If this is the wrong place, sorry. It's the best place I could think of to ask.  Goal:  I want to create a PDF with viewable data onscreen. If anyone trys to print it, I want the paper to be blank, have a different message (Thou shall not steal.), all black, whatever.  I don't know how to do this, but firstly I need to know what opensource  software is the best, and robust in features, for attempting this.  I do not want to edit content or drag-and-drop.  I need something that effectively lets me manipulate the actual code of the PDF file.  I will have to muddle through learning PDF programming later.   I know I could use standard security features to protect the PDF from printing.
I typically have two needs:  Scenario A. Change a single PDF page.  In this case I have a PDF but not the original source file used to create the PDF. I don't want to try to recreate the document from scratch. I'd like to open the PDF and change a few things. A good example of this scenario: I was responsible for planning a big event at a campground site, I had a PDF of the site. I wanted to start with that document, highlight some parts, add some labels, remove some parts that weren't relevant.   or   Scenario B. Combine PDFs or extract page(s) from a PDF  This scenario usually arises because I want a single PDF deliverable that is made up of parts that are best created in different programs. In this case I have the source files for all the documents but they don't play well enough together to easily create a single PDF deliverable. For part of it, I may want to use Libre Office Writer. For another page I may want to use Gimp. Still another page I may use Libre Office Calc. I could use Writer as the master document and embed images or the Calc object into that, but for ultimate control, you can't beat separate PDF documents that are then combined.  What are the best tools / processes for editing PDFs in Ubuntu?
How to align content of a div to the bottom Say I have the following CSS and HTML code:    #header {   height: 150px; } &lt;div id="header"&gt;   &lt;h1&gt;Header title&lt;/h1&gt;   Header content (one or multiple lines) &lt;/div&gt;     The header section is fixed height, but the header content may change.  I would like the content of the header to be vertically aligned to the bottom of the header section, so the last line of text "sticks" to the bottom of the header section.  So if there is only one line of text, it would be like:   ----------------------------- | Header title | | | | header content (resulting in one line) -----------------------------   And if there were three lines:   ----------------------------- | Header title | | header content (which is so | much stuff that it perfectly | spans over three lines) -----------------------------   How can this be done in CSS? Minecraft Survival Mode The trigonometric ratios of an angle greater than $90^\circ$ are equal to the supplementary angle's ratios.  I'm just clarifying this, but the ratios don't actually exist for angles greater than $90^\circ$ right? (since by definition these ratios are of a right angle triangle). Is it just mathematical custom to assume the ratios of an angle greater than $90^\circ$ to be equivalent to its supplementary angle's ratios? For convenience? Intutitive meaning behind the formal definition of sufficient statistic? According to the definition of sufficiency, a statistic is sufficient for a parameter if the conditional distribution of $X$ given a value of statistic does not depend upon the parameter.   What I am trying to understand is how does conditional distribution of $X$ not being a function of the parameter fit into the intuitive meaning of sufficiency i.e statistic value holding the same amount of information as that of the respective sample. If A is an infinite set and B is at most countable set, prove that A and $A \cup B$ have the same cardinality I am trying to prove: If A is an infinite set and B is at most countable set, prove that A and $A \cup B$ have the same cardinality.  Set definitions here are from baby Rudin.   Attempt: There are 4 possible cases:  1.A is countable and B is finite.  2.A is countable and B is countable.  3.A is uncountable and B is finite.  4.A is uncountable and B is countable.  Then for each case I need to show that $A \cup B \sim A$. I can prove 1-3, but I am unsure how to prove case 4. And in general, it seems that my proof strategy is inefficient and there exist much faster proof then proof by cases. How to select lenses for outdoor sports photography? I would like to get into sports photography, and would probably want a better telephoto lens so I can get better close up shots.  What other factors should I keep in mind as I make my choice? Does IS (or VR) matter?  What is a good focal length?  I'll probably be shooting mostly little league baseball/softball, church softball leagues, and kids soccer. Can the Dispel Magic spell be Readied to counter an opponent's spell? When playing as a spellcaster, is it valid the use of the Ready action to prepare Dispel Magic to counter a spell cast by an opponent? In the same vein, when declaring said action, do I have to specify which spell slot I will use when Readying the Dispel Magic spell? If that is the case, does this tactic nullify an opponent's spell? I get the impression that this is basically turning Dispel Magic into a spell with a casting time of &quot;1 reaction&quot;. Is my reading of the rules accurate? If $\gcd(a,b)=1$, how can I find the values that $\gcd(a+b,a^2+b^2)$ can possibly take? I can't find a way to use any of the elemental divisibility and gcd theorems to find them. (p → q) ∧ ¬p ⇒ ¬q  I have tried to use the rules of inference in many ways to prove this argument to be valid. However, I cannot seem to find a way to validate the argument, but I am afraid I have missed something.  Using a truth table I find that when p and q is 0, then p → q is 1, ¬p is 1 and ¬q is 1. Would that not make the argument valid?  