Tutorial by Examples: s

Expires — specifies date when the resource becomes stale. It relies on servers and clients having accurate clocks and supporting time zones correctly. Cache-control: max-age takes precedence over Expires, and is generally more reliable. post-check and pre-check directives are non-standard I...

Single Pointers Pointer to an int The pointer can point to different integers and the int's can be changed through the pointer. This sample of code assigns b to point to int b then changes b's value to 100. int b; int* p; p = &b; /* OK */ *p = 100; /* OK */ Pointer to a cons...

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...

CREATE [OR REPLACE] PROCEDURE procedure_name [(parameter_name [IN | OUT | IN OUT] type [, ...])] {IS | AS} < declarations > BEGIN < procedure_body > EXCEPTION -- Exception-handling part begins <exception handling goes here > WHEN exception1 THE...

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...

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...

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 ...

Python provides functions for justifying strings, enabling text padding to make aligning various strings much easier. Below is an example of str.ljust and str.rjust: interstates_lengths = { 5: (1381, 2222), 19: (63, 102), 40: (2555, 4112), 93: (189,305), } for road, length in...

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...

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...

Over time, our classes may implement more and more interfaces. When these interfaces have many methods, the total number of methods in our class will become very large. For example, let's suppose that we have two interfaces and a class implementing them: interface Printable { public functio...

To install an APK file, use the following command: adb install path/to/apk/file.apk or if the app is existing and we want to reinstall adb install -r path/to/apk/file.apk To uninstall an application, we have to specify its package adb uninstall application.package.name Use the following...

import cv2 image_path= #put your image path here #use imread() function to read image data to variable img. img = cv2.imread(image_path) #display image data in a new window with title 'I am an image display window' cv2.imshow('I am an image display window',img) #wait until user hi...

Java Logging Api has 7 levels. The levels in descending order are: SEVERE (highest value) WARNING INFO CONFIG FINE FINER FINEST (lowest value) The default level is INFO (but this depends on the system and used a virtual machine). Note: There are also levels OFF (can be used to turn log...