Follow the below steps to run your application:

1. Publish your application as a self contained application:

        dotnet publish -c release -r ubuntu.16.04-x64 --self-contained

2. Copy the `publish` folder to the Ubuntu machine

3. Open the Ubuntu machine terminal (CLI) and go to the project directory

4. Provide execute permissions:

        chmod 777 ./appname

5. Execute the application

        ./appname




I&#39;ve setup the environment for react native on Windows. But when I run the command 

    react-native run-android

 
I get the following errors -

    * What went wrong:
    A problem occurred configuring project &#39;:app&#39;.
    &gt; Failed to notify project evaluation listener.
       &gt; Could not initialize class com.android.sdklib.repository.AndroidSdkHandler

How do I fix this?

Error: Could not initialize class com.android.sdklib.repository.AndroidSdkHandler

In CKEditor 4 to change the editor height there was a configuration option: [config.height][1]. 

How do I change the height of CKEditor 5? (the Classic Editor)


  [1]: http://docs.ckeditor.com/#!/api/CKEDITOR.config-cfg-height

How to set the height of CKEditor 5 (Classic Editor)

I am using Visual Studio 2015 and created a .NET Core console application. After compiling, I have my project DLL file in the *debug* folder. And if I want to run it on another computer, I have to install .NET on it and then write `dotnet myApp.dll` in command window (CMD). But I need to run my application without any installations.

I have read that I must publish my application. I do it with the command `dotnet publish -c Release`. Now in folder *release* I have a new folder, *publish*, with myApp.dll and other dll-files and folder runtimes for different systems. For example, in the *Ubuntu.16.04-x64* folder I have file *System.Security.Cryptography.Native.OpenSsl.so*. But how can I run my application without any new installations of .NET or something else?





How to run a .NET Core console application on Linux

I am using Visual Studio 2015 and created a .NET Core console application. After compiling, I have my project DLL file in the debug folder. And if I want to run it on another computer, I have to install .NET on it and then write <code>dotnet myApp.dll</code> in command window (CMD). But I need to run my application without any installations.
I have read that I must publish my application. I do it with the command <code>dotnet publish -c Release</code>. Now in folder release I have a new folder, publish, with myApp.dll and other dll-files and folder runtimes for different systems. For example, in the Ubuntu.16.04-x64 folder I have file System.Security.Cryptography.Native.OpenSsl.so. But how can I run my application without any new installations of .NET or something else?

**How can I call SignalR Core Hub method from Controller?**  
I am using  ASP.NET Core 2.0 with Microsoft.AspNetCore.SignalR (1.0.0-alpha2-final).

I have windows service which communicate with Excel, SolidEdge ... When operation is complete it post request to my controller in ASP.NET Core application. Now I need to inform all clients connected to server with SignalR that external program completed some task.  
I can not change the way window service works. (Can not connect to SignalR from window service).  
I found plenty solution for old SignalR (`GlobalHost.ConnectionManager.GetHubContext`), but much has changed and those solutions are not working anymore.

My controller:

    [Route(&quot;API/vardesigncomm&quot;)]
    public class VarDesignCommController : Controller
    {
        [HttpPut(&quot;ProcessVarDesignCommResponse/{id}&quot;)]
        public async Task&lt;IActionResult&gt; ProcessVarDesignCommResponse(int id)
        {
            //call method TaskCompleted in Hub !!!! How?
     
            return new JsonResult(true);
        }
    }

My hub:

    public class VarDesignHub : Hub
    {
        public async Task TaskCompleted(int id)
        {
            await Clients.All.InvokeAsync(&quot;Completed&quot;, id);
        }
    }




Call SignalR Core Hub method from Controller

In my ASP.NET Core application, I get the following error:

&gt; InvalidOperationException: Unable to resolve service for type &#39;Cities.Models.IRepository&#39; while attempting to activate &#39;Cities.Controllers.HomeController&#39;.

