Difference between 'if [ "x$foo" = "x1" ]' vs 'if [ "$foo" = "1" ]' in bash?
Why do shell script comparisons often use x$VAR = xyes?
Charm Person has verbal and somatic components.  Is there anything in the rules as written that defines how obvious those verbal and somatic components are?  Would it be obvious the caster was casting a spell from 5 feet away?  From across a crowded room?  I'm specifically interested in an answer based on the rules as written, although interpretation and individual opinion are not unwelcome. Prove that inequality is true for $x>0$: $(e^x-1)\ln(1+x) > x^2$ Shell Script for logging into a ssh server Why does the definition of limits of a function have strict inequality? Definition (As written in Michael Spivak's Calculus)     The function $f$ approaches a limit $l$ near $a$ means: for every $\epsilon &gt;0$ there is some $\delta &gt; 0$ such that, for all $x$, if $0&lt;|x-a|&lt;\delta$, then $|f(x)-l|&lt;\epsilon$.   my question is: why can't it be: $$0&lt;|x-a|\leq \delta,|f(x)-l|\leq \epsilon$$ After looking at limits of functions for a long time just to grasp it's meaning and using the definition quite a lot solving homework I realized I keep writing the same inequality without really understanding why.  The only explanation given in Spivak's book for this part of the definition goes over it without explaining the inequality. I tried looking for an explanation myself but wasn't really able to find anything wrong with it. Is it also possible to write the definition like that or is there a problem with that?   (first non-homework related question :p) How to order files by last modified time in ruby? Don't know what could it be but my daughter keeps on crying every night. She's sleeping and suddenly she starts crying. Hungry ? (She drinks her last bottle of milk around 8pm.) Maybe teething? (every night, don't think so) Miss being in mommy's and daddy's bed? (she cries even if she's in our bed) I'm out of ideas, and we are kind of exhausted! Any ideas what might be the reason for her to cry every night? I tried to add a new repository to software sources, but "add source" button is unavailable. I can't click on it.  I also tried to add a new software source from the terminal, but it didn't work.  sudo‬‬ ‫‪add-apt-repository‬‬ ‫‪ppa:n-muench/burg‬‬   s‫‪udo‬‬: command not found     I also tried these commands:  ‫‪sudo‬‬ ‫‪add-apt-repository‬‬ ‫‪deb‬‬ ‫‪http://ppa.launchpad.net/n-muench/burg/ubuntu‬‬ natty‬‬ ‫‪main‬‬   sudo‬‬: command not found Is there any software to sync files-folders and software between two PCs? For example if I install program 'A' to my desktop I want to be installed to my laptop as well if I have synchronized these two. I want the same with my files and folders. If I change something to my desktop I want the changes to effect my laptop too(I exclude Ubuntu One as a solution).  Thanks for your time and patience! "Open in browser" does nothing when Android app is set as default How do I call one constructor from another in Java? Is it possible to call a constructor from another (within the same class, not from a subclass)? If yes how? And what could be the best way to call another constructor (if there are several ways to do it)? CSS Transform Skew Is there a way to make PythonTEX compile as of today in Overleaf V2 ?  \documentclass[]{article} \usepackage[utf8]{inputenc} \usepackage{pythontex}  \begin{document} \begin{pyverbatim} def calc_ellipticity(theta, delta):     theta = np.deg2rad(theta)     psi = np.arcsin(np.sin(2*theta) * np.sin(delta))/2     return np.tan(psi) \end{pyverbatim} \end{document}   Compiling gives : ? PythonTEX ? What do the colors mean in htop? Is there any matrix $2\times 2$ such that $A\neq I$ but $ A^3=I$? Is there any $2 \times 2$ matrix $A \neq I$ such that $A^3=I$?  In my opinion: no. Thank you very much. When watching US television news or reading US news articles there is this affectation where instead of saying:     "Spotify music-streaming service to launch in U.S. on Thursday" ()   or      "Leading credit rating agency Moody's said on Wednesday that the U.S. government's impeccable credit..." ()   The on preposition is missed out.  Is this just a peculiar US journalistic "news speak" shortcut or do American non-journalist writers write this way too? php--glob for searching directories and .jpg only Good-morning Math Exchange (and good evening to some!)  I have a very basic question that is confusing me.   At school I was told that $\sqrt {a^2} = \pm a$  However, does this mean that $\sqrt {a^2} = +2$ *and*$-2$ or does it mean: $\sqrt {a^2} = +2$ *OR*$-2$  Is it wrong to say 'and'? What are the implications of choosing 'and'/'or'  Any help would be greatly appreciated. Thanks in advance and enjoy the rest of your day :) Why doesn't my systemd user unit start at boot? Just a few questions about Hyper-V virtual machines and clustering I have been using Microsoft’s Hyper-V technology for a little while now, but I am just now dipping my toe into clustering.  In particular, I am trying to implement a fault-tolerant SQL DB. This involves setting up two VMs, clustering them via Failover Cluster, and then installing SQL Server in some fashion. I have two physical machines - one high-end and rather beefy “heavy lifter” to contain the majority of the VMs, and another “backup” (a repurposed desktop) to hold the essential “secondary” (or failover) AD-DC, SQL and FS VMs.  The main reason why I find the failover cluster at the VM level so attractive is that it presents a single IP and DNS entry to the network as a whole - if one machine (physical or virtual) goes down, you might loose some ping and the connections get reset, but the network applications (Microsoft RMS connection to backend SQL) can still connect to a viable DB without having to mess around with the settings at all.  My first question is in terms of SQL Server itself. If I have a cluster between two VMs, does it make more sense to install the SQL Server in Failover Cluster configuration or should I simply install it in a stand-alone config and mirror the DBs? For example,  suggests just mirroring the DBs, but do I just mirror standalone DBs on standalone VMs, or can I get the network and failover benefits of clustered VMs while still utilizing (on each clustered VM) standalone DBs that have been mirrored between each other?  As well, I have come across a lot of documentation about SQL clustering, but most assume a number (#>2) of physical machines to hold not only the actual SQL VMs but also the Quorum and Witness stores. I will not be able to muster more than two physical machines. As such, I will have to be satisfied with a VM cluster that does not exceed two VMs (one for each physical machine).  Another issue involves MSDTC - the Distributed Transaction Coordinator. When attempting to install the SQL Failover Cluster (I never completed it for this reason) it threw a hissy fit because MSDTC had not been clustered. Search as I might, I have not yet found a way to do so under Windows Server 2012 R2. I have found , but these instructions don’t align with 2012 R2 (at least, not in a way that allows me to successfully cluster MSDTC). Plus,  that I have found for SQL Server Failover Cluster installation suggest that a third “network device” - shared network storage (a SAN) - is required for the DB itself (and other functionality). I do not have this, and won’t be getting this. Most of my storage exists on the “heavy lifter” that was designed for all of the “primary” VMs. If that physical machine goes down, so does the storage. The secondary server does have enough resources for an AD-DC Server, an SQL server and a File Server, so it will handle the “secondary” failover versions of those VMs (clustered or not).  My final question involves file servers. If I cluster file servers between two VMs (one on my “heavy lifter” and another on my “backup”, how do I mirror the data between them? Clustering VMs only provides a single point of access on the network for a resource, it doesn’t exactly replicate data between the two - that is left to the services that serve up that data. I am unsure how I can ensure that file server data between two clustered file server VMs can be properly mirrored. Remember, I only have two devices to be used here - my primary machine and a backup secondary. There is no chance of me obtaining a SAN or any other type of network attached storage. What exists on the machines must act as the storage.  Thanks in advance for any suggestions. How to get product recommendations Possible Duplicate:          I have a question of the form "what companies provide service X?"  I checked meta, and apparently such questions are highly discouraged on all Stack Exchange sites. Which is fine, but it obviously raises the meta-question: Where can I ask my question?  (In particular, I know that there are people hanging out on Stack Overflow who have probably needed the same service, so if an answer exists, they possess it...)  Edit: I should perhaps point out that the service I'm looking for is rather specific and slightly obscure. Otherwise, yeah, this would be a 10-second exercise with Google.