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Best way to test if a row exists in a MySQL table
...RE ...)
and per the documentation, you can SELECT anything.
Traditionally, an EXISTS subquery starts with SELECT *, but it could
begin with SELECT 5 or SELECT column1 or anything at all. MySQL
ignores the SELECT list in such a subquery, so it makes no difference.
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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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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 to force cp to overwrite without confirmation
.... However, if you use -nf it adds the ability to clear the -i. So:
cp -f /foo/* /bar <-- Prompt
cp -nf /foo/* /bar <-- No Prompt
Pretty neat huh? /necropost
Why is it slower to iterate over a small string than a small list?
...nd with timeit and noticed that doing a simple list comprehension over a small string took longer than doing the same operation on a list of small single character strings. Any explanation? It's almost 1.35 times as much time.
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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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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 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...
AngularJS $resource RESTful example
...esource('/api/1/todo/:id');
//create a todo
var todo1 = new Todo();
todo1.foo = 'bar';
todo1.something = 123;
todo1.$save();
//get and update a todo
var todo2 = Todo.get({id: 123});
todo2.foo += '!';
todo2.$save();
//which is basically the same as...
Todo.get({id: 123}, function(todo) {
todo.f...
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...