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Echo newline in Bash prints literal \n
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Are you sure you are in bash? Works for me, all four ways:
echo -e "Hello\nworld"
echo -e 'Hello\nworld'
echo Hello$'\n'world
echo Hello ; echo world
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Get top n records for each group of grouped results
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Here is one way to do this, using UNION ALL (See SQL Fiddle with Demo). This works with two groups, if you have more than two groups, then you would need to specify the group number and add queries for each group:
(
select *
from mytable
where `group` = 1
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How to define optional methods in Swift protocol?
...an take advantage of powerful generics system.
You can always be sure that all requirements are met when encountering types that conform to such protocol. It's always either concrete implementation or default one. This is how "interfaces" or "contracts" behave in other languages.
Disadvantages
F...
How do I get the collection of Model State Errors in ASP.NET MVC?
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@DaveH Yep, you should totally check for existence first
– Alex Lyman
Dec 4 '13 at 20:03
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How do I disable a jquery-ui draggable?
...docs for draggable() are here. Same goes for sortable() objects (if you're allowing drag-n-drop reordering.)
– nickb
Apr 7 '11 at 2:52
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Batch script: how to check for admin rights
...went searching for other commands that require elevated permissions. rationallyparanoid.com had a list of a few, so I ran each command on the two opposite extremes of current Windows OSs (XP and 8) in the hopes of finding a command that would be denied access on both OSs when run with standard permi...
Is there any way to put malicious code into a regular expression?
...o solve. These may only show up on particular input data, but one can generally create one wherein this doesn’t matter.
Which ones these are will depend somewhat on how smart the regex compiler you’re using happens to be, because some of these can be detected during compilation time. Regex com...
MongoDB: How to update multiple documents with a single command?
...: 'field1', field2: 'field2'})
New in version 3.2
Params::
{}: select all records updated
Keyword argument multi not taken
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Python non-greedy regexes
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You seek the all-powerful *?
From the docs, Greedy versus Non-Greedy
the non-greedy qualifiers *?, +?, ??, or {m,n}? [...] match as little
text as possible.
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OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection
...e I was unable to find a relevant implementation I decided to accept the challenge.
I made some modifications to the squares demo present in OpenCV and the resulting C++ code below is able to detect a sheet of paper in the image:
void find_squares(Mat& image, vector<vector<Point> >...