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Checking from shell script if a directory contains files
From a shell script, how do I check if a directory contains files?
26 Answers
26
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Checking if sys.argv[x] is defined
What would be the best way to check if a variable was passed along for the script:
8 Answers
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If table exists drop table then create it, if it does not exist just create it
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Just put DROP TABLE IF EXISTS `tablename`; before your CREATE TABLE statement.
That statement drops the table if it exists but will not throw an error if it does not.
s...
Inverse dictionary lookup in Python
...as a .index method on lists the returns the first found index with the specified value or an exception if not found... any reason why such a semantic could not be applied to dictionaries?
– Brian Jack
Jun 22 '12 at 15:27
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How do I get the application exit code from a Windows command line?
...nning a program and want to see what its return code is (since it returns different codes based on different errors).
7 Ans...
Is the ternary operator faster than an “if” condition in Java [duplicate]
I am prone to " if-conditional syndrome " which means I tend to use if conditions all the time. I rarely ever use the ternary operator. For instance:
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How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
.... [a-z] matches any single lower case letter of the alphabet.
() Groups different matches for return purposes. See examples below.
{} Multiplier for repeated copies of pattern defined before it.
E.g. [a]{2} matches two consecutive lower case letter a: aa
E.g. [a]{1,3} matches at least one and ...
How to exit if a command failed?
...am a noob in shell-scripting. I want to print a message and exit my script if a command fails. I've tried:
8 Answers
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Removing all empty elements from a hash / YAML?
...dd a compact method to Hash like this
class Hash
def compact
delete_if { |k, v| v.nil? }
end
end
or for a version that supports recursion
class Hash
def compact(opts={})
inject({}) do |new_hash, (k,v)|
if !v.nil?
new_hash[k] = opts[:recurse] && v.class == Hash...
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...