I the `HomeController` I am trying to pass the `Cities` getter to the view like so:

``` c#
public class HomeController : Controller
{
    private readonly IRepository repository;

    public HomeController(IRepository repo) =&gt; repository = repo;

    public IActionResult Index() =&gt; View(repository.Cities);
}
```


I have one file `Repository.cs` that contains an interface and its implementation like so:

``` c#
public interface IRepository
{
    IEnumerable&lt;City&gt; Cities { get; }
    void AddCity(City newCity);
}

public class MemoryRepository : IRepository
{
    private readonly List&lt;City&gt; cities = new List&lt;City&gt;();

    public IEnumerable&lt;City&gt; Cities =&gt; cities;

    public void AddCity(City newCity) =&gt; cities.Add(newCity);
}
```

My `Startup` class contains the default-generated code from the template. I have made any changes:

``` c#
public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllersWithViews();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        ...
    }
}
```

Unable to resolve service for type while attempting to activate

Not sure what am I missing here but I am not able to get the values from my appsettings.json in my .net core application. I have my appsettings.json as:

&lt;!-- language: lang-json --&gt;

    {
        &quot;AppSettings&quot;: {
            &quot;Version&quot;: &quot;One&quot;
        }
    }

Startup:

    public class Startup
    {
        private IConfigurationRoot _configuration;
        public Startup(IHostingEnvironment env)
        {
            _configuration = new ConfigurationBuilder()
        }
        public void ConfigureServices(IServiceCollection services)
        {
          //Here I setup to read appsettings        
          services.Configure&lt;AppSettings&gt;(_configuration.GetSection(&quot;AppSettings&quot;));
        }
    }

Model:
    
    public class AppSettings
    {
        public string Version{ get; set; }
    }

Controller:

    public class HomeController : Controller
    {
        private readonly AppSettings _mySettings;

        public HomeController(IOptions&lt;AppSettings&gt; settings)
        {
            //This is always null
            _mySettings = settings.Value;
        }
    }


`_mySettings` is always null. Is there something that I am missing here?


Getting value from appsettings.json in .net core

I have upgraded asp.net core 1.1 to an asp.net core 2. It runs fine on the local server, but when I try to deploy it to an Azure hosted web app, I received the error:

&gt; An error occurred while starting the application. .NET Core
&gt;
&gt; 4.6.00001.0 X86 v4.0.0.0    |   Microsoft.AspNetCore.Hosting version 2.0.0-rtm-26452    |    Microsoft Windows 6.2.9200

 [![enter image description here][1]][1]

Any ideas?


  [1]: https://i.stack.imgur.com/kOiWO.png

Azure WebApp Asp.NET Core 2 error: An error occurred while starting the application

C# 7.2 introduces two new types: `Span&lt;T&gt;` and `Memory&lt;T&gt;` that have better performance over earlier C# types like `string[]`.

Question: What is the difference between `Span&lt;T&gt;` and `Memory&lt;T&gt;`? Why would I use one over the other?

What is the difference between Span&lt;T&gt; and Memory&lt;T&gt; in C# 7.2?

I&#39;m working on the [Google Cloud Storage .NET client
library][1]. There are three features (between .NET, my client
library, and the Storage service) that are combining in an
unpleasant way:

- When downloading files (objects in Google Cloud Storage
terminology), the server includes a hash of the stored data. My
client code then validates that hash against the data it&#39;s
downloaded.

- A separate feature of Google Cloud Storage is that the user can
set the Content-Encoding of the object, and that&#39;s included as a
header when downloading, when the request contains a matching
Accept-Encoding. (For the moment, let&#39;s ignore the behavior when the
request doesn&#39;t include that...)

- `HttpClientHandler` can decompress gzip (or deflate) content
automatically and transparently.

When all three of these are combined, we get into trouble. Here&#39;s a
short but complete program demonstrating that, but without using my
client library (and hitting a publicly accessible file):

    using System;
    using System.Linq;
    using System.Net;
    using System.Net.Http;
    using System.Security.Cryptography;
    using System.Text;
    using System.Threading.Tasks;
    
    class Program
    {
        static async Task Main()
        {
            string url = &quot;https://www.googleapis.com/download/storage/v1/b/&quot;
                + &quot;storage-library-test-bucket/o/gzipped-text.txt?alt=media&quot;;
            var handler = new HttpClientHandler
            {
                AutomaticDecompression = DecompressionMethods.GZip
            };
            var client = new HttpClient(handler);
            
            var response = await client.GetAsync(url);
            byte[] content = await response.Content.ReadAsByteArrayAsync();
            string text = Encoding.UTF8.GetString(content);
            Console.WriteLine($&quot;Content: {text}&quot;);
            
            var hashHeader = response.Headers.GetValues(&quot;X-Goog-Hash&quot;).FirstOrDefault();
            Console.WriteLine($&quot;Hash header: {hashHeader}&quot;);
            
            using (var md5 = MD5.Create())
            {
                var md5Hash = md5.ComputeHash(content);
                var md5HashBase64 = Convert.ToBase64String(md5Hash);
                Console.WriteLine($&quot;MD5 of content: {md5HashBase64}&quot;);
            }
        }
    }

