I'm new to ubuntu, does it come with a firewall installed or will I have to install one, if so which one is best.
Does Ubuntu come with a preinstalled or automatic firewall? If not, do I need one?   I've read some articles about the advantages of Linux over other operating systems about security (no need to have antivirus, ...) but would like to be sure.
What is the appropriate statistical test when calculating the busiest day of the week? We have 10 years of data and Monday is the busiest (most visits to the hospital) on average. If we wanted to assess whether that is true and report a p-value, what is the appropriate statistic?   We believe the answer is chi-square as we found a peer-reviewed medical article from the Annals of Emergency Medicine (highest circulating journal for that specialty) that used chi-square for this very calculation.   If chi-square is appropriate, what values do we use for observed and expected values for chi-square? One approach would be to list all the values for Monday as observed values, or all the means for Mondays averaged across a month, or all the means for Mondays averaged across a year.  If there were no busiest or least busy days, we would assume that the visits would be the same every day of the week. That means our "expected values" for Chi-Square would be the mean of the visits for any given week. Combinations of selecting $n$ objects with $k$ different types Suppose that I am buying cakes for a party. There are $k$ different types and I intend to buy a total of $n$ cakes. How many different combinations of cakes could I possibly bring to the party? What is the difference between #include  and #include "filename"? Which one is correct to say: "It's me" or "It's I"? I was taught at school that the following expression is not grammatically correct:  Who is there? It's me.  The correct one is:  Who is there? It's I.  Can you let me know which one is accurate? Keeping chunks loaded in minecraft I have built an iron farm somewhere far away from my actual spawn chunks in my single player world. In hindsight, this was a dumb idea, but I can't exactly change it anymore. I'd like to keep the thing running all the time, so I'm looking for a way to keep the chunks loaded.  I'm running minecraft 1.12.1, is it possible at the moment? I have looked at some chunk loader mods, but chicken chunk loader hasn't been updated yet, and the others simply didn't work.  I have tried moving the spawn chunks, but that hasn't done anything either.  Edit: I have worked this out with IronAnvil, and it ended up being a render setting in optifine which didn't load them correctly somehow. It has been working fine after I reset my optifine settings to default. Because of a former error in our ASP.Net application, created by my predecessor and undiscovered for a long time, thousands of wrong URLs where created dynamically. The normal user did not notice it, but Google followed these links and crawled itself through these incorrect URLs, creating more and more wrong links.  To make it clearer, consider the url     example.com/folder   should create the link     example.com/folder/subfolder   but was creating     example.com/subfolder   instead. Because of bad url rewriting, this was accepted and by default showed the index page for any unknown url, creating more and more links like this.     example.com/subfolder/subfolder/....   The problem is resolved by now, but now I have thousands of 404 errors listed in the Google Webmaster Tools, which got discovered 1 or 2 years ago, and more keep coming up.  Unfortunately the links do not follow a common pattern that I could deny for crawling in the robots.txt.  Is there anything I can do to stop google from trying out those very old links and remove the already listed 404s from Webmaster Tools? UMP of product functor I want to search for what += means, but Google won't return any documents.  Also when I come across some PHP code I don't understand I can't search for the keywords as written.  How can I search for these special characters or include these special characters in a search. INT vs Unique-Identifier for ID field in database How to generate a simple cartesian plane system? I need to make a cartesian plane for plotting the straight line joining the points (-3,1) and (6,-2). This is a very simple cartesian plane plotting. When I looked at the manual for tikz the graphics for cartesian planes are for more advance plotting, and what I need is very simple.  Something like this: MySQL Prepared statements with a variable size variable list How would you write a prepared MySQL statement in PHP that takes a differing number of arguments each time? An example such query is:  SELECT `age`, `name` FROM `people` WHERE id IN (12, 45, 65, 33)   The IN clause will have a different number of ids each time it is run.  I have two possible solutions in my mind but want to see if there is a better way.  Possible Solution 1 Make the statement accept 100 variables and fill the rest with dummy values guaranteed not to be in the table; make multiple calls for more than 100 values.  Possible Solution 2 Don't use a prepared statement; build and run the query checking stringently for possible injection attacks. Packages: graphics vs graphicx Different websites suggest using one of those two packages.  \usepackage{graphicx} \usepackage{graphics}   What are differences between them? Which is better? How to login to gamecenter at PewDiePie's Tuber Simulator? How do I login to the Gamecenter on PewDiePie's Tuber Simulator, if you have not done it when they asked? After I add a user using adduser, I can't see it via System > Administration > Users and Groups unless I log out and then log in again. Is that normal?  Also, can I set a newly added user as a sudoer or do I have to change that only after adding it? How can I do that via the shell?  Finally, can I delete the original user that was created upon initial installation of Ubuntu, or is this user somehow 'special'? Add spanish spell check android studio I usually disconnect my cellphone from the charger some time after it's fully charged because I'm afraid the battery could lose capacity over time if I don't. However, I believe modern electronics should be able to handle this kind of scenario and automatically stop charging the battery once it's full. Does this apply to modern Android phones? Or do I need to continue disconnecting it all the time? Configuring, compiling and installing a custom Linux kernel Dealing with "java.lang.OutOfMemoryError: PermGen space" error Rkhunter warnings help I installed Ubuntu 14.04 a few days ago. I've made a scan with a RkHunter and got a few warnings that I don't really know what to do with. I read about false positives a little bit but I didn't find the answer for myself really. I got those errors:  Checking /dev for suspicious file types         [ Warning ] [19:44:16] Warning: Suspicious file types found in /dev: [19:44:16]          /dev/.udev/rules.d/root.rules: ASCII text [19:44:16]   Checking for hidden files and directories       [ Warning ] [19:44:16] Warning: Hidden directory found: /etc/.java: directory [19:44:16] Warning: Hidden directory found: /dev/.udev: directory [19:44:16] Warning: Hidden file found: /dev/.initramfs: symbolic link to `/run/initramfs' Checking for group file changes                 [ Warning ] [19:44:16] Warning: Group 'winbindd_priv' has been added to the group file.   Should I be worried ? How do deactivate plymouth boot screen? Lately, booting Ubuntu on my desktop has become seriously slow. We're talking two minutes. It used to take 10-20 seconds. Because of plymouth, I can't see what's going on. I would like to deactivate it, but not really uninstall it. What's the quickest way to do that? I'm using Precise, but I suspect a solution for 11.10 would work just as well.