Can Ubuntu be installed on any hardware?
How do I install Ubuntu?
Is there an alternative to string.Replace that is case-insensitive? I need to search a string and replace all occurrences of %FirstName% and %PolicyAmount% with a value pulled from a database. The problem is the capitalization of FirstName varies. That prevents me from using the String.Replace() method. I've seen web pages on the subject that suggest  Regex.Replace(strInput, strToken, strReplaceWith, RegexOptions.IgnoreCase);   However for some reason when I try and replace %PolicyAmount% with $0, the replacement never takes place. I assume that it has something to do with the dollar sign being a reserved character in regex.   Is there another method I can use that doesn't involve sanitizing the input to deal with regex special characters? I am trying to help my daughter on her math homework and I am having some trouble on some equation solving steps. My current major concern relies on understanding why $\sqrt{8}/2$ equal to $\sqrt{2}$.  Thanks in advance Let $A,B,C$ be sets, and $B \cap C=\emptyset$. Show $|A^{B \cup C}|=|A^B \times A^C|$ Let $A,B,C$ be sets, and $B \cap C=\emptyset$. Show $|A^{B \cup C}|=|A^B \times A^C|$ by defining a bijection $f:A^{B \cup C} \rightarrow A^B \times A^C$.  Any hints on this one?  Thank you! In unix server grep -r option is not working. OS is HP-UX.  If grep -r is not working any alternative way to do recursive search without -r option? I have a shapefile and I want to change the order of the features. Is that possible? I want to sort the features in the shapefile because I'm embedding this shapefile in a mobile app. The app will display a list of features, and although I could do the sorting at load time, I'd prefer to have them sorted. Why does Perl's sprintf not round floating point numbers correctly? Natural deduction, Proof $\vdash$ $P\Rightarrow(Q\Rightarrow P)$ So I have a question regarding natural deduction, are we allowed to "copy" our previous assumption inside a new assumption. I will use an example to illustrate.  $\vdash$ $P\Rightarrow(Q\Rightarrow P)$  So here are my steps.  1.) $P$             Assumption  2.)$Q$             Assumption  3.)$P$             Copy (1)  4.)$Q \Rightarrow P$   Implication Introduction  5.)$P \Rightarrow (Q \Rightarrow P)$ Implication Introduction  Is my proof correct, or is there something missing. setTimeout and "this" in JavaScript I have a method that uses the  function and makes a call to another method. On initial load method 2 works fine. However, after the timeout, I get an error that says method2 is undefined. What am I doing wrong here?  ex:  test.prototype.method = function() {     //method2 returns image based on the id passed     this.method2('useSomeElement').src = "http://www.some.url";     timeDelay = window.setTimeout(this.method, 5000); };  test.prototype.method2 = function(name) {     for (var i = 0; i &lt; document.images.length; i++) {         if (document.images[i].id.indexOf(name) &gt; 1) {             return document.images[i];         }     } }; Why would I need a firewall if my server is well configured? What is a NullPointerException, and how do I fix it? First, if you have a better suggestion for title I'm really opened to suggestions, but it is the best I came up with.  If I touch an electric line and the earth, I will get electrocuted.  However, if I touch the positive of a car battery, people told me the same thing won't happen...why is it?  It seems I need to touch the battery positive and the battery ground. How is Cycles different from Blender Internal? Port forwarding with UFW I realize UFW is mainly just for enabling/disabling access on particular ports, but I'm trying to forward one port to another. I want any connection to port 1724 to be forwarded to 1723.   The file /etc/default/ufw already has DEFAULT_FORWARD_POLICY="ACCEPT". And I believe I need to uncomment net/ipv4/ip_forward=1 in /etc/ufw/sysctl.conf. Finally I need to edit /etc/ufw/before.rules to add an iptables rule.   And here is where I get lost because I can't find any documentation for this file. Where do I add the rule? And how exactly?  In particular:   On exactly which line do I add the rule? Do I put anything before or after it? Can anyone show me how to find invertible elements in $\mathbb{Z}/m\mathbb{Z}$, $m$ is say $28$?  Also I'm not very clear about what it mean by 'invertible element in $\mathbb{Z}/m\mathbb{Z}$' Expected log value of noncentral exponential distribution I think it would be good to have a way for the user to view the target URL of a link before following it. I'm pretty sure that I'm not the only one who dislikes blind-clicking -tapping links.   When I use SE in the mobile browser, I routinely long-press links to find out where they go before following them. I wish I could do the same thing in the app, with the same or a similar method.  (It's important that this won't conflict with text selection, since you can't long-press on links to select them now anyway.) Degrees of freedom for standard deviation of sample would someone please explain why the degrees of freedom for a random sample is n-1 instead of n ?   I'm looking for an explanation that is intuitive and easily understood by a high school student. How to add current date to cell if the rest of the cells (or some cells) in that row are edited, but only the first time? I have a column A4:A (heading = Date), and other columns after it B4:O.  I want column A to fill in today's date automatically when I fill in any other columns (some of these B4:O maybe empty, but most will be filled) in that row. But I only want that to happen the first time I edit any other columns within that row.  What I've tried:  A7: =IF(B7 &gt; 0,TODAY(),) What's the difference between the simple past tense and the present perfect? The simple past tense indicates that an activity or situation began   and ended at a particular time in the past.      The present perfect expresses the idea that something happened (or   never happened) before now, at an unspecified time in the past.The   exact time it happened is not important. It also expresses the   repetition of an activity before now. The exact time of each   repetition is not important.   Even though I understand the explanation above, I can't figure out: If the present perfect states the idea that something happened in the past, why not use the simple past?  For example, would you please explain the following sentence to tell the difference between these two tenses?         The plane crashed there.    The plane has crashed there.      What is the biggest difference between them? How to parse a string into a nullable int