put the process in background

To place a foreground process in the background: suspend the foreground process (with  Ctrl-z ) then enter the  bg  command to move the process into the background.
Ctrl+z 至關於向進程發送Kill -s 20信號
Show the status of all background and suspended jobs:  jobs
Bring a job back into the foreground:  fg %jobnumber
Bring a job back into the background:  bg %jobnumber

Regards