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What's an easy way to read random line from a file in Unix command line?
...
You can use shuf:
shuf -n 1 $FILE
There is also a utility called rl. In Debian it's in the randomize-lines package that does exactly what you want, though not available in all distros. On its home page it actually recommends the use of shuf instead (which didn't exist when it was c...
What is mutex and semaphore in Java ? What is the main difference?
...monitor built into every object, which is also similar to the Win32 object called a Mutex. The same applies to a ReentrantLock. All of these are recursive. I am not aware of any "real-world" examples of non-recursive mutexes (I have seen them only in textbooks) so I did not consider them.
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Is it better to use Enumerable.Empty() as opposed to new List() to initialize an IEnumerable
...ould be noticeable impact.
Enumerable.Empty does not create an object per call thus putting less load on GC.
If the code is in low-throughput location, then it boils down to aesthetic considerations though.
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Using a .php file to generate a MySQL dump
...s can be done by the command itself.
That external command will :
be a call to mysqldump, with the right parameters,
and redirect the output to a file.
For example :
mysqldump --user=... --password=... --host=... DB_NAME > /path/to/output/file.sql
Which means your PHP code would look l...
Insert new item in array on any position in PHP
...
You may find this a little more intuitive. It only requires one function call to array_splice:
$original = array( 'a', 'b', 'c', 'd', 'e' );
$inserted = array( 'x' ); // not necessarily an array, see manual quote
array_splice( $original, 3, 0, $inserted ); // splice in at position 3
// $original...
How do arrays in C# partially implement IList?
...s.
But the CLR creates concrete array types on the fly, so it could technically create one that implements these interfaces. This is however not the case. Try this code for example:
using System;
using System.Collections.Generic;
class Program {
static void Main(string[] args) {
var...
Identify duplicates in a List
... look if the frequency of this object is more than once in your list.
Then call .distinct() to only have unique elements in your result
result = original.stream()
.filter(e -> Collections.frequency(original, e) > 1)
.distinct()
.collect(Collectors.toList());
// returns {1,3}
// re...
Automatically import modules when entering the python or ipython interpreter
...How do I set up the python or ipython interpreter so that numpy is automatically imported?
8 Answers
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Passing multiple variables in @RequestBody to a Spring MVC controller using Ajax
...r passing multiple object, params, variable and so on. You can do it dynamically using ObjectNode from jackson library as your param. You can do it like this way:
@RequestMapping(value = "/Test", method = RequestMethod.POST)
@ResponseBody
public boolean getTest(@RequestBody ObjectNode objectNode) {...
How to open an elevated cmd using command line for Windows?
... here
Method 1: WITHOUT a 3rd party program (I used this)
Create a file called sudo.bat (you can replace sudo with any name you want) with following content
powershell.exe -Command "Start-Process cmd \"/k cd /d %cd%\" -Verb RunAs"
Move sudo.bat to a folder in your PATH; if you don't know what t...