Starting new Process as not child of the application

[dpeter99]

Description

I'm trying to start a new Process in a multiplatform way (Win and Linux) and make the new process not a child process of the running C# App.

I found this code snippet online for running a process as non-child:

ProcessStartInfo psi = new ProcessStartInfo("YourExecutable.exe");
psi.UseShellExecute = true;
Process.Start(psi);

This still spawns the new process as a child process.

After a lot of searching, I ended up with this setup:

var linux = new ProcessStartInfo("/usr/bin/sh", new []
{
    "-c",
    "nohup /usr/bin/java"+
    " -Xmx1024M" +
    " -Xms1024M" +
    " -jar " +
     _serverJar.FullName +
    "" +
    " &"
})
{
     WorkingDirectory = _serverFolder.FullName,
     UseShellExecute = true,
};

However, this is not easily portable and requires the actual arguments to be already concatenated, which makes some mistakes possible.

Reproduction Steps

Try to use the first example to spawn a new process as non-child, on a Linux system.

Expected behavior

There should be an easy way to run a process as non-child that works on all platforms.

Actual behavior

The spawned process is a child of the app and is terminated when the c# app exits.

Regression?

No response

Known Workarounds

It is possible to call /bin/sh with the nohup and & to instruct it to make a new detached process, but this is not a portable setup.

Configuration

.NET 8
Linux (Fedora 40)
x64

Other information

No response

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[KalleOlaviNiemitalo]

The spawned process is a child of the app and is terminated when the c# app exits.

What terminates it?

[dpeter99]

What terminates it?

The operating system.

[KalleOlaviNiemitalo]

I'd expect the child process to be reparented to PID 1 (init) and continue running.

How do you start your C# app? If you start it from a terminal emulator and close the window, then that could cause a SIGHUP to be sent to the processes using that tty, including the child process of your app. Or do you start the app from cron?

[dpeter99]

I tested when starting from Rider IDE, and stopped the app in 3 ways:

• Rider stop button
• Let the app exit without doing any await on the Process
• Sending SIGKILL from htop
  And all of these resulted in the new Process closing
  In my use case, the started "child" process must survive any way the c# app might close/crash