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Using unset vs. setting a variable to empty
...t; unset var
/home/user1> echo $var
-bash: var: unbound variable
So really, it depends on how you are going to test the variable.
I will add that my preferred way of testing if it is set is:
[[ -n $var ]] # True if the length of $var is non-zero
or
[[ -z $var ]] # True if zero length
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How do I find files that do not contain a given string pattern?
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Take a look at ack. It does the .svn exclusion for you automatically, gives you Perl regular expressions, and is a simple download of a single Perl program.
The equivalent of what you're looking for should be, in ack:
ack -L foo
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Extracting extension from filename in Python
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@klingt.net Well, in that case, .asd is really the extension!! If you think about it, foo.tar.gz is a gzip-compressed file (.gz) which happens to be a tar file (.tar). But it is a gzip file in first place. I wouldn't expect it to return the dual extension at all.
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Greedy vs. Reluctant vs. Possessive Quantifiers
...leaving the "foo" at the end of the string unmatched). Now, the matcher finally matches the f in the regex, and the o and the next o are matched too. Success!
A reluctant or "non-greedy" quantifier first matches as little as possible. So the .* matches nothing at first, leaving the entire string un...
Running V8 Javascript Engine Standalone
...> ./v8-shell
V8 version 2.0.2
> var x = 10;
> x
10
> function foo(x) { return x * x; }
> foo
function foo(x) { return x * x; }
> quit()
Executing Javascript from the command line:
$> ./v8-shell -e 'print("10*10 = " + 10*10)'
10*10 = 100
Many more features are documented i...
Remove blank attributes from an Object in Javascript
How do I remove all attributes which are undefined or null in a JavaScript object?
37 Answers
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Get array of object's keys
...keys are unordered).
This is an ES5 feature. This means it works in all modern browsers but will not work in legacy browsers.
The ES5-shim has a implementation of Object.keys you can steal
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Remove by _id in MongoDB console
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I've just bumped into this myself and this variation worked for me:
db.foo.remove({**_id**: new ObjectId("4f872685a64eed5a980ca536")})
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foll...
How do I pass the this context to a function?
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Javascripts .call() and .apply() methods allow you to set the context for a function.
var myfunc = function(){
alert(this.name);
};
var obj_a = {
name: "FOO"
};
var obj_b = {
name: "BAR!!"
};
Now you can call:
myfunc.ca...
Getting raw SQL query string from PDO prepared statements
Is there a way to get the raw SQL string executed when calling PDOStatement::execute() on a prepared statement? For debugging purposes this would be extremely useful.
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