.NET Core is a cross-platform version of .NET for building websites, services, and console applications. .NET Core SDK allows you to develop apps with .NET Core.

Install .Net Core SDK

Depending on the version of Ubuntu that you have, choose corresponding commands to run.

Run below commands to install .Net Core SDK 2.1 on Ubuntu 16.04:

{
  wget https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
  sudo dpkg -i packages-microsoft-prod.deb
  sudo apt-get update
  sudo apt-get install -y apt-transport-https
  sudo apt-get update
  sudo apt-get install -y dotnet-sdk-2.1
}

Run below commands to install .Net core SDK 2.1 on Ubuntu 18.04:

{
  wget https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
  sudo dpkg -i packages-microsoft-prod.deb
  sudo apt-get update
  sudo apt-get install -y apt-transport-https
  sudo apt-get update
  sudo apt-get install -y dotnet-sdk-2.1
}

Create new console application

Run below command to create new console application with name hellodotnet:

dotnet new console -o hellodotnet

Sample output:

The template "Console Application" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on hellodotnet/hellodotnet.csproj...
  Restore completed in 438.13 ms for /home/testuser/hellodotnet/hellodotnet.csproj.

Restore succeeded.

A new directory hellodotnet will be created with default Console Application template.

Edit hellodotnet/Program.cs and update message from Hello World! to Hello .Net Core!.

Run the application

To run the application with default settings i.e. Debug configuration, run below command inside hellodotnet directory:

dotnet run

Sample output:

Hello .Net Core!

Build the application with specific configuration

To build the project in Release configuration, run below command inside hellodotnet directory:

dotnet build --configuration Release

Above command does not run the application, it only build a project and all of its dependencies.

Sample output:

Microsoft (R) Build Engine version 16.2.37902+b5aaefc9f for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 96.51 ms for /home/testuser/hellodotnet/hellodotnet.csproj.
  hellodotnet -> /home/testuser/hellodotnet/bin/Release/netcoreapp2.1/hellodotnet.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:02.26

To build the project in Debug configuration, run below command inside hellodotnet directory:

dotnet build --configuration Debug

Publish the application

Before you want to deploy this application on a hosting system, you need to publish it.

The output includes the following assets:

  • Intermediate Language (IL) code in an assembly with a dll extension.
  • A .deps.json file that includes all of the dependencies of the project.
  • A .runtimeconfig.json file that specifies the shared runtime that the application expects, as well as other configuration options for the runtime (for example, garbage collection type).
  • The application’s dependencies, which are copied from the NuGet cache into the output folder.

To do the same, dotnet publish requires to be run like below:

dotnet publish --configuration Release

Sample output:

Microsoft (R) Build Engine version 16.2.37902+b5aaefc9f for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 382.94 ms for /home/testuser/hellodotnet/hellodotnet.csproj.
  hellodotnet -> /home/testuser/hellodotnet/bin/Release/netcoreapp2.1/hellodotnet.dll
  hellodotnet -> /home/testuser/hellodotnet/bin/Release/netcoreapp2.1/publish/

Following files will be available in the publish dirctory:

hellodotnet.deps.json  hellodotnet.dll  hellodotnet.pdb  hellodotnet.runtimeconfig.json

Hosting system need to have .Net Core 2.1 runtime installed to run the application with below command:

dotnet hellodotnet.dll

Publish self-contained application

It is possible to publish application as self-contained. Doing so also publishes the .NET Core runtime with your application so the runtime doesn’t need to be installed on the target machine.

To create a self-contained along with runtime identifier for Linux x64 (Most desktop distributions like CentOS, Debian, Fedora, Ubuntu, and derivatives), run below command:

dotnet publish --configuration Release --self-contained true --runtime linux-x64

Sample output:

Microsoft (R) Build Engine version 16.2.37902+b5aaefc9f for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 16.5 sec for /home/testuser/hellodotnet/hellodotnet.csproj.
  hellodotnet -> /home/testuser/hellodotnet/bin/Release/netcoreapp2.1/linux-x64/hellodotnet.dll
  hellodotnet -> /home/testuser/hellodotnet/bin/Release/netcoreapp2.1/linux-x64/publish/

You will need to distribute all the files under publish directory to the hosting system.

A platform specific executable will also be created in the publish directory which you can use to run your application directory like below:

./hellodotnet

## Output
Hello .Net Core!

Please check Microsoft webesite under References section below to get list of runtime identifier for other supported OSes.

References: