Send to background.
Syntax bg [jobspec ...] job ... &
Appending an ampersand ( & ) to the command runs the job in the background.
Resume each suspended job jobspec in the background, as if it had been started with &.
bg takes a “jobspec” available from jobs, not a PID.
If jobspec is not present, the shell's notion of the current job is used.
bg jobspec returns 0 unless run when job control is disabled or, when run with job control enabled, any specified jobspec was not found or was started without job control.
To kill a specific background job use, kill %jobspec.
bg is a BASH shell builtin and a ZSH shell builtin, to display your local syntax from the bash prompt type: help bg
Put the job with job id 0 in the background:
$ bg %0
To start a new process in the background you can do:
$ long_running_command &
Send the current foreground job to the background using CTRL-Z and bg:
$ + Stopped long_running_command
View all the background jobs using jobs:
$ jobs  Running long_running_command & - Running someothercommand &
Bring a background job to the foreground. When executed without arguments, this will take the most recent background job to the foreground:
Kill job #2:
$ kill %2
“Keep your eyes on the stars, and your feet on the ground” ~ Theodore Roosevelt
fg - Send job to foreground.
jobs - List active jobs.
wait - Wait for a process to complete.