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What does the line “#!/bin/sh” mean in a UNIX shell script?
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It's called a shebang, and tells the parent shell which interpreter should be used to execute the script.
e.g.
#!/usr/bin/perl <--perl script'
#!/usr/bin/php <-- php script
#!/bin/false <--- do-nothing script, because ...
What's the meaning of Base SDK, iOS deployment target, Target, and Project in xcode
...ect can have multiple targets and you might not want the same settings for all targets. The project-level settings override the default settings and the target-level settings override the project-level settings.
For example I have projects with both OSX and iOS targets and some are ARC and some ar...
PDO's query vs execute
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query runs a standard SQL statement and requires you to properly escape all data to avoid SQL Injections and other issues.
execute runs a prepared statement which allows you to bind parameters to avoid the need to escape or quote the parameters. execute will also perform better if you are repeat...
Why is document.body null in my javascript?
...body hasn't been defined at this point yet. In general, you want to create all elements before you execute javascript that uses these elements. In this case you have some javascript in the head section that uses body. Not cool.
You want to wrap this code in a window.onload handler or place it after...
How to get an array of specific “key” in multidimensional array without looping
...s = array_map(function ($ar) {return $ar['id'];}, $users);
Before(Technically php 4.0.6+), you must create an anonymous function with create_function instead:
$ids = array_map(create_function('$ar', 'return $ar["id"];'), $users);
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What is the difference between ArrayList.clear() and ArrayList.removeAll()?
...st is defined as ArrayList<String> arraylist , is arraylist.removeAll(arraylist) equivalent to arraylist.clear() ?
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How do I break out of nested loops in Java?
...ption (sorry). But I'd still be unhappy about this if it wasn't obvious (small loops, warning comment if the label/break still aren't visible enough).
– Steve314
Dec 7 '11 at 0:40
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Why does document.querySelectorAll return a StaticNodeList rather than a real Array?
It bugs me that I can't just do document.querySelectorAll(...).map(...) even in Firefox 3.6, and I still can't find an answer, so I thought I'd cross-post on SO the question from this blog:
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Get escaped URL parameter
... you may want "decodeURIComponent()" instead of "decodeURI()", especially if you are passing interesting data like return URLs in as a URL parameter
– perfectionist
Feb 27 '12 at 13:14
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SQL join: selecting the last records in a one-to-many relationship
... purchases. Each purchase belongs to one customer. I want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes?
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