Kestrel error: address already in use (dotnet core)

Question

Summary: it works as dotnet run, but it doesn't work as dotnet myappname.dll.

My linux skills are limited, but I am trying to go by the book so I don't mix things up (following this tutorial from Scott Hanselman):

$ cd /home/myusername/dotnettest
$ dotnet run

Now listening on: http://localhost:5123

Then I move it to /var like so:

$ sudo cp -a /home/myusername/dotnettest/bin/Debug/netcoreapp1.1/publish /var/dotnettest

Finally I test if it works there as well:

$ dotnet dotnettest.dll

Then it fails:

info: Microsoft.Extensions.DependencyInjection.DataProtectionServices[0]
      User profile is available. Using '/home/myusername/.aspnet/DataProtection-Keys' as key repository; keys will not be encrypted at rest.

Unhandled Exception: System.AggregateException: One or more errors occurred. (Error -98 EADDRINUSE address already in use) ---> Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvException: Error -98 EADDRINUSE address already in use
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.Libuv.Check(Int32 statusCode)
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Networking.UvTcpHandle.GetSockIPEndPoint()
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Http.TcpListener.CreateListenSocket()
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Http.Listener.<>c.<StartAsync>b__6_0(Object state)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.Kestrel.Internal.KestrelEngine.CreateServer(ServerAddress address)
   at Microsoft.AspNetCore.Server.Kestrel.KestrelServer.Start[TContext](IHttpApplication`1 application)
   at Microsoft.AspNetCore.Hosting.Internal.WebHost.Start()
   at Microsoft.AspNetCore.Hosting.WebHostExtensions.Run(IWebHost host, CancellationToken token, String shutdownMessage)
   at Microsoft.AspNetCore.Hosting.WebHostExtensions.Run(IWebHost host)
   at WebApplication.Program.Main(String[] args) in /home/myusername/dotnettest/Program.cs:line 27
Aborted (core dumped)

I've been careful in trying to stop nginx.

I've checked if anything is listening to :5123 with the command:

$ lsof -i tcp:5123

And nothing seems to come up.

Answer 1

The following command help to find the port and kill the process

Terminal on mac

find the process number

lsof -i: <port number>

eg lsof -i:5001

Then kill the process number

kill -9 <process number>

eg - kill -9 1600

Answer 2

in linux/mac

ps aux | grep "dotnet"

Find the process and then run

kill -9 <process_id>