https://learn.adafruit.com/running-programs-automatically-on-your-tiny-computer/sysv-init-runlevels
SysV init: Runlevels | Running Programs Automatically on Your Tiny Computer | Adafruit Learning...
Projects built on a system like the Raspberry Pi or Beaglebone Black often need a good way to run scripts or services at boot time, and ensure that they stay...
running programstiny computersysvinitrunlevels
https://notes.kodekloud.com/docs/Linux-Professional-Institute-LPIC-1-Exam-101/System-Architecture/Change-Runlevels-Boot-Targets-and-Shutdown-or-Reboot-System/page
Change Runlevels Boot Targets and Shutdown or Reboot System - KodeKloud
This article explains managing runlevels, configuring boot targets, and performing system shutdown or reboot in Linux administration.
changerunlevelsboottargetsshutdown