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how perform grep operation on all files in a directory
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grep $PATTERN * would be sufficient. By default, grep would skip all subdirectories. However, if you want to grep through them, grep -r $PATTERN * is the case.
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How do I select elements of an array given condition?
... (x > 1) & (x < 5) forces the inequalities to evaluate first, so all of the operations occur in the intended order and the results are all well-defined. See docs here.
– calavicci
Nov 16 '17 at 17:58
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How do I copy an object in Java?
...oes for primitives. For non-primitives, you would just do copy contructor call recursively. e.g. If DummyBean referenced FooBar then FooBar should have contructor FooBar(FooBar another), and dummy should call this.foobar = new FooBar(another.foobar)
– egaga
Feb...
Does JavaScript guarantee object property order?
...insertion)
As a note, properties order in objects weren’t guaranteed at all before ES2015. Definition of an Object from ECMAScript Third Edition (pdf):
4.3.3 Object
An object is a member of the
type Object. It is an unordered collection of properties each of which
contains a primitive value, obj...
FIND_IN_SET() vs IN()
...FROM orders
CROSS JOIN
(
SELECT 1 AS pos
UNION ALL
SELECT 2 AS pos
UNION ALL
SELECT 3 AS pos
UNION ALL
SELECT 4 AS pos
UNION ALL
SELECT 5 AS pos
) q
JOIN company
ON companyID = CAST(NULLIF(SUBSTRI...
How to design a product table for many kinds of product where each product has many parameters
...the type hierarchy you describe:
Single Table Inheritance: one table for all Product types, with enough columns to store all attributes of all types. This means a lot of columns, most of which are NULL on any given row.
Class Table Inheritance: one table for Products, storing attributes common to...
How do I exit the Vim editor?
...ite if there are changes)
:exit to write and exit (same as :x)
:qa to quit all (short for :quitall)
:cq to quit without saving and make Vim return non-zero error (i.e. exit with error)
You can also exit Vim directly from "Normal mode" by typing ZZ to save and quit (same as :x) or ZQ to just quit (...
Advantages of Binary Search Trees over Hash Tables
... instance, if a hash function has a range R(h) = 0...100, then you need to allocate an array of 100 (pointers-to) elements, even if you are just hashing 20 elements. If you were to use a binary search tree to store the same information, you would only allocate as much space as you needed, as well as...
Haskell, Lisp, and verbosity [closed]
...y general that it never gets in your way, and somewhat surprisingly it actually "aids in achieving agility" (as you said) because when your program compiles you can be almost certain that is correct, so this certainty lets you try out things you might be otherwise afraid to try -- there is a "dynami...
Get OS-level system information
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You can get some limited memory information from the Runtime class. It really isn't exactly what you are looking for, but I thought I would provide it for the sake of completeness. Here is a small example. Edit: You can also get disk usage information from the java.io.File class. The disk space us...
