Tutorial by Examples: d

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...

ssh -p 21 [email protected] <<EOF echo 'printing pwd' echo "\$(pwd)" ls -a find '*.txt' EOF $ is escaped because we do not want it to be expanded by the current shell i.e $(pwd) is to be executed on the remote shell. Another way: ssh -p 21 [email protected] <...

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...

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 =...

Things you need A paid Apple Developer Program Membership A valid App ID and identifier for you app (like com.example.MyApp) which is not used before anywhere Access to developer.apple.com and Member Center An iOS Device to test (as Push Notifications don't work on Simulator) Enabling t...

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.

Each time this parameter is referenced, a random integer between 0 and 32767 is generated. Assigning a value to this variable seeds the random number generator (source). ~> $ echo $RANDOM 27119 ~> $ echo $RANDOM 1349

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)....

Eventually, when you're ready to release a version of your code to production, you'll need a .jar file to distribute. Intellij makes building JARs quite easy. First, navigate to File -> Project Structure and click on Artifacts: Click on the + button, and select JAR -> From modules with dep...

Windows in SFML are represented by one of two classes: sf::Window is a generic window provided by the operating system including an OpenGL render context. sf::RenderWindow is a specialized version of sf::Window that also acts as a sf::RenderTarget, allowing SFML's primitives to be rendered to it...

You can set any function for debugging with debug. debug(mean) mean(1:3) All subsequent calls to the function will enter debugging mode. You can disable this behavior with undebug. undebug(mean) mean(1:3) If you know you only want to enter the debugging mode of a function once, consider t...

On systems that use the System-V style init scripts, such as RHEL/CentOS 6: service <service> start service <service> stop On systems using systemd, such as Ubuntu (Server and Desktop) >= 15.04, and RHEL/CentOS >= 7: systemctl <service> dnsmasq systemctl <service> ...

On systems using systemd, such as Fedora => 15, Ubuntu (Server and Desktop) >= 15.04, and RHEL/CentOS >= 7: systemctl status [servicename] ...where [servicename] is the service in question; for example, systemctl status sshd. This will show basic status information and any recent errors ...

ADO.NET Connections are one of the simplest ways to connect to a database from a C# application. They rely on the use of a provider and a connection string that points to your database to perform queries against. Common Data Provider Classes Many of the following are classes that are commonly used...

You can combine named arguments with optional parameters. Let see this method: public sealed class SmsUtil { public static bool SendMessage(string from, string to, string message, int retryCount = 5, object attachment = null) { // Some code } } When you want to call t...

You can place named arguments in any order you want. Sample Method: public static string Sample(string left, string right) { return string.Join("-",left,right); } Call Sample: Console.WriteLine (Sample(left:"A",right:"B")); Console.WriteLine (Sample(right...

Date and time without time zone information LocalDateTime dateTime = LocalDateTime.of(2016, Month.JULY, 27, 8, 0); LocalDateTime now = LocalDateTime.now(); LocalDateTime parsed = LocalDateTime.parse("2016-07-27T07:00:00"); Date and time with time zone information ZoneId zoneId = Zon...

LocalDate tomorrow = LocalDate.now().plusDays(1); LocalDateTime anHourFromNow = LocalDateTime.now().plusHours(1); Long daysBetween = java.time.temporal.ChronoUnit.DAYS.between(LocalDate.now(), LocalDate.now().plusDays(3)); // 3 Duration duration = Duration.between(Instant.now(), ZonedDateTime.par...