I apologize in advance if I have misunderstood the whole concept. Any answer would be much appreciated. Thank you How do I make a fully statically linked .exe with Visual Studio Express 2005? My current preferred C++ environment is the free and largely excellent Microsoft Visual Studio 2005 Express edition. From time to time I have sent release .exe files to other people with pleasing results. However recently I made the disturbing discovery that the pleasing results were based on more luck that I would like. Attempting to run one of these programs on an old (2001 vintage, not scrupulously updated) XP box gave me nothing but a nasty "System cannot run x.exe" (or similar) message.  Some googling revealed that with this toolset, even specifying static linking results in a simple hello-world.exe actually relying on extra .dll files (msvcm80.dll etc.). An incredibly elaborate version scheming system (manifest files anyone?) then will not let the .exe run without exactly the right .dll versions. I don't want or need this stuff, I just want an old fashioned self contained .exe that does nothing but lowest common denominator Win32 operations and runs on any old win32 OS.  Does anyone know if its possible to do what I want to do with my existing toolset ?  Thank you. How come unpolarized light does not undergo destructive interference? Why can't we see light travelling from point A to B? Let's say we have a cloud of dust which is a lightyear across and someone shoots a beam of light from point A to B , why it is not possible for an observer far far away to see the light while it travels through the cloud at the speed of light? Remote login with graphical display manager (GDM, LightDM) Is it possible to remotely (via ssh) make a login to GDM? I'll explain a situation in which I'd need this: I'm on my laptop and connect to my desktop via ssh. I realize there are some updates available. I install them all, but I need to reboot the computer. The problem is that once the desktop has rebooted, there will be no GDM session available, since it's necessary to log in. Can I somehow perform the GDM login remotely from my laptop?  Edit: I can't find FreeNX for Maverick, and I haven't been able to configure x11vnc + vncviewer to work. Isn't there an easy way? PHP Change Array Keys Is there a way to change all the numeric keys to &quot;Name&quot; without looping through the array (so a php function)? [     0 =&gt; 'blabla',     1 =&gt; 'blabla',     2 =&gt; 'blblll',     // etc ... ] How to enable the Edit button in Shutter? I am trying to enable the Edit button in Shutter. I installed the application from Ubuntu Software and are using Ubuntu 18.04.  After taking a screenshot the Edit button is disabled. And when hovering the mouse pointer over the button the text "Goo::Canvas/libgoo-canvas-perl needs to be installed for this feature" is shown.    I have tried to install the package libgoocanvas2-perl and restarted the computer, but the edit button is still not enabled:  sudo apt install libgoocanvas2-perl   That is the only package I can find.  Anyone that knows how to fix this? HDMI/Displayport audio control for OS X What's that ship in the opening credits of 'Star Trek: Enterprise'? I was working on a tower and painted my own texture for it. I saved halfway though and took a break. When I returned to my little project, I could paint on the image and it shows up in the material view but not the render. I did everything in my power but still couldn't understand why?  I have used:   Nodes, including mapping and insert UV coordinates. Unwrap UVs Used lights Deleted and replace nodes Deleted and replace Mat Removed image and replace it Reload image Painted on mesh   Even though use blender, I am not a programmer. So I find it really helpful if someone could give me an answer. What happens if I do not honor a futures contract? I have little knowledge about futures contracts. The recent negative price of crude oil spurred my curiosity about this stuff.   I read this post about .  According to this post, when I buy a futures contract, I enter into a contractual agreement to buy some commodity on some future date, and I only need to pay a 2% initial margin.   Suppose the price of the commodity does not fluctuate but I change my mind and decide not to buy the commodity at maturity. What punishment could be exerted on me?   I do not want the 2% initial margin back because that is a little money compared to the real value of the commodity. If there is no extra penalty, it would be unfair for the seller — imagine the seller transports 1000 barrels of crude oil to your front door and you say "I do not need it any more, please take it away, thank you!"  Update: I did more research about this and have more questions.  If I buy a futures contract at $10 and the price of the contract drops to -$37 at the last trading day, at which price should I buy the commodity at the delivery day, $10 or -$37?   There seems not just one contract I enter into when I buy a futures contract: the original futures contract between me and the seller of the commodity(or the exchange?), the contract between me and my brokerage, the contract between the brokerage and the exchange. I'm not clear about the exact entities of each contract and the obligations involved in each contract. The contracts seem contradictory with each other, e.g., my brokerage may forcefully sell my futures contract if my account balance is not enough, which will prevent me from fulfilling the obligations in the futures contract, i.e., receiving the commodity on future date.  If I(or an institutional trader) trade directly (not via a brokerage) with an exchange(does CME accept individual traders?), does the exchange have the rights to forcefully sell my contracts at the last trading day at any price or close my position at the settlement price(say -$37)? If the exchange does so thus letting me own $5,000M to it, is it more justice for me to sue the exchange rather than let the exchange sue me? If I could hold the position, the loss caused by my not executing the delivery/receipt of the commodity may be less than $5,000M. Of course, the loss will be determined by the court, not by the exchange according to the settlement price formed by itself or a few possible conspirators. Is it possible to check a bash script syntax without executing it?  Using Perl, I can run perl -c 'script name'. Is there any equivalent command for bash scripts?