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What's a concise way to check that environment variables are set in a Unix shell script?
...is therefore in the Korn Shell, and in the POSIX shells, including specifically Bash.
It is usually documented in the shell's man page in a section called Parameter Expansion. For example, the bash manual says:
${parameter:?word}
Display Error if Null or Unset. If parameter is null or unset, the...
How do I unset an element in an array in javascript?
How do I remove the key 'bar' from an array foo so that 'bar' won't show up in
6 Answers
...
Accessing items in an collections.OrderedDict by index
...ort collections
>>> d = collections.OrderedDict()
>>> d['foo'] = 'python'
>>> d['bar'] = 'spam'
>>> d.items()
[('foo', 'python'), ('bar', 'spam')]
>>> d.items()[0]
('foo', 'python')
>>> d.items()[1]
('bar', 'spam')
Note for Python 3.X
dict.ite...
Why is extending native objects a bad practice?
...ody does it "the wrong way", and adds enumerable types to Object , practically destroying all loops on any object?
8 Answe...
How to get the filename without the extension in Java?
...me, would rather use some library code where they probably have thought of all special cases, such as what happens if you pass in null or dots in the path but not in the filename, you can use the following:
import org.apache.commons.io.FilenameUtils;
String fileNameWithOutExt = FilenameUtils.remove...
Custom Python list sorting
...ter alternative to implement the same sorting:
alist.sort(key=lambda x: x.foo)
Or alternatively:
import operator
alist.sort(key=operator.attrgetter('foo'))
Check out the Sorting How To, it is very useful.
share
...
How to create dictionary and add key–value pairs dynamically?
...
});
// repeat this last part as needed to add more key/value pairs
Basically, you're creating an object literal with 2 properties (called key and value) and inserting it (using push()) into the array.
Edit: So almost 5 years later, this answer is getting downvotes because it's not creating an ...
What is `git diff --patience` for?
...nly considers the longest common subsequence of the signature lines:
Find all lines which occur exactly once on both sides, then do longest common subsequence on those lines, matching them up.
When should you use patience diff? According to Bram, patience diff is good for this situation:
The re...
How can I include raw JSON in an object using Jackson?
...e reverse direction is a bit trickier to handle. In effect it was added to allow injecting pre-encoded content.
I guess it would be possible to add support for reverse, although that would be quite awkward: content will have to be parsed, and then re-written back to "raw" form, which may or may not...
How to forward declare a C++ template class?
...
I disagree. The standard says: "A template-parameter shall not be given default arguments by two different declarations in the same scope". And I found nothing about defaults in the first declaration only. Also the code with the forward declaration and defaults in the definition ...