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mongodb, replicates and error: { “$err” : “not master and slaveOk=false”, “code” : 13435 }
I tried mongo replica sets for the first time.
7 Answers
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Remove an element from a Bash array
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The following works as you would like in bash and zsh:
$ array=(pluto pippo)
$ delete=pluto
$ echo ${array[@]/$delete}
pippo
$ array=( "${array[@]/$delete}" ) #Quotes when working with strings
If need to delete more than one element:
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What is referential transparency?
...nts and arguments based on the methods of logic and mathematics. In other words, it is the closest subject outside computer science to what we call programming language semantics. The philosopher Willard Quine was responsible for initiating the concept of referential transparency, but it was also i...
Confused by python file mode “w+”
...t you write after this point
f.write('somedata\n')
f.seek(0) # Important: return to the top of the file before reading, otherwise you'll just read an empty string
data = f.read() # Returns 'somedata\n'
Note the f.seek(0) -- if you forget this, the f.read() call will try to read from t...
PHP - Get bool to echo false when false
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echo $bool_val ? 'true' : 'false';
Or if you only want output when it's false:
echo !$bool_val ? 'false' : '';
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Modulo operator with negative values [duplicate]
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From ISO14882:2011(e) 5.6-4:
The binary / operator yields the quotient, and the binary % operator
yields the remainder from the division of the first expression by the
second. If the second operand of / or % is zero the behavior is
undefined. For integral operands th...
What's a concise way to check that environment variables are set in a Unix shell script?
...cripts where I need to check that certain environment variables are set before I start doing stuff, so I do this sort of thing:
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What does cmd /C mean? [closed]
... but not cmd /c . I was trying to invoke a java program from the current for which I use Runtime.getRuntime().exec("cmd /C java helloworld"); There arises my doubt.
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What's the regular expression that matches a square bracket?
...all possibilities, but haven't found the right one. What is a valid regex for this?
8 Answers
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python ? (conditional/ternary) operator for assignments [duplicate]
C and many other languages have a conditional (aka ternary) operator. This allows you to make very terse choices between two values based on the truth of a condition, which makes expressions, including assignments, very concise.
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