Tutorial by Examples: e

Many commands and programs in the remote side are screen-based (e.g. mc) or they need to ask password (e.g. sudo), to be able to run these kind of programs you can use option -t. ssh -t [email protected] sudo ls / [sudo] password for alice: bin root dev etc home lib mnt opt proc root run usr ...

Fabric is a Python (2.5-2.7) library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks. It lets you execute arbitrary Python functions via the command line. Install fabric via pip install fabric Create fabfile.py in your root directory...

The following simple procedure displays the text "Hello World" in a client that supports dbms_output. CREATE OR REPLACE PROCEDURE helloworld AS BEGIN dbms_output.put_line('Hello World!'); END; / You need to execute this at the SQL prompt to create the procedure in the database,...

set serveroutput on DECLARE message constant varchar2(32767):= 'Hello, World!'; BEGIN dbms_output.put_line(message); END; / Command set serveroutput on is required in SQL*Plus and SQL Developer clients to enable the output of dbms_output. Without the command nothing is displayed. T...

Django handles a request by routing the incoming URL path to a view function. The view function is responsible for returning a response back to the client making the request. Different URLs are usually handled by different view functions. To route the request to a specific view function, Django look...

A simple hello world grammar can be found here: // define a grammar called Hello grammar Hello; r : 'hello' ID; ID : [a-z]+ ; WS : [ \t\r\n]+ -> skip ; To build this .g4 sample you can run the following command from your operating systems terminal/command-line: Java -jar antlr-4.5.3-...

foldMap maps each element of the Foldable structure to a Monoid, and then combines them into a single value. foldMap and foldr can be defined in terms of one another, which means that instances of Foldable need only give a definition for one of them. class Foldable t where foldMap :: Monoid m...

// Twitter markup documentation: // https://dev.twitter.com/cards/markup String[] twitterTags = { "twitter:site", "twitter:site:id", "twitter:creator", "twitter:creator:id", &q...

For added safety we can define the type of object that the array contains: NSArray<NSString *> *colors = @[@"Red", @"Green", @"Blue", @"Yellow"]; NSMutableArray<NSString *> *myColors = [NSMutableArray arrayWithArray:colors]; [myColors addObject:...

NSArray *myColors = @[@"Red", @"Green", @"Blue", @"Yellow"]; [myColors enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) { NSLog(@"enumerating object %@ at index %lu", obj, idx); }]; By setting the stop parameter to YES you c...

As parameters (8, 16, 32 bits) 8, 16, 32 bits integers are always passed, on the stack, as full width 32 bits values1. No extension, signed or zeroed, is needed. The callee will just use the lower part of the full width values. //C prototype of the callee void __attribute__((cdecl)) foo(char ...

As parameters (float, double) Floats are 32 bits in size, they are passed naturally on the stack. Doubles are 64 bits in size, they are passed, on the stack, respecting the Little Endian convention1, pushing first the upper 32 bits and than the lower ones. //C prototype of callee double foo(dou...

The clear property is directly related to floats. Property Values: none - Default. Allows floating elements on both sides left - No floating elements allowed on the left side right - No floating elements allowed on the right side both - No floating elements allowed on either the left or the r...

This is a very common workflow when using Ansible for provisioning an AWS EC2 instance. This post assumes a basic understand of Ansible and most importantly, assumes you've properly configured it to connect to AWS. As Ansible official documentation insists, we are going to use four roles: 1- ami_f...

Managing AWS resources that scale up and down runs into the limits of the static inventory host file, that's why we need something dynamic. And that's what the dynamic inventories are for. Let's start: Download these ec2.ini and ec2.py files to the your project folder: cd my_ansible_project wget...

There is a maximum capacity an integer can store. And when you go over that limit, it will loop back to the negative side. For int, it is 2147483647 int x = int.MaxValue; //MaxValue is 2147483647 x = unchecked(x + 1); //make operation explicitly unchecked so that the ...

Overflow also happens during the operation. In the following example, x is an int, 1 is an int by default. Therefore addition is an int addition. And the result will be an int. And it will overflow. int x = int.MaxValue; //MaxValue is 2147483647 long y = x + 1; //...

If you are using multiple namespaces that may have same-name classes(such as System.Random and UnityEngine.Random), you can use an alias to specify that Random comes from one or the other without having to use the entire namespace in the call. For instance: using UnityEngine; using System; Ran...

Built in functions can subset rows with columns that meet conditions. df <- data.frame(item = c(1:10), price_Elasticity = c(-0.57667, 0.03205, -0.04904, 0.10342, 0.04029, 0.0742, 0.1669, 0.0313, 0.22204, 0.06158), total...

Create a file named SCALA_PROJECT/build.gradle with these contents: group 'scala_gradle' version '1.0-SNAPSHOT' apply plugin: 'scala' repositories { jcenter() mavenCentral() maven { url "https://repo.typesafe.com/typesafe/maven-releases" } } dep...