启动进程并在ruby脚本退出后使其保持运行

Question

I'm trying to write a ruby script that:

1. Run a command/script
2. Stores the command's process pid in a file so I can check if it's still running later, and
3. the command should keep running after the ruby code exits.

I'm successful in steps 1 and 2, but it looks like the started script (ie, the child process) terminates once the ruby code is finished.

This is the last version of what I could think about (super simplified):

pid = fork do
  exec "/my/fancy/daemon/style/script"
end
File.open('tmp/process.pid', 'w') { |file| file.write(pid.to_s) }

Can you please tell me what am I doing wrong? The ultimate goal is to keep the other script (ie, the child process) running after the ruby code exits.

Answer 1

You can "detach" your child process:

Process.detach(pid)

See Process#detach for more info.

If you're running your script on a shell, and if your script is the last interactive process, your virtual terminal may exit and cause your child process to hangup as well. If you consider not sending output to the terminal, you can use Process.daemon before running exec.

See Process#daemon .