Tutorial by Examples: g

Redirecting standard output

> redirect the standard output (aka STDOUT) of the current command into a file or another descriptor. These examples write the output of the ls command into the file file.txt ls >file.txt > file.txt ls The target file is created if it doesn't exists, otherwise this file is truncated. ...

Bash • Redirection

Redirecting STDIN

< reads from its right argument and writes to its left argument. To write a file into STDIN we should read /tmp/a_file and write into STDIN i.e 0</tmp/a_file Note: Internal file descriptor defaults to 0 (STDIN) for < $ echo "b" > /tmp/list.txt $ echo "a" >> ...

Bash • Redirection

Redirecting both STDOUT and STDERR

File descriptors like 0 and 1 are pointers. We change what file descriptors point to with redirection. >/dev/null means 1 points to /dev/null. First we point 1 (STDOUT) to /dev/null then point 2 (STDERR) to whatever 1 points to. # STDERR is redirect to STDOUT: redirected to /dev/null, # effect...

Bash • Redirection

Redirecting STDERR

2 is STDERR. $ echo_to_stderr 2>/dev/null # echos nothing Definitions: echo_to_stderr is a command that writes "stderr" to STDERR echo_to_stderr () { echo stderr >&2 } $ echo_to_stderr stderr

Bash • Redirection

Strings

The type of the literal Without any extensions, the type of a string literal – i.e., something between double quotes – is just a string, aka list of characters: Prelude> :t "foo" "foo" :: [Char] However, when the OverloadedStrings extension is enabled, string literals be...

Haskell Language • Overloaded Literals

Registering New Elements

Defines an <initially-hidden> custom element which hides its contents until a specified number of seconds have elapsed. const InitiallyHiddenElement = document.registerElement('initially-hidden', class extends HTMLElement { createdCallback() { this.revealTimeoutId = null; } at...

JavaScript • Custom Elements

Extending Native Elements

It's possible to extent native elements, but their descendants don't get to have their own tag names. Instead, the is attribute is used to specify which subclass an element is supposed to use. For example, here's an extension of the <img> element which logs a message to the console when it's l...

JavaScript • Custom Elements

Compiling with GCC

Assuming a single source file named main.cpp, the command to compile and link an non-optimized executable is as follows (Compiling without optimization is useful for initial development and debugging, although -Og is officially recommended for newer GCC versions). g++ -o app -Wall main.cpp -O0 T...

C++ • Compiling and Building

Get Started in Xamarin Studio

Browse to File > New > Solution to bring you up the new project dialog Select Single View App and press Next Configure your app by setting your app name and organization ID, and press Next: Set your Project name and Solution name, or leave as the default name. Click Create to create...

Xamarin.iOS • Getting started with Xamarin.iOS

Float an Image Within Text

The most basic use of a float is having text wrap around an image. The below code will produce two paragraphs and an image, with the second paragraph flowing around the image. Notice that it is always content after the floated element that flows around the floated element. HTML: <p>Lorem ips...

CSS • Floats

Event Bubbling and Capturing

Events fired on DOM elements don't just affect the element they're targeting. Any of the target's ancestors in the DOM may also have a chance to react to the event. Consider the following document: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> </hea...

DOM • Events

Checking arithmetic with assert

a = 1 - Math.abs(1 - a % 2); // This will throw an error if my arithmetic above is wrong. assert a >= 0 && a <= 1 : "Calculated value of " + a + " is outside of expected bounds"; return a;

Java Language • Asserting

Downloading a file via curl

This downloads a file from the Dropbox API at the remote path /Homework/math/Prime_Numbers.txt to the local path Prime_Numbers.txt in the current folder: curl -X POST https://content.dropboxapi.com/2/files/download \ --header "Authorization: Bearer <ACCESS_TOKEN>" \ --head...