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What does `kill -0 $pid` in a shell script do?
... 0 to a given PID just checks if any process with the given PID is running and you have the permission to send a signal to it.
For more information see the following manpages:
kill(1)
$ man 1 kill
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If sig is 0, then no signal is sent, but error checking is still performed.
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kill(2)
$ man...
When should I use double or single quotes in JavaScript?
...r use of single vs. double in different libraries is programmer preference and/or API consistency. Other than being consistent, use whichever best suits the string.
Using the other type of quote as a literal:
alert('Say "Hello"');
alert("Say 'Hello'");
This can get complicated:
alert("It's \"game\"...
What's the difference between using CGFloat and float?
...mething "heavier" than float, right? At which points should I use CGFloat, and what makes really the difference?
5 Answers
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How do I check if a type is a subtype OR the type of an object?
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Here's the options:
Use Type.IsSubclassOf
Use Type.IsAssignableFrom
is and as
Type.IsSubclassOf
As you've already found out, this will not work if the two types are the same, here's a sample LINQPad program that demonstrates:
void Main()
{
typeof(Derived).IsSubclassOf(typeof(Base)).Dump(...
round() for float in C++
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there is also lround and llround for integral results
– sp2danny
Feb 23 '15 at 11:55
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How to check date of last change in stored procedure or function in SQL server
...crosoft.com/en-us/library/ms190324%28v=sql.105%29.aspx "In SQL Server 2005 and later versions, the visibility of the metadata in catalog views is limited to securables that a user either owns or on which the user has been granted some permission. For more information, see Metadata Visibility Configu...
Zoom in on a point (using scale and translate)
...the change in the zoom. The zoom point is simply the point in the old zoom and the new zoom that you want to remain the same. Which is to say the viewport pre-zoomed and the viewport post-zoomed have the same zoompoint relative to the viewport. Given that we're scaling relative to the origin. You ca...
How do I concatenate or merge arrays in Swift?
... Khunshan: AnyObject indicates an object, which as I understand means something that is instantiated from a class type. CGFloat is not an object, it is a scalar value. As I understand it, arrays can contain scalars, unless it is defined as containing AnyObject or are further refined. ...
Detecting that the browser has no mouse and is touch-only
...ifferent interface for touch (your finger hides the screen when you click) and mouse (relies heavily on hover preview).
How can I detect that my user has no mouse to present him the right interface? I plan to leave a switch for people with both mouse and touch (like some notebooks).
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filter for complete cases in data.frame using dplyr (case-wise deletion)
...works, of course. But that is a) verbose when there are a lot of variables and b) impossible when the variable names are not known (e.g. in a function that processes any data.frame).
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