or &quot;That is mainly a  notation issue, but you do not need to know further.&quot; So what I am asking for is: Is this really just a notation thing? If so, does this mean we can actually NOT use d like a variable? If not, where does the $d$ go? I found  related question, but it does not really answer my specific question. So I would not see it as a duplicate, but correct me if my search has not been sufficient and there indeed is a similar question out there already. Maven project with native dependency and copying files how to suppress "chapter" in \chapter (while keeping numbering) The warlock's Thirsting Blade eldritch invocation cannot be normally used with the (non-warlock) class feature Extra Attack, since both feature explicitly say you attack twice instead of once. But it seems to me that you could use both features (if you have them) when using Two-Weapon Fighting.  Assume your character is wielding two light weapons, one of which is your pact weapon. You take the Attack action on your turn to attack twice with your non-pact weapon using your  class feature.  Then, given the Two-Weapon Fighting rules, you use your bonus action to attack once using your pact weapon this time.  The  rules (PHB p. 195) state:     When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand.   But since your have the Thirsting Blade invocation, and you used the Attack action, you get to attack twice with your pact weapon.  The Thirsting Blade  (PHB p. 111) says:     You can attack with your pact weapon twice, instead of once, whenever you take the Attack action on your turn.   Does this combo work within the rules, or is there any interaction I'm not aware of? Understanding dummy (manual or automated) variable creation in GLM What lifetime can be expected of the typical hard disk? Or are there big differences between different types? And does it make a difference if it is used heavily instead of never being connected to system (for example serving as a backup medium)? Prove that a power series $\sum_{n=0}^{\infty}{{a_n}{z^n}}$ which converges for any $z \in \mathbb{N}$, converges for any $z \in \mathbb{C}$. PROBLEM  Prove that a power series $\sum_{n=0}^{\infty}{{a_n}{z^n}}$ which converges for any $z \in \mathbb{N}$, converges for any $z \in \mathbb{C}$.  MY ATTEMPT  Since the power series $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ converges for any $z \in \mathbb{N}$, then $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ can be considered (?) to be a polynomial in $\mathbb{C}$.  Hence, $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ is entire, and therefore continuous in $\mathbb{C}$ (since differentiability implies continuity).  It follows that $$\sum_{n=0}^{\infty}{{a_n}{z^n}}$$ converges for any $z \in \mathbb{C}$.  QUESTION     I am aware that, while I may have (some) ideas for a (general) proof, admittedly there are several grey areas (i.e., gaps) that need to be filled.  Would you be kind enough as to fill in these gaps, by providing useful hints? If an astronaut had stationed in International Space Station for the duration of mission, 17 years, would he be older? Today the NASA International Space Station started the 100000 orbit after 17 years in the space. I just wonder if there were a team of astronauts which were in the Lab for all the duration of last 17 years, how much older they would be due to the combination of Einstein's especial theory of relativity and general theory of relativity?   Here is the link to NASA's youtube video. I'm trying to make airsoft chronograph/chronometer (a device that measures airsoft bullet speed). The idea is to measure time in which bullet is traveling from point A to point B, and then I can calculate bullet speed. Bullet is shot into plastic pipe with diameter of 32mm. I've tried to put on one side IR LED and on the other side phototransistor (BPW 40), both at the start and end of the tube. Something like this:  Blue circles are phototransistors, red circles are IR LEDs and white circles are airsoft bullets. When bullet passes through area where bullet 2  is drawn (just in between IR LED and phototransistor), everyting works perfectly. But when the bullet passes where bullets 1 and 3 are drawn, it isn't detected. That is expected, but unwanted behavior. So my question is: how can I detect bullets regardlessly of it's position ? I've thought about putting IR LEDs and phototransistors around the pipe (not only in one place), like this:  but this solution isn't cheapest: 5 IR LEDs + 5 BPW 40 = cca $12 times 2 (because I need it on both sides of the pipe) = $24. Is there any cheaper solution ? Is BPW 40 good choice for phototransistor ? I don't know which IR LEDs I'm using (and salesman in the store also doesn't know - he told me these are generic ones for remote controllers, like TV or DVD controller). Diameter of the pipe is 32mm and it will be long about 14cm (sensors will be 10cm apart). Diameter of airsoft bullet is 6mm. EDIT: I'll go for my second idea. I just have one more question: is it better to arrange IR emitters and photo transistors this way:  or this way:  Thanks !! How do I bulkify queries for directly or indirectly related records? I have two Xbox 360's, one WiFi and the other wired through the same Linksys E3000 router with DD-WRT (v24-sp2 (04/13/11) std-usb-nas firmware).   Mine (the wired one, though hers has been wired in the past and it didn't appear to help) always seems to be open (green), and hers is either moderate or closed (oj/red)  Even with the original router firmware I've never been able to get both consoles into "open nat" mode, and it makes playing certain games together almost impossible for me and my wife  because we can't seem to get into the same game.   I have uPnP enabled and the DMZ disabled, and some minor port forwarding to allow for a Minecraft server (Ports 25565 and 25566 for a testing copy of the server), but other than that the settings are mainly at their default, on the xbox's and the router.   Are there any settings I can configure to allow this to work properly? Which is the most portable of sed, awk, perl and sh? Proving that an ideal in a PID is maximal if and only if it is generated by an irreducible Multiple registration phases Differentiation - simple case