Here are some more notes as you prepare for the latest version of the Linux+ exam.

Controlling Hardware in Linux 

• Linux actually refers to the kernel (core OS component)
• The BIOS/UEFI starts the boot loader which starts the operating system kernel of Linux
• The kernel coordinates actions between the hardware and the software
• It runs in ring zero or often called kernel space
• The user space tends to refer to everything out of the kernel space
• The Linux kernel is tasked with driving the hardware in use
• It exports data about the detected hardware using the /sys and /proc virtual file systems
• Applications often access devices using the files created in /dev; specific files represent specific devices, for example: 
  • Disk drive – /dev/sda
  • Partition – /dev/sda1
  • Mice – /dev/input/mouse0
  • Keyboards – /dev/input/event0
  • Sound card – /dev/snd/*
  • Serial ports – /dev/ttyS*
• You can tell which type of file you have (block versus character) when you list the files – note the use of the b or c character in the ls output