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What is the use case of noop [:] in bash?
...ver'
done
It's traditional to use : when the shell syntax requires a command but you have nothing to do.
while keep_waiting; do
: # busy-wait
done
The : builtin dates all the way back to the Thompson shell, it was present in Unix v6. : was a label indicator for the Thompson shell's goto state...
Ruby on Rails - Import Data from a CSV file
...ase table. I do not want to save the CSV file, just take the data from it and put it into the existing table. I am using Ruby 1.9.2 and Rails 3.
...
string.charAt(x) or string[x]?
...
Bracket notation now works on all major browsers, except for IE7 and below.
// Bracket Notation
"Test String1"[6]
// charAt Implementation
"Test String1".charAt(6)
It used to be a bad idea to use brackets, for these reasons (Source):
This notation does not work in IE7.
The first...
How can a Java variable be different from itself?
...same with Double.NaN.
From JLS §15.21.1. Numerical Equality Operators == and !=:
Floating-point equality testing is performed in accordance with the rules of the IEEE 754 standard:
If either operand is NaN, then the result of == is false but the result of != is true.
Indeed, the test x!=x is tru...
What does O(log n) mean exactly?
I am learning about Big O Notation running times and amortized times. I understand the notion of O(n) linear time, meaning that the size of the input affects the growth of the algorithm proportionally...and the same goes for, for example, quadratic time O(n2) etc..even algorithms, such as permu...
Can I make git recognize a UTF-16 file as text?
I'm tracking a Virtual PC virtual machine file (*.vmc) in git, and after making a change git identified the file as binary and wouldn't diff it for me. I discovered that the file was encoded in UTF-16.
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How do I request a file but not save it with Wget? [closed]
...
Use q flag for quiet mode, and tell wget to output to stdout with O- (uppercase o) and redirect to /dev/null to discard the output:
wget -qO- $url &> /dev/null
> redirects application output (to a file). if > is preceded by ampersand, sh...
How do I focus on one spec in jasmine.js?
... can run just the whole spec by this url http://localhost:8888?spec=MySpec and a the first test with http://localhost:8888?spec=MySpec+function+1
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Script parameters in Bash
...arguments that you provide to a bashscript will appear in the variables $1 and $2 and $3 where the number refers to the argument. $0 is the command itself.
The arguments are seperated by spaces, so if you would provide the -from and -to in the command, they will end up in these variables too, so fo...
Not equal != operator on NULL
...
<> is Standard SQL-92; != is its equivalent. Both evaluate for values, which NULL is not -- NULL is a placeholder to say there is the absence of a value.
Which is why you can only use IS NULL/IS NOT NULL as predicates for such situ...