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forkgnome-terminalorphan-process

"gnome-terminal --" exits with all forks terminated

I wrote a simple C program to create orphan process:

int main(){
  int pid = fork();
  if(pid == 0){
      execl("/usr/bin/firefox", "firefox", (char*)0);
  }else{
      sleep(2);
      return 0;
  }
}

I compile this file to a.out and run the following command in terminal:

gnome-terminal -- ./a.out

This opens a new terminal and firefox, but after 2s the terminal exits and firefox terminates, but I want firefox to be an orphan process with terminal exiting.

My program is correct, because when I tried

./a.out

directly in terminal, firefox opens and when I close the present terminal manually, firefox is still there. So it must be a problem of gnome-terminal -- ....

I also replaced gnome-terminal -- with xterm -e, but things are the same.

Is there any way to open a new terminal with a.out run in the new terminal window and make firefox an orphan?(I know how to execute a.out in a new terminal and preserve the new terminal after a.out return, but I want exit the new terminal and keep firefox an orphan) .

Solution

  • Firefox is getting killed by SIGHUP because its controlling terminal goes away when gnome-terminal or xterm exits. You have two options to stop this:

    1. Do what nohup does: Set Firefox to ignore SIGHUP by doing signal(SIGHUP, SIG_IGN); before your execl.
    2. Do setsid() before your execl so that the process doesn't have a controlling terminal. Note that this might result in Firefox suddenly acquiring a controlling terminal later if it happens to open one for some reason.