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How to find whether or not a variable is empty in Bash
How can I check if a variable is empty in Bash?
10 Answers
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Determine if an element has a CSS class with jQuery
I'm working with jQuery and looking to see if there is an easy way to determine if the element has a specific CSS class associated with it.
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Check if $_POST exists
I'm trying to check whether a $_POST exists and if it does, print it inside another string, if not, don't print at all.
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Regular expression to match any character being repeated more than 10 times
...he same character being repeated more than 10 or so times. So for example, if I have a document littered with horizontal lines:
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MySQL CONCAT returns NULL if any field contain NULL
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You can use if select CONCAT(if(affiliate_name is null ,'',affiliate_name),'- ',if(model is null ,'',affiliate_name)) as model from devices
– Dinesh Rabara
Sep 24 '15 at 13:41
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Check for installed packages before running install.packages() [duplicate]
I have an R script that is shared with several users on different computers. One of its lines contains the install.packages("xtable") command.
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How to know if user is logged in with passport.js?
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If user is logged in, passport.js will create user object in req for every request in express.js, which you can check for existence in any middleware:
if (req.user) {
// logged in
} else {
// not logged in
}
You ca...
Cost of exception handlers in Python
... another question , the accepted answer suggested replacing a (very cheap) if statement in Python code with a try/except block to improve performance.
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Check if array is empty or null
I would like to know how to check if an array is empty or null in jQuery. I tried array.length === 0 but it didn't work. It did not throw any error either.
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Is an entity body allowed for an HTTP DELETE request?
...hen issuing an HTTP DELETE request, the request URI should completely identify the resource to delete. However, is it allowable to add extra meta-data as part of the entity body of the request?
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