Tutorial by Examples: l

Outputs the line number in the current script. Mostly useful when debugging scripts. #!/bin/bash # this is line 2 echo something # this is line 3 echo $LINENO # Will output 4

OLDPWD (OLDPrintWorkingDirectory) contains directory before the last cd command: ~> $ cd directory directory> $ echo $OLDPWD /home/user

A readonly list of the options bash is supplied on startup to control its behaviour: ~> $ echo $SHELLOPTS braceexpand:emacs:hashall:histexpand:history:interactive-comments:monitor

When the bash command is executed a new shell is opened. The $SHLVL environment variable holds the number of shell levels the current shell is running on top of. In a new terminal window, executing the following command will produce different results based on the Linux distribution in use. echo $S...

LINQ provides a built-in function for checking the equality of two IEnumerables, and that function can be used on arrays. The SequenceEqual function will return true if the arrays have the same length and the values in corresponding indices are equal, and false otherwise. int[] arr1 = { 3, 5, 7 };...

Consider this example function to check if a host is up: is_alive() { ping -c1 "$1" &> /dev/null } This function sends a single ping to the host specified by the first function parameter. The output and error output of ping are both redirected to /dev/null, so the functi...

Decorator is one of structural design patterns. It is used to add, remove or change behaviour of object. This document will teach you how to use Decorator DP properly. Let me explain the idea of it to you on a simple example. Imagine you're now in Starbobs, famous coffee company. You can place an o...

sudo -s <<EOF a='var' echo 'Running serveral commands with sudo' mktemp -d echo "\$a" EOF $a needs to be escaped to prevent it to be expanded by the current shell Or sudo -s <<'EOF' a='var' echo 'Running serveral commands with sudo' mktemp -d e...

Detailed instructions on getting google-bigquery set up or installed.

Inside your layout, add a Login button with the following code: <com.twitter.sdk.android.core.identity.TwitterLoginButton android:id="@+id/twitter_login_button" android:layout_width="wrap_content" android:layout_height="wrap_content" and...

The class use Phalcon\Validation\Validator; use Phalcon\Validation\ValidatorInterface; use Phalcon\Validation\Message; class RecaptchaValidator extends Validator implements ValidatorInterface { public function validate(\Phalcon\Validation $validation, $attribute) { $value =...

Registers: 8 bit: A, B, C, D, E, H, L, F, I, R, 16 bit: SP, PC, IX, IY, and shadows of some 8b registers: A', B', C', D', E', H', L' and F'. Most of the 8 bit registers can be used also in pairs as 16 bit registers: AF, BC, DE and HL. SP is stack pointer, marking the bottom of stack memory (used b...

You can find description of the driver here. The quick example is: import psycopg2 db_host = 'postgres.server.com' db_port = '5432' db_un = 'user' db_pw = 'password' db_name = 'testdb' conn = psycopg2.connect("dbname={} host={} user={} password={}".format( ...

In order to determine some simple statistics of a value in a column of a table, you can use an aggregate function. If your individuals table is: NameAgeAllie17Amanda14Alana20 You could write this statement to get the minimum, maximum and average value: SELECT min(age), max(age), avg(age) FROM i...

In order to use Gson you have to include it in your project. You can do this by adding the following dependency of the Gson version available in Maven Central: Maven Add to pom.xml <dependencies> <dependency> <groupId>com.google.code.gson</groupId> <a...

C++ compilers encode additional information in the names of exported functions, such as argument types, to make overloads with different arguments possible. This process is called name mangling. This causes problems with importing functions in C# (and interop with other languages in general), as the...

There're several conventions of calling functions, specifying who (caller or callee) pops arguments from the stack, how arguments are passed and in what order. C++ uses Cdecl calling convention by default, but C# expects StdCall, which is usually used by Windows API. You need to change one or the ot...

foo = "bar" foo[0] = "c" # Error Immutable variable value can not be changed once they are created.

foo = ("bar", 1, "Hello!",) foo[1] = 2 # ERROR!! Second line would return an error since tuple members once created aren't assignable. Because of tuple's immutability.

In Solution Explorer go to your project, right click on References then Add reference… Search for Compression and select System.IO.Compression.FileSystem then press OK. Add Imports System.IO.Compression to the top of your code file (before any class or module, with the other Imports statements)....