I want to run a server with user-written scripts. But these scripts should only use one core (which should be the one with the lowest usage because there will be many concurrent scripts). Also I need to limit time and RAM for them.  Is there an easy way to achieve this, or do I need to check which core has the lowest usage and assign it to it via e.g. ulimit?
I need to externally limit a process/session to a certain number of cores.  Are there any other possibilities than CPU affinity (I don't like the need to specify the actual cores) and cgroups (hard to integrate into our project)?
Why do objects sometimes fall on their own? Can I control voltage of USB data pins? I just bought a 5 volt dual relay module for my arduino.  But now that I have it I was wondering if there is any way that I could control it directly from USB.    The pinout of the module is GND  ONE  TWO  VOC This would make it really easy to just connect a USB cable to it. Assuming I did that is there any way to send 5 volt through the USB Data+ and Data-?  Thank you Selection by attribute string with wildcard as part of name in ArcGIS Desktop? I have an attribute field in my file geodatabase (GDB) where I'm trying to select all records that contain an underbar in the string field.  The issue is that the underbar is considered a SQL wildcard on its own.  To illustrate: I need all data similar to "ID" = '42W_42_42E' or "ID" = '31A_31'  Using "ID" LIKE '%_%' returns all records, which isn't helpful.  The perfect solution would simply return a count on the number of records with the underbar in their ID attribute. A clarification in a limit While reading this  I do not understand that how can we claim that there exist a polynomial with the properties, even if it exist then how is it same for the function and the inverse. why ls reports a huge file and du does not? I several days ago somewhere read that category and tag pages should be noindexed. But later on somewhere else, I read that, they only increase rank for search term, but overall traffic decreases- said one from his experience.  So, if I just concern about traffic, not about individual search term that much, should I make those category and tag pages as indexed to google? I am confused which is the best to do.  Thanks in advance.  Regards Rana NULL values inside NOT IN clause How were the solar masses and distance of the GW150914 merger event calculated from the signal? Browser back leaves page after going fullscreen in stack snippet Opening a Stack Snippet in full screen should use history.pushState() to add an entry to the browser history stack. Clicking back will then close the snippet rather than leave the page completely. Why is a finite integral domain always field? This is how I'm approaching it: let $R$ be a finite integral domain and I'm trying to show every element in $R$ has an inverse:   let $R-\{0\}=\{x_1,x_2,\ldots,x_k\}$,  then as $R$ is closed under multiplication $\prod_{n=1}^k\ x_i=x_j$,  therefore by canceling $x_j$ we get $x_1x_2\cdots x_{j-1}x_{j+1}\cdots x_k=1 $,  by commuting any of these elements to the front we find an inverse for first term, e.g. for $x_m$ we have $x_m(x_1\cdots x_{m-1}x_{m+1}\cdots x_{j-1}x_{j+1}\cdots x_k)=1$, where $(x_m)^{-1}=x_1\cdots x_{m-1}x_{m+1}\cdots x_{j-1}x_{j+1}\cdots x_k$.   As far as I can see this is correct, so we have found inverses for all $x_i\in R$ apart from $x_j$ if I am right so far. How would we find $(x_{j})^{-1}$? If $[G' : G'']\leq p^2$, then $G'$ is abelian. Execute a program at login I'm running Arch-Linux ARM on a Raspberry Pi.  My project goal is to have a barcode scanner attached to the Pi that forwards the scanned messages to a server in a LAN.  To harden the system against power outages etc. and minimize required user interaction, I wish to set it up so that a certain user is logged in automatically at startup (done and works) and a specific program is to be run at startup (done and works but not as intended).  I've done this so far by adding  exec mono scannerSoftware.exe 127.0.0.1 1234 randomString   to /home/certainUser/.bash_profile so it gets executed only once even when I'm switching back and forth to root (in contrast to bashrc).    The particular problem I am having: When I launch the system, it works as intended (login as certainUser, starting scannerSoftware.exe); BUT if I want to switch users and hit Ctrl+C, it restarts the login process, logging certainUser in again and running the program again => back to where I came from.  My guess as to why this happens is that the sys detects "login not complete, better start it again".  I could circumvent this by spamming Ctrl+C right around the login so that I practically interrupted it. Of course, this is not good practice. Suffice it to say it is not practical at all.  My question: How can I set it up so the program gets executed AFTER login is complete so that Ctrl+C'ing out brings me to a normal bash prompt as certainUser instead of beginning the endless login-cycle?  EDIT: I'm not using any graphical interface or such, only commandline (bash on tty), because when done the system won't even have a display. macOS: Is there a way to show an image constantly on screen (like a watermark)? I'm looking for a very simple way to add a watermark to my screen which should be shown whatever I'm doing, is it during a Zoom call, or is it when giving a presentation, or similar (I don't necessarily need it to show during fullscreen mode). The reason is that I want to record my screen using QuickTime Player, and the watermark should be on the video. I know that there are many post-production tools that offer adding watermarks, but I don't want to do any post-production, I want to have everything on screen while recording already. (I also know that there are screen recorders which offer placing a watermark to the end result. I'd rather also avoid using another screen recording software, but if I don't find any other way to do it, then I'm open to a simple, non-pricy alternative to QuickTime Player.) Exact Duplicate:        I was reading an article on MSDN where I found a mention to google-fu. It says, “To search for C++ delimeters and code snippets is going to take a little Google-fu on the reader's part.” what does google-fu mean? What is Reflection in Java Can anyone explain? Origin of the dot and cross product? Most questions usually just relate to what these can be used for, that's fairly obvious to me since I've been programming 3D games/simulations for a while, but I've never really understood the inner workings of them... I could get the cross product equation as a determinant of a carefully-constructed matrix,   but what I want to ask is... How did the dot and cross product come to be? When were they "invented"? Some detailed proofs? Did someone say: "Hey, wouldn't it be nice if we could construct a way to calculate a vector that is perpendicular to two given operands?"  Basically, how/why do they work?  I would appreciate explanations, links to other explanations, other web resources... I've been searching the Internet lately for explanations, but most of them are on how to use it and nothing that really gives substance to it. Can I switch the User-Agent header for only a single web site? Displaying multiple fields as labels if one field is null in QGIS? I am having some issues trying to show multiple fields for a single label in QGIS. In QGIS2.6, attempting to display labels for a feature consisting of multiple fields results in an empty label if one of the fields is null. So for example, in the label expression dialog:  concat("Temp Site",'\n',"Notes",'\n',"Function")   will function normally unless one of the fields is null, then it results in no label being shown. Using the '||' operator instead in the expression dialog also results in the same behaviour:  "Temp Site" || '\n'  ||  "Notes" || '\n'  ||  "Function"   Is there a way to display the labels even if one of the fields is null? How to interleave the lines of two or more files? I have tried to get the 2 files output in a single file.  I have tried below command:  cat file1 file2   but here file2 data is appending to file1.  What I need is file1 1st line followed by file2 first line, and file1 second line followed by file2 second line etc.  Can anybody tell me how to do this in a simple way? Can I watch the progress of a `sync` operation? I've copied a large file to a USB disk mounted on a Linux system with async. This returns to a command prompt relatively quickly, but when I type sync, of course, it all has to go to disk, and that takes a long time.  I understand that it's going to be slow, but is there somewhere where I can watch a counter go down to zero? Watching buffers in top doesn't help.