Terminal start child process

once you’ve started a process, you can background it by first stopping it (hit Ctrl-Z)
and then typing bg to let it resume in the background.
It’s now a “job”, and its stdout/stderr/stdin are still connected to your terminal.

You can start a process as backgrounded immediately by appending a “&” to the end of it:

firefox &

To run it in the background silenced:

firefox </dev/null &>/dev/null &

---

see more : https://superuser.com/questions/178587/how-do-i-detach-a-process-from-terminal-entirely