.NET Core project file:

    &lt;Project Sdk=&quot;Microsoft.NET.Sdk&quot;&gt;
      &lt;PropertyGroup&gt;
        &lt;OutputType&gt;Exe&lt;/OutputType&gt;
        &lt;TargetFramework&gt;netcoreapp2.0&lt;/TargetFramework&gt;
        &lt;LangVersion&gt;7.1&lt;/LangVersion&gt;
      &lt;/PropertyGroup&gt;
    &lt;/Project&gt;

Output:

    Content: hello world
    Hash header: crc32c=T1s5RQ==,md5=xhF4M6pNFRDQnvaRRNVnkA==
    MD5 of content: XrY7u+Ae7tCTyyK7j1rNww==

As you can see, the MD5 of the content isn&#39;t the same as the MD5
part of the `X-Goog-Hash` header. (In my client library I&#39;m using the crc32c
hash, but that shows the same behavior.)

This isn&#39;t a bug in `HttpClientHandler` - it&#39;s expected, but a pain
when I want to validate the hash. Basically, I need to at the
content before *and* after decompression. And I can&#39;t find any way
of doing that.

To clarify my requirements somewhat, I know how to prevent the decompression in `HttpClient` and instead decompress afterwards when reading from the stream - but I need to be able to do this without changing any the code that uses the resulting `HttpResponseMessage` from the `HttpClient`. (There&#39;s a lot of code that deals with responses, and I want to only make the change in one central place.)

I have a plan, which I&#39;ve prototyped and which works as far as I&#39;ve
found so far, but is a bit ugly. It involves creating a three-layer
handler:

- `HttpClientHandler` with automatic decompression disabled.
- A new handler which replaces the content stream with a new `Stream` subclass 
  which delegates to the original content stream, but hashes the data as it&#39;s read.
- A decompression-only handler, based on the Microsoft [`DecompressionHandler`][2] code.
  
While this works, it has disadvantages of:

- Open source licensing: checking exactly what I need to do in order
  to create a new file in my repo based on the MIT-licensed
  Microsoft code
- Effectively forking the MS code, which means I should probably
  make a regular check to see if any bugs have been found in it
- The Microsoft code uses internal members of the assembly, so it
  doesn&#39;t port as cleanly as it might.
  
If Microsoft made `DecompressionHandler` public, that would help a
lot - but that&#39;s likely to be in a longer timeframe than I need.

What I&#39;m looking for is an alternative approach if possible -
something I&#39;ve missed that lets me get at the content before
decompression. I don&#39;t want to reinvent `HttpClient` - the response
is often chunked for example, and I don&#39;t want to have to get into
that side of things. It&#39;s a pretty specific interception point that
I&#39;m looking for.

  [1]: https://googlecloudplatform.github.io/google-cloud-dotnet/docs/Google.Cloud.Storage.V1/index.html
  [2]: https://github.com/dotnet/corefx/blob/master/src/System.Net.Http/src/System/Net/Http/Managed/DecompressionHandler.cs


Is it possible to access the compressed data before decompression in HttpClient?

I&#39;ve got a method that reads settings from my config file like this: 

    var value = ConfigurationManager.AppSettings[key];

It compiles fine when targeting .NET Standard 2.0 only. 

Now I need multiple targets, so I updated my project file with: 

    &lt;TargetFrameworks&gt;netcoreapp2.0;net461;netstandard2.0&lt;/TargetFrameworks&gt;

But now, the compilation fails for `netcoreapp2.0` with the following error message: 

&gt; Error	CS0103	The name &#39;ConfigurationManager&#39; does not exist in the current context	(netcoreapp2.0)

Separately, I created a new .NET Core 2.0 console application (only targeting .NET Core 2.0 this time), but likewise there seems to be no `ConfigurationManager` under the namespace `System.Configuration`. 

I&#39;m quite confused because it&#39;s available under .NET Standard 2.0, so I would expect it to be available in .NET Core 2.0, as .NET Core 2.0 is .NET Standard 2.0 compliant. 

What am I missing? 


Is ConfigurationManager.AppSettings available in .NET Core 2.0?

