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What is the best way to ensure only one instance of a Bash script is running? [duplicate]
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If the script is the same across all users, you can use a lockfile approach. If you acquire the lock, proceed else show a message and exit.
As an example:
[Terminal #1] $ lockfile -r 0 /tmp/the.lock
[Terminal #1] $
[Terminal #2] $ lockfile -r 0 /tmp/the....
Does Python support multithreading? Can it speed up execution time?
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The GIL does not prevent threading. All the GIL does is make sure only one thread is executing Python code at a time; control still switches between threads.
What the GIL prevents then, is making use of more than one CPU core or separate CPUs to run threads in...
How should I copy Strings in Java?
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@GriffeyDog: I am reading the question less literally. What I am saying is that it is safe to give out references to a string object without fear that someone might modify the string.
– NPE
May 15 '12 at 20:12
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Simulating tremor (from e.g. Parkinson's Disease) with the mouse on a webpage?
...or accessibility in the internet. For a presentation, we want to offer a small workshop that simulates different disabilities/impairments to people. This is done via a website created especially for this presentation.
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Using jQuery To Get Size of Viewport
....375.70, Opera 10.53, and Safari 5.0 (7533.16). This works consistently on all of these. I also tested FF3.6.3 on Ubuntu and it works there too. I think I'm using jQuery 1.3 with WordPress 2.9.2, which is where I needed this to work.
– Volomike
Jun 16 '10 at 3:...
Android accelerometer accuracy (Inertial navigation)
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It's quite different to the old manually-take-some-pictures-then-stitch-them-later job. It does track its position in real time somehow. It's a little difficult to explain without demonstrating it. You don't have to take pictures manually - the phone decides...
Haskell composition (.) vs F#'s pipe forward operator (|>)
...s pipelining, so that a known type appears on the left (see here).
(Personally, I find points-free style unreadable, but I suppose every new/different thing seems unreadable until you become accustomed to it.)
I think both are potentially viable in either language, and history/culture/accident may...
NSUserDefaults removeObjectForKey vs. setObject:nil
... *keys = [[[NSUserDefaults standardUserDefaults] dictionaryRepresentation] allKeys] copy];
for(NSString *key in keys) {
NSLog(@"Key Name: %@", key);
}
[keys release];
or simply dump the key/value dictionary of NSUserDefaults standardUserDefaults
NSLog(@"All contents of NSUserDefaults: %...
How to get the class of the clicked element?
...on() {
var myClass = $(this).attr("class");
alert(myClass);
});
Equally, you don't have to wrap the object in jQuery:
$("li").click(function() {
var myClass = this.className;
alert(myClass);
});
And in newer browsers you can get the full list of class names:
$("li").click(function(...
Hide/Show Column in an HTML Table
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I would like to do this without attaching a class to every td
Personally, I would go with the the class-on-each-td/th/col approach. Then you can switch columns on and off using a single write to className on the container, assuming style rules like:
table.hide1 .col1 { display: none; }
table...