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Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]
...s a more complete version that shows more differences between [ (aka test) and [[.
The following table shows that whether a variable is quoted or not, whether you use single or double brackets and whether the variable contains only a space are the things that affect whether using a test with or wit...
Comprehensive beginner's virtualenv tutorial? [closed]
I've been hearing the buzz about virtualenv lately, and I'm interested. But all I've heard is a smattering of praise, and don't have a clear understanding of what it is or how to use it.
...
How can I close a Twitter Bootstrap popover with a click from anywhere (else) on the page?
...y time, you can use a set of flags to mark when there's a popover visible, and only then hide them.
If you set the event listener on the document body, it will trigger when you click the element marked with 'popup-marker'. So you'll have to call stopPropagation() on the event object. And apply the ...
What is the difference between Ruby 1.8 and Ruby 1.9
...m not clear on the differences between the "current" version of Ruby (1.8) and the "new" version (1.9). Is there an "easy" or a "simple" explanation of the differences and why it is so different?
...
Performance of foreach, array_map with lambda and array_map with static function
...2 compare with mcfedr's answer below for additional results without XDebug and a more recent PHP version.
function lap($func) {
$t0 = microtime(1);
$numbers = range(0, 1000000);
$ret = $func($numbers);
$t1 = microtime(1);
return array($t1 - $t0, $ret);
}
function useForeach($numbers) {...
How do the post increment (i++) and pre increment (++i) operators work in Java?
...=>
i=5 + 7 + 8; (a=8)
The main point is that ++a increments the value and immediately returns it.
a++ also increments the value (in the background) but returns unchanged value of the variable - what looks like it is executed later.
...
What is the difference in maven between dependency and plugin tags in pom xml?
I'm new to the maven tool, I have made a project with Spring and Hibernate and they are configured in pom.xml as plugins, but JUnit is tagged under dependency. My question is what is the logic behind one as a plugin and one as dependency ?
...
What is the canonical way to check for errors using the CUDA runtime API?
Looking through the answers and comments on CUDA questions, and in the CUDA tag wiki , I see it is often suggested that the return status of every API call should checked for errors. The API documentation contains functions like cudaGetLastError , cudaPeekAtLastError , and cudaGetErrorString , b...
What is the purpose and use of **kwargs?
...x when calling functions by constructing a dictionary of keyword arguments and passing it to your function:
>>> kwargs = {'first_name': 'Bobby', 'last_name': 'Smith'}
>>> print_keyword_args(**kwargs)
first_name = Bobby
last_name = Smith
The Python Tutorial contains a good explan...
What is the best way to ensure only one instance of a Bash script is running? [duplicate]
... 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.lock
[Terminal #2] lockfile: Sorry, giving up on "/tmp/the.lock"
[Terminal #1] $ rm -f /tmp/the....