With QGIS 2.12.3, I have two projected EPSG:2927 point shapefiles, A and B.  I would like to create a selection of A points that are within 100 meters of any B point.  This is easy in Arc, using the Select by Location tool with the search distance option.    I am aware of two Select by Location tools in QGIS (Vector -> Research Tools -> Select by Location and the Spatial Query plugin).  However, neither has a search distance option.  In summary, how to do a QGIS Select by Location with a search distance?
I have a point layer in QGIS. Each point represents a tree and each tree has information about its height as an attribute. I would like to build a query/expression to select all those trees that have an other tree higher than 7 meters within their 20-meter-buffer (20 meter radius).  I managed to do this "manually" by creating a 20-meter-buffer around all trees higher than 7 meters (after the selection of the trees higher than 7 meters) and then selected the ones within the buffer but I was wondering if its possible with a query/expression.  (maybe with a bit more complex one)  Unfortunately I do not have PostGIS so this should be done with Select by expression or Query Builder if possible.  (It would be also helpful to know if it's simply impossible)
I have heard that most spam filters use a reverse DNS lookup on the originating IP address of the sending SMTP server (or something like that) as part of the verification process.  I want to make sure my emails will pass this check.  How exactly can I verify that my emails are OK?  In researching it, I've noticed that if I look at the header of a valid email message coming from Gmail, I will see something like this:  Received: from mail-pz0-f185.google.com (mail-pz0-f185.google.com [209.85.222.185])         by mx.google.com with ESMTP id 10si2346996pxi.164.2009.07.22.22.26.19;         Wed, 22 Jul 2009 22:26:19 -0700 (PDT)   When I do an nslookup on 209.85.222.18, it responds with mail-pz0-f185.google.com, which is what I would expect.  If it responded with a different domain, then I assume that would indicate a problem and it would fail the check.  Is this what the reverse DNS lookup is all about or am I barking up the wrong tree? Is spacetime discrete or continuous? How to disable system beep for non-privileged user I want to test in a script whether a hostname resolves to something other than 127.0.0.1 as a pre-flight test for an install script. The tools I know (dig, nslookup) specifically query DNS. In my situation a correct entry in /etc/hosts is a valid configuration. So the question is:  Is there a dig-like tool, ideally already on the system, that does the full name-resolution process via nsswitch.conf, like (for example) ping does?  dig my-test-server-that-only-exists-in-etc-hosts    returns NXDOMAIN. Find $a$ such that $(x+a)(x+1991)+1=(x+b)(x+c)$ with $a,b,c\in\Bbb Z$ Find all integer values of $a$ such that the quadratic expression $(x+a)(x+1991)+1$ can be factored as a product $(x+b)(x+c)$ where b and c are integers.   I tried to do it by comparing the two expressions but I can't proceed. How do I boot to a command line interface instead of a GUI? Hi I have ubuntu server 10.04 installed and I also installed the following:  su aptitude install xorg xfce4 aptitude install &lt;name of GUI browser, I use firefox&gt; aptitude install gedit aptitude install gnome-terminal   Now when I restart the system it goes to the GUI login, what I am really after is a system that loads the CLI by default and then I can use startx to load the GUI when really necessary. I am trying to learn CLI but I would like to retain access to the GUI for now. And, how can I switch between CLI and GUI anytime? My Bash Prompt is currently setting the xterm titlebar using the following sequence:  PS1='\033]0;\u@\h&gt;\w\007'   Is there an easy way to display the current command in the titlebar. For example, if I am tailing a file using tail -f foo.log, I want my titlebar to say tail -f foo.log. Can a magus with a high BAB cast two spells or attack and cast, with their full attack action? Suppose you are a level 10 Magus or something similar. (Something with a decent BAB progression and spellcasting abilities) When you hit +6/+1, can you cast a spell, then attack, vice-versa, or simply case two spells? Everywhere I look I can't get a clear answer. How can I add an empty directory to a Git repository? Migrate from a virtual machine (VM) to a physical system Solutions to the equation $ze^{a-z}=1$ Let $a \in \mathbb{R}, a&gt;1,$ and consider the equation $$ze^{a-z}=1$$ How many solutions does this equation have in the unit disk, and how many of those solutions are real?   My attempt to solve was to use the Argument Principle on the function $f(z)=ze^{a-z}-1$, in hopes of recovering the number of zeroes that way. The integral I attempted to compute for this was $$\int_{|z|=1} \frac{e^{a-z}-ze^{a-z}}{ze^{a-z}-1}dz=\int_{|z|=1}\frac{1-z}{z-e^{z-a}}dz$$  I do not know how to proceed from here, as the $e^{z-a}$ in the denominator seems problematic. Thanks for your help! C# Mono - Low Level Keyboard Hook I'm using code that I found on the .  The only problem is it uses external DLL calls that don't work in mono.  I was wondering if anyone knew of a way to accomplish the same thing as that code, but will run in both Windows using .net, and Linux using mono?  Edit:  Clarifying what I'm trying to do: I'm making a .  The program sits in the system tray and when the user presses the hot-key, it will pop up all the gadgets.  So the program doesn't have focus, so typically it won't catch any keystrokes, so I'm using the low-level keyboard hook and I hook the two keys that the user defines as the hot-keys.  But I'm using a Windows DLL call for that, which doesn't work in Linux using mono.  So I'm wondering if there's a way to do the same thing, but will run in Linux using mono? Anyone know a simple method to swap the background color of a webpage using JavaScript? I hear a lot of talk about apparmor, I want to know the following:    What is apparmor? How does apparmor work? Does this sentence have too many subjunctives? Reproject GeoJSON from EPSG:3857 to EPSG:4326 Can we get an indication comments are hidden between the comments? How do I know if I'm working on a Virtual Machine or not? Is there a way to know if the Windows machine I'm working on is virtual or physical? (I'm connecting with RDP to the machine. If it's a virtual machine it is working and handled by VMWare). $$  \lim_{n\to\infty} n^{1/2} \int_{0}^{1} \frac{1}{(1+x^2)^n}\mathrm{d}x=0 $$  Is my answer correct? But I am not sure of method by which I have done. I want to make an arena where mobs will fight each other and a player can bet on one side or the other. For example: There are 2 skeletons in dyed armor; red and blue. Each color representing a team. When they spawn I want them to fight each and then when one dies I want it to announce which team is the winner and give the player the "money" due. I'm just not sure how to get the skeletons to attack each other without a player instigating it.