Consider the following code:

    private static void Main(string[] args)
    {
        var ar = new double[]
        {
            100
        };

        FillTo(ref ar, 5);
        Console.WriteLine(string.Join(&quot;,&quot;, ar.Select(a =&gt; a.ToString()).ToArray()));
    }

    public static void FillTo(ref double[] dd, int N)
    {
        if (dd.Length &gt;= N)
            return;

        double[] Old = dd;
        double d = double.NaN;
        if (Old.Length &gt; 0)
            d = Old[0];

        dd = new double[N];

        for (int i = 0; i &lt; Old.Length; i++)
        {
            dd[N - Old.Length + i] = Old[i];
        }
        for (int i = 0; i &lt; N - Old.Length; i++)
            dd[i] = d;
    }

The result in Debug mode is: 100,100,100,100,100.
But in Release mode it is: 100,100,100,100,0.

What is happening?

It was tested using .NET framework 4.7.1 and .NET Core 2.0.0.


Why is code behavior different in release &amp; debug mode?

I&#39;ve read many articles, including [this one][1], yet I can&#39;t still figure out what&#39;s the difference, and they have not explained it either in simple terms or at all.

Can someone please clarify what&#39;s the difference between .NET SDK and .NET Runtime?

Update: Using comparisons would be very appreciated. Analogy alongside simple English is highly educational.


  [1]: https://jonhilton.net/2017/04/17/making-sense-of-the-different-versions-of-net-core-runtime-and-sdk/

What&#39;s the difference between SDK and Runtime in .NET Core?

### Question

How should I inject (using the standard dependency injection) a `DbContext` instance into a `IHostedService`?

### What have I tried

I currently have my `IHostedService` class take a `MainContext` (deriving from `DbContext`) instance in the constructor.

When I run the application I get:

&gt; Cannot consume scoped service &#39;Microsoft.EntityFrameworkCore.DbContextOptions&#39; from singleton &#39;Microsoft.Extensions.Hosting.IHostedService&#39;.

So I tried to make the `DbContextOptions` transient by specifying:

    services.AddDbContext&lt;MainContext&gt;(options =&gt; 
                    options.UseSqlite(&quot;Data Source=development.db&quot;), ServiceLifetime.Transient);

in my `Startup` class.

But the error remains the same, even though, according to [this solved Github issue](https://github.com/aspnet/EntityFrameworkCore/issues/6863) the `DbContextOptions` passed should have the same lifetime specified in the `AddDbContext` call.

I can&#39;t make the database context a singleton otherwise concurrent calls to it would yield concurrency exceptions (due to the fact that the database context is not guaranteed to be thread safe).

How should I inject a DbContext instance into an IHostedService?

I follow all the steps mention in MongoDB installation [documents][1] for `Ubuntu 16.04`.

 [1]: https://docs.mongodb.com/getting-started/shell/tutorial/install-mongodb-on-ubuntu/ 

**Steps 1:** 

    sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5

**Steps 2:** 

    echo &quot;deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 multiverse&quot; | sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list

**Steps 3:** 

    sudo apt-get update

**Steps 4:** 

    sudo apt-get install -y mongodb-org

**Steps 5:** 

    sudo service mongod start

when I started MongoDB got an error as: 

&gt; **Failed to start mongod.service: Unit mongod.service not found.**



Failed to start mongod.service: Unit mongod.service not found

I am using Laravel 4.2 with docker. I setup it on local. It worked without any problem but when I am trying to setup online using same procedure then I am getting error:

```
pull access denied for &lt;projectname&gt;/php, repository does not exist or may require &#39;docker login&#39;
```


is it something relevant to create repository here https://cloud.docker.com/  or need to docker login in command?

After days of study I am still not able to figure out what could be the fix in this case and what are the right steps?

I have the complete code. I can paste here if need to check certain parts. 



pull access denied repository does not exist or may require docker login

How should `yarn` be upgraded to the latest version?

Content Type	Original Author	Original Content on Stackoverflow
Question	Parusnik	View Question on Stackoverflow
Solution 1 - C#	Harit Kumar	View Answer on Stackoverflow

How to run a .NET Core console application on Linux

C# Problem Overview

C# Solutions

Solution 1 - C#

How to set the height of CKEditor 5 (Classic Editor)

Error: Could not initialize class com.android.sdklib.repository.AndroidSdkHandler

Attributions