CODE EXAMPLE FOR SHELL

ps command

ps #command to inspect processes in device. As example:
 PID TTY           TIME CMD
  587 ttys000    0:00.38 -zsh

ps ax #a: ennumerates processes.x: shows processes not linked to terminal
 PID   TT  STAT      TIME COMMAND
    1   ??  Ss     0:53.76 /sbin/launchd