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What's the difference between Perl's backticks, system, and exec?
...It never returns true, because if the command is found it never returns at all.
There is also no point in returning STDOUT, STDERR or exit status of the command.
You can find documentation about it in perlfunc,
because it is a function.
system
executes a command and your Perl script is con...
How can I let a table's body scroll but keep its head fixed in place?
...in a set size. I need the headers at the top of the table to stay there at all times but I also need the body of the table to scroll no matter how many rows are added to the table. Think a mini version of excel. This seems like a simple task but almost every solution I have found on the web has some...
Could not load file or assembly 'System.Net.Http.Formatting' or one of its dependencies. The system
I have a small MVC app that I use for practice reasons, but now I am encountering an error every time I try to debug:
18 An...
What is a serialVersionUID and why should I use it?
...ization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. If the receiv...
Why is there no logical xor in JavaScript?
...r. Mainly because it's not useful. Bitwise XOR is extremely useful, but in all my years of programming I have never needed a logical XOR.
If you have two boolean variables you can mimic XOR with:
if (a != b)
With two arbitrary variables you could use ! to coerce them to boolean values and then u...
django - why is the request.POST object immutable?
...
It's a bit of a mystery, isn't it? Several superficially plausible theories turn out to be wrong on investigation:
So that the POST object doesn't have to implement mutation methods? No: the POST object belongs to the django.http.QueryDict class, which implements a full set ...
Can I run multiple versions of Google Chrome on the same machine? (Mac or Windows)
...
In the comments, I mentioned a step-by-step method to easily install multiple Chrome versions, side-by-side. This answer quotes my original answer, and includes a script which does the job for you.
Quoted from: section 7 of Cross-browser testing: All major browsers on ONE machine:
...
change type of input field with jQuery
... or part of their security model, but jQuery isn't specific):
// We can't allow the type property to be changed (since it causes problems in IE)
if ( name == "type" && jQuery.nodeName( elem, "input" ) && elem.parentNode )
throw "type property can't be changed";
...
hadoop No FileSystem for scheme: file
...tem, hadoop-hdfs for DistributedFileSystem) each contain a different file called org.apache.hadoop.fs.FileSystem in their META-INFO/services directory. This file lists the canonical classnames of the filesystem implementations they want to declare (This is called a Service Provider Interface impleme...
What are the differences between the different saving methods in Hibernate?
...g of the methods. Mainly these are based on the API though as I don't use all of these in practice.
saveOrUpdate
Calls either save or update depending on some checks. E.g. if no identifier exists, save is called. Otherwise update is called.
save
Persists an entity. Will assign an identifier if...