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How to tell if a string is not defined in a Bash shell script
... not set, you can use:
if [ -z "${VAR+xxx}" ]; then echo VAR is not set at all; fi
if [ -z "$VAR" ] && [ "${VAR+xxx}" = "xxx" ]; then echo VAR is set but empty; fi
You probably can combine the two tests on the second line into one with:
if [ -z "$VAR" -a "${VAR+xxx}" = "xxx" ]; then echo VA...
Do I need all three constructors for an Android custom view?
...s/MyCustomStyle"
...
/>
the 2nd constructor will also be called and default the style to MyCustomStyle before applying explicit XML attributes.
The third constructor is usually used when you want all of the Views in your application to have the same style.
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Printing the value of a variable in SQL Developer
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Make server output on First of all
SET SERVEROUTPUT on then
Go to the DBMS Output window (View->DBMS Output)
then Press Ctrl+N for connecting server
share
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How do I list all the columns in a table?
For the various popular database systems, how do you list all the columns in a table?
12 Answers
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Extracting an attribute value with beautifulsoup
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.find_all() returns list of all found elements, so:
input_tag = soup.find_all(attrs={"name" : "stainfo"})
input_tag is a list (probably containing only one element). Depending on what you want exactly you either should do:
out...
What are enums and why are they useful?
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You should always use enums when a variable (especially a method parameter) can only take one out of a small set of possible values. Examples would be things like type constants (contract status: "permanent", "temp", "apprentice"), or flags ("execute now", "defer execution")....
Does a javascript if statement with multiple conditions test all of them?
...statement with multiple conditions to test for, does javascript test them all regardless, or will it bail before testing them all if it's already false?
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How can I search sub-folders using glob.glob module?
...er(files, '*.txt')]
This'll walk your directories recursively and return all absolute pathnames to matching .txt files. In this specific case the fnmatch.filter() may be overkill, you could also use a .endswith() test:
import os
path = 'C:/Users/sam/Desktop/file1'
configfiles = [os.path.join(di...
sql query to return differences between two tables
...g to compare two tables, SQL Server, to verify some data. I want to return all the rows from both tables where data is either in one or the other. In essence, I want to show all the discrepancies. I need to check three pieces of data in doing so, FirstName, LastName and Product.
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How to .gitignore all files/folder in a folder, but not the folder itself? [duplicate]
... something in it, even just an empty file.
For example, add an empty file called .gitkeep to the folder you want to keep, then in your .gitignore file write:
# exclude everything
somefolder/*
# exception to the rule
!somefolder/.gitkeep
Commit your .gitignore and .gitkeep files and this should re...