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How to tell if a string is not defined in a Bash shell script

...o use a default value, ${foo:=default} to assign the default value, ${foo:?error message} to display an error message if foo is unset, etc. – Jouni K. Seppänen Oct 23 '08 at 4:54 ...
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Retrieving a random item from ArrayList [duplicate]

...has never been declared as a variable, so it makes sense that it causes an error. But more importantly, you have code after a return statement and this will cause an unreachable code error. share | ...
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Vim multiline editing like in sublimetext?

I started to use gvim, and I can't quite understand how the multiline edit works in gvim. 7 Answers ...
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What is the significance of initializing direction arrays below with given values when developing ch

I am new to competitive programming, and I noticed frequently, many of the great coders have these four lines in their code (particularly in those involving arrays): ...
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How to detect the physical connected state of a network cable/connector?

... The errors about directories from grep can be ignored with: grep -s "" eth0/* – mrtumnus Jul 25 '18 at 0:37 ...
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Is it possible to dynamically compile and execute C# code fragments?

... select i; } }"); results.Errors.Cast<CompilerError>().ToList().ForEach(error => Console.WriteLine(error.ErrorText)); } } The class of primary importance here is the CSharpCodeProvider which utilises the compiler to compile code on the ...
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How do I include a JavaScript file in another JavaScript file?

...jsFilePath; document.body.appendChild(js); var s = new MySuperObject(); Error : MySuperObject is undefined Then you reload the page hitting F5. And it works! Confusing... So what to do about it ? Well, you can use the hack the author suggests in the link I gave you. In summary, for people in ...
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How can I combine hashes in Perl?

What is the best way to combine both hashes into %hash1? I always know that %hash2 and %hash1 always have unique keys. I would also prefer a single line of code if possible. ...
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What is the purpose of willSet and didSet in Swift?

Swift has a property declaration syntax very similar to C#'s: 11 Answers 11 ...
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How can I list ALL DNS records?

Is there any way I can list ALL DNS records for a domain? 8 Answers 